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Open Access Highly Accessed Research article

Identification of vancomycin-resistant enterococci clones and inter-hospital spread during an outbreak in Taiwan

Sai-Cheong Lee1*, Mi-Si Wu2, Hsiang-Ju Shih1, Shu-Huan Huang3, Meng-Jiun Chiou4, Lai-Chu See45 and Liang-Kee Siu6

Author affiliations

1 Division of Infectious Diseases, Chang Gung Memorial Hospital, Keelung, Chang Gung University, 222, Mai Chin Road, Kwei-Shan, Tao-Yuan, Taiwan

2 Department of Nephrology, Chang Gung Memorial Hospital, Keelung, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan

3 Department of Laboratory Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan

4 Department of Public Health, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan

5 Biostatistics Core laboratory, Molecular Medicine Research Center, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan

6 Division of Clinical Research, National Health Research Institute, Miaoli, Taiwan

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Citation and License

BMC Infectious Diseases 2013, 13:163  doi:10.1186/1471-2334-13-163

Published: 4 April 2013

Abstract

Background

In 2003, nosocomial infections caused by vancomycin-resistant enterococci (VRE) occurred rarely in Taiwan. Between 2003 and 2010, however, the average prevalence of vancomycin resistance among enterococci spp. increased from 2% to 16% in community hospitals and from 3% to 21% in medical centers of Taiwan. We used molecular methods to investigate the epidemiology of VRE in a tertiary teaching hospital in Taiwan.

Methods

Between February 2009 and February 2011, rectal samples and infection site specimens were collected from all inpatients in the nephrology ward after patient consent was obtained. VRE strain types were determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

Results

A total of 59 vanA gene-containing VRE isolates (1 per patient) were obtained; 24 originated from rectal sample surveillance of patients who exhibited no symptoms (22 Enterococcus faecium and 2 Enterococcus faecalis), and 35 had developed infections over 3 days after admission (32 E. faecium, 2 E. faecalis, and 1 Enterococcus durans). The 59 VRE isolates demonstrated vancomycin minimum inhibitory concentrations (MICs) of ≥256 μg/m. The MIC range for linezolid, tigecycline, and daptomycin was 0.25–1.5 μg/mL, 0.032–0.25 and 1–4 μg/mL, respectively. For 56 isolates, the MIC for teicoplanin was >8 μg/mL. The predominant types in the nephrology ward were MLST types 414, 78, and18 as well as PFGE types A, C, and D.

Conclusion

VREs are endemic in nephrology wards. MLST 414 is the most predominant strain. The increase VRE prevalence is due to cross-transmission of VRE clones ST 414,78,18 by undetected VRE carriers. Because similar VRE STs had been reported in a different hospital of Taiwan, this finding may indicate inter-hospital VRE spread in Taiwan. Active surveillance and effective infection control policies are important controlling the spread of VRE in high risk hospital zones. All endemic VRE strains are resistant to teicoplanin but are sensitive to daptomycin, linezolid, and tigecycline.

Keywords:
VRE; MLST; Outbreak; Inter-hospital spread