Mycobacterium Avium Complex Infection

GENERAL PRINCIPLES

MAC infection is the most commonly occurring mycobacterial infection in AIDS patients and is responsible for significant morbidity in patients with advanced disease (CD4 cell count lt;50 cells#8725;#956;L).

DIAGNOSIS

Clinical Presentation

• Disseminated infection with fever, weight loss, night sweats, and GI complaints is the most frequent presentation.

• MAC infection can result in bacteremia in AIDS patients.

Diagnostic Testing

• Anemia and an elevated alkaline phosphatase level are the usual laboratory abnormalities.

• Mycobacterial blood cultures should be sent in suspected cases.

TREATMENT

• Initial therapy should include a macrolide (i.e., clarithromycin, 500 mg PO bid) and ethambutol, 15 mg/kg PO daily.

• Rifabutin, 300 mg PO daily, an aminoglycoside 10-15 mg/kg IV daily, or a fluoroquinolone can be added in severe cases or patients not on effective ART, and based on susceptibilities.

• Utility of disseminated MAC prophylaxis was recently under debate given prophylaxis toxicity and effectiveness of modern ART; however currently both the US Department of Health and Human Services and the International Antiviral Society of USA recommend against primary prophylaxis if effective ART is initiated immediately and viral suppression achieved (AIIa recommendation). Primary prophylaxis is only currently recommended if patients are not receiving ART and CD4 counts lt;50 cells/mm³.

• Secondary prophylaxis for disseminated MAC can be discontinued if the CD4 count has a sustained increase of gt;100 cells#8725;#956;L for 6 months or longer in response to ART, and if 12 months of therapy for MAC is completed and there are no symptoms or signs attributable to MAC.