Study on the Infection Due to VanA Type Vancomycin-resistant Enterococci

Cheong, Hee Jin; Kim, Woo Joo; Woo, Heung Jeong; Kim, Min Ja; Park, Seung Chul

Abstract

BACKGROUND
Vancomcyin-resistant enterococci(VRE) have become one of major nosocomial pathogens in USA and Europe since 1986. In Korea, only a few cases of VRE infection were reported until now. We investigated the rate of vancomycin resistance among clinical enterococcal isolates, characterized the genotypes of VRE isolates by using polymerase chain reaction (PCR), and analyzed the molecular relatedness of those isolates by using pulsed field gel electrophoresis(PFGE) technique.
METHODS
Standard disk diffusion test, break point screening test and measurement of minimal inhibitory concentraion(MIC) were used for identification of VRE. Duplex vanA-vanB PCR for genotyping of vancomcyin resistance, and PFGE for molecular epidemiologic analysis were performed.
RESULTS
Incidence of VRE among clinical enterococcal isolates during the study period(July, 1995~June,1996) was 1.0%(2/202). Two strains among 68 suspicious VRE, which were identified by disk diffusion method, were confirmed as true VRE by break point screening and MIC test. MIC of both VRE isolates were same(vancomycin : 512microgram/ml, teicoplanin 64microgram/ ml). Both VRE isolates were confirmed as vanA genotypes by duplex PCR and identical clones by PFGE and dendrogram analysis.
CONCLUSION
Frequency of VRE among clinical enterococcal isolates is still very low(1%) in this hospital. We reported two VRE isolates which were confirmed by MIC determination and PCR genotyping. Judicious surveillance study of VRE and strict control of vancomycin usage are required to prevent the emergence and dissemination of VRE.