SUSCEPTIBILITY OF ISOLATES OF NEISSERIA-GONORRHOEAE TO PENICILLIN AND TETRACYCLINE IN BROOKLYN, 1988-1992

Background and Objectives: The aim of this analysis was to determine the rate of resistance of Neisseria gonorrhoeae to penicillin and tetracycline over 5 years. Study Design: The authors studied 500 isolates of N. gonorrhoeae. Minimum inhibitory concentrations of various antimicrobial agents, including penicillins, tetracyclines, quinolones, cephalosporins, spectinomycin, and trospectomycin, were determined using agar dilution. Organisms that produced betalactamase were classified as penicillinase-producing N. gonorrhoeae, and those with tetracycline minimum inhibitory concentrations >16 mu g/ml were considered presumptive high-level tetracycline resistant. Organisms with Minimum inhibitory concentrations >2.0 mu g/ml were presumptively considered to have chromosomally mediated resistance to penicillin or tetracycline. Isolates with none of these forms of resistance were considered susceptible to penicillin and tetracycline. Results: Penicillinase-producing N. gonorrhoeae represented 34.7%, 40.7%, and 44.9% of gonococcal isolates in 1988, 1989, and 1990, respectively. Only 14.3% and 15.0% of the isolates in 1991 and 1992 were penicillinase-producing N. gonorrhoeae. In 1988, 1.0% of isolates were chromosomally mediated penicillin resistant. In contrast, chromosomally mediated penicillin resistant gonococci represented 7.5% to 22.4% of isolates from 1989 to 1992. In 1988, 26.0% of isolates were high-level tetracycline resistant. The prevalence of presumptive high-level tetracycline resistant organisms decreased after 1988. From 1989 to 1992, only 8.2% to 14.8% of gonococcal isolates were presumptive high-level tetracycline resistant. No chromosomally mediated tetracycline resistant isolates were identified in 1988. In 1989 and 1990, 11.6% and 10.2%, respectively, of isolates were chromosomally mediated tetracycline resistant. Chromosomally mediated tetracycline resistant N. gonorrhoeae represented 2.0% of isolates in 1991 and 25.0% of isolates in 1999. All isolates tested were susceptible to the other antibiotics. Conclusion: Continued surveillance of sensitivity of contemporary gonococci to antimicrobial agents is important.