THE EFFECT OF UREASE INHIBITORS ON THE ENCRUSTATION OF URETHRAL CATHETERS

Encrustation and blockage of indwelling urethral catheters is primaril y brought about by infection of the urinary tract by Proteus mirabilis or other urease-producing species. The bacteria colonise the catheter forming a biofilm community within a polysaccharide matrix. The activ ity of the urease drives up the urinary pH and causes the crystallisat ion of calcium and magnesium phosphates in the biofilm. We have used a simple physical model of the catheterised bladder to investigate the ability of urease inhibitors to control encrustation. It was observed that acetohydroxamic acid (1.0 mg/ml) and fluorofamide (1.0 mu g/ml) r estricted the increase in pH of P. mirabilis-infected urine from 9.1 t o 7.6. Significant reductions in the deposition of calcium and magnesi um salts were also recorded on the silicone catheters. Electron micros copy confirmed that encrustation and occlusion of the catheter lumen w as minimal in the presence of the urease inhibitors. The data from thi s in vitro study suggests that urease inhibitors, particularly fluorof amide, could have clinical applications in the prevention of catheter encrustation and blockage.