Agar dilution method for susceptibility testing of Neisseria gonorrhoeae

The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending a clinic for sexually transmitted diseases in Tucuman, Argentina, were determined by the agar dilution method (MIG). 3.5% of the isolates produced beta-lactamase. A total of 96.5% of beta-lactamase negative isolates tested were susceptible to penicillin (MIC less than or equal to 2 mu gml(-1)); 14.03% of the tested isolates were resistant to tetracycline (MIC less than or equal to 2 mu gml(-1)), and 98% of the tested isolates were susceptible to spectinomycin (MIC less than or equal to 64 mu gml(-1)). The MICs for 95% of the isolates, tested for other drugs were: less than or equal to 2 mu gml(-1) for cefoxitin, less than or equal to 0.06 mu gml(-1) for cefotaxime, less than or equal to 0.25 mu gml(-1) for norfloxacin, less than or equal to 10 mu gml(-1) for cephaloridine, less than or equal to 10 mu gml(-1) for cephalexin, and 150 mu gml(-1) for kanamycin. Antibiotic resistance among N. gonorrhoeae isolates from Tucuman, Argentina appeared to be primarily limited to penicillin and tetracycline, which has been a general use against gonorrhoeae in Tucuman since 1960. Periodic monitoring of the underlying susceptibility profiles of the N. gonorrhoeae strains prevalent in areas of frequent transmission may provide clues regarding treatment options and emerging of drug resistance.