Feasibility of a Chronic Foreign Body Infection Model Studying the Influence of TiO₂ Nanotube Layers on Bacterial Contamination

Abstract

Bacterial infections on the surface of medical devices are a significant problem in therapeutic approach, especially when implants are used in the living. In cardiology, pacemaker generator pocket surfaces, made in titanium alloy can be colonized by pathogen microorganism. This contamination represents a major risk of sepsis, endocarditis and localized infections for patients. A way to limit this bacterial contamination is to modify the surface topography using nano-structuration process of the titanium alloy surface of the implanted devices. The aim of this study is to evaluate the influence of TiO 2 nanotube layers on bacterial infection in the living, considering the feasibility of an animal model of chronic foreign body infection. TiO 2 nanotube layers prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution were implanted subcutaneously in Wistar rats. Three weeks after implantation, TiO 2 implants were contaminated by a Staphylococcus epidermilis strain using two different concentrations at 10 6 and 10 8 colony forming unit (CFU) in order to induce a sufficient infection level and to avoid unwanted over infection consequences on rats health during the experiments. After 28 days in the living, 75% of nanotube layers initially submitted to the 10 8 CFU inoculum were contaminated while only 25% nanotube layers initially submitted to the 10 6 CFU inoculum remained infected. This significant result underlines the influence of TiO 2 nanotube layers in decreasing the infection level. Our in vitro experiments showed that the synthesized TiO 2 nanotubes indeed decreased the Staphylococcus epidermilis adhesion compared to unanodized Ti foil.