A novel rabbit model for the evaluation of biomaterial associated urinary tract infection.

OBJECTIVES: It was the objective of this study to establish an animal model which simulates the conditions of a biomaterial associated bacterial urinary tract infection. METHODS: The curled portion of polyurethane double pig-tail ureteric stents, pre-coated with P. aeruginosa,were inserted transurethrally into the bladder in eight rabbits. Eight control animals received sterile stent material. Microbiology studies of the stent, bladder tissue, and urine, as well as bladder histopathology were evaluated. RESULTS: P. aeruginosa was recovered from all stent, bladder, and urine specimens in the P. aeruginosa pre-coated stent group, and no P. aeruginosa was present in any of the control specimens (p=0.0002). The controls only developed minimal bladder inflammation, whereas the bladders of the P. aeruginosa pre-coated stent group were significantly more inflamed (p<0.01). CONCLUSIONS: This rabbit model was easy to manipulate, low in maintenance requirements, and had pathophysiologically distinct end points, suitable for the assessment of biomaterial associated urinary tract infections.

Antimicrobial activity of a novel catheter lock solution.

Intravascular catheter-associated bloodstream infections significantly increase rates of morbidity and hospital costs. Microbial colonization and development of biofilms, which are known to be recalcitrant to antibiotic therapy, often lead to the loss of otherwise patent vascular access systems. We evaluated a new taurolidine- and citrate-based catheter lock solution (Neutrolin; Biolink Corporation, Norwell, Mass.) for its activity against planktonic microbes, antimicrobial activity in a catheter model, and biofilm eradication activity. In studies of planktonic microbes, after 24 h of contact, 675 mg of taurolidine-citrate solution per liter caused > 99% reductions in the initial counts of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Entercoccus faecalis. A solution of 13,500 mg/liter was cidal for Candida albicans. Ports and attached catheters inoculated with 50 to 600 CFU of these bloodstream isolates per ml were locked with heparin or the taurolidine-citrate solution. After 72 h, there was no growth in the taurolidine-citrate-treated devices but the heparin-treated devices exhibited growth in the range of 6 x 10(2) to 5 x 10(6) CFU/ml. Biofilms were developed on silicone disks in modified Robbins devices with broth containing 6% serum (initial counts, 10(6) to 10(8) CFU/cm(2)). The axenic biofilms were treated for 24 h with taurolidine-citrate or heparin. Taurolidine-citrate exposure resulted in a median reduction of 4.8 logs, whereas heparin treatment resulted in a median reduction of 1.7 logs (P < 0.01). No significant differences in the effects of the two treatments against P. aeruginosa and C. albicans were observed. These findings suggest that taurolidine-citrate is a promising combination agent for the prevention and treatment of intravascular catheter-related infections.