We surveyed bronchial microflora by alternate-day, non-directed bronchial lavage (NBL) in 150 patients requiring mechanical ventilation on an intensive care unit. This simple technique uses a 20 ml non-bronchoscopic lung lavage, then quantitative bacterial culture. NBL bacteriological findings were identical to those obtained by same-day bronchoscopic broncho-alveolar lavage on 16/20 occasions. Using serial NBLs, the bronchial bacterial population was characterized during 65 episodes of pneum...