Difference between revisions of "Bacillus cereus"

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Revision as of 06:43, 4 August 2015

Background

  • Gram-positive, beta-hemolytic, rod-shaped bacterium
  • Known for causing foodborne illness in humans, though some strains are probiotic
  • Classically associated with "fried rice syndrome"

Pathogenesis

B. cereus is responsible for a minority of foodborne illnesses, causing severe nausea, vomiting, and diarrhea.[1] Bacillus foodborne illnesses occur due to survival of endospores when food is improperly cooked. Bacterial growth results in production of enterotoxins, one of which is heat- and acid-stable (pH 2 to 11); ingestion leads to two types of illness: diarrheal and emetic.

  • The diarrheal type is associated with a wide range of foods, has an 8-16 hour incubation time, and is associated with diarrhea and gastrointestinal pain.
  • The emetic form is commonly caused by rice cooked for a time and temperature insufficient to kill any spores present, then improperly refrigerated. It can produce a toxin which is not inactivated by later reheating. This form leads to nausea and vomiting one to five hours after consumption. It can be difficult to distinguish from other short-term bacterial foodborne intoxications such as by Staphylococcus aureus.

Prognosis

Most emetic patients recover within six to 24 hours but in some cases, the toxin can be fatal.[2]

References

  1. Kotiranta A, Lounatmaa K, Haapasalo M (2000). "Epidemiology and pathogenesis of Bacillus cereus infections". Microbes Infect 2 (2): 189–98. doi:10.1016/S1286-4579(00)00269-0. PMID 10742691.
  2. Takabe F, Oya M (1976). "An autopsy case of food poisoning associated with Bacillus cereus". ForensicSci 7 (2): 97–101.