Sensitivity of certain porcine and bovine mycoplasmas to antimicrobial agents in a liquid medium test compared to a disc assay.
The sensitivity of some porcine and bovine mycoplasmas to potent antimicrobial agents was examined. Minimum inhibitory concentration (MIC) values were estimated for M. hyosynoviae, M. hyopneumoniae, M.dispar amd M. bovis against enrofloxacin, lincomycin, tetracycline, tiamulin and tylosin, in a liquid medium test and in a disc assay. All 6 examined strains of each species and the respective type strains were significantly inhibited. The greatest sensitivity was noted for tiamulin against strains of M. hyosynoviae with a final MIC50 broth value of 0.025 µg/ml and disc value of 0.03 µg per disc. Enrofloxacin was very potent against M. hyopneumoniae with a final MIC50 of 0.025 µg/ml and 0.1 µg per disc, and for M. dispar with 0.05 µg ml-1 and 0.03 µg per disc. Most disc assay estimates in µg per disc were similar to or moderately greater than corresponding final broth figures in µg/ml. It may be possible to convert observed disc assay values into representative final broth MIC values for use in the clinic.