An estimated 453,000 C. difficile cases occurred in 2011, or about 147 per 100,000 people, according to a study reported today in the New England Journal of Medicine. While about two-thirds of the cases were healthcare-associated, only 24% emerged while the patient was hospitalized. “According to our estimates, nearly 345,400 cases occurred outside of hospitals, indicating that the prevention of C. difficile infection should go beyond hospital settings,” the authors said. The 30-day mortality rate for healthcare-associated cases was about 9%. The estimates are based on data from the Centers for Disease Control and Prevention’s Emerging Infections Program, which includes surveillance areas in 10 states. About half of the cases were detected using nucleic acid amplification tests, which may represent colonization rather than true infection, the authors note.