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 Original Articles |
| Molecular Epidemiological Study and Analysis of Genomic Diversity of mec Regulator Genes in mecA Positive methicillin-Resistant Staphylococci |
| Hee-Yeon Woo1, Nam-Yong Lee1, Sung-Ho Maeng2, Seung-Hoon Han, Kyung-Soo lhn, Sang-Wook Kim, Seung-Yong Seong, lk-Sang Kim, and Myung-Sik Choi |
| Department of Clinical Pathology, Samsung Medical Center, Sungkyunkwan University School
Of Medicine1 , Department of Phamacology2 and Department of Microbiology Seoul National University, College of Medicine, and Institute of Endemic Diseases, Seoul National University Medical Research Center
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Vol.18 Num.3 (p335~354)
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Background . High prevalence of methicillin resistance has been noticed in staphylococci which also have been recognized as important nosocomial and multi-drug resistant pathogens. In this study . we investigated the distribution of mec regulator genes and the presence of the mutation in mecⅠ gene to reveal the resistance mechanism at molecular level.
Methods : The isolates included 90 clinical isolates of MRSA 36 MRCNS of which methicillin resistance were determined by disk diffusion test and isolated in a single hospital during 1996-1999. We performed microdilution MIC test for oxacillin resistance and Kirby-Bauer test for other antibiotics. Genotypes of mecA positive (determined by PCR) isolates (78 MRSA, 36 MRCNS) were investigated by PCR amplification of mec regulator genes such as 3' end and 5' end of mecR1, mecⅠ and Pr-mecA.
Results : In MIC assay, all MRSA strains except 3 strains and all MRCNS strains showed oxacillin resistance. The level of resistance correlated to the multi-drug resistance. Seven genotypes were observed in mecA positive MRSA and MRCNS. Differences of predominant genotypes among years isolated and among species were observed. Deletions of the 3' end of mecR1 and the mecⅠ were more frequently observed in the low- and borderline-level resistant MRSA and MRCNS (P<0.05). So the important role of 3' end of mecR1 in determining resistance level was suggested.
Conclusion : This study demonstrated that genomic distribution of methicillin-resistant staphylococci isolated in Korea was different from that of strains isolated in other countries. And important role of mec regulator genes for expression of methicillin resistance was suggested. |
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Keywords : Methicillin-resistant staphylococci, mec regulator gene, Genotypes |
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