From the Guidelines
The recommended treatment regimen for Nontuberculous Mycobacteria (NTM) infections, specifically those caused by Mycobacterium avium complex (MAC), typically involves a multidrug approach with a macrolide as the cornerstone, including clarithromycin or azithromycin, rifampin or rifabutin, and ethambutol, with treatment continuing for at least 12 months after culture conversion. This approach is based on the most recent and highest quality study available, which emphasizes the importance of a multidrug regimen to prevent the development of resistance and effectively eradicate the infection 1.
Key Components of Treatment
- A macrolide, such as clarithromycin (500 mg twice daily) or azithromycin (500 mg three times weekly), is the cornerstone of treatment.
- Rifampin (600 mg daily) or rifabutin (300 mg daily) is added to the regimen.
- Ethambutol (15 mg/kg daily) is also included in the standard regimen.
- For cavitary or severe nodular/bronchiectatic disease, an injectable aminoglycoside like amikacin may be added initially.
Duration and Monitoring of Treatment
- Treatment should continue for at least 12 months after culture conversion, typically resulting in 18-24 months of total therapy.
- Medication adjustments may be necessary based on drug susceptibility testing, particularly if macrolide resistance is present.
- Regular monitoring through sputum cultures every 1-3 months, liver function tests, and visual acuity testing is essential to ensure treatment success and minimize side effects.
Side Effects and Considerations
- Common side effects include gastrointestinal disturbances, liver enzyme elevations, and vision changes with ethambutol.
- Ethambutol ocular toxicity may present with blurred vision, decreased acuity, central scotomas, impaired red-green color discrimination, and peripheral visual field defects, necessitating regular visual acuity and color vision testing.
- Patients should be educated about the potential side effects of ethambutol and encouraged to self-report changes in vision.
Special Considerations in Cystic Fibrosis
- Individuals with cystic fibrosis (CF) who have MAC infection should be managed in collaboration with experts in the treatment of NTM and CF.
- The treatment regimen for MAC in CF patients should be tailored to the individual's specific needs and may involve adjustments to the standard regimen based on drug susceptibility testing and the presence of other CF pathogens or comorbidities.
From the Research
Nontuberculous Mycobacteria (NTM) Treatment Regimen
The recommended treatment regimen for NTM infections, specifically those caused by Mycobacterium avium complex (MAC), typically involves a combination of antibiotics.
- A macrolide-containing three-drug regimen is recommended over a two-drug regimen as a standard treatment, with azithromycin preferred over clarithromycin 2.
- The treatment regimen often includes rifabutin (or rifampin) and ethambutol as companion drugs, as well as initial streptomycin 3.
- Treatment duration for MAC-PD is recommended to be at least one year after culture conversion 2.
Alternative Treatment Options
For patients who cannot maintain standard treatment, alternative options have been studied, including:
- Concomitant use of aminoglycoside, amikacin liposomal inhalation, clofazimine, linezolid, bedaquiline, and fluoroquinolone with modification of guideline-based therapy 2.
- Intermittent azithromycin and ethambutol therapy for noncavitary MAC-PD, which may be an optional treatment regimen 4.
Treatment Challenges
NTM treatment is often longer than TB treatment, more likely to fail, and more likely to cause toxicity 5.
- The recurrence rate of MAC-PD can be as high as 25-45%, with a significant percentage of recurrences due to reinfection with a new genotype from the environment 2.
- Macrolide resistance is a significant concern, and patients with macrolide-resistant MAC isolates are much harder to treat and have higher mortality 6.