In-vitro activity of azithromycin, erythromycin, dprofloxadn and norfloxadn against Neisseria gonorrhoeae, HaemophUus ducreyi, and

The minimum inhibitory concentrations (MICs) of azithromycin, erythromycin, ciprofloxacin and norfloxadn for 300 strains of Neisseria gonorrhoeae, 100 strains of HaemophUus ducreyi and six strains of Chlamydia trachomatis were determined. The two quinolones were more active against gonococcal strains than were the two macrolides. Azithromycin was approximately eight-fold more active against N. gonorrhoeae than was erythromycin (MIC ^ 0.25 mg/1 azithromycin, 2-Omg/l erythromycin). The Mtr phenotype of gonococci increased azithromycin MICs approximately four fold. Azithromycin was less active than erythromycin against C. trachomatis. Azithromycin had considerable activity against H. ducreyi and was ten-fold more active than was erythromycin (MIQo: 0-004 mg/1 azithromycin, 003 mg/1 erythromycin). Clinical trials of azithromycin in the treatment of chlamy-dial infection and genital ulcer disease are indicated