SUSCEPTIBILITIES OF CHLAMYDIA-TRACHOMATIS ISOLATES CAUSING UNCOMPLICATED FEMALE GENITAL-TRACT INFECTIONS AND PELVIC INFLAMMATORY DISEASE

The in vitro susceptibilities of 45 recent clinical isolates of Chlamy dia trachomatis obtained from women with asymptomatic genital tract in fection, mucopurulent cervicitis, or pelvic inflammatory disease to do xycycline, azithromycin, ofloxacin, and clindamycin were determined. I n addition, susceptibilities of 12 isolates to amoxicillin and trimeth oprim-sulfamethoxazole were also determined. Isolates also were seroty ped with a panel of monoclonal antibodies specific for chlamydial majo r outer membrane protein; 24 of 35 (53%) belonged to serovars Ia and E . For all isolates, the MIC range of doxycycline was 0.008 to 0.06 mu g/ml, for trimethoprim-sulfamethoxazole it was 0.03 to 0.25 mu g/ml, f or azithromycin it was 0.125 to 2.0 mu g/ml, for ofloxacin it was 0.5 to 1.0 mu g/ml, for clindamycin it was 0.25 to 2.0 mu g/ml, and for am oxicillin it was 0.25 to 4.0 mu g/ml. The ranges of minimum chlamydiac idal concentrations were generally 1 to 4 dilutions above the MICs of most agents, with a rank order similar to those of the MICs. Comparing the minimum chlamydiacidal concentrations for 90% of isolates tested, isolates causing asymptomatic infection belonged to a greater variety of serovars and were relatively more susceptible to doxycycline and a zithromycin than isolates causing mucopurulent cervicitis or pelvic in flammatory disease; these differences in susceptibility were not detec ted among the other study agents. These data indicate that additional studies are needed to better define the apparent association of certai n chlamydial serovars with the clinical severity of disease and the in vitro susceptibilities to certain antimicrobial agents.