Antimicrobial-coated endotracheal tubes : an experimental study

Objective: Antibiotic-resistant bacterial biofilm may quickly form on endotracheal tubes ( ETTs) and can enter the lungs, potentially causing pneumonia. In an attempt to prevent bacterial colonization, we developed and tested in an in-vitro study and animal study several antibacterial-coated ETTs ( silver sulfadiazine with and without carbon in polyurethane, silver sulfadiazine and chlorhexidine with and without carbon in polyurethane, silver-platinum with and without carbon in polyurethane, in polyurethane, and rose bengal for UV light). Design, setting, animals, interventions: After preliminary silver sulfadiazine in ( SSD-ETT) was selected among the coatings to be challenged every 24 h with 10(4)-10(6) Pseudomonas aeruginosa/ml and evaluated at 6 h, 24 h, and 72 h with standard microbiological studies, scanning electron microscopy, and confocal scanning microscopy. Subsequently, eight sheep were randomized to receive either a SSD-ETT or a standard ETT ( St-ETT). After 24 h of mechanical ventilation, standard microbiological studies were performed together with scanning electron microscopy and confocal microscopy. Measurements and results: In the in-vitro study SSD-ETT remained bacteria-free for up to 72 h, whereas St-ETT showed heavy P. aeruginosa growth and biofilm formation ( p < 0.01). In sheep, the SSD-ETT group showed no bacterial growth in the ETT, ventilator tubing, and lower respiratory tract, while heavy colonization was found in the St-ETT ( p < 0.01), ventilator tubing ( p = 0.03), and lower respiratory tract ( p < 0.01). Conclusion: This study describes several effective and durable antibacterial coatings for ETTs. Particularly, SSD-ETT showed prevention against P. aeruginosa biofilm formation in a 72-h in-vitro study and lower respiratory tract colonization in sheep mechanically ventilated for 24 h.