Molecular Characterization of Vancomycin-Resistant Enterococcus faecium Isolates from Korea

Abstract

A total of 98 vancomycin-resistant Enterococcus faecium (VREF) isolates from four tertiary-care hospitals in Korea during the period between 1998 and 2004 were analyzed for genotypic characteristics using the multiplex PCR, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and esp gene analysis. Ninety-two isolates of VREF with VanA phenotype and five of six isolates with VanB phenotype possessed the vanA gene. MLST analysis revealed 9 sequence types (STs), which belonged to a single clonal complex (CC78, clonal lineage C1). Five strains showing incongruence between phenotype and genotype (VanB-vanA) did not belong to the same genotypic clone. The esp gene was detected in all VREF strains, showing 12 different esp repeat profiles. Data suggest that an epidemic clonal group of VREF, CC78 with esp gene, is also present in Asia and has differentiated into multiple diverse genotypic clones during the evolutionary process.Since the first isolation of vancomycin-resistant Enterococcus faecalis and Enterococcus faecium in 1988 (17), vancomycinresistant enterococci (VRE) have become one of the major threats to public health in many parts of the world. Although E. faecalis is more common in human infections, vancomycin resistance is more frequently observed in E. faecium isolates. Most vancomycin-resistant E. faecium (VREF) strains isolated in Korea showed the VanA phenotype, which is defined as having high-level resistance to vancomycin and teicoplanin (2). VREF isolates with the VanB phenotype characterized by variable levels of resistance to vancomycin but by susceptibility to teicoplanin have been reported in Korea since 1997 (12). Generally, the vanA gene cluster confers the VanA phenotype and vanB gene cluster is associated with the VanB phenotype. Recently, however, VRE strains with the vanA gene and VanB phenotype have been found in Japan, Taiwan, and Korea (3,6,8,11).VREF is an important concern not only because VREF infection is difficult to treat in clinical practice but also because VREF clones can spread within hospitals as well as between regions or countries. Molecular epidemiologic studies could clarify the genetic relatedness and molecular evolution of VREF clones. In the current study, we have investigated the phenotypic and genotypic characteristics of VREF isolates from four tertiary-care hospitals in Korea by using the broth microdilution test, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and analysis of the esp repeat profile. MATERIALS AND METHODS VREF isolates.A total of 98 vancomycin-resistant E. faecium (VREF) isolates from four tertiary-care hospitals in Korea (Samsung Medical Center, Severans Hospital, Kyunghee University Hospital, and Kyungbuk National University Hospital) were analyzed in this study. The most common specimen source was urine (25 isolates) followed by rectal swab (14 isolates), blood (13 isolates), pus (9 isolates), wound (5 isolates), fluid (5 isolates), sputum (2 isolates), and tissue (2 isolates). Duplicate strains f...

Current Trends of Emergence and Spread of Vancomycin-Resistant Enterococci

“…Several studies performed during outbreaks in Taiwanese hospitals revealed a preferred prevalence of (hospital-associated) vanA-type vancomycinresistant E. faecium strains (Hsieh et al, 2009;Hsieh et al, 2010). In South-Korean hospitals (and outside hospitals) vanA-genotype (VanB phenotype) E. faecium were widely prevalent (Ko et al, 2005;Shin et al, 2006;Park et al, 2008). Recent reports from China revealed also a preferred prevalence of vanA-type vancomycin resistance among clinical VRE (Zheng et al, 2007a;Zheng et al, 2007b;Zhu et al, 2009).…”

Antimicrobial Resistance and Multilocus Sequence Typing of Vancomycin-ResistantEnterococcus faeciumIsolated from the Chungcheong Area

“…The presence of the esp and hyl gene in isolates was determined by PCR using primers; esp-F (5'-GGTCACAAAGC-CCAACTTGT-3') and esp-R (5'-ACGTCGAAAGTTCGATT-TCC-3') [6] and hyl-F (5'-ACAGAAGAGCTGCAGGAAATG-3') and hyl-R (5'-GACTGACGTCCAAGTTTCCAA-3') [11]. To determine repeat number variations of esp A and C repeats, two different primer combinations were used; espfs7F (5'-CGACCGATTTAGCAGTAAC-3') -espfm5R (5'-CAGCTGC-GCTAACATCTAC-3') and espfm5F (5'-AAAGAAGATTTA-CCAAAAGATACTAAG-3') -espfs3R (5'-TTCGGCGCTTTT-TATC-3') respectively [12].…”

“…The characteristics of CC17 are its resistance to ampicillin and quinolone, and variant esp gene as E. faecium pathogenicity island (PAI) [4,5]. It has been reported that the organisms isolated in Korea belong to CC17 [6,7]. Thus study on epidemiology and genetic characteristics of CC17 is needed.…”

Antibiotics Resistance and Molecular Analysis of Enterococcus Isolated from the Han-river in Korea

“…우리나라에서 분리된 VREF의 대부분은 IS1542와 IS1216V가 삽입되어 있어 유럽에 서 분리된 균주와 매우 유사하며 (Woodford et al, 1998;da Costa Darini et al, 1999) VRE 분리균주 6주에서 7개의 housekeeping 유전자의 염기 서열로 http://efaecium.mlst.net에서 ST를 확인하였을 때 분리균주 Km37, Km39 및 Km40은 ST78로, 분리균주 Km20, Km36 및 Km38은 각각 ST18, ST230 및 ST192로 나타났다 (Table 4). ST18, ST78 및 ST192는 국내 병원에서 분리된 바 있으며, 특히 ST78은 국내에서 가장 흔하게 분리되는 ST이다 (Ko et al, 2005;Lee et al, 2006). ST230은 대한민국 전북의 한 병원에서 분리되 어 MLST database에 등록되어 있다(MLST database ID : 587).…”

“…본 연구에서 확인된 ST를 대상으로 eBURST program을 통 해 MLST database의 410개의 ST와 비교하여 clonal complex (CC)를 확인한 결과를 (Willems et al, 2005;Top et al, 2008), 국내 병원에서 분리되고 있는 대부분의 균주 역시 CC 17에 속한다 (Ko et al, 2005;Lee et al, 2006;Lopez et al, 2009). …”