In-vitro activity of lomefloxacin (SC-47111) and other quinolones.

The in vitro activity of lomefloxacin, a new difluorinated quinolone, was compared to that of ciprofloxacin, ofloxacin, norfloxacin and other relevant antibacterial agents. Lomefloxacin and norfloxacin shared similar activity, whereas ofloxacin and in particular ciprofloxacin showed superior activity. Most gram-negative aerobes were susceptible to all four quinolones, 90% of isolates were inhibited by 1 mg/l. The gram-positive organisms were generally less susceptible, although 90% of Staphylococcus aureus isolates were inhibited by 0.5 mg/l of ciprofloxacin and ofloxacin; values for lomefloxacin and norfloxacin were 1 mg/l and 2 mg/l, respectively; susceptibility was not affected by methicillin resistance. Neisseria gonorrhoeae and Haemophilus influenzae were highly susceptible to the quinolones, especially ciprofloxacin. Penicillin/ampicillin-resistant isolates remained susceptible to the quinolones.