Background:Nosocomial infections caused by vancomycin-resistant enterococci (VRE) are increasing problem in Korea. Until now, no nationwide study has been performed. The aim of the present study was to monitor the antimicrobial resistance of vancomycin-resistant Enterococcus faecium (VREF).

Methods: Two hundred and two E. faecium isolated in 10 teaching hospital were studied. To detect VRE, the brain heart infusion agar containing 6 μg /mL vancomycin was used as the screening agar. The MIC was determined using agar dilution test. The vancomycin resistance genes (vanA, vanB & vanD)and genes (aac(6’)Ie-aph(2”) Ia & ant(6’) Ia encoding the aminoglycoside-modifying enzymes were detected by multiplex PCR using specific primers. 

Results:Thirty-nine VREF were detected from 202 isolates. All had vancomycin MICs ≥256 μg /mL and harboured vanA gene. No isolates revealed positive results for the vanB or vanD gene. However, the MIC range for teicoplanin was 2 to ≥256 μg/mL. All isolates with gentamicin MIC ≥ 500 μg/mL gave positive results for the aac(6’) Ieaph(2”) Ia genes and with streptomycin ≥2000 μg /mL gave positive results for the ant(6’)Ia gene. 

Conclusions:All VREF harboured vanA gene. According to MIC tests, 7 isolates(18%) showed intermediate or susceptible to teicoplanin. Therefore we need a study concerning the clinical meaning. The VREF in Korea contain at least one of genes encoding the aminoglycoside-modifying enzymes. This means there are only limited numbers of antibiotics to choose. (Korean J Clin Microbiol 2003;6(1):18-22)