Antibacterial Activity of Florfenicol Combinations against E.coli Producing Extend-spetrum Beta-lactamases in Chickens

To determine the antibacterial activity of florfenicol combinations against E.coli produc-ing extend-spetrum beta-lactamases(ESBLs) in chickens,the minimum inhibitory concentrations(MIC) of florfenicol,colistin,ceftiofur,amikacin,doxycycline,amikacin,fosfomycin and the diffe-rent percentage of florfenicol combinations against the E.coli isolates,which producing ESBLs determined by slip diffusion method,were determined by using liquid double microdilution method.The results showed that all of the seven strains isolated from chicken were ESBLs-producing strains and the rates of drug resistance of florfenicol,ceftiofur,maquindox,amikacin,doxycycline and fosfomycin were 100%,100%,100%,71%,57% and 57%,respectively.The MIC of florfenicol combinations was lower than that of single drug.The best effect was obtained when florfenicol and doxycycline were combined.