Mycobacterium avium-intracellulare (M. avium Complex, MAC) can cause several types of chronic lung infections. One type resembles cavitary tuberculosis.
Common candidate:
(1) older adult
(2) male
(3) history of chronic smoking and/or alcohol abuse
(4) history of COPD or other chronic lung disease
Clinical findings:
(1) chronic cough with sputum production
(2) dyspnea
(3) variable hemoptysis
(4) variable fatigue
(5) variable anorexia with weight loss
(6) variable fever
(7) variable night sweats
Pulmonary findings:
(1) MAC lesions are primarily in the upper lobes, with cavitary lesions and nodules.
(2) Changes associated with the underlying lung disease.
Diagnosis may be delayed since symptoms are assumed to be due to progession of the underlying lung disease. Identification of acid fast bacilli (AFB) on smear or culture is key to the diagnosis.
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