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| The Bad Bug Book |
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1. Name of the Organism:
Bacillus cereus and other Bacillus spp.
Bacillus cereus is a Gram-positive, facultatively aerobic sporeformer
whose cells are large rods and whose spores do not swell the
sporangium. These and other characteristics, including biochemical
features, are used to differentiate and confirm the presence B. cereus,
although these characteristics are shared with B. cereus var. mycoides,
B. thuringiensis and B. anthracis. Differentiation of these organisms
depends upon determination of motility (most B. cereus are motile),
presence of toxin crystals (B. thuringiensis), hemolytic activity (B.
cereus and others are beta hemolytic whereas B. anthracis is usually
nonhemolytic), and rhizoid growth which is characteristic of B. cereus
var. mycoides.
2. Nature of Acute Disease:
B. cereus food poisoning is the general description, although two
recognized types of illness are caused by two distinct metabolites. The
diarrheal type of illness is caused by a large molecular weight protein,
while the vomiting (emetic) type of illness is believed to be caused by a
low molecular weight, heat-stable peptide.
3. Nature of Disease:
The symptoms of B. cereus diarrheal type food poisoning mimic those of
Clostridium perfringens food poisoning. The onset of watery diarrhea,
abdominal cramps, and pain occurs 6-15 hours after consumption of
contaminated food. Nausea may accompany diarrhea, but vomiting
(emesis) rarely occurs. Symptoms persist for 24 hours in most
instances.
Bacillus cereus and other Bacillus spp.
Bacillus cereus is a Gram-positive, facultatively aerobic sporeformer
whose cells are large rods and whose spores do not swell the
sporangium. These and other characteristics, including biochemical
features, are used to differentiate and confirm the presence B. cereus,
although these characteristics are shared with B. cereus var. mycoides,
B. thuringiensis and B. anthracis. Differentiation of these organisms
depends upon determination of motility (most B. cereus are motile),
presence of toxin crystals (B. thuringiensis), hemolytic activity (B.
cereus and others are beta hemolytic whereas B. anthracis is usually
nonhemolytic), and rhizoid growth which is characteristic of B. cereus
var. mycoides.
2. Nature of Acute Disease:
B. cereus food poisoning is the general description, although two
recognized types of illness are caused by two distinct metabolites. The
diarrheal type of illness is caused by a large molecular weight protein,
while the vomiting (emetic) type of illness is believed to be caused by a
low molecular weight, heat-stable peptide.
3. Nature of Disease:
The symptoms of B. cereus diarrheal type food poisoning mimic those of
Clostridium perfringens food poisoning. The onset of watery diarrhea,
abdominal cramps, and pain occurs 6-15 hours after consumption of
contaminated food. Nausea may accompany diarrhea, but vomiting
(emesis) rarely occurs. Symptoms persist for 24 hours in most
instances.
| The United States Food and Drug Administration's Bad Bug Book: Bacillus cereus |