[Treatment and prevention of Mycobacterium avium complex infection in AIDS]

Since Mycobacterium avium complex (MAC) infects most, if not all, HIV-positive patients, effective regimens for its treatment and prophylaxis are a necessity. We review here the available literature in an attempt to establish clear-cut criteria for the administration of antibiotics and immunotherapy and for the prophylactic treatment of MAC infections. Several antibiotics, chiefly in combination regimens, are active against MAC. Recent data indicate rifabutin as a first-line antibiotic for the treatment of MAC infections. However, since this antibiotic accelerates hepatic metabolism of many drugs (zidovudine in particular), it has the potential to reduce their serum concentrations and hence limit their antiviral activity. Moreover, rifabutin is active against retroviruses only at extremely high concentrations which are not reached in vivo at normally-prescribed dosages. The recent demonstration that the cytokine interferon-gamma (IFN-gamma) in combination with conventional antibiotic therapy may be effective for disseminated MAC infections indicates that immunotherapy could play a pivotal role in the treatment of MAC infections. Lifetime prophylaxis with rifabutin (300 mg/die) is advised for all patients with HIV infection and fewer than 100 CD4 T lymphocytes/mm3 in the peripheral blood: this antibiotic regimen significantly reduces the frequency of disseminated MAC infections. Further studies are required to evaluate the effectiveness of other prophylactic regimens such as azithromycin and clarithromycin. We conclude that rifabutin and immunotherapy with IFN-gamma will play a key role in the treatment of MAC infections.