ABSTRACT
BACKGROUND: The aim of this study was to monitor trends in antimicrobial susceptibilities of Neisseria gonorrhoeae isolates, in particular, to examine the possibility of increasing prevalence of fluoroquinolone resistance in Korea and the relationship between patterns of mutations involving gyrA and parC genes and the ciprofloxacin resistance level. METHODS: The antimicrobial susceptibilities of 489 gonoccocal isolates which were nationwide collected from patients visiting Health Centers were determined by NCCLS disk diffusion and agar plate dilution methods. PCR and direct DNA sequencing of the amplicons were performed to identify mutations within the quinolone resistance-determining regions of gyrA and parC genes. RESULTS: The proportion of resistance to penicillin, tetracycline, or both remained as high as 94%. The isolates with ciprofloxacin resistance remarkably increased from 1% in 1999 to 5% in 2000 and also resistance to cefoxitine and ceftriaxone were shown to be increased. The strains resistant to spectinomycin was little reported. Four isolates with 16 microgram/mL of MIC for ciprofloxacin all showed the same alternations of Ser-91 to Phe, Asp-95 to Gly in GyrA and Ser-87 to Arg in ParC, but ciprofloxacin-susceptible strains have little amino acid substitution. CONCLUSION: Considering the increasing prevalence of isolates with resistance to ciprofloxacin and ofloxacin, it is likely that the antibiotics such as spectinomycin, or ceftriaxone are recommended as the first-line treatment for gonoccocal infections in Korea. The results from this study suggest that mutation analysis for quinolone resistance-determining regions of gyrA and parC genes are important in epidemiological studies for the spread of ciprofloxacin resistant strains.