The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending sexually transmitted disease clinics in Cholburi and Bangkok, Thailand, were determined by agar dilution. Some 28.2% of isolates produced 13-lactamase. A total of 97.9% of 13-lactamase-positive and 51% of 1-lactamase-negative isolates tested were resistant to penicillin (MICs, 22 ,ug/ml), 70%o of isolates tested were resistant to tetracycline (MICs, >2 ug/ml), and 91% of isolates tested were susceptible to spectinomycin (MICs, c64 ,ug/ml). The MICs for 90% of isolates for the other drugs tested were 2 ,ug/ml for erythromycin, 2 img/ml for cefoxitin, 1 p,g/ml for cefuroxime, 0.125 ,ug/ml for cefpodoxime, 0.06 ,ug/ml for cefotaxime, 0.25 ,ug/ml for ceftazidime, 0.03 ,ug/ml for ceftizoxime, 0.03 ,ug/ml for ceftriaxone, 0.03 ,ug/ml for cefixime, 0.06 ,ug/ml for aztreonam, 0.008 ,ug/ml for ciprofloxacin, 0.125 p,g/ml for norfloxacin, and 0.075 ,ug/ml for ofloxacin. Fewer than 1.5% of isolates were resistant to the extended-spectrum cephalosporins tested. Some 0.3% or fewer isolates were resistant to broad-spectrum cephalosporins, fluoroquinolones, or the monobactam aztreonam.
