Biofilm prevention potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Background Long-term use of indwelling urethral catheters is associated with high risk of urinary tract infection (UTI) and blockage. Microbial biofilms are a common cause of catheter blockage, reduce their lifetime and significantly increase morbidity of UTIs. A 0.02% polyhexanide irrigation solution developed for routine mechanical rinsing shows potential for bacterial decolonization of suprapubic and indwelling urethral catheters and has the potential to reduce or prevent biofilm formation. Methods Using a practice-like in vitro assay and standard silicon catheters, artificially contaminated with clinically relevant bacteria, assays were carried out to evaluate the biofilm reduction and prevention potential of polyhexanide vs. no intervention (standard approach) and irrigation with saline solution (NaCl 0.9%). The biofilm mass was measured by crystal violet staining and fluorescence microscopy. Results Irrigation with a 0.02% polyhexanide solution reduced the biofilm mass by approx. 85% vs. non-treated catheters. Standard 0.9% saline solution was able to reduce the biofilm mass by approx. 50%. Fluorescence microscopy showed that polyhexanide is able to destroy bacteria in the biofilm, albeit only those cells on the upper layers. Conclusions The polyhexanide and standard saline solutions are able to reduce bacterial biofilm from urinary catheters, showing a combination of mechanical and antibacterial effects. The data supports a prevention strategy to avoid the formation of a thick biofilm, which is characteristically difficult to be efficiently removed. Further research is required to evaluate the long-term tolerability and efficacy of polyhexanide in clinical practice.