Bacillus cereus is a gram-positive, spore-forming,
motile aerobic rod that also grows well anaerobically.1 It
is ubiquitous in the environment, frequently isolated from plants,
meat, eggs, and dairy products.
Food poisoning due to B cereus occurs after eating
food contaminated with spores (diarrheal form) or preformed toxin
(emetic form) as spores are heat resistant, often surviving heating
or cooking.2 Both forms are usually mild and self-limited,
lasting 6 to 24 hours. The diarrhea syndrome includes profuse, watery
diarrhea, abdominal cramps, and vomiting. Nausea, vomiting, and
abdominal cramps within hours of ingesting contaminated foods characterize
the emetic form.
Bacillus cereus is a significant cause of virulent
posttraumatic endophthalmitis, typically following a penetrating
injury or intravenous drug use.3 Severe pain, reduced
visual acuity, chemosis, swelling, and proptosis, often with systemic symptoms,
are noted. Surgical management with parenteral, intraocular, and
topical antimicrobial treatment is indicated. Full vision recovery
Clinically significant B cereus bacteremia is reported
among neonates, intravenous drug users, immunocompromised patients,
and those with indwelling devices.4-9Bacillus
cereus endocarditis is associated with intravenous drug use
or valvular disease.10-12 Pneumonia is reported
in immunosuppressed patients and neonates.13-14 Meningitis
and brain abscess due to B cereus occurred in children
with ventricular shunts or neonates.1,11,15-18 Postsurgical,
traumatic, or burn wounds due to B cereus and severe
deep infections such as necrotizing fasciitis and gangrene have
Bacillus species are commonly considered contaminants.
Among at-risk populations noted above, B cereus should
be considered a potential pathogen.1Bacillus
cereus grows readily on nutrient agar or peptone media
at 25°C to 37°C (77–98.6°F) and may require the addition
of certain amino acids.
Bacillus cereus food poisoning is self-limited, requiring
no antimicrobial therapy. Antibiotic therapy is indicated in invasive B
cereus infections. Empiric therapy with vancomycin or clindamycin,
with or without an aminoglycoside, is most commonly cited in the
literature. Bacillus cereus is resistant to β-lactam
antibiotics but is usually susceptible in vitro to aminoglycosides, chloramphenicol,
ciprofloxacin, clindamycin, erythromycin, imipenem, and vancomycin.5 Surgical
intervention is usually necessary in ophthalmic or skin infections
due to B cereus. Removal of prosthetic devices
is typically necessary for cure.
Food-borne B cereus disease is prevented by appropriate
storage and preparation of food. Bacterial growth may be prevented
if hot food is kept above 60°C (140°F) or rapidly cooled to less
than 10°C (50°F). Careful attention to aseptic technique and handwashing
prevents B cereus infections among immunocompromised patients
and those with indwelling devices.
1. Drobniewski FA. Bacillus cereus
related species. Clin Microbiol Rev
2. Centers for Disease Control and Prevention. Diagnosis and
management of foodborne illness: a primer for physicians and other
health care professionals. MMWR. 2004;53:1.