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Foodborne Intoxication and Toxicoinfections

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    Vindhya Tri Widayanti, STP., MP.

    Foodborne Intoxication andToxicoinfections

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    Foodborne IntoxicationsFood Microbilogy

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    Foodborne IntoxicationFoodborne intoxication or food poisoning ofmicrobial origin occurs by ingesting a foodcontaining a preformed toxinFoodborne intoxication

    Staphylococcal intoxicationBotulismMycotoxicosis

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    Some General Characteristics1. The toxin is produced by a pathogen while growing

    in a food.2. A toxin can be heat labile or heat stable.3. Ingestion of a food containing active toxin, not viable

    microbial cells, is necessary for poisoning (exceptfor infant botulism, in which viable spores need tobe ingested).

    4. Symptoms generally occur quickly, as early as 30min after ingestion.

    5. Symptoms differ with type of toxin; enterotoxinsproduce gastric symptoms and neurotoxins produceneurological symptoms.

    6. Febrile symptom is not present.

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    Staphylococcal intoxication

    Foodborne Intoxication

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    Staphylococcal intoxicationIMPORTANCEStaphylococcal food poisoning(staphylococcal gastroenteritis;

    staphylococcal food poisoning; staph foodpoisoning), caused by toxins ofStaphylococcus aureus, is considered one ofthe most frequently occurring foodborne

    diseases worldwide. 1,2

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    Characteristics of Staphy lococcusaureus Organ isms

    Sta. aureus are Gram-positive cocci, occur generally in bunches, andare nonmotile, noncapsular, and nonsporulating

    G r o w thMost strains ferment mannitol and produce coagulase, thermonuclease,and hemolysin, but differ in their sensitivity to bacteriophages.The cells are killed at 66C in12 min, and at 72C in 15 s.Sta. aureus are facultative anaerobes, but grow rapidly under aerobicconditions.They can ferment carbohydrates and also cause proteolysis byextracellular proteolytic enzymes.

    They are mesophiles with a growth temperature range of 7 to 48C, withfairly rapid growth between 20 and 37C.They can grow at relatively low Aw (0.86), low pH (4.8), and high saltand sugar concentrations of 15% and in the presence of NO2.Sta. aureus can grow in many foods.

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    Characteristics of Staphy lococcusaureus Habitat

    Sta. aureus, along with many other staphylococci,are naturally present in the nose, throat, skin, andhair (feathers) of healthy humans, animals, andbirds.Sta. aureus can be present in infections, such ascuts in skin and abscesses in humans, animals,and birds, and cuts in hands and facial-eruptedacne in humans.Food contamination generally occurs from thesesources

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    Toxins and Toxin Production Enterotoxigenic strains of Sta. aureus produce sevendifferent enterotoxins: A, B, C1, C2, C3, D, and E (alsodesignated as SEA, SEB, etc.).They are serologically distinct heat-stable proteins ofmolecular weight 26 to 30 kDa and differ intoxicity. Thetoxins vary in heat stability, SEB being more stable thanSEA.Normal temperature and time used to process or cookfoods do not destroy the potency of the toxins. Outbreaksfrom SEA are more frequent, probably because of its highpotency.

    Rate of toxin production by a strain is directly related to itsrate of growth and cell concentrations. Optimum growthoccurs ca. 37 to 40C. Under optimum conditions of growth,toxins can be detected when a population has reachedover a few million per gram or milliliter of food andgenerally in ca. 4 h.Some of the lowest environmental parameters of toxin

    roduction are 10C H 5.0 or Aw 0.86

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    Disease and Symptoms Staphylococcal toxins are enteric toxins and causegastroenteritis.

    A healthy adult has to consume ca. 30 g or ml of afood containing 100 to 200 ng toxins produced by

    106 7 cells/g or /ml; infants and old and sickindividuals need lesser amounts.The symptoms occur within 2 to 4 h, with a range of30 min to 8 h, and are directly related to the potency

    and amounts of toxin ingested and an individualsresistance.The primary symptoms, from stimulation of theautonomic nervous system by the toxins, are

    salivation, nausea and vomiting, abdominal cramps,and diarrhea. Some secondary symptoms are

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    Food Association

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    Prevention (Reduction) of theDisease

    Reduce initial load of Sta. aureus in a food by properselection of the quality of the raw materials andingredientssanitation of the food environments

    proper personal hygiene among food handlers.People with respiratory diseases, acute types of facialacne, skin rash, and cuts in hands should not handlethe food.products should be heat-treated to ensure killing oflive cells.chill the processed products and ready-to-eat foods to5C quickly.Suitable preservatives can also be used to kill or

    arrest growth.Once heatstable toxins are formed, heatin before

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    Identification Methods To associate a food implicated in staphylococcal food poisoning, thefood or vomit samples are analyzed for the presence of high levels ofenterotoxigenic Sta. aureus cells and enterotoxins.Enumeration technique in one or more selective differential agar mediato determine the load of viable cells of Sta. aureus, followed by severalbiochemical tests, such as hemolysis, coagulase, thermonucleasereactions, or ability of a pure culture to produce enterotoxin, areperformed to link the potential cause of the food poisoning outbreaks.Enterotoxins from the food or vomit samples are extracted and tested,either by biological means or by serological means, to associate themwith the outbreak. In the biological method, animals (e.g., cats,monkeys, or dogs) are given the enterotoxin preparation orally or it isinjected intraperitoneally or intravenously. Vomiting symptoms by thetest animals is a positive indication of the presence of staphylococcalenterotoxin.In the serological methods, the enterotoxins are purified and examinedby one of the several recommended immunological methods. Not onlyare these tests very sensitive, but they allow the identification of thetypes of enterotoxins involved in a food poisoning case.

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    BotulismFoodborne Intoxication

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    BotulismBotulism results following consumption of foodcontaining the potent toxin botulin of Clostridiumbotulinum. It is a neurotoxin and producesneurological symptoms along with some gastricsymptoms. Unless prompt treatment isadministered, it is quite fatal. Infant botulismoccurs when an infant ingests Clo. botulinumspores, which germinate, grow, and producetoxins in the GI tract and cause specificsymptoms.

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    CharacteristicsOrgan isms

    Cells of Clo. botulinum strains are Gram-positiverods, occur as single cells or in small chains;many are motile, obligate anaerobes, and form

    single terminal spores.Cells are sensitive to low pH (

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    CharacteristicsGrowth

    Clo. botulinum strains, on the basis of the type of toxin production, have been divided into six types: A, B, C, D, E,and F. Of these, A, B, E, and F are associated with humanfoodborne intoxications.

    Type A strains are proteolytic, Type E strains arenonproteolytic, but Types B and F strains can be eitherproteolytic or nonproteolyticProteolytic strains can grow between 10C and ca. 48C,with the optimum at 35C.Nonproteolytic strains grow optimally at 30C, with a rangefrom 3.3 to 45C.Optimum growth facilitates optimum toxin production. A pH of 4.6, Aw of 0.93, or 5.5% NaCl can prevent cellgrowth, but by using two or more parameters along withlower temperature, the lower growth limits of any of the

    given parameters can be greatly reduced

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    CharacteristicsHabitat

    Spores of Clo. botulinum are widely distributed insoil, sewage, mud, sediments of marshes, lakesand coastal waters, plants, and intestinal contentsof animals and fishes.Fruits and vegetables can be contaminated withspores from soil, fishes from water andsediments, and various other foods from many ofthe given sources.Type A and B spores are more prevalent in soil,sewage, and fecal matters of animals, whereas

    Type E spores are generally found in marineenvironments.

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    Toxins and Toxin ProductionThe toxins of Clo. botulinum are neurotoxic proteins.In general, toxins associated with food intoxication in humans (Types A,B, E, and F) are extremely potent, and only a small amount of toxin isrequired to produce the symptoms and cause death.Following ingestion, toxin molecules are absorbed from the upperportion of the intestine through the intestinal wall and spread via theblood to the peripheral nerves. The toxins block signal transfers,irreversibly causing paralysis of all involuntary muscles. The toxinsmove slowly through the body.Toxins produced by nonproteolytic strains are not fully activated; trypsintreatment is necessary to activate them (this occurs in the digestivetract).The toxins are heat labile and can be destroyed in a contaminated food

    by high and uniform heat, such as 90C for 15 min or boiling for 5 min.Radiation at 5 to 7 mrad can also destroy themCell growth is necessary for toxin production. At optimum growthtemperature, toxins are produced in large amounts. However, at bothextreme growth ranges, enough toxin can be produced by a strain in afood to cause disease and death following ingestion.

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    Disease and SymptomsBotulism is caused by ingestion of the neurotoxin botulinformed in a food. The toxins are absorbed from theintestine, spread to the peripheral nerves, and block thetransmission of impulse.However, at the initial stage (generally 12 to 36 h, butcanbe 2 h), some gastrointestinal disorders (e.g., nausea,vomiting, diarrhea, and constipation) may be evident. Neurological symptoms develop within a short time,especially if the amount of botulin consumed is high. Asthey are highly potent toxins, only a very small amount (1ng/kg body weight) is necessary for severe symptoms and

    even death.In general, neurological symptoms include blurred ordouble vision; difficulty in swallowing, breathing, andspeaking; dryness of the mouth; and paralysis of differentinvoluntary muscles, which spreads to the diaphragm,lungs, and heart.

    Death usually results from respiratory failure.

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    Food Association

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    Prevention of BotulismThe single most important control method is to useproper temperature and time in home canning of low-acid products.Some foods (e.g., fish) should be properly anduniformly cooked at high temperatures.

    Foods cooked at temperatures in which sporessurvive should be stored at low temperatures (at 3Cor below); at refrigerated temperature (4 to 5C),storage should not be prolonged unless someadditional precautions are used, such as NO2, low

    pH, low Aw, or NaCl.Suspected foods should be properly heated beforeconsumption, but it is better not to eat them.Even tasting a small amount of a suspected foodwithout giving high and uniform heat treatment can be

    dangerous

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    Identification MethodsIn a suspected food, the presence of Clo.botulinum can be determined by enumerationtechniques using selective agar media andanaerobic incubation, followed by biochemicaland toxicological testing.The presence of toxins in the food is more oftentested. This involves injecting a food extractintraperitoneally into mice. Development ofcharacteristic neurological symptoms, followed bydeath in 92 h, suggest the presence of toxin.The people engaged in testing for the organismor the toxins need to immunize themselves beforehandling the materials

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    Infant BotulismClo. botulinum spores, ingested by human infantsthrough food and the environment, can germinate inthe intestine and produce the toxin to cause infantbotulism. The spores fail to produce the same disease inindividuals above 1 year of age, probably because thewell-established normal population of gastrointestinalflora discourages spore germination and cellmultiplication by Clo. botulinum.

    Both Types A and B have been identified in infantbotulism cases. Symptoms include general weakness,inability to suck and control the head, loss of reflexes,and constipation.Foods such as honey and corn syrup and dirt havebeen linked as sources of Clo. Botulinum spores in

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    MycotoxicosisFoodborne Intoxication

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    MycotoxicosisMany strains of molds, while growing in a suitableenvironment (including in foods), producemetabolites that are toxic to humans, animals,and birds, and are grouped as mycotoxins.Consumption of foods containing mycotoxinscauses mycotoxicosis. They are secondarymetabolites and not proteins or enteric toxins.Many are carcinogens and, when consumed, cancause cancer in different tissues in the body.Some cause toxicity of organs by unknownmechanisms.

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    CharacteristicsGrowth

    In general, molds grow best in humid and warmenvironments. They are aerobic and thus need airfor growth.They can grow, though slowly, at very low Aw(0.65), low temperature (refrigeratedtemperature), and low pH (pH 3.5). Theseconditions are often used to extend the shelf lifeof many foods.Unless other methods (such as vacuumpackaging) are used, they can grow in thesefoods, and, if toxigenic, can produce toxins in thefoods

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    CharacteristicsHabitat

    The spores are present in soil, dust, and theenvironment. Many foods can have viable sporesor mycelia, especially before a heat treatment

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    Toxins and Toxin Production Mycotoxins include a large number of toxins produced bydifferent toxigenic species and strains of molds.Many have not yet been identified.Some of the toxins have been listed before. They aresmall-molecular-weight heterocyclic organic compoundsand some have more than one chemical type. An exampleis aflatoxin, which has two major types, B1 and G1, andeach has several subtypes. Aflatoxin B1 is considered themost potent.Mycotoxins are produced by toxigenic mold strains assecondary metabolites.

    Toxin production, in general, is directly related with thegrowth rate of a mold strain.In microbiological media suitable for growth of molds, Asp.flavus strains can produce optimum concentrations ofaflatoxin at 33C, pH 5.0, and Aw 0.99.

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    Food Association The growth of toxigenic mold strains and thepresence of specific mycotoxins have been detectedin many foods, such as corn, wheat, barley, rye, rice,beans, peas, peanuts, bread, cheeses, dry sausages,spices, apple cider, grain meals, dough cassava,cotton seeds, and spaghetti.Consumption of mycotoxin-contaminated food cancause mycotoxicosis in humans.Feeding moldy products to food animals (includingmoldy silage) and birds can also produce foods ofanimal origin (milk, eggs) that are contaminated withmycotoxins.Many mycotoxins are resistant to heat used in thenormal preparation of foods. Thus, their elimination byheating is not used to remove them from foods.

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    Prevention of Mycotoxicosis Heat treatment, where possible, can also reducethe load by killing the molds and their spores.Using anaerobic packaging;reducing Aw, where possible, to 0.6 or below;freezingusing specific preservatives against mold growth.

    A product in which molds have grown should not

    be consumed.

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    Detection Methods These include solvent extraction of a suspectedfood sample, thin layer chromatography of theextract, and visualizing under a UV light or afluorescent light.

    Chemical tests and analysis by mass spectralmethods are used to identify the specific type ofaflatoxin

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    Foodborne ToxicoinfectionFood Microbiology

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    Foodborn Toxicoinfection1. For sporeformers, ingestion of large numbers of

    live vegetative cells is usually necessary.2. Vegetative cells of sporeformers do not multiply

    in the digestive tract, but sporulate and releasetoxins.

    3. For Gram-negative bacteria, live cells can beingested in moderate numbers.

    4.Gram-negative cells rapidly multiply in thedigestive tract.

    5. Many cells also die, releasing toxins.6. Toxins of both groups produce the

    gastroenteritis symptoms.

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    Clos t r id ium Perf r ingens Gas t ro enter i ti s Foodborne Toxicoinfection

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    Clos t r id iu m Perf r ingensGastroenter i t is

    Gastroenteritis caused by Clo. perfringens hasseveral specific characteristics. In most outbreaks,large numbers of cases are involved.The outbreaks generally occur with some foods thatwere prepared in advance by heating and then keptwarm for several hours before serving. In the majorityof the instances, these situations are associated withfeeding many people within a short period of time incafeterias, restaurants, schools, and banquets(banquet disease).

    As the disease produces mild symptoms, manyincidents are probably not reported. Thus, thereported cases could be only a fraction of the actualnumbers

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    CharacteristicsThe cells are Gram-positive rods, motile, and sporeformers.Cells vary in size and can form small chains.Clo. perfringens is anaerobic but can tolerate some air (oxygen).The vegetative cells are sensitive to low-heat treatment(pasteurization), but the spores are extremely heat resistant, andsome can survive even boiling for several hours.The cells are resistant to D-cycloserine.In the presence of suitable substrates, H2S is formed duringgrowth.The cells need several amino acids for growth. Thus, they cangrow very effectively in many protein foods.

    The temperatures of growth of vegetative cells and germinationof spores and outgrowth range between 10 and 52C. Theoptimum growth occurs at ca. 45C.

    At optimum conditions, cell multiplication can be very rapid, inca. 9 min.The cells fail to grow well at pH 5%,

    at Aw,

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    Toxin and Toxin Production Among the five types of Clo. perfringens, Type Astrains are predominantly involved in foodbornetoxicoinfection.The enterotoxin is a heat-labile protein. It is an

    intracellular protein produced by the cells duringsporulation in the intestine and released. Unliketoxins of foodpoisoning microorganisms, theenterotoxin is produced in the digestive tract.The environmental parameters for the productionof enterotoxin are directly related to thesporulation environment. There are some reportsthat, in addition to the intestine, sporulation andenterotoxin production to certain levels can also

    occur in some foods

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    Disease and SymptomsThe enterotoxin causes only gastroenteritis.The symptoms appear 8 to 24 h followingingestion of a large number of viable cells ( 5 -105/g) through a food. The main symptoms are diarrhea and abdominalpain. Nausea, vomiting, and fever also can occurbut are less common.The toxin changes the permeability of intestinalcells.

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    Food AssociationRaw meat from animals and birds is mostcommonly contaminated with the spores and cellsfrom the digestive tract content,vegetables and spices commonly get them fromsoil and dust.

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    Preventionproper sanitation in all phases of food preparationand handling.Food should be cooked to the highesttemperature recommended to kill the cells and asmany spores as possible.The food should be cooled quickly and uniformly(preferably within 1 h) to refrigerated temperature

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    Detection MethodThe detection method involves enumeration ofthe incriminated food and fecal samples for Clo.

    perfringens in a selective agar medium andincubation of plates under anaerobic conditions.

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    B aci l lus cereus Gastro enter i t is Foodborne Toxicoinfection

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    B aci l lus cereu s Gast ro en ter i t i s The incidence of foodborne gastroenteritis byBac. cereus origin is relatively high in someEuropean countries..

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    Characteristics The cells are Gram-positive motile rods, whichform endospores in the middle of the cells.Cells are sensitive to pasteurization.Spores can survive high heat treatment used in

    many cooking procedures.Bac. cereus is aerobic, but can also grow undersome degree of anaerobic environment.The cells can multiply in a temperature range of 4

    to 50C, with the optimum ca. 35 to 40C.Other parameters of growth are pH of 4.9 to 9.3,

    Aw of 0.95 and above, and NaCl concentrationbelow 10%.

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    HabitatSpores and cells of Bac. cereus are common insoil and dust and can be readily isolated in smallnumbers from many foods, which include bothraw and finished products. Intestinal tracts of 10%

    of healthy adult humans have Bac. cereus undernormal conditions.

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    Toxins and Toxin Production The strains produce at least two types (emeticand enteric) of enterotoxins, eachprobably associated with specific types ofsymptoms.3,6 The toxins are produced

    during growth of cells at the growth temperaturerange and retained in the cells.Only when the cells are lysed are the toxinsreleased. They occur in the intestinal

    tract but can also occur in foods. Thus, the casescan also be regarded as foodpoisoning, as in staphylococcal food poisoning

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    Disease and Symptoms In general, a large number of cells (10^6 8/g) need to beingested to produce gastroenteritis.The two types of enterotoxins produce two types of symptoms.The enterotoxin associated with the diarrheal form is a heat-labile protein, and that associated with the emetic form is a heat-stable protein.

    In the diarrheal form, symptoms occur 6 to 12 h followingconsumption of a food containing the viable cells. Symptomsinclude abdominal pain, profuse watery diarrhea, and perhapsnausea, but no vomiting or fever. Recovery is usually within 24 h.These symptoms in many respects are similar to those producedby Clo. perfringens.

    In the emetic form, the symptoms occur 1 to 5 h followingingestion of a food containing the viable cells. As the toxin is heatstable, once the toxin forms in cells, heating food containing alarge number of cells before eating can produce the symptoms.Symptoms are nausea and vomiting; abdominal pain anddiarrhea may also be present. Symptoms last for ca. 24 h. Insome respects, the symptoms are similar to those ofstaphylococcal gastroenteritis.

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    Food Association

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    Prevention Heat treatmentDecrease contaminated equipment,Personal hygiene.Keep food at a temperature at which the sporesdo not germinate and cells do not grow.

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    Detection Method Bac. cereus can be enumerated by surface

    plating on an agar medium containing mannitol,egg yolk, and polymyxin B (as a selective agent).Colonies surrounded by precipitation resultingfrom lecithinase of the cells are indicative of Bac.cereus.

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    CholeraFoodborne Toxicoinfection

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    CholeraCholera, caused by Vib. cholerae 01, is anoncontagious disease but can cause largeepidemics with high mortality.

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    Characteristics Vib. cholerae, like other vibrios, is a Gram-negative motile,curved rod. The species has many serogroups.Strains in 01 are associated with epidemic cholera. Thisserotype is further characterized by biotype and serotype.The type currently associated with cholera epidemicsworldwide is of the El Tor biotype and either Inaba orOgawa serotype.Non-01 serotypes do not agglutinate with antibodiesprepared against 01 antigens. Also, non-01 serotypes,similar to 01 serotypes, are not sensitive to trimethoprim-sulfamethoxazole with furazolidone.

    Both types are sensitive to heat and are killed by thetemperature used for cooking. Improper heating (at lowertemperature for a shorter time) may not be able to kill allthe cells present in a food.The optimum temperature of growth is between 30 and35C. The growth rate is very rapid, even at room

    temperature.

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    Habitat Cholera is a human disease. The disease resultsfrom the ingestion of infective doses of Vib.cholerae cells through food and watercontaminated with feces of humans suffering from

    the disease.

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    Toxins and Toxin Production The toxin of the 01 serotype

    a heat-labile 85-kDa cytotoxic protein with two functional units.The active A subunit stimulates adenyl cyclase in theintestinal epithelial cells, causing massive secretion ofwater along with chloride, potassium, and bicarbonate inthe lining of the intestine.

    The non-01 serotypeproduces a cytotoxin and a hemolysin.Following ingestion of Vib. cholerae cells in sufficientnumbers,the cells colonize the small intestine and multiply rapidlyand produce toxins.When the cells die and lyse, the toxins are released intothe intestine.

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    Disease and Symptoms Vib. cholerae is not contagious. A person must consume a largenumber of viable cells through contaminated food or water tocontract the disease.The infective dose for cholera is ca. 10^6 viable cells per person,but it varies with age and health.The incubation period ranges from 1 to 5 d, but is usually 2 d.

    The symptoms include the sudden onset of profuse waterydiarrhea and vomiting. Loss of fluid results in dehydration.Other symptoms in severe cases are painful muscle cramps andclouded mental status.Many infected persons may not have any symptom or have mildto moderate diarrhea.Treatments consist of rapid replacement of fluids, along withelectrolytes, and administration of proper antibiotics.In addition to diarrhea, the non-01 toxins also cause infection ofsoft tissues and septicemia.

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    Food Association

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    Detection Method Isolation of Vib. cholerae from a sample isachieved by an initial preenrichment in alkalinepeptone water, followed by streaking on aselective agar medium plate (such as thiosulfate

    citrate bile salt sucrose agar).Suspected colonies (yellow) are biochemicallyand serologically tested for confirmation. Thetoxin is detected by immunoassay or bioassay.

    The toxin gene can be identified by PCR.

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    Esch erichia co l i Gastro enter i t is Foodborne Toxicoinfection

    Esch er ich iaco l i

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    Esch er ich ia co l iGastroenter i t is

    The two (of the four) enteropathogenic Esc. colisubgroups that correlate well with toxicoinfectionprobably belong to the enteropathogenic andenterotoxigenic Esc. coli (EPEC and ETEC,

    respectively) types.They produce diarrheal diseases when ingestedin large numbers through contaminated foods andwater.

    The symptoms are more like those in cholera.The incidence is high in many developingcountries and is directly related to poor sanitation.

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    Characteristics Gram-negative small curved rods, nonsporulatingand motile (nonmotile strains can be present).The strains are facultative anaerobes and cangrow effectively in both simple and complex

    media and many foods.Growth occurs between 10 and 50C,withoptimum at 30 to 37C. Some strains can growbelow 10C. Rapid growth occurs under optimumconditions.Growth-limiting factors are low pH (below 5.0)and low Aw (below 0.93).The cells are sensitive to low-heat treatment,such as pasteurization.

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    Toxins and Toxin Production The strains in the ETEC subgroup produce twotypes of enterotoxins: one is heat labile (LT) andthe other is heat stable (ST). A strain can produceeither LT or ST, or both. LT toxin is an antigenic

    protein, similar to cholera toxinST is a heat-stable protein, lower in molecularweight than LT, and is nonantigenic. It alsoincreases fluid secretion by intestinal cells, but

    through a different mode of action.

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    Toxins and Toxin Production Strains in EPEC subgroups not to produce enterotoxinssuch as those by ETEC serotypes.Some studies have shown that several serotypes produceLT toxin, and several others produce toxins different fromLT and ST of ETEC serotypes.

    ETEC serotypes can also produce additional factors thatenable the cells to colonize, multiply, and initiate infection.The genetic determinants of the enterotoxins in ETEC areplasmid linked and can be transferred to other Esc. colistrains.

    The production of enterotoxins by ETEC strains isinfluenced by media composition, culture age, andalteration of a culture during growth. Optimum productionoccurs in a nutritionally rich medium at pH 8.5. Aeration ofbroth facilitates good toxin production. The toxins aregenerally detected in a growing culture within 24 h at 35C.

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    Disease and Symptoms EPEC strains were initially thought to be associatedwith infant diarrhea in many tropical and developingcountries, causing high mortality.In contrast, ETEC strains are regarded as the cause

    of travelers diarrhea, a nonfatal diarrheal disease.Ingestion of a high level (10^6 9 cells) of viable cellsof the organisms by adults is necessary for thesymptoms to occur within 24 to 72 h.

    Symptoms include mild to severe diarrhea that lastsfor 24 to 30 h. In severe cases, dehydration,prostration, and shock may accompany the diarrhea.Not all individuals show symptoms

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    Food Association Many types of foods, including meat products,fish, milk and dairy products, vegetables, bakedproducts, and water have been associated withgastroenteritis of Esc. coli origin in many

    countries. These include serotypes from bothEPEC and ETEC subgroups.

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    Prevention Heat treatment

    prevent contamination of food and water, directlyor indirectly, by fecal matters.developing effective sanitation in water suppliesand treating and disposing sewage.prevent contamination of food due to poorpersonal hygiene by people who shed thepathogen.food should be refrigerated or eaten quickly,preferably after reheating

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    Food Microbiology

    Thank You


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