Lecture%207-new

Lecture%207-new - Endospore forming pathogens Form spores...

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Endospore forming pathogens Form spores (dormant,very resistant) 3 groups Endospores Survive conventional cooking Soil bacteria Poor competitors Intoxications Control
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B. anthracis Anthrax 3 types Capsule or toxin B. cereus Digests starch and protein very vigorously Emetic toxin Enterotoxin Control: storage and reheat
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Clostridium perfringens : One of the most common food borne illnesses in the U.S The organism: Gram +ve anaerobe
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a. C. perfringens proliferate in animal intestines b. Commonly found in meat and soil c. THERMOPHILE: Grows well 45-50°C (110-125°F) vegetative cells survive up to 60°C (140°F) d. Proliferates in cooked food held very warm for long periods e. Produces many kinds of extracellular enzymes, particularly well-suited to digesting proteins, grows well in meat dishes f. Produces a protein during sporulation acts as an enterotoxin in human intestines gastroenteritis
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The disease Vegetative cells ingested proliferate sporulate Intestines generation exceedingly short (<15 mins) population size grows quickly Produce enterotoxin as a byproduct of sporulation reactions Does not colonize the intestines, produces toxin during its passage sick
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Food poisoning is an infection, with toxin- mediated virulence (the organism itself, rather than pre-formed toxin, is ingested and elaborates toxin)
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Not really an infection : Colonization does not occur Not really an intoxication : Toxin is made in us “disease without colonization” Minimum dose of vegetative cells: 10 6 -10 7 cells Incubation period: 6-12 hrs (sometimes up to 24hrs) Symptoms: typical gastroenteritis Illness duration: 12-24 hrs
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Enterotoxin binds to a single type of receptor on target host cells
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Lecture%207-new - Endospore forming pathogens Form spores...

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