Definition of Mycobacterium avium complex

Mycobacterium avium complex: Abbreviated MAC. An opportunistic infection caused by two similar slow-growing bacteria called Mycobacterium avium and Mycobacterium intercellulare that are found in the soil and in dust particles. Disseminated MAC infections are usually associated with immunocompromise, as in AIDS. Less commonly, pulmonary disease in nonimmunocompromised persons is the result of infection with MAC. In children, the most common syndrome of MAC is cervical lymphadenitis (swollen glands in the neck).

In a person with AIDS or another type of immunoideficiency, MAC can spread through the bloodstream to infect lymph nodes, bone marrow, liver, spleen, spinal fluid, lungs and intestinal tract. Typical symptoms of MAC include night sweats, weight loss, fever, fatigue, diarrhea and enlarged spleen. MAC is usually found in people with CD4 counts below 100.

Clarithromycin, azithromycin, ethambutol, rifampin, clofazimine and rifabutin are some of the antibiotics commonly used in MAC prevention and treatment.