infections and AIDS

The earliest reports of the acquired immunodeficiency syndrome (AIDS) in homosexual men in the United States1 included a case of disseminated Mycobactenum avium-intracellulare (MAI). Since then it has become increasingly clear that opportunistic infection by mycobacteria in AIDS is a major complication of the syndrome, with serious implications for the public health of many societies, especially in Africa. The synchrony of both mycobacterial and human immunodeficiency virus (HIV) infection results in clinical presentations, complications and outcomes that are often very different from the same mycobacterial infections in those without HIV infection. There is already considerable clinical experience of combined infections and this review will discuss those reports dealing first with the non-tuberculous mycobacteria and then with tuberculosis. It concludes with a discussion of the mechanisms thought to be underlying the association of mycobacterial infections in AIDS and other immunocompromised states. NON-TUBERCULOUS MYCOBACTERIA AND AIDS Non-tuberculous mycobacteria (NTM) were only recognised as pathogens in the 1950s. They were found to be causing mostly localised pulmonary disease in middle-aged patients with pre-existing lung disease.2 Marked geographical variation was ob-served. Frequent isolation of the organisms from soil and water led to the conclusion that infection was usually environmental in origin. In a survey of mycobacterial isolates in the USA in 19793 two-thirds were M. tuberculosis. Of the NTM isolates 61 % were MAI,4 and 39 % of 636 cases of disease caused by NTM were i