Comparative bacterlostatic, and bactericidal activities of levofloxacin against clinical Pasteurella isolates

The MICs of seven quinolones, nalidixic acid, pefloxacin, ofloxacin, d-oflo xacin, ciprofloxacin, sparfloxacin and levofloxacin, were determined by aga r dilution method comparatively to those of amoxycillin, cefpodoxime, doxyc yclin and clarithromycin against 75 clinical isolates of Pasteurella multoc ida, P. dagmatis and P. canis. Time-kill method was performed for three sel ected R multocida isolates. Fluoroquinolones were the most active agents. A t concentration of 0.016 mg/L of sparfloxacin or levofloxacin the 75 isolat es were inhibited. The MICs of levofloxacin and sparfloxacin showed that th e activity of these molecules was two to four times higher than that of the other quinolones studied. Time-kill studies showed a complete killing in s ix hours with the CMI x 2 of pefloxacin, ofloxacin, ciprofloxacin, sparflox acin and levofloxacin. This result was obtained more rapidly with the quino lones than with amoxicillin or cefpodoxime. Doxycycline and clarithromycin were devoid of bactericidal activity. (C) 2001 Editions scientifiques et me dicales Elsevier SAS.