Mycobacterium avium complex infection

Related Key Words and Synonyms:

Epidemiology and Demographics
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.

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

Pathophysiology & Etiology
Etiologic Agent:

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

Transmission:

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

Diagnosis
Diagnosis can be achieved through blood cultures, or cultures of other bodily fluids such as lymphatic dranage or stool. Bone marrow culture can often yield an earlier diagnosis, but is usually avoided as an initial diagnostic step because of its invasiveness.

History and Symptoms
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.

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

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

Pharmacotherapy
Treatment involves a combination of anti-tuberculosis antibiotics. These include:


 * Rifampicin
 * Rifabutin
 * Ciprofloxacin
 * Amikacin
 * Ethambutol
 * Streptomycin
 * Clarithromycin
 * Azithromycin

Acknowledgements
The content on this page was first contributed by: C. Michael Gibson, M.S., M.D.