Pneumonia Due to Mycoplasma in Gnotobiotic Mice I. Pathogenicity of \u3cem\u3eMycoplasma pneumoniae\u3c/em\u3e, \u3cem\u3eMycoplasma salivarium\u3c/em\u3e, and \u3cem\u3eMycoplasma pulmonis\u3c/em\u3e for the Lungs of Conventional and Gnotobiotic Mice

Pneumonia due to mycoplasma in gnotobiotic mice. I. Pathogenicity of Mycoplasma pneumoniae, Mycoplasma salivarium, and Mycoplasma pulmonis for the lungs of conventional and gnotobiotic mice. J. Bacteriol. 92:1154–1163. 1966.—Two species of mycoplasma of human origin, Mycoplasma pneumoniae and M. salivarium, were tested for their ability to produce respiratory disease in the Ha/ICR mouse when inoculated by the intranasal route. The mouse pathogen M. pulmonis was studied as a positive control. Conventional and gnotobiotic Ha/ICR mice were employed, the latter to provide a system free from indigenous mycoplasma and bacteria. Pneumonia from which mycoplasma were isolated was produced in all groups of the conventional Ha/ICR mice, including those inoculated with sterile broth. Only M. pulmonis produced disease when inoculated intranasally into the gnotobiotic mice, and the gross and microscopic lesions resembled those described in conventional mice. The gnotobiotic mouse provided a tool to study the pathogenicity of different mycoplasma species, and indicated marked differences in host specificity that could not be clearly seen when conventional mice were used

Pneumonia due to Mycoplasma in Gnotobiotic Mice II. Localization of Mycoplasma pulmonis in the Lungs of Infected Gnotobiotic Mice by Electron Microscopy

Organick, Avrum B. (Marquette University School of Medicine, Milwaukee, Wis.), Kenneth A. Siegesmund, and Irving I. Lutsky. Pneumonia due to mycoplasma in gnotobiotic mice. II. Localization of Mycoplasma pulmonis in the lungs of infected gnotobiotic mice by electron microscopy. J. Bacteriol. 92:1164–1176. 1966.—Lesions in lungs of gnotobiotic mice inoculated intranasally with Mycoplasma pulmonis were examined by electron microscopy after osmic acid fixation. At 1 week after infection, mycoplasma cells were found in large numbers in the bronchi at the surface of bronchial epithelial cells and, in smaller numbers, in the alveoli where active phagocytosis by polymorphonuclear leukocytes (PMN) occurred. Cytopathic changes in underlying bronchial epithelial cells, not apparent by light microscopy, were observed. At 3 weeks after infection, mycoplasma cells were rarely seen in the bronchi, and were no longer seen free in the alveolar spaces or within PMN. Lungs examined after glutaraldehyde fixation 1 week after infection confirmed the presence of mycoplasma cells in the alveolar spaces and within phagocytic vacuoles of PMN, but also revealed numerous ring forms within granular pneumocytes. These forms seemed to represent intracytoplasmic developmental stages of M. pulmonis, in which elementary bodies appeared in large numbers