Oropharyngeal flora as a source of bacteria colonizing the lower airways in patients on artificial ventilation.

During 1 year 27 patients admitted to the respiratory intensive care unit were monitored bacteriologically for a minimum of 10 days (mean: 26.7 days). Oropharyngeal swabs and tracheal aspirates were qualitatively and semi-quantitatively cultured twice weekly. A correlation between oropharyngeal and tracheal flora was found: once a bacterial species colonized the oropharyngeal cavity in high numbers, the identical microorganism was frequently isolated (greater than 50%) from the lower respiratory tract. Six of the 27 patients acquired an infection of the lower airways in the respiratory intensive care unit. The bacteria involved belonged to the patients oropharyngeal flora: S. aureus, Enterobacteriaceae and Pseudomonadaceae. As a result of this study showing the oropharynx to be the source of lower airway colonization/infection, a policy for infection prevention has been outlined. This policy is based on the concept of source elimination by means of oropharyngeal decontamination.