Susceptibility of Neisseria gonorrhoeae associated with pelvic inflammatory disease to cefoxitin, ceftriaxone, clindamycin, gentamicin, doxycycline, azithromycin, and other antimicrobial agents.

We determined the susceptibilities, by the agar dilution method, of 84 recent clinical isolates of Neisseria gonorrhoeae obtained from women with pelvic inflammatory disease in the United States to the following antimicrobial agents: penicillin, cefoxitin, cefotetan, ceftriaxone, ceftizoxime, cefixime, tetracycline, doxycycline, ciprofloxacin, ofloxacin, erythromycin, azithromycin, clindamycin, and gentamicin. Twenty-five percent of the isolates were resistant to penicillin and 20% were resistant to tetracycline. In comparison, doxycycline was more active than tetracycline and azithromycin was more active than erythromycin in vitro. Ceftriaxone, ceftizoxime, and cefixime were equally active against penicillin-susceptible isolates, but they had different in vitro activities against gonococcal isolates possessing chromosomally mediated resistance to penicillin. Overall, cefoxitin was slightly more active than cefotetan and ciprofloxacin was more active in vitro than ofloxacin, especially against N. gonorrhoeae with chromosomally mediated resistance. Criteria for the interpretation of susceptibility data for N. gonorrhoeae are not available for clindamycin or gentamicin, but for at least half of all isolates, including penicillin-susceptible isolates, at least 4 micrograms of clindamycin or gentamicin per ml was required to inhibit growth in vitro.