Antibiotic susceptibility testing of Neisseria gonorrhoeae by disk-agar diffusion

Using two different culture media we have determined, by the agar dilution method, the minimal inhibitory concentrations of five antibiotics against eighty strains of Neisseria gonorrhoeae and compared the results with those obtained with the disk-agar diffusion technique. With one medium, under defined conditions of inoculum, we found a close statistical correlation for penicillin G, cefotaxime, tetracycline and thiamphenicol with linear regression coefficients (r) ranging from --0.9457 to -0.7400 but not for spectinomycin (r = -0.2503). The technique described also allows easy detection of beta-lactamase-producing strains of gonococci.