Foodborne disease — Staphylococcal intoxication: This illness is caused by heat-stable enterotoxin already formed in the food. Which organism is the usual source of that toxin in improperly handled dairy, meats, or bakery items?

Introduction / Context:
Staphylococcal food poisoning is a classic example of a preformed-toxin foodborne illness. The clinical picture (rapid onset nausea, vomiting, abdominal cramps) follows ingestion of heat-stable enterotoxins already present in the food.

Given Data / Assumptions:

• Toxin is formed in the food before eating.
• Heat stability explains illness even if the food was reheated.
• Common vehicles include cream-filled pastries, cooked meats, and dairy left at warm temperatures.

Concept / Approach:
Causative agent: Staphylococcus aureus.Mechanism: production of enterotoxins (SEA, SEB, etc.) in food.Pathophysiology: toxin acts on gut and vagus pathways causing emesis.

Step-by-Step Solution:
Identify which listed organism is known to produce heat-stable enterotoxin in foods.S. aureus is a coagulase-positive staphylococcus commonly carried on skin/nasal mucosa.S. cerevisiae is baker’s yeast and not an enterotoxigenic food pathogen.S. thermophillus is a dairy starter culture organism and non-toxigenic in this context.Therefore, select Staphylococcus aureus.

Verification / Alternative check:
Outbreak investigations repeatedly culture S. aureus from food handlers and foods in temperature danger zones, matching enterotoxin types to cases.

Why Other Options Are Wrong:

• S. cerevisiae: a non-pathogenic yeast used in baking/fermentation.
• S. thermophillus: starter culture, not associated with staphylococcal enterotoxin.
• None of these: incorrect because S. aureus is the known source.

Common Pitfalls:
Confusing toxin-mediated illness (preformed toxin) with infections that require organism growth in the host; assuming reheating always inactivates the toxin (it often does not).

Final Answer:
Staphylococcus aureus