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

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Indexed in KCI, KoreaMed, Synapse, DOAJ
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pISSN 2288-0585 eISSN 2288-6850

Comparison of mecA Gene Detection with Susceptibility Testing Methods in Coagulase Negative Staphylococcus According to the New NCCLS Guidelines (1999)

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2000 June Volume 3, Issue 1, pages 57-61.

Comparison of mecA Gene Detection with Susceptibility Testing Methods in Coagulase Negative Staphylococcus According to the New NCCLS Guidelines (1999)

Myung Hyun Nam, M.D., Hee Yeon Woo, M.D., Jang Ho Lee, M.T. and Nam Yong Lee, M.D.

Department of Clinical Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea

Abstract

Background: Coagulase negative staphylococcus (CNS) spp. is a major pathogenic organism of nosocomial and community-acquired urinary tract infections, and causes infections in the immunocompromised host, and, in particular, bloodstream infections in patients with indwelling devices. High prevalence of methicillin resistance has been noticed in CNS which also have been recognized as an important multidrug resistant pathogen. The optimal phenotypic method for detecting methicillin resistance still remains controversial, and new guidelines for detecting methicillin resistance of CNS was proposed by NCCLS in January 1999. We evaluated the relationship between mecA gene by PCR method and antimicrobial susceptibility tests according to the new NCCLS guidelines.

Methods: A total of 82 CNS isolates were examined for oxacillin MICs and penicillin MICs by disk diffusion and agar dilution method according to NCCLS guidelines, and detection of mecA gene by PCR.

Results: In disk diffusion method, 66 strains (80.5%) and 63 strains (76.8%) showed resistance to penicillin and oxacillin, respectively, and in agar dilution method, 71 strains (86.6%) and 53 strains (64.6%), respectively. In PCR method, mecA genes were detected in 49 strains (59.8%). Comparing with mecA gene detection by PCR method, the sensitivity of disk diffusion and agar dilution method was 95.8% and 89.8%, respectively. However, the sensitivity of disk diffusion and agar dilution method was 65.3% and 75.5%, respectively using previous NCCLS criteria.

Conclusion: The new criteria of NCCLS detects the methicillin resistance induced by mecA gene more sensitively than the previous one. (Korean J Clin Microbiol 2000;3(1):57-61)

Keywords

Coagulase negative staphylococcus, methicillin resistance, 1999 NCCLS criteria, mecA gene