RESUMO
BACKGROUND: About more than 70% of Staphylococcus aureus isolates in tertiary-care hospitals are known to be resistant to methicillin in Korea. But the prevalence of methicillin-resistant S. aureus (MRSA) in the community and non-tertiary hospitals has not been known yet. The aim of this study was to determine the prevalence of resistance among S. aureus isolates in non-tertiary hospitals. METHODS: The isolates were collected at one laboratory center from August 1998 to May 1999. Antimicrobial susceptibility tests against 11 antibiotics were performed by disk diffusion method. Minimum inhibitory concentrations (MIC) for oxacillin and vancomycin were determined by microbroth dilution method. The mecA gene was detected by polymerase chain reaction. The medical facilities which sent specimen to the laboratory were classified into 3 groups; clinic, hospital and general hospital. RESULTS: Of total 469 S. aureus isolates, 296 (63.1%) were from pus, 47 (10.0%) from sputum, 23 (5.0%) from urine, and 22 (4.6%) from blood. Overall prevalence of MRSA in non-tertiary hospital was 43.5% (204/469). Among 3 hospital groups, MRSA in general hospitals (55%) was significantly more prevalent than in hospitals (40%) or clinics (37%). MICs of oxacillin against MRSA isolated from pus and blood ranged from 8 to > or =256 microgram/mL, but 74% (83 isolates) of them was > or =256 microgram/mL. MICs of vancomycin were distributed from 1 to 2 microgram/mL, irrespective of methicillin resistance or hospital groups. The mecA gene was detected in all of methicillin-resistant isolates with MICs of < or =128 microgram/mL. CONCLUSION: In non-tertiary hospitals, 43% of S. aureus isolates were methicillin resistant. This result showed that MRSA in non-tertary hospitals was less prevalent than in tertiary hospitals.