A comparative study of experimental urinary catheters containing silver and zinc for biofilm inhibition.

Both commercial and experimental antibacterial urinary catheters were investigated for their efficacy in preventing planktonic growth and biofilm formation of bacteria in a synthetic urine solution. Experimental antibacterial catheters having thin (<500 µm) dispersions of Ag, Ag/AgO, or Zn/AgO in polydimethylsiloxane (PDMS) binder all exhibited significant antimicrobial activity, outperforming traditional commercial antibacterial catheters. All experimental catheters prevented planktonic growth of bacteria and did not exhibit biofilm formation during a six-day test period using a colony forming unit (CFU) measurement method. On the other hand, the best performing commercial catheters demonstrated efficacy for only 3 days in planktonic growth tests and formed multiple bacterial colonies in CFU measurements. The Zn/AgO/PDMS experimental catheter was the only catheter observed to produce hydrogen peroxide, a reactive oxygen species known to inhibit biofilm formation; lack of detectable hydrogen peroxide production by the AgO/PDMS and Ag/AgO/PDMS experimental catheters suggests that bactericidal action most likely arises from release of silver ions present in the PDMS coatings.