How does Bacillus cereus cause disease?

• A. Invades tissues and causes disease
• B. Produces toxin
• C. Requires host cell invasion to cause disease
• D. Does not produce toxins

Answer: (C)

Bacillus cereus causes disease mainly through toxin production, not by invading tissues. When contaminated food is eaten, preformed toxins in the food or toxins produced in the gut trigger symptoms. There are two major toxin-related syndromes: the emetic form, caused by the stable cereulide toxin leading to vomiting, and the diarrheal form, caused by heat-labile enterotoxins that cause diarrhea. Even without the bacteria invading the intestinal lining, these toxins can generate illness, and the disease is typically self-limited. So the disease mechanism is toxin-mediated, not tissue invasion.