The Effect of Pseudomonas aeruginosa Infection on Clinical Parameters in Steady-State Bronchiectasis

Abstract

Study objective: To investigate the effect of Pseudomonas aeruginosa infection on clinical parameters in Chinese patients with noncystic fibrosis and steady-state bronchiectasis. Design: Prospective, cross-sectional clinicomicrobiological study with informed consent. Setting: Consecutive outpatient recruitment from a specialist bronchiectasis respiratory clinic. Patients: Outpatients (n = 100; 62 women; 55.1 ± 16.7 years old; FEV1/FVC 1.4 ± 0.7/2.1 ± 0.9 L), who had stable respiratory symptoms for more than 3 weeks. Measurements and results: Respiratory pathogens isolated from the sputum were: Pseudomonas aeruginosa (33), Haemophilus influenzae (10), Moraxella catarrhalis (2), other Gram-negative bacilli (5), Streptococcus pneumoniae (6), Staphylococcus aureus (5), mycobacteria (3), and yeast (1). Clinical parameters in patients with positive isolation of P aeruginosa were compared with those without the organism in the sputum culture (non-P aeruginosa). In the P aeruginosa group, the FEV1/FVC ratio and sputum volume were lower (p < 0.005) and higher (p < 0.0001), respectively, than those of the non-P aeruginosa group. The FEV1/FVC ratio (< 60%) and sputum volume (grading > 5) were independently associated with a positive sputum isolation of P aeruginosa with odds ratios of 3.1 (confidence interval [CI] 1.2 to 8.4; p < 0.01) and 4.7 (CI 1.6 to 13.3; p < 0.001), respectively. Conclusions: P aeruginosa is the predominant respiratory pathogen isolated in the sputum of Chinese patients with steady-state bronchiectasis, and its isolation is associated with high sputum output (≥ 75th quartile) and moderately severe airflow obstruction (FEV1/FVC < 60%).