The emergence of Neisseria gonorrhoeae with decreased susceptibility to ciprofloxacin in Cleveland, Ohio: Epidemiology and risk factors

Background: Until 1992, almost all strains of Neisseria gonorrhoeae that had been tested in the United States were susceptible to fluoroquinolones, including ciprofloxacin. However, among men with urethral gonococcal infections who attended one sexually transmitted disease clinic in Cleveland, Ohio, the prevalence of gonococci with decreased susceptibility to ciprofloxacin increased from 2% in 1991 to 16% in 1994. Objective: To describe the emergence of and risk factors for gonococcal urethritis caused by gonococci with decreased susceptibility to ciprofloxacin. Resistance to ciprofloxacin was considered to be decreased if the mean inhibitory concentration was at least 0.12 mu g/mL and was less than or equal to 0.25 mu g/mL; this definition did not equate with the definition of clinical resistance. Design: Case-control study. Setting: An urban sexually transmitted disease clinic. Participants: 51 case-patients and 106 controls. Measurements: Pulsed-field gel electrophoresis was used to identify individual genotypes of ciprofloxacin-resistant and ciprofloxacin-susceptible isolates. Results: 55 of the 746 isolates of N. gonorrhoeae that were tested (7.4%) had decreased susceptibility to ciprofloxacin, and the prevalence of N. gonorrhoeae with decreased susceptibility significantly increased during the study period. Case-patients were significantly less likely to have gram-negative diplococci seen on microscopic examination of urethral discharge (P less than or equal to 0.01) and were less likely to be treated for gonococcal urethritis than were controls (P less than or equal to 0.001). Molecular typing suggested the spread of a single genotype of N. gonorrhoeae. Conclusions: Strains of gonococci with decreased susceptibility to ciprofloxacin appear to have become endemic in Cleveland, Ohio. The clinical significance of these isolates is not clear, but the potential for the emergence of clinically important resistance may preclude the use of fluoroquinolones as an alternative treatment for uncomplicated gonorrhea.