The in vitro susceptibilities of 170 clinical isolates plus 12 American Type Culture Collection strains of Pasteurella species comprising nine species and three Pasteurella multocida subspecies were studied by an agar dilution method. Garenoxacin (BMS-284756), a new des-fluoro(6) quinolone, was active at <or=0.06 micro g/ml against all isolates, including four beta-lactamase-producing strains, with >90% of the strains susceptible to <or=0.008 micro g/ml. Garenoxacin was generally 1 to 2 dilutions more active than levofloxacin and moxifloxacin and was the most active agent tested. Cefoxitin required 1 micro g/ml for inhibition of 51 of 182 (29%) of strains, and 3 strains (also beta-lactamase producers) were resistant to doxycycline.