Monitoring of methicillin resistant Staphylococcus aureus from medical environment in Korea

Methicillin-resistant Staphylococcus aureus (MRSA) is one of a major nosocomial pathogen worldwide and the emergence of this strain has become a major clinical problem. This study was performed for 13 hospitals with more than 400 beds in the country by collecting samples including hands and nasal cavities of doctors, nurses, guardians and patients. Also, additional 320 samples of hands and nasal cavities of 160 community resident in different locations and regions were collected. In all of medical environments and community resident, 625 strains of S. aureus were detected. Among 625 strains of S. aureus, 585 strains(93.6%) showed the resistance to at least one kind of antimicrobial and 112 strains (17.9%) showed multi-drug resistance with the resistance to 4 different types of antimicrobial. Total 152 MRSA strains (24.3%) were isolated from medical environment and community resident. In nasal cavity and hand, 49 MRSA (19.4%) and 103 (27.6%) MRSA were isolated, respectively. Minimum inhibitory concentration (MIC) test is used to measure for susceptibility of MRSA isolated to oxacillin. At a concentration 16 μg/ml of oxacillin, 11 strains were inhibited. 32 strains at 32 μg/ml, 41 strains at 64 μg/ml, 3 strains at 128 μg/ml, 25 stains at 256 μg/ml and 40 strains at over 256 μg/ml were inhibited. It was considered that medical environment showed higher than livestock and marine environments in MRSA detection rate.