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.