NEW YORK (Reuters Health) – Results of in vitro testing indicate that silver impregnation of urinary catheters has little effect on bacterial adherence, reinforcing findings from clinical studies that question the value of the devices in reducing rates of urinary tract infection.

That’s according to a report in the December issue of The Journal of Urology by Dr. Barbara Trautner and colleagues with Baylor College of Medicine, Houston, Texas.

“Our findings emphasize the limitations of the data in support of the use of silver catheters to prevent catheter-associated urinary tract infections,” Dr. Trautner told Reuters Health in an email. “Very little in vitro data are available concerning the effect of silver on bacterial adherence to catheters.”

Dr. Trautner’s team studied the ability of uropathogens to adhere to catheters impregnated with silver or nitrofurazone. They tested six types of commercially available 12Fr Foley catheters, including coated and uncoated silicone or latex catheters, as well as brands with hydrogel coating.

After segments of the catheters were incubated in broth for varying numbers of days, they were then incubated overnight with E. coli or E. faecalis.

The adherence of the pathogens to nitrofurazone catheters was significantly less than to silicone-only catheters for periods of pre-incubation up to 3 days for E. faecalis and up to 5 days for E. coli. The anti-adherence effect of nitrofurazone was lost with longer periods 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,” the researchers found. Silver did decrease the adherence of E. faecalis to latex-hydrogel catheters but not to silicone- hydrogel catheters, according to the report.

“Our study confirms earlier findings of Johnson et al that silver does not significantly decrease pathogen adherence to catheters in vitro,” Dr. Trautner stated. “Silver urinary catheters have not shown consistent benefit in clinical trials,” she added.

The authors note that silver- or nitrofurazone-impregnated catheters are more expensive than regular catheters, by a margin of 80% to 130%. “Even in this era of zero tolerance for hospital acquired infections it seems highly questionable whether these currently available antimicrobial catheters are worth the investment of limited health care dollars,” they conclude.

Reference:

Silver or Nitrofurazone Impregnation of Urinary Catheters Has a Minimal Effect on Uropathogen Adherence

J Urol 2010;184:2565-2571.