Editorial on: In Vitro Effects of a Novel Coating Agent on Bacterial Biofilm Development on Ureteral Stents by Szell et al. (From: Szell T,Dressler FF,Goelz H,et al. J Endourol 2019;33:225–231;DOI: 10.1089/end.2018.0616)

Although ureteral stents have been an essential part of the inception of endourology and have revolutionized urology as we know it, they are unfortunately also the cause of a plethora of stent-related symptoms, sparing only the lucky few as symptoms have been reported in up to 80% of patients. ¹ Owing to the medium in which it dwells and the seemingly inevitable biofilm formation on the stent surface, infection and encrustation are unfortunately not infrequently associated. ² The search for an all-resisting (co)polymer or surface coating has been the subject of years and millions worth of research. Despite numerous efforts and four decades of attempts, the Holy Grail has not yet been uncovered and an all-resisting ureteral stent still does not exist.

Szell and colleagues ³ continue this search and report the in vitro findings of a novel hydrogel-based coating on polyurethane disks in human urine, kindly provided by the lead author of the article. This coating consists of poly(N,N-dimethylacrylamide) or PDMAA and had been demonstrated to resist protein and human blood cell adhesion. The authors were able to demonstrate that this coating provides a significantly reduced amount of bacterial attachment with Escherichia Coli after 24–48 hours in an infected urinary environment in comparison with a noncoated device. Unfortunately, attachment of other uropathogens such as Klebsiella pneumoniae and Enterococcus faecalis was not adequately reduced with this coating, suggesting other mechanism of action in colonization of stent surface. Further in vitro and in vivo testing is necessary to demonstrate whether or not this coating will prove itself a worthy opponent of biofilm formation, infection, and stent encrustation, and can be used for in-human purposes.

The reason that the perfect stent or bladder catheter has not yet been developed may be partly because of an incomplete understanding of biofilm formation and its composition on devices indwelling in a urinary environment. With only few attempts at trying to elucidate the formation of conditioning film of biofilm, there is definitely room for improvement and work to be done to better understand what we are up against. ^{4 –6} This may eventually show us the path to the Holy Grail and help identify patients who may be more susceptible to stent encrustation. From a different perspective, if the indwelling foreign object cannot be optimized to withstand the medium, then maybe we should be trying to modify the medium rather than the foreign object. As chemolitholysis of uric acid and infectious stones can be achieved with urinary pH modulation, medical prevention of stent encrustation and even infection may be a topic of research yet to be uncovered and the combined approach may hold the key. ^7,8 In any case, such as Szell and colleagues, ³ we should not give up the search and every effort may bring us one step closer to the solution.