Sensitivities in vitro to Antibiotics of T-Mycoplasma and Mycoplanna bovirhinis Isolated from Calves

Abstract

Eleven strains of T-Mycoplasmas and 17 strains of Mycoplasma bovirhinis were examined for sensitivity to 15 antibiotics by the microtiter technique with the color change of the medium as an inhibiting end point. They had been isolated from the lungs of pneumonic calves and the vagina of normal ones.
All the T-Mycoplasma strains were highly sensitive to tetracycline-HCI, erthromycin, tylosin, and leucomycin at a concentration of 6.25mcg/ml or less, but were not so sensitive or rather resistant to any other antibiotic used. All the M. bovirhinis strains were sensitive to tetracycline-HO, tylosin, spiramycin, kanamycin, thiamphenicol, and lincomycin. Most of them were relatively sensitive to erythromycin, leucomycin, streptomycin, chloramphenicol, and furadiomycin, but were almost insensitive to oxytetracycline, oleandomycin, cefazolin, and ampicillin.