Bacteriologically stressed animal model of new closed catheter drainage system with microbicidal outlet tube.

We have used a catheterized rabbit model to test a newly developed catheter drainage system that incorporates a microbicidal outlet tube. In these tests, this new system was compared with a currently marketed closed drainage system, with daily challenge at the outlet tube using an auxotrophically marked uropathogenic strain of Escherichia coli. In the control series (silicone catheter connected to a standard drainage bag via a tamper-evidence seal) the challenge organism developed upstream biofilm colonization of the luminal surfaces of the catheter and drainage system that was complete in 4.6 +/- 2.1 days in 11 animals, while in 1 animal a rapid overgrowth of the system with Streptococcus faecalis developed. The presence of organisms other than the marked E. coli strain on the luminal surfaces of these control catheters showed that down stream colonization was also operative. In the test catheter drainage series, the microbicidal outlet tube insert precluded upstream colonization by the challenge organism in 12 of 16 catheters and significantly delayed (7.2 +/- 1.0 days) this colonization in the remaining 4 animals. When upstream colonization by exogenous bacteria was precluded by this effective device, downstream colonization of the drainage system by mixed populations of bacteria that probably migrated into the bladder via the extraluminal urethral route developed in some animals (6 of 16).