A newly designed tympanostomy stent with TiO 2 coating to reduce Pseudomonas aeruginosa biofilm formation

Abstract

Biofilm formation has been implicated as a cause of post-tympanostomy tube otorrhea in patients suffering from otitis media with effusion, and biofilms have been found to adhere to all available types of tympanostomy tubes (TT) made from silicone. In this study, we present a novel stent designed with a reduced surface area and a titanium dioxide (TiO₂) coating to prevent biofilm formation. Using a radio frequency power supply, tympanostomy stents (TS) made from Nitinol (Nikel-titanium) were coated with TiO₂ to form an oxide layer on the metallic target. We successfully reproduced biofilms with carbenicillin-resistant Pseudomonas aeruginosa strain, PAO1-GFP (green fluorescent protein) on the tubes in vitro. We then compared the levels of biofilm formation by this strain on the two types of implants using several methods, including bacterial quantification, electron microscopy, and confocal laser fluorescent microscopy. Our results provide definitive evidence that the combination of the TiO₂ coating and minimized surface area of the Nitinol stent inhibited the P. aeruginosa biofilm formation. The ability of the TS to prevent viable bacteria colonization (over 10 folds, compared to silicone TT) was verified by anti-biofilm test. Future studies will reveal more useful in reducing otorrhea and plugging complications as a novel tympanostomy tube.