EFFECTS OF AIRWAY INFECTION BY PSEUDOMONAS-AERUGINOSA - A COMPUTED TOMOGRAPHIC STUDY

Background - Pseudomonas aeruginosa commonly infects the airways of pa tients with bronchiectasis. A study was undertaken to examine the rela tionship between infection of the airways with this pathogen, the morp hological pattern of bronchiectasis an thin section computed tomograph ic (CT) scanning, symptom duration, smoking habits of the patients, se nd the presence of airflow obstruction. Methods - Thin section CT scan s of 22 adult patients with bronchiectasis and concurrent sputum infec ted by P aeruginosa (Pa+ve) and those of 45 randomly selected patients not infected by P aeruginosa (Pa-ve) were analysed independently by t wo thoracic radiologists, Patients with cystic fibrosis were excluded. Each scan was scored at a lobar level for extent of bronchiectasis, s everity of branchial wall thickening and dilatation, predominant patte rn of bronchiectasis, presence of mucus plugging, and degree of decrea sed attenuation of the lung parenchyma. Results - The Pa+ve group had more extensive bronchiectasis and a greater degree of branchial wall t hickening and dilatation on the CT scan than the Pa-ve group; more ext ensive decreased attenuation was seen in the Pa+ve group. These findin gs were robust on multivariate analysis; decreased attenuation was als o independently related to the duration of sputum production. Conclusi ons - Patients with bronchiectasis infected by P aeruginosa have more extensive and severe bronchiectasis on thin section CT scanning than t hose without P aeruginosa infection. The bronchi and small airways are both involved, reflecting the end result of complex interactions betw een host airways and the numerous virulence factors produced by P aeru ginosa.