• clean intermittent catheterization (CIC);
  • self-sterilizing catheter;
  • TiO2 photocatalyst

Objective:  Clean intermittent catheterization (CIC) requires a large number of disposable catheters or a large amount of water and disinfectant. We made titanium dioxide (TiO2)-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.

Methods:  TiO2-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 TiO2-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 TiO2-coated catheters and control catheters. Finally, we investigated the use of these TiO2-coated catheters in 18 patients by questionnaire and bacterial culture of TiO2-coated catheters and control catheters.

Results:  The survival rate of Escherichia coli in the liquid inside the TiO2 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 TiO2-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 TiO2-coated catheters was 20% versus 60% for conventional catheters after 4 weeks of use.

Conclusion:  TiO2-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 TiO2 photocatalyst thin films are expected to be used clinically for clean intermittent catheterization after proper modification based on this study.