Abstract
Introduction: The role of bacterial biofilm, within the endotracheal tube (ETT), in the pathogenesis of respiratory infections is still under debate
Objectives: To study effects of length of stay under mechanical ventilation (MV) on bacterial biofilm translocation from within the ETT into health and injured lungs
Methods: ETTs colonized by biofilm were obtained from an associated study where pigs underwent oropharyngeal bacterial challenge by Pseudomonas Aeruginosa (PA) and 72h MV. Those ETTs were used in 8 healthy pigs (32.1±2.5 kg) on MV (VT 8ml/kg, PEEP 0, RR adjusted based on pH, TI/TTOT 0.25). Pigs were randomized into 4 groups (2 pigs/group) to be MV up to 24h (Group1), 48h (Group2), 72h (Group3) and 48h with lung injury caused by oleic acid (OA) (Group4). Upon autopsy, 4 samples from trachea and main bronchi and 7 from segmental bronchi were excised for PA quantification
Results: In pigs of group 3, 1 hour after OA instillation, PaO2/FiO2 decreased to 189.8±27.7. Upon extubation, ETT PA colonization was 5.7±1.6, 6.4±0.5, 6.7±0.5 and 7.6±0.6 log cfu/cm in groups 1-4, respectively (p=0.21). As depicted in figure 1, the airway tissue/ETT PA colonization ratio of trachea and main bronchi was 0.59±0.37. Colonization of segmental bronchi was infrequent.
Conclusions: Bacteria from within the ETT PA biofilm rapidly translocate up to the main bronchi, however distal colonization is uncommon even when lung are injured.
- © 2011 ERS