Background: The impact of potentially pathogenic micro-organisms (PPMs) on Chinese patients with steady-state bronchiectasis is unknown.
Methods: Peripheral blood and sputum were sampled to determine inflammatory markers and sputum bacterial density. Spirometry and diffusing capacity were measured. Quality of life was assessed using the St George's Respiratory Questionnaire.
Results: Of 144 patients with steady-state bronchiectasis, Pseudomonas aeruginosa was isolated in 44 cases (30.6%). Compared with other PPMs, P. aeruginosa had a more pronounced influence on airway inflammation and spirometry, but not on systemic inflammation or quality of life. The impact of PPMs other than P. aeruginosa on clinical indices was similar. Bacterial density was not correlated with most clinical parameters. Factors associated with PPM isolation included bronchiectasis symptoms for ⩾ 10 years (OR 2.13) and ⩾ 4 bronchiectatic lobes (OR 2.82). Having ⩾ 4 exacerbations within 2 years (OR 2.18) and cystic bronchiectasis (OR 2.23) was associated with the colonisation of PPMs, i.e., isolating an identical PPM on at least two occasions within 1 year.
Conclusion: In patients with steady-state bronchiectasis in Guangzhou, P. aeruginosa is the most common organism causing heightened airway inflammation and poor lung function. PPM isolation or colonisation should be suspected in case of longer duration of symptoms, multilobar bronchiectasis, frequent exacerbation and cystic bronchiectasis.