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.