In vitro activity of fleroxacin against aerobic gram-positive bacteria including Corynebacterium jeikeium.

Fleroxacin (Ro 23-6240, AM-833), a new fluoro-4-quinolone, was tested in vitro against 273 gram-positive clinical isolates. Norfloxacin, a quinolone mostly used in urinary tract infections, was included as a standard. Overall, in vitro activities of fleroxacin and norfloxacin were superposable, but interestingly, fleroxacin was two- to fourfold more active against Staphylococcus aureus, and 1 mg/l of fleroxacin inhibited all 5 multiply resistant Corynebacterium jeikeium tested. While both quinolones were similarly active weight by weight, fleroxacin with its more favorable pharmacokinetic properties harbors the added promise of clinical usefulness in systemic infections against susceptible isolates.