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

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Molecular Typing and Resistance Profiles of Vancomycin-Intermediate Staphylococcus aureus in Korea: Results from a National Surveillance Study, 2007-2013

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2016 December, Volume 19, Issue 4, pages 88-96.

https://doi.org/10.5145/ACM.2016.19.4.88

Molecular Typing and Resistance Profiles of Vancomycin-Intermediate Staphylococcus aureus in Korea: Results from a National Surveillance Study, 2007-2013

Jung Wook Kim, Gi Su Kang, Jae Il Yoo, Hwa Su Kim, Yeong Seon Lee, Jae-Yon Yu, Kwang-Jun Lee, Chan Park, Il-Hwan Kim

Division of Antimicrobial Resistance, Korea National Research Institute of Health, Korea Centers for Disease Control and Prevention, Cheongju, Korea

Abstract

Background: To investigate the national molecular epidemiology and resistance profiles of vancomycin- intermediate Staphylococcus aureus (VISA), we analyzed the characteristics of methicillin-resistant Staphylococcus aureus (MRSA) collected from clinical samples at tertiary or general hospitals participating in a nationwide surveillance program for VISA and vancomycin-resistant Staphylococcus aureus (VRSA) in Korea during an 12-week period in each year from 2007 to 2013.

Methods: VISA was defined by agar dilution, broth dilution and E-test methods with vancomycin minimum inhibitory concentrations of >2 μg/mL. All VISA isolates were characterized by multilocus sequence typing, staphylococcal cassette chromosome mec typing, spa typing, accessory gene regulator typing, Diversilab analysis, and antibiogram analysis.

Results: Of 109,345 MRSA isolates, 87,354 were screened and 426 isolates were identified as positive on brain heart infusion agar containing 4 μg/mL vancomycin (BHI-V4). Of 426 isolates, 76 isolates were identified as VISA. No VRSA isolates were detected among the isolates. Overall, a total of 6 genotypes were identified among VISA strains and the predominant clones were ST5-II-t2460, ST72-IV-t324, and ST239-III-t037 (44.7%, 15.8%, and 10.5%, respectively). Of note, ST72-IV-t324 clones are known to be a typical community-associated MRSA. ST239-III- t037 strains were more resistant to trimethoprim-sulfamethoxazole than any other type of strain. ST72- IV-t324 strains were susceptible to all of the antimicrobial agents tested except erythromycin and daptomycin. All of the VISA isolates were susceptible to linezolid and quinupristin-dalfopristin.

Conclusion: Although VRSA is still rare, continuous monitoring of VRSA occurrence is needed, as well as VISA prevalence, epidemic clonal shift, and antimicrobial resistance. (Ann Clin Microbiol 2016;19:88-96)

Keywords

Sequence type, Vancomycin-intermediate Staphylococcus aureus