DEAR DR. GOTT: A family member was recently diagnosed with mycobacteria avium complex pulmonary disease, also known as MAC. Can you please provide information on this unheard of condition? What causes it? Is it contagious? What are the symptoms? What exactly is it? Can it be cured or is it a lifetime thing? Can it recur if it is cured? What is the treatment?
Please provide as much information as possible and as soon as possible. Thank you so much. Please keep up the good work of providing medical information with a common sense approach.
DEAR READER: Mycobacterium avium complex (MAC) is essentially a pulmonary pathogen for those on immuno-suppressive chemotherapy and refers to both non-tuberculosis M. intracellulare and M. avium bacteria. . It has also been linked with osteomyelitis (an infection of the bone and bone marrow), synovitis (swelling of the membrane of a joint’s inner layer), or synosynovitis (swelling of a tendon sheath). It is the most common cause of infection by non-tuberculosis mycobacteria in AIDS patients. Some studies have reported a connection with Crohn’s disease and a hypersensitivity pneumonitis-like reaction (better known as hot-tub lung) in those individuals exposed to aerosolized MAC, although more research is necessary for better clarification.
The disease is transmitted through inhalation and ingestion that is ultimately absorbed into the gastrointestinal tract. Through what appears to be a rather complex system, it is carried to the lymph nodes. In those with a weakened immune system, it can spread to the liver, spleen, bone marrow, and other sites. Of high concern is pulmonary disease in patients without HIV infection. It has also been associated with bronchiectasis (irreversible widening of the bronchial walls).
Symptoms of infection commonly begin with a cough, weight loss, night sweats, the production of sputum and lethargy that can be present for weeks or months. We have all experienced many of the symptoms relating to MAC so no wide-spread alarm bell should ring. However, if unusual signs are present that cause concern, a visit to a primary care physician or pulmonologist is appropriate.
Pulmonary MAC infection is associated with lung cancer, cystic fibrosis, chronic obstructive pulmonary disease (COPD), bronchiectasis and more.
Testing for a possible pulmonary infection includes acid-fast bacillus staining and a culture of sputum specimen. If widespread infection is suspected, blood and urine cultures will likely also be ordered.
Treatment is with prescription drugs. Those most commonly prescribed include rifamycins, macrolides and ethambutol. Aminoglycosides are also used as additional agents. Should MAC lymphadenitis occur in children, surgical excision of the affected nodes may be recommended.
Surprisingly, MAC infection is classed as a non-reportable infectious disease, despite the fact that the CDC reports an incidence of one case per every 100,000 individuals per year. Treatment success rates vary. Those with complex symptoms have a 90% chance of recovery with a 20% chance of relapse following treatment. Those with significant lung disease who do not seek treatment run the risk of weight loss and the development of respiratory insufficiency which can lead to severe disability and even death.
Readers who would like related information can order my Health Report “Pulmonary Disease” by sending a self-addressed, stamped number 10 envelope and a $2 US check or money order to my attention at PO Box 433, Lakeville, CT 06039. Be sure to mention the title when writing or print out an order form from my website www.AskDrGottMD.com.
