An effective evidence-based cleaning method for the safe reuse of intermittent urinary catheters: In vitro testing.

AIMS: To determine a safe bactericidal cleaning method that does not damage urethral catheters used for intermittent catheterization. In some countries, single-use catheters are the norm; in others, the reuse of catheters is common depending on health insurance, personal preference, or individual concerns about the environment. However, no recent study of cleaning methods has been published to provide evidence for the safe reuse of catheters. METHODS: Using advanced microbiological methods, a laboratory study of eight cleaning methods was conducted. Sections of uncoated polyvinylchloride (PVC) catheters were exposed to bacterial uropathogens in physiologically correct artificial urine media then tested with a range of heat, chemical, and mechanical cleaning methods. Analysis of culturable and viable but nonculturable (VBNC) bacteria was done and direct microscopy was used. Descriptive statistics were used to compare values. RESULTS: Heat treatments, although effective, resulted in catheter surface breakdown and damage. Ultrasonic cleaning and vinegar showed evidence of VBNC populations indicating the methods were bacteriostatic. Detergent and water wash followed by immersion in a commercially available 0.6% sodium hypochlorite solution and 16.5% sodium chloride (diluted Milton) gave consistent bactericidal results and no visible catheter damage. CONCLUSIONS: Combined mechanical and chemical treatment of a detergent and water wash followed by immersion in diluted Milton (the "Milton Method") provided consistent and effective cleaning of uncoated PVC catheters, showing bactericidal action for all uropathogens tested after repeated exposure. If found safe in clinical testing, this method could increase the reuse of catheters, reduce plastic waste in the environment, reduce cost, and increase patient choice.

An electrified catheter to resist encrustation by Proteus mirabilis biofilm.

PURPOSE: We investigated the effect of iontophoresis produced by passing an electric current through silver electrodes attached to catheters on catheter encrustation by crystalline Proteus mirabilis biofilm. MATERIALS AND METHODS: Four glass bladder models were catheterized with 16Fr silicone catheters, of which 3 had 0.25 mm silver wires running through and beside the lumen. Two wired catheters had the silver wires connected to a 9 V direct current source supplying a steady current of 150 microA via a self-regulating circuit. Artificial urine, which had been inoculated with a clinical strain of P. mirabilis isolated from an encrusted catheter, was instilled into the bladder model at 0.5 ml per minute. The models were operated until the test catheters became blocked. Mean blockage time was statistically analyzed by ANOVA. Bacterial colony count, silver ions and pH were assessed every 24 hours. RESULTS: The experiment was repeated 3 times. Time to blockage, colony count, pH and scanning electron microscopy was used to assess encrustation in electrified and control catheters. Time to blockage in electrified vs control catheters was 156 vs 22 hours. The difference in blockage times was statistically significant (p <0.002). The viable bacterial cell count in urine with test catheters vs that in controls was 1.12 x 10(4) vs 2.73 x 10(9) cfu/ml. The pH increased to 9 in control models, whereas it remained less than 6.5 in test models for about 100 hours. CONCLUSIONS: Electrified catheters released ions in urine that have the oligodynamic property of inhibiting bacterial growth. The application of electric current to catheters fitted with silver electrodes significantly decreased the rate at which these devices became encrusted by P. mirabilis. This principle could be used to prevent encrustation on long-term catheters.