건강인의 비인강내 MRSA 보균율과 methicillin 내성포구균에서의 mecA와 femA 유전자의 검출

Abstract

Nasal carriage rate and methiciliin resistance of Staphylococcus aureus in healthy adults are not well known in Korea. In this study, nasal specimens collected from college students during March to June, 1998 were cultured for S. aureus and the susceptibility of the isolates was determined by agar dilution method and the relationship of methicillin resistance level and β -lactamase production was analyzed. Also, presence of mecA andfemA was detected from the isolates by PCR. Isolation rate of S. aureus from the 339 subjects was 20%, and the rate was higher in female (21%) than in male (12%). Among the isolates, 2.1% were MRSAs. Against MSSA, clindamycin, fusidic acid, mupirocin and vancomycin were most active (MIC50 ≤1 μg⁄ml and MIC90 2 μg⁄ml) and the resistance rates to cephalothin, eηthromycin, gentamicin and tetracycline ≤20% and to chloramphenicol and penicillin G, were 73%. The MIC range of oxacillin against MRSA was 16-≥ 128 μg⁄ml, while MIC50 and MIC90 were 32 μg⁄ml and 128 μg⁄ml, respectively. Fusidic acid, mupirocin and vancomycin were most active against MRSA (both MIC50 and MIC90 were 1 μg⁄ml). Resistance rate of MRSA to clindamycin was 18%, but they were ≥ 59% to 6 other antibiotics. β -lactamase-producing strains were more prevalent among the low level methicillin-resistant isolates. mecA was detected from all MRSAs, but none from MSSAs. femA was detected from all of the MRSAs and MSSAs and none in coagulase-negative staphylococcus. In conclusion, healthy adults occasionally carry MRSAs, but they may have acquired them in hospitals. Fusidic acid and vancomycin should be useful to treat MRSA infection, while mupirocin should be useful to control nasalcarriage. mecA and femA may be used to differentiate MRSA from MSSA, and S. aureus from coagulsae-negative staphylococcus, respectively.