Mycobacterium avium Complex

• Mycobacterium avium Complex

Clinical Features

Several different syndromes are caused by Mycobacterium avium complex (MAC). Disseminated infections are usually associated with HIV infection. Less commonly, pulmonary disease in nonimmunocompromised persons is a result of infection with MAC. In children, the most common syndrome is cervical lymphadenitis.

Etiologic Agent

Mycobacterium avium complex (comprising M. avium and M.intracellulare).

Incidence

Not reportable. Population-based data available for Houston and Atlanta metropolitan areas suggest a rate of 1/100,000/year. Incidence is decreasing among HIV- infected patients as a result of new treatment modalities e.g., combination therapy with nucleoside reverse transcriptase inhibitors and protease inhibitors, as well as antimycobacterial prophylaxis.

Sequelae

In HIV infected persons, manifestations include night sweats, weight loss, abdominal pain, fatigue, diarrhea, and anemia.

Transmission

Although the mode of transmission is unclear, MAC is most likely environmentally acquired.

Risk Groups

HIV-infected persons. Rarely in children or nonimmuno-compromised persons.

Surveillance

MAC is not nationally reportable. Currently under active surveillance in the Houston and Atlanta metropolitan areas.

Trends

Incidence is decreasing because of changes in treatment for HIV-infected patients; however, antimicrobial resistance may be increasing.

Challenges

Antimicrobial resistance and better treatment for affected persons. Unclear knowledge of acquisition of MAC from the environment.

Opportunities

Reduction in MAC infection as a significant cause of morbidity and mortality in HIV-infected patients as a result of changes in available therapies.