Vancomycin-resistant enterococci in intensive-care hospital settings: transmission dynamics, persistence, and the impact of infection control programs

Vancomycin-resistant enterococci (VRE) have recently emerged as a nosocomial pathogen and present an increasing threat to the treatment of severely ill patients in intensive-care hospital settings. We out-line results of a study of the epidemiology of VRE transmission in ICUs and define a reproductive number R0; the number of secondary colonization cases induced by a single VRE-colonized patient in a VRE-free ICU, for VRE transmission. For VRE to become endemic requires R0>1. We estimate that in the absence of infection control measures R0 lies in the range 3-4 in defined ICU settings. Once infection control measures are included R0=0.6, suggesting that admission of VRE-colonized patients can stabi-lize endemic VRE. Key words: vancomycin resistance- transmission dynamics- epidemiology- infection control Increasing antibiotic resistance in common bac-terial pathogens presents a growing threat world-wide. The emergence of vancomycin-resistant en-terococci (VRE) as a nosocomial pathogen is a strik-ing example of this new danger to vulnerable pa-tients. In both the United States and the Unite