Attempts to recoverMycoplasma suipneumoniaefrom experimental and natural cases of enzootic pneumonia in pigs

Abstract

Two strains of enzootic pneumonia, which are regularly free from mycoplasmas other thanMycoplasma suipneumoniae, were transmitted experimentally to a total of 22 pigs.M. suipneumoniaewas recovered in liquid medium from the lung lesions in 20 of these animals (91%).Twelve field outbreaks of enzootic pneumonia were likewise examined forM. suipneumoniae: from each outbreak, cases were selected where many mycoplasmas with the morphology ofM. suipneumoniaewere seen in touch preparations made from the lung lesions.M. suipneumoniaewas recovered from only two of these outbreaks, butM. hyorhiniswas obtained from nine of them.To establish whether the outbreaks yielding onlyM. hyorhiniswere indeed enzootic pneumonia, material from five of them was used in disease-transmission experiments: enzootic pneumonia was induced in every instance, andM. suipneumoniaewas recovered from three of the five transmitted strains.It is concluded thatM. hyorhinisis commonly present in the lung lesions of enzootic pneumonia and that this mycoplasma may often prevent the isolation ofM. suipneumoniae. The problem of recoveringM. suipneumoniaein this situation is made more difficult by the fact that in no instance whereM. suipneumoniaewas isolated directly in liquid medium was it cultured in parallel on solid medium.