Epidemiological characteristics and molecular basis of fluoroquinolone-resistant Neisseria gonorrhoeae strains isolated in Korea and nearby countries.

OBJECTIVES This study was performed to examine the cause of the increase in quinolone-resistant Neisseria gonorrhoeae (QRNG) observed in Korea. METHODS The antimicrobial susceptibilities of 190 isolates of gonococci from Korea in 2000 were examined by NCCLS methods, and subsets of these isolates underwent mutation analysis of the quinolone resistance-determining regions (QRDRs) of gyrA and parC. Molecular epidemiological characterization of 25 Korean isolates and 54 isolates from overseas was performed by pulsed-field gel electrophoresis (PFGE) and the results compared. RESULTS Most (172, 90.5%) of the 190 gonococci tested displayed reduced susceptibility to ciprofloxacin. All strains with high-level ciprofloxacin resistance (ciprofloxacin MIC >/= 4 mg/L) contained a double amino acid alteration at the 91 and 95 positions in the QRDR of GyrA and a single alteration in ParC. PFGE types of high-level QRNG in Korea were mostly different from those of other nearby countries. CONCLUSIONS These results suggest that the observed increase in ciprofloxacin-resistant isolates is due to the mutation and spread of Korean multiclonal isolates rather than importation from overseas.