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. 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 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 ].
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. 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.
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 ]. 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. 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 ]. 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. 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. 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 ]. Infection with L. 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.
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 — ].
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. 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. Another important aspect in this sector is pest control. 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 , , ]. 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 [ , ].
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 , ].
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. 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 [ — ].
Another notable example of toxin research is the use of toxins for medical treatments. For example, in studies by Lai et al. 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 [ ]. 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 [ ].
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. 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 , ].
Another alternative is the use of chemicals that inhibit the effect of bacterial toxins. 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 [ ].
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.
The authors are also grateful to Sofia Mulia for her help in preparing the English version of the manuscript of the chapter. Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.
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We are IntechOpen, the world's leading publisher of Open Access books. Built by scientists, for scientists. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. Downloaded: Abstract 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.
Keywords toxins bacteria food poisoning food-borne disease. Introduction The main pollutants can be poisons, chemical compounds, toxic gases, and bacterial toxins. Types of bacterial toxins 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.
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-ketodeoxyoctanate KDO.
Depending on their mechanism of action, exotoxins are divided as follows: Toxins Type I. Toxin type Definition Enterotoxin It produces a net secretion in ligated intestinal segments without histological evidence of intestinal lesion or damage to nonerythrocytic cells in in vitro tests.
It stimulates the increase in the short circuit current Isc and the potential difference PD in the using chamber without evidence of intestinal damage; this result involves the secretion of active electrogenic anions. Additionally, a toxin can impair electrically neutral NaCl absorption, which also results in a net secretion of ions.
Cytoskeleton-altering toxin It alters the cellular form and has been frequently shown to be caused by the F-actin rearrangement. The toxin can cause limited cell damage but is not lethal, and it may or may not be associated with the evidence of net secretion in in vivo or in vitro disease models in intestinal epithelial cells.
Cytotoxin It causes cell or tissue damage, usually ending with cell death. The toxin may or may not be associated with net secretion in in vivo or in vitro disease models in intestinal epithelial cells. Neurotoxins It involves the release of one or more neurotransmitters from the enteric nervous system. It alters the activity of smooth muscle in the intestine. Table 1. Classification of enteric toxins. Epidemiology 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.
Intrinsic parameters 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 ].
Water activity It is defined as the amount of water available for the growth of microorganisms; microbial proliferation decreases when water availability also decreases.
Content of nutrients 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. Extrinsic parameters Food factors are very important for the development of microorganisms; there are external or extrinsic factors.
Storage temperature Microorganisms have an optimal range, as well as a minimum and maximum temperature to grow. Oxygen availability and presence of other gases in the environment Like temperature, the oxygen availability determines the microorganisms that will be active.
Relative humidity in the environment 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. Presence and activities of other microorganisms Some food origin organisms produce substances that can inhibit or be lethal for other organisms; these include antibiotics, bacteriocins, hydrogen peroxide, and organic acids.
Undercooked pork, beef and poultry, contaminated eggs, and milk. Salmonella spp. Salmonellosis Salmonella Typhimurium, Salmonella Enteritidis. Undercooked poultry, cauliflowers, and tomatoes. Vibrio vulnificus Septicemia in people with underlying diseases or people who are taking immunosuppressive drugs or steroids. Seafood, usually oysters. Mycobacterium bovis Cervical lymphadenopathy, intestinal lesions, chronic cutaneous tuberculosis.
Contaminated milk. Pasteurized milk. Listeria monocytogenes Meningitis, encephalitis, sepsis in pregnant women, intrauterine or cervical infection that can lead to miscarriage or birth of a dead child.
Raw beef, pork, poultry, vegetables and milk, cheese, ice cream, smoked fish, and raw fish. Table 2. Pathogens that cause infection. Mixture of oil and nonacid garlic, potatoes cooked at high temperatures, and stews. Bacillus cereus Fried rice syndrome.
Rice cooked at high temperatures, sauces, soups, and puddings. Staphylococcus aureus Toxic shock syndrome. Meat and meat products cooked at high temperatures, poultry, and salads with mayonnaise. Table 3. Pathogens that cause intoxication. Hamburgers, nonpasteurized milk, contaminated water, spinach, and lettuce. Shigella spp. Hemolytic Uremic Syndrome. Science News. Story Source: Materials provided by Quadram Institute. Carter, Sandra C. Stringer, Michael W.
Identification of a novel botulinum neurotoxin gene cluster in Enterococcus. ScienceDaily, 12 January Quadram Institute. Retrieved November 10, from www. The research shows how optogenetic technology can be used to investigate That inhibiting compound, nitrophenyl psoralen NPP , could be used as a treatment Botulinum toxins are widely used to treat a growing list of medical ScienceDaily shares links with sites in the TrendMD network and earns revenue from third-party advertisers, where indicated.
Dong's laboratory. When the research team tested the toxin in rodents in the lab, it had little or no effect. Only when they manipulated the toxin to better target mouse and rat neurons did it become potent, shutting down nerve function and causing paralysis.
Additionally, the researchers were curious to determine exactly how the botulinum toxin jumped from one bacterial species to another. Plasmids are mobile structures that contain DNA independently of the chromosomes and can be swapped from one bacterium to another. Plasmids are quite common in enterococci —in fact, they have been associated with the acquisition of resistance to vancomycin, a last-resort antibiotic, and transfer of resistance to the fearsome Staphylococcus aureus.
Enterococcus faecium carries a conjugative plasmid encoding a BoNTlike toxin gene. Thus, a commensal organism can acquire and possibly disseminate BoNT genes. This ability to swap genes is what worries many researchers. Could a potent toxin from C. Many investigators now seem to think that it is at least theoretically possible. Dong remarked. With current technology being what it is today, the research team was able to rapidly sequence the toxin-producing E.
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