Abstract
INFECTION of the lower respiratory tract is receiving increasing attention as a possible cause of chronic bronchitis and emphysema. For many years culture of expectorated material has been performed in an attempt to identify pathogenic bacteria that are assumed to emanate from the bronchial tree. There is much evidence that Haemophilus influenzae and pneumococci, organisms said to be the most frequent pathogens in chronic bronchitis,1 are commonly isolated from the mouth and pharynx of persons who have no respiratory ailment, and that oropharyngeal secretions mask the bacteriology of those expectorated from the lower respiratory passages.2 Attempts to refine technic by . . .