Mycobacterium avium Complex (MAC)

November 2004     View PDF     En español

The bottom line

Researchers are developing and testing new drugs and drug combinations that are more effective and have fewer side effects. More novel treatment ideas and better methods of drug testing are needed.

A better understanding of how MAC bacteria function will help pave the way to finding more effective drugs to kill them. There are many questions that still need to be answered:

• What makes one strain of MAC bacteria more harmful than another?
• How does the immune response affect how the bacteria behave?
• What factors influence the bacteria becoming drug-resistant?
• What are the differences between HIV-infected and normal macrophages?
• How does HIV change the complex system of cytokines that cells of the immune system use to signal to each other?

Prevention

• Adults with CD4+ cell counts below 50 should begin preventive therapy for MAC with clarithromycin or azithromycin. Rifabutin can be used as an alternative.
• Using azithromycin avoids the risk of developing resistance to clarithromycin. Clarithromycin can then be used for treatment if MAC occurs.

Treatment

• Adults with MAC should begin treatment with clarithromycin or azithromycin + ethambutol + one or more of: rifabutin, rifampin, ciprofloxacin or amikacin.
• Clofazimine (Lamprene) should NOT be used.
• Higher doses of clarithromycin (1,000mg twice daily) have caused deaths and should NOT be used.
• Clarithromycin and rifabutin may interact with protease inhibitors. There is no interaction between azithromycin and the PIs.

Maintenance Therapy

• People who clear MAC infection should continue taking maintenance therapy for life to stop the infection from returning.
• Therapy includes clarithromycin or azithromycin plus ethambutol with or without rifabutin.