3.08 Bacillus Species
Microbiology review for the USMLE Step 1 exam
- Bacillus species are aerobic, sporulating, gram + rod-shaped bacteria found in nature such as soil, water, and air
- Two main species to discuss: Bacillus cereus and Bacillus anthracis
- Bacillus cereus is associated with foodborne infections and specifically with reheated rice, as spores can survive cooking and continue to grow in refrigerated rice, leading to enteritis symptoms
- Bacillus anthracis causes anthrax, most commonly contracted through contact with infected animals, particularly grazing animals such as sheep, goats, and cattle.
- There are three forms of anthrax: cutaneous anthrax, inhalation anthrax, and gastrointestinal anthrax
- Cutaneous anthrax is the most common form and results from inoculation of spores through a cut or opening in the skin
- Inhalation anthrax occurs when spores are inhaled and leads to systemic illness, mediastinal widening, septic shock, and death
- Gastrointestinal anthrax results from ingesting spores in contaminated food and leads to severe abdominal symptoms.
