Microbiology · Gram-positive rods
Bacillus cereus !
- Bacterium
- Gram-positive
- For completeness
A spore-forming bacterium that causes food poisoning from reheated rice (fast vomiting) or from other foods (diarrhoea).
Updated 2026-11-01
Also called: fried rice syndrome
At a glance
- Gram
- Gram-positive
- Shape
- Large rods
- Oxygen
- Aerobe or facultative anaerobe
- Family
- Bacillaceae
- Stain
- Gram positive; spore former
Morphology
- Large Gram-positive rods
- Spores that survive cooking
- Motile, unlike B. anthracis
Transmission
- Cooked rice left at room temperature and briefly reheated
- Poorly chilled meat, vegetables and sauces (diarrhoeal form)
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- Cereulide: heat-stable emetic toxin already formed in the food
- Heat-labile enterotoxin made in the gut (diarrhoeal form)
Diseases it causes
- Emetic or diarrhoeal food poisoning Acute (viral) gastroenteritis →
- Endophthalmitis after eye trauma and infections in people who inject drugs
Clinical picture
- Emetic form: nausea and vomiting a few hours after eating
- Diarrhoeal form: watery diarrhoea and cramps later
- Fever is uncommon
Diagnosis
- Clinical and epidemiological diagnosis
- In outbreaks: high counts of the bacterium in the implicated food
Treatment
The food poisoning settles on its own and needs only rehydration. Invasive infections (eye, blood) are treated with antibiotics such as vancomycin, because the bacterium makes beta-lactamases.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Chilling rice and cooked foods promptly
- Not keeping food warm for hours
- Reheating thoroughly
Test yourself
Think of the answer, then tap the question to see it.
Which food is classically linked to the emetic form of B. cereus?
Cooked rice left at room temperature and then fried or reheated.
Why does reheating rice not prevent the emetic form?
Because cereulide is heat-stable and already formed in the food.
Which other food poisoning is confused with the emetic form?
Staphylococcus aureus enterotoxin poisoning, which also causes vomiting within hours.
Related
Related conditions
← Back to the group: Gram-positive rods
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Bacillus cereus Food Poisoning Associated with Fried Rice at Two Child Day Care Centers -- Virginia, 1993 (CDC (MMWR), 1994); Food poisoning: MedlinePlus Medical Encyclopedia (MedlinePlus (NLM), 2024).
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Representative model, for educational purposes only.