An experimental model for human mycoplasma disease.

Development of animal models to explore possible relationships between mycoplasmas and chronic progressive respiratory disease of man could take two general courses. One approach could be study of naturally-occurring chronic respiratory diseases associated with mycoplasmas in animals and birds in order to gain insight into the nature of the host-parasite relationship that could be applied subsequently to investigation of human disease. A second approach could involve attempts to produce progressive disease in appropriate experimental hosts using mycoplasmas isolated from patients. There are a number of chronic respiratory mycoplasmoses of animals and birds: examples include infections with M. pulmonis in rats, M. hyo-rhinis in swine, and M. gallisepticum in turkeys. Discussion of the epidemiology and pathogenesis of these lesions will be provided by Drs. Fabricant and Thomas. At present no animal mycoplasmoses are known that have pathophysiologic features resembling chronic obstructive respiratory disease of man. Among the eight distinct mycoplasma species indigenous to man, only Mycoplasma pneumtoniae (Eaton's atypical pneumonia agent) has proven pathogenicity. Two other species are potentially pathogenic, although definitive proof is currently lacking. The first is M. hominis which has been associated with respiratory disease,"'2 has caused septicemia after obstetrical or gynecologic procedures,' and has produced exudative pharyngitis in volunteers.' The second is the T-strain group which is distinct from other mycoplasmas in biologic properties' and contains a multiplicity of serotypes ; these organisms have been associated with nongonococcal urethritis, but it is not clear whether they serve as primary or secondary invaders in this instance.' The remaining species (M. pharyngis, M. salivarium, M. orale types 2 and 3, and M. fermentans) have no known pathogenic significance, and apparently comprise part of the normal microbial flora of the respiratory and genito-urinary tracts. Isolation of these types from a variety of pathologic specimens, such as leukemic bone marrow, suggests that they