About “Mycobacterium avium intracellulare complex (MAC)
From a Patient’s Perspective

Q: What is MAC?
A: “Mycobacterium avium intracellulare” (MAI) or “Mycobacterium avium Complex” (MAC) is an atypical NON-TB germ (micro-organism). MAC is related to the tuberculosis germ, but is not contagious and the MAC microbes live in the environment. It comprises more than one type of microorganism (both M. avium and M. intracellulare). It causes two types of lung disease. One type results in multiple nodules in the lungs and is referred to as “nodular disease”. The second type is associated with cavities in the upper parts of the lung that mimic tuberculosis. This type of disease is referred to as “upper lobe cavitary disease”.

Q: Why do people get MAC infection?

A: There are no known causes but several factors that contribute to pulmonary MAC disease. Some documentation includes the relationship of pulmonary MAC to scoliosis (curvature of the spine), gastroesophageal reflux disease (GERD), asthma and chronic bronchitis. There is evidence that the disease is environmentally acquired meaning that the MAC germs get into the lungs or body via air, water, or soil. MAC is also acquired in conjunction with other underlying diseases such as Cystic Fibrosis, lung issues caused by heavy smoking, excessive alcohol consumption, and Acquired Immune Deficiency Syndrome (AIDS).

1. For patients with NB MAC lung disease, the priorities are typically to treat the underlying bronchiectasis and determine the course and impact of the MAC infection over time. Guidelines-based MAC therapy with multidrug regimens including macrolides is usually effective, but far from as predictably effective and durable as therapy for tuberculosis.
2. MAC is treated with a combination of antibiotics that should include at least two drugs, usually clarithromycin or azithromycin, plus ethambutol. Other antibiotics may be added depending on the severity of the case. Unfortunately, all of the drugs used to treat MAC can cause serious side effects that may require treatment with yet other drugs.
3. Apr 27, 2013 If you type in 'MAC lung disease forum', you'll get to the site - it's the one connected to the Tyler, Texas facility - If your infection is not extensive and your doctor has advised monitoring rather than medication, I would think it would be fine to adopt those alternative 'treatments' - however, if your situation is more advanced, I don't see that those would be preferable to medication.

Disseminated MAC disease frequently occurs in AIDS patients due to a very low immune system but is a different type of disease than chronic lung MAC. The MAC disease in AIDS is widely disseminated throughout the body and rarely involves the lung, while pulmonary MAC only involves the lungs.

MAC pulmonary (lung) disease’ major susceptibility risk factors depend on which of the two types of disease are present. For nodular disease the risk factors are being Caucasian, female, average age between 60 and 70, and having bronchiectasis. The most important relationship in women is that of bronchiectasis. For patients with MAC upper lobe cavitary disease, the major risk factors are being male, average ages between 50-60, heavy smoking, and often-excessive alcohol consumption.

Q: What is bronchiectasis?

A: Bronchiectasis derives its meaning from the combination of the terms “bronchus” (breathing tube) and “ectasia” (dilation). Bronchiectasis is chronic dilatation of the breathing tubes causing secondary infection usually in the lower portion of the lungs. Bronchiectasis is considered to be incurable permanent damage to the affected areas of the lungs. It is associated with excessive mucous production that results in coughing and small to copious amounts of sputum. The excess mucous is produced and the lungs of patients with bronchiectasis do not adequately clear airways via cilia (small hairs similar to brushes that line the breathing tubes). The mucous builds up and causes stagnated sputum that invites infections. Bronchiectasis is associated with the development of chronic infection of bacteria known as Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), as well as MAC and Mycobacterium abscessus.

Q: What kind of medications will help for MAC lung infection and for how long should these medicines be continued?

MAC disease is very difficult to cure because it is hard for the medicines to reach the inside of the nodule or cavity. The usual length of treatment lasts for at least 15 to 18 months. In other words, a MAC patient should keep taking the medications for the prescribed length of.

A: The current treatment of choice for new patients with either of the two types of lung disease due to MAC is a three-drug regimen of pills. The medications are clarithromycin (Biaxin, made by Abbott Pharmaceuticals) or azithromax (Zithromax, made by Pfizer), (both belong to a chemical class of drugs called macrolides); ethambutol (Myambutol, Barr Pharmaceuticals); and rifabutin (Mycobutin, Pfizer); or rifampin (Rifadin, produced by Aventis Pharmaceuticals). For patients with advanced or severe disease a fourth drug is given as an intramuscular shot, intravenous infusion, or inhalation (Arikayce, Insmed Incorp.). This drug is either amikacin (Amikin, by Sicor Pharmaceuticals) or Streptomycin (X-Gen Pharmaceuticals). Other drug companies sometimes produce the generic forms of the medicines.

MAC disease is very difficult to cure because it is hard for the medicines to reach the inside of the nodule or cavity. The usual length of treatment lasts for at least 15 to 18 months. In other words, a MAC patient should keep taking the medications for the prescribed length of time in order for the germs to be eliminated. If “super-bugs” (drug resistant germs) develop, then cultures would be taken and medications adjusted for efficacy and susceptibility of the ‘bugs’ to other antibiotic treatments. Current recommendations are to take the oral medicines until the sputum cultures do not grow the MAC for 12 months based on monthly sputum tests. The shots or infusions are generally given only for the first 2-4 months.

Other medicines may be used in patients who have failed therapy with these drugs or who cannot tolerate them. These medicines include inhaled amikacin (via a nebulizer), ciprofloxacin (Cipro), rifabutin (for patients who were on rifampin), mefloquin (Larium, a malaria drug), clofazimine (Lamprene, a leprosy drug), ethionamide, and cycloserine. Few to no clinical studies have been completed to see if these drugs work for MAC. Ethionamide and cycloserine are rarely used because of their toxicity and the need for the latter to be closing monitored via blood levels. Health care personnel experienced in treating MAC should prescribe these medicines.

Q: Is there a cure for MAC?

A: There is the possibility that MAC may be cured or at least arrested if the treatment plan is carefully followed. The cure rate is greater than 90% if sputum cultures are negative for 12 months while on the medications. For patients with underlying bronchiectasis, there is the chance of getting a second infection with a new MAC bug. (There are many different variations of MAC.) There is NO cure, however, for the underlying bronchiectasis.

Q: How do patients with MAC lung present?

A: Patients with bronchiectasis as their risk factor usually present with chronic coughing and some amount of sputum. Sometimes the sputum is yellowish, greenish, or bloody, but most often is whitish to clear. Chest films sometimes appear abnormal noting adhesions or nodules. The patient will frequently report a history of repeated bouts of bronchitis, pneumonias, shortness of breath, and chest congestion. Patients also complain of mild, moderate, or even severe chronic fatigue and inability to participate in activities of daily living. Sometimes the symptoms of bronchiectasis are much more subtle and fatigue is the only significant complaint. Some patients are not accurately diagnosed until the MAC is quite active or until accidentally seen via a chest film or CT scan that shows pulmonary adhesions, infiltrates, or nodular activity. There may already be bilateral nodular activity and bronchiectasis commonly in the right middle lobe at the time of diagnosis. Other symptoms of illness in MAC patients with nodular lung infections are low-grade fever, night sweats, loss of appetite (“I never get hungry), and mild weight loss. Complete blood counts (CBC’s) and complete metabolic panels (CMP’s) may be abnormal. Low red blood cell counts (anemia) are quite common.

Patients with heavy smoking as their risk factor who develop cavitary lung disease usually have more pronounced symptoms of bloody sputum, copious amounts of colored sputum, and heavy, productive coughing and significant weight loss (> 10 pounds). Both nodular and cavitary lung disease patients may experience acute illness that mimics pneumonia with fever, chills, bodily aches, pains, and shortness of breath.

FATIGUE is a common complaint of MAC patients with bronchiectasis. The fatigue symptoms may vary from mild to severe and interfere with every aspect of life. MAC patients must learn to cope with the fatigue and continue to take part in activities to maintain quality of life even though the fatigue is a continuing factor. Sometimes there must be lifestyle changes and dramatically altered daily routines. Patients may discover that rest periods, daily exercising, and healthy diets with adequate caloric intake will contribute to decreasing the fatigue thus increasing quality of life.

Q:Can bronchiectasis be cured?

A: Bronchiectasis is a chronic, incurable condition that causes permanent damage due to enlargement (dilatation) of the breathing tubes. The bronchioles expand into the lobes causing displacement and ineffective clearing of mucous from the lungs and bronchial tubes. The damaged breathing tubes also produce mucous that can cause stasis or pooling of old mucous and encourage infection.

The MAC may be cured but NOT the bronchiectasis. The bronchiectasis causes patients to be susceptible to other bugs such as Pseudomonas, Staphylococcus, Klebsiella, and other bacteria. The other most commonly isolated mycobacteria include Mycobacterium abscessus, andMycobacterium kansasii. The importance of periodic or routine sputum cultures cannot be overemphasized with a diagnosis of bronchiectasis. Sputum samples are the best source of keeping track of the disease and progression of treatment, especially while being treated for MAC.

Q: Will the disease cause an early death?

A: MAC treatment may possibly “cure” the MAC infection. However, the damage already done to the lungs cannot be cured (bronchiectasis). The breathing tests (also called pulmonary function tests) are abnormal in most patients with bronchiectasis. MAC patients with bronchiectasis are susceptible to lung and breathing problems for a lifetime. Physicians who specialize in MAC and/or bronchiectasis are expected to provide patients with updated information, treatment modalities, and follow up visits. Life does not necessarily have to be cut short by MAC. One may die WITH MAC but not necessarily because OF MAC. The patient must be compliant with the treatment recommendations. Trust between the physician and patient is tremendously important since the treatment plan is lengthy and normally quite arduous.

Q: Will the disease decrease quality of life?

A: Although MAC may be “cured”, the disease of bronchiectasis does not result in total symptom-free living. Patients who are unable to cure their MAC may have to deal with residual effects of both diseases (i.e., MAC and bronchiectasis). This often will decrease the quality of life compared to “before MAC”.

The patients must pay attention to symptoms, take medications indefinitely, exercise regularly, and provide good nourishment to maintain a healthy weight. It is essential to envelope rigorous pulmonary hygiene, providing sputum cultures or getting bronchoscopes as needed. It is also important to avoid exposure to known infections, rest periodically as needed, and promote good sleep patterns. It is possible to maintain a good quality of life by following these suggestions.

Q: Is MAC contagious?

1. This is usually a real concern for patients due to family expectations and responsibilities for others. MAC is not considered to be contagiousfrom human to human. It is thought that MAC is acquired by exposure to soil, air, or water. People who are affected are usually those with low immune systems (patients with AIDS), or those suffering from chronic lung conditions (bronchiectasis, heavy smoking, or cystic fibrosis). Patients without these factors are not at risk for contracting MAC.

Q: What is considered a good treatment plan?

1. Patients are wise to practice compliance with the prescribed medications, report any side effects, take part in daily exercise, and follow proper nutritional guidelines. It is mandatory to practice daily pulmonary hygiene. Pulmonary hygiene is the art of loosening secretions (mucous), coughing up the excess sputum, and thus clearing it from the lungs. Excessive mucous within the lungs may contribute to infection, causing bronchitis and/or pneumonia, and progressive MAC disease and bronchiectasis. It also contributes to the feeling of chest tightness and congestion.

Q: Are there alternative treatments in addition to the oral medications?

A: There are antibiotics introduced by intramuscular injection or infusion therapy via use of peripherally inserted central catheters (also called PICC lines). These medicines include amikacin and streptomycin.

Inhaled antibiotics such as amikacin are also available

Surgery to remove portions of the damaged lung is occasionally recommended. This is especially true for patients with disease in just one part of the lung who have failed therapy or whose MAC has become resistant to clarithromycin and azithromycin.

Q: How do I know when I need to try other treatments?

A: MAC lung patients are initially treated for 15-18 months. Monthly follow up visits are recommended that include blood work and sputum samples. Less frequent testing is done via CT scans, chest films, and pulmonary function studies about every 6 months. Bronchoscopy may be required for those patients unable to produce sputum samples for culture (a common problem among the women with nodular disease and bronchiectasis).

Patients whose sputum remains culture positive for MAC after 12 months of drug treatment are considered treatment failures. Patients whose sputum cultures become negative for MAC almost always do so within 6 months of starting their drugs. If the condition worsens with symptoms or if the tests appear to change, then the physician would need to re-evaluate the treatment plan and possibly consider another regimen of antibiotic therapy.

Q: How long do I have to be medicated?

A: The initial treatment usually lasts from 15-18 months. However, if the cultures remain positive or the MAC condition worsens, then the length of therapy will most likely be increased. Treatment continues until monthly sputum cultures are completely negative (no MAC) for one year. It is possible that a MAC patient may need to remain on antibiotic therapy indefinitely.

Q: Why is there a need for long-term medication therapy?

A: The response to antibiotic therapy, unlike bacterial infections, is very slow. MAC causes nodular activity in the lungs. The nodules are round and impacted and can cause antibiotics to work ineffectively. There is also a chance that the germs can become “resistant” to antibiotics, thereby rendering antibiotics useless and ineffective. Monthly sputum samples must be collected for culture in order to receive effective treatment. Testing for susceptibility of the MAC to clarithromycin or azithromycin in the laboratory (called drug susceptibility testing) should be performed every four to six months while on drug treatment. The medication regimen must be changed to different antibiotics if the germs are no longer “susceptible” to the clarithromycin.

Q: What are the expectations related to progression of MAC?

A: MAC may occasionally cause absolutely no symptoms or illness. It may be diagnosed before or after it has caused damage to the lungs. MAC may progress by nodular growth and chronic infection. There is no known explanation or rationale for these phenomena. Each MAC case may vary tremendously in terms of symptoms and computerized tomography (CT) scan findings. Most patients with MAC and bronchiectasis are followed indefinitely with CT scans and sputum cultures. Without drug therapy, cavitary disease often progresses to additional lung involvement within a few months, while nodular disease may progress more slowly. This may cause worsening of cough and fatigue, and more shortness of breath. The disease does not progress and clinically improves with appropriate drug therapy as evidenced by X-rays or CT scans.

Q: What are the requirements for blood work, check ups, and diagnostic testing?

A: Baseline tests are performed upon initiation of medication therapy. Diagnostic check-ups are then recommended on a regular basis every 4-6 weeks while on medications. The monthly safety tests include blood counts, liver and kidney function tests, and sputum cultures. Physician follow up visits consist of questions about the potential development of side effects such as blurry vision (caused by ethambutol), nausea and vomiting, or diarrhea (Biaxin or Zithromax), or fever and chills (rifabutin). The questioning about blurry vision while on ethambutol is especially important because the drug must be promptly discontinued if the vision change appears to relate to the medicine. Additional testing for eyes are use of the “eye chart” with letters read at 20 feet, and a red-green color book to distinguish changes in the ability to visualize colors. HRCT (high resolution computerized tomography) scans, and pulmonary function tests are completed at the start of therapy and continued on an as needed basis.

Q: What are suggested comfort measures for MAC patients?

A: Regular daily exercise including walking, Yoga, Pilates, and strength training is highly recommended. MAC patients must remember that effort is required to maintain exercise due to chronic and sometimes extreme fatigue. It is very easy to become tired and not feel up to exercising. However, the continued plan will eventually contribute to improving daily quality of life.

Proper nutrition and adequate caloric intake to prevent weight loss and even encourage weight gain is helpful for MAC patients. Regular rest periods and sleep patterns assist to lessen fatigue. There may be some benefit for regular counseling visits and taking prescribed medications for depression and anxiety due to the stress of chronic illness. MAC patients can help themselves by maintaining a proactive stance and keeping up to date regarding current knowledge about the disease.

A monumental issue with MAC disease is fatigue or tiredness. Women may not be able to cook, maintain a job, or clean house on a regular basis. Therefore routines may need to be altered and assistance with activities of daily living may be required. Enlistment of others’ help and support is essential.

Joining a MAC support group may be helpful, encouraging, and promote a core sense of understanding of MAC disease. The support group can provide an excellent knowledge base and therapeutic environment for its members. Details are provided elsewhere for joining such a support group. Consent forms must be signed in the physician’s office before becoming a member of the support group.

Q: How do family relationships realistically continue?

A: MAC patients need to listen to their own body for direction. Patients may benefit from open and honest discussion with family members. It is of utmost importance that the family members understand the MAC disease process, treatment, and side effects of medications. Significant others should be respectful of those times when patients are unable to fully participate.

Physical (sexual) relationships with the spouse or significant other may be seriously affected and require open, honest, and frank discussions. Physicians and health care professionals are expected to provide information and support to patients and family members as needed during the course of treatment.

Deanna S. York, BSN, CCM, (MAC Patient diagnosed on March 8, 2001)

Reviewed by:
Barbara Brown-Elliott, MS, MT (ASCP) SM
Richard James Wallace, Jr., MD
The University of Texas Health Science Center
Tyler, Texas

Shannon Kasperbauer, MD

• Associate Professor of Medicine
• National Jewish Health

Charles L Daley, MD

• Professor of Medicine
• National Jewish Health

C Fordham von Reyn, MD

• Section Editor — Tuberculosis; Nontuberculous Mycobacterial Infections
• Professor of Medicine
• Geisel School of Medicine at Dartmouth

Allyson Bloom, MD

• Director, Editorial Training — UpToDate
• Senior Deputy Editor — UpToDate
• Deputy Editor — Infectious Diseases
• Clinical Instructor in Medicine
• Harvard Medical School

INTRODUCTION

Treatment of nontuberculous mycobacterial (NTM) infection of the lung is dependent upon a number of factors, including the species of the infecting organism. Members of Mycobacterium avium complex (MAC) are the most common pulmonary NTM pathogens in almost all regions of the world. The three predominate species to cause human disease among the twelve species within the complex are Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium chimaera [1,2].

The treatment of MAC pulmonary infections will be reviewed here. The management of pulmonary disease caused by other slow-growing NTM, such as Mycobacterium kansasii, Mycobacterium malmoense, and Mycobacterium xenopi,and by rapidly growing mycobacterium, such as Mycobacterium abscessus, Mycobacterium fortuitum complex, and Mycobacterium chelonae, is discussed separately. (See 'Treatment of lung infection with Mycobacterium kansasii and other less common nontuberculous mycobacteria in adults' and 'Rapidly growing mycobacterial infections: Mycobacteria abscessus, chelonae, and fortuitum'.)

The epidemiology, microbiology, clinical manifestations, and diagnosis of NTM infection are also discussed elsewhere. (See 'Overview of nontuberculous mycobacterial infections' and 'Epidemiology of nontuberculous mycobacterial infections' and 'Diagnosis of nontuberculous mycobacterial infections of the lungs'.)

NTM pulmonary infection in patients with cystic fibrosis is also discussed elsewhere. (See 'Cystic fibrosis: Antibiotic therapy for chronic pulmonary infection', section on 'Nontuberculous mycobacteria'.)

CATEGORIES OF DISEASE

In general, antimycobacterial treatment of MAC should only be considered in patients who meet the clinical, radiographic, and microbiologic criteria for the diagnosis of nontuberculous mycobacterial (NTM) infection (table 1) [3]. (See 'Diagnosis of nontuberculous mycobacterial infections of the lungs'.)

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1. Clinical and Laboratory Standards Institute. Susceptibility testing of mycobacteria, nocardia spp, and other aerobic actinomyces. 3rd ed. M24. Clinical and Laboratory Standards Institute. Wayne, PA 2018.
2. Clinical and Laboratory Standards Institute. Performance standards for susceptibility testing of mycobacteria, nocardia spp, and other aerobic actinomyces. 1st ed. M62. Clinical and Laboratory Standards Institute. Wayne, PA 2018.