The effect of vancomycin and third-generation cephalosporins on prevalenceof vancomycin-resistant enterococci in 126 US adult intensive care units

Background: Patient-specific risk factors for acquisition of vancomycin-res istant enterococci (VRE) among hospitalized patients are becoming well defi ned. However, few studies have reported data on the institutional risk fact ors, including rates of antimicrobial use, that predict rates of VRE. Ident ifying modifiable institutional factors can advance quality-improvement eff orts to minimize hospital-acquired infections with VRE. Objective: To determine the independent importance of any association betwe en antimicrobial use and risk factors for nosocomial infection on rates of VRE in intensive care units (ICUs). Design: Prospective ecologic study. Setting: 126 adult ICUs from 60 U.S. hospitals from January 1996 through Ju ly 1999. Patients: All patients admitted to participating ICUs. Measurements: Monthly use of antimicrobial agents (defined daily doses per 1000 patient-days), nosocomial infection rates, and susceptibilities of all tested enterococci isolated from clinical cultures. Results: Prevalence of VRE (median, 10%; range, 0% to 59%) varied by type o f ICU and by teaching status and size of the hospital. Prevalence of VRE wa s strongly associated with VRE prevalence among inpatient non-ICU areas and outpatient areas in the hospital, ventilator-days per 1000 patient-days, a nd rate of parenteral vancomycin use. In a weighted linear regression model controlling for type of ICU and rates of VRE among non-ICU inpatient areas rates of vancomycin use (P < 0.001) and third-generation cephalosporin use (P = 0.02) were independently associated with VRE prevalence. Conclusions: Higher rates of vancomycin or third-generation cephalosporin u se were associated with increased prevalence of VRE, independent of other I CU characteristics and the endemic VRE prevalence elsewhere in the hospital . Decreasing the use rates of these antimicrobial agents could reduce rates of VRE in ICUs.