Bactericidal effects of silver plus titanium dioxide-coated endotracheal tubes on Pseudomonas aeruginosa and Staphylococcus aureus

PURPOSE Ventilator-associated pneumonia (VAP) is a nosocomial infection resulting in significant morbidity and mortality. Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) are pathogens associated with VAP. Silver (Ag) coating of endotracheal tubes (ETTs) reduces bacterial colonization, however titanium dioxide (TiO(2)) coating has not been studied. METHODS Five types of ETT coatings were applied over silica layer: Ag, solgel TiO(2), solgel TiO(2) with Ag, Degussa P25 TiO(2) (Degussa TiO(2)), and Degussa TiO(2) with Ag. After ETTs were incubated with P. aeruginosa or S. aureus; colonization was determined quantitatively. RESULTS Pseudomonas aeruginosa and S. aureus grew for 5 days on standard ETTs. Compared to standard ETTs, P. aeruginosa growth was significantly inhibited by solgel TiO(2) with Ag at 24 hours, and by Degussa TiO(2) with Ag at 24 and 48 hours after inoculation. No significant difference in S. aureus growth was observed between the control and any of the five coatings for 5 days. CONCLUSION In vitro, solgel TiO(2) with Ag and Degussa TiO(2) with Ag both attenuated P. aeruginosa growth, but demonstrated no effect on S. aureus colonization. Further studies using alternative coating and incorporating UV light exposure are needed to identify their potential utility in reducing VAP.