Update on the changing epidemiology of Clostridium difficile-associated disease

From being considered mainly as a nosocomial disease associated with the use of broad spectrum antibiotics, the epidemiology of Clostridium difficile -associated disease (CDAD) seems to be changing. In this Review, the author focuses on outbreaks of CDAD that have been associated with higher mortality rates and reduced effectiveness of treatment with metronidazole. The emergence of a fluoroquinolone-resistant strain of C. difficile (BI/NAP1/027), new at-risk populations and the increased incidence of CDAD are also discussed. In the past, Clostridium difficile -associated disease (CDAD) was thought of mainly as a nosocomial disease associated with the use of broad-spectrum antibiotics, but its epidemiology seems to be changing. Since 2002, outbreaks of severe CDAD associated with increased mortality and reduced effectiveness of treatment with metronidazole have focused attention on this challenging pathogen. A fluoroquinolone-resistant strain of C. difficile (BI/NAP1/027) has been predominantly associated with these outbreaks. Changes in the epidemiology of CDAD include the emergence of new at-risk populations and the increased incidence of the disease. Infection control programs and more effective treatments offer hope that future outbreaks of CDAD can be controlled. Key Points The incidence of health-care-associated C. difficile -associated disease (CDAD) is rising Recent outbreaks of CDAD have been characterized by severe disease and increased mortality Atypical hypervirulent BI/NAP1/027 is resistant to fluoroquinolones, produces more toxin and carries the gene encoding binary toxin CDAD might be underdiagnosed if only one stool toxin assay is performed or if atypical at-risk patients are not assayed Control of health-care-associated CDAD can involve a range of strategies Vancomycin and metronidazole remain the mainstays of treatment for CDAD, but newer investigational therapies hold promise