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

Abstract

Keiko M Tarquinio1, Nikhil K Kothurkar2, Dharendra Y Goswami3, Ronald C Sanders Jr4, Arno L Zaritsky5, Ann Marie LeVine61Division of Pediatric Critical Care Medicine, Department of Pediatrics, Rhode Island Hospital, The Warren Alpert Medical School, Brown University, Providence, RI USA; 2Department of Chemical Engineering and Materials Science, Amrita School of Engineering, Ettimadai, Coimbatore, India; 3Clean Energy Research Center, University of South Florida, Tampa, FL, USA; 4Section of Pediatric Critical Care, Department of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, Little Rock, AR, USA; 5Executive Medical Director, Children’s Hospital of The King’s Daughters, Norfolk, VA, USA; 6Pediatric Critical Care Medicine, University of Michigan Medical School, C.S. Mott Children’s Hospital, Ann Arbor, MI, USAPurpose: 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 (TiO2) coating has not been studied.Methods: Five types of ETT coatings were applied over silica layer: Ag, solgel TiO2, solgel TiO2 with Ag, Degussa P25 TiO2 (Degussa TiO2), and Degussa TiO2 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 TiO2 with Ag at 24 hours, and by Degussa TiO2 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 TiO2 with Ag and Degussa TiO2 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.Keywords: ventilator-associated pneumonia, Degussa titanium dioxide, solgel titanium dioxide, quantitative culture