Pseudomonas aeruginosa Phenotypes Associated with Radiological Severity in Non-Cystic Fibrosis Bronchiectasis

Background Pseudomonas aeruginosa (PA), the most significant respiratory pathogen in patients with non-cystic fibrosis (CF) bronchiectasis, exhibits various phenotypes in vitro . We hypothesized that PA phenotypes are associated with radiographic severity in adults with non-CF bronchiectasis. Methods We conducted a retrospective cross-sectional study to determine the association between PA phenotypes and radiographic severity. We analyzed 140 adults with non-CF bronchiectasis who underwent high-resolution computed tomography (HRCT) between July 2022 and December 2023. We characterized 12 bacterial phenotypes of PA isolates in vitro from patients with positive PA cultures obtained from bronchoalveolar lavage fluid samples and evaluated the radiographic severity of the 140 patients using HRCT (Reiff, Bhalla, and bronchiectasis radiologically indexed CT score (BRICS)) scores. We examined the correlation between the PA phenotypes and the HRCT scores using univariate analysis. The relationship between Reiff scores and PA phenotypes was analyzed using multilevel regression models for linear regression. Results The Reiff, Bhalla, and BRICS scores were higher in PA-positive patients than in PA-negative patients, with a lower FEV ₁ % predicted. The three most prevalent phenotypes of the PA isolates were reduced twitching motility (41 out of 44 [93%]), reduced swimming motility (33 out of 44 [75%]), and smooth colony surface (33 out of 44 [75%]). The HRCT scores were significantly correlated with five PA phenotypes in the univariate analysis (Reiff score: swimming motility ( P  = 0.001), swarming motility ( P  = 0.005), twitching motility ( P  = 0.024), colony size ( P  = 0.031), and mucoidy ( P  = 0.005); Bhalla score: swimming motility ( P  = 0.039); BRICS: colony size ( P  = 0.003)) including swimming motility, swarming motility, twitching motility, colony size, and mucoidy. The correlation between swimming (P  = 0.012), swarming ( P  = 0.004), colony size ( P  = 0.006), and the Reiff score was statistically significant after model construction. Conclusions Three easily assayed colony PA phenotypes (swimming, swarming, and colony size) were associated with Reiff scores, which may represent independent risk factors for determining radiographic severity in patients with non-CF bronchiectasis with PA infection.