The impact of bronchiectasis on the lung microbiota of community-acquired pneumonia patients: An mNGS-based study

Changes in lung microbiota are associated with bronchiectasis and its clinical parameters. However, it is unclear whether distinct microbiota patterns reflect the characteristic lung status in bronchiectasis.

This study aimed to identify key microbiota associated with community-acquired pneumonia (CAP) complicated with bronchiectasis and explore its relationship with clinical features.

A single-center retrospective study enrolled 59 CAP patients who underwent bronchoscopy. Bronchoalveolar lavage samples were analyzed using metagenomic next-generation sequencing. The top 10 bacterial species and α- and β-diversity indices were compared between patients with and without bronchiectasis. Linear discriminant analysis was used to identify distinctive microbes. Spearman was used to analyze the correlation between the distinctive microbes and clinical characteristics.

The CAP with bronchiectasis group was dominated by Pseudomonas, while Prevotella dominated the non-bronchiectasis group. The bronchiectasis group had significantly lower α-diversity and distinct β-diversity compared to the non-bronchiectasis group. Stutzerimonas was identified as a key microbe in the bronchiectasis group, positively correlated with lymphocyte percentage and count, and negatively correlated with neutrophil percentage. Pseudomonas aeruginosa and Nocardia pneumoniae were key species in the bronchiectasis group.

The composition and diversity of lung microbiota in patients with CAP combined with bronchiectasis are significantly different. The genus Stutzerimonas can serve as a key marker to distinguish bronchiectasis from non-bronchiectasis patients to reflect the characteristic lung microbiota status. This study provides a potential basis for disease stratification and personalized management.