Adult respiratory distress syndrome with or without systemic disease associated with infections due to Mycoplasma fermentans.

An unusual but typical clinicopathological presentation was noted among several groups of previously healthy, human immunodeficiency virus-negative patients who had an apparent fulminant infectious disease but had no etiologic agent identified. The clinical courses were characterized by rapid progression and development of adult respiratory distress syndrome with or without systemic disease. Histopathological changes in the diseases tissues (other than lung) obtained by biopsy or at autopsy ranged from extensive necrosis with only minimal inflammatory reaction to prominent lymphohistiocytic infiltrate with focal areas of acute inflammation. This report focuses on pulmonary changes in three patients. The alveolar epithelial (type I) cells and type II pneumocytes are diffusely damaged. There is interstitial edema and thickened septa. An eosinophilic alveolar membrane may form, and the alveolar space may fill with foamy macrophages. Immunohistochemical studies identified Mycoplasma fermentans infection in the patients' lungs and liver. Mycoplasma-like particles could also be identified by electron microscopy. There is a previously unrecognized form of fulminant disease in humans that is associated with M. fermentans infections.