INVESTIGATIVE UROLOGY

doi: 10.1590/S1677-553820090006000021

Uropathogen interaction with the surface of urological stents using different surface properties
Lange D, Elwood CN, Choi K, Hendlin K, Monga M, Chew BH
Stone Centre at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
J Urol. 2009; 182: 1194-200

• Purpose: Ureteral stents commonly become infected or encrusted. Various coatings have been developed to decrease bacterial adherence. To our knowledge there has been no in vitro testing of coating with heparin to date. We determined the effects of heparin coating on bacterial adherence of common uropathogens and physical stent properties.
  Materials and Methods: Heparin coated Radiance ureteral stents (Cook) and noncoated Endo-Sof control stents were tested against triclosan eluting Triumph(R) stents and noneluting Polaris control stents for adherence of Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus and Pseudomonas aeruginosa for 7 days. Adherent bacteria were determined and biofilms were visualized using fluorescent dyes. Radial, tensile and coil strength of the Radiance and Polaris stents was compared to determine the effect of heparin coating on physical stent characteristics.
  Results: Heparin coating did not decrease bacterial adhesion compared to its control. E. coli adhesion was limited by all stents tested. The Polaris stent showed significantly greater resistance to bacterial adherence for Klebsiella, Pseudomonas and Enterococcus than the Endo-Sof and Radiance stents but was more susceptible to S. aureus adherence. The Triumph stent resisted all bacteria except Pseudomonas and Enterococcus. Mature biofilms were observed on all stents with lower viability on the Triumph stent. Radiance stents showed higher tensile and lower compression strength than its control.
  Conclusions: Heparin coating does not decrease bacterial adherence to ureteral stents. Drug eluting antimicrobials have an inhibitory effect on bacterial adherence and the Polaris stent showed the least bacterial adherence of the nondrug eluting ureteral stents tested.

• Editorial Comment
  This is an important study on the ability of five common urological pathogens (Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa) to adhere and form biofilms on commercially available ureteral stents. Also, it was evaluated the impact of heparin coating on stent compression, tensile and coil strength.
  This research opens new avenue to a very common and up-to-date problem that is bacterial encrustation and adhesion to stents. It could help modifications in stent design and also in developing drugs to inhibit bacterial adhesion and biofilm formation. I recommend this article as a reference for study design and methodology to all researchers interest in the issue of stent incrustation by bacteria.

Dr. Francisco J. B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, RJ, Brazil
E-mail: sampaio@urogenitalresearch.org