Showing papers in "American Journal of Respiratory and Critical Care Medicine in 1974"

Appearance of Mycoplasma pneumoniae in lungs of experimentally infected hamsters and sputum from patients with natural disease

Abstract: tion in graded ethanol and embedding in Epon. Thick (l-,um) sections were stained with Richardson's blue for light microscopy; thin sections were cut in areas where cellular infiltrate was present and were stained with uranyl acetate and lead citrate for electron microscopy. Densely staining Mycoplasma pneumoniae with a filamentous appearance and a specialized terminal structure were found in medium-sized bronchi in areas where peribronchial infiltration was present. The organisms were attached to the lumenal respiratory epithelial surface by their ter­ minal organelles. Sputum samples from 18 patients with natural Mycoplasma pneumoniae disease proved by culture were studied for further insight into disease mechanisms and diagnostic features. Quanti­ tative mycoplasma cultures of 10 samples yielded 102 to 106 colony-forming units per ml of sputum (geometric mean value: 104 . 1). Wright's stain smears for cytologic studies revealed a pre­ dominance of polymorphonuclear leukocytes, with large mononuclear cells and desquamated cili­ ated epithelial cells in some specimens. Portions of the sputum samples were processed for electron microscopy. As in the experimental models, the mycoplasma was identified by its characteristic dense staining, size, and filamentous appearance. Organisms were found attached to epithelial cell lumenal membranes, microvilli, and cilia by their differentiated terminal structures. Interpretation of the diagnostic specificity of the cytologic features awaits comparable studies in other diseases. The degree of infectivity of sputum implies that visualization of organisms may be accomplished readily with appropriate techniques. These studies substantiate the morphol~gy of the mycoplasma's parasitic form, which has been suggested by previous studies in vitro, and reveal the nature of the host-parasite relationship in man.