Isolation and Pathogenicity of Mycoplasmas from the Respiratory Tract of Calves

Abstract

Convincing evidence of pathogenicity has been obtained with only eight of the twelve species of mycoplasma which have hitherto been recovered from the respiratory tract of cattle. Mycoplasmc mycoides subsp. mycoides is the causal agent of contagious bovine pleuropneumonia and is relatively unimportant in Europe, except for occasional outbreaks on the Iberian peninsula. M. alkalescens, M. bovigenitalium and Leach’s Group 7 mycoplasmas have been rarely isolated from the respiratory tract: they are, however, capable of causing experimental mastitis in cattle but Koch’s postulates have not yet been fulfilled in respect of their aetiological role in pneumonia.

M. bovirhinis, M. bovis, M. dispar and Ureaplasma sp. are the mycoplasma species most frequently isolated from the respiratory tract of pneumonic calves. All are capable of producing experimental mastitis in cattle, although the mastitis induced by M. bovirhinis is only subclinical. M. bovis, M. dispar and Ureaplasma sp. are also capable of producing pneumonia when pure cultures are inoculated into gnotobiotic calves.