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, chlorhexidine in polyurethane, and rose bengal for UV light). DESIGN, SETTING, ANIMALS, INTERVENTIONS: After preliminary studies, silver sulfadiazine in polyurethane (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.