STRUCTURAL FEATURES OF TRACHEAL TUBE BIOFILM FORMED DURING PROLONGED MECHANICAL VENTILATION

The dissemination of tracheal tube biofilm into the mechanically venti lated lung has been proposed as a contributory factor in the pathogene sis of ventilator-associated pneumonia. In the present study, conventi onal light microscopy, confocal laser scanning microscopy, and scannin g electron microscopy were used to examine luminal tracheal tube biofi lm in tubes from ten consecutive medical intensive care patients. Biof ilms also were cultured, No tube contained a predominantly microbial a ggregate. Microorganisms were either dispersed throughout the biofilm or restricted to the most superficial layer. Neutrophil polymorphonucl ear cells were present in all biofilms in a pattern suggesting that a layering or stratification had taken place. The distribution of neutro phils and microorganisms was consistent with a progressive accretion o f respiratory secretions, rather than formation of a predominantly mic robial biofilm.