Session: Poster Session: Streptocci and Enterococci
Monday, October 27, 2008: 12:00 AM
Room: Hall C
Background: Asymptomatic vancomycin-resistant enterococci (VRE) colonization of the gastrointestinal tract typically precedes infection. Colonization may persist for long periods and serve as silent reservoirs for the colonization of other patients. To better understand the epidemiology of colonization of VRE, we compared the molecular characteristics of primary colonization isolates and re-colonization isolates from hospitalized patients. Methods: The study was carried out at a 1,000 bed university hospital with an average of 330,000 patient discharges per year. Our Infection Control Committee policy regarding VRE specifies that patients with three consecutive negative stool cultures obtained at least 1 week apart are considered to have cleared colonization. We performed a 8-year retrospective study of all patients who recurred VRE colonization after they were documented to be clear of VRE. Pulsed field gel electrophoresis and Tn1546 typing were performed. Multi-locus variable number tandem repeat analysis (MLVA) typing was performed. The medical records of all patients were reviewed. Results: Of the 15 patients with recurrent colonization, six continued to be hospitalized in same floor. Five were discharged home and readmitted. Four were moved to another floor. Patients who remained in the same floor had a recurrence of colonization with a strain that was indistinguishable from prior colonizing strain. Patients who moved or were discharged had de novo VRE colonization. Three MLVA types (MTs) were identified among all isolates. MT 159 was the predominant type, accounting for 84.6% (33/39) of the isolates. The remaining types were MT 7 and MT 63, accounted for 5 and one isolate, respectively. All isolates except only one represented MT 159 & MT 7, which belong to the clonal complex17. Conclusions: Patients who moved to another floor or were readmitted had a recurrence of colonization with new strains. In case of these patients, prior colonizing strains were not responsible for recurrent colonization of VRE.