From the Guidelines
Treatment of chronic Mycobacterium avium complex (MAC) infection should consist of a multidrug regimen, with a macrolide, such as clarithromycin 500mg twice daily or azithromycin 250-500mg daily, as the cornerstone medication, combined with ethambutol (15mg/kg daily) and rifabutin (300mg daily), for at least 12 months after achieving negative sputum cultures, as recommended by the most recent guidelines 1. The choice of treatment regimen should be based on the severity of the disease, the patient's immune status, and the presence of any drug-resistant strains.
- The treatment regimen should include at least two antimycobacterial drugs to prevent or delay the emergence of resistance, with clarithromycin being the preferred first agent 1.
- Ethambutol should be given at a dose of 15 mg/kg daily, and rifabutin should be used at a dose of 300 mg daily, with adjustments for interactions with antiretroviral drugs 1.
- For patients with macrolide-resistant strains, treatment regimens are far less successful, and drugs such as aminoglycosides, such as amikacin, and a quinolone, such as moxifloxicin, should be considered for inclusion 1.
- Clofazimine has been associated with excess mortality in the treatment of disseminated MAC disease and should not be used 1. Regular monitoring of the patient's response to treatment, including sputum cultures every 1-3 months, liver function tests, and visual acuity testing, is crucial to assess the effectiveness of the treatment and to detect any potential adverse effects early.
- Treatment success depends on several factors, including the extent of disease, underlying lung conditions, immune status, and medication tolerance 1.
- Surgical resection may be considered in cases with localized disease or when medical therapy fails. The treatment of MAC infection requires a long duration of therapy, typically 12-18 months after sputum culture conversion, due to the slow growth of the organisms and their natural resistance to many antibiotics, making eradication difficult without sustained antimicrobial pressure 1.
From the FDA Drug Label
Antimicrobial Activity Clarithromycin has been shown to be active against most of the isolates of the following microorganisms both in vitroand in clinical infections [see Indications and Usage (1)] ... Mycobacterium avium complex (MAC) consisting of M. avium and M intracellulare
The treatment for chronic Mycobacterium avium complex (MAC) infection is clarithromycin.
- Key points:
- Clarithromycin has been shown to be active against MAC
- The drug label does not provide a specific treatment regimen for MAC infection, but it does indicate that clarithromycin is effective against this pathogen 2
- Alternative antibacterial therapy should be considered when treating patients receiving inducers of CYP3A, as they may decrease the effectiveness of clarithromycin against MAC 2
From the Research
Treatment Options for Chronic Mycobacterium avium Complex (MAC) Infection
The treatment for chronic Mycobacterium avium complex (MAC) infection typically involves a combination of antibiotics. The following are some of the treatment options:
- A macrolide (such as clarithromycin or azithromycin) in combination with ethambutol and clofazimine 3
- Clarithromycin alone or in combination with other agents such as rifampin, aminoglycoside, quinolone, clofazimine, isoniazid, ethambutol, pyrazinamide, or minocycline 4
- A combination of at least two agents, with oral clarithromycin or azithromycin as the preferred first agent, and ethambutol as the most rational choice for the second agent 5
- Rifabutin, clarithromycin, ethambutol, sparfloxacin, and amikacin, alone or in combination, have been shown to be active against MAC in human macrophages 6
Key Drugs in the Treatment of MAC
The key drugs in the treatment of MAC include:
- Azithromycin and clarithromycin, which appear to be key drugs in the treatment of MAC 7
- Rifabutin, which has been used more often than rifampicin in studies involving patients with AIDS 7
- Ethambutol, rifampicin, and streptomycin, which are perhaps the most useful for MAC among the drugs traditionally used for M. tuberculosis (TB) 7
- Amikacin and clofazimine, which may also be useful in the treatment of MAC 7
Considerations for Effective Treatment
Effective treatment of MAC requires consideration of the following factors:
- Pharmacokinetic and pharmacodynamic considerations, including the ability of drugs to enter macrophages where the organism resides 7
- Susceptibility testing, including the use of the radiometric method (BACTEC) and the establishment of susceptibility break-points for anti-MAC agents 7
- Therapeutic drug monitoring and dosage individualization to overcome problems with drug therapy and to optimize treatment outcomes 7