Epidemiology of vancomycin-resistant enterococci among patients on an adult stem cell transplant unit: observations from an active surveillance program.

OBJECTIVE: To use the findings of an active surveillance program to delineate the unique epidemiology of vancomycin-resistant enterococci (VRE) in a mixed population of transplant and nontransplant patients hospitalized on a single patient care unit.
DESIGN: Surveillance survey and case-control analysis.
SETTING: A 19-bed adult bone marrow and stem cell transplant unit at a referral and primary-care center. PATIENTS: The study included patients undergoing transplantation, patients who had previously received bone marrow or stem cell transplants, and patients with other malignancies and hematological disorders who were admitted to the study unit.
METHODS: Patients not previously identified as colonized with VRE had perirectal swab specimens collected at admission and once weekly while hospitalized on the unit. The prevalence of VRE colonization at admission and the incidence throughout the hospital stay, genotypes of VRE specimens as determined by pulsed field gel electrophoresis, and risk factors related to colonization were analyzed.
RESULTS: There was no significant difference in the prevalence or incidence of new colonization between nontransplant patients and prior or current transplant recipients, although overall prevalence at admission was significantly higher in the prior transplant group. Preliminary genotypic analysis of VRE isolates from transplant patients suggests that a proportion of cases of newly detected VRE carriage may represent prior colonization not detected at admission, with different risk factors suggestive of a potential epidemiological distinction.
CONCLUSION: Examination of epidemiological and microbiological data collected by an active surveillance program provides useful information about the epidemiology of VRE that can be applied to inform rational infection control strategies.