Analysis of clinical characteristics and bronchoalveolar lavage fluid microbial community diversity in non-cystic fibrosis bronchiectasis patients with Pseudomonas aeruginosa colonization

This study aims to examine the differences in microbial community abundance and species distribution in the bronchoalveolar lavage fluid (BALF) obtained from non-cystic fibrosis bronchiectasis (NCFB) patients between those with and without Pseudomonas aeruginosa ( P. aeruginosa ) colonization, and to assess the impact of P. aeruginosa colonization on airway microecological imbalance in NCFB. Sixty-four patients were enrolled, grouped into P. aeruginosa -colonized (PA, 29) and non-colonized (NPA, 35) groups. Among patients with NCFB, those with P. aeruginosa colonization had greater disease severity than those without colonization, with significantly higher bronchiectasis severity index (BSI) scores ( P < 0.05). The proportions of patients with higher Bhalla and E-FACED scores were also greater in the PA group than in the NPA group (62.1% vs 42.8% and 34.1% vs 20%, respectively). Annual hospitalization frequency was numerically higher in PA (2.14 ± 2.43 vs 1.47 ± 0.86; P = 0.543). The PA group exhibited poorer pulmonary function, with significantly lower FEV1 and FEV1% predicted (both P < 0.01). In addition, NCFB patients in the PA group showed higher proportions of elevated white blood cell counts (31% vs 17.1%) and neutrophil percentages (41.4% vs 31.4%). Microbiota analysis of BALF demonstrated reduced alpha diversity in NCFB patients with P. aeruginosa colonization, with a predominance of Pseudomonas , whereas non-colonized NCFB patients had relatively higher abundances of Streptococcus , Acinetobacter , Rothia , Veillonella , and Prevotella . Overall, P. aeruginosa colonization in NCFB is associated with increased disease severity, heightened inflammation, and impaired lung function, accompanied by decreased microbial diversity, Pseudomonas dominance, and suppression of commensal taxa.

IMPORTANCE

Pseudomonas aeruginosa is a common colonizer in the airways of patients with non-cystic fibrosis bronchiectasis (NCFB), linked to disease severity, but research on its impact on clinical outcomes and airway microbiome diversity remains limited. This study compared P. aeruginosa -colonized (PA group) and non-colonized (NPA group) NCFB patients and found that the PA group had more severe disease (higher exacerbation, severity scores) and reduced bronchoalveolar lavage fluid (BALF) microbial α/β diversity (marked by Pseudomonas dominance and suppressed symbionts like Streptococcus ). These findings indicate that P. aeruginosa reshapes the microecology and is associated with airway microbial imbalance. This study confirms that P. aeruginosa colonization is a key factor in NCFB disease progression and airway microecological imbalance, highlighting reduced colonization and restored homeostasis as precision intervention strategies that inform targeted therapies.