Kinetics of <i>Staphylococcus epidermidis </i>Clearance from the Peritoneal Catheter Site of Renal Failure Mice following Intracatheter Inoculation

Abstract

A mouse model of surgically induced renal failure harboring a peritoneal catheter implant was utilized to study the response to intracatheter (IC) peritoneal inoculation of 10⁶ or 10⁸ colony-forming units (CFU) Staphylococcus epidermidis. The kinetics of bacterial clearance from peritoneal structures, including the peritoneal catheter implant, was investigated in renal failure and sham-operated mice. All animals survived experimental challenge with 10⁶ CFU; however, microbiological assessments conducted 1 week and 1 month after inoculation revealed that the catheter site of a small number of renal failure mice was persistently colonized. During 1 month following 10⁸ CFU IC inoculation, significant animal mortality was observed in renal failure mice (29.4%), while sham-operated controls presented minimal lethality (5.9%). In surviving mice of both groups, the peritoneal catheter site proved to be a reservoir for persisting S. epidermidis, a finding confirmed by scanning electron microscopy. Throughout the study, local and systemic inflammatory responses were comparable in sham-operated and renal failure mice. Nevertheless, 3 and 4 weeks after 10⁸ CFU inoculation, S. epidermidis recovery was significantly greater in sham-operated controls. Phenotypic colonial variation was observed in a majority of S. epidermidis isolates, and only in those specimens recovered 2 or more weeks after inoculation. Our results reveal that the peritoneal catheter implant provides a preferred site for persistent bacterial colonization up to 1 month after inoculation.