In vitro activity of DU-6859a, a new fluorocyclopropyl quinolone

DU-6859a was tested against 844 recent clinical isolates (most from bacteremias) by using reference MIC determination procedures. The activity of DU-6859a against members of the family Enterobacteriaceae was comparable to that of ciprofloxacin (range of MICs for 90% of isolates [MIC90], < or = 0.015 to 1 microgram/ml), and the highest MICs were observed among Serratia marcescens and Providencia rettgeri isolates. The DU-6859a MIC90 for Pseudomonas aeruginosa and Xanthomonas maltophilia was 0.5 microgram/ml. Pneumococci (MIC90, 0.06 microgram/ml), Haemophilus influenzae (MIC90, < or = 0.004 microgram/ml), Moraxella catarrhalis (MIC90, < or = 0.015 microgram/ml), and pathogenic neisseriae (MIC90, 0.015 to 0.03 microgram/ml) were very susceptible to DU-6859a. All staphylococci had DU-6859a MICs of < or = 1 microgram/ml, including oxacillin- and ciprofloxacin-resistant strains. DU-6859a was very active against isolates resistant to ceftazidime (MIC90, < or = 0.12 microgram/ml), ciprofloxacin (MIC90, < or = 8 micrograms/ml), and gentamicin (MIC90, < or = 1 microgram/ml).