Currently, no single U.S. surveillance system can provide estimates of the burden of all types of health care–associated infections across acute care patient populations. We conducted a prevalence survey in 10 geographically diverse states to determine the prevalence of health care–associated infections in acute care hospitals and generate updated estimates of the national burden of such infections.

We defined health care–associated infections with the use of National Healthcare Safety Network criteria. One-day surveys of randomly selected inpatients were performed in participating hospitals. Hospital personnel collected demographic and limited clinical data. Trained data collectors reviewed medical records retrospectively to identify health care–associated infections active at the time of the survey. Survey data and 2010 Nationwide Inpatient Sample data, stratified according to patient age and length of hospital stay, were used to estimate the total numbers of health care–associated infections and of inpatients with such infections in U.S. acute care hospitals in 2011.

Surveys were conducted in 183 hospitals. Of 11,282 patients, 452 had 1 or more health care–associated infections (4.0%; 95% confidence interval, 3.7 to 4.4). Of 504 such infections, the most common types were pneumonia (21.8%), surgical-site infections (21.8%), and gastrointestinal infections (17.1%). Clostridium difficile was the most commonly reported pathogen (causing 12.1% of health care–associated infections). Device-associated infections (i.e., central-catheter–associated bloodstream infection, catheter-associated urinary tract infection, and ventilator-associated pneumonia), which have traditionally been the focus of programs to prevent health care–associated infections, accounted for 25.6% of such infections. We estimated that there were 648,000 patients with 721,800 health care–associated infections in U.S. acute care hospitals in 2011.

Results of this multistate prevalence survey of health care–associated infections indicate that public health surveillance and prevention activities should continue to address C. difficile infections. As device- and procedure-associated infections decrease, consideration should be given to expanding surveillance and prevention activities to include other health care–associated infections.