USMLE Step 2 CK High-Yield Practice Test

The most common cause of diarrhea in healthcare settings is Clostridium difficile. C. difficile infections typically occur in patients who have recently received antibiotics, which disrupt the normal gut flora and allow for the overgrowth of this bacterium. This leads to a spectrum of disease, from mild diarrhea to fulminant colitis. In healthcare environments, the risk increases due to the use of broad-spectrum antibiotics and the sharing of medical facilities among patients with various health issues, making it a significant concern for infection control.

Norovirus is indeed a common cause of gastroenteritis outbreaks, especially in closed environments like hospitals and nursing homes; however, it is more associated with community settings than with chronic healthcare-associated infections. Rotavirus is primarily a concern in pediatric populations and has been largely mitigated in children due to vaccination, while Salmonella is more often linked to foodborne outbreaks rather than nosocomial infections in healthcare facilities. Thus, Clostridium difficile stands out as the primary pathogen in the context of healthcare-associated diarrhea.