Characterization of bronchoalveolar lavage fluid microbiota in acute exacerbations of bronchiectasis with non-tuberculous mycobacterial detection

Objectives: Non-tuberculous mycobacteria (NTM) frequently colonize the airways of patients with bronchiectasis; however, there has been limited research into airway microbiota composition and predisposing factors for NTM detection during acute bronchiectasis exacerbations. Methods: This study enrolled 34 patients with bronchiectasis experiencing acute exacerbations. Metagenomic next-generation sequencing was used to detect microbiota in bronchoalveolar lavage fluid (BALF), and bioinformatics methods were used for the comparative analysis of meaningful microbiota in the BALF of patients with acute exacerbations of bronchiectasis. A correlation analysis was conducted to identify susceptibility factors for NTM in patients with bronchiectasis. Results: Compared with patients with community-acquired pneumonia, patients with bronchiectasis had higher detection rates of NTM (38.2%), Pseudomonas aeruginosa, and Haemophilus influenzae. Patients with NTM-positive bronchiectasis had lower body mass index and lipid profiles than patients who were NTM-negative. Metagenomic next-generation sequencing of BALF revealed patients who were NTM-positive had increased relative abundance of Rothia and other anaerobic genera compared with patients who were NTM-negative. Patients who were NTM-positive also showed higher levels of Streptococcus parasanguinis at the species level. Elevated Rothia mucilaginosa and S. parasanguinis correlated with decreased percentages of clusters of differentiation 3+ T lymphocytes and clusters of differentiation 3+ T-cell subgroups in peripheral blood. Conclusions: NTM colonization increases the risk of acute bronchiectasis exacerbations. Low body mass index, lipid levels, and isolation of R. mucilaginosa and S. parasanguinis in BALF are susceptibility factors for NTM colonization in patients with bronchiectasis.