INVITRO ACTIVITY OF AZITHROMYCIN AGAINST CHLAMYDIA-TRACHOMATIS

We evaluated the efficacy of azithromycin, erythromycin and doxycycline in controlling in-vitro propagation of Chlamydia trachomatis in HeLa 229 cells. Eight recent clinical isolates of C. trachomatis and two fast-growing strains were tested with inocula of 103–105 inclusion forming units per well of a 96-well microtitre plate. C. trachomatis inclusions were detected by an immunoperoxidase-antiperoxidase procedure (PAP), including a genus-specific monoclonal antibody. MIC ranges were 0.064–0.25 mg/l azithromycin, 0.064–0.128 mg/l erythromycin and 0.016–0.064 mg/l doxycyline; MBC ranges were 2–8 mg/l azithromycin, 4–64 mg/l erythromycin and 0.5–8 mg/1 doxycycline. Since azithromycin appears to be effective against C. trachomatis, clinical studies in sexually transmitted diseases are indicated. © 1990 The British Society for Antimicrobial Chemotherapy.