What are the three most common causes of bacterial diarrhea in the United States?

The correct answer identifies the three most common causes of bacterial diarrhea in the United States as Salmonella, Campylobacter, and Shigella. These pathogens are well-documented as significant contributors to gastrointestinal illness, primarily through contaminated food and water sources.

Salmonella is frequently associated with undercooked poultry, eggs, and other meats, while Campylobacter is often linked to raw or undercooked poultry and contaminated water. Shigella typically spreads through person-to-person contact, especially in crowded settings, along with contaminated food and water. The prevalence of these specific bacteria in foodborne illness reports underscores their role as common causes of bacterial diarrhea in the U.S.

Other options listed involve pathogens that are associated with other types of gastrointestinal infections or are less common in the context of bacterial diarrhea specifically. For example, while Escherichia coli can cause gastrointestinal disturbances, not all strains lead to diarrhea and not all are classified as common causes in the United States. Similarly, Clostridium difficile generally causes antibiotic-associated diarrhea rather than typical bacterial diarrhea outbreaks. Other listed organisms, like Vibrio cholerae, primarily cause cholera, which is more geographically specific and not one of the top three causes in the U.S. Giardia lambda, Norovirus