Plasmid DNA and Random Amplified Polymorphic DNA (RAPD) Analyses of Vancomycin-Resistant Enterococcus faecium Isolates

Hong, Won Pyo; Kim, Min; Song, Jeong Won; Kim, Soo Hyun; Shin, Jong Hee; Suh, Soon Pal; Ryang, Dong Wook

Abstract

BACKGROUND: Vancomycin-resistant enterococci (VRE) have been increasingly reported worldwide. The understanding of VRE dissemination in the hospital requires a molecular typing of the strains. VRE appeared recently in Chonnam University Hospital. The purpose of this study is to analyse the strains for their genetic relatedness.
METHODS
Nine vancomycin-resistant E. faecium isolates, collected from six patients during 1995-1996 in Chonnam University Hospital, were typed using plasmid DNA and RAPD analyses. The plasmid DNA of the isolates was obtained by a alkaline lysis method. For RAPD, eight random primers were used. The cluster analysis was performed by NTSYS-pc (numerical taxonomy system and multivariate analysis system, version 1.50, Applied Biostatistics Inc., CA).
RESULTS
Nine VRE isolates were separated into two different molecular types (group A and B) by the plasmid DNA patterns, which were agreed with the RAPD results: the isolates of each group showed the same plasmid DNA patterns and high similarity values in the RAPD analysis. Group A was consisted of two strains isolated from two patients who were admitted at the same room in May 1995. Seven strains of group B were isolated from four patients in the different wards during June 1995 to June 1996.
CONCLUSIONS
Nine VRE isolates from six patients were typed to two groups by plasmid DNA or RAPD analysis. These results suggested the intrahospital spread of two clonal strains of vancomycin-resistant E. faecium.