Treatment of MAC requires a multidrug regimen as MAC is resistant to most ordinary antibiotics. Use of only one or two drugs may result in the development of mutations in the MAC so they become resistant to the drugs.
Standard treatment of MAC recommended by the American Thoracic Society (ATS) is a combination of 3 or 4 drugs approved by the Food and Drug Administration (FDA). The drugs include:
Clarithromycin (Biaxin) or Azithromycin (Zithromax)
Rifampin (Rifadin) or Rifabutin (Mycobutin) + Ethambutol (Myambutol)
Streptomycin (Strep) or Amikacin (Amikin)
The first three drugs are pills/capsules and may be given daily or three times weekly (Monday-Wednesday-Friday). While taking these medicines, routine laboratory tests to check kidneys and liver along with a complete blood count (CBC) should be performed, at least routinely for the first six months. Patients who fail therapy after taking the 3 standard medicines (clarithromycin/azithromycin, rifampin/rifabutin, and ethambutol) are usually required to take additional medicines (such as injectables or “shots”) which may be effective. For extensive or severe disease, or disease that has failed therapy, the injectables streptomycin or amikacin are often added for the first 2 to 4 months of therapy.
Amikacin has recently become available in an inhaled form which causes less toxicity than IV or IM administration.