Which is the cause of food poisoning with rapid onset after eating due to enterotoxin production?

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

Answer: (C)

Rapid onset of food poisoning is typically due to ingestion of preformed toxins in the food. Staphylococcus aureus makes potent enterotoxins that are heat-stable and can accumulate in foods that are left at room temperature or handled by people. When these toxins are eaten, they trigger rapid symptoms—nausea and vomiting often within a few hours, sometimes with abdominal cramps and diarrhea. Because the toxin is already present, the illness can occur even if the food is later cooked or reheated, and the bacteria themselves may be gone or inactive by then. This pattern—the quick onset after a meal and the toxin-mediated mechanism—points to Staphylococcus aureus as the cause.

Enterococcus faecium is mainly linked to hospital-associated infections and does not cause rapid toxin-mediated food poisoning. Bacillus subtilis is not a typical culprit for this kind of toxin-mediated illness (the well-known Bacillus cereus can cause it, but that’s a different organism). Listeria monocytogenes causes listeriosis with longer incubation and systemic illness, not rapid vomiting after a single meal.