In vitro activity of ciprofloxacin compared with those of other new fluorinated piperazinyl-substituted quinoline derivatives.

The in vitro antimicrobial activity of ciprofloxacin (Bay o 9867) was compared with those of the other new fluorated piperazinyl-substituted quinoline derivatives: norfloxacin, ofloxacin, and pefloxacin, as well as with those of the earlier analogs, nalidixic acid and oxolinic acid. Virtually no resistance against the new fluorated piperazinyl-substituted quinoline derivatives was observed. As a rule, ciprofloxacin was about four times more active in vitro than the other new fluorated piperazinyl-substituted quinoline derivatives. The antibacterial spectrum of the new fluorated piperazinyl-substituted quinoline derivatives included, among other susceptible species, Pseudomonas aeruginosa, Streptococcus faecalis, Staphylococcus spp., and members of the family Enterobacteriaceae. In the case of ciprofloxacin, ofloxacin, and perfloxacin, anaerobes were included in the antibacterial spectrum as well. There was no cross resistance between the earlier analogs and the new fluorated piperazinyl-substituted quinoline derivatives. Regression analysis of MIC pairs for individual strains illustrated almost mathematical correlation between the antimicrobial activities of the quinoline derivatives.