Gonococcal antibiotic resistance in Los Angeles.

One hundred and thirty-five gonococcal isolates collected from Los Angeles in 1972 were studied for antibiotic susceptibility to penicillin, ampicillin, carbenicillin, tetracycline, minocycline, doxycycline and spectinomycin. Only 12 percent of the isolates were sensitive to 0.05 mug per ml of penicillin while 35 percent required at least 0.5 mug per ml for inhibition of growth. The results were slightly better with ampicillin and nearly the same with carbenicillin. Nineteen percent of the isolates required at least 1.0 mug per ml of tetracycline for inhibition of growth and the results were similar with either minocycline or doxycycline. Forty-nine percent were sensitive to 2.0 mug per ml spectinomycin, but 37 percent required at least 8.0 mug per ml for inhibition of growth. In this study nine of eleven isolates resistant to 1.0 mug per ml of tetracycline were also resistant to both penicillin and spectinomycin. Six came from endocervical sites of female patients who contributed only 37 percent of the total number of isolates studied. Correlation between the agar dilution and disc diffusion methods was satisfactory with penicillin but not with ether tetracycline or spectinomycin.