Evaluation oftheStandardized DiskDiffusion andAgarDilution Antibiotic Susceptibility TestMethods byUsingStrains ofNeisseria gonorrhoeae fromtheUnited States andSoutheast Asia

Presently, mostNeisseria gonorrhoeae testing isbased onf-lactamase tests andagardilution withcommon therapeutic agents. TheNational Committee forClinical Laboratory Standards (NCCLS)recently described a diskdiffusion testthatproduced results similar tothereference agardilution methodfortheantibiotic susceptibility ofN.gonorrhoeae. We obtained 71gonococcal isolates fromactive-duty malesaboard aUnited States Navyvessel while deployed intheWestern Pacific during 1989. Inaddition, 47isolates ofN.gonorrhoeae wereobtained fromsexually transmitted disease clinics within thebranchclinic operations oftheNaval Hospital, SanDiego(SD), andtested. Antibiotic susceptibility tests byusing theNCCLSagardilution anddisk diffusion techniques werecompared. AmongtheSoutheast Asia(SEA)isolates, 47% were1i-lactamase producers compared with10.5%oftheSDisolates. ThemeanMICs(SEA/SD) inmicrograms permilliliter for bothgroups wereasfollows: penicillin, 88/15; tetracycline, 2.2/0.95; erythromycin, 1.2/0.49; ceftriaxone, 0.016/0.012; cefotaxime, 0.034/0.03; cefuroxime, 0.44/0.17; cefoxitin, 1.3/0.97; spectinomycin, 150/131; ciprofloxacin, 0.07/0.034; norfloxacin, 0.77/0.29; lomefloxacin, 0.15/0.056; andofloxacin, 0.07/0.036. The established NCCLS interpretive criteria forbothsusceptibility methodsappearapplicable todomestic gonococcal strains. However, modifications maybenecessary forthemoreantimicrobial agent-resistant SEA isolates onthebasis oftheclinical success andcurerates following theindicated single-dose regimens forthe geographic region. Theability ofbacteria todevelop resistance toantimicrobial agents hasbecomeasignificant problem inthetreatment andcontrol ofcommunicable sexually transmitted disease (1-8, 10,14,19-22). Thisisparticularly trueforNeisseria gonorrhoeae, whichhasevolved a numberofdifferent mechanisms toresist antimicrobial agents. Theemergence of penicillinase-producing