Incidence, epidemiology and evolution of reduced susceptibility to ciprofloxacin in Neisseria gonorrhoeae in Korea

ObjectiveTo verify the decrease of susceptibility to ciprofloxacin in Neisseria gonorrhoeae, determine the size of the recently reported new β-lactamase plasmid and explain the high prevalence of penicillinase-producing Neisseria gonorrhoeae (PPNG).MethodsGonococci were isolated from prostitutes in Korea. Antimicrobial susceptibility was tested by NCCLS disk diffusion and agar dilution methods. Plasmid was isolated by an alkaline lysis method. Patterns of NheI-digested genomic DNA were compared after pulsed-field gel electrophoresis (PFGE).ResultsThe minimum inhibitory concentration of ciprofloxacin for 50% of the isolates rose from 0.015 mg/L in 1993 to 0.12 mg/L in 1996. The proportion of PPNG remained at 70% or over during the 5-year period. The size of a novel β-lactamase plasmid, first reported in 1994, was determined to be approximately 3.2 MDa, and 48% of the PPNG isolates contained it. Twelve of 50 isolates had the same PFGE pattern and nine others another pattern.ConclusionThe rapid decrease of fluoroquinolone-susceptible gonococci suggests that in the near future the drug may become less useful for gonorrhea treatment. The new 3.2-MDa plasmid may have been introduced as a result of the recent increase in overseas travel. The PFGE pattern suggests that high prevalence of PPNG may be due to dissemination of a few resistant clones among the high-risk groups