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Mycobacterium Avium-Intracellulare Medication

  • Author: Janak Koirala, MD, MPH, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
Updated: Oct 06, 2015

Medication Summary

The drugs used most often for treatment of Mycobacterium avium complex (MAC) infection include a macrolide (eg, clarithromycin, azithromycin), ethambutol, and a rifamycin (eg, rifabutin, rifampin).

Clarithromycin or azithromycin in combination with ethambutol and rifabutin are the first-choice drugs. Combination therapy is important for enhancing efficacy and preventing resistance.

Alternatively, clofazimine, streptomycin, amikacin, or a fluoroquinolone may be used as a substitute for one of the first-line agents. Streptomycin has been shown to be useful in cavitary lung disease. Amikacin is used for refractory cases.

Clofazimine should be avoided in patients with disseminated MAC (DMAC) infection because of worse outcomes compared with other regimens. The combination of a macrolide with a fluoroquinolone should be avoided, as they show antagonism in infections with some strains of MAC, and their combination has been associated with the development of resistance.

The duration of treatment is not established. In general, patients with MAC pulmonary infection should be treated for a minimum of 1 year or until 12 months after sputum stains are negative for MAC. The rate of relapse is high, especially if the treatment duration is too short. Long-term treatment, however, is harder to tolerate and increases the likelihood of adverse effects.

Macrolides are likely to interact with drugs metabolized in the liver.

Ethambutol may cause optic neuritis and blindness, especially in patients with coexisting renal dysfunction.

Rifampin and rifabutin may decrease the effectiveness of contraceptives and other drugs metabolized in the liver. Advise patients of this potential effect. Rifabutin is also known to cause uveitis, for which patients need regular eye examinations.

Failing to offer prophylaxis to patients with HIV with a CD4+ lymphocyte count of below 50 cells/µL may lead to development of DMAC infection.



Class Summary

Empiric antimicrobial therapy must be comprehensive.

Clarithromycin (Biaxin, Biaxin XL)


Clarithromycin inhibits bacterial growth, possibly by blocking dissociation of peptidyl transfer RNA (tRNA) from ribosomes, arresting RNA-dependent protein synthesis.

Azithromycin (Zithromax, Zmax)


Azithromycin inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, arresting RNA-dependent protein synthesis.

Ethambutol (Myambutol)


Ethambutol impairs cell metabolism by inhibiting synthesis of 1 or more metabolites, which in turn causes cell death. No cross-resistance has been demonstrated. Mycobacterial resistance is frequent with previous therapy. Use in these patients in combination with second-line drugs that have not been administered previously.

Rifabutin (Mycobutin)


Rifabutin is an ansamycin antibiotic derived from rifamycin S. It inhibits DNA-dependent RNA polymerase, preventing chain initiation, in susceptible bacterial strains. If GI upset occurs, administer dose twice daily with food.

Rifampin (Rifadin)


Useful in combination with other drugs, rifampin inhibits bacterial DNA-dependent RNA polymerase.

Ciprofloxacin (Cipro)


Ciprofloxacin is a fluoroquinolone that inhibits bacterial DNA synthesis and, consequently, growth, by inhibiting DNA gyrase and topoisomerases, which are required for replication, transcription, and translation of genetic material. It is used in combination with other agents in the treatment of MAC.

Levofloxacin (Levaquin)


Levofloxacin is a fluorinated quinolone that inhibits bacterial DNA gyrase and topoisomerase IV.

Moxifloxacin (Avelox)


This agent inhibits the A subunits of DNA gyrase, resulting in inhibition of bacterial DNA replication and transcription.



Amikacin irreversibly binds to the 30S subunit of bacterial ribosomes, blocks the recognition step in protein synthesis, and causes growth inhibition. Use the patient's ideal body weight (IBW) for dosage calculation.



Streptomycin acts by binding to the 30S ribosomal subunit and interferes with translational proofreading, which result in an inhibition of protein synthesis. It is used in combination with other drugs in the treatment of MAC.

Clofazimine (Lamprene)


Clofazimine is a lipophilic rhimophenazine dye that inhibits template function of DNA by binding to it. It is weakly bactericidal and has anti-inflammatory effects. This agent was originally developed to treat tuberculosis. Although its mechanism of action is unclear, it seems to exert its main effect upon neutrophils and monocytes in a variety of ways (eg, stimulating phagocytosis and release of lysosomal enzymes).

Clofazimine is absorbed orally, accumulates in tissues, and has half-life >70 d. In addition to daily dose, loading dose of 300 mg once a month (under supervision) is given in leprosy control programs. This approach maintains optimal amount of drug in body tissue, even if the patient occasionally misses daily dose.

This agent was discontinued from the United States market in 2005, but is now available as orphan product.

Contributor Information and Disclosures

Janak Koirala, MD, MPH, FACP, FIDSA Professor and Division Chair, Division of Infectious Diseases, Department of Internal Medicine, Southern Illinois University School of Medicine

Janak Koirala, MD, MPH, FACP, FIDSA is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians-American Society of Internal Medicine, American Society for Microbiology, International AIDS Society, International Society for Infectious Diseases, International Society of Travel Medicine, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Aaron Glatt, MD Chief Administrative Officer, Executive Vice President, Mercy Medical Center, Catholic Health Services of Long Island

Aaron Glatt, MD is a member of the following medical societies: American College of Chest Physicians, American Association for Physician Leadership, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Association, American Society for Microbiology, American Thoracic Society, American Venereal Disease Association, Infectious Diseases Society of America, International AIDS Society, Society for Healthcare Epidemiology of America

Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD David Ross Boyd Professor and Chairman, Department of Medicine, Stewart G Wolf Endowed Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center; Master of the American College of Physicians; Fellow, Infectious Diseases Society of America

Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American Medical Association, Oklahoma State Medical Association, Southern Society for Clinical Investigation, Association of Professors of Medicine, American College of Physicians, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Additional Contributors

Klaus-Dieter Lessnau, MD, FCCP Clinical Associate Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory; Director of Research in Pulmonary Medicine, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital

Klaus-Dieter Lessnau, MD, FCCP is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Medical Association, American Thoracic Society, Society of Critical Care Medicine

Disclosure: Nothing to disclose.


The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous author William B Harley, MD,to the development and writing of the source article.

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CT thorax of a 77-year-old woman who presented with chronic cough and sputum production, without a history of underlying pre-existing lung disease. Sputum culture grew Mycobacterium avium complex. The diagnosis was Lady Windermere syndrome.
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