Infection with the Mycobacterium avium complex in patients without predisposing conditions: a case report and literature review

Nontuberculous Mycobacteria (NTM), especially Mycobacterium avium-intracellulare complex (MAC), has been considered responsible for human disease, especially in HIV patients. Nevertheless, it has been diagnosed in immunocompetent elderly men, frequently with previous pulmonary disease: chronic obstructive lung disease (COPD), complications of tuberculosis, pulmonary fibrosis and bronchiectasis. We relate the case of a female patient, 51 years old, with continuously acid fast bacilli (AFB) smears and with three previous treatments, which were conducted at the multiresistant tuberculosis (MRTB) service. MAC was identified in the sputum culture, and she received treatment for one year. The posterior sputum exams were negative. The cavity lesions observed in the high-resolution computed tomography (HRCT) were reduced, and some of the nodule lesions became bronchiectasis, even after the end of treatment. We agree with the literature reports that indicate that MAC is the cause of bronchiectasis. It is necessary to identify the type of mycobacteria in immunocompetent individuals with positive AFB smears that do not become negative with tuberculosis treatment.