Preliminary evaluation of silver-coated peritoneal catheters in rats

Silver is known to have powerful antibacterial properties against a variety of micro-organisms and has a low toxicity and a favorable biocompatibility profile. This study was designed to evaluate the effectiveness of silver-coated catheters in preventing early exit-site infection and to assess tunnel morphology. Seven male Sprague-Dawley rats underwent simultaneous implantation of two double-cuffed, silver-coated silicone rubber and standard silicone rubber catheters. Weekly observations and photographs documented exit-site characteristics. The animals were sacrificed and catheters removed and processed for histopathology of the external tunnel at 5 weeks. Exit sites of silver-coated catheters tended to have less inflammation and infection and healed better than those of uncoated catheters; however, these data did not achieve significance using the Wilcoxon signed-rank test. Sections of the external tunnel of well-healing exit sites showed an epithelialized tract with granulation tissue near the cuff and significant invasion of the external cuff by collagen with a mild neutrophilic inflammatory response. In contrast, the histology of the external tunnel of infected exists revealed exudate overlying inflammatory granulation tissue and a variable degree of fibrosis of the cuff. When the exit sites appeared similar, no significant histopathological differences in sinus tract and cuff morphology were noted with either silver or standard catheters. In conclusion, these findings suggest that silver coating of catheters may decrease the incidence of early exit-site infections and allow better ingrowth of the catheter.