Disseminated Mycobacterium avium complex disease in patients with AIDS

Disseminated Mycobacterium avium complex (MAC) infection is a common complication of advanced HIV disease that is associated with significant morbidity. After diagnosis of MAC by recovery of organisms from blood or other normally sterile sites, specific treatment with multiple-drug regimens is appropriate and may reduce morbidity. Multiple-drug regimens with agents active against MAC should be employed to reduce the development of drug resistance. Unfortunately, as most clinical trials of anti-MAC agents have lasted 12 weeks or less and have not compared specific agents, the most effective multiple-drug regimen has not been established. The U.S. Public Health Service Task Force on Prophylaxis and Therapy of MAC recommends treatment of disseminated disease with at least two antimycobacterial agents, one of which should be clarithromycin or possibly azithromycin. Ethambutol, which may have an additive or synergistic effect in combination with other anti-MAC agents, is a reasonable second drug. Other agents with activity include rifampin or rifabutin, clofazimine, ciprofloxacin, or parenteral amikacin. A microbiological response may require up to 2 to 8 weeks. The clinical response generally parallels the microbiological response. Rifabutin, which is licensed for prophylaxis of MAC, reduces the incidence of and delays the time to MAC bacteremia. Individuals at highest risk of MAC bacteremia (i.e., CD4+ cell counts of < 75-100 cells/microliters) had the most benefit from rifabutin prophylaxis. Tuberculosis must be ruled out before rifabutin prophylaxis is initiated. Careful observation without prophylaxis is an acceptable alternative for those who are not able to take rifabutin or alternative agents.