Characterization and comparative genital tract pathogenicity of bovine mycoplasmas.

Sixteen bovine genital mycoplasmal isolates obtained from semen and prepuce of bulls and from aborted fetuses were compared physiologically and serologically with the Donetta strain (tentatively Mycoplasma agalactiae var. bovis), a known pathogen. All isolates were distinct from the Donetta organism. Four appeared to be saprophytes, and the remainder were placed in one group which could not be further separated by the biochemical or serological methods used. Two of the organisms in the latter group have been subsequently identified as M. bovigenitalium. Uterine infusion of broth cultures of four isolates into virgin heifers failed to produce clinical evidence of disease, and significant lesions were not present at necropsy. The mycoplasmas were recovered from cervicovaginal mucus of only three heifers, and never for more than 3 days postinfusion. Since the organisms were not recovered from any organs at necropsy, it appears that the mycoplasmas were incapable of surviving in the clinically normal virgin female reproductive tract.