MAC Lung Disease

MAC lung disease is an infection caused a group of bacteria called Mycobacterium avium complex (MAC). MAC includes two closely related species, Mycobacterium avium and Mycobacterium intracellulare, and may also be referred to as MAI. MAC is one of a large group of nontuberculous mycobacteria (NTM), and the most common cause of NTM lung disease in the U.S.

MAC organisms are common in soil and water and are easily inhaled during daily activities. Most of the time they cause no harm, but they can cause infection in groups with certain risk factors. These groups include people living with lung disease such as bronchiectasis and COPD, and people with a weakened immune system because of an autoimmune disorder or medical treatment such as drugs that compromise immunity. Postmenopausal women and people over 65 years old are also more likely to develop MAC lung disease than the general public.

Key Facts

  • MAC infection is a serious condition that can cause damage to the lungs.
  • MAC infection is not contagious.
  • Common signs and symptoms of MAC lung disease include fatigue, chronic cough, shortness of breath, night sweats, coughing up blood and weight loss. Symptoms may persist or worsen despite being treated for another lung condition.
  • MAC lung disease diagnosis includes a clinical exam, a chest x-ray or CT scan and a lab culture of sputum from your lungs.
  • MAC lung disease treatment usually involves a combination of antibiotics taken over an extended period of time.
  • In addition to lung disease, MAC can also cause an infection that spreads throughout the body, usually in people with advanced AIDS, called disseminated MAC disease, as well as a swelling in the lymph nodes called lymphadenitis that is most common in young children.

For more information about MAC lung disease symptoms, diagnosis and treatment, see our pages on nontuberculous mycobacterial lung disease.

Development of this educational content was supported by a collaborative sponsorship from Insmed Incorporated.

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