Novel Antiseptic Urinary Catheters for Prevention of Urinary Tract Infections: Correlation of In Vivo and In Vitro Test Results

Urinary catheters are widely used for hospitalized patients and are often associated with high rates of urinary tract infection. We evaluated in vitro the antiadherence activity of a novel antiseptic Gendine-coated urinary catheter against several multidrug-resistant bacteria. Gendine-coated urinary catheters were compared to silver hydrogel-coated Foley catheters and uncoated catheters. Bacterial biofilm formation was assessed by quantitative culture and scanning electron microscopy. These data were further correlated to an in vivo rabbit model. We challenged 31 rabbits daily for 4 days by inoculating the urethral meatus with 1.0 × 10⁹ CFU streptomycin-resistant Escherichia coli per day. In vitro, Gendine-coated urinary catheters reduced the CFU of all organisms tested for biofilm adherence compared with uncoated and silver hydrogel-coated catheters (P < 0.004). Scanning electron microscopy analysis showed that a thick biofilm overlaid the control catheter and the silver hydrogel-coated catheters but not the Gendine-coated urinary catheter. Similar results were found with the rabbit model. Bacteriuria was present in 60% of rabbits with uncoated catheters and 71% of those with silver hydrogel-coated catheters (P < 0.01) but not in those with Gendine-coated urinary catheters. No rabbits with Gendine-coated urinary catheters had invasive bladder infections. Histopathologic assessment revealed no differences in toxicity or staining. Gendine-coated urinary catheters were more efficacious in preventing catheter-associated colonization and urinary tract infections than were silver hydrogel-coated Foley catheters and uncoated catheters.In the United States, nosocomial catheter-related urinary tract infections (UTIs) account for almost 1 million cases (24) and approximately 31% of nosocomial infections seen in the intensive care unit each year (16). Approximately 10% to 30% of patients with indwelling bladder catheters develop bacteruria or UTI (24). This contributes not only to increased morbidity and mortality but also to longer hospital stays and increased medical costs (13). Microbiologic cultures of catheter-related UTIs in the intensive care unit reveal several common pathogens. Of these, Escherichia coli and Pseudomonas aeruginosa account for over 39%.Several different methods have been used to prevent nosocomial UTIs. Of these, the most common and longest-used method is the sterile closed drainage system, which has substantially reduced the prevalence of catheter-associated UTIs (11). More recently, other preventive methods involving the use of antimicrobial devices, including urinary catheters impregnated with silver, nitrofurazone, and a combination of minocycline and rifampin (rifampicin), have led to a reduced incidence of bacteruria; however, they were not significant at preventing catheter-related UTIs compared to results with uncoated controls (4, 12, 22).The use of antibiotic (minocycline and rifampin)-impregnated catheters has led to a reduced incidence of gram-positive bacteruria (4). However, given the fact that bacterial resistance to antibiotics has been increasing, this has resulted in a demand for an alternative means of an antiseptic coating that has not been associated with increased resistance. At the M. D. Anderson Cancer Center, we developed a technique of impregnating urinary catheters with Gendine, a novel antiseptic dye consisting of Gentian violet and chlorhexidine, to prevent catheter-related UTIs. In this study, we evaluated Gendine-coated silicone urinary catheters (GND-UCs) for their in vitro antimicrobial efficacy at inhibiting microbial biofilm formation on catheter surfaces and at reducing the incidence of UTIs in an in vivo rabbit model in comparison with results for silver hydrogel-coated catheters and uncoated Foley catheters.