A micro-organism, previously known as the J agent, was grown on solid medium: its various characteristics suggested that it was a mycoplasma and it was provisionally named Mycoplasma suipneumoniae.
In the growth-inhibition and metabolic-inhibition tests, M. suipneumoniae was indistinguishable from M. hyopneumoniae (Maré & Switzer, 1965).
By the growth-inhibition test, M. suipneumoniae seemed unrelated to all of a wide range (42 strains) of other mycoplasmas examined. These results suggest that, if the similarity between M. suipneumoniae and M. hyopneumoniae is substantiated in further work, these latter two strains are probably a new species.
M. suipneumoniae was also identified by the metabolic-inhibition test, by precipitation in agar gel, and by immune-fluorescence. Using the last two methods, M. suipneumoniae was distinguished from a second porcine mycoplasma (strain 603).
The most important property of M. suipneumoniae is its ability to induce enzootic pneumonia experimentally in pigs.