Comparative in vitro activity of lomefloxacin, a new difluoroquinolone

The in vitro activity of lomefloxacin, a new difluoroquinolone, was compared with that of norfloxacin, ciprofloxacin, gentamicin and ceftazidime against a total of 577 recent clinical isolates. MICs were determined by a standard agar dilution procedure, and two inocula (10(4) and 10(6) CFU) were used throughout. Lomefloxacin inhibited most species of the Enterobacteriaceae, Staphylococcus aureus (including methicillin-resistant strains) and Haemophilus influenzae at less than or equal to 1 mg/l. Pseudomonas aeruginosa (MIC 90, 4 mg/l) was somewhat more resistant, and Pseudomonas maltophilia (MIC 90, 16 mg/l) and the Bacteroides fragilis group (MIC 90, 32 mg/l) were considerably more resistant. Overall, lomefloxacin was as active as norfloxacin, but was two- to eightfold less active than ciprofloxacin against most species tested.