Six hours after eating custard left unrefrigerated at a wedding, several guests develop sudden vomiting and cramps without fever or diarrhoea. All recover within 24 hours. The preformed toxin responsible withstands boiling for 30 minutes. Which property of this enterotoxin explains its survival despite reheating the food?

• A It is a heat-labile peptide destroyed above 60 degrees Celsius
• B It is inactivated by gastric acid but protected inside food particles
• C Its activity depends entirely on intact bacterial spores
• D It is remarkably heat-stable, resisting boiling for up to 30 minutes ✓

Explanation

Staphylococcus aureus enterotoxins are preformed, heat-stable superantigens that resist boiling for 30 minutes and even survive canning temperatures, so reheating contaminated food does not prevent illness. Vomiting occurs within 1 to 6 hours due to stimulation of the vagal centre. Heat-labile toxins such as those of Vibrio and ETEC do not fit this short-incubation vomiting illness.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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