Three people who ate hamburgers in the same restaurant came down with nausea, vomiting and a fever that night. The pathogen most likely responsible for their illness is:

The symptoms of nausea, vomiting, and fever that appeared after consuming hamburgers suggest a case of foodborne illness typically associated with certain pathogens. In this scenario, Salmonella spp. is a common culprit linked to undercooked or contaminated meat, particularly poultry and beef products such as hamburgers. Salmonella infection often manifests with gastrointestinal symptoms including nausea, vomiting, diarrhea, and sometimes fever, which aligns with what the individuals experienced.

While Campylobacter jejuni and Bacillus cereus can also cause foodborne illnesses, they are less likely to be associated with hamburger consumption. Campylobacter typically originates from undercooked poultry and is commonly linked with gastrointestinal issues. Bacillus cereus usually results from improperly stored fried rice or starchy foods rather than meat products.

Listeria monocytogenes, on the other hand, is often associated with ready-to-eat deli meats, unpasteurized dairy products, and certain vegetables rather than hamburgers. It can lead to more severe illnesses, particularly in vulnerable populations, but the immediate symptoms described do not strongly indicate its involvement here.

Therefore, given the context of hamburger consumption and the symptomatology presented, Salmonella spp. is indeed the most likely pathogen responsible for the reported illness.