[In vitro susceptibility of Pasteurella and related bacteria to five orally administered antibiotics].

Tetracyclines and beta-lactam antibiotics are usually recommended for the treatment of pasteurellosis following bite wounds. However other oral antimicrobial agents could be proposed. In vitro susceptibility of 94 Pasteurella strains [P. multocida (79), P. stomatis (11), P. dagmatis (2), P. canis (1), P. "SP" (1)], 20 group EF-4 strains and 28 Neisseria weaveri strains (formerly group M-5), that are bacteria often isolated after animal-inflicted wounds, was studied towards five antibiotics: clarithromycin, azithromycin, pristinamycin, trimethoprim-sulfamethoxazole and ciprofloxacin. MICs were determined by the agar dilution method using HTM medium (Oxoïd), and for pristinamycin using both HTM and Mueller-Hinton agar supplemented with 5% horse blood (BMH). Most of Pasteurella isolates showed intermediate susceptibility to clarithromycin (63%) and to azithromycin (90.5%) with lower MICs for azithromycin. Fourty-two and thirty-two percent of Pasteurella strains were susceptible to pristinamycin respectively on HTM and on BMH. EF-4 and N. weaveri were more sensitive than Pasteurella to macrolides and to pristinamycin. Trimethoprim-sulfamethoxazole was active against all isolates, with higher MICs for EF-4 and N. weaveri. On all strains tested, the lowest MICs were observed for ciprofloxacin. Trimethoprim-sulfamethoxazole and ciprofloxacin could be proposed as a therapeutic alternative in case of pasteurellosis following animal bites.