Self-sterilizing photoactivated catheters to prevent nosocomial infections

Bacterial colonization and biofilm formation on catheters are the primary causes of nosocomial infections and entails a limitation for their long-term use, often requiring catheter removal. Ca. 80% of the urinary tract infections contracted by patients in hospitals are catheter-associated, leading to substantial morbidity, mortality and higher costs. The increase of multi-drug resistant bacteria has created an urgent need for new strategies to prevent biofilm formation on catheters and antimicrobial photodynamic inactivation (aPDI) appears to be a promising approach. We have developed (patent pending) self-sterilizing silicone catheters with a covalently attached layer of photosensitizer (PS) that shows strong antibacterial effect in vitro against a panel of bacterial species commonly related to catheter-associated infections such as Pseudomonas aeruginosa and Staphylococcus epidermidis. Illumination with a 532 nm diode laser light of the PSderivatized catheter surfaces induced killing of 99-99.9% of the bacterial biofilm attached to it. The population survival decreased to a negligible level after 60 min of illumination and no significant decrease of the bacterial viability was observed in the absence of either light or PS. Time-resolved luminescence measurements with detection at 1265 nm confirmed generation of singlet molecular oxygen (1O2) only in PS-derivatized catheters upon illumination, paving the way for future applications to reduce the occurrence of catheter-associated urinary tract infections.