Food poisoning with rapid onset of vomiting about 2 hours after eating, with no fever, is most likely due to which organism?

• A. Enterococcus faecium
• B. Bacillus subtilis
• C. Staphylococcus aureus
• D. Listeria monocytogenes

Answer: (C)

Rapid vomiting after a brief incubation points to toxin-mediated food poisoning from a preformed enterotoxin. Staphylococcus aureus makes heat-stable enterotoxins that can contaminate foods and trigger the vomiting center within about 1–6 hours after ingestion. Because the illness is due to toxin effects in the gut rather than bacterial invasion, fever is not a typical feature, and the course is usually short.

Enterococcus faecium is more associated with infections, especially in hospital settings, and not with this rapid, toxin-driven vomiting syndrome. Bacillus subtilis is not a common cause of food poisoning; the vomiting-type illness is classically due to Bacillus cereus, a different species. Listeria monocytogenes tends to cause fever and sometimes invasive disease, with a longer and more variable incubation, particularly dangerous for pregnant women and immunocompromised individuals.