A hospital outbreak of diarrhea due to an emerging epidemic strain of Clostridium difficile.

Background: Increased Clostridium difficile-associated disease (CDAD) in a hospital and an affiliated long-term care facility continued despite infection control measures. We investigated this outbreak to determine risk factors and transmission settings.

Methods: The CDAD cases were compared according to where the disease was likely acquired based on health care exposure and characterization of isolates from case patients, asymptomatic carriers, and the environment.