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 outline 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 stabilize endemic VRE.
vancomycin resistance; transmission dynamics; epidemiology; infection control