AN IMPROVED MODEL FOR BACTERIAL ENCRUSTATION STUDIES

A comparative evaluation of various biomaterials for their resistance to bacterial colonization and encrustation in infected urine is an imp ortant area in urological biomaterials research. This article describe s an in vitro dynamic perfusion system that allows four reactors conta ining 24 1-in. catheter samples (6 per reactor) to be simultaneously p erfused at a constant flow rate by synthetic urine. A common urease-pr oducing urinary pathogen, Proteus mirabilis, was maintained at a level of 10(6) colony-forming units/mL for 7 days in the dynamic perfusion reactors. The pH and bacterial population were monitored every 24 h an d the percentage of encrustation on latex and hydrogel-coated commerci al catheter materials gave reproducible results in three different run s, 15.2 +/- 3.65% and 13.8 +/- 2.58%, respectively. A major issue of i nlet clogging due to ascending bacteria or ammonia has been rectified using a dismountable inlet assembly. An incubator coupled with a cooli ng system allowed accurate temperature maintenance of 37 degrees C in all four reactors. Results from scanning electron microscopy of some l atex samples are also presented. (C) 1995 John Wiley & Sons, Inc.