Detection of ermAM Gene and mefA Gene in Erythromycin-resistant Streptococcus Pyogenes / 감염

ABSTRACT

BACKGROUND: The mechanism of erythromycin resistance of Streptococcus pyogenes results from target modification or active efflux. The purpose of this study was to determine the positive rate of ermAM gene modifying 23S rRNA and that of mefA gene related with efflux for erythromycin-resistant S. pyogenes. METHODS: The minimal inhibitory concentrations (MICs) of erythromycin, azithromycin, clarithromycin, and clindamycin against S. pyogenes were tested by agar dilution method. ermAM and mefA genes were amplified by polymerase chain reaction (PCR) for 32 strains of erythromycin-resistant S. pyogenes. RESULTS: Among the 32 erythromycin-resistant S. pyogenes strains, 20 (62.5%) strains were positive for ermAM gene and 10 (31.1%) for mefA gene. Eighteen (90.0%) out of 20 strains with ermAM gene showed high-level erythromycin resistance (MIC> OR =64 microgram/mL), while all ten strains with mefA gene had low-level erythromycin resistance (MIC< OR =16 microgram/mL). CONCLUSION: Two-thirds of the S. pyogenes strains acquired erythromycin resistance by modification of target site, while the others by active efflux. Each mechanism of resistance is closely associated with range of MICs of erythromycin.