Bacterial colonization of distal airways in healthy subjects and chronic lung disease:

ABSTRACT: In contrast to the healthy population, distal airway bacterial colo-nization may occur in patients with chronic lung diseases, who often have altered pulmonary defences. However, the information dealing with this issue is insuffi-cient and is based mainly on nonspecific samples, such as sputum cultures. Using quantitative cultures of bronchoscopic protected 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 obstructive pulmonary disease (COPD), 17 with bronchiectasis, and 32 with a long-term tracheostomy due to laryngeal carcinoma. All patients were without exacerbation, and free from antibiotic treatment at least 1 month before the study protocol. Thresholds for quantitative cultures to define coloniza-tion were ≥102 colony-forming units (cfu)·mL-1 for PSB and ≥103 cfu·mL-1 for BAL. Only one healthy subject was colonized by a potential pathogenic microorgan-ism (PPM) (Staphylococcus aureus 4×102 cfu·mL-1 in a PSB culture). Colonization was observed in 14 (42%) bronchogenic carcinoma patients (19 non-PPMs, and 1