BACTERIAL-COLONIZATION OF DISTAL AIRWAYS IN HEALTHY-SUBJECTS AND CHRONIC LUNG-DISEASE - A BRONCHOSCOPIC STUDY

In contrast to the healthy population, distal airway bacterial coloniz ation may occur in patients with chronic lung diseases, who often have altered pulmonary defences, However, the information dealing with thi s issue is insufficient and is based mainly on nonspecific samples, su ch as sputum cultures. Using quantitative cultures of bronchoscopic pr otected specimen brush (PSB) and bronchoalveolar lavage (BAL) samples, we studied the bacterial colonization of distal airways in 16 healthy subjects, 33 patients with bronchogenic carcinoma, 18 with chronic ob structive pulmonary disease (COPD), 17 with bronchiectasis, and 32 wit h a long-term tracheostomy due to laryngeal carcinoma. All patients we re without exacerbation, and free from antibiotic treatment at least I month before the study protocol, Thresholds for quantitative cultures to define colonization were greater than or equal to 10(2) colony-for ming units (cfu). mL(-1) for PSB and greater than or equal to 10(3) cf u . mL(-1) for BAL. Only one healthy subject was colonized by a potent ial pathogenic microorganism (PPM) (Staphylococcus aureus 4x10(2) cfu . mL(-1) in a PSB culture), Colonization was observed in 14 (42%) bron chogenic carcinoma patients (19 non-PPMs, and 10 PPMs); in 15 (83%) CO PD patients (22 non-PPMs and 7 PPMs); in 15 (88%) bronchiectasis patie nts (20 non-PPMs and 13 PPMs); and in 15 (47%) long-term tracheostomy patients (5 non-PPMs and 13 PPMs), The two most frequent non-PPMs isol ated in all groups studied were Streptococcus viridans and Neisseria s pp, Haemophilus spp, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis were the most frequent PPMs isolated in bro nchogenic carcinoma, COPD, bronchiectasis and long-term tracheostomize d patients, respectively, Pseudomonas aeruginosa colonization wits inf requent in all the groups. Our results show that distal airway bacteri al colonization is a frequent feature in stable patients with chronic lung diseases and also in patients with long-term tracheostomy. Howeve r, the pattern of colonization differs among groups studied, The knowl edge of different colonization patterns may be important for future an tibiotic prophylactic strategies and for the empirical antibiotic regi mens when exacerbations occur in these patients.