Characteristics of patients with bronchoscopy-diagnosed pulmonary Mycobacterium avium complex infection

We occasionally treat patients with clinically suspected pulmonary Mycobacterium avium complex (MAC) infection and negative MAC culture on bronchoscopy.

This study aimed to investigate the usefulness of bronchoscopy in patients with suspected MAC lung disease with nodular bronchiectasis on chest computed tomography (CT) and to clarify the clinical characteristics of these patients.

We reviewed the records of 71 patients with clinically suspected pulmonary MAC infection on chest CT who underwent bronchoscopy. The patients were classified on the basis of MAC culture result, and their clinical characteristics were compared.

MAC was detected in 33 of the 71 (46.5%) patients (positive group), and 35 (49.3%) were culture-negative for nontuberculous mycobacteria (NTM) (negative group). NTM other than MAC were detected in 3 of 71 (4.2%) patients. MAC was not detected in 14 of 38 (36.8%) patients positive for GPL core IgA antibody. Patients in the positive group had a higher body mass index (20.1 ± 3.4 vs 18.5 ± 2.9 kg/m²; p = 0.047) and positive rate for GPL core IgA antibody (72.7% vs 40%; p = 0.006) and a lower chronic obstructive pulmonary disease assessment test score (6.6 ± 6.6 vs 11.7 ± 8.5; p = 0.016) and rate of positive culture for Pseudomonas aeruginosa or Haemophilus influenzae (12.1% vs 45.7%; p = 0.003), as compared with the negative group.

Bronchoscopy is useful for diagnosis of MAC in patients who cannot be diagnosed by sputum examination. In addition, patients with pulmonary MAC disease had less severe subjective symptoms and weight loss than did those with a negative MAC culture on bronchoscopy.