Investigation of the risk factors for development of infection by continuous ambulatory peritoneal dialysis patients

Chronic kidney disease is a progressive condition resulting in morbidity and mortality. Lost kidney function can be replaced by transplantation or dialysis (haemodialysis or peritoneal dialysis). Although peritoneal dialysis is simple and cheap, there are two major problems: protein loss and peritonitis. Despite protein supplements and aseptic technique, little is known about the correlation between protein loss and infection. The overall aim of this project was to characterise dialysate protein profiles of patients and investigate factors that might increase infection e.g. catecholamines. Protein profiles of daytime and overnight dwells were investigated using proteomic techniques: the total number of proteins in the dialysates was similar. Sequence analysis showed these were plasma proteins: e.g. albumin, fibrin-beta, IgG, complement C3 and transferrin. Three proteins not reported previously were detected: ceruloplasmin, albumin-myristate-azapropazone complex, and albumin-myristate-tri-iodobenzoate complex. Protein concentrations in overnight dwells were higher than in daytime samples. Differences were also found in other parameters, e.g. pH, glucose, and total iron. Direct measurements of ability of S. epidermidis to grow in peritoneal dialysates showed variation between patients. Addition of iron or catecholamines significantly increased growth, indicating dialysates were iron-limited. Analysis of dialysate exposure on S. epidermidis virulence showed that biofilm formation and haemolytic toxin production were significantly stimulated, but that stimulation varied between patients. One-year follow-up peritoneal dialysates showed that higher protein concentration occurred compared with initial dialysates. This may explain the apparent tendency of the one-year dialysate to sustain greater S.epidermidis growth. A correlation was found between dialysate protein concentration, and degree of growth stimulation/virulence. This suggests that a biomarker for infection risk in these patients could be protein concentration in their dialysate. Suggestions are made as to how this might be implemented into patient care.