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A Bachelor of Arts in management sounds professional enough, but what exactly is it good for? Quite a bit, as it happens. The beauty of a degree in management is that it provides you with a diverse skill set that can be used in many parts of the business world. A management degree can help you get positions in everything from finance to marketing, allowing you to customize it to your own interests and career goals. From big corporations to small nonprofits, where a B.A. in management takes you is largely for you to decide.

While supervising others can certainly play a role in many of the jobs you can get with a B.A. in management, there’s much more to the field than just telling other people what to do. You’ll work on improving organizational structure, increasing efficiency and productivity, understanding and communicating long-term data trends and more. If these tasks sound challenging and interesting to you, then a B.A. in management — and a job in the field — could be for you.

A marketing manager is the mastermind behind a company’s advertising and branding efforts. Depending on the size and nature of the company, you could end up determining the direction of social media, all kinds of advertising, product development and more. You’ll also track the success of your marketing campaigns to determine the best use for your organization’s advertising budget going forward.

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Getting a marketing manager job is no easy feat. In addition to a relevant bachelor’s degree, such as a B.A. in management, you may also need experience in industry you plan on managing marketing for, and you may even need a master’s degree as well. Once you get the job, you may be required to travel as well. Even so, with a median annual wage of $106,130 in 2017 and the chance to be a key player in a company’s success, it could be well worth it to jump through those extra hoops.

If you’re good with statistics, data analysis and people, then sales management could be a great way to put your management BA to good use. Depending on the expectations of the company in question, you can expect to set sales goals and strategies, prepare budgets and monitor customer preferences by analyzing sales statistics. You also might end up in charge of hiring salespeople and assigning them to where they can most make a difference with their unique strengths and skills.

One downside of being a sales manager is that it can be a hectic job. Long work days and coming into the office on weekends are distinct possibilities with this position, and you may be required to travel as well. However, with exciting challenges and growing opportunities — the U.S. Bureau of Labor Statistics expects the field to expand by 5 percent by 2024 — this is another job that pays back what you put into it.

If data analysis sounded like the most interesting part of the previous two jobs, then becoming a business analyst may be the right job for you. Business analysts basically collect and study data about the company they work for and use it to figure out how the company can better itself. This often ends up meaning new software to better manage the company’s operations, so if you also have an interest in computers, you’ll be able to use it as a business analyst.

If you’re a problem solver with a great eye for spotting trends and details, then the role of business analyst could be an excellent way to use your management degree. Best of all, there’s never a shortage of companies looking for someone who can help them wrap their heads around current consumer trends.

Financial analysts are sort of like weather forecasters for the economy. They can help businesses decide things like when and where to invest and how much to charge for products and services. With today’s modern economy, it’s become invaluable to many companies to have someone around who can monitor economic conditions and provide business forecasts.

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  • If you’ve recently received a BA in management, then jobs like this can actually be a great time to add some experience to your resume, as many companies are seeking financial analysts on a freelance or temporary basis. If you’re looking for a more long-term position, then rest assured that there are still companies offering full-time positions, some of which offer the option to work remotely.

    If you love working with people and fostering new relationships, then account management may be the niche for you. Account managers more or less act as the face of a company when it comes to clients or potential clients. They identify potential clients, build relationships and pursue new business contracts on a company’s behalf.

    If you love meeting new people and can give a killer sales pitch, then account management could be a great role to explore. Entry level positions usually only require a bachelor’s degree and relevant experience, although you may find yourself looking to earn a master’s if you want to advance.

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    Boeing Co. (BA) is an aerospace and defense technology company that develops and manufactures commercial jets, military aircraft, weapons systems, and strategic defense and intelligence systems. It also provides support services to customers as well as financing for orders and deliveries. Boeing operates four separate business segments: Commercial Airplanes; Defense, Space & Security; Global Services; and Boeing Capital. The company posted a net loss of $11.9 billion on revenue of $58.2 billion in fiscal year (FY) 2020, which ended Dec. 31, 2020. Its market cap was $129.5 billion as of Sept. 30, 2021.

    Boeing was founded in 1916 as Pacific Aero Products Co. In April of the next year, founder William Boeing changed the company’s name to Boeing Airplane Co. Boeing has grown into one of the leading aerospace companies in the world, its main rival being Europe-based Airbus SE (AIR). Throughout its history, the company has dramatically increased its size through acquisitions. Boeing’s takeover targets often have been rivals who fell on hard times or were experiencing slowing growth in key parts of their business.

    Boeing has done many of its most important acquisitions to bolster its core aerospace and defense businesses, whose revenue streams tend to be less cyclical because they are primarily generated through government contracts. But Boeing has acquired other companies to strengthen its ability to supply parts and services to its commercial and military customers. Below, we look at five of these acquisitions in more detail.

    McDonnell Douglas was formed in April 1967 out of the merger between McDonnell Aircraft Corp. and The Douglas Co. By the time the company was acquired thirty years later by Boeing, its principal activities were the research, development, and manufacturing of aerospace, commercial and military avionics, and defense electronics products. However, McDonnell Douglas’ strength in the commercial aircraft market had been waning by that time, which was one of the reasons the Federal Trade Commission (FTC) found nothing anticompetitive about the acquisition and approved it. The deal combined the largest commercial-jet manufacturer in the world with a significant player in the military-aircraft industry. The combined companies accounted for 60% of the global market for large commercial jetliners at the time, helping Boeing increase capacity in order to stay competitive with rival Airbus. However, the acquisition also led to a change in culture at Boeing, a change that many regarded as being more focused on short-term financial gain than on continuing to maintain and strengthen the company’s engineering excellence.

    Rockwell International has its origins in the 1967 merger between North American Aviation and Rockwell-Standard Corp. The two companies combined to form North American Rockwell Corp. In 1973, North American Rockwell became Rockwell International. Nearly a quarter century later in December 1996, Boeing acquired Rockwell’s aerospace and defense units, forming a subsidiary that was renamed Boeing North American. Rockwell at the time was divesting assets in an attempt to refocus its business on faster-growing businesses such as manufacturing automation, semiconductors, and automotive. The two segments acquired by Boeing made missiles, sensors, space shuttles, aeroplane parts, weapons, and space systems. The acquisition was expected to significantly boost Boeing’s defense and aerospace businesses, especially space systems and information/battle management systems.

    what type of food properties allow harmful ba

    Hughes Electronics was formed in 1985 as a subsidiary of General Motors Corp. (GM) named GM Hughes Electronics. The company was a provider of telecommunication services and a leading satellite manufacturer. It was renamed Hughes Electronics Corp. in 1995. Five years later in 2000, Boeing acquired Hughes’ space and communications businesses from GM. Analysts expected the Boeing takeover to help Hughes amid a slowdown in the satellite manufacturing business, where profit margins were relatively low. Boeing integrated the units into a new business segment called Boeing Satellite Systems. The acquisition transformed Boeing into the world’s largest producer of commercial communications satellites. The deal also increased Boeing’s space-related revenues and enhanced the company’s growth prospects in information and communications products and services. These businesses were identified as key areas of growth over the next decade.

    Aviall had its origins in the early 1930s when three aircraft service and parts supply organizations merged into one company. That was the first of a number of mergers that ultimately led to the creation of Aviall. By the time Aviall was acquired by Boeing in 2006, it had become the world’s largest independent provider of new aviation parts and related aftermarket services. It was a supplier of a range of aviation batteries, hoses, wheels and brakes, and paint services. Aviall, which was Boeing’s largest acquisition since the late 1990s, became a wholly owned subsidiary of Boeing. The newly acquired company would report to Boeing’s Commercial Aviation Services segment in support of the company’s strategy to offer a broad range of value-added products and services to commercial and military customers.

    KLX became an independent, publicly traded company as a result of B/E Aerospace Inc.’s spinoff of its consumables management segment in 2014. It was acquired four years later by Boeing and had, by that time, evolved into a major independent provider of new aviation parts and aftermarket services with approximately 2,000 employees and customer service centers in more than 15 countries. KLX was marketing and distributing products to approximately 2,400 manufacturers at the time. The acquisition, which then was Boeing’s biggest in nearly 20 years, strengthened Boeing’s position within the $2.8 trillion aerospace services market. The KLX deal had two advantages. It enabled Boeing to offer larger discounts to airlines. The deal also offered Boeing the prospect of higher profits due to the relatively higher margins associated with the aircraft services business.

    Boeing Co. “Form 10-K for the fiscal year ended December 31, 2020,” Page 23. Accessed Sept. 30, 2021.

    Boeing Co. “Boeing History Chronology,” Pages 5 & 6. Accessed Oct. 1, 2021.

    The Wall Street Journal. “Boeing Agrees to Acquire Archrival McDonnell Douglas.” Accessed Sept. 30, 2021.

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  • Securities and Exchange Commission. “Boeing Co. Form 10-K for the year ended December 31, 1996.” Accessed Sept. 30, 2021.

    Dipòsit Digital de Documents de la UAB. “1998 Boeing Annual Report,” Page 34. Accessed Sept. 30, 2021.

    Boeing Co. “Boeing History Chronology,” Page 51. Accessed Sept. 30, 2021.

    Securities and Exchange Commission. “Boeing Co. Schedule 14A Information dated June 20, 1997.” Accessed Sept. 30, 2021.

    The New York Times. “McDonnell Douglas-Boeing Merger Wins F.T.C. Approval.” Accessed Sept. 30, 2021.

    The Atlantic. “The Long-Forgotten Flight That Sent Boeing Off Course.” Accessed Sept. 30, 2021.

    The Wall Street Journal. “Boeing Agrees to Acquire Two Rockwell Businesses.” Accessed Sept. 30, 2021.

    Boeing Co. “Boeing History Chronology,” Page 81. Accessed Sept. 30, 2021.

    Boeing Co. “Boeing to Acquire Aviall to Enhance Its Growing Services Businesses.” Accessed Oct. 1, 2021.

    Boeing Co. “Form 10-K for the period ending 12/31/00,” Page 37. Accessed Sept. 30, 2021.

    Boeing Co. “Boeing History Chronology,” Page 86. Accessed Sept. 30, 2021.

    Boeing Co. “Boeing Concludes Acquisition of Hughes’ Space and Communications Businesses.” Accessed Sept. 30, 2021.

    Britannica. “Hughes Electronics Corporation.” Accessed Sept. 30, 2021.

    The New York Times. “$3.75 Billion Boeing-Hughes Satellite Deal Expected.” Accessed Sept. 30, 2021.

    Boeing Co. “Boeing Concludes Purchase of Aviall, Inc.” Accessed Oct. 1, 2021.

    Google Books. “Flying Magazine Apr. 1983,” Page 11. Accessed Oct. 1, 2021.

    The New York Times. “Cooper Agrees To Sell Airmotive.” Accessed Oct. 1, 2021.

    Securities and Exchange Commission. “Aviall Inc. Form 10-K for the fiscal year ended December 31, 2005,” Page 3. Accessed Oct. 1, 2021.

    The Wall Street Journal. “Boeing Nears Purchase Of Parts Distributor Aviall.” Accessed Oct. 1, 2021.

    Boeing Co. “Boeing to Acquire Leading Aerospace Parts Distributor KLX Inc. to Enhance Services Business Growth.” Accessed Oct. 1, 2021.

    Boeing Co. “Boeing Completes Acquisition of Leading Aerospace Parts Distributor KLX Inc. to Enhance Growing Services Business.” Accessed Oct. 1, 2021.

    Boeing Co. “Strategic Acquisitions.” Accessed Oct. 1, 2021.

    KLX Inc. “Form 10-K for the fiscal year ended December 31, 2014,” Page 54. Accessed Oct. 1, 2021.

    The Wall Street Journal. “Boeing Swoops In on Plane-Parts Specialist KLX.” Accessed Oct. 1, 2021.


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    Buenos Aires goes way deeper than the tired “Paris of South America” cliche. Sure, it’s got lively cafés spilling onto the sidewalk, a wealth of Belle Epoque architecture, and grand leafy avenues leading to flowering urban parks. But Buenos Aires wouldn’t be the dynamic capital city it is without the native Argentines and immigrant Portenos who call it home and make it distinctly Buenos Aires. Local passions run deep, whether it’s for asado, tango, literature, art, or fashion. Paris could never.

    Argentina Standard Time

    Buenos Aires is a lively metropolis, and there’s something to see and do all year round. Futbol (soccer) season runs from January until May and August until mid-December. Argentina’s La Triple Corona, triple crown, runs from September until the end of the year. Travel might be tricky during Semana Santa, the Holy Week of Easter, when Argentina all but shuts down while residents travel to visit family and attend religious services. The city hosts an international tango festival in mid-August.

    Currency: Argentine Pesos

    (Check the current exchange rate)

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    Language: Spanish

    I don’t speak Spanish: No hablo Espanol/Castellano. (Argentines call their Spanish Castellano to specify its regional roots in Castilla, Spain.)

    I’m lost: Estoy perdido.

    I would like…: Me gustaria… 

    Calling Code: +54 (Argentina) 11 (Buenos Aires)

    Buenos Aires has a dependable metro/subway called Subte. Six lines connect commercial, tourist, and residential areas in the city. Trains run every three to 10 minutes depending on the line. To travel by bus or subte in Buenos Aires, you’ll need to get a rechargeable SUBE travel card. Buenos Aires has 40,000 licensed taxis and Uber access. The city is also walkable, though construction and dog droppings can make some streets difficult to pass. Want to go by bike? Buenos Aires has a free bike-share.

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  • Address: Posadas 1086/88, Buenos Aires 1011 ABB Argentina Phone:  +54 11 4321-1200Website

    The Four Seasons Hotel Buenos Aires does the chain proud. The luxury hotel is housed in a Belle Epoque mansion and connected by immaculate gardens and two swimming pools. Sophisticated suites can feature stand alone soaking bathtubs and glass chandeliers. The real action is down at the polo-inspired Pony Line bar. Oh, and Madonna stays here.

    Address: Calle Martha Salotti 445, Buenos Aires 1107BDA ArgentinaPhone: +54 11 4010-9070Website

    Faena Hotel Buenos Aires (or The Faena, as the locals call it) is the most distinct hotel in Buenos Aires. Designed by Phillipe Starck of the Delano in South Beach and The Mondrian in Los Angeles, the Faena is eye-catching on every level. Expect arabescato bathrooms and hand embroidered throws in rooms punched up with red details. The chic urban-style pool is styled with sculpture art in the water. Downstairs, El Cabaret presents a sultry tango show in the red velvet bar. 

    Address: Av. Alvear 1891, Buenos Aires 1129AAA ArgentinaPhone: + 54 11 4808-2100Website

    Old-school luxury that has charmed Presidents, Hollywood celebrities, and rock stars since the hotel opened in 1932 has been updated for the tastes of this century. Expect Hermès bath products, Louis XV furniture, and Buenos Aires’ best views from the rooftop bar. Don’t miss afternoon tea at L’Orangerie with monogrammed teacups and all the edible trimmings.

    Address: 1661 Alvear Avenue, Buenos Aires C1014AAD Argentina Phone: +54 11 5171-1234Website

    Built by an English Argentine railway executive, this Tudor Revival mansion dates to the late 1800s and underwent a $74 million renovation when Hyatt bought the building. Thank the Duhau family for the additional Neoclassical building modeled after Le Château du Marais. Today, the property is the definition of luxury with travertine marble bathrooms, crystal chandeliers, and Belle Epoque gardens. 

    Address: Calle Honduras 5860 Palermo Hollywood, Buenos Aires C1414BNJ ArgentinaPhone: + 54 11 4779-1006Website

    Ever imagined what it would be like to live like one of Argentina’s coolest artists? Book a room at Palermo’s biggest boutique hotel: the Home Hotel. Formerly a private mansion, today the upgraded style includes Scandinavian design, vintage French wallpaper, and Saarinen furnishings. The solar-power heated swimming pool is one of the city’s best outdoor spaces. Home writes an in-house city guide for guests. 

    Address: Thames 1101, Buenos Aires  1414, ArgentinaPhone: +54 11 4772-4911Website

    Sarkis is a family-style Middle Eastern restaurant that’s just the place to start a night out. Small plates of succulent lamb, marinated eggplant, and flaky nut pastries arrive willy-nilly, but it’s part of the charm. The wandering belly dancers and coffee ground readers are a good distraction between courses. Real Armenian coffee will keep you awake until the discotheque closes. Reservations accepted one week in advance. Indoor and outdoor sidewalk dining. 

    Address: Calle Cavia 2985, Buenos Aires C1425DDA ArgentinaPhone: +54 11 4809-8600Website

    La Cocina is inside of Casa Cavia, a high end retail/restaurant concept in Palermo, and one of the hardest reservations to book in Buenos Aires. In keeping with the creative vibes, La Cocina has an incredibly diverse and artistic seasonal food and cocktail menu. The interior alone is reason enough to visit. Inspired by 1920s cafes, it features white marble, brass, and antique mirrors— while still staying fresh and airy. If you can’t get into dinner, a breakfast of dulce de leche baked goods is almost as good. Dinner reservations recommended. Indoor and garden seating.

    Address: Cabrero 5099, Palermo, Buenos Aires ArgentinaPhone: +54 11 4832-5754Website

    There are lots of reasons Travel + Leisure named La Cabrera one of the best steakhouses in the world. The steak is just one of them. The asador (grill man) working a firebox filled with red-hot embers and racks of cow are another. Located in Palermo and overflowing with atmosphere, La Cabrera serves huge slabs of seasoned meat that are seared and cooked to perfection. Don’t skip the sweetbreads. The exact same menu is served down the block at La Cabrera Norte, a location built just to handle the overflow. Dinner reservations are accepted, but not always honored. Indoor and outdoor seating available.

    Address: Calle Gral Simon Bolivar 866, Buenos Aires C1066AAR ArgentinaPhone: +54 11 4040-2411Website

    Don’t leave Buenos Aires without sampling an array of empanadas. Though the hand-held street food is everywhere, finding empanadas with good dough texture and perfectly seasoned fillings can be a challenge. El Banco Rojo delivers both, with flavors like blood sausage, pancetta, and asparagus. Pair yours with a bottle of Rubia craft beer. This is a hip counter service casual spot with picnic table and stool seating. Reservations not accepted. Indoor and covered outdoor seating available. 

    Address: Avda Presidente Quintana 188, Recoleta Buenos Aires C1014ACO ArgentinaPhone: +54 9 11 4024-6376Website

    If you want a glamorous night out in Recoleta, Presidente Bar is your spot. Every detail is carefully thought out to build a cosmopolitan vibe that’s very fun: the music, the lighting, the staff—it’s all on point. The glowing back-lit bar, high ceilings, and hanging chandelier evoke a classic era. Seba Garcia, the Creative Director, creates seasonal cocktail menus to match and make cocktail trends. The food is sexy sushi. Step through the bookshelves and back in time to the ’80s speakeasy bar. Reservations recommended. Outdoor seating available. 

    Address: Junín 1760, Buenos Aires C1113 ArgentinaPhone: N/AWebsite

    Visiting Buenos Aires and not paying homage to Eva Peron’s grave in La Recoleta Cemetery is sacrilegious. Evita aside, wandering through the above ground tombs and religious symbols in this National Historic Landmark is a memorable experience.

    Address: Calle Martha Salotti 445, Buenos Aires 1107BDA ArgentinaPhone: +54 11 4952-4111Website

    Okay, so a tango show is touristy. But the Rojo Tango Show inside the sexy Faena Hotel is touristy done right. It’s intimate, fun, and might inspire a tango lesson or trip to a local milonga.

    Address: Valle Iberlucea del Dr. and Magallanes, Buenos Aires 1065 ArgentinaWebsite

    Strolling down historical and colorful Caminito (little path, in Spanish)  is like visiting an outdoor art gallery. If tango dancers and bargain souvenirs hawkers frequented art galleries.

    Address: Brandsen 805 La Boca , Buenos Aires 1161AAQ ArgentinaPhone: +54 11 4309-4700Website

    If you’re a soccer (futbol) fan, then La Bombonera is church. Visit during the season to see a match, or just take a tour and visit the dedicated museum under the grandstand if the players are on break.

    Address: Calle Defensa, Humberto I Plaza Dorrego, Buenos Aires 1065 ArgentinaWebsite

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    Peruse leather goods, antiques, and souvenirs of all shapes and sizes at this massive street fair. Many artisans make their goods right at their stalls. It’s a cross between tourist attraction and serious shopping.

    Address: Av. Figueroa Alcorta 3415, Buenos Aires C1425CLA ArgentinaPhone: +54 11 4808-6500Website

    If you have to pick one museum to see in Buenos Aires, MALBA is it. The modern building is known for its permanent collection of famed contemporary Latin American artists. Check out works by Frida Kahlo, Fernando Botero, and Antonio Berni. Talented curators also highlight local artists for seasonal exhibits.

    Address: Av. San Juan 350 San Telmo , Buenos Aires C1147AAO ArgentinaPhone: +54 011 4361-6919Website

    This experimental modern art museum is housed inside a former tobacco factory and holds more than 7,000 pieces of modern and contemporary art. The focus is on modern art from an Argentine perspective.

    Address: Av. del Libertador 1473, Buenos Aires, ArgentinaPhone: +54 11 5280-9900Website

    Located in the upscale Recoleta neighborhood, the fine arts museum is home to an astounding collection of 19th-century European art—widely considered the most important collection in South America. Expect to see work from artists like Goya, Van Gogh, and Toulouse Lautrec. 

    Address: Santa Fe 2729 Barrio Norte, Buenos Aires 1425 ArgentinaWebsite

    The shop-filled building brings designers and artists together in one of the hippest art and design spaces in Buenos Aires. Retailers include Greens for elevated men’s and women’s basics and Little L for vintage clothes. Contemporary art galleries offer inspiration, and there’s a cute patio cafe for cafe chicos.

    Address: Humberto 1 412 San Telmo, Buenos Aires C1103ACJ ArgentinaPhone: +54 11 4361-5019Website

    This labyrinth boutique has specialized in early- and mid-century vintage clothing and homewares since 1937. It’s packed with everything from antique beaded necklaces to rare vintage crystal to lace wedding gowns.

    Address: Hipódromo de Palermo Area, Buenos Aires, ArgentinaPhone: +54 11 6483-9161Website

    After years of working in the Paris fashion industry, owner Maydi returned to her native Argentina and launched a free trade, high fashion knitwear label using native materials and dyes. The showroom (which doubles as her living room) is by appointment only.

    Address: Ugarteche 3338 pb1, Buenos Aires  C1425 EOE ArgentinaPhone: +54 11 3094-2596Website

    If you have leather on your Argentina shopping list, Las Cabrera is the place to buy it. No single piece is alike, and every purse, backpack, wallet, and bag is made by hand, and from high-quality Argentine leather.

    Address: Av. Alvear 1680, Buenos Aires C1014 AAQ ArgentinaPhone: +54 11 4311-5360Website

    Visiting Fueguia 1833 is an Argentinian sensory experience. The perfumery is inspired by founder Julian Bedel’s travels throughout Patagonia. Pro tip: the handcrafted candles make perfect gifts.

    Address: Avenida Santa Fe 1860, Buenos Aires C1123AAN ArgentinaPhone: +54 11 4813-6052Website

    Buenos Aires has a serious literary scene. Celebrate it at El Ateneo Grand Splendid, housed in a grand theater built in 1919. The enormous space is now packed floor-to-ceiling with books and ornate original fixtures. The former stage now houses a cafe.

    Recoleta and Palermo remain the reigning king and queen of Buenos Aires neighborhoods. Palermo is hip and artsy with boutique hotels and trendy cafes. Recoleta is classic Argentina with luxury hotels, glamorous bars, and cosmopolitan culture. Villa Crespo, the barrio just southwest of Palermo, is the up and coming prince. The former shoe factory worker neighborhood is now attracting artists and nightlife to its cobbled streets.

    Buenos Aires has a warm and temperate climate. Remember, the seasons are opposite to that of the northern hemisphere. You won’t see snow, but expect about four days of rain per month. June is generally the driest month, and March is the wettest. January is the hottest month with an average temperature of 86°F (30°C). July is the coldest with an average temperature of 44°F (7°C). No matter the time of year, nights are always chillier.

    Porteno Spanish: Spanish language guide with local slangiOs | Android

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    Wiki User

    There are various food properties that allow harmful bacteria to
    multiply rapidly; one being the food is low in acid. Two more are
    moisture and that the food is high in protein.

    Wiki User

    Foods that are high in acid do not allow harmful bacteria to
    multiply rapidly.

    what type of food properties allow harmful ba

    Foods that are high in acid do not allow harmful bacteria to
    multiply rapidly.

    There are various food properties that allow harmful bacteria to
    multiply rapidly; one being the food is low in acid. Two more are
    moisture and that the food is high in protein.

    bacteria

    Multiply

    Bacteria Double Their Numbers In 20 Minutes

    if its in warm weather the bacteria will multiply more rapidly
    than in a colder climate the bacteria multiples by the minute it
    may double it may triple depending on the climate the warmer the
    faster the bacteria will multiply and will cause food spoil.

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  • The bacteria in the food will be dormant. The bacteria that
    causes food poisoning will not multiply rapidly.

    They can reproduce quite rapidly. Once inside the body they can
    release enzymes and toxins which can be harmful to us.

    Under optimum conditions the average generation time is 30-60
    minutes. bacteria multiply rapidly in comparison to other
    organisms

    because antibiotics affect the balance of bacteria in the
    vagina, allowing such organisms as T. vaginalis to multiply more
    rapidly.

    Bacteria can grow rapidly in the TDZ, also known as the
    Temperature Danger Zone, which is 41f – 140f.

    Micro B Life

    For example bacteria grow rapidly in high-protein foods such as meat poultry eggs dairy and seafood. pH — Microorganisms thrive in a pH range above 4.6. That’s why acidic foods like vinegar and citrus juices are not favorable foods for pathogenic bacteria to grow however they may survive in these foods.

    Bacteria grow most rapidly in the range of temperatures between 40 °F and 140 °F doubling in number in as little as 20 minutes.

    Keeping potentially hazardous foods cold (below 5°C) or hot (above 60°C) stops the bacteria from growing. The food safety standards specify that potentially hazardous foods must be stored displayed and transported at safe temperatures and where possible prepared at safe temperatures.

    Potentially Hazardous Foods (PHFs) are foods which support rapid growth of microorganisms. Examples of PHFs include all raw and cooked meats poultry milk and milk products fish shellfish tofu cooked rice pasta beans potatoes and garlic in oil.

    what type of food properties allow harmful ba

    All bacteria need is food and moisture to survive. Time we know is needed to allow them to multiply. The temperature has to be right for the specific type of bacteria but most like temperatures within what we call the ‘danger zone’.

    Bacteria reproduce by binary fission. In this process the bacterium which is a single cell divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two (replicates). … Each daughter cell is a clone of the parent cell.

    Why it matters: Bacteria are among the fastest reproducing organisms in the world doubling every 4 to 20 minutes. Some fast-growing bacteria such as pathogenic strains of E.

    Different types of food poisoning bacteria can live on a range of foods but most prefer food that is moist and high in protein. For example: Meat poultry eggs shellfish milk and dairy products cooked rice pasta and any product made from the foods listed.

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  • Harmful bacteria are called pathogenic bacteria because they cause disease and illnesses like strep throat staph infections cholera tuberculosis and food poisoning.

    Bacteria can live in hotter and colder temperatures than humans but they do best in a warm moist protein-rich environment that is pH neutral or slightly acidic. There are exceptions however. Some bacteria thrive in extreme heat or cold while others can survive under highly acidic or extremely salty conditions.

    Not all bacteria are harmful and some bacteria that live in your body are helpful. For instance Lactobacillus acidophilus — a harmless bacterium that resides in your intestines — helps you digest food destroys some disease-causing organisms and provides nutrients.

    A spore is a cell that certain fungi plants (moss ferns) and bacteria produce. Spores are involved in reproduction. … The bacteria Clostridia form spores. These spores create the bacteria that cause a rare condition called gas gangrene and a type of colitis that is linked to use of antibiotics.

    There are four things that can impact the growth of bacteria. These are: temperatures moisture oxygen and a particular pH.

    The best way to avoid bacterial growth on food is to follow proper food-handling instructions: Keep meat cold wash your hands and any surface that comes in contact with raw meat never place cooked meat on a platter that held raw meat and cook food to safe internal temperatures.

    chicken turkey goose duck known poultry? fragile short shelf life. high protein moisture content will support rapid growth of bacteria( salmonella campylobacter) flesh is firm and elastic store at 41 or less must be USDA inspected.

    When the conditions are right with warm temperatures moisture and the nutrients in food then bacterial contamination can spread quite quickly.

    Unlike more complex forms of life bacteria carry only one set of chromosomes instead of two. They reproduce by dividing into two cells a process called binary fission. Their offspring are identical essentially clones with the exact same genetic material.

    Bacteria reproduce through a process called binary fission. During binary fission the chromosome copies itself forming two genetically identical copies. … Binary fission can happen very rapidly. Some species of bacteria can double their population in less than ten minutes!

    However the bacterial chromosome is found in a specialized region of the cell called the nucleoid. Copying of DNA by replication enzymes begins at a spot on the chromosome called the origin of replication.

    Pathogens such as Salmonella Campylobacter and E. coli may be found in our food-producing animals. Care in processing transport storage preparing and serving of food is necessary to reduce the risk of contamination. Food poisoning bacteria can multiply very quickly particularly in certain conditions.

    The main way that contamination spreads in the kitchen is by our hands. Too often people don’t wash their hands before making food. And people often don’t wash their hands between handling possibly contaminated foods such as meat and other foods that are less likely to be contaminated such as vegetables.

    Some bacteria produce toxins when they grow in food. Because the toxins themselves are harmful the bacteria don’t need to multiply in the intestine to make someone ill so the symptoms come on very quickly. … In some cases food poisoning can cause very serious illness or even death.

    Bacteria feed in different ways. Heterotrophic bacteria or heterotrophs get their energy through consuming organic carbon. Most absorb dead organic material such as decomposing flesh. Some of these parasitic bacteria kill their host while others help them.

    The primary harmful effects of microbes upon our existence and civilization is that they are an important cause of disease in animals and crop plants and they are agents of spoilage and decomposition of our foods textiles and dwellings.

    They cause various diseases like typhoid cholera tuberculosis tetanus etc. Examples of some harmful bacteria: … Agrobacterium Erwinia etc are the pathogenic bacteria causing plant diseases. Animals and pets also suffer from bacterial infections caused by Brucella Pasteurella etc.

    Microbes can be transferred from one food to another by using the same knife cutting board or other utensil without washing the surface or utensil in between uses. A food that is fully cooked can become re-contaminated if it touches other raw foods or drippings from raw foods that contain pathogens.

    A team of researchers including Stanford scientists has discovered that certain single-celled infectious bacteria can tell the difference between light and dark and actually increase their infectiousness 10-fold when hit by sunlight.


    AnswerPrime.com


    Easy answers to Difficult Questions

    What kind of food residential or commercial properties do not enable hazardous germs to increase quickly?

    Response 1

    Foods that are extremely acidic tend to prevent germs development. Lot of times, germs do not adapt well to acidic environments, so having a food with a really low pH will assist to make certain that the germs can’t prosper in such an environment. Vegetables and fruits are fine examples of these kinds of food.

    what type of food properties allow harmful ba

    Response 2

    the potatoes have high sugar concentrations and although these potatoes were various we might flare results that their sugar concentrations had in various environments. The potatoes in sample a, were positioned in pure water. this developed a hypertonic environment and triggered the potatoes to attract water from its environments. we saw the opposite occur with the potatoes in sample b when positioned in the salt chloride service. the potatoes in this case remained in a hypotonic service and for that reason lost water to their environments.

    Response 3

    Alright, i’m gon na attempt to describe this as great as possible. the law of preservation resembles a collection overtime. It never ever alters. no matter how you alter the constituent parts.

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  • For example, bacteria grow rapidly in high-protein foods such as meat, poultry, eggs, dairy, and seafood. pH — Microorganisms thrive in a pH range above 4.6. That’s why acidic foods like vinegar and citrus juices are not favorable foods for pathogenic bacteria to grow; however, they may survive in these foods.

    Between 4°C and 60°C (or 40°F and 140°F) is the “Danger Zone.” Keep food out of this temperature range because bacteria will multiply rapidly. Between 0°C and 4°C (or 32°F and 40°F), most bacteria will survive but will not multiply quickly.

    After a food is cooked and its temperature drops below 130 degrees, these spores germinate and begin to grow, multiply and produce toxins. One such spore-forming bacterium is Clostridium botulinum, which can grow in the oxygen-poor depths of a stockpot, and whose neurotoxin causes botulism.

    Properly cooked foods are safe to eat because heat destroys pathogens present. Raising food to a predetermined temperature by boiling, roasting, frying, baking, broiling or grilling gets the job done. The US Department of Agriculture reports minimum cooking temperatures for a variety of foods.

    Potentially Hazardous Foods (PHFs) are foods which support rapid growth of microorganisms. Examples of PHFs include all raw and cooked meats, poultry, milk and milk products, fish, shellfish, tofu, cooked rice, pasta, beans, potatoes and garlic in oil.

    what type of food properties allow harmful ba

    Avoid Room Temperature: There’s a good reason why the rule of thumb is to “keep cold foods cold and hot foods hot.” Bacteria multiply rapidly between 40 degrees Fahrenheit and 140 degrees F. So it’s best to keep hot cooked food at 140 degrees or higher, and cold cooked food at 40 degrees or lower.

    chicken, turkey, goose, duck known poultry? fragile short shelf life. high protein , moisture content, will support rapid growth of bacteria( salmonella, campylobacter) flesh is firm and elastic store at 41 or less must be USDA inspected.

    Foodborne pathogens can be transmitted to humans via food. High-protein foods will not support rapid growth of bacteria. Food-borne illness can cause some flu-like symptoms.

    The main way that contamination spreads in the kitchen is by our hands. Too often, people don’t wash their hands before making food. And people often don’t wash their hands between handling possibly contaminated foods such as meat and other foods that are less likely to be contaminated, such as vegetables.

    Bacteria reproduce by binary fission. In this process the bacterium, which is a single cell, divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two (replicates). … Each daughter cell is a clone of the parent cell.

    Bacteria are transmitted to humans through air, water, food, or living vectors. The principal modes of transmission of bacterial infection are contact, airborne, droplet, vectors, and vehicular. Preventive measures have a dramatic impact on morbidity and mortality.

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  • Some bacteria produce toxins when they grow in food. Because the toxins themselves are harmful, the bacteria don’t need to multiply in the intestine to make someone ill, so the symptoms come on very quickly. … In some cases, food poisoning can cause very serious illness or even death.

    To keep foods safe, remember to keep foods out of the Temperature Danger Zone, and if your food sits out, make a habit of getting your cold food in the refrigerator within two hours. Your hot food should be cooled quickly and put away in that timeframe as well.

    Not all bacteria are harmful, and some bacteria that live in your body are helpful. For instance, Lactobacillus acidophilus — a harmless bacterium that resides in your intestines — helps you digest food, destroys some disease-causing organisms and provides nutrients.

    Spore formation

    Spores survive normal cooking and germinate during long, slow cooling. The vegetative bacteria released will then start multiplying and may produce toxins.

    When the conditions are right, with warm temperatures, moisture and the nutrients in food, then bacterial contamination can spread quite quickly.

    MOISTURE. Food poisoning bacteria must have moisture to stay alive. Bacteria will not multiply in dried foods such as dried pasta, rice, biscuits. As soon as water/liquid is added however, bacterial multiplication starts again.

    Which bacteria can be prevented by controlling flies inside and outside the operation? Shigella spp.

    Answer: Water is the only substance which does not prevent the growth of bacteria.

    Such raw foods like raw carrots, raw onions, raw garlic, ginger, potatoes and other raw foods do not support bacteria growth. Raw foods have a longer shelf-life than any other cooked foods.

    The Answer…

    TCS food, like dairy products, eggs, meat, and poultry support the growth of bacteria, hence ideal for bacterial growth. Other TCS food items are milk, shellfish, crustaceans, baked potatoes, sprouts, sliced melons, cut leafy vegetables, tofu, and fish.

    Bacteria grow well in food with high levels of moisture. The amount of moisture available in food for this growth is called water activity. The scale ranges from 0.0 to 1.0. The higher the value the more moisture in the food.

    high-protein foods will not support rapid growth of bacteria, true or false? false.

    These conditions include temperature, moisture, pH and environmental oxygen. Understanding the optimal conditions for bacterial growth can potentially help you reduce your risk for bacterial infections and food poisoning.

    There are four things that can impact the growth of bacteria. These are: temperatures, moisture, oxygen, and a particular pH.

    Bacteria feed in different ways. Heterotrophic bacteria, or heterotrophs, get their energy through consuming organic carbon. Most absorb dead organic material, such as decomposing flesh.

    Harmful bacteria are called pathogenic bacteria because they cause disease and illnesses like strep throat, staph infections, cholera, tuberculosis, and food poisoning.

    Bacteria reproduce through a process called binary fission. During binary fission, the chromosome copies itself, forming two genetically identical copies. … Binary fission can happen very rapidly. Some species of bacteria can double their population in less than ten minutes!

    However, the bacterial chromosome is found in a specialized region of the cell called the nucleoid. Copying of DNA by replication enzymes begins at a spot on the chromosome called the origin of replication.

    Fractional distillation is the process in which the alkanes in petroleum can be partly separated. This is due to the petroleum having different boiling points. The process starts off with the heating of crude oil for it to vaporize. The vaporized crude oil is then fed into the bottom of the distillation tower. The resulting vapor rises through a vertical column. As the gases rises through the distillation tower, its temperature decreases. Thus, certain hydrocarbons begin to condense and run off at varying levels. Each level-specific condensed fraction contains hydrocarbon molecules that has a similar number of carbon atoms. These “cuts” of boiling point allow numerous hydrocarbons to be separated out in a single process. The cooling of the tower height allows for the separation. Subsequent to the refinement, individual fuels may undergo more refinement to remove existing contaminants or substances so as to improve the quality of the fuel through cracking.

    Answer:

    D. Fire discourages grazing by large animals so grass can grow higher.

    Explanation:

    Fire allows trees to grow and provide shade for the grasses. … Seeds can germinate in an area that has been cleared by a fire.

    what type of food properties allow harmful ba

    Answer:

    Explanation:

    Factors that affect respiratory rate are; Again gender, size, anxiety,weight, pain, medication

    Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms.

    Some bacteria are harmful, but most serve a useful purpose. They support many forms of life, both plant and animal, and they are used in industrial and medicinal processes.

    Bacteria are thought to have been the first organisms to appear on earth, about 4 billion years ago. The oldest known fossils are of bacteria-like organisms.

    Bacteria can use most organic and some inorganic compounds as food, and some can survive extreme conditions.

    A growing interest in the function of the gut microbiome is shedding new light on the roles bacteria play in human health.

    what type of food properties allow harmful ba

    Bacteria are single-cell organisms that are neither plants nor animals.

    They usually measure a few micrometers in length and exist together in communities of millions.

    A gram of soil typically contains about 40 million bacterial cells. A milliliter of fresh water usually holds about one million bacterial cells.

    The earth is estimated to hold at least 5 nonillion bacteria, and much of the earth’s biomass is thought to be made up of bacteria.

    There are many different types of bacteria. One way of classifying them is by shape. There are three basic shapes.

    There are many variations within each shape group.

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  • Bacterial cells are different from plant and animal cells. Bacteria are prokaryotes, which means they have no nucleus.

    A bacterial cell includes:

    Bacteria feed in different ways.

    Heterotrophic bacteria, or heterotrophs, get their energy through consuming organic carbon. Most absorb dead organic material, such as decomposing flesh. Some of these parasitic bacteria kill their host, while others help them.

    Autotrophic bacteria (or just autotrophs) make their own food, either through either:

    Bacteria that use photosynthesis are called photoautotrophs. Some types, for example cyanobacteria, produce oxygen. These probably played a vital role in creating the oxygen in the earth’s atmosphere. Others, such as heliobacteria, do not produce oxygen.

    Those that use chemosynthesis are known as chemoautotrophs. These bacteria are commonly found in ocean vents and in the roots of legumes, such as alfalfa, clover, peas, beans, lentils, and peanuts.

    Bacteria can be found in soil, water, plants, animals, radioactive waste, deep in the earth’s crust, arctic ice and glaciers, and hot springs. There are bacteria in the stratosphere, between 6 and 30 miles up in the atmosphere, and in the ocean depths, down to 32,800 feet or 10,000 meters deep.

    Aerobes, or aerobic bacteria, can only grow where there is oxygen. Some types can cause problems for the human environment, such as corrosion, fouling, problems with water clarity, and bad smells.

    Anaerobes, or anaerobic bacteria, can only grow where there is no oxygen. In humans, this is mostly in the gastrointestinal tract. They can also cause gas, gangrene, tetanus, botulism, and most dental infections.

    Facultative anaerobes, or facultative anaerobic bacteria, can live either with or without oxygen, but they prefer environments where there is oxygen. They are mostly found in soil, water, vegetation and some normal flora of humans and animals. Examples include Salmonella.

    Mesophiles, or mesophilic bacteria, are the bacteria responsible for most human infections. They thrive in moderate temperatures, around 37°C. This is the temperature of the human body.

    Examples include Listeria monocytogenes, Pesudomonas maltophilia, Thiobacillus novellus, Staphylococcus aureus, Streptococcus pyrogenes, Streptococcus pneumoniae, Escherichia coli, and Clostridium kluyveri.

    The human intestinal flora, or gut microbiome, contains beneficial mesophilic bacteria, such as dietary Lactobacillus acidophilus.

    Extremophiles, or extremophilic bacteria, can withstand conditions considered too extreme for most life forms.

    Thermophiles can live in high temperatures, up to 75 to 80°C, and hyperthermophiles can surivive in temperatures up to 113°C.

    Deep in the ocean, bacteria live in total darkness by thermal vents, where both temperature and pressure are high. They make their own food by oxidizing sulfur that comes from deep inside the earth.

    Other extremophiles include:

    Extremophiles can survive where no other organism can.

    Bacteria may reproduce and change using the following methods:

    Some bacteria produce endospores, or internal spores, while others produce exospores, which are released outside. These are known as cysts.

    Clostridium is an example of an endospore-forming bacterium. There are about 100 species of Clostridium, including Clostridium botulinim (C. botulinim) or botulism, responsible for a potentially fatal kind of food poisoning, and Clostridium difficile (C. Difficile), which causes colitis and other intestinal problems.

    Bacteria are often thought of as bad, but many are helpful. We would not exist without them. The oxygen we breathe was probably created by the activity of bacteria.

    Many of the bacteria in the body play an important role in human survival. Bacteria in the digestive system break down nutrients, such as complex sugars, into forms the body can use.

    Non-hazardous bacteria also help prevent diseases by occupying places that the pathogenic, or disease-causing, bacteria want to attach to. Some bacteria protect us from disease by attacking the pathogens.

    Bacteria take in nitrogen and release it for plant use when they die. Plants need nitrogen in the soil to live, but they cannot do this themselves. To ensure this, many plant seeds have a small container of bacteria that is used when the plant sprouts.

    Lactic acid bacteria, such as Lactobacillus and Lactococcus together with yeast and molds, or fungi, are used to prepare foods such as as cheese, soy sauce, natto (fermented soy beans), vinegar, yogurt, and pickles.

    Not only is fermentation useful for preserving foods, but some of these foods may offer health benefits.

    For example, some fermented foods contain types of bacteria that are similar to those linked with gastrointestinal health. Some fermentation processes lead to new compounds, such as lactic acid, which that appear to have an anti-inflammatory effect.

    what type of food properties allow harmful ba

    More investigation is needed to confirm the health benefits of fermented foods.

    Bacteria can break down organic compounds. This is useful for activities such as waste processing and cleaning up oil spills and toxic waste.

    The pharmaceutical and chemical industries use bacteria in the production of certain chemicals.

    Bacteria are used in molecular biology, biochemistry and genetic research, because they can grow quickly and are relatively easy to manipulate. Scientists use bacteria to study how genes and enzymes work.

    Bacteria are needed to make antibiotics.

    Bacillus thuringiensis (Bt) is a bacterium that can be used in agriculture instead of pesticides. It does not have the undesirable environmental consequences associated with pesticide use.

    Some types of bacteria can cause diseases in humans, such as cholera, diptheria, dysentery, bubonic plague, pneumonia, tuberculosis (TB), typhoid, and many more.

    If the human body is exposed to bacteria that the body does not recognize as helpful, the immune system will attack them. This reaction can lead to the symptoms of swelling and inflammation that we see, for example, in an infected wound.

    In 1900, pneumonia, TB, and diarrhea were the three biggest killers in the United States. Sterilization techniques and antibiotic medications have led to a significant drop in deaths from bacterial diseases.

    However, the overuse of antibiotics is making bacterial infection harder to treat. As the bacteria mutate, they become more resistant to existing antibiotics, making infections harder to treat. Bacteria transform naturally, but the overuse of antibiotics is speeding up this process.

    “Even if new medicines are developed, without behaviour change, antibiotic resistance will remain a major threat.”

    World Health Organization (WHO)

    For this reason, scientists and health authorities are calling on doctors not to prescribe antibiotics unless it is necessary, and for people to practice other ways of preventing disease, such as good food hygiene, hand washing, vaccination, and using condoms.

    Recent research has led to a new and growing awaress of how the human body interacts with bacteria, and particularly the communities of bacteria living in the intestinal tract, known as the gut microbiome, or gut flora.

    In 2009, researchers published findings suggesting that women with obesity were more likely to have a particular kind of bacteria, Selenomonas noxia (S. noxia), in their mouth.

    In 2015, scientists at the University of North Carolina found that the intestines of people with anorexia contain “very different” bacteria, or microbial commiunities, compared with people who do not have the condition. They suggest that this may have a psychological impact.

    Over 2,000 years ago, a Roman author, Marcus Terentius Varro, suggested that disease may be caused by tiny animals that floated in the air. He advised people to avoid marshy places during building work because they might contain insects too small for the eye to see that entered the body through the mouth and nostrils and cause diseases.

    In the 17th century, a Dutch scientist, Antonie van Leeuwenhoek created a single-lens microscope with which he saw what he called animalcules, later known as bacteria. He is considered to be the first microbiologist.

    In the 19th century, the chemists Louis Pasteur and Robert Koch said that diseases were caused by germs. This was known as the Germ Theory.

    In the 1910, the scientist Paul Ehrlich announed the development of the first antibiotic, Salvarsan. He used it to cure syphilis. He was also the first scientist to detect bacteria by using stains.

    In 2001, Joshua Lederburg coined the term “gut microbiome,” and scientists worldwide are currently seeking to describe and understand more precisely the structures, types, and uses of “gut flora,” or bacteria in the human body.

    In time, this work is expected to shed new light a wide range of health conditions.

    Last medically reviewed on February 12, 2019

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    Typhoid is a bacterial infection that can be fatal without antibiotic treatment. Learn more.

    New research suggests that COVID-19 may have worsened antibiotic resistance in hospitals.

    Discover the definition of communicable diseases, the symptoms of the different types, and how to avoid them here.

    Otitis media is inflammation of the middle ear due to infection. It is common in children and often occurs after a cold or respiratory infection…

    New research of a sample predominantly made of heterosexual people found a link between attractiveness and stronger immunity.

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    Bacteria can live in hotter and colder temperatures than humans, but they do best in a warm, moist, protein-rich environment that is pH neutral or slightly acidic. There are exceptions, however. Some bacteria thrive in extreme heat or cold, while others can survive under highly acidic or extremely salty conditions. Most bacteria that cause disease grow fastest in the temperature range between 41 and 135 degrees F, which is known as THE DANGER ZONE.

    what type of food properties allow harmful ba

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    what type of food properties allow harmful ba

    Home > Books > Poisoning – From Specific Toxic Agents to Novel Rapid and Simplified Techniques for Analysis

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    Submitted: December 18th, 2016 Reviewed: May 31st, 2017 Published: December 20th, 2017

    DOI: 10.5772/intechopen.69953

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    In the environment, there are polluting substances that can cause adverse reactions in human beings when entering the body through different ways (ingestion, inhalation, injection, or absorption). The main pollutants can be poisons, chemical compounds, toxic gases, and bacterial toxins. These can be found in different places and their effects depend on the dose and exposure time. Furthermore, foodborne diseases (FBDs) can cause disability; these diseases can be caused by toxins produced by bacteria or other toxic substances in the food, which can cause severe diarrhea, toxic shock syndrome, debilitating infections such as meningitis and even death. FBDs are transmitted through food contaminated with pathogenic microorganisms that have multiple factors of virulence, which gives them the ability to cause an infection; some bacterial genres can produce toxins directly in the food, but other genres can produce them once they have colonized the intestine. Among the pathogens involved in FBDs that are also considered to be toxigenic are Salmonella spp., Vibrio parahaemolyticus, Vibrio cholerae, Staphylococcus aureus, Clostridium botulinum, Clostridium perfringens, Bacillus cereus, Listeria monocytogenes. Foodborne diseases can be prevented and acute diarrhea syndromes, fever and even death from dehydration can be avoided, especially in children under the age of 5 and in immunocompromised people.

    *Address all correspondence to: [email protected]

    The main pollutants can be poisons, chemical compounds, toxic gases, and bacterial toxins. There are several diseases that human beings can acquire by ingesting some type of pollutants, for example, chemical contamination can lead to acute poisoning or long-term diseases such as cancer. Furthermore, foodborne diseases (FBDs) can cause disability; these diseases can be caused by the toxins produced by the bacteria or other toxic substances in food [1].

    It is important to know that poisoning is the cause of morbidity and mortality worldwide. There are different types of intoxication: (a) intoxication caused by chemical substances (such as drugs, pesticides, heavy metals, gases, and solvents) where the patient has direct contact with the toxic substance, and (b) food poisoning, of which the transmission vehicle is contaminated food with pathogens or chemical products. Nowadays, chemical poisoning is a health problem; about six million chemicals are known, of which 80,000 to 100,000 are commonly used in different daily products. In 2006, the World Health Organization (WHO) estimated that more than 25% of poisonings and 5% of cases of cancer, neuropsychiatric disorders, and vascular diseases worldwide were caused by chemical exposure [1, 2].

    It is difficult to diagnose chemical poisoning, since a chronological record of the patient’s life is required, considering the exposure routes, dose, and time of exposure to the chemical. However, there are protocols that facilitate the diagnosis of chemical poisoning and how to treat incidents from chemical poisoning [1].

    Furthermore, food poisoning or foodborne disease (FBD) is one of the main problems in public health worldwide. According to the WHO, each year 600 million people around the world, or 1 out of 10, become ill after consuming contaminated food. Among all these people, 420,000 die, including 125,000 children under 5 years of age, due to the vulnerability of this population to develop a diarrheal syndrome, about 43% of FBDs occur in these patients. About 70% of FBDs result from food contaminated with a microorganism [2–4].

    Among the microorganisms causing FBDs are bacteria that have different virulence factors that give them the ability to cause a disease; among these factors, we can find toxins that can be produced in food or once the pathogen has colonized the digestive tract.

    It is to be noted that the aim of this chapter is to convey information about some characteristics of the main pathogens producing toxins in food, the diseases they can cause, their complications and treatment options as well as the main sources of contamination in restaurants or street markets.

    A bacterial toxin is a macromolecule mainly of protein origin, which can cause toxic damage in a specific organ of the host [5]. Toxins can be divided in endotoxins and exotoxins:

    Endotoxins or lipopolysaccharides (LPS): These are the components of the outer membrane of the Gram-negative bacteria; they are considered the most important antigen of the bacteria; they are released into the medium after different processes such as lysis and cell division. This endotoxin is capable of causing endotoxic shock and tissue damage [5–7].

    LPS are formed by three regions [7]:

    Lipid A is a glycolipid formed by a disaccharide (glucosamine) bound to fatty acids, that are usually capric, lauric, myristic, palmitic, and stearic acids, which are inserted in the outer membrane of the bacterium.

    The nucleus a heteropolysaccharide derived from hexoses and heptoses.

    Lipid A and the nucleus are bound by the sugar acid 2-keto-3-deoxyoctanate (KDO).

    The O chain is a repeating unit polymer of 1–8 glycosidic residues; this polymer is highly variable among bacterial species and genus.

    In addition to the pyrogenicity of the endotoxin, an important role has been attributed to the adherence mechanism of the bacteria to the host cell; since in previous studies, it has been observed that when LPS is modified or not expressed, the adherence observed is modified or inhibited.

    Exotoxins: These are the macromolecules of protein origin, which are produced and later released to the medium by the microorganism. Depending on their mechanism of action, exotoxins are divided as follows:

    what type of food properties allow harmful ba

    Toxins Type I. These toxins modify the host’s cells without internalizing in the cells; for example, the superantigens produced by Staphylococcus aureusand Streptococcus pyogenes.

    Toxins Type II. Within this group there are hemolysins and phospholipases; this group of toxins is characterized by pore formation and/or destroying the membranes of the host cells. With this virulence factor, the pathogen can invade the host cell; for example, aerolysin and GCAT protein produced by Aeromonasspp.

    Toxins Type III. These toxins are known as A/B due to their binary structure. Fraction B has the function of binding to the receptor of the cell and fraction A is the unit that possesses enzymatic activity, which, depending on the toxin and its mechanism of action, will be the damage to the cell; for example, the Shiga toxin produced by Escherichia coliO157:H7, the Cholera toxin (Ctx) produced by Vibrio cholerae, and the Anthrax toxin produced by Bacillus anthracis[5, 6].

    Exotoxins of Gram-negative enteropathogenic bacteria play an important role in the pathogenesis of diarrheal disease, causing hypersecretion of liquids without the destruction and death of intestinal mucosal cells. These toxins are generically referred to as enterotoxins that are different from cytotoxins [8].

    There are also two other groups of toxins, those that alter the cytoskeleton and those with neurotoxic activity; however, some toxins may present activity corresponding to more than one of the groups described in Table 1.

    Classification of enteric toxins.

    Source: Adapted from Sears et al. [8].

    Toxins produced by pathogens involved in foodborne diseases are as follows:

    Cholera toxin (Ctx) (Vibrio cholerae), Thermolabile toxin (LT) Thermostable toxin (ST) (Enterotoxigenic E. coli), Shiga Toxin (Shigella dysenteriaeand E. coliO157:H7) Botulinum toxin (BTX) (Clostridium botulinum), CPE Enterotoxin (Clostridium perfringens), Alpha-Toxin, Beta-Toxin, Epsilon-Toxin and Iota-Toxin (C. perfringens), Toxin A/Toxin B (Clostridium difficile), Enterotoxins (A, B, C1, C2, D and E, G, H, I, J), Toxic Shock Syndrome Toxin (TSST-1), Cereulide, and hemolysin BL (HBL), nonhemolytic enterotoxin (NHE) (S. aureus), Citotoxin K or CytK (Bacillus cereus) [9–15].

    The high population growth and the food marketing, have generated pathogens causing FBDs to be quickly transported, this has produced outbreaks in different regions, affecting the morbidity, mortality, and economy of the population involved. The trend seen in the United States, the United Kingdom, and Europe indicates that the incidence of FBDs is increasing; this will be a health problem in the following years [4, 16].

    There are different types of genus commonly associated with FBDs such as Campylobacterspp., enterotoxigenic E. coli(ETEC), enteropathogenic E. coli(EPEC), Salmonellaspp., Shigellaspp., Shiga toxin-producing E. coli(STEC) and V. cholerae[4, 17].

    A total of 66% of foodborne diseases is caused by bacteria. Major diseases include botulism caused by C. botulinum, gastroenteritis caused by E. colistrains, Salmonellosis and Staphylococcal poisoning. Moreover, B. cereusand V. choleraeare bacteria frequently reported as causative agents of toxicoinfection by food [18, 19].

    In some countries, food poisoning caused by S. aureusis the most prevalent; reports indicate that S. aureuscan be responsible for up to 41% of food poisoning outbreaks. Although it can affect people of any age, the range with the highest incidence goes from 20 to 49 years of age, where up to 48% of the cases can be concentrated. The main food products related to food poisoning caused by S. aureusare chicken and eggs, cakes, pastas, sauces, milk, and its derived products [20].

    Globally, the highest number of cases is caused by ETEC, 233 million cases, and Shigellaspp., 188 million cases; however, the highest numbers of deaths are caused by EPEC, 121,455 deaths; ETEC, 73,041 deaths, and Shigellaspp., 64,993 deaths. In total, 40% of the cases and 43% of the deaths caused by FBDs occurred in children under the age of 5 years old [17].

    Food poisoning caused by B. cereuscan occur any time of the year; it does not present a defined geographical distribution, and because it is naturally found in the environment, its distribution in various types of food occurs easily, especially in those of plant origin such as cereals and rice. Reports about food poisoning outbreaks caused by B. cereusare underestimated due to the lack of diagnostic tools; however, globally, there are figures where food poisoning caused by this pathogen occupies from 1 to 17.5% of the total cases of food poisoning caused by bacteria [21, 22].

    Food poisoning caused by C. botulinumis less frequent and the epidemiological information about it is scarce; outbreaks of food poisoning caused by this pathogen usually include members of one family, that is, they do not involve a large number of individuals and the main cause of such outbreaks is the consumption of canned food at home [23, 24].

    Food poisoning caused by C. perfringensoccurs at any time of the year, but it is more frequent in the last months of the year. It does not present a geographical distribution; in some countries like the United States, the outbreaks caused by this pathogen occupy the second place in foodborne diseases. Generally, this type of outbreaks affect a large number of individuals, therefore, they have a high range of morbidity. In total, 90% of the cases are caused by the intake of meat and poultry products; the contamination of meat and other food products occurs by the contact of pipelines with feces or contaminated surfaces [24, 25].

    Nevertheless, the distribution of pathogens varies depending on the region, due to cultural and economic factors that allow both incidence and mortality to be different for each pathogen associated with FBDs. For example, in Europe, Campylobacterand Salmonellaare reported pathogens; their reservoirs are livestock and domestic animals, and food contamination is produced due to bad practices in the food production chain and by cross-contaminations; however, although they play an important role in enteric diseases, they are less frequent than in countries defined by the World Health Organization (WHO) as high-mortality countries (Western Pacific Region and Africa Region), where the sanitary conditions and food and water contamination are factors that increase the incidence and mortality of these genera [17].

    In 2010, WHO wrote a report about the main pathogens involved in FBDs, dividing all countries in regions; these regions were grouped based on adult and infant mortality (Figure 1).

    Geographical distribution of countries by region. Subregions are defined on the basis of infant and adult mortality. Stratum/Layer A = very low infant and adult mortality; stratum B = low infant mortality and very low adult mortality; stratum C = low infant mortality and high adult mortality; stratum D = high infant and adult mortality; and stratum E = high infant mortality and very high adult mortality. AFR: African subregion, AMR: American subregion, EMR: Eastern Mediterranean, EUR: European subregion, SEAR: South-East Asian subregions, WPR: Western Pacific subregion. Adapted from World Health Organization [26].

    The risk group causing FBDs depends on the region, in developing countries such as African regions, South America, and South Asia, pathogens causing diarrheal diseases and the invasive pathogens causing infectious diseases and bacteria are the group that causes FBDs, followed by some cestodes and helminths; nevertheless, African regions, cestodes, and helminths are the group that causes FBDs because health and economic conditions limit proper food handling and preservation [17, 26].

    With the above, as each risk group is different for each region, in the same way, the distribution of the main pathogens involved in FBDs depends on each region, as well as their incidence; however, developing countries continue to show a great number of cases of FBDs. In addition, the prevalence of pathogens in these countries is higher than in developed countries (Figure 2) [4, 26].

    Global burden of FBDs by subregion (DALYS per 100,000 inhabitants) caused by major pathogens. DAYLs: Disability-adjusted life years metric, AFR: African subregion, AMR: American subregion, EMR: Eastern Mediterranean, EUR: European subregion, SEAR: South-East Asian subregions, WPR: Western Pacific subregion. Adapted from World Health Organization [26].

    Additionally, each region has different socioeconomic characteristics, this creates an impact on the incidence and the mortality of FBDs associated with different bacterial pathogens; the Shigellagenus occupies the first place in deaths in all regions; however, each region shows a different distribution among the genus that produce the highest number of deaths; this is due to the fact that medical care is different in each region, which means that in some regions a genus causes high mortality and in other regions it is only of medical relevance (Figure 3) [4, 17, 26].

    Median rate per 100,000 of diarrheal illnesses and deaths by region. The scale is on logarithmic basis 10. Adapted from Pires et al. [17].

    In accordance with the above, it is emphasized the importance of medical authorities to know the incidence of the pathogens causing FBDs that circulate in their regions; not only to know the morbidity and mortality rate, but also to provide the population with the appropriate medical care directed to the pathogen causing FBDs.

    The main risk factor involved in bacterial food poisoning is food contamination by pathogenic bacteria that produce toxins; such contamination can occur at any time, that is, from the crop, in the case of vegetables or, just before eating them, due to the consumer’s manipulation; in this way, all the people living on the earth are susceptible to food poisoning. Therefore, food poisoning is a worldwide public health problem, generally the most affected are children, the elderly, pregnant women, and immunocompromised people. As expected, individual factors such as age, gender, place of residence, socioeconomic factors, among others, are crucial in food poisoning acquisition and development [27–29].

    Food contamination can occur from primary production to the final consumer, consequently, there are different contamination risks according to the practices carried out in the different stages such as agricultural, livestock, and fish production; industrialization (in the case of processed food); marketing (points of sale), and transportation to the final consumer (homes, community dining rooms, and restaurants) [30].

    During the primary production, producers should consider the particular characteristics of the environment where they grow or breed and reproduce livestock, by applying measures to prevent any pollution caused by the air, water, or natural fertilizers. In general, the main risk of contamination in primary production is the unsafe agricultural practices such as the use of manure as natural fertilizer and irrigation with sewage, which violates the fundamental principle of preventing, at all costs and contamination of raw materials from fecal matter [31, 32].

    Additionally, another important factor to ensure food safety and good quality is the adequate control of time and temperature when cooking, processing, cooling, and storing food. To achieve a good control of such parameters, it is necessary to consider the physical, chemical, and microbiological characteristics of each type of food, for example, water activity, pH and type, and the initial number of microorganisms presented there. Similarly, other aspects need to be taken into account such as shelf life and usage, that is, whether it is a raw, processed, packaged, or ready-to-eat food [33, 34].

    Microbiological contamination can occur through direct contact or through air, utensils, contact surfaces, or the handler’s hands; therefore, ready-to-eat foods must be separated in space and time from raw or unprocessed foods. In addition, the latter must always be washed or disinfected. In all stages of the food chain, it is indispensable to use water; hence, this could be the main source of food contamination. It is then necessary to control and monitor the type and the source of the water used at each stage; however, when it is used for food handling, water has to be drinkable water that meets the physical, chemical, and microbiological criteria that its name requires [29, 31, 35].

    In terms of facilities, it is important to establish and monitor systems that ensure their maintenance, cleaning, and sanitation. These systems also include an adequate waste management and an effective pest control. The latter constitute a potential risk of any type of contamination; that is why it is necessary to implement measures that prevent the entrance of any type of pests, as well as measures to avoid their nesting and proliferation. Finally, pest eradication must be carried out by any physical, chemical, or biological method that does not represent a threat to health and food safety [27, 31].

    Within the food chain, food transportation plays an important role in preventing contamination and proliferation of microorganisms in food; thus, it is necessary to consider measures to prevent any type of contamination and to provide an environment to control the proliferation of pathogenic microorganisms and the production of bacterial toxins. Some important factors to consider during food transportation are temperature, direct exposure to sunlight, humidity, and airflows. At this stage, the type of containers and the type of packaging also play an important role; the aforementioned and transport conditions should be chosen based on the characteristics of the food that is being transported [36].

    Another important measure is the information that producers and suppliers offer to consumers regarding the characteristics and proper handling of prepackaged foods; this is why, generally, food must be packaged and labeled in such a way that the consumer has enough information to handle, store, and prepare the products appropriately without threatening his or her health. Labels should also include a batch number allowing rapid identification and market recalls of products potentially being dangerous for human consumption [37, 38].

    In general, microorganisms, more specifically bacteria, can proliferate under very different conditions; that is why they can be found in any type of environment. Even though bacteria are good at adapting to the environments they are in, there are certain conditions that promote bacterial growth more than others. These conditions include food, humidity, acidity, temperature, time, and oxygen; all of these are grouped in what is known as FATTOM (Food, Acidity, Time, Temperature, Oxygen, and Moisture). Knowing and avoiding these optimal conditions can help to prevent bacterial growth, bacterial infections, and food poisoning [39–41].

    Most foods contain nutrients required for microbial growth, which makes them easy targets for the microorganisms to develop; therefore, perishable. To reduce the breakdown of food and to prevent foodborne diseases, the proliferation of microorganisms under certain conditions must be controlled, as well as the conditions that must be used to reduce food spoilage to lengthen the time during which physicochemical and organoleptic characteristics must be kept under minimum acceptance parameters. Factors affecting the proliferation rate of microorganisms can be considered as intrinsic and extrinsic [42, 43].

    Intrinsic factors affecting the proliferation rate are more related to the internal characteristics of food products, and the way in which these characteristics maintain or affect the growth of microorganisms; these factors include water activity, pH, oxidation-reduction potential, content and type of nutrients, inhibiting substances, and biological structures [44, 45].

    It is defined as the amount of water available for the growth of microorganisms; microbial proliferation decreases when water availability also decreases. The water available for metabolic activity determines the degree of microbial growth instead of the total moisture content. The unit of measurement for the water that microorganisms require is usually expressed as water activity (Aw), which is defined as the water vapor pressure of food substrate, divided by the water vapor pressure of pure water, at the same temperature. This concept is related to relative humidity (RH), thus: RH = 100 × Aw. The approximate optimal Aw for the growth of most microorganisms is 0.99; most bacteria require an Aw greater than 0.91 to grow. Gram-negative bacteria require higher values than Gram-positive bacteria. Most of the natural food products have an Aw of 0.99 or more. Generally, bacteria have the highest requirements of water activity, fungi have the lowest, and yeasts have intermediate requirements. Most bacteria that decompose food do not grow with an Aw less than 0.91, but fungi and yeasts can grow with values of 0.80 or less, including surfaces partially dehydrated. The lowest value reported for bacteria in food is 0.75 for halophytes, while xerophilic fungi and osmophilic yeasts have shown growth at Aw values of 0.65 and 0.61, respectively [46, 47].

    The pH is defined as the negative logarithm of hydronium ions concentration; it is considered as a unit of measure to establish acidity or alkalinity levels of a substance, in this case food, and it is determined by the number of free hydrogen ions (H+). The effects of adverse pH affect at least two aspects of the microbial cell-functioning of its enzymes and nutrients transportation to the cell.

    The cytoplasmic membrane of microorganisms is relatively impermeable to H+ and OH− ions; its concentration in the cytoplasm remains reasonably constant, despite the wide variations that may occur in the pH of the surrounding medium. When microorganisms are in an environment below or above the neutral level, their ability to proliferate depends on their ability to change the environmental pH to a more appropriate range, since key components like DNA or ATP require a neutral medium [42, 43, 47].

    The pH for the optimal growth of most microorganisms is close to neutrality (pH = 6.6–7.5). Yeasts can grow in an acid environment and thrive in an intermediate range (4.0–4.5), although they survive in values between 1.5 and 8.5. Fungi tolerate a wide range (0.5–11.0), but their growth is generally higher in an acid pH (too acid for bacteria and yeast). Bacterial growth is usually favored by pH values closer to the neutral level. Nevertheless, acidophilic bacteria grow on substrates with a pH of up to 5.2 and below that point the growth reduces dramatically [42, 48].

    In general, fruits, vinegars, and wines have pH values lower than those required for bacterial growth, so they can usually be decomposed by fungi and yeasts. Most vegetables have pH values lower than those from fruits, and consequently, vegetables are more exposed to bacterial or fungi decomposition. In contrast, most meats and sea products have pH values equal or greater than 5.6, making them susceptible to decomposition by bacteria, fungi, and yeasts [44, 48, 49].

    The oxidation-reduction potential (O/R) is an indicator of the oxidizing and reducing power of a substrate; that is, the O/R potential of a substrate can be generally defined as the ease with which a substrate loses or gains electrons (when a food product loses electrons, it oxidizes, whereas, when it gains electrons it is reduced; thus, a food product that easily gives electrons is a good reducing agent and the one that receives electrons is a good oxidizing agent). To achieve optimum growth, some microorganisms require reducing conditions and others require oxidizing conditions. The O/R potential of a system is expressed with the Eh symbol (when electrons are transferred from one compound to another, a potential difference is created between the two compounds; this difference can be measured and expressed as millivolts [mV]). The more oxidized a substance is, the more positive the electrical potential will be; and the more reduced a substance is, the more negative the electrical potential will be. When the concentration of oxidant and reducer is equal, there is an electrical potential of zero [39].

    Saprophytes that are capable of transferring hydrogen as H+ and e− (electrons) to molecular oxygen are aerobic; that is, aerobic microorganisms require positive Eh values (oxidized) for their growth, whereas anaerobic microorganisms require negative values of Eh (reduced). Facultative microorganisms can grow under any of the conditions. It has to be considered that maximum and minimum Eh values (in mV) necessary for aerobic and anaerobic growth could be lethal to the other group. Among food substances that help to maintain reducing conditions are the –SH groups in meats and the ascorbic acid, as well as, reducing sugars in fruits and vegetables. Some aerobic bacteria grow better under slightly reducing conditions being known as microaerophiles such as Lactobacillusand Campylobacter. Most of fungi and yeasts found in food are aerobic, although a few tend to be facultative anaerobes. Regarding the Eh value of food, vegetables, especially juices, tend to have Eh values of +300 to +400 mV; so, it is not surprising to find that aerobic bacteria and fungi are the common cause of decomposition in this type of products. Meats have Eh values around −200 mV; in ground meats, Eh is usually around +200 mV. Various types of cheese show Eh values between −20 and −200 mV [46].

    Microorganisms have nutritional requirements, most of them need external sources of nitrogen, energy, minerals, as well as vitamins, and related growth factors; these requirements are found in our food, so if they have the right conditions to develop, they will. In general, fungi have the lowest nutrient requirement, followed by Gram-negative bacteria, then yeasts and finally, Gram-positive bacteria, which have the highest requirements [46, 50].

    The primary sources of nitrogen used by heterotrophic microorganisms are amino acids. A great number of other nitrogen compounds may serve for this function for several types of organisms. For example, some of them can use free nucleotides and amino acids, while others can be capable of using peptides and proteins. In general, simple compounds like amino acids will be used by almost all of the organisms before attacking more complex compounds such as high molecular weight proteins. The same applies to polysaccharides and lipids [39, 51].

    Microorganisms in food tend to use as energy sources, sugars, alcohols, and amino acids. Fungi are the most efficient in the use of proteins, complex carbohydrates, and lipids because they contain enzymes capable of hydrolyzing these molecules into simpler components; many bacteria have a similar capacity, but most yeasts require simpler molecules. All microorganisms need minerals, although vitamin requirements vary. Fungi and some bacteria can synthesize enough B vitamins to meet their needs, while others need to have a source of vitamins, food products being an excellent source of them [39, 50].

    Gram-positive bacteria are the ones that have lower synthesized capacity, so they need one or more of these components to grow. In contrast, Gram-negative bacteria and fungi are capable of synthesizing the most, if not all, of their requirements and consequently, these two groups of organisms can grow in food products with low content of B vitamins [46, 52, 53].

    Food factors are very important for the development of microorganisms; there are external or extrinsic factors. This term refers to environmental factors that affect the growth rate of microorganisms; these factors include temperature, oxygen availability, and relative humidity, as well as, the presence and activities of other microorganisms [46].

    Microorganisms have an optimal range, as well as a minimum and maximum temperature to grow. Therefore, ambient temperature determines not only the proliferation rate, but also the genera of microorganisms that are going to be developed, along with the microbial activity degree that is registered. The change in only a few degrees in temperature will favor the growth of completely different organisms, and it will result in a different type of food decomposition and/or foodborne disease. Due to these characteristics, thermal treatment is employed as a method to control microbial activity [46, 54].

    The optimal temperature for the proliferation of most microorganisms ranges from 14 to 40°C, although some genera develop below 0°C, and other genera grow at temperatures above 100°C. Nevertheless, food quality must be taken into account when selecting storage temperature. Although it can be desirable to storage all food products at temperatures equal or less to those of refrigeration, this is not the best thing to do to maintain a desirable quality in some food products such as banana, whose quality is best maintained in storage at 13–17°C than at 5–7°C. Similarly, many vegetables are favored at temperatures near 10°C such as potatoes, celery, cabbage, and many others. In each case, the success of storage temperature depends, to a large extent, on the relative humidity and the presence or absence of gases such as carbon dioxide and ozone [46, 55].

    Like temperature, the oxygen availability determines the microorganisms that will be active. Some have an absolute requirement for oxygen, while others grow in total absence of it, and others may grow with or without oxygen. Microorganisms that require free oxygen are called aerobic microorganisms, while those that thrive in the absence of oxygen are called anaerobic; and those that grow both in presence or absence of free oxygen are known as facultative microorganisms [43, 46, 56].

    Carbon dioxide is the most important atmospheric gas that is used to control food microorganisms. Along with oxygen, it is used in packaged food with modified atmosphere. Ozone is another atmospheric gas with antimicrobial properties, and for decades, it has been used as an agent to lengthen shelf life of certain types of food. Although being effective against a variety of microorganisms, it is a highly oxidizing agent;thus, it cannot be used in food products with high lipid content, as it could accelerate rancidity. Normally, ozone levels of 0.15–5.00 ppm in the air inhibit the growth of some bacteria that decompose food as well as yeast growth [46, 57].

    Relative humidity (RH) of the environment is important from the point of view of water activity within food and the growth of microorganisms on surfaces. This extrinsic factor affects microbial growth and can be influenced by temperature. All microorganisms have a high-water requirement, this being needed for their growth and activity [46, 54].

    When the Aw of a food product is set at 0.60, it is important that this food is stored under RH conditions that do not allow food to draw humidity from the air and, therefore, it increases its own Aw from the surface and subsurface to an extent where microbial growth can occur. A high relative humidity can cause humidity condensation in food, equipment, walls, and ceilings. Condensation causes wet surfaces, which lead to microbial growth and decomposition. Microbial growth is inhibited by a low relative humidity. When food products with low Aw values are placed in high RH environments, food takes in moisture until they reach balance. Similarly, food products with high Aw lose moisture when placed in an environment with low RH. There is a relationship between RH and temperature that must be taken into account when selecting the appropriate storage environments for food products. Overall, the higher the temperature, the less the RH, and vice versa [46, 54, 58].

    Bacteria require higher humidity than yeasts and fungi. The optimal relative humidity for bacteria is 92% or higher, while yeasts prefer 90% or higher, and fungi thrive if the relative humidity is between 85 and 90%. Food products suffering superficial decomposition by fungi, yeasts, and specific bacteria, should be stored under low RH conditions. Poorly packed meats such as whole chickens and beef cuts, tend to suffer a lot of superficial decomposition inside the refrigerator before internal decomposition occurs, usually, due to high RH in refrigerators, and to the fact that the biota decomposing meat is essentially aerobic in nature [46, 59].

    Although it is possible to decrease the possibility of superficial decomposition in certain food products by storing them in low RH conditions, it should be remembered that the food itself will lose moisture into the atmosphere under such conditions, and thus, it will become undesirable. When selecting appropriate RH conditions, there should be taken into account both the possibility of superficial microbial growth and the quality that the food product needs to have. By altering the gas atmosphere, it is possible to delay superficial decomposition without lowering the relative humidity [46, 60].

    Some food origin organisms produce substances that can inhibit or be lethal for other organisms; these include antibiotics, bacteriocins, hydrogen peroxide, and organic acids. Bacteriocins produced by lactic acid-producing bacteria originated in various food products such as meat, are of high interest. Bacteriocins produced by Gram-positive bacteria are biologically active proteins with bactericidal action. Some bacteriocins produced by these bacteria inhibit a variety of food pathogens including, B. cereus, C. perfringens, Listeriaspp., A. hydrophila, and S. aureus, among others [39, 46].

    Normally food products can reach the final consumer at home, in community dining rooms, or restaurants. Measures to prevent food poisoning should be implemented at these locations, particularly in areas where large volumes of food are distributed such as cold chain, frozen chain, hot chain, and vacuum cooking. Likewise, in the frozen chain, food temperature is gradually lowered to −18°C and defrosted at temperatures higher than 65°C at the time it will be served to the costumer (not before); while in the hot chain, for example, in a buffet, food is kept at temperatures higher than 65°C and it should be consumed within 12 h maximum [61].

    Other important measures are the use of food preservation methods, which can be physical or chemical. Within the physical methods, there are the traditional or industrial pasteurization, dehydration, preservation in modified atmosphere, and irradiation. In order to maintain an adequate quality control and to minimize the risk of food poisoning, microbial markers can be used; these markers do not represent a potential health risk, however, a large number of them indicate deficiencies in hygiene and sanitary quality of food products; it also leads to a decrease in the shelf-life and could be related to the presence of pathogenic microorganisms. The main microbial markers are aerobic mesophilic, total coliforms, fecal coliforms, Enterococci, E. coli, S. aureus, and lactic acid bacteria [62].

    Once the risk factors are identified, it is necessary to establish a system that allows to prevent and decrease all of them; to do this, a method with scientific basis and systematic profile has been established, this is known as Hazard Analysis and Critical Control Point (HACCP). A microbiological approach should consider the type of microorganism or metabolite (toxins) that threatens human health; the analytical methods for its detection and quantification; the number of samples to be taken and the size of the analytical unit; and the microbiological limits considered to be adequate at specific points in the food chain [63].

    In food products, we can find different types of toxins such as, bacterial, fungal (mycotoxins), algae or plant toxins, as well as metals, toxic chemicals (zinc, copper, and pesticides), and physical contaminants that can cause diseases in people who eat them; all of these can cause the well-known “foodborne diseases” [64].

    Foodborne diseases can be classified into two groups: poisoning and infection.

    Poisoning is caused by the intake of chemical or biological toxins; or toxins produced by pathogens, the latter can be found in food, even if the bacterium is not there.

    Infection is caused by the intake of food containing viable pathogens. Furthermore, a toxic infection (toxicoinfection), formerly known as a toxin-mediated infection, is caused by eating food with bacteria that grow and produce a toxin inside the body [18, 64–66].

    To meet the ideal conditions, microorganisms in food grow and produce toxins. By ingesting contaminated food, toxins are absorbed through the intestinal epithelial lining, and it causes local tissue damage. In some cases, toxins can reach organs such as the kidney or the liver, the central nervous system or the peripheral nervous system, where they can cause some damage [18].

    The most common clinical symptoms of foodborne diseases are diarrhea, vomit, abdominal cramps, headaches, nausea, pain, fever, vomit, diarrhea with mucus and blood (dysentery), and rectal tenesmus. Some of the microorganisms causing foodborne diseases, either from poisoning, intoxication or toxicoinfection are described in Tables 2–4. These diseases are generally diagnosed based on the patient’s clinical record or their symptoms [18–20].

    Pathogens that cause infection.

    Modified from Refs: [18–20].

    Pathogens that cause intoxication.

    Source: Modified from Refs: [18–20].

    Pathogens that cause toxico-infection.

    Source: Modified from Refs: [18–20].

    Toxins produced by pathogens involved in foodborne diseases have different characteristics, some of them are shown in Table 5 [9, 11–15, 67].

    Main toxins produced by pathogens involved in foodborne diseases and their biological effect.

    Note: A-5B indicates that the subunits are separately synthesized but associated by noncovalent bonds during secretion and binding to target. 5B indicates that the binding domain of the protein is composed by five identical subunits. A/B denotes a toxin synthesized as a simple polypeptide divided into domains A and B that can be separated by proteolytic cleavage. HBL: hemolysin BL, NHE: nonhemolytic enterotoxin.

    Source: Modified from Refs: [9, 11–15, 67].

    This section will be addressed to some diseases caused by consuming food contaminated with bacterial toxins or microorganisms that produce them. Among some of the most important diseases are the ones transmitted by V. cholerae, S. aureus, B. cereus C. perfringens, C. botulinum and Listeria monocytogenes.

    V. choleraehas a free life cycle, it is ubiquitous in aquatic environments; it is able to remain virulent without multiplying in fresh water and sea water for a long time. They are more frequent in temperate waters and can be isolated in seafood and fish. The most notable species are V. choleraeO1 and O139, causative serogroups of Cholera. Non-O1 strains and the rest of the species cause cholera-like diarrheal syndromes, but they are not as severe, although they frequently produce extraintestinal infections [68–70].

    The CTX toxin (Cholera toxin) is the main virulence factor of V. choleraeO1 (Ogawa, Inaba, and Hikojima serotypes, Classical and El Tor biotypes) and O139; it contributes to cause profuse diarrhea, after an incubation period from 2 h to 5 days; stools have the appearance of rice water, there is dehydration and electrolyte imbalance, which can lead to death. Approximately 75% of the infected people are asymptomatic, that is, they do not develop the symptoms aforementioned; however, the pathogen is shed in their feces for 7–14 days, which is a very serious source of contamination since it is possible to infect others. The most vulnerable groups are children, adults, and people infected with the HIV virus [68, 69, 71].

    This toxin can be identified by the presence of the ctxABgene. V. choleraeno-O1 has the ctxgene but it is rarely expressed; nevertheless, a faster test is not yet available, although the WHO is currently in the process of validating new rapid diagnoses. The bacteria can be isolated and identified from stool samples by using laboratory procedures [24, 69, 71].

    Efficient treatment resides in prompt rehydration through oral solutions or intravenous fluids. The use of antibiotics is suggested only when there is severe dehydration. The supply of safe drinking water, the adequate sanitation, and food security are essential to prevent the emergence of Cholera. Moreover, vaccines administration has emerged because control measures to prevent contamination are insufficient; this is the reason why oral vaccines have been developed as tools to prevent outbreaks. These vaccines are given to more vulnerable populations in areas where the disease is endemic. Experience in different mass vaccination campaigns in countries such as Mozambique, Indonesia, Sudan, and Zanzibar clearly indicates that vaccination requires careful and early planning and preparation, and therefore, it cannot be improvised at the last minute [71].

    The lack of toxicity combined with stability and the relative ease to express the Cholera Toxin Subunit B (CTB) has contributed to be an easily manageable adjuvant. The ability to express protein in a wide variety of organisms broadens even further its application potential. CTB is currently being used in vaccines such as Dukoral, a vaccine against V. choleraethat consists of dead bacteria and recombinant CTB. It has been approved as adjuvant for vaccines in Europe and in Canada; and given the excellent adjuvant effect, this protein is likely to play an important role in vaccine formulation in the future [72].

    Staphylococcal foodborne illness is one of the most common diseases acquired by S. aureus. It is one of the most concerned diseases by public health programs in the world; it is due to the production of one or more toxins by the bacteria during their growth at permissive temperatures; however, the incubation period of the disease depends on the amount of ingested toxin. Small doses of enterotoxins can cause the disease; for example, a concentration of 0.5 ng/mL in contaminated chocolate milk has been reported to cause large outbreaks [73].

    S. aureusproduces various toxins. Staphylococcal enterotoxins are a family of nine thermostable enterotoxin serotypes belonging to a large family of pyrogenic toxins (superantigens). Pyrogenic toxins can cause immunosuppression and nonspecific T cell proliferation. Enterotoxins are highly stable and they resist high temperatures (which makes them suitable for industrial use) and environmental conditions of drying and freezing. They are also resistant to proteolytic enzymes (pepsin and trypsin) at low pH, enabling them to be fully functional in the digestive tract after infection [73].

    The mechanism by which poisoning is caused is not entirely clear yet. However, enterotoxins have been observed to directly affect the intestinal epithelium and the vagus nerve causing stimulation of the emetic center. It is estimated that 0.1 μg of enterotoxin can cause staphylococcal poisoning in humans. Apart from causing poisoning, S. aureuscan also cause toxic shock syndrome due to the production of the Toxic Shock Syndrome Toxin 1 (TSST-1) and Enterotoxin Type B [65, 73, 74].

    Symptoms include nausea, vomit, abdominal cramps, salivation, diarrhea could be present or absent. The first three symptoms are the most common ones. Usually, it is a self-limiting disease and can be cured in 24–48 h, but it can become severe, especially in children, the elderly, and immunocompromised people. Toxic shock syndrome is characterized by high fever, hypotension, erythematous rash (similar to scarlet fever, peeling of the skin during recovery, flu-like symptoms, vomiting, and diarrhea) [73–75].

    The diagnosis of the disease is carried out by detecting the staphylococcal enterotoxin in the food or by recovering at least 105S. aureus/g from food leftovers. The enterotoxin can be detected by several methods: bioassays, molecular biology, and immunological techniques. The isolated strains can be genetically characterized by multilocus sequences from the spaor SCCmecgene, and pulsed-field electrophoresis [73].

    The mainly involved food products in outbreaks and where S. aureuscan grow optimally, since they are stored at room temperature, are meat and its derived products, poultry and eggs, milk and its derived products, salads, and bakery products (cream-filled cakes and stuffed sandwiches) [65, 73].

    Other factors that must be taken into account are the emergence of methicillin resistant strains, which may be found in food (mainly in meat and milk). It is important to note that many of the isolates obtained from outbreaks are not tested for antimicrobial susceptibility; due to the various problems that these strains can create, the antimicrobial susceptibility test should be performed. They have been reported to be causative agents of outbreaks in blood infections and wounds in immunocompromised patients in hospitals [65, 73].

    Foodborne illness due to S. aureusmay be preventable. It is known that the permissible temperature for the growth and production of the enzyme is between 6 and 46°C; thus, food products could be cooked above 60°C and refrigerated below 5°C. Therefore, maintaining the cold chain of food can prevent the growth of the microorganism. By using good manufacturing practices and good hygiene practices, the contamination by S. aureuscan be prevented [73].

    B. cereusis a ubiquitous microorganism in the environment, and it can easily contaminate any food production and processing system, due to the formation of endospores. The bacterium can survive pasteurization and cooking processes [11, 15].

    It has been demonstrated that this microorganism produces, cereulide or emetic toxin; three enterotoxins, hemolysin BL (HBL), nonhemolytic (NHE), cytotoxin K (CytK), which are responsible for the emetic syndrome and diarrhea; and three phospholipases, phosphatidylinositol hydrolase, phosphatidylcholine hydrolase, and hemolytic sphingomyelinase. Cereulide is a thermostable cyclic peptide that causes emesis by stimulating the afferent vagal pathway through its bond to the serotonin receptor. The toxin is produced during the stationary phase of growth of the microorganism and it accumulates in food over time. The structure of the toxin explains its resistance to food processing methods. In contrast, inside the small intestine of the host, the thermolabile enterotoxins, HBL and NHE, produced during the exponential phase of the vegetative growth of the bacterium are the cause of diarrheal syndrome; the proteins that form enterotoxins (binding and lithic factors) are unable to traverse intact the gastric barrier; that is why it is considered that preformed or extracellular enterotoxins in food are not involved in the pathogenesis of the bacterium. It is believed that the spore germination that reaches the small intestine, the growth, and the simultaneous production of the enterotoxin are the ones that cause diarrhea. HBL is a hemolysin formed by three components, two protein subunits (L2 and L1), and one B protein; it has hemolytic, cytotoxic, and dermonecrotic effect, and it induces vascular permeability. NHE also consists of three components: NheA, NheB, and NheC. It has been demonstrated that strains producing emetic toxin do not produce enterotoxin. The cytotoxin K is similar to the Alpha-toxin of S. aureusand the Beta-toxin of C. perfringens[13, 15, 76].

    Furthermore, the enterotoxin FM (EntFM) has been described; it is a 45 kDa polypeptide encoded by the entFMgene, located in the bacterial chromosome. It has not been directly involved in food poisoning; however, the presence of the gene in strains that cause diarrheal outbreaks has been detected; in experiments with mice and rabbits, it causes vascular permeability [11].

    The emetic syndrome is characterized by nausea and vomit similar to those produced by S. aureuspoisoning. Symptoms appear soon after consuming food contaminated with the preformed toxin. Generally, poisoning develops with mild symptoms, usually lasting no more than 1 day, but severe cases require hospitalization. The diarrhea that is caused belongs to the secretory type, similar to the one produced by V. cholerae. Colic pain occurs similar to that of C. perfringenspoisoning. Both syndromes are self-limiting [13, 15, 77].

    Enterotoxins can be detected by immunoassays or molecular biology (conventional PCR and multiple PCR) by looking for the cesgene (nonribosomal production of cereulide); by detecting the hblD, hblC, and hblAgenes encoding the L1, L2, and B protein components of the HBL toxin, respectively; or the nheA, nheB, and nheCgenes of the NHE toxin components. The 16Sribosomal gene can be looked for by real-time PCR [11, 13, 77].

    Apart from causing food poisoning, B. cereuscan also cause local and systemic infections in immunocompromised patients, neonates, people taking drugs, and patients with surgical or traumatic wounds, or catheters [15].

    The most susceptible food products to be contaminated include flours, meats, milk, cheese, vegetables, fish, rice and its derived products; generally, in food with high content of starch. The strains produced by the emetic toxin grow well in rice dishes (fried and cooked) and other starchy products; although, there have been studies where it has been demonstrated that the toxin can be in different types of food products; while strains producing diarrheagenic toxins grow in a wide variety of food products, from vegetables to sauces and stews [15, 77].

    Strains isolated from infections have been shown to be sensitive to chloramphenicol, clindamycin, vancomycin, gentamicin, streptomycin, and erythromycin; they are resistant to β-lactam antibiotics, including third-generation cephalosporins [15].

    Inadequate cooking temperatures, contaminated equipment, and poor hygiene conditions at the food processing and preparation sites are the major factors that contribute to food poisoning by B. cereusand its toxins; that is why, it is suggested to store food at temperatures lower than 4°C or to cook them at temperatures higher than 100°C, and to reheat or cool food rapidly, to avoid prolonged exposure to temperatures that allow spore germination and to diminish the risks of a possible poisoning [11].

    C. perfringensis an anaerobic bacterium that creates spores that survive in soil, sediments, and areas subject to both human and animal fecal contamination. It is widely distributed in the environment and is frequently found in the human intestine and in several domestic and wild animals’ intestines [78].

    C. perfringensis classified into five groups (A, B, C, D, and E), due to the different toxins it produces (alpha, beta, epsilon, and iota). The Alpha-toxin is produced by all the five groups. The Beta-toxin forms selective pores for monovalent ions in the lipid bilayers, functioning as a neurotoxin capable of producing arterial constriction. The Epsilon-toxin is the most potent clostridial toxin after tetanus and botulinum neurotoxins (BoNTs). It is produced and secreted by a prototoxin that acquires its maximum biological activity by undergoing a specific proteolytic cleavage; its activation can be catalyzed by trypsin, chymotrypsin, and a zinc metalloprotease [12].

    The toxin receptor is unknown, but it is known to be a surface protein anchored by glycosylphosphatidylinositol. Its main biological activity is the edema generation; it is lethal but not hemolytic. The Iota-toxin is a member of the binary toxin family, since it is formed by a binding peptide (Ib) necessary for the internalization of the enzymatic peptide (Ia; ADP-ribosyltransferase). Proteolytic removal of a propeptide fragment is required to allow Ib to be inserted into the membrane and to interact with Ia. Ib, when inserted into the membrane, forms a heptameric pore that allows the exit of K+ and Na+ ions, and the entry of Ia, which once inside the cell, is ribosylated by the G-actin; it depolymerizes the filaments of Actin by destroying the cellular cytoskeleton. The Iota-toxin is dermonecrotic, cytotoxic, enterotoxic, and induces intestinal histopathological damage [12].

    However, the virulence of this bacterium is not only due to the presence of these 4 toxins; there have also been described 15 toxins within which the CPE enterotoxin is responsible for causing diarrhea in humans and animals, and it is produced by Type A strains. This toxin is associated with 5 or 15% of gastrointestinal diseases in humans different from food poisoning such as diarrhea produced by antibiotics; the NetB toxin is frequently related to necrotic enteritis in birds and the Beta2-toxin is apparently associated with enteritis. The production of toxins in the digestive tract is associated with sporulation. The disease is foodborne; and only one case has implied the possibility of poisoning caused by the preformed toxin [12, 78, 79].

    C. perfringenscauses food poisoning characterized by severe abdominal cramps and diarrhea beginning after 8–22 h of food intake, the disease ends 24 h after the intake; although, in some cases the disease may persist for 1–2 weeks. Additionally, there is a more severe but less frequent disease caused by eating a food product contaminated with type C strains; this disease is known as necrotic enteritis or pig-bel disease, and it is often fatal. Deaths caused by necrotic enteritis are due to intestinal infection and necrosis, as well as by septicemia, the elderly people being the most affected population [78].

    The disease diagnosis is confirmed by the presence of the toxin in the stools of patients; either by traditional methods (culture from the stools or the food involved) or by molecular methods by looking for the following genes: cpe(CPE toxin), plc(Alpha-toxin), and etx(Epsilon-toxin) [12, 78, 79].

    Among the main food products involved are meat and its derived products. The disease can be prevented if the food has been properly cooked; although, there may be a risk of cross-contamination if the cooked food comes in contact with raw and contaminated ingredients, as well as contaminated surfaces [78].

    There is no specific treatment or established cure for the infections caused by the toxins of the bacteria. Supportive care includes administration of intravenous fluids, oral rehydration salts solutions, and medication for fever and pain control. The treatment of gas gangrene is based on surgical measures with debridement and removal of the affected tissue and administration of high doses of antibiotics. Necrotizing enterocolitis is treated systemically with penicillin G, metronidazole or chloramphenicol; 50% of the cases require surgical treatment in which a segmental jejunum resection is performed. The antibiotics active against anaerobic bacteria are effective; however, there are strains resistant to penicillin and clindamycin, therefore, it is suggested to perform antimicrobial susceptibility tests, especially in patients with severe disease and those requiring long-term treatments [9, 80].

    C. botulinumis a spore-forming microorganism; these spores can remain viable for long periods of time when the environmental conditions are absolutely unfavorable for the development of the microorganism [60].

    Four groups are recognized in C. botulinum, as well as seven antigenic variants of botulinum neurotoxins (A–G). Groups I and II are primarily responsible for botulism in humans; Group III is responsible for causing botulism in several animal species, and Group IV appears not to be associated with the disease in either humans or animals. Group I is also known as C. botulinum-proteolytic (mesophilic microorganisms), while group II is known as C. botulinum-non-proteolytic (psychrophilic microorganisms). Group I forms spores that are highly resistant to heat, the “Botulinum cook” (121°C/3 min) given to canned foods with a low content of acid is designed to inactivate them; neurotoxins formed in this group are A, B, F, and H. Group II forms moderately heat-resistant spores, and the neurotoxins formed are B, E, and F. Botulism types A, B, E, and F rarely cause the disease in humans, whereas in animals it is caused by types C and D. Toxins are resistant to proteolytic reactions and to denaturation into the gastric apparatus. Botulinum toxins are metalloproteins with endopeptidase activity that require zinc; the general structure shows two chains with a molecular weight of 150 kDa, the double chain is subdivided into a heavy (H) structure constituted by a nitrogen terminal domain (HN), and a carboxyl-terminal (HC), and a lighter structure (L) that performs the catalytic function of the toxin. HC is responsible for binding to presynaptic receptors for internalization, and HN is called translocation domain [81–83].

    C. botulinum,is a bacterial species known simply for producing the botulinum toxin. The number of genes in Group II strains coding for the neurotoxin is variable; there may be one to three genes that encode one to three different neurotoxins; if there are two genes, there can be one active toxin and an inactive toxin, or both toxins can be active. In Group II, the presence of only one gene has been described, that is why there is only one neurotoxin; however, in other studies it has been demonstrated that in Type F strains the toxin has part of Type B and Type E neurotoxins. Botulinum neurotoxins form complexes with accessory proteins (hemagglutinin and nonhemagglutinin), which protect the neurotoxin and facilitate their adsorption into the host. The hemagglutinin complex of the neurotoxin type A specifically binds the cell adhesion protein, E-cadherin, by binding the epithelial cell and facilitating the adsorption of the neurotoxin complex from the intestinal lumen. Dual toxin-producing strains have been isolated from botulism in humans, the environment, and food; recently there have been found strains that produce three botulinum toxins called F4, F5, and A2. The significance of producing two or more toxins on virulence, as well as the evolutionary consequences are not yet clear. Phylogenetic studies show evidence of horizontal gene transfer; the production of the dual toxin in Group I and the production of a single toxin in Group II is still not clear. Therefore, studies with toxins isolated and purified from the different groups of C. botulinumare still being carried out [81–83].

    Botulism is a severe disease with a high fatality rate. The typical symptoms are flaccid muscle paralysis, sometimes it starts with blurred vision followed by an acute symmetrical decrease of bilateral paralysis that, if untreated, can lead to paralysis of the respiratory and cardiac muscles. If severe cases are not fatal, the patient may improve his/her condition after months or even years. There are three types of botulism: infant/adult intestinal botulism, wound botulism, and foodborne botulism. The first type (infant/adult intestinal botulism) is an infection associated with the multiplication of the microorganism and neurotoxin formation in the intestine; the second type (wound botulism) is an infection associated with cell multiplication and toxin formation in the wound, often acquired after drug abuse; and the third type (foodborne botulism) is a poisoning caused by the consumption of neurotoxin preformed in food. An amount of 30 ng of toxin is enough to cause the disease and sometimes death. Symptoms appear between 2 h and 8 days after the intake of contaminated food, although they may occasionally appear between 12 and 72 h [81, 82].

    Botulism can be diagnosed only by clinical symptoms, but its differentiation from other diseases can be difficult. The most effective and direct way of confirming the disease in the laboratory is by demonstrating the presence of the toxin in the serum, in stools of patients, or in food products consumed by them. One of the most sensitive and widely used methods to detect the toxin is through neutralization in a rodent. This test takes 48 h, and culture of specimens takes from 5 to 7 days. Infant botulism is diagnosed by detecting botulinum toxins and the microorganism in the stools of children [78].

    Approximately 90% of the reported cases are related to the consumption of home-made preserved food, especially vegetables; the industrial preparation of meat and fish is rarely associated with botulism. Food products where spores of the bacteria or the botulinum toxin can be found are canned corn, pepper, soups, beets, asparagus, ripe olives, spinach, tuna chicken, chicken liver, ham, sausages, stuffed eggplants, lobster, and honey, just to name a few [78, 82].

    To prevent the chances of getting botulism through food, it is necessary to carry out appropriate control measures in food processing and handling, especially when new technologies are introduced or modified. Applying the “Botulinum cook” in the modern industry allows to secure canned foods. The use of chlorine and chlorinated compounds can help sanitize places that handle food industrially. Spores can also be inactivated with ozone and ethylene oxide [81, 82].

    L. monocytogenesis a facultative intracellular microorganism widely distributed in nature, capable of surviving both in the soil and the cytosol of a eukaryotic cell. Considering somatic (O) and flagellar (H) antigens, this bacterium can be classified into 13 serotypes (1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, 4b, 4c, 4d, 4e, 7), but only the serotypes 1/2a, 1/2b, and 4b are responsible for more than 98% of the cases of human listeriosis. Furthermore, it has also been grouped into four lineages (I, II, III, and IV), where lineage I (serotypes: 1/2b, 3b, and 4b) and lineage II (serotypes: 1/2a, 1/2c, 3a, and 3c) include most strains isolated from clinical cases; lineage I strains have a greater pathogenic potential. Lineages III and IV include strains of serotypes 4a, 4c, and an atypical 4b [84].

    L. monocytogenesexpresses multiple virulence factors, which allow to enter and survive in several nonphagocytic cells. After cellular internalization, listeriolysin O (LLO) and two phospholipases mediate the escape of the bacterium from the endocytic vesicle into the cytoplasm, where the microorganism divides and submits the F-actin based on mobility to spread from cell to cell. The LLO (coded by the gene hly) is a cholesterol-dependent toxin; it is able to form pores in the membrane of phagosomes, allowing L. monocytogenesto escape from primary and secondary vacuoles. The cytolytic activity of LLO increases with the action of a phosphatidylinositol phospholipase C (PI-PLC), the substrate of which is phosphatidylinositol; and a phosphatidylcholine phospholipase C (PC-PLC), which is a lecithinase with enzymatic activity over phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine. PC-PLC is expressed as a protoenzyme and zinc-dependent metalloprotease Mpl is required for its maturation; so once free in the cytosol, the bacterium acquires the necessary nutrients for intracellular multiplication. Some studies have shown that LLO is a critical invasion factor, which perforates the plasma membrane of the host cell to activate the internalization of the bacterium in human hepatocytes. Moreover, other studies have shown that LLO fails to mediate the intracellular survival of L. monocytogenesin neutrophils, where early degranulation leads to the release of proteases such as matrix metalloproteinase (MMP)-8, degrading LLO and avoiding the perforation of the membranes [84–86].

    L. monocytogenescauses a severe infection known as listeriosis, which is usually acquired after the intake of food contaminated with the microorganism. The disease mainly affects pregnant women, newborns, the elderly, and immunocompromised people, so it is rare for the disease to occur outside the aforementioned groups. Listeriosis is a mild disease in pregnant women, but it is severe in fetus and newborns. People over 65 years of age or immunosuppressed people can develop infection in the bloodstream (sepsis) or in the brain (meningitis or encephalitis). Sometimes the infection can affect bones, joints, thorax, and abdomen. Listeriosis can cause fever and diarrhea similar to that caused by other foodborne microorganisms and is rarely diagnosed. Pregnant women with listeriosis have fever, fatigue, and muscle pain (flu-like symptoms). During pregnancy, the organism can cause miscarriage, stillbirth, premature labor, and infection in the newborn. In the other risk groups, the symptoms are headaches, neck stiffness, confusion, loss of balance, seizures, fever and muscle pain. People with invasive listeriosis usually develop symptoms from 1 to 4 weeks after ingesting food contaminated with the bacterium; although symptoms have been reported after 70 days of exposure or on the same day of the poisoning. The disease is usually diagnosed by culturing the bacterium from tissues or fluids such as blood, cerebrospinal fluid, or placenta. From food products, this microorganism can be detected by various methods such as the use of chromogenic media; immunological methods, although some are nonspecific; molecular methods (hybridization, PCR, and real-time PCR); microarrays or biosensors; and also specific commercial methods. The detection of the plcAvirulence gene coding for PI-PLC is generally employed to differentiate hemolytic and nonhemolytic strains. Pathogenic and nonpathogenic Listeriaspecies can be differentiated by their activities of hemolysin or PI-PLC [87, 88].

    L. monocytogenesis a microorganism that can be present in many food products, mainly in dairy products, soft cheeses, cheeses made with unpasteurized milk, celery, cabbage, ice cream, hot dogs, and processed meats [87].

    Infection with L. monocytogenescan be treated with antibiotics such as ampicillin, although penicillin is more effective. Some experts recommend the use of gentamicin in people with impaired immunity, including neonates, and in cases of meningitis and endocarditis. Ampicillin is only used in pregnant women with isolated listerial bacteremia. Other antibiotics that can be used are trimethoprim-sulfamethoxazole and vancomycin. Cephalosporins should not be used to treat listeriosis because they are ineffective against the microorganism [89, 90].

    The general guidelines to prevent listeriosis are similar to those recommended for other foodborne pathogens. For people at high risk, it is recommended not to consume soft cheeses such as Feta, Brie and Camembert, blue cheeses, or Mexican style cheeses (white cheese, fresh cheese, or panela cheese) unless they are made with pasteurized milk; it is also recommended not to consume smoked seafood, pâtéor refrigerated meat spreads, hot dogs, processed meats or cold cuts, unless they have been reheated at high temperatures; these are just some of the food products that people at high risk should avoid [91].

    Multiple factors associated with the procurement, handling, and food preparation contribute to an increase in the likelihood of contamination, and consequently, consumer’s poisoning. Due to the importance of foodborne diseases, the number of cases presented and their severity, it is necessary to know those measures that help preventing or avoiding them; or getting a disease caused by food poisoning related to bacterial toxins [92–94].

    Toxigenic microorganisms arrive to food products by cross-contamination; they come from the environment or they belong to the normal microbiota, in the case of animals. Once the contaminated food is ingested and reaches the intestines, the microorganisms get established, colonize, and, if the strain is toxigenic, produce the toxins responsible for the damage. Likewise, an incubation process must occur prior to the first symptoms. To prevent the occurrence of such diseases, health care measures, especially hand hygiene of food handlers, should be carried out; in that way, all food sectors such as restaurants, manufacturing, and distribution companies, pay special attention to hygiene measures for food handling to prevent food handlers from inoculating the bacteria they carry on the skin on their hands. Along with other measures, they must ensure food safety, and for this, food sectors will establish policies and activities to ensure maximum quality and food safety throughout the food chain (from procurement and production to consumption) [92, 95–98].

    Some of these standards are described and taken care by the Codex Alimentarius, which, together with the World Health Organization and the Food and Agriculture Organization of the United Nations, has the responsibility to develop and standardize the international food standards. Their objective is to ensure the quality of food products and to protect human health, as well as the correct and fair implementation of these standards. The standards of the Codex Alimentariusapply to processed, semiprocessed, or raw food products. In addition to all the factors used in food processing, food quality standards seek to ensure that food products are produced in hygienic conditions, and that they preserve their nutritional quality. The main standards include microbiological processes, regarding the use of food additives, pesticide use and pest control, as well as, the permissible limits of drugs or hormones used in animal production [66, 99–103].

    For proper handling of food products, facilities, materials, instruments, and equipment must be kept accessible for the cleaning and disinfection process, in order to prevent food contamination by toxigenic bacteria. Cleaning procedures will include the effective removal of food residues or other contaminants; these procedures must be continuous, because some microorganisms have the ability to settle on these surfaces and to survive in adverse conditions by forming biofilm, thus, cleaning with soap and water is not enough. The methods can be chemical, with alkaline and acidic detergents; and physical, with heat, turbulent washes, or vacuum washes. Moreover, brushes or sponges can be used to remove dirt; however, the correct method of use must be considered to ensure efficiency, as well as, not using the same cleaning instrument in areas of processed and unprocessed food. Detergents or disinfectant substances should be used under the conditions proposed by the manufacturer regarding the concentration and time of action, which will depend on the type of surface and the product’s presentation (liquid, solid, or semisolid). Such cleaning processes will be subject to regular monitoring and quality control, registering the areas that were cleaned and the person responsible for the cleaning. The cleaning method will be used depending on what is intended to be cleaned; in the case of smooth surfaces, the use of disinfectant and sponges or brushes to remove residues will be enough; this is done in situ, contrary to those dismantled equipment that require to be cleaned piece by piece. All of the above related to the establishment’s cleaning must be submitted in writing to the personnel responsible for this task for the correct and efficient implementation of cleaning methods [98, 104–106].

    Another important aspect in this sector is pest control. A variety of pests lurk at sites where food is produced; special care must be taken because in most cases these pests act as vehicles for toxigenic bacteria and other pathogens, endangering the consumer’s health. The most common pests are rodents, flies, and cockroaches. To prevent the presence of pests, food facilities should avoid air vents and cracks; regarding food products, these should be stored in high places, inside sealed containers or bags to prevent rodents from smelling the food. For pest control, insect monitoring should be carried out on a continuous basis, through catch patches that may contain pheromones to attract insects, electric lamps against flying insects, among others. Of all insects, flies are the most common pest in food establishments, and they are an important source of disease transmission to food and other forms of food poisoning. It is important that food establishments eradicate flies pest to avoid any contamination of food products, in restaurants, kitchens, and other establishments where food is prepared; adhesive traps can be employed. Traps are used when managing rodent pests; however, an exhaustive planning must be done to determine the number of traps to be placed, as well as location; pest prevention include specifics such as covering air vents, avoiding cracks, and storage of food in high places, inside sealed containers or in bags to prevent rodents from smelling the food. At this point, the cleaning of the workplaces is of high importance, mainly the kitchen and the surfaces that are in contact with food, to ensure quality and food safety [87, 107, 108].

    Food safety is a human right and an obligation of all the governments to ensure it; it refers to the preserved quality of food products without organoleptic alterations, the presence of chemical, physical, or biological pathogens, or other undesirable alterations in the products that may affect the consumer’s health. In order to ensure this characteristic, good practices must be put into operation; identification and control of the potential sources of contamination by the establishment, proper storage of food by separating raw food from processed food, and handling of food products depending on their origin (animal or vegetable). Proper waste management and drainage installation need to be taken into account. Regarding the design and equipment distribution, and the areas where the food is prepared, raw food should be separated, and previously processed food should not be exposed in the same surface. Staff restrooms must be distant from food preparation areas to avoid fecal contamination. The use of suitable uniforms and footwear, air quality, ventilation, and temperature control are essential for a working environment that allows a good development of food processing, and reduces, as much as possible, food poisoning by toxigenic bacteria [101, 109].

    The Hazard Analysis and Critical Control Point (HACCP) system can be an efficient and systematic alternative to prevent toxico-infection; its function is to identify specific hazards and develop control measures to solve them, guaranteeing food safety by seven basic principles: identifying hazards and preventive measures, identifying critical control points, establishing limits, monitoring critical control points, using corrective measures, verifying processes, and registering the applied processes [63, 110].

    As a preventive measure to avoid food contamination and foodborne diseases, World Health Organization (WHO) proposes the five keys for food safety [94].

    Keep clean: It refers to washing hands before and during food preparation; after going to the toilet; washing and sanitizing surfaces and equipment for food preparation, and to keep them away from insects and animals.

    Separate raw and cooked food: Prepare in different surfaces raw and cooked food and use different equipment for each type of food.

    Cook thoroughly: Food cooked thoroughly allow the removal of bacteria and other pathogens; toxins produced by bacteria and pathogens can also be destroyed.

    Keep food at safe temperatures: Do not leave cooked food at room temperature for more than 2 h to avoid bacteria proliferation, and try not to store frozen food for long periods of time.

    Use safe water and raw materials: Safe treated water must be used when preparing food; use fresh food products and wash adequately. Pre-processed products such as pasteurized milk, should be used as directed and not be used beyond their expiry dates.

    The field of research about bacterial toxins is very wide; the determination of the toxins structure and function has allowed the development of biotechnological applications such as the development of antimicrobial drugs, anti-cancer therapy, and vaccine creation.

    Almost all projects focus on the research of vaccines containing portions of attenuated toxin, in order to protect the patient against the effects of the disease. A study carried out by Secore et al., in 2017, showed the efficiency of the tretavalent vaccine against C. difficile, which causes nosocomial infections; this vaccine contains TcdA- and TcdB-attenuated toxins and toxin components CDTa and CDTb. This vaccine showed greater effeciency in golden hamsters and in Rhesus monkeys compared to vaccines containing only the TcdA and TcdB antigens. In the case of the botulinum neurotoxin (BoNT), it is known to be of use in the treatment of muscle atrophies, mainly in facial paralysis, muscular hyperactivity, and dystonias. The BoNT has also been used to prevent facial wrinkles. However, it was found to have a preventive effect on headaches, as it is able to lessen it in some diseases such as neuropathic pain, low back pain, myofascial pain, and bladder pain. Studies supporting this statement have been carried out with studies based on human pain, these studies have shown positive and negative results. They are double-blind studies with placebo control. The positive action of the Botulinum toxin (BTX) has been characterized when administered to cells previously exposed to cigarette smoke; this suggests that it is a preventive agent to reduce the risk of necrosis in the respiratory tissue of patients who smoke [111–113].

    Another notable example of toxin research is the use of toxins for medical treatments. For example, in studies by Lai et al.,they found that the C. jejunidistal cytolethal toxin can be incorporated to the lipid rafts on the membrane with the Cj-CdtA/CdtC subunit; the Cj-CdtB subunit goes through the cell membrane, it translocates to the interior of the cell and reaches the nucleus. This is an advantage that can be used to create drugs paired with the attenuated toxin or to a part of it, so that it can be able to reach the nucleus, be separated from the drug, and act as therapy against cancer, without the toxin causing any damage. Several in vivoand in vitrostudies will be needed to establish it as an alternative cancer therapy [114].

    The mechanisms that develop in the pathway that creates the pore have been revealed in the study of pore-forming toxins (PFT) in the cell membrane. Nowadays, the mechanism of formation is almost completely known stage by stage. The challenge in the research is to know the process in detail and, from that, design therapies with antibodies, drugs, or other compounds that can inhibit its effects to know how the cell senses the presence of the pore, if it is at a concentration level of ions or by cytoplasmic signals, allowing it to run repair mechanisms of membrane damage [115].

    An interesting group of toxins are the immunotoxins, which are formed by a portion of antibody and a portion of toxin; the toxin has an intracellular action to kill the target cells. Most immunotoxins are designed to attack cancer cells; therefore, they are alternative to chemotherapy. The regulation of immunological signals and the treatment against viral and parasite infections are also applications of immunotoxins. Nevertheless, studies should focus on the methods for obtaining the toxin-antibody compounds, because molecular cloning to obtain a hybrid immunotoxin has not been efficient. Therefore, the methods for obtaining and purifying must be improved. The recent results are the creation of smaller immunotoxins with less immunogenicity, leaving only the site of action with the membrane, or the immunogenic site allowing its insertion into the target cell. Related studies are based on the creation and purification of monoclonal antibodies against toxins; for example, the use of an optimized anti-Alpha-toxin antibody of S. aureuscausing pneumonia. This study showed a decrease in the number of bacteria in lungs and kidneys of the evaluated mice; mice showed minimal swelling and intact lung tissue. Thus, the mice had a higher percentage of survival, even with the combined treatment of the anti-Alpha-toxin antibody plus vancomycin or linezolid [95, 116].

    Another alternative is the use of chemicals that inhibit the effect of bacterial toxins. A large number of research papers have been looking for substances that may inhibit the effect of bacterial toxins in human tissue; for example, the use of Bi3+ ion to prevent or treat the hemolytic uremic syndrome caused by E. coliproducing shiga toxin; this ion can be applied to animals and humans. Due to the importance of toxins in the food area, with clinical and pathological consequences, these mechanisms of action and the nature of toxins should be thoroughly investigated, in order to design strategies to prevent and manage effectively toxicoinfections [117].

    It should be of particular attention, the use of toxins as an alternative treatment that allows to have tools for treating diseases such as cancer, the use of immunotoxins and pharmacotoxins.

    Governments should raise food safety as a public health priority, by establishing effective food safety systems to ensure that food producers and suppliers, throughout the food chain, act responsibly and provide safe food to consumers.

    Food contamination can occur at any stage of the manufacturing or distribution process, although the responsibility lies primarily with the producers. Nevertheless, a large part of the foodborne diseases are caused by food that has been improperly prepared or handled at home, in food establishments, or in street markets.

    It is a joint responsibility for consumers, traders, and governments to work together to implement regulations, enforce laws that support, increase, and sustain food safety.

    This study was supported by the Grant Secretaría de Investigación y Posgrado del Instituto Politécnico Nacional (SIP 20160609, 20161129, 20172091, 20171254, and 20171099). Andrea Guerrero Mandujano, Luis Uriel Gonzalez Avila, and Ingrid Palma Martinez held a scholarship from CONACyT. The authors are also grateful to Sofia Mulia for her help in preparing the English version of the manuscript of the chapter.

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    Classification of enteric toxins.

    Source: Adapted from Sears et al. [8].

    Toxins produced by pathogens involved in foodborne diseases are as follows:

    Cholera toxin (Ctx) (Vibrio cholerae), Thermolabile toxin (LT) Thermostable toxin (ST) (Enterotoxigenic E. coli), Shiga Toxin (Shigella dysenteriae and E. coli O157:H7) Botulinum toxin (BTX) (Clostridium botulinum), CPE Enterotoxin (Clostridium perfringens), Alpha-Toxin, Beta-Toxin, Epsilon-Toxin and Iota-Toxin (C. perfringens), Toxin A/Toxin B (Clostridium difficile), Enterotoxins (A, B, C1, C2, D and E, G, H, I, J), Toxic Shock Syndrome Toxin (TSST-1), Cereulide, and hemolysin BL (HBL), nonhemolytic enterotoxin (NHE) (S. aureus), Citotoxin K or CytK (Bacillus cereus) [9–15].

    The high population growth and the food marketing, have generated pathogens causing FBDs to be quickly transported, this has produced outbreaks in different regions, affecting the morbidity, mortality, and economy of the population involved. The trend seen in the United States, the United Kingdom, and Europe indicates that the incidence of FBDs is increasing; this will be a health problem in the following years [4, 16].

    There are different types of genus commonly associated with FBDs such as Campylobacter spp., enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), Salmonella spp., Shigella spp., Shiga toxin-producing E. coli (STEC) and V. cholerae [4, 17].

    A total of 66% of foodborne diseases is caused by bacteria. Major diseases include botulism caused by C. botulinum, gastroenteritis caused by E. coli strains, Salmonellosis and Staphylococcal poisoning. Moreover, B. cereus and V. cholerae are bacteria frequently reported as causative agents of toxicoinfection by food [18, 19].

    In some countries, food poisoning caused by S. aureus is the most prevalent; reports indicate that S. aureus can be responsible for up to 41% of food poisoning outbreaks. Although it can affect people of any age, the range with the highest incidence goes from 20 to 49 years of age, where up to 48% of the cases can be concentrated. The main food products related to food poisoning caused by S. aureus are chicken and eggs, cakes, pastas, sauces, milk, and its derived products [20].

    Globally, the highest number of cases is caused by ETEC, 233 million cases, and Shigella spp., 188 million cases; however, the highest numbers of deaths are caused by EPEC, 121,455 deaths; ETEC, 73,041 deaths, and Shigella spp., 64,993 deaths. In total, 40% of the cases and 43% of the deaths caused by FBDs occurred in children under the age of 5 years old [17].

    Food poisoning caused by B. cereus can occur any time of the year; it does not present a defined geographical distribution, and because it is naturally found in the environment, its distribution in various types of food occurs easily, especially in those of plant origin such as cereals and rice. Reports about food poisoning outbreaks caused by B. cereus are underestimated due to the lack of diagnostic tools; however, globally, there are figures where food poisoning caused by this pathogen occupies from 1 to 17.5% of the total cases of food poisoning caused by bacteria [21, 22].

    Food poisoning caused by C. botulinum is less frequent and the epidemiological information about it is scarce; outbreaks of food poisoning caused by this pathogen usually include members of one family, that is, they do not involve a large number of individuals and the main cause of such outbreaks is the consumption of canned food at home [23, 24].

    Food poisoning caused by C. perfringens occurs at any time of the year, but it is more frequent in the last months of the year. It does not present a geographical distribution; in some countries like the United States, the outbreaks caused by this pathogen occupy the second place in foodborne diseases. Generally, this type of outbreaks affect a large number of individuals, therefore, they have a high range of morbidity. In total, 90% of the cases are caused by the intake of meat and poultry products; the contamination of meat and other food products occurs by the contact of pipelines with feces or contaminated surfaces [24, 25].

    Nevertheless, the distribution of pathogens varies depending on the region, due to cultural and economic factors that allow both incidence and mortality to be different for each pathogen associated with FBDs. For example, in Europe, Campylobacter and Salmonella are reported pathogens; their reservoirs are livestock and domestic animals, and food contamination is produced due to bad practices in the food production chain and by cross-contaminations; however, although they play an important role in enteric diseases, they are less frequent than in countries defined by the World Health Organization (WHO) as high-mortality countries (Western Pacific Region and Africa Region), where the sanitary conditions and food and water contamination are factors that increase the incidence and mortality of these genera [17].

    In 2010, WHO wrote a report about the main pathogens involved in FBDs, dividing all countries in regions; these regions were grouped based on adult and infant mortality (Figure 1).

    Geographical distribution of countries by region. Subregions are defined on the basis of infant and adult mortality. Stratum/Layer A = very low infant and adult mortality; stratum B = low infant mortality and very low adult mortality; stratum C = low infant mortality and high adult mortality; stratum D = high infant and adult mortality; and stratum E = high infant mortality and very high adult mortality. AFR: African subregion, AMR: American subregion, EMR: Eastern Mediterranean, EUR: European subregion, SEAR: South-East Asian subregions, WPR: Western Pacific subregion. Adapted from World Health Organization [26].

    The risk group causing FBDs depends on the region, in developing countries such as African regions, South America, and South Asia, pathogens causing diarrheal diseases and the invasive pathogens causing infectious diseases and bacteria are the group that causes FBDs, followed by some cestodes and helminths; nevertheless, African regions, cestodes, and helminths are the group that causes FBDs because health and economic conditions limit proper food handling and preservation [17, 26].

    With the above, as each risk group is different for each region, in the same way, the distribution of the main pathogens involved in FBDs depends on each region, as well as their incidence; however, developing countries continue to show a great number of cases of FBDs. In addition, the prevalence of pathogens in these countries is higher than in developed countries (Figure 2) [4, 26].

    Global burden of FBDs by subregion (DALYS per 100,000 inhabitants) caused by major pathogens. DAYLs: Disability-adjusted life years metric, AFR: African subregion, AMR: American subregion, EMR: Eastern Mediterranean, EUR: European subregion, SEAR: South-East Asian subregions, WPR: Western Pacific subregion. Adapted from World Health Organization [26].

    Additionally, each region has different socioeconomic characteristics, this creates an impact on the incidence and the mortality of FBDs associated with different bacterial pathogens; the Shigella genus occupies the first place in deaths in all regions; however, each region shows a different distribution among the genus that produce the highest number of deaths; this is due to the fact that medical care is different in each region, which means that in some regions a genus causes high mortality and in other regions it is only of medical relevance (Figure 3) [4, 17, 26].

    Median rate per 100,000 of diarrheal illnesses and deaths by region. The scale is on logarithmic basis 10. Adapted from Pires et al. [17].

    In accordance with the above, it is emphasized the importance of medical authorities to know the incidence of the pathogens causing FBDs that circulate in their regions; not only to know the morbidity and mortality rate, but also to provide the population with the appropriate medical care directed to the pathogen causing FBDs.

    The main risk factor involved in bacterial food poisoning is food contamination by pathogenic bacteria that produce toxins; such contamination can occur at any time, that is, from the crop, in the case of vegetables or, just before eating them, due to the consumer’s manipulation; in this way, all the people living on the earth are susceptible to food poisoning. Therefore, food poisoning is a worldwide public health problem, generally the most affected are children, the elderly, pregnant women, and immunocompromised people. As expected, individual factors such as age, gender, place of residence, socioeconomic factors, among others, are crucial in food poisoning acquisition and development [27–29].

    Food contamination can occur from primary production to the final consumer, consequently, there are different contamination risks according to the practices carried out in the different stages such as agricultural, livestock, and fish production; industrialization (in the case of processed food); marketing (points of sale), and transportation to the final consumer (homes, community dining rooms, and restaurants) [30].

    During the primary production, producers should consider the particular characteristics of the environment where they grow or breed and reproduce livestock, by applying measures to prevent any pollution caused by the air, water, or natural fertilizers. In general, the main risk of contamination in primary production is the unsafe agricultural practices such as the use of manure as natural fertilizer and irrigation with sewage, which violates the fundamental principle of preventing, at all costs and contamination of raw materials from fecal matter [31, 32].

    Additionally, another important factor to ensure food safety and good quality is the adequate control of time and temperature when cooking, processing, cooling, and storing food. To achieve a good control of such parameters, it is necessary to consider the physical, chemical, and microbiological characteristics of each type of food, for example, water activity, pH and type, and the initial number of microorganisms presented there. Similarly, other aspects need to be taken into account such as shelf life and usage, that is, whether it is a raw, processed, packaged, or ready-to-eat food [33, 34].

    Microbiological contamination can occur through direct contact or through air, utensils, contact surfaces, or the handler’s hands; therefore, ready-to-eat foods must be separated in space and time from raw or unprocessed foods. In addition, the latter must always be washed or disinfected. In all stages of the food chain, it is indispensable to use water; hence, this could be the main source of food contamination. It is then necessary to control and monitor the type and the source of the water used at each stage; however, when it is used for food handling, water has to be drinkable water that meets the physical, chemical, and microbiological criteria that its name requires [29, 31, 35].

    In terms of facilities, it is important to establish and monitor systems that ensure their maintenance, cleaning, and sanitation. These systems also include an adequate waste management and an effective pest control. The latter constitute a potential risk of any type of contamination; that is why it is necessary to implement measures that prevent the entrance of any type of pests, as well as measures to avoid their nesting and proliferation. Finally, pest eradication must be carried out by any physical, chemical, or biological method that does not represent a threat to health and food safety [27, 31].

    Within the food chain, food transportation plays an important role in preventing contamination and proliferation of microorganisms in food; thus, it is necessary to consider measures to prevent any type of contamination and to provide an environment to control the proliferation of pathogenic microorganisms and the production of bacterial toxins. Some important factors to consider during food transportation are temperature, direct exposure to sunlight, humidity, and airflows. At this stage, the type of containers and the type of packaging also play an important role; the aforementioned and transport conditions should be chosen based on the characteristics of the food that is being transported [36].

    Another important measure is the information that producers and suppliers offer to consumers regarding the characteristics and proper handling of prepackaged foods; this is why, generally, food must be packaged and labeled in such a way that the consumer has enough information to handle, store, and prepare the products appropriately without threatening his or her health. Labels should also include a batch number allowing rapid identification and market recalls of products potentially being dangerous for human consumption [37, 38].

    In general, microorganisms, more specifically bacteria, can proliferate under very different conditions; that is why they can be found in any type of environment. Even though bacteria are good at adapting to the environments they are in, there are certain conditions that promote bacterial growth more than others. These conditions include food, humidity, acidity, temperature, time, and oxygen; all of these are grouped in what is known as FATTOM (Food, Acidity, Time, Temperature, Oxygen, and Moisture). Knowing and avoiding these optimal conditions can help to prevent bacterial growth, bacterial infections, and food poisoning [39–41].

    Most foods contain nutrients required for microbial growth, which makes them easy targets for the microorganisms to develop; therefore, perishable. To reduce the breakdown of food and to prevent foodborne diseases, the proliferation of microorganisms under certain conditions must be controlled, as well as the conditions that must be used to reduce food spoilage to lengthen the time during which physicochemical and organoleptic characteristics must be kept under minimum acceptance parameters. Factors affecting the proliferation rate of microorganisms can be considered as intrinsic and extrinsic [42, 43].

    Intrinsic factors affecting the proliferation rate are more related to the internal characteristics of food products, and the way in which these characteristics maintain or affect the growth of microorganisms; these factors include water activity, pH, oxidation-reduction potential, content and type of nutrients, inhibiting substances, and biological structures [44, 45].

    It is defined as the amount of water available for the growth of microorganisms; microbial proliferation decreases when water availability also decreases. The water available for metabolic activity determines the degree of microbial growth instead of the total moisture content. The unit of measurement for the water that microorganisms require is usually expressed as water activity (Aw), which is defined as the water vapor pressure of food substrate, divided by the water vapor pressure of pure water, at the same temperature. This concept is related to relative humidity (RH), thus: RH = 100 × Aw. The approximate optimal Aw for the growth of most microorganisms is 0.99; most bacteria require an Aw greater than 0.91 to grow. Gram-negative bacteria require higher values than Gram-positive bacteria. Most of the natural food products have an Aw of 0.99 or more. Generally, bacteria have the highest requirements of water activity, fungi have the lowest, and yeasts have intermediate requirements. Most bacteria that decompose food do not grow with an Aw less than 0.91, but fungi and yeasts can grow with values of 0.80 or less, including surfaces partially dehydrated. The lowest value reported for bacteria in food is 0.75 for halophytes, while xerophilic fungi and osmophilic yeasts have shown growth at Aw values of 0.65 and 0.61, respectively [46, 47].

    The pH is defined as the negative logarithm of hydronium ions concentration; it is considered as a unit of measure to establish acidity or alkalinity levels of a substance, in this case food, and it is determined by the number of free hydrogen ions (H+). The effects of adverse pH affect at least two aspects of the microbial cell-functioning of its enzymes and nutrients transportation to the cell.

    The cytoplasmic membrane of microorganisms is relatively impermeable to H+ and OH− ions; its concentration in the cytoplasm remains reasonably constant, despite the wide variations that may occur in the pH of the surrounding medium. When microorganisms are in an environment below or above the neutral level, their ability to proliferate depends on their ability to change the environmental pH to a more appropriate range, since key components like DNA or ATP require a neutral medium [42, 43, 47].

    The pH for the optimal growth of most microorganisms is close to neutrality (pH = 6.6–7.5). Yeasts can grow in an acid environment and thrive in an intermediate range (4.0–4.5), although they survive in values between 1.5 and 8.5. Fungi tolerate a wide range (0.5–11.0), but their growth is generally higher in an acid pH (too acid for bacteria and yeast). Bacterial growth is usually favored by pH values closer to the neutral level. Nevertheless, acidophilic bacteria grow on substrates with a pH of up to 5.2 and below that point the growth reduces dramatically [42, 48].

    In general, fruits, vinegars, and wines have pH values lower than those required for bacterial growth, so they can usually be decomposed by fungi and yeasts. Most vegetables have pH values lower than those from fruits, and consequently, vegetables are more exposed to bacterial or fungi decomposition. In contrast, most meats and sea products have pH values equal or greater than 5.6, making them susceptible to decomposition by bacteria, fungi, and yeasts [44, 48, 49].

    The oxidation-reduction potential (O/R) is an indicator of the oxidizing and reducing power of a substrate; that is, the O/R potential of a substrate can be generally defined as the ease with which a substrate loses or gains electrons (when a food product loses electrons, it oxidizes, whereas, when it gains electrons it is reduced; thus, a food product that easily gives electrons is a good reducing agent and the one that receives electrons is a good oxidizing agent). To achieve optimum growth, some microorganisms require reducing conditions and others require oxidizing conditions. The O/R potential of a system is expressed with the Eh symbol (when electrons are transferred from one compound to another, a potential difference is created between the two compounds; this difference can be measured and expressed as millivolts [mV]). The more oxidized a substance is, the more positive the electrical potential will be; and the more reduced a substance is, the more negative the electrical potential will be. When the concentration of oxidant and reducer is equal, there is an electrical potential of zero [39].

    Saprophytes that are capable of transferring hydrogen as H+ and e− (electrons) to molecular oxygen are aerobic; that is, aerobic microorganisms require positive Eh values (oxidized) for their growth, whereas anaerobic microorganisms require negative values of Eh (reduced). Facultative microorganisms can grow under any of the conditions. It has to be considered that maximum and minimum Eh values (in mV) necessary for aerobic and anaerobic growth could be lethal to the other group. Among food substances that help to maintain reducing conditions are the –SH groups in meats and the ascorbic acid, as well as, reducing sugars in fruits and vegetables. Some aerobic bacteria grow better under slightly reducing conditions being known as microaerophiles such as Lactobacillus and Campylobacter. Most of fungi and yeasts found in food are aerobic, although a few tend to be facultative anaerobes. Regarding the Eh value of food, vegetables, especially juices, tend to have Eh values of +300 to +400 mV; so, it is not surprising to find that aerobic bacteria and fungi are the common cause of decomposition in this type of products. Meats have Eh values around −200 mV; in ground meats, Eh is usually around +200 mV. Various types of cheese show Eh values between −20 and −200 mV [46].

    Microorganisms have nutritional requirements, most of them need external sources of nitrogen, energy, minerals, as well as vitamins, and related growth factors; these requirements are found in our food, so if they have the right conditions to develop, they will. In general, fungi have the lowest nutrient requirement, followed by Gram-negative bacteria, then yeasts and finally, Gram-positive bacteria, which have the highest requirements [46, 50].

    The primary sources of nitrogen used by heterotrophic microorganisms are amino acids. A great number of other nitrogen compounds may serve for this function for several types of organisms. For example, some of them can use free nucleotides and amino acids, while others can be capable of using peptides and proteins. In general, simple compounds like amino acids will be used by almost all of the organisms before attacking more complex compounds such as high molecular weight proteins. The same applies to polysaccharides and lipids [39, 51].

    Microorganisms in food tend to use as energy sources, sugars, alcohols, and amino acids. Fungi are the most efficient in the use of proteins, complex carbohydrates, and lipids because they contain enzymes capable of hydrolyzing these molecules into simpler components; many bacteria have a similar capacity, but most yeasts require simpler molecules. All microorganisms need minerals, although vitamin requirements vary. Fungi and some bacteria can synthesize enough B vitamins to meet their needs, while others need to have a source of vitamins, food products being an excellent source of them [39, 50].

    Gram-positive bacteria are the ones that have lower synthesized capacity, so they need one or more of these components to grow. In contrast, Gram-negative bacteria and fungi are capable of synthesizing the most, if not all, of their requirements and consequently, these two groups of organisms can grow in food products with low content of B vitamins [46, 52, 53].

    Food factors are very important for the development of microorganisms; there are external or extrinsic factors. This term refers to environmental factors that affect the growth rate of microorganisms; these factors include temperature, oxygen availability, and relative humidity, as well as, the presence and activities of other microorganisms [46].

    Microorganisms have an optimal range, as well as a minimum and maximum temperature to grow. Therefore, ambient temperature determines not only the proliferation rate, but also the genera of microorganisms that are going to be developed, along with the microbial activity degree that is registered. The change in only a few degrees in temperature will favor the growth of completely different organisms, and it will result in a different type of food decomposition and/or foodborne disease. Due to these characteristics, thermal treatment is employed as a method to control microbial activity [46, 54].

    The optimal temperature for the proliferation of most microorganisms ranges from 14 to 40°C, although some genera develop below 0°C, and other genera grow at temperatures above 100°C. Nevertheless, food quality must be taken into account when selecting storage temperature. Although it can be desirable to storage all food products at temperatures equal or less to those of refrigeration, this is not the best thing to do to maintain a desirable quality in some food products such as banana, whose quality is best maintained in storage at 13–17°C than at 5–7°C. Similarly, many vegetables are favored at temperatures near 10°C such as potatoes, celery, cabbage, and many others. In each case, the success of storage temperature depends, to a large extent, on the relative humidity and the presence or absence of gases such as carbon dioxide and ozone [46, 55].

    Like temperature, the oxygen availability determines the microorganisms that will be active. Some have an absolute requirement for oxygen, while others grow in total absence of it, and others may grow with or without oxygen. Microorganisms that require free oxygen are called aerobic microorganisms, while those that thrive in the absence of oxygen are called anaerobic; and those that grow both in presence or absence of free oxygen are known as facultative microorganisms [43, 46, 56].

    Carbon dioxide is the most important atmospheric gas that is used to control food microorganisms. Along with oxygen, it is used in packaged food with modified atmosphere. Ozone is another atmospheric gas with antimicrobial properties, and for decades, it has been used as an agent to lengthen shelf life of certain types of food. Although being effective against a variety of microorganisms, it is a highly oxidizing agent;thus, it cannot be used in food products with high lipid content, as it could accelerate rancidity. Normally, ozone levels of 0.15–5.00 ppm in the air inhibit the growth of some bacteria that decompose food as well as yeast growth [46, 57].

    Relative humidity (RH) of the environment is important from the point of view of water activity within food and the growth of microorganisms on surfaces. This extrinsic factor affects microbial growth and can be influenced by temperature. All microorganisms have a high-water requirement, this being needed for their growth and activity [46, 54].

    When the Aw of a food product is set at 0.60, it is important that this food is stored under RH conditions that do not allow food to draw humidity from the air and, therefore, it increases its own Aw from the surface and subsurface to an extent where microbial growth can occur. A high relative humidity can cause humidity condensation in food, equipment, walls, and ceilings. Condensation causes wet surfaces, which lead to microbial growth and decomposition. Microbial growth is inhibited by a low relative humidity. When food products with low Aw values are placed in high RH environments, food takes in moisture until they reach balance. Similarly, food products with high Aw lose moisture when placed in an environment with low RH. There is a relationship between RH and temperature that must be taken into account when selecting the appropriate storage environments for food products. Overall, the higher the temperature, the less the RH, and vice versa [46, 54, 58].

    Bacteria require higher humidity than yeasts and fungi. The optimal relative humidity for bacteria is 92% or higher, while yeasts prefer 90% or higher, and fungi thrive if the relative humidity is between 85 and 90%. Food products suffering superficial decomposition by fungi, yeasts, and specific bacteria, should be stored under low RH conditions. Poorly packed meats such as whole chickens and beef cuts, tend to suffer a lot of superficial decomposition inside the refrigerator before internal decomposition occurs, usually, due to high RH in refrigerators, and to the fact that the biota decomposing meat is essentially aerobic in nature [46, 59].

    Although it is possible to decrease the possibility of superficial decomposition in certain food products by storing them in low RH conditions, it should be remembered that the food itself will lose moisture into the atmosphere under such conditions, and thus, it will become undesirable. When selecting appropriate RH conditions, there should be taken into account both the possibility of superficial microbial growth and the quality that the food product needs to have. By altering the gas atmosphere, it is possible to delay superficial decomposition without lowering the relative humidity [46, 60].

    Some food origin organisms produce substances that can inhibit or be lethal for other organisms; these include antibiotics, bacteriocins, hydrogen peroxide, and organic acids. Bacteriocins produced by lactic acid-producing bacteria originated in various food products such as meat, are of high interest. Bacteriocins produced by Gram-positive bacteria are biologically active proteins with bactericidal action. Some bacteriocins produced by these bacteria inhibit a variety of food pathogens including, B. cereus, C. perfringens, Listeria spp., A. hydrophila, and S. aureus, among others [39, 46].

    Normally food products can reach the final consumer at home, in community dining rooms, or restaurants. Measures to prevent food poisoning should be implemented at these locations, particularly in areas where large volumes of food are distributed such as cold chain, frozen chain, hot chain, and vacuum cooking. Likewise, in the frozen chain, food temperature is gradually lowered to −18°C and defrosted at temperatures higher than 65°C at the time it will be served to the costumer (not before); while in the hot chain, for example, in a buffet, food is kept at temperatures higher than 65°C and it should be consumed within 12 h maximum [61].

    Other important measures are the use of food preservation methods, which can be physical or chemical. Within the physical methods, there are the traditional or industrial pasteurization, dehydration, preservation in modified atmosphere, and irradiation. In order to maintain an adequate quality control and to minimize the risk of food poisoning, microbial markers can be used; these markers do not represent a potential health risk, however, a large number of them indicate deficiencies in hygiene and sanitary quality of food products; it also leads to a decrease in the shelf-life and could be related to the presence of pathogenic microorganisms. The main microbial markers are aerobic mesophilic, total coliforms, fecal coliforms, Enterococci, E. coli, S. aureus, and lactic acid bacteria [62].

    Once the risk factors are identified, it is necessary to establish a system that allows to prevent and decrease all of them; to do this, a method with scientific basis and systematic profile has been established, this is known as Hazard Analysis and Critical Control Point (HACCP). A microbiological approach should consider the type of microorganism or metabolite (toxins) that threatens human health; the analytical methods for its detection and quantification; the number of samples to be taken and the size of the analytical unit; and the microbiological limits considered to be adequate at specific points in the food chain [63].

    In food products, we can find different types of toxins such as, bacterial, fungal (mycotoxins), algae or plant toxins, as well as metals, toxic chemicals (zinc, copper, and pesticides), and physical contaminants that can cause diseases in people who eat them; all of these can cause the well-known “foodborne diseases” [64].

    Foodborne diseases can be classified into two groups: poisoning and infection.

    Poisoning is caused by the intake of chemical or biological toxins; or toxins produced by pathogens, the latter can be found in food, even if the bacterium is not there.

    Infection is caused by the intake of food containing viable pathogens. Furthermore, a toxic infection (toxicoinfection), formerly known as a toxin-mediated infection, is caused by eating food with bacteria that grow and produce a toxin inside the body [18, 64–66].

    To meet the ideal conditions, microorganisms in food grow and produce toxins. By ingesting contaminated food, toxins are absorbed through the intestinal epithelial lining, and it causes local tissue damage. In some cases, toxins can reach organs such as the kidney or the liver, the central nervous system or the peripheral nervous system, where they can cause some damage [18].

    The most common clinical symptoms of foodborne diseases are diarrhea, vomit, abdominal cramps, headaches, nausea, pain, fever, vomit, diarrhea with mucus and blood (dysentery), and rectal tenesmus. Some of the microorganisms causing foodborne diseases, either from poisoning, intoxication or toxicoinfection are described in Tables 2–4. These diseases are generally diagnosed based on the patient’s clinical record or their symptoms [18–20].

    Pathogens that cause infection.

    Modified from Refs: [18–20].

    Pathogens that cause intoxication.

    Source: Modified from Refs: [18–20].

    Pathogens that cause toxico-infection.

    Source: Modified from Refs: [18–20].

    Toxins produced by pathogens involved in foodborne diseases have different characteristics, some of them are shown in Table 5 [9, 11–15, 67].

    Main toxins produced by pathogens involved in foodborne diseases and their biological effect.

    Note: A-5B indicates that the subunits are separately synthesized but associated by noncovalent bonds during secretion and binding to target. 5B indicates that the binding domain of the protein is composed by five identical subunits. A/B denotes a toxin synthesized as a simple polypeptide divided into domains A and B that can be separated by proteolytic cleavage. HBL: hemolysin BL, NHE: nonhemolytic enterotoxin.

    Source: Modified from Refs: [9, 11–15, 67].

    This section will be addressed to some diseases caused by consuming food contaminated with bacterial toxins or microorganisms that produce them. Among some of the most important diseases are the ones transmitted by V. cholerae, S. aureus, B. cereus C. perfringens, C. botulinum and Listeria monocytogenes.

    V. cholerae has a free life cycle, it is ubiquitous in aquatic environments; it is able to remain virulent without multiplying in fresh water and sea water for a long time. They are more frequent in temperate waters and can be isolated in seafood and fish. The most notable species are V. cholerae O1 and O139, causative serogroups of Cholera. Non-O1 strains and the rest of the species cause cholera-like diarrheal syndromes, but they are not as severe, although they frequently produce extraintestinal infections [68–70].

    The CTX toxin (Cholera toxin) is the main virulence factor of V. cholerae O1 (Ogawa, Inaba, and Hikojima serotypes, Classical and El Tor biotypes) and O139; it contributes to cause profuse diarrhea, after an incubation period from 2 h to 5 days; stools have the appearance of rice water, there is dehydration and electrolyte imbalance, which can lead to death. Approximately 75% of the infected people are asymptomatic, that is, they do not develop the symptoms aforementioned; however, the pathogen is shed in their feces for 7–14 days, which is a very serious source of contamination since it is possible to infect others. The most vulnerable groups are children, adults, and people infected with the HIV virus [68, 69, 71].

    This toxin can be identified by the presence of the ctxAB gene. V. cholerae no-O1 has the ctx gene but it is rarely expressed; nevertheless, a faster test is not yet available, although the WHO is currently in the process of validating new rapid diagnoses. The bacteria can be isolated and identified from stool samples by using laboratory procedures [24, 69, 71].

    Efficient treatment resides in prompt rehydration through oral solutions or intravenous fluids. The use of antibiotics is suggested only when there is severe dehydration. The supply of safe drinking water, the adequate sanitation, and food security are essential to prevent the emergence of Cholera. Moreover, vaccines administration has emerged because control measures to prevent contamination are insufficient; this is the reason why oral vaccines have been developed as tools to prevent outbreaks. These vaccines are given to more vulnerable populations in areas where the disease is endemic. Experience in different mass vaccination campaigns in countries such as Mozambique, Indonesia, Sudan, and Zanzibar clearly indicates that vaccination requires careful and early planning and preparation, and therefore, it cannot be improvised at the last minute [71].

    The lack of toxicity combined with stability and the relative ease to express the Cholera Toxin Subunit B (CTB) has contributed to be an easily manageable adjuvant. The ability to express protein in a wide variety of organisms broadens even further its application potential. CTB is currently being used in vaccines such as Dukoral, a vaccine against V. cholerae that consists of dead bacteria and recombinant CTB. It has been approved as adjuvant for vaccines in Europe and in Canada; and given the excellent adjuvant effect, this protein is likely to play an important role in vaccine formulation in the future [72].

    Staphylococcal foodborne illness is one of the most common diseases acquired by S. aureus. It is one of the most concerned diseases by public health programs in the world; it is due to the production of one or more toxins by the bacteria during their growth at permissive temperatures; however, the incubation period of the disease depends on the amount of ingested toxin. Small doses of enterotoxins can cause the disease; for example, a concentration of 0.5 ng/mL in contaminated chocolate milk has been reported to cause large outbreaks [73].

    S. aureus produces various toxins. Staphylococcal enterotoxins are a family of nine thermostable enterotoxin serotypes belonging to a large family of pyrogenic toxins (superantigens). Pyrogenic toxins can cause immunosuppression and nonspecific T cell proliferation. Enterotoxins are highly stable and they resist high temperatures (which makes them suitable for industrial use) and environmental conditions of drying and freezing. They are also resistant to proteolytic enzymes (pepsin and trypsin) at low pH, enabling them to be fully functional in the digestive tract after infection [73].

    The mechanism by which poisoning is caused is not entirely clear yet. However, enterotoxins have been observed to directly affect the intestinal epithelium and the vagus nerve causing stimulation of the emetic center. It is estimated that 0.1 μg of enterotoxin can cause staphylococcal poisoning in humans. Apart from causing poisoning, S. aureus can also cause toxic shock syndrome due to the production of the Toxic Shock Syndrome Toxin 1 (TSST-1) and Enterotoxin Type B [65, 73, 74].

    Symptoms include nausea, vomit, abdominal cramps, salivation, diarrhea could be present or absent. The first three symptoms are the most common ones. Usually, it is a self-limiting disease and can be cured in 24–48 h, but it can become severe, especially in children, the elderly, and immunocompromised people. Toxic shock syndrome is characterized by high fever, hypotension, erythematous rash (similar to scarlet fever, peeling of the skin during recovery, flu-like symptoms, vomiting, and diarrhea) [73–75].

    The diagnosis of the disease is carried out by detecting the staphylococcal enterotoxin in the food or by recovering at least 105S. aureus/g from food leftovers. The enterotoxin can be detected by several methods: bioassays, molecular biology, and immunological techniques. The isolated strains can be genetically characterized by multilocus sequences from the spa or SCCmec gene, and pulsed-field electrophoresis [73].

    The mainly involved food products in outbreaks and where S. aureus can grow optimally, since they are stored at room temperature, are meat and its derived products, poultry and eggs, milk and its derived products, salads, and bakery products (cream-filled cakes and stuffed sandwiches) [65, 73].

    Other factors that must be taken into account are the emergence of methicillin resistant strains, which may be found in food (mainly in meat and milk). It is important to note that many of the isolates obtained from outbreaks are not tested for antimicrobial susceptibility; due to the various problems that these strains can create, the antimicrobial susceptibility test should be performed. They have been reported to be causative agents of outbreaks in blood infections and wounds in immunocompromised patients in hospitals [65, 73].

    Foodborne illness due to S. aureus may be preventable. It is known that the permissible temperature for the growth and production of the enzyme is between 6 and 46°C; thus, food products could be cooked above 60°C and refrigerated below 5°C. Therefore, maintaining the cold chain of food can prevent the growth of the microorganism. By using good manufacturing practices and good hygiene practices, the contamination by S. aureus can be prevented [73].

    B. cereus is a ubiquitous microorganism in the environment, and it can easily contaminate any food production and processing system, due to the formation of endospores. The bacterium can survive pasteurization and cooking processes [11, 15].

    It has been demonstrated that this microorganism produces, cereulide or emetic toxin; three enterotoxins, hemolysin BL (HBL), nonhemolytic (NHE), cytotoxin K (CytK), which are responsible for the emetic syndrome and diarrhea; and three phospholipases, phosphatidylinositol hydrolase, phosphatidylcholine hydrolase, and hemolytic sphingomyelinase. Cereulide is a thermostable cyclic peptide that causes emesis by stimulating the afferent vagal pathway through its bond to the serotonin receptor. The toxin is produced during the stationary phase of growth of the microorganism and it accumulates in food over time. The structure of the toxin explains its resistance to food processing methods. In contrast, inside the small intestine of the host, the thermolabile enterotoxins, HBL and NHE, produced during the exponential phase of the vegetative growth of the bacterium are the cause of diarrheal syndrome; the proteins that form enterotoxins (binding and lithic factors) are unable to traverse intact the gastric barrier; that is why it is considered that preformed or extracellular enterotoxins in food are not involved in the pathogenesis of the bacterium. It is believed that the spore germination that reaches the small intestine, the growth, and the simultaneous production of the enterotoxin are the ones that cause diarrhea. HBL is a hemolysin formed by three components, two protein subunits (L2 and L1), and one B protein; it has hemolytic, cytotoxic, and dermonecrotic effect, and it induces vascular permeability. NHE also consists of three components: NheA, NheB, and NheC. It has been demonstrated that strains producing emetic toxin do not produce enterotoxin. The cytotoxin K is similar to the Alpha-toxin of S. aureus and the Beta-toxin of C. perfringens [13, 15, 76].

    Furthermore, the enterotoxin FM (EntFM) has been described; it is a 45 kDa polypeptide encoded by the entFM gene, located in the bacterial chromosome. It has not been directly involved in food poisoning; however, the presence of the gene in strains that cause diarrheal outbreaks has been detected; in experiments with mice and rabbits, it causes vascular permeability [11].

    The emetic syndrome is characterized by nausea and vomit similar to those produced by S. aureus poisoning. Symptoms appear soon after consuming food contaminated with the preformed toxin. Generally, poisoning develops with mild symptoms, usually lasting no more than 1 day, but severe cases require hospitalization. The diarrhea that is caused belongs to the secretory type, similar to the one produced by V. cholerae. Colic pain occurs similar to that of C. perfringens poisoning. Both syndromes are self-limiting [13, 15, 77].

    Enterotoxins can be detected by immunoassays or molecular biology (conventional PCR and multiple PCR) by looking for the ces gene (nonribosomal production of cereulide); by detecting the hblD, hblC, and hblA genes encoding the L1, L2, and B protein components of the HBL toxin, respectively; or the nheA, nheB, and nheC genes of the NHE toxin components. The 16S ribosomal gene can be looked for by real-time PCR [11, 13, 77].

    Apart from causing food poisoning, B. cereus can also cause local and systemic infections in immunocompromised patients, neonates, people taking drugs, and patients with surgical or traumatic wounds, or catheters [15].

    The most susceptible food products to be contaminated include flours, meats, milk, cheese, vegetables, fish, rice and its derived products; generally, in food with high content of starch. The strains produced by the emetic toxin grow well in rice dishes (fried and cooked) and other starchy products; although, there have been studies where it has been demonstrated that the toxin can be in different types of food products; while strains producing diarrheagenic toxins grow in a wide variety of food products, from vegetables to sauces and stews [15, 77].

    Strains isolated from infections have been shown to be sensitive to chloramphenicol, clindamycin, vancomycin, gentamicin, streptomycin, and erythromycin; they are resistant to β-lactam antibiotics, including third-generation cephalosporins [15].

    Inadequate cooking temperatures, contaminated equipment, and poor hygiene conditions at the food processing and preparation sites are the major factors that contribute to food poisoning by B. cereus and its toxins; that is why, it is suggested to store food at temperatures lower than 4°C or to cook them at temperatures higher than 100°C, and to reheat or cool food rapidly, to avoid prolonged exposure to temperatures that allow spore germination and to diminish the risks of a possible poisoning [11].

    C. perfringens is an anaerobic bacterium that creates spores that survive in soil, sediments, and areas subject to both human and animal fecal contamination. It is widely distributed in the environment and is frequently found in the human intestine and in several domestic and wild animals’ intestines [78].

    C. perfringens is classified into five groups (A, B, C, D, and E), due to the different toxins it produces (alpha, beta, epsilon, and iota). The Alpha-toxin is produced by all the five groups. The Beta-toxin forms selective pores for monovalent ions in the lipid bilayers, functioning as a neurotoxin capable of producing arterial constriction. The Epsilon-toxin is the most potent clostridial toxin after tetanus and botulinum neurotoxins (BoNTs). It is produced and secreted by a prototoxin that acquires its maximum biological activity by undergoing a specific proteolytic cleavage; its activation can be catalyzed by trypsin, chymotrypsin, and a zinc metalloprotease [12].

    The toxin receptor is unknown, but it is known to be a surface protein anchored by glycosylphosphatidylinositol. Its main biological activity is the edema generation; it is lethal but not hemolytic. The Iota-toxin is a member of the binary toxin family, since it is formed by a binding peptide (Ib) necessary for the internalization of the enzymatic peptide (Ia; ADP-ribosyltransferase). Proteolytic removal of a propeptide fragment is required to allow Ib to be inserted into the membrane and to interact with Ia. Ib, when inserted into the membrane, forms a heptameric pore that allows the exit of K+ and Na+ ions, and the entry of Ia, which once inside the cell, is ribosylated by the G-actin; it depolymerizes the filaments of Actin by destroying the cellular cytoskeleton. The Iota-toxin is dermonecrotic, cytotoxic, enterotoxic, and induces intestinal histopathological damage [12].

    However, the virulence of this bacterium is not only due to the presence of these 4 toxins; there have also been described 15 toxins within which the CPE enterotoxin is responsible for causing diarrhea in humans and animals, and it is produced by Type A strains. This toxin is associated with 5 or 15% of gastrointestinal diseases in humans different from food poisoning such as diarrhea produced by antibiotics; the NetB toxin is frequently related to necrotic enteritis in birds and the Beta2-toxin is apparently associated with enteritis. The production of toxins in the digestive tract is associated with sporulation. The disease is foodborne; and only one case has implied the possibility of poisoning caused by the preformed toxin [12, 78, 79].

    C. perfringens causes food poisoning characterized by severe abdominal cramps and diarrhea beginning after 8–22 h of food intake, the disease ends 24 h after the intake; although, in some cases the disease may persist for 1–2 weeks. Additionally, there is a more severe but less frequent disease caused by eating a food product contaminated with type C strains; this disease is known as necrotic enteritis or pig-bel disease, and it is often fatal. Deaths caused by necrotic enteritis are due to intestinal infection and necrosis, as well as by septicemia, the elderly people being the most affected population [78].

    The disease diagnosis is confirmed by the presence of the toxin in the stools of patients; either by traditional methods (culture from the stools or the food involved) or by molecular methods by looking for the following genes: cpe (CPE toxin), plc (Alpha-toxin), and etx (Epsilon-toxin) [12, 78, 79].

    Among the main food products involved are meat and its derived products. The disease can be prevented if the food has been properly cooked; although, there may be a risk of cross-contamination if the cooked food comes in contact with raw and contaminated ingredients, as well as contaminated surfaces [78].

    There is no specific treatment or established cure for the infections caused by the toxins of the bacteria. Supportive care includes administration of intravenous fluids, oral rehydration salts solutions, and medication for fever and pain control. The treatment of gas gangrene is based on surgical measures with debridement and removal of the affected tissue and administration of high doses of antibiotics. Necrotizing enterocolitis is treated systemically with penicillin G, metronidazole or chloramphenicol; 50% of the cases require surgical treatment in which a segmental jejunum resection is performed. The antibiotics active against anaerobic bacteria are effective; however, there are strains resistant to penicillin and clindamycin, therefore, it is suggested to perform antimicrobial susceptibility tests, especially in patients with severe disease and those requiring long-term treatments [9, 80].

    C. botulinum is a spore-forming microorganism; these spores can remain viable for long periods of time when the environmental conditions are absolutely unfavorable for the development of the microorganism [60].

    Four groups are recognized in C. botulinum, as well as seven antigenic variants of botulinum neurotoxins (A–G). Groups I and II are primarily responsible for botulism in humans; Group III is responsible for causing botulism in several animal species, and Group IV appears not to be associated with the disease in either humans or animals. Group I is also known as C. botulinum-proteolytic (mesophilic microorganisms), while group II is known as C. botulinum-non-proteolytic (psychrophilic microorganisms). Group I forms spores that are highly resistant to heat, the “Botulinum cook” (121°C/3 min) given to canned foods with a low content of acid is designed to inactivate them; neurotoxins formed in this group are A, B, F, and H. Group II forms moderately heat-resistant spores, and the neurotoxins formed are B, E, and F. Botulism types A, B, E, and F rarely cause the disease in humans, whereas in animals it is caused by types C and D. Toxins are resistant to proteolytic reactions and to denaturation into the gastric apparatus. Botulinum toxins are metalloproteins with endopeptidase activity that require zinc; the general structure shows two chains with a molecular weight of 150 kDa, the double chain is subdivided into a heavy (H) structure constituted by a nitrogen terminal domain (HN), and a carboxyl-terminal (HC), and a lighter structure (L) that performs the catalytic function of the toxin. HC is responsible for binding to presynaptic receptors for internalization, and HN is called translocation domain [81–83].

    C. botulinum, is a bacterial species known simply for producing the botulinum toxin. The number of genes in Group II strains coding for the neurotoxin is variable; there may be one to three genes that encode one to three different neurotoxins; if there are two genes, there can be one active toxin and an inactive toxin, or both toxins can be active. In Group II, the presence of only one gene has been described, that is why there is only one neurotoxin; however, in other studies it has been demonstrated that in Type F strains the toxin has part of Type B and Type E neurotoxins. Botulinum neurotoxins form complexes with accessory proteins (hemagglutinin and nonhemagglutinin), which protect the neurotoxin and facilitate their adsorption into the host. The hemagglutinin complex of the neurotoxin type A specifically binds the cell adhesion protein, E-cadherin, by binding the epithelial cell and facilitating the adsorption of the neurotoxin complex from the intestinal lumen. Dual toxin-producing strains have been isolated from botulism in humans, the environment, and food; recently there have been found strains that produce three botulinum toxins called F4, F5, and A2. The significance of producing two or more toxins on virulence, as well as the evolutionary consequences are not yet clear. Phylogenetic studies show evidence of horizontal gene transfer; the production of the dual toxin in Group I and the production of a single toxin in Group II is still not clear. Therefore, studies with toxins isolated and purified from the different groups of C. botulinum are still being carried out [81–83].

    Botulism is a severe disease with a high fatality rate. The typical symptoms are flaccid muscle paralysis, sometimes it starts with blurred vision followed by an acute symmetrical decrease of bilateral paralysis that, if untreated, can lead to paralysis of the respiratory and cardiac muscles. If severe cases are not fatal, the patient may improve his/her condition after months or even years. There are three types of botulism: infant/adult intestinal botulism, wound botulism, and foodborne botulism. The first type (infant/adult intestinal botulism) is an infection associated with the multiplication of the microorganism and neurotoxin formation in the intestine; the second type (wound botulism) is an infection associated with cell multiplication and toxin formation in the wound, often acquired after drug abuse; and the third type (foodborne botulism) is a poisoning caused by the consumption of neurotoxin preformed in food. An amount of 30 ng of toxin is enough to cause the disease and sometimes death. Symptoms appear between 2 h and 8 days after the intake of contaminated food, although they may occasionally appear between 12 and 72 h [81, 82].

    Botulism can be diagnosed only by clinical symptoms, but its differentiation from other diseases can be difficult. The most effective and direct way of confirming the disease in the laboratory is by demonstrating the presence of the toxin in the serum, in stools of patients, or in food products consumed by them. One of the most sensitive and widely used methods to detect the toxin is through neutralization in a rodent. This test takes 48 h, and culture of specimens takes from 5 to 7 days. Infant botulism is diagnosed by detecting botulinum toxins and the microorganism in the stools of children [78].

    Approximately 90% of the reported cases are related to the consumption of home-made preserved food, especially vegetables; the industrial preparation of meat and fish is rarely associated with botulism. Food products where spores of the bacteria or the botulinum toxin can be found are canned corn, pepper, soups, beets, asparagus, ripe olives, spinach, tuna chicken, chicken liver, ham, sausages, stuffed eggplants, lobster, and honey, just to name a few [78, 82].

    To prevent the chances of getting botulism through food, it is necessary to carry out appropriate control measures in food processing and handling, especially when new technologies are introduced or modified. Applying the “Botulinum cook” in the modern industry allows to secure canned foods. The use of chlorine and chlorinated compounds can help sanitize places that handle food industrially. Spores can also be inactivated with ozone and ethylene oxide [81, 82].

    L. monocytogenes is a facultative intracellular microorganism widely distributed in nature, capable of surviving both in the soil and the cytosol of a eukaryotic cell. Considering somatic (O) and flagellar (H) antigens, this bacterium can be classified into 13 serotypes (1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, 4b, 4c, 4d, 4e, 7), but only the serotypes 1/2a, 1/2b, and 4b are responsible for more than 98% of the cases of human listeriosis. Furthermore, it has also been grouped into four lineages (I, II, III, and IV), where lineage I (serotypes: 1/2b, 3b, and 4b) and lineage II (serotypes: 1/2a, 1/2c, 3a, and 3c) include most strains isolated from clinical cases; lineage I strains have a greater pathogenic potential. Lineages III and IV include strains of serotypes 4a, 4c, and an atypical 4b [84].

    L. monocytogenes expresses multiple virulence factors, which allow to enter and survive in several nonphagocytic cells. After cellular internalization, listeriolysin O (LLO) and two phospholipases mediate the escape of the bacterium from the endocytic vesicle into the cytoplasm, where the microorganism divides and submits the F-actin based on mobility to spread from cell to cell. The LLO (coded by the gene hly) is a cholesterol-dependent toxin; it is able to form pores in the membrane of phagosomes, allowing L. monocytogenes to escape from primary and secondary vacuoles. The cytolytic activity of LLO increases with the action of a phosphatidylinositol phospholipase C (PI-PLC), the substrate of which is phosphatidylinositol; and a phosphatidylcholine phospholipase C (PC-PLC), which is a lecithinase with enzymatic activity over phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine. PC-PLC is expressed as a protoenzyme and zinc-dependent metalloprotease Mpl is required for its maturation; so once free in the cytosol, the bacterium acquires the necessary nutrients for intracellular multiplication. Some studies have shown that LLO is a critical invasion factor, which perforates the plasma membrane of the host cell to activate the internalization of the bacterium in human hepatocytes. Moreover, other studies have shown that LLO fails to mediate the intracellular survival of L. monocytogenes in neutrophils, where early degranulation leads to the release of proteases such as matrix metalloproteinase (MMP)-8, degrading LLO and avoiding the perforation of the membranes [84–86].

    L. monocytogenes causes a severe infection known as listeriosis, which is usually acquired after the intake of food contaminated with the microorganism. The disease mainly affects pregnant women, newborns, the elderly, and immunocompromised people, so it is rare for the disease to occur outside the aforementioned groups. Listeriosis is a mild disease in pregnant women, but it is severe in fetus and newborns. People over 65 years of age or immunosuppressed people can develop infection in the bloodstream (sepsis) or in the brain (meningitis or encephalitis). Sometimes the infection can affect bones, joints, thorax, and abdomen. Listeriosis can cause fever and diarrhea similar to that caused by other foodborne microorganisms and is rarely diagnosed. Pregnant women with listeriosis have fever, fatigue, and muscle pain (flu-like symptoms). During pregnancy, the organism can cause miscarriage, stillbirth, premature labor, and infection in the newborn. In the other risk groups, the symptoms are headaches, neck stiffness, confusion, loss of balance, seizures, fever and muscle pain. People with invasive listeriosis usually develop symptoms from 1 to 4 weeks after ingesting food contaminated with the bacterium; although symptoms have been reported after 70 days of exposure or on the same day of the poisoning. The disease is usually diagnosed by culturing the bacterium from tissues or fluids such as blood, cerebrospinal fluid, or placenta. From food products, this microorganism can be detected by various methods such as the use of chromogenic media; immunological methods, although some are nonspecific; molecular methods (hybridization, PCR, and real-time PCR); microarrays or biosensors; and also specific commercial methods. The detection of the plcA virulence gene coding for PI-PLC is generally employed to differentiate hemolytic and nonhemolytic strains. Pathogenic and nonpathogenic Listeria species can be differentiated by their activities of hemolysin or PI-PLC [87, 88].

    L. monocytogenes is a microorganism that can be present in many food products, mainly in dairy products, soft cheeses, cheeses made with unpasteurized milk, celery, cabbage, ice cream, hot dogs, and processed meats [87].

    Infection with L. monocytogenes can be treated with antibiotics such as ampicillin, although penicillin is more effective. Some experts recommend the use of gentamicin in people with impaired immunity, including neonates, and in cases of meningitis and endocarditis. Ampicillin is only used in pregnant women with isolated listerial bacteremia. Other antibiotics that can be used are trimethoprim-sulfamethoxazole and vancomycin. Cephalosporins should not be used to treat listeriosis because they are ineffective against the microorganism [89, 90].

    The general guidelines to prevent listeriosis are similar to those recommended for other foodborne pathogens. For people at high risk, it is recommended not to consume soft cheeses such as Feta, Brie and Camembert, blue cheeses, or Mexican style cheeses (white cheese, fresh cheese, or panela cheese) unless they are made with pasteurized milk; it is also recommended not to consume smoked seafood, pâté or refrigerated meat spreads, hot dogs, processed meats or cold cuts, unless they have been reheated at high temperatures; these are just some of the food products that people at high risk should avoid [91].

    Multiple factors associated with the procurement, handling, and food preparation contribute to an increase in the likelihood of contamination, and consequently, consumer’s poisoning. Due to the importance of foodborne diseases, the number of cases presented and their severity, it is necessary to know those measures that help preventing or avoiding them; or getting a disease caused by food poisoning related to bacterial toxins [92–94].

    Toxigenic microorganisms arrive to food products by cross-contamination; they come from the environment or they belong to the normal microbiota, in the case of animals. Once the contaminated food is ingested and reaches the intestines, the microorganisms get established, colonize, and, if the strain is toxigenic, produce the toxins responsible for the damage. Likewise, an incubation process must occur prior to the first symptoms. To prevent the occurrence of such diseases, health care measures, especially hand hygiene of food handlers, should be carried out; in that way, all food sectors such as restaurants, manufacturing, and distribution companies, pay special attention to hygiene measures for food handling to prevent food handlers from inoculating the bacteria they carry on the skin on their hands. Along with other measures, they must ensure food safety, and for this, food sectors will establish policies and activities to ensure maximum quality and food safety throughout the food chain (from procurement and production to consumption) [92, 95–98].

    Some of these standards are described and taken care by the Codex Alimentarius, which, together with the World Health Organization and the Food and Agriculture Organization of the United Nations, has the responsibility to develop and standardize the international food standards. Their objective is to ensure the quality of food products and to protect human health, as well as the correct and fair implementation of these standards. The standards of the Codex Alimentarius apply to processed, semiprocessed, or raw food products. In addition to all the factors used in food processing, food quality standards seek to ensure that food products are produced in hygienic conditions, and that they preserve their nutritional quality. The main standards include microbiological processes, regarding the use of food additives, pesticide use and pest control, as well as, the permissible limits of drugs or hormones used in animal production [66, 99–103].

    For proper handling of food products, facilities, materials, instruments, and equipment must be kept accessible for the cleaning and disinfection process, in order to prevent food contamination by toxigenic bacteria. Cleaning procedures will include the effective removal of food residues or other contaminants; these procedures must be continuous, because some microorganisms have the ability to settle on these surfaces and to survive in adverse conditions by forming biofilm, thus, cleaning with soap and water is not enough. The methods can be chemical, with alkaline and acidic detergents; and physical, with heat, turbulent washes, or vacuum washes. Moreover, brushes or sponges can be used to remove dirt; however, the correct method of use must be considered to ensure efficiency, as well as, not using the same cleaning instrument in areas of processed and unprocessed food. Detergents or disinfectant substances should be used under the conditions proposed by the manufacturer regarding the concentration and time of action, which will depend on the type of surface and the product’s presentation (liquid, solid, or semisolid). Such cleaning processes will be subject to regular monitoring and quality control, registering the areas that were cleaned and the person responsible for the cleaning. The cleaning method will be used depending on what is intended to be cleaned; in the case of smooth surfaces, the use of disinfectant and sponges or brushes to remove residues will be enough; this is done in situ, contrary to those dismantled equipment that require to be cleaned piece by piece. All of the above related to the establishment’s cleaning must be submitted in writing to the personnel responsible for this task for the correct and efficient implementation of cleaning methods [98, 104–106].

    Another important aspect in this sector is pest control. A variety of pests lurk at sites where food is produced; special care must be taken because in most cases these pests act as vehicles for toxigenic bacteria and other pathogens, endangering the consumer’s health. The most common pests are rodents, flies, and cockroaches. To prevent the presence of pests, food facilities should avoid air vents and cracks; regarding food products, these should be stored in high places, inside sealed containers or bags to prevent rodents from smelling the food. For pest control, insect monitoring should be carried out on a continuous basis, through catch patches that may contain pheromones to attract insects, electric lamps against flying insects, among others. Of all insects, flies are the most common pest in food establishments, and they are an important source of disease transmission to food and other forms of food poisoning. It is important that food establishments eradicate flies pest to avoid any contamination of food products, in restaurants, kitchens, and other establishments where food is prepared; adhesive traps can be employed. Traps are used when managing rodent pests; however, an exhaustive planning must be done to determine the number of traps to be placed, as well as location; pest prevention include specifics such as covering air vents, avoiding cracks, and storage of food in high places, inside sealed containers or in bags to prevent rodents from smelling the food. At this point, the cleaning of the workplaces is of high importance, mainly the kitchen and the surfaces that are in contact with food, to ensure quality and food safety [87, 107, 108].

    Food safety is a human right and an obligation of all the governments to ensure it; it refers to the preserved quality of food products without organoleptic alterations, the presence of chemical, physical, or biological pathogens, or other undesirable alterations in the products that may affect the consumer’s health. In order to ensure this characteristic, good practices must be put into operation; identification and control of the potential sources of contamination by the establishment, proper storage of food by separating raw food from processed food, and handling of food products depending on their origin (animal or vegetable). Proper waste management and drainage installation need to be taken into account. Regarding the design and equipment distribution, and the areas where the food is prepared, raw food should be separated, and previously processed food should not be exposed in the same surface. Staff restrooms must be distant from food preparation areas to avoid fecal contamination. The use of suitable uniforms and footwear, air quality, ventilation, and temperature control are essential for a working environment that allows a good development of food processing, and reduces, as much as possible, food poisoning by toxigenic bacteria [101, 109].

    The Hazard Analysis and Critical Control Point (HACCP) system can be an efficient and systematic alternative to prevent toxico-infection; its function is to identify specific hazards and develop control measures to solve them, guaranteeing food safety by seven basic principles: identifying hazards and preventive measures, identifying critical control points, establishing limits, monitoring critical control points, using corrective measures, verifying processes, and registering the applied processes [63, 110].

    As a preventive measure to avoid food contamination and foodborne diseases, World Health Organization (WHO) proposes the five keys for food safety [94].

    Keep clean: It refers to washing hands before and during food preparation; after going to the toilet; washing and sanitizing surfaces and equipment for food preparation, and to keep them away from insects and animals.

    Separate raw and cooked food: Prepare in different surfaces raw and cooked food and use different equipment for each type of food.

    Cook thoroughly: Food cooked thoroughly allow the removal of bacteria and other pathogens; toxins produced by bacteria and pathogens can also be destroyed.

    Keep food at safe temperatures: Do not leave cooked food at room temperature for more than 2 h to avoid bacteria proliferation, and try not to store frozen food for long periods of time.

    Use safe water and raw materials: Safe treated water must be used when preparing food; use fresh food products and wash adequately. Pre-processed products such as pasteurized milk, should be used as directed and not be used beyond their expiry dates.

    The field of research about bacterial toxins is very wide; the determination of the toxins structure and function has allowed the development of biotechnological applications such as the development of antimicrobial drugs, anti-cancer therapy, and vaccine creation.

    Almost all projects focus on the research of vaccines containing portions of attenuated toxin, in order to protect the patient against the effects of the disease. A study carried out by Secore et al., in 2017, showed the efficiency of the tretavalent vaccine against C. difficile, which causes nosocomial infections; this vaccine contains TcdA- and TcdB-attenuated toxins and toxin components CDTa and CDTb. This vaccine showed greater effeciency in golden hamsters and in Rhesus monkeys compared to vaccines containing only the TcdA and TcdB antigens. In the case of the botulinum neurotoxin (BoNT), it is known to be of use in the treatment of muscle atrophies, mainly in facial paralysis, muscular hyperactivity, and dystonias. The BoNT has also been used to prevent facial wrinkles. However, it was found to have a preventive effect on headaches, as it is able to lessen it in some diseases such as neuropathic pain, low back pain, myofascial pain, and bladder pain. Studies supporting this statement have been carried out with studies based on human pain, these studies have shown positive and negative results. They are double-blind studies with placebo control. The positive action of the Botulinum toxin (BTX) has been characterized when administered to cells previously exposed to cigarette smoke; this suggests that it is a preventive agent to reduce the risk of necrosis in the respiratory tissue of patients who smoke [111–113].

    Another notable example of toxin research is the use of toxins for medical treatments. For example, in studies by Lai et al., they found that the C. jejuni distal cytolethal toxin can be incorporated to the lipid rafts on the membrane with the Cj-CdtA/CdtC subunit; the Cj-CdtB subunit goes through the cell membrane, it translocates to the interior of the cell and reaches the nucleus. This is an advantage that can be used to create drugs paired with the attenuated toxin or to a part of it, so that it can be able to reach the nucleus, be separated from the drug, and act as therapy against cancer, without the toxin causing any damage. Several in vivo and in vitro studies will be needed to establish it as an alternative cancer therapy [114].

    The mechanisms that develop in the pathway that creates the pore have been revealed in the study of pore-forming toxins (PFT) in the cell membrane. Nowadays, the mechanism of formation is almost completely known stage by stage. The challenge in the research is to know the process in detail and, from that, design therapies with antibodies, drugs, or other compounds that can inhibit its effects to know how the cell senses the presence of the pore, if it is at a concentration level of ions or by cytoplasmic signals, allowing it to run repair mechanisms of membrane damage [115].

    An interesting group of toxins are the immunotoxins, which are formed by a portion of antibody and a portion of toxin; the toxin has an intracellular action to kill the target cells. Most immunotoxins are designed to attack cancer cells; therefore, they are alternative to chemotherapy. The regulation of immunological signals and the treatment against viral and parasite infections are also applications of immunotoxins. Nevertheless, studies should focus on the methods for obtaining the toxin-antibody compounds, because molecular cloning to obtain a hybrid immunotoxin has not been efficient. Therefore, the methods for obtaining and purifying must be improved. The recent results are the creation of smaller immunotoxins with less immunogenicity, leaving only the site of action with the membrane, or the immunogenic site allowing its insertion into the target cell. Related studies are based on the creation and purification of monoclonal antibodies against toxins; for example, the use of an optimized anti-Alpha-toxin antibody of S. aureus causing pneumonia. This study showed a decrease in the number of bacteria in lungs and kidneys of the evaluated mice; mice showed minimal swelling and intact lung tissue. Thus, the mice had a higher percentage of survival, even with the combined treatment of the anti-Alpha-toxin antibody plus vancomycin or linezolid [95, 116].

    Another alternative is the use of chemicals that inhibit the effect of bacterial toxins. A large number of research papers have been looking for substances that may inhibit the effect of bacterial toxins in human tissue; for example, the use of Bi3+ ion to prevent or treat the hemolytic uremic syndrome caused by E. coli producing shiga toxin; this ion can be applied to animals and humans. Due to the importance of toxins in the food area, with clinical and pathological consequences, these mechanisms of action and the nature of toxins should be thoroughly investigated, in order to design strategies to prevent and manage effectively toxicoinfections [117].

    It should be of particular attention, the use of toxins as an alternative treatment that allows to have tools for treating diseases such as cancer, the use of immunotoxins and pharmacotoxins.

    Governments should raise food safety as a public health priority, by establishing effective food safety systems to ensure that food producers and suppliers, throughout the food chain, act responsibly and provide safe food to consumers.

    Food contamination can occur at any stage of the manufacturing or distribution process, although the responsibility lies primarily with the producers. Nevertheless, a large part of the foodborne diseases are caused by food that has been improperly prepared or handled at home, in food establishments, or in street markets.

    It is a joint responsibility for consumers, traders, and governments to work together to implement regulations, enforce laws that support, increase, and sustain food safety.

    This study was supported by the Grant Secretaría de Investigación y Posgrado del Instituto Politécnico Nacional (SIP 20160609, 20161129, 20172091, 20171254, and 20171099). Andrea Guerrero Mandujano, Luis Uriel Gonzalez Avila, and Ingrid Palma Martinez held a scholarship from CONACyT. The authors are also grateful to Sofia Mulia for her help in preparing the English version of the manuscript of the chapter.

    Forests represent perhaps the most complex terrestrial ecosystem, given their ecosystem role, as well as habitat and socioeconomic development. The increasing pressure exerted by the global economy and climate change leads to the degradation and shrinking of global forest areas [1, 2, 3, 4]. The reduction of the forest area and its degradation have negative repercussions on the environment, in general, but especially on the quality of the air, the soil, and the security of the water resources [5, 6, 7, 8, 9, 10, 11, 12]. Thus, a series of programs and researches were initiated aimed at evaluating, monitoring, and reporting the physical and biological states of the forest (Convention on Long-Range Transboundary Air Pollution (CLRTAP) [13]; UN Collaborative Programme on Reducing Emissions from Deforestation and Forest Degradation (REDD) [14]; International Long Term Ecological Research Network (ILTER) [15]; NASA’s Carbon Monitoring System (CMS) [16]; Climate Change Initiative (CCI) [17]).

    The reduction of forest areas as well as the process of fragmentation of the forest is a ubiquitous problem worldwide. Haddad et al. estimated that half of the planet’s forests are less than 500 m from an inhabited area and most of the forested areas have an area of less than 10 hectares [18].

    The satellite images offer an unprecedented perspective on the spatial evolution of the cover surfaces with forest vegetation, allowing the mapping of the compactness of the surfaces as well as their degree of fragmentation over time [19, 20, 21, 22].

    Forest fragmentation assessments have been completed for many countries, such as Canada, China, the Democratic Republic of Congo, India, the UK, or the USA [23, 24, 25, 26]. Many of the researchers who developed these studies point out that fragmentation of forest areas has negative effects on the natural ecosystems by increasing the isolation, creating artificial margins, and reducing the basic areas of habitats.

    In Romania, forests are under pressure due to climate changes (extreme temperatures, low rainfall, strong winds, and even tornadoes) and natural disturbances (insect outbreaks), but mainly due to anthropogenic causes (various forms of property, poor pest control, illegal logging, large demands on wood for export, etc.). Although Romania’s forest area is estimated at about 29% of the country’s total area, well below the EU average level of 40%, logging is still at a high rate [27].

    A continuous, accurate, and reliable monitoring of the territorial evolution of forests as well as their state of sanogenesis is required both locally, in Romania, and regionally, Europe or worldwide. Such monitoring systems can be based on the information provided by the satellite monitoring networks correlated with on-site measurements and with accurate methods of quantification [28, 29, 30, 31, 32].

    Establishing methods of continuous observation and accurate determination of long-term environmental changes is necessary to ensure the sustainability of the forest ecosystem and the efficiency of the planned ecological restoration [33].

    The method proposed in this study wants to perform a fractal analysis regarding the deforestation of forests at the level of Romania.

    In order to start the analyses for GIS and fractal methods used, we downloaded layer (a raster image in tiff format) corresponding to the granule with the top-left corner at 50°N, 20E (in which Romania is situated), containing the forest loss (loss year) data, for the 2001–2018 [34].

    The images prepared for the fractal analyses followed a step-by-step algorithm, consisted on the extraction by mask procedure. The input feature mask was the vector limit of each relief unit of Romania, in our case 11 vector limits (the Carpathians, the Subcarpathians, the West Hills, the Danube Delta, Transylvania Depression, Dobrogea Plateau, Mehedinți Plateau, Getic Plateau, Moldova Plateau, Romania Plain, and West Plain). For each of the 11 input limits, 21 images in tiff format were exported providing pixels with useful informations. The first image exported contains the geographical limit for the relief unit, the other 18 images contain the yearly forest loss, from 2001 to 2018, and another image contains the cumulated forest loss for the entire period (2001–2018) and the last image the tree-cover information. We have to mention that for the best results, all the images exported were in black-and-white tones (the pixels corresponding to limits, to the forest loss, and to the tree cover were in white, while the background was in black color). Other important aspects were the scale and the image position: in order to avoid the information errors that might have appeared during the export processes, for each input feature mask (relief unit), the same scale and the same unmoved image position were kept.

    The exported images provided useful informations that were extracted by using some specific softwares for the fractal and nonfractal analyses. We mentioned that, depending on the surfaces of the relief units, the images were exported to different scales and analyzed later fractal objects. Thus, for the Carpathians, the exported images kept the scale 1:1,750,000; for Subcarpathians, 1:1,300,000; the Transylvanian Depression, 1:1000,000; Moldova Plateau, 1:1,500,000; Dobrogea Plateau, 1:800,000; Getic Plateau, 1:650,000; Mehedinți Plateau, 1:200,000; the West Hills, 1:1,500,000; Romania Plain, 1:1,350,000; West Plain, 1:1,500,000; and the Danube Delta, 1:600,000. Even if the exported images were analyzed at different scales, the pixel sizes being the same for each exported image, there were no distortions or errors in their subsequent processing.

    The applicability of fractal geometry is limited not only to static phenomena but also to the study of dynamic phenomena, in evolution, such as the phenomena of growth in biology or of development of urban populations [35].

    A versatile possibility to determine the deforestation patterns but also their impact on forest compaction is the fractal fragmentation index (FFI). FFI is a recent indicator and describes fractal fragmentation and can also be interpreted as an index of compaction of the analyzed surfaces, being a dimensionless indicator [36].

    The FFI is calculated using the equation (Eq. (1)):

    where FFI is the fragmentation fractal index, DA is the fractal dimension of the summed areas, and DP is the fractal dimension of the summed perimeters; ε represents the size of the box;logNε represents the number of contiguous and non-overlapping boxes needed to cover the object area; andlogN′ε represents the number of contiguous and non-overlapping boxes needed to cover only the object’s perimeter.

    When the value of the indicator has FFI=0, it means that the analyzed fractal objects (in our case the deforested areas or forests) are very small, of the order of 1–4 pixels, so that their outline cannot be extracted, DAD = DP =0. When the FFI value tends to be 1, the occupied areas are large and compact. FFI=1, when analyzing a Euclidean object, 100% compact, without any discontinuity (DP = 1 and DA = 2). When the areas occupied by the fractal are smaller, more dispersed, and more fragmented, the value of the FFI approaches more than 0. The FFI was calculated using IQM-plugin-FFI, available online at https://sourceforge.net/projects/iqmplugin-ffi/, for open source software IQM 3.5 [37].

    The analysis of the evolution of the analyzed parameter is carried out through a series of steps. In advance, IQM 3.50 software is downloaded from https://sourceforge.net/projects/iqm/files/latest/download; then, IQM-plugin-FFI is downloaded from the address https://sourceforge.net/projects/iqm-plugin-ffi/files/latest/download. The downloaded plug-in is inserted in the plug-in folder of the IQM program, and a series of steps are taken.

    Step 1: Import the images into the information quality metric (IQM – An Extensible and Portable Open Source Application for Image and Signal Analysis in Java) [File—Open Image(s)] (Figure 1).

    Importing images to analyze.

    Step 2: Convert RGB images into 8 bits [Process—Convert Image–extract G] (Figure 2).

    Convert RGB images to 8 bits.

    Step 3: Open the FFI plug-in [Plug-in—Image—FFI v2.0].

    Method P-Dimension (Pyramid Dimension) is selected (because it is much faster than box counting and the results are similar), and the number of boxes is 9; then press Preview and the fractal analysis is done (Figure 3).

    Using the FFI plug-in.

    Step 4: This gives the FFI value on the last column of the displayed table (Figure 4).

    Obtaining the results of the FFI index.

    Romania is a state located in the Southeast of Central Europe, on the lower Danube, north of the Balkan Peninsula, and on the northwestern shore of the Black Sea. The population, at the level of 2019, is estimated at 19.4 million citizens. On its territory are the southern and central parts of the Carpathian Mountains and the lower Danube basin. It borders Bulgaria to the south, Serbia to the southwest, Hungary to the northwest, Ukraine to the northeast, the Republic of Moldova to the east, and the Black Sea to the southeast (Figure 5).

    Romania—Study area.

    According to the National Institute of Statistics, Romania’s forest fund covers an area of 6,529,000 hectares, representing 27.3% of the country’s territory. The total volume of forest stands is estimated at over 1340 million m3.

    The multifunctional character of forests is given by their multiple roles: ecological, economic, and social. From a socioeconomic point of view, forest exploitation generates resources, especially wood, but it also plays an important role in the regeneration of water resources and air quality. Their use is multiple starting from the energy role (about half of the renewable energy consumed in the EU is produced from wood mass), for timber, paper industry, wood fiber panels, etc. The relationship between man and the forest is complex, and the dependence is obviously mutual.

    The territory of Romania represents a point of intersection between different biogeographic regions: Arctic, Alpine, Western and Central European, Pannonian, Pontic, Balkan, sub-Mediterranean, and even Colchian and Turanic-Iranian. This high level of diversity of ecological conditions/systems also determines a great diversity of flora and fauna, estimated at 3700 species of plants and over 33,000 species of animals. A large number of these species (over 220 plants and over 1000 animals) are endemic species, adapted to local conditions and are found only in Romania.

    Important areas of natural, virgin, and quasi-virgin forests are preserved in Romania. However, these areas are rapidly narrowing, currently occupying only about 280,000 hectares, that is, less than half of the existing area 20–25 years ago. These forests are located in a proportion of 99% in mountain regions (in karst areas, in hard-to-reach regions, on steep slopes and screes) and only in a proportion of 1% in the hill and plain regions (hard-to-reach areas of the Danube Delta or compact forest massifs located at a considerable distance from localities). Most of them are located in the area of beech and spruce and mixtures of spruce, fir, and beech. Currently, parts of the virgin and quasi-virgin forests of unique value, including for the biodiversity of natural ecosystems, are included in officially protected areas.

    The division of the property regime of the national forestry fund after the 1990s, the great dynamics of the laws in the forestry field, the lack of a coherent policy in this field, and the desire for quick financial gains generated significant deforestation of the forests at the national level. The lack of precise statistics of the deforested surfaces and the quantities of wood exploited has generated at the level of some groups of researchers or environmental organizations of solutions for the prevention and quantification of the deforested areas.

    Economic pressure and extreme environmental factors have led to the reduction of forest areas worldwide. Romania has also registered a marked dynamics of the national forestry fund in the last decades.

    The division of forest fund ownership, inadequate or poorly applied legislation, poor monitoring of the way the wood is exploited, and the occurrence of natural phenomena that have affected the forest (wind blows, biological attacks, etc.) led to the reduction of forest areas and especially to a strong fragmentation of them.

    Finding methods that determine the most precisely deforested areas, the density of the existing forest, and its territorial fragmentation is of great importance for sustainable management of the national forestry fund but also within a sustainable development of the environment (protection against landslides, floods, air quality, groundwater resources, etc.).

    The analysis was performed according to the types of relief units and their degree of forest cover. Thus, it is found that socioeconomic and natural factors of the last decades have generated a decrease of the compaction of the forest areas (Figure 6). The most affected unit of relief is that of the Carpathian Mountains and of the Mehedinți Plateau. All the relief units have suffered over time decreases of the compaction of the forest surface following the deforestation.

    Evolution of the compaction of the areas occupied by the forest, at the level of relief units, between 2001 and 2018, in Romania.

    The tested and analyzed method may also indicate the technical way of extracting the wood from the logging. A selective extraction of valuable and mature trees or a “shaved” exploitation, regardless of the size and nature of the successive species within those plots. This can be determined by comparing the obtained values of the FFI at the level of any reference year in the analyzed period.

    By performing the value difference of the FFI obtained at the level of 2018 and the one from 2001, it can be seen which relief unit was more intense and more fragmented and deforested (Figure 7).

    The degree of fragmentation of forests, obtained by comparing the value of the FFI 2018–FFI 2000.

    The area of the Carpathian Mountains, by the nature of the relief, leads to the clearing of surfaces arranged on different slopes and positions. This is also due to the access to the exploited plots and the shelving of the species. Instead, in the Romanian Plain or in the Danube Delta where the forest surfaces are composed of the same species, the exploitations are generally made from the marginal areas of the forest fund; thus, a decrease of the forested surface is recorded, but maintaining its degree of fragmentation, in general.

    If the deforestation is done on small and isolated surfaces from year to year, the values of the FFI will be zero or very close to zero. The more the deforestation is done in continuation of the previous deforestation, expanding some deforested areas spatially, the more the value of the FFI will increase.

    The Carpathian Mountains have reduced accessibility to the forest fund. In the absence of adequate exploitation technologies (funiculars, helicopters, etc.), the arrangements in the immediate vicinity of the roads are overexploited [38]. In the relief units where the forest fund is naturally fragmented and the access is much easier, we have forest exploitations on various locations (Figure 8).

    Dynamics of cumulative deforestation.

    It can be seen that the deforestation carried out within all the relief units varied from year to year. They are highlighted by the values of the annual FFI for each relief unit separately (Figure 9).

    Annual dynamics of deforestation, by relief units, between 2001 and 2018.

    Figure 10 shows the average FFI for all 18 years of analysis. The most compact deforestation, on average, took place in the Mehedinți Plateau, in the Carpathian Mountains, and in the Danube Delta. Instead, they were more fragmented in the plains and hills (Subcarpathians).

    The average of the FFI deforestation index, between 2001 and 2018 (plateau, green color; plain, yellow color; mountain and premontane units, brown color).

    Today, logging is one of the most important pressures on the natural environment, which causes major imbalances on all systemic components, the most important being the modification of microclimates [39, 40], floods, and landslides [41, 42]. In many specialized works, the need to develop methodologies for obtaining data on deforested surfaces and patterns in which they are made, especially for illegal cutting, is highlighted [43, 44, 45, 46]. Fractal analysis offers a considerable amount of information, regarding the spatial characteristics of some fractal objects, whether or not they are in dynamics. The proposed index quantifies these characteristics, being very useful in establishing patterns.

    Fractal analysis has proven to be a versatile method for evaluating the dynamics of deforestation, as well as identifying deforestation patterns; thus, it can be used complementary to the classical analyses by which data are obtained. FFI is useful in quantifying the degree of fragmentation and implicitly fractal compaction of forest areas and also provides important information on the effect of deforestation on forests, identifying also the moments of agglutination (clustering) of cumulative deforestation.

    Being a fractal index, the FFI analyses are invariant at scale, bringing a significant addition to the classical analyses, thus being relevant in the realization of strategies for forest management. The FFI was used in the analysis of deforestation in Romania and the effect of deforestation at the county level [19, 36], indicating in all cases that fragmentation of forests increases following deforestation, having negative consequences on the stability of the hydrographic network and on the habitats. Like any fractal analysis, FFI analysis has limitations. For a correct analysis, but also to be able to make comparisons, all images, which are analyzed, must be at the same resolution, scale, and position and equally binarized.

    In this study, FFI analysis allowed a clear differentiation of some patterns regarding the degree of fragmentation of the forests, but also of the compaction of the cumulative deforestation from the relief units in Romania, highlighting different dynamics. Thus, we have shown that the fragmentation of the forest is also relevant for the complex methodologies for calculating the flood risk and offers new perspectives for understanding the way in which the economic pressure on the forests is manifested.

    The research activities were financed by the projects “Spatial projection of the human pressure on forest ecosystems in Romania,” University of Bucharest, (UB/1365), and “Development of the Theory of the Dynamic Context by Analyzing the Role of the Aridization in Generating and Amplifying the Regressive Phenomena from the Territorial Systems,” Executive Agency for Higher Education, Research, Development and Innovation Funding, Romanian Ministry of Education Research Youth and Sport (UEFISCDI) (TE-2014-4-0835).

    The authors declare no conflict of interest.

    “Open access contributes to scientific excellence and integrity. It opens up research results to wider analysis. It allows research results to be reused for new discoveries. And it enables the multi-disciplinary research that is needed to solve global 21st century problems. Open access connects science with society. It allows the public to engage with research. To go behind the headlines. And look at the scientific evidence. And it enables policy makers to draw on innovative solutions to societal challenges”.

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    Open Science is transparent and accessible knowledge that is shared and developed through collaborative networks.

    Open Science is about increased rigour, accountability, and reproducibility for research. It is based on the principles of inclusion, fairness, equity, and sharing, and ultimately seeks to change the way research is done, who is involved and how it is valued. It aims to make research more open to participation, review/refutation, improvement and (re)use for the world to benefit.

    Open Science refers to doing traditional science with more transparency involved at various stages, for example by openly sharing code and data. It implies a growing set of practices – within different disciplines – aiming at:

    We aim at improving the quality and availability of scholarly communication by promoting and practicing:

     

    The Open Access publishing movement started in the early 2000s when academic leaders from around the world participated in the formation of the Budapest Initiative. They developed recommendations for an Open Access publishing process, “which has worked for the past decade to provide the public with unrestricted, free access to scholarly research—much of which is publicly funded. Making the research publicly available to everyone—free of charge and without most copyright and licensing restrictions—will accelerate scientific research efforts and allow authors to reach a larger number of readers” (reference: http://www.budapestopenaccessinitiative.org)

    IntechOpen’s co-founders, both scientists themselves, created the company while undertaking research in robotics at Vienna University. Their goal was to spread research freely “for scientists, by scientists’ to the rest of the world via the Open Access publishing model. The company soon became a signatory of the Budapest Initiative, which currently has more than 1000 supporting organizations worldwide, ranging from universities to funders.

    At IntechOpen today, we are still as committed to working with organizations and people who care about scientific discovery, to putting the academic needs of the scientific community first, and to providing an Open Access environment where scientists can maximize their contribution to scientific advancement. By opening up access to the world’s scientific research articles and book chapters, we aim to facilitate greater opportunity for collaboration, scientific discovery and progress. We subscribe wholeheartedly to the Open Access definition:

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    IntechOpen is committed to ensuring the long-term preservation and the availability of all scholarly research we publish. We employ a variety of means to enable us to deliver on our commitments to the scientific community. Apart from preservation by the Croatian National Library (for publications prior to April 18, 2018) and the British Library (for publications after April 18, 2018), our entire catalogue is preserved in the CLOCKSS archive. 

    Open Science is transparent and accessible knowledge that is shared and developed through collaborative networks.

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