Which food-borne pathogen would most likely contaminate cooked rice or pasta in open pans at room temperature?

The correct answer is Bacillus cereus, as it is known for its ability to thrive in starchy foods, particularly cooked rice and pasta, when left at room temperature. Bacillus cereus produces heat-stable toxins that can cause foodborne illness, especially when food is not handled properly after cooking. When cooked rice or pasta is left out in an open pan, it creates an environment where this pathogen can multiply, leading to the risk of foodborne illness through the consumption of the contaminated food.

Bacillus cereus can proliferate on starchy dishes because the spores can survive cooking. If the food is not cooled and stored properly, the spores can germinate, leading to toxin production that can cause gastrointestinal symptoms. This makes it crucial to refrigerate cooked foods promptly to minimize any potential risk of contamination.

Other pathogens listed are associated with different foods or conditions. Clostridium perfringens typically contaminates foods that are prepared in large quantities and kept warm for a long time before serving, while Staphylococcus aureus is linked more with foods that are handled by people and can produce toxins if food is left unrefrigerated. Campylobacter jejuni is mostly associated with raw or undercooked poultry and is not typically a concern