Combination Antibacterial Effect of Enrofloxacin and Other Antimicrobial Agents against Mycoplasma gallisepticum in vitro

The minimal inhibitory concentrations(MIC) of nine antibacterial drugs for Mycoplasma gallisepticum BG44T strain were determined by two-fold dilution method. Antibacterial effects of 8 kinds of drug combinations for M. gallisepticum BG44T strain were evaluated by determining the fractional inhibitory concentration index(FIC) with chessboard method. The MICs of enrofloxacin、tilmicosin、tylosin、kitasamycin、lincomycin、valnemulin、tiamulin、chloroamphenicol、florfenicol were 0. 063,0. 004,0. 016,0. 063,16, 0. 004,0. 008,8 and 8 μg / mL,respectively. Additive effects were observed for the combination of enrofloxacin with tilmicosin,tylosin,kitasamycin,lincomycin,valnemulin and tiamulin,while the effect of combined inhibition wasantagonism for the combination of enrofloxacin with chloroamphenicol and florfenicol.