Vancomycin-resistant enterococci colonizing the intestinal tracts of hospitalized patients

Abstract

A point prevalence culture survey was carried out to investigate the prevalence of fecal carriage of vancomycin-resistant enterococci (VRE) among patients admitted to an 800-bed general hospital where no VRE had been isolated previously. Twenty-two of 636 patients (3.5%) were found to be VRE carriers. Eighteen strains were identified as Enterococcus faecium, three were identified as Enterococcus gallinarum, and one was identified as Enterococcus faecalis. The susceptibilities of the enterococci to ampicillin, vancomycin, and teicoplanin were determined by the disk diffusion and the agar dilution methods. High-level resistance (HLR) to gentamicin and streptomycin was determined by the agar screening method. Eighteen strains (82%) were highly resistant to vancomycin, and four strains (18%) were moderately resistant to vancomycin. Five strains were susceptible to teicoplanin (23%; MICs, < or = 8 micrograms/ml). Only one strain (4.5%, E. faecium) showed HLR to gentamicin, and six strains (27%) showed HLR to streptomycin (one E. faecalis and five E. faecium strains). All 18 E. faecium and 1 E. faecalis strain carried the vanA gene, and 3 E. gallinarum strains carried the vanC gene. An epidemiological investigation revealed several risk factors for VRE colonization: hospitalization and duration of stay in the hematology department and prior vancomycin treatment. The study demonstrates that the patient's gastrointestinal tract is a possible reservoir for VRE, even in hospitals where VRE infections have not yet been observed. Therefore, we conclude that infection control precautions and restriction of glycopeptide usage may be key issues in limiting the emergence and spread of nosocomial VRE infections.