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Cho, Sung, Kwon, Lim, and Koo: Antimicrobial Resistance and Multilocus Sequence Typing of Vancomycin-Resistant Enterococcus faecium Isolated from the Chungcheong Area
Original Article

Korean J Clin Microbiol 2011;14(2):60-66.

Published online: 21 June 2011

DOI: https://doi.org/10.5145/KJCM.2011.14.2.60

Antimicrobial Resistance and Multilocus Sequence Typing of Vancomycin-Resistant Enterococcus faecium Isolated from the Chungcheong Area

Hye Hyun Cho1, Ji Youn Sung2, Kye Chul Kwon1, Jin Sook Lim1, Sun Hoe Koo1

1Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea

2Department of Biomedical Laboratory Science, Far East University, Eumseong, Korea

Correspondence: Sun Hoe Koo, Department of Laboratory Medicine, Chungnam National University Hospital, 640 Daesa-dong, Jung-gu, Daejeon 301-721, Korea. (Tel) 82-42-280-7798, (Fax) 82-42-257-5365, (E-mail) shkoo@cnu.ac.kr

Received 6 September 2010       Revised 29 December 2010       Accepted 29 December 2010

Copyright © 2011 Korean Journal of Clinical Microbiology

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Enterococcus faecium has emerged as an important nosocomial pathogen worldwide, and this trend has been associated with the dissemination of a genetic lineage designated clonal complex 17 (CC17). In the present study, characterization of the glycopeptide resistance mechanism, genetic relatedness, and pathogenicity in isolates of vancomycin-resistant E. faecium in the Chungcheong area were investigated.

Methods

A total of 37 consecutive, non-duplicate, vancomycin-resistant E. faecium were isolated at three university hospitals in the Chungcheong area. The mechanism of glycopeptide resistance and pathogenicity factors were studied using PCR, and the genetic relatedness was determined via multilocus sequence type and esp repeat profile analysis. Additionally, the quinolone resistance-determining regions of parC and gyrA were sequenced to identify mutations involved in ciprofloxacin resistance.

Results

Two genotypes of VRE were confirmed: VanA-phenotype vanA genotype VRE (25 isolates) and VanB-phenotype vanA genotype VRE (12 isolates). MLST analysis revealed five sequence types. A significant result was that ST414 and CNS4 (4-1-1-1-1-1-1) were considered as belonging to CC17. The esp and hyl genes were found in 100% and 86.4% of the isolates, respectively. A total of 37 isolates showed genetic mutations in parC and gyrA.

Conclusion

All isolated strains in the present study belonged to one of the CC17 genotypes including ST414 and CNS4 (4-1-1-1-1-1-1), which were not previously detected in Korea. The combination of MLST and the esp gene repeat profiles can be useful for genetic characterization of VREF isolates with regard to the evolutionary process and epidemiology of the clones.

Keywords: Vancomycin-resistant E. faecium, MLST, Clonal complex 17

REFERENCES

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Table 1.
Ant tibiotic susce eptibility profile s of VREFs
Isolates MIC (μg/mL)
Ampicillin Vancomycin Teicoplanin Ciprofloxacin
CNS3 ＞256 ＞256 16 64
CNS4 ＞256 ＞256 16 64
CNS5 ＞256 ＞256 128 256
CNS6 ＞256 ＞256 32 32
CNS8 256 ＞256 8 64
CNS9 ＞256 ＞256 128 256
CNS10 ＞256 ＞256 256 16
CNS11 ＞256 ＞256 8 32
CNS12 ＞256 ＞256 8 32
CNS13 256 ＞256 256 256
CNS14 256 ＞256 16 256
CNS15 256 ＞256 64 64
CNS16 ＞256 ＞256 64 32
CNS17 ＞256 ＞256 64 256
CNS18 ＞256 ＞256 64 64
CNS19 ＞256 ＞256 64 32
CNS20 ＞256 ＞256 256 64
CNS22 ＞256 ＞256 8 256
CNS23 ＞256 ＞256 128 64
CNS24 ＞256 ＞256 128 256
CNS25 ＞256 ＞256 128 2
CNS27 ＞256 ＞256 128 64
CBS2 ＞256 ＞256 128 128
CBS3 ＞256 ＞256 64 256
CBS6 ＞256 ＞256 128 256
CBS7 ＞256 ＞256 128 64
CBS8 ＞256 ＞256 128 256
CBS9 ＞256 ＞256 16 128
CBS11 ＞256 ＞256 128 256
CBS12 ＞256 ＞256 128 256
CBS14 ＞256 ＞256 64 128
EJS1 ＞256 ＞256 16 128
EJS2 ＞256 ＞256 256 128
EJS3 ＞256 ＞256 8 128
EJS4 ＞256 ＞256 64 128
EJS5 ＞256 ＞256 8 128
EJS7 256 ＞256 16 128

Abbreviations: CNS, isolates from CN hospital; CBS, isolates from CB hospital; EJS, isolates from EJ hospital.

Table 2.
Genotypic characteristics of vancomycin-resistant E. faecium isolates from three Korean hospitals based on multilocus sequence typing, esp repeat profiles and hyl gene
STRAIN ST Allelic profile esp gene repeat profile hyl
atpA ddl gdh purK gyd pstS adk esp-A esp-C
CNS3 78 15 1 1 1 1 1 1 4 8 ＋
CNS4 New 4 1 1 1 1 1 1 4 8 ＋
CNS5 192 15 1 1 1 1 7 1 4 8 ＋
CNS6 78 15 1 1 1 1 1 1 5 6 ＋
CNS8 192 15 1 1 1 1 7 1 5 6 ＋
CNS9 78 15 1 1 1 1 1 1 4 8 ＋
CNS10 78 15 1 1 1 1 1 1 5 6 ＋
CNS11 192 15 1 1 1 1 7 1 5 6 ＋
CNS12 192 15 1 1 1 1 7 1 4 8 ＋
CNS13 78 15 1 1 1 1 1 1 5 6 ＋
CNS14 192 15 1 1 1 1 7 1 4 8 ＋
CNS15 192 15 1 1 1 1 7 1 5 6 ＋
CNS16 192 15 1 1 1 1 7 1 4 8 −
CNS17 78 15 1 1 1 1 1 1 4 8 ＋
CNS18 192 15 1 1 1 1 7 1 5 6 ＋
CNS19 192 15 1 1 1 1 7 1 5 6 ＋
CNS20 78 15 1 1 1 1 1 1 5 6 ＋
CNS22 192 15 1 1 1 1 7 1 4 8 ＋
CNS23 192 15 1 1 1 1 7 1 5 6 ＋
CNS24 192 15 1 1 1 1 7 1 4 8 ＋
CNS25 192 15 1 1 1 1 7 1 4 8 ＋
CNS27 17 1 1 1 1 1 1 1 4 8 ＋
CBS2 17 1 1 1 1 1 1 1 4 8 ＋
CBS3 78 15 1 1 1 1 1 1 5 6 −
CBS6 78 15 1 1 1 1 1 1 4 8 −
CBS7 192 15 1 1 1 1 7 1 5 6 ＋
CBS8 192 15 1 1 1 1 7 1 4 8 ＋
CBS9 414 15 5 1 1 1 20 1 4 8 −
CBS11 192 15 1 1 1 1 7 1 4 8 ＋
CBS12 192 15 1 1 1 1 7 1 4 8 ＋
CBS14 78 15 1 1 1 1 1 1 5 6 ＋
EJS1 192 15 1 1 1 1 7 1 5 6 ＋
EJS2 192 15 1 1 1 1 7 1 5 6 ＋
EJS3 78 15 1 1 1 1 1 1 6 7 ＋
EJS4 78 15 1 1 1 1 1 1 4 8 −
EJS5 192 15 1 1 1 1 7 1 5 6 ＋
EJS7 17 1 1 1 1 1 1 1 4 8 ＋

Abbreviations: CNS, isolates from CN hospital; CBS, isolates from CB hospital; EJS, isolates from EJ hospital.

Table 3.
parC and gyrA mutation in 37 E. faecium isolates corresponding to ciprofloxacin MIC
Amino acid mutation in gene No. of isolates with ciprofloxacin MIC (μg/mL) Total no. of islates
parC (80) gyrA (83) 2 4 8 16 32 64 128 256 37
R R       1 3 6 4 3 17
R I         2 2 1 4 9
I R             1 1 2
I I 1         1 3 4 9

Abbreviations: R, arginine; I, isoleucine.

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