Treatment Duration for Mycobacterium Avium Complex (MAC) with Azithromycin and Rifampin
For MAC pulmonary disease, treatment with azithromycin and rifampin (plus ethambutol) should be continued until sputum cultures are negative for 12 months while on therapy. 1
Treatment Regimens Based on Disease Type
Nodular/Bronchiectatic MAC Disease
- For most patients with nodular/bronchiectatic MAC disease, a three-times-weekly regimen is recommended:
- Azithromycin 500 mg three times weekly
- Rifampin 600 mg three times weekly
- Ethambutol 25 mg/kg three times weekly 1
Fibrocavitary or Severe Nodular/Bronchiectatic MAC Disease
- For patients with fibrocavitary or severe disease, a daily regimen is recommended:
- Azithromycin 250 mg daily
- Rifampin 600 mg daily (10 mg/kg/day, maximum 600 mg)
- Ethambutol 15 mg/kg daily 1
- Consider adding amikacin or streptomycin three times weekly early in therapy for severe disease 1
Treatment Duration and Monitoring
- The primary microbiologic goal is 12 months of negative sputum cultures while on therapy 1
- Monthly sputum cultures should be obtained to monitor treatment response 1
- Patients should show clinical improvement within 3-6 months of starting therapy 1
- Sputum conversion to negative should occur within 12 months on macrolide-containing regimens 1
- Treatment should continue until sputum cultures remain negative for 12 consecutive months 1
Treatment Efficacy and Considerations
- Studies have shown similar efficacy between daily and three-times-weekly regimens for nodular/bronchiectatic disease, with culture conversion rates of 55-78% 2, 3
- Three-times-weekly regimens are generally better tolerated than daily regimens, with fewer adverse events leading to medication discontinuation 1
- Recent data suggests azithromycin-based regimens are less likely to be changed or discontinued than clarithromycin-based regimens 4
- Similarly, rifampin-containing regimens are better tolerated than rifabutin-containing regimens 4
Important Cautions and Considerations
- Intermittent (three-times-weekly) therapy is not recommended for:
- Patients with cavitary disease
- Patients who have been previously treated
- Patients with moderate or severe disease 1
- Never use macrolide monotherapy due to risk of developing macrolide resistance 1
- A macrolide with only ethambutol (two-drug regimen) may be adequate for nodular/bronchiectatic disease but should not be used for fibrocavitary disease due to risk of macrolide resistance 1
- For disseminated MAC disease (such as in AIDS patients), treatment should continue indefinitely unless immune function is restored 1
Treatment Failure Considerations
- If patients fail to respond within 3-6 months or fail to convert sputum within 12 months, investigate:
- Medication non-compliance
- Development of macrolide resistance
- Anatomic limitations (focal cystic or cavitary disease) 1
- Expert consultation should be sought for patients who have difficulty tolerating MAC treatment regimens or who do not respond to therapy 1