In vitro activity of fleroxacin (Ro23-6240), a new fluorinated 4-quinolone against isolates from cancer patients.

The in vitro activity of Fleroxacin (Ro23-6240; AM 833), a new fluorinated 4-quinolone, was compared to that of ciprofloxacin, enoxacin and A-56620, against 747 isolates from cancer patients. Fleroxacin inhibited more than 90% of Enterobacteriacea isolates at a concentration of less than or equal to 0.25 micrograms/ml. It was also extremely active against Aeromonas hydrophila and Haemophilus influenzae isolates with MIC90 values of 0.12 and 0.06 micrograms/ml, respectively. The MIC90 for Acinetobacter spp. was 1.0 micrograms/ml, for Pseudomonas aeruginosa and Pseudomonas fluorescens 4.0 micrograms/ml, and for other Pseudomonas spp., 8.0 micrograms/ml. Staphylococcus aureus isolates including methicillin-resistant strains were inhibited by less than or equal to 1.0 microgram/ml. The MIC90 for three different species of coagulase-negative Staphylococci was 1.0 microgram/ml. Streptococcal species required 8-16 micrograms/ml for inhibition. Fleroxacin was also active against group JK-diphtheroids and Bacillus cereus. The overall activity of fleroxacin was similar to that of enoxacin and less than that of A-56620 and ciprofloxacin.