Comparison of in vitro activities of DU-6859a and other fluoroquinolones against Japanese isolates of anaerobic bacteria.

The in vitro activity of DU-6859a, a new fluoroquinolone, was compared with those of other fluoroquinolones against clinical isolates of anaerobic bacteria and Gardnerella vaginalis. DU-6859a was the most active agent; it inhibited 90% of isolates of almost all species tested, including Bacteroides fragilis at < or = 0.39 micrograms/mL. Although the other quinolones tested were active against gram-positive anaerobes, inhibiting their growth at < or = 1.56 micrograms/mL, these agents were less active against the B. fragilis group and Prevotella bivia (90% of which were inhibited at > or = 6.25 micrograms/mL). Mobiluncus species and G. vaginalis, which are well associated with bacterial vaginosis, were inhibited by DU-6859a at 0.1 microgram/mL. These results suggest that DU-6859a is a promising oral agent for the treatment of bacterial infections due to anaerobic bacteria; however, further studies, including determination of vaginal levels of this compound, should be performed to study the role of DU-6859a in the treatment of bacterial vaginosis.