In Vitro Multicompartmental Bladder Model for Assessing Blockage of Urinary Catheters: Effect of Hydrogel Coating on Dynamics of Proteus mirabilis Growth

Objectives

To investigate the effect of a hydrogel coating on the dynamics of bacterial growth in laboratory models of the catheterized bladder. Infection of the urinary tract by Proteus mirabilis can result in catheter blockage by crystalline biofilm, a common complication in patients undergoing long-term bladder catheterization.

Methods

Two series of catheters were tested in the infected bladder models: test series 1, silicone catheters impregnated with triclosan (0.5%, 1%, 4%), or silicone catheters with 0% triclosan impregnated with pure solvents and hydrogel coated (based on polyvinylpyrrolidone); and test series 2, silicone catheters, hydrogel-coated with hydrogel plus iodine (polyvinylpyrrolidone plus iodine) or hydrogel plus polyhexamethylene biguanide. Test series 1 was used to detect the influence of triclosan, solvents, impregnation time, and the presence of hydrogel coating on the interval to catheter blockage by P. mirabilis biofilm. The experiments with test series 2 focused on the dynamic interaction of the hydrogel coating and biofilm formation. The division of the catheterized bladder model into 3 sampling zones brought more information about the spatial segregation of the bacterial population.

Results

The bacteriostatic efficiency of the water-soluble polyhexamethylene biguanide and polyvinylpyrrolidone iodine complex was limited to the first hours after catheterization. Only catheters containing triclosan resisted encrustation for significantly longer (up to >7 days). In contrast, the uncoated and hydrogel-coated catheters were occluded by day 2.

Conclusions

The hydrogel layer can increase aggregation of the planktonic cells and newly nucleated crystals, leading to even faster catheter blockage than in the case of uncoated silicone. However, the addition of active agents were able to suppress this negative effect.