In vitro antibacterial activity of gemifloxacin and comparator compounds against common respiratory pathogens

This study investigated the in vitro potency of the novel quinolone agent g emifloxacin (SB-265805), in comparison with other quinolones, p-lactams, ma crolides and trimethoprim-sulphamethoxazole, against a panel of common resp iratory pathogens. This panel comprised recent clinical isolates of Strepto coccus pneumoniae (n = 347), Haemophilus influenzae (n = 256) and Moraxella catarrhalis(n = 184). Overall, the quinolones were highly active against i i. influenzae and were the most potent agents against M. catarrhalis. Gemif loxacin was the most potent quinolone tested against all three species and was four- to 512-fold more potent against pneumococci than trovafloxacin, g repafloxacin, levofloxacin, ciprofloxacin, ofloxacin, gentamicin, cefuroxim e, penicillin, ampicillin, clarithromycin, azithromycin or trimethoprim-sul phamethoxazole. Against 19 ofloxacin-intermediate and 52 ofloxacin-resistan t strains of S. pneumoniae, gemifloxacin retained activity, and was the onl y agent tested with MICs of less than or equal to 0.5 mg/L. The results of this study demonstrate the excellent in vitro antibacterial activity of gem ifloxacin against pathogens commonly associated with respiratory tract infe ctions and suggest that gemifloxacin has significant potential in the treat ment of such infections, including those caused by pneumococci considered r esistant to other quinolones.