HUMAN INFECTION FROM AN UNIDENTIFIED ERYTHROCYTE-ASSOCIATED BACTERIUM

A 49-year-old splenectomized man had an infection from an unidentified, gram-positive, rodshaped bacterium that adhered to the majority of his peripheral-blood erythrocytes. On transmission electron microscopy, the bacterium was seen to be extraerythrocytic and was 0.2 μm wide by 1.0 to 1.7 μm long. It possessed a thick, granular cell wall, a trilamellar membrane external to the cell wall and prominent mesosomes. Attempts to cultivate the organism in vitro or to duplicate the patient's disease in splenectomized animals were unsuccessful. The patient's response suggested that the bacterium was susceptible to cell-wall-active antibiotics and to chloramphenicol but not to tetracycline. This bacterium may be the cause of other chronic, fever-producing, multisystem diseases of unknown origin. (N Engl J Med 301:897–900, 1979) INFECTIOUS agents that parasitize erythrocytes are rarely acquired by human beings in the continental United States. Only the protozoa causing babesiasis and malaria are accepted as human red-cell pathogens.1,2 In this report we describe an illness in which an organism involved the erythrocytes of a splenectomized, previously healthy, lifelong resident of the eastern shore of Virginia. Although the organism could not be isolated in vitro, its morphology and ultrastructure suggested that it was a unique grampositive bacterium. Case Report This 49-year-old man was in his usual state of health until approximately six months before he was hospitalized. His only previous. © 1979, Massachusetts Medical Society. All rights reserved.