Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


Weeks in Review


Weeks to Publication
Indexed in KCI, KoreaMed, Synapse, DOAJ
Open Access, Peer Reviewed
pISSN 2288-0585 eISSN 2288-6850

Comparison of Multilocus Sequence Typing Change Patterns of Vancomycin-Resistant Enterococcus faecium from 2015 to 2017

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2017 September, Volume 20, Issue 3, pages 67-73.

Comparison of Multilocus Sequence Typing Change Patterns of Vancomycin-Resistant Enterococcus faecium from 2015 to 2017

Joon Kim1, Young Ihn Kwon2, Wee Gyo Lee3
1Department of Medical Sciences, The Graduate School, Ajou University, Suwon, Korea, 2Undergraduate Statistics, Indiana University, Bloomington, USA, 3Department of Laboratory Medicine, Ajou University College of Medicine, Suwon, Korea


Background: Multilocus sequence typing (MLST) is useful in determining the long-term evolutionary process and minimizes differences in experimental results across individuals and laboratories. It is also useful in determining evolutionary origins and backgrounds of bacterial species. This study carries out MLST analysis on VanA-type vancomycin-resistant Enterococcus faecium isolated from patient specimens in a single university hospital over nine years in order to observe changes in genetic evolution over time.

Methods: During the years from 2007 to 2015, 44 clinical isolates of vanA-containing E. faecium were collected from Ajou University Hospital in Korea. Species were identified by the VitekII system (bioMerieux, USA), and antibiotic susceptibility testing was performed by disk diffusion and E-test according to Clinical and Laboratory Standards Institute (CLSI) guidelines. To determine genetic relatedness, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF M/S) was employed. To characterize clonal diversity, MLST analysis was used.

Results: All isolates were highly resistant to ampicillin, ciprofloxacin, and vancomycin but showed variable levels of resistance to teicoplanin. The 44 clinical isolates were genetically unrelated according to MALDI-TOF M/S analysis. MLST showed that the clinical isolates harbored 6 sequence types (ST), with ST17 (n=19) being the most common, followed by ST78 (n=13), ST192 (n=6), ST64 (n=4), ST262 (n=1), and ST414 (n=1).

Conclusion: The MLST analysis showed that the sequence types of most isolates belonged to clonal complex 17 This is consistent with outbreaks in hospitals. We had single observations for ST262 and ST414, suggesting that they were random occurrences. MLST can be useful for speculating the genetic evolution of VanA-containing E. faecium isolates. (Ann Clin Microbiol 2017;20:67-73)