Silver or nitrofurazone impregnation of urinary catheters has a minimal effect on uropathogen adherence

Bacterial adherence to the urinary catheter is an early step in biofilm formation and the pathogenesis of catheter associated urinary tract infection. We studied in vitro the effect of silver or nitrofurazone impregnation of urinary catheters on uropathogen ability to adhere to urinary catheters.

We studied commercially available nitrofurazone-silicone, silicone only, silver-silicone-hydrogel, silicone-hydrogel, silver-latex-hydrogel and latex-hydrogel catheters. Catheters were incubated in sterile broth for 0, 3, 5, 7 and 10 days, respectively, before inoculation and overnight incubation with Escherichia coli or Enterococcus faecalis.

Adherence of E. coli and E. faecalis to nitrofurazone catheters was significantly decreased compared to that of silicone-only catheters when catheters were fresh. The anti-adherence effect of nitrofurazone on E. coli decreased with time but was still significant at 5 days. For E. faecalis the effect of nitrofurazone was lost by 3 days of pre-incubation. E. coli adherence was not significantly decreased on silver impregnated catheters compared to that on control catheters of the same base material. Silver was associated with a significant decrease in E. faecalis adherence to latex-hydrogel catheters but not to silicone-hydrogel catheters. The adherence of each species to silicone catheters with hydrogel was significantly lower than that to silicone-only control catheters.

Silver impregnation had little effect on bacterial adherence in our model and nitrofurazone impregnation had a significant effect only for the first 5 days. Our results do not support a role for silver urinary catheters to prevent catheter associated urinary tract infection by decreasing bacterial adherence.