Restriction of in vivo infection by antifouling coating on urinary catheter with controllable and sustained silver release: a proof of concept study

Background: Catheter Associated Urinary Tract Infections are among the most common urological infections world wide. Bacterial biofilms and encrustation cause significant complications in patients with urinary catheters. The objective of the study is to demonstrate the efficacy and safety of an anti-microbial and anti-encrustation silver nanoparticle (AgNP) coating on silicone urinary catheter in two different animal models. Methods: Antifouling coating (P3) was prepared with alternate layers of polydopamine and AgNP and an outermost antifouling layer. Sixteen C57BL/6 female mice and two female PWG Micropigs (R) were used to perform the experiments. In mice, a 5 mm long silicone catheter with or without P3 was transurethrally placed into the urinary bladder. Micropigs were transurethrally implanted - one with P3 silicone catheter and the other with commercially available silver coated silicone catheter. Both models were challenged with E coli. Bacteriuria was evaluated routinely and upon end of study (2 weeks for mice, 3 weeks for micropigs), blood, catheters and bladders were harvested and analysed for bacterial colonization and encrustation as well as for toxicity. Results: Lower bacterial colonization was seen on P3 catheters as well as in bladders of animals with P3 catheter. Bacteriuria was consistently less in mice with P3 catheter than with uncoated catheters. Encrustation was lower on P3 catheter and in bladder of micropig with P3 catheter. No significant toxicity of P3 was observed in mice or in micropig as compared to controls. The numbers were small in this proof of concept study and technical issues were noted especially with the porcine model. Conclusions: Antifouling P3 coating reduces bacterial colonization on catheter and in animal bladders without causing any considerable toxicity for 2 to 3 weeks. This novel coating could potentially reduce the complications of indwelling urethral catheters.