A survey of Clostridium spiroforme antimicrobial susceptibility in rabbit breeding

Rabbit meat breeding may be heavily affected by enterotoxaemia due to Clostridium spiroforme. Data on its antimicrobial susceptibility are insufficient, presumably because of difficulties in cultivating and identifying the pathogen. Our aim is therefore to provide this information to veterinary practitioners by focusing on a panel of therapeutics used in intensive rabbit units. Lincomycin was also checked in order to investigate the origin of resistance to macrolides. Minimal inhibitory concentrations (MICs) were determined with the agar dilution method according to the CLSI M11-A7 protocol (2007). MIC50 and MIC90 were, respectively, 64 and 64 μg/ml for tiamulin, 32 and 32 μg/ml for norfloxacin, 0.063 and 0.125 μg/ml for amoxicillin, and 8 and 16 μg/ml for doxycycline. MIC50 and MIC90 were 256 μg/ml for sulphadimethoxine, spiramycin and lincomycin. Our results have shown that intrinsic or acquired antimicrobial resistances are diffuse in the C. spiroforme population and suggest focusing on prevention rather than on treatment of clostridial overgrowth, by reducing risk factors and using antimicrobials prudently.