Authors: Fernanda C. Lessa, Yi Mu, Wendy M. Bamberg, Zintars G. Beldavs, Ghinwa K. Dumyati, John R. Dunn, Monica M. Farley, Stacy M. Holzbauer, James I. Meek, Erin C. Phipps, Lucy E. Wilson, Lisa G. Winston, Jessica A. Cohen, Brandi M. Limbago, Scott K. Fridkin, Dale N. Gerding, and L. Clifford McDonald

Summary

In this study, performed in 2011, the authors conduct an active population- and laboratory-based surveillance across 10 geographic areas in the United States to identify cases of C. difficile  infection (stool specimens positive for C. difficile  on either toxin or molecular assay in residents ≥1 year of age). Cases were classified as community-associated or health care–associated. In a sample of cases of C. difficile  infection, specimens were cultured and isolates underwent molecular typing. Regression models were used to calculate estimates of national incidence and total number of infections, first recurrences, and deaths within 30 days after the diagnosis of C. difficile  infection.

A total of 15,461 cases of C. difficile  infection were identified in the 10 geographic areas; 65.8% were health care–associated, but only 24.2% had onset during hospitalization. After adjustment for predictors of disease incidence, the estimated number of incident C. difficile infections in the United States was 453,000 (95% confidence interval [CI], 397,100 to 508,500). The incidence was estimated to be higher among females (rate ratio, 1.26; 95% CI, 1.25 to 1.27), whites (rate ratio, 1.72; 95% CI, 1.56 to 2.0), and persons 65 years of age or older (rate ratio, 8.65; 95% CI, 8.16 to 9.31). The estimated number of first recurrences of C. difficile  infection was 83,000 (95% CI, 57,000 to 108,900), and the estimated number of deaths was 29,300 (95% CI, 16,500 to 42,100). The North American pulsed-field gel electrophoresis type 1 (NAP1) strain was more prevalent among health care–associated infections than among community-associated infections (30.7% vs. 18.8%, P<0.001).

C. difficile caused approximately 453,000 incident infections and was associated with approximately 29,000 deaths in the United States in 2011. Persons 65 years of age or older, whites, and females had higher incidences than their comparators. This national estimate of C. difficile infection is higher than previous U.S. estimates (240,000 to 333,000) that relied on passive surveillance, data from health care facilities in a single state, administrative data, or data from managed-care populations in a specific region. However, comparisons with previous estimates are limited by differences in definitions of C. difficile infection and in analytical methods.

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