Fatal Infection with a Novel, Unidentified Mycobacterium in a Man with the Acquired Immunodeficiency Syndrome

MYCOBACTERIUM tuberculosis and Mycobacterium avium–intracellulare are among the common pathogens that infect patients with the acquired immunodeficiency syndrome (AIDS).1 2 3 In this report, we describe a patient seropositive for the human immunodeficiency virus (HIV) whose disease clinically resembled infection with M. avium–intracellulare. Numerous acid-fast rods were found in nearly all the tissues we examined, but the cultures remained negative. Nucleic acid analyses were negative for M. tuberculosis, the M. avium complex, and M. leprae, but electron microscopy and lipid analysis by chromatography suggested that the pathogen was a mycobacterium. The microorganism multiplied in congenitally athymic nude mice. Its species remains . . .