Long-term use of indwelling urinary catheters can lead to urinary tract infections and loss of catheter patency due to encrustation and blockage. Encrustation of urinary catheters is due to formation of crystalline biofilms by urease-producing microorganisms such as Proteus mirabilis. An in vitro catheter biofilm model (CBM) was used to evaluate current methods for maintaining urinary catheter patency. We compared antimicrobial-coated urinary Foley catheters, with both available catheter irrigation solutions and investigational solutions containing NVC-422 (N,N-dichloro-2,2-dimethyltaurine; a novel broad-spectrum antimicrobial). Inoculation of the CBM reactor with 10(8) colony-forming units of P. mirabilis resulted in crystalline biofilm formation in catheters by 48 h and blockage of catheters within 5 days. Silver hydrogel or nitrofurazone-coated catheters did not extend the duration of catheter patency. Catheters irrigated daily with commercially available solutions such as 0.25 % acetic acid and isotonic saline blocked at the same rate as untreated catheters. Daily irrigations of catheters with 0.2 % NVC-422 in 10 mM acetate-buffered saline pH 4 or Renacidin maintained catheter patency throughout 10-day studies, but P. mirabilis colonization of the CBM remained. In contrast, 0.2 % NVC-422 in citrate buffer (6.6 % citric acid at pH 3.8) resulted in an irrigation solution that not only maintained catheter patency for 10 days but also completely eradicated the P. mirabilis biofilm within one treatment day. These data suggest that an irrigation solution containing the rapidly bactericidal antimicrobial NVC-422 in combination with citric acid to permeabilize crystalline biofilm may significantly enhance catheter patency versus other approved irrigation solutions and antimicrobial-coated catheters.
Keywords: Antimicrobial; Biofilm; Infection; Irrigation; Urinary catheter.