Epidemiology of Clostridium difficile infection.

There has been dramatic change in the epidemiology of Clostridium difficile infection (CDI) since the turn of the 21st century noted by a marked increase in incidence and severity, occurring at a disproportionately higher frequency in older patients. Historically considered a nosocomial infection associated with antibiotic exposure, CDI has now also emerged in the community in populations previously considered low risk. Emerging risk factors and disease recurrence represent continued challenges in the management of CDI. The increased incidence and severity associated with CDI has coincided with the emergence and rapid spread of a previously rare strain, ribotype 027. Recent data from the United States and Europe suggest that the incidence of CDI may have reached a crescendo in the recent years and is perhaps beginning to plateau. The acute care direct costs of CDI were estimated to be US$4.8 billion in 2008. However, nearly all the published studies have focused on CDI diagnosed and treated in the acute care hospital setting and fail to measure the burden outside the hospital, including recently discharged patients, outpatients, and those in long-term care facilities. Enhanced surveillance methods are needed to monitor the incidence, to identify populations at risk, and to characterize the molecular epidemiology of strains causing CDI.