Mycoplasma hyopneumoniae の抗生物質感受性

A total of 54 strains of Mycoplasma hyopneumoniae isolated from porcine pneumonic lungs in Japan during 1970 to 1981 and neotype strain J were investigated for their in vitro susceptibility to 13 antibiotics. Of the drugs tested tiamulin showed the highest activity with minimal inhibitory concentration (MIC) of 0.02 or 0.04 μg/ml. Lincomycin and most of the macrolides and tetracyclines also showed low MIC values. The exceptional macrolide was erythromycin to which all the strains tested did not show significant susceptibility. Among tetracyclines, chlortetracycline (CTC) showed the lowest activity with MIC range from 2.5 to 40 μg/ml. Other tetracyclines, including tetracycline, oxytetracycline and doxycycline showed relatively broad MIC range from 0.04 to 2.5 μg/ml. Most of the strains isolated in 1970 were susceptible at the concentration of 5 μg/ml or lower to CTC and 0.16 μg/ml or lower to other tetracyclines, while only less than half of the strains isolated during 1979 to 1981 were susceptible at these concentrations. Aminoglycosides (neomycin and kanamycin) showed relatively high MICs for all the strains except for a few strains.