1. A common
opportunistic infection caused by two very similar mycobacterial organisms,
Mycobacterium avium and
Mycobacterium intracellulare. 2. A bacterial
infection that can be localized (limited to a specific organ or area of the body) or
disseminated throughout the body. It is a life-threatening disease, although new therapies offer promise for both prevention and treatment. MAC disease is extremely rare in people who are not infected with HIV. See also
Opportunistic Infection.