Urease-induced precipitation of phosphate salts in vitro on indwelling catheters made of different materials.

The urease-induced precipitation of phosphate salts on indwelling catheters was studied in an experimental in vitro model. The precipitation was strongly pH-related and was much higher in synthetic urine than in human urine. In the latter, it was significantly lower on silicone catheters than on latex catheters, including those with a hydrophilic coating. The precipitation on silicone catheters that had been in situ was not increased as compared with that on unused catheters, in contrast to latex catheters with a hydrophilic coating, among which the precipitation on used catheters was higher.