Peritonitis in peritoneal dialysis: bacterial colonization by biofilm spread along the catheter surface.

We have used modern techniques of direct microscopic examination and quantitative bacterial recovery to show the existence of a route of bacterial colonization along the external and internal surfaces of Tenckhoff catheters implanted in experimental animals. The external route of progressive bacterial colonization extends from the cutaneous exit site through the dacron cuff and into the peritoneum. Bacterial growth along this route consists primarily of glycocalyx enclosed bacterial biofilms adherent to catheter and tissue surfaces, and this surface colonization may or may not give rise to peritoneal infection in which free-living bacteria are found in the peritoneal fluid. The rate of this progressive bacterial colonization depends on the degree of bacterial contamination of the exit site at the time of implantation. Exit site sterilization (hibitane) delays the process while inoculation with rabbit skin strains of Staphylococcus epidermidis accelerates it. Even with optimal implantation techniques, bacterial colonization proceeds via this subcutaneous route so that most Tenckhoff catheter surfaces are covered with a bacterial biofilm, consisting predominantly of gram positive cocci, within three weeks after the implantation of these devices. The rate of bacterial biofilm development on both surfaces of these Tenckhoff catheters, the bacterial colonization of peritoneal tissues, and the dissemination of bacteria into the peritoneal fluid are all significantly accelerated by dialysis in this experimental animal model of continuous ambulatory peritoneal dialysis (CAPD).