Question

A cook prepares sandwiches for 10 people going for a picnic. Eight out of them develop severe gastroenteritis within 4 to 6 hours of consuming the sandwiches. It is likely that on investigation the cook is found to be a carrier of

• A. Salmonella typhi
• B. Vibrio cholerae
• C. Entamoeba histolytica
• D. Staphylococcus aureus

Hint:

A very short incubation period of a few hours points to a pre-formed toxin, the hallmark of Staphylococcus aureus food poisoning.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The key clue is timing. Symptoms started only 4 to 6 hours after eating the sandwiches, and this points to a food borne illness caused by a toxin that was already present in the food, not by bacteria that first had to multiply inside the body.

Step 2: Key Concept:
Food poisoning has two broad patterns. Toxin mediated food poisoning has a short incubation period of 1 to 6 hours because the pre-formed toxin acts as soon as it is swallowed. Infection type food poisoning has a longer incubation period, usually 12 hours or more, because the organism first needs to multiply or invade the gut lining.

Step 3: Detailed Explanation:
Salmonella typhi causes typhoid fever with an incubation period of 1 to 3 weeks, and even non-typhoidal Salmonella gastroenteritis usually takes 12 to 36 hours to appear, so option (1) is far too slow to match.
Vibrio cholerae causes profuse watery diarrhoea, usually from contaminated water rather than a single cooked food item, with an incubation of several hours to a few days, and it is not the classic cause of a point-source food handler outbreak like this one. This rules out option (2).
Entamoeba histolytica causes amoebic dysentery with an incubation period of days to weeks, far too slow to explain illness within 4 to 6 hours. This rules out option (3).
Staphylococcus aureus is carried on the skin and in the nose of many healthy people, including food handlers. If the cook has a boil or simply carries the organism and handles food like sandwich filling without proper hand hygiene, the bacteria multiply in the food at room temperature and release a heat stable enterotoxin. Eating the toxin, not the live bacteria, causes sudden vomiting and cramping diarrhoea within 1 to 6 hours. This fits the picture exactly.

Step 4: Final Answer:
The short 4 to 6 hour incubation period is the hallmark of toxin mediated Staphylococcus aureus food poisoning.
Hence, the correct answer is option (4).