Bacillus Cereus Food Poisoning

Bacillus cereus food poisoning is caused by spore forming Gram-positive bacilli that produce either a preformed emetic toxin (cereulide) or enterotoxins in the gut.

• Emetic syndrome follows cooked rice, pasta and starchy foods left at room temperature then reheated (spores survive cooking, germinate and make toxin); onset 30 minutes to 6 hours.
• Diarrhoeal syndrome follows meat, vegetables, sauces, soups and dairy; enterotoxins form in the small bowel, onset 6 to 15 hours.
• Cereulide is heat and acid stable, so reheating does not destroy it.

Emetic type: abrupt nausea and vomiting with cramps, resembling staphylococcal poisoning, lasting 6 to 24 hours.

• Diarrhoeal type: watery diarrhoea with abdominal pain and tenesmus, vomiting uncommon, resolving in 12 to 24 hours.
• Fever is absent or mild.
• Differential diagnosis: Staphylococcal toxin poisoning, Clostridium perfringens, norovirus, chemical poisoning, Vibrio infections, Salmonella.
• Complications: dehydration; rarely fulminant hepatic failure, rhabdomyolysis or death after emetic toxin; bacteraemia, endophthalmitis, central line infection and pneumonia in immunosuppressed hosts and intravenous drug users.

Clinical, supported by incubation time, food history and clusters.

• Culture of food (more than 10^5 organisms per gram) and stool or vomit; isolation from stool alone is not diagnostic since it may colonise.
• Electrolytes, creatinine, liver enzymes, lactate and creatine kinase in severe emetic cases.
• Blood cultures if febrile or immunosuppressed (distinguish from contaminants).

Supportive

• Oral rehydration, intravenous Ringer lactate for dehydration (adults 1 to 2 L over 1 hour then guided by response; children 20 mL/kg boluses), electrolyte replacement.
• Most cases resolve without specific therapy within 24 hours.

Pharmacological

• Antiemetics: ondansetron 4 to 8 mg oral or IV (children 0.15 mg/kg).
• Antibiotics are not indicated for food poisoning.
• Invasive infection (bacteraemia, endophthalmitis, device infection): vancomycin 15 to 20 mg/kg IV every 8 to 12 hours (trough guided) or clindamycin 600 mg IV every 8 hours, with or without ciprofloxacin 400 mg IV twice daily or meropenem 1 g IV every 8 hours; remove infected lines; intravitreal antibiotics for endophthalmitis.
• Fulminant hepatic failure: supportive intensive care, N-acetylcysteine (150 mg/kg over 1 hour, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours), and transplant referral.

Public health: cool rice rapidly (within 1 hour) and refrigerate at 5 C or less, reheat to above 74 C, discard rice stored at room temperature more than 4 hours.

Special groups: neonates and immunosuppressed patients (invasive disease), pregnancy (supportive care).

Red flags: jaundice or coagulopathy after emetic illness, persistent bacteraemia, visual symptoms.

Follow-up: none after uncomplicated illness; review liver tests if jaundice develops.