Difference between revisions of "Bacillus cereus"

(added image)
Line 1: Line 1:
 
==Background==
 
==Background==
*[[Gram-positive]], beta-hemolytic, rod-shaped bacterium
+
*Gram-positive, beta-hemolytic, rod-shaped bacterium
 
*Known for causing foodborne illness in humans, though some strains are probiotic
 
*Known for causing foodborne illness in humans, though some strains are probiotic
 
*Classically associated with "fried rice syndrome"
 
*Classically associated with "fried rice syndrome"
*8-16 hour incubation time
+
[[File:bcereus.png|thumb|B. cereus growing on blood agar]]
  
===Pathogenesis===
+
==Pathogenesis==
*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.
+
B. cereus is responsible for a minority of foodborne illnesses, causing severe nausea, vomiting, and diarrhea.<ref> 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.</ref>  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.
*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.
==Clinical Features==
 
*Causes severe [[nausea]], [[vomiting]], and [[diarrhea]].<ref> 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.</ref>
 
 
 
==Differential Diagnosis==
 
{{Diarrhea DDX}}
 
 
 
==Management==
 
Primarily supportive/symptomatic treatment, as most patients recover.
 
  
 
==Prognosis==
 
==Prognosis==
*Most emetic patients recover within 6-24 hours
+
Most emetic patients recover within six to 24 hours but in some cases, the toxin can be fatal.<ref> Takabe F, Oya M (1976). "An autopsy case of food poisoning associated with Bacillus cereus". ForensicSci 7 (2): 97–101.</ref>
**In some rare cases, the toxin can be fatal.<ref> Takabe F, Oya M (1976). "An autopsy case of food poisoning associated with Bacillus cereus". ForensicSci 7 (2): 97–101.</ref>
 
 
 
==Table Overview==
 
{{Clinically Relevant Bacteria}}
 
 
 
==See Also==
 
*[[Microbiology (Main)]]
 
  
 
==References==
 
==References==
<references/>
+
<references />
 
 
[[Category:ID]]
 

Revision as of 20:21, 17 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"
B. cereus growing on blood agar

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.