Vancomycin-resistant Enterococci: Incidence, Antimicrobial Susceptibility, and Resistance Genotypes

Lee, Wee Gyo; Jung, Min Kwon; Kwak, Yun Sik

Abstract

BACKGROUND: Infections caused by vancomycin-resistant enterococci (VRE) are becoming increasingly prevalent throughout the world. VRE can spread by direct patient-to-patient contact as well as on the hands of personnel and contaminated environmental surfaces. The purpose of this study was to examine the incidence of VRE among total enterococci from clinical specimen and investigate the antimicrobial characteristics and resistance genotypes of isolated VRE.
METHODS
A total of 790 enterococcal isolates from patients over a period of 12 months were screened for vancomycin resistance using brain heart infusion agar plates supplemented with 6 g/mL of vancomycin. The incidence of VRE among enterococcal isolates was calculated from microbiology statistics program. Twenty three isolates of VRE were tested for minimal inhibitory concentrations (MIC) of vancomycin, penicillin, and gentamicin and resistance genotypes.
RESULTS
In the first half period, the incidence of VRE was 1.9%, and in the second half, the incidence increased to 7.7%. Thirteen strains were found to be highly resistant to vancomycin, penicillin and gentamicin (MIC, >128 g/mL). According to the direct PCR analyses, the frequency of vanB, vanC1, and vanC2 types was 13, 7, and 3 strains, respectively.
CONCLUSIONS
Continued vigilance, strict enforcement of infection control, and curtailment of vancomycin use seem to be our best approaches to controlling this increasingly important problem. For this purposes, accurate and timely detection of vancomycin-resistance and periodic investigation for incidence are essential.