In vitro activity of the two new 4-quinolones A56619 and A56620 against Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum and Gardnerella vaginalis.

The in vitro activity of tetracycline, ciprofloxacin and two recently developed 1-aryl-fluoroquinolones, A56610 and A56620, was tested against 65 beta-lactamase-negative and 35 beta-lactamase-positive Neisseria gonorrhoeae strains, 12 Chlamydia trachomatis, 50 Mycoplasma hominis, 28 Ureaplasma urealyticum and 50 Gardnerella vaginalis strains. In the case of Chlamydia trachomatis and Mycoplasma hominis both the MIC and the MBC were determined. The MIC90 of ciprofloxacin for Neisseria gonorrhoeae was 0.008 microgram/ml and of A56619 and A56620 less than or equal to 0.03 microgram/ml. No difference was observed between the activity against beta-lactamase-negative and beta-lactamase-positive strains. The MIC90 values of of ciprofloxacin and A56620 for Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum were identical, the values being 2 micrograms/ml, 1 micrograms/ml and 4 micrograms/ml respectively. The MIC90 of A56619 for Chlamydia trachomatis and Ureaplasma urealyticum was 0.5 micrograms/ml and 1 microgram/ml respectively. The MBC90 values of the three quinolones for Chlamydia trachomatis and Mycoplasma hominis were less than or equal to 2 micrograms/ml. The activity of the quinolones against Gardnerella vaginalis was rather low, the MIC90 being greater than or equal to 4 micrograms/ml. It is concluded that A56619 and A56620 might be useful for single-dose therapy of gonococcal infections.