Role of viable mycoplasmas in the pathogenesis of arthritis induced by M. pulmonis.

The role of viable M. pulmonis organism in the pathogenesis of both the acute and chronic phases of M. pulmonis-induced arthritis was examined. In the acute phase of the arthritis most clinically involved joints contained organisms and the degree of clinical arthritis in a given joint correlated with the number of organisms isolated. The more severe the acute arthritis, the more frequently the M. pulmonis organism was isolated from the joints during the chronic phase. In the chronic phase, arthritis defined histologically correlated with the presence of M. pulmonis organisms within a given joint. No correlation was observed between clinical arthritis during the chronic phase and histopathology or the presence of M. pulmonis organisms within the joint. In chronically infected mice, M. pulmonis was isolated from the joints only but not from the blood, liver, spleen, lung or kidney of any mouse examined. The results support the concept that viable organisms play an essential role in the pathogenesis of the acute and chronic phases of M. pulmonis-induced arthritis in mice.