Mycobacterium avium-intracellulare infection during HIV disease. Persisting problems

Still in the era of combined antiretroviral therapy, late recognition of HIV disease or lack of sufficient immune recovery pose HIV-infected patients at risk to develop opportunistic infections by nontuberculous mycobacteria (NTM), which are environmental organisms commonly retrieved in soil and superficial waters.Among these microorganisms, the most frequent is represented by Mycobacterium avium complex (MAC). Health care professionals who face HIV-infected patients should suspect disseminated mycobacterial disease when a deep immunodeficiency is present, (a CD4+ lymphocyte count below 50 cells/μL) often associated with constitutional signs and symptoms, and non-specific laboratory abnormalities. Mycobacterial culture of peripheral blood is a reliable technique for diagnosing disseminated disease. Among drugs active against NTM, as well as some anti-tubercular compounds, the rifampin derivative rifabutin, and some novel fluoroquinolones, the availability of macrolides, has greatly contributed to improve both prophylaxis and treatment outcome of disseminated MAC infections. Although multiple questions remain about which regimens may be regarded as optimal, general recommendations can be expressed on the ground of existing evidences.Treatment should begin with associated clarithromycin (or azithromycin), plus ethambutol and rifabutin (with the rifabutin dose depending on other concomitant medications that might result in drug-drug interactions).A combined three-drug regimen is preferred for patients who cannot be prescribed an effective antiretroviral regimen immediately. Patients with a CD4+ lymphocyte count below 50 cells/μL, who do not have clinical evidence of active mycobacterial disease, should receive a primary prophylaxis with either clarithromycin or azithromycin, with or without rifabutin.