Vancomycin Resistance of Staphylococcus aureus in Korean Primary Hospitals

ABSTRACT

According to a United States study, 13 cases of vancomycin-resistant Staphylococcus aureus (VRSA) have been reported to date. In 2001, a survey conducted in Korea revealed that 0.5% of methicillin-resistant S. aureus (MRSA) isolates have a vancomycin minimum inhibitory concentration (MIC) of 4 microg/ml, and are thus referred to as vancomycin intermediate S. aureus (VISA). However there are no reports of VISA found in primary hospitals. We evaluated the MIC of vancomycin in MRSA samples obtained from primary hospitals to determine whether VISA was present in primary hospitals. The population analysis was performed to determine whether hetero-VISA was present in primary hospitals. As a result, twenty of the 103 isolates were S. aureus which were all MRSA and the vancomycin MIC was similar to that seen in tertiary hospitals. Population analysis confirmed that three strains were hetero-VISA, by showing that one strain grew in 8 microg/ml vancomycin and that two strains grew in 4 microg/ml vancomycin. In conclusion, hetero-VISA was detected in Korean primary hospitals, which may develop into VISA, however a larger sample size will be needed to confirm these results.