Non-tuberculous mycobacteria are major opportunistic pathogens of HIV-infected children and adults who have severe immunosuppression. Mycobacterium avium is the predominant pathogen, typically causing systemic infection (referred to as disseminated M. avium complex infection or DMAC). With the advent of highly active antiretroviral therapy (HAART) and the resulting improved preservation of immune competence, DMAC infection has become less common [1]. Among HIV-infected children with advanced disease, however, DMAC infection remains an important cause of morbidity and mortality, so that prevention and management of non-tuberculous mycobacterial infection are important aspects of the care of children with AIDS. With increasing resistance to all classes of antiretroviral drugs over time, and intolerance or poor adherence to therapy, the potential for increased incidence of DMAC infection in HIV-infected children remains a threat.

Epidemiology

Mycobacterium avium and many of the other non-tuberculous mycobacteria are widely distributed in the environment. They are found in water and soil in nature and have been identified in food and in institutional water systems [2, 3]. These organisms are uncommon causes of infection in normal hosts, and thus are opportunistic pathogens in patients with depressed cell-mediated immunity, including those with HIV infection.

While DMAC infection is a major opportunistic infection in North America and Western Europe, it is uncommonly identified in persons with AIDS in Africa or other less-developed areas of the world. It is not known whether this difference reflects differences in distribution of pathogenic strains of MAC in the environment.