Self‐sterilizing catheters with titanium dioxide photocatalyst thin films for clean intermittent catheterization: Basis and study of clinical use

Abstract

Clean intermittent catheterization (CIC) requires a large number of disposable catheters or a large amount of water and disinfectant. We made titanium dioxide (TiO(2))-coated catheters for CIC using technology we have developed previously, and examined the photocatalytic antibacterial effect of this catheter using only light energy and the safety of this type of catheter for practical clinical use. TiO(2)-coated catheters were filled with bacterial cell suspensions and illuminated with a 15-W black-light lamp for testing antibacterial potency. Next, we soaked control toxic materials (zinc diethyldithiocarbamate) and the tips of TiO(2)-coated catheters in M05 medium, and evaluated cell toxicity from the numbers of V79 colonies in these dilutions. Then, bodyweight curves and histological tissue changes were observed over a period of time in mouse-transplanted TiO(2)-coated catheters and control catheters. Finally, we investigated the use of these TiO(2)-coated catheters in 18 patients by questionnaire and bacterial culture of TiO(2)-coated catheters and control catheters. The survival rate of Escherichia coli in the liquid inside the TiO(2) catheter decreased to a negligible level within 60 min under ultraviolet (UV)-A illumination. The survival rate of Staphylococcus aureus, Pseudomonas aeruginosa and Serratia marcescens also decreased to a negligible level within 60 min. V79 cells showed no cytotoxicity of this catheter, and there was no difference in bodyweight or foreign body reaction between mouse-transplanted TiO(2)-coated catheters and control catheters. In a preliminary clinical analysis of 18 patients who voluntarily used this catheter, the rate of positive bacterial culture of the tips of TiO(2)-coated catheters was 20% versus 60% for conventional catheters after 4 weeks of use. TiO(2)-coated silicone catheters were easily sterilized under certain light sources and were shown to be safe in an experiment using cultured cells and in animal experiments. Sterilizing catheters with TiO(2) photocatalyst thin films are expected to be used clinically for clean intermittent catheterization after proper modification based on this study.