Bacillus Cereus ( Mehrdad Tajkarimi )
Bacillus cereus
Mehrdad Tajkarimi
Materials from Maha Hajmeer
Introduction:
Bacillus cereus is a Gram-positive, spore-forming microorganism capable of causing foodborne disease At present three enterotoxins, able to cause the diarrheal syndrome, have been described: hemolysin BL (HBL), nonhemolytic enterotoxin (NHE) and cytotoxin K. HBL and NHE are three-component proteins, whereas cytotoxin K is a single protein toxin. Symptoms caused by
the latter toxin are more severe and may even involve necrosis. In general, the onset of symptoms is within 6 to 24 h after consumption of the incriminated food. B. cereus food poisoning is underestimated probably because of the short duration of the illness (~24 h).
History
In 1887, Bacillus cereus isolated from air in a cowshed by Frankland and Frankland. Since 1950, many outbreaks from a variety of foods including meat and vegetable soups, cooked meat and poultry, fish, milk and ice cream were described in Europe. In 1969, the first well-characterized B. cereus outbreak in the USA was documented. Since 1971, a number of B. cereus poisonings of a different type, called the vomiting type, were reported. This type of poisoning was characterized by an acute attack of nausea and vomiting 1–5 h after consumption of the incriminated meal. Sometimes, the incubation time was as short as 15–30 min or as long as 6–12 h. Almost all the vomiting type outbreaks were associated with consumption of cooked rice. This type of poisoning resembled staphylococcal food poisoning.
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