Contributory factors in the development of infectious peritonitis in peritoneal dialysis patients

Peritoneal dialysis (PD) is the simplest and most economical therapeutic technique for renal failure patients. However, the percentage patients receiving PD in the UK has decreased since 2000 because of its potential complications, which primarily include protein loss and risk of infectious peritonitis. The latter issue in particular is a clinically significant condition contributing to the high mortality and morbidity rates observed in PD patients. Although some of the risk factors for PD-associated peritonitis have been identified, it is still unclear why certain PD patients are more susceptible than others to infection. The components of peritoneal dialysis fluid (PDF) were therefore examined to identify protein and hormonal factors that might increase PD-patient susceptibility to infection. Comprehensive characterisation studies were performed on initial and follow-up PDF samples collected from nine kidney failure patients. The data showed that staphylococci behaved differently in different PDF samples. Proteomic analysis identified an association between serum transferrin and infection risk, as transferrin in PDF was discovered to be significantly more iron-saturated than transferrin in the blood. Further, use of radioactive iron-labelled transferrin showed it could act as a direct iron source for the growth of peritonitis-causing bacteria. In addition, the catecholamine stress hormones noradrenaline and adrenaline were shown for the first time to be present in PDF and to be involved in modulating the growth of peritonitis-causing bacteria. Comparison studies between non-infected and infected PDF samples confirmed that the release of proteins, particularly transferrin, and catecholamines into the PDF were significantly higher during infection. Transferrin and catecholamines are therefore key indicators signaling the potential for bacterial growth in PDF. A test that detects increased levels of transferrin and catecholamines may therefore have value in predicting the likelihood of infection and thereby guide appropriate prophylactic treatment.