Quality standards for water and concentrate used to produce dialysate are well established. The European Renal Association standard stipulates that microbiological contamination of the delivered water should comply with the recomendations of the European Pharmacopoeia bacterial count of – 100 colony-forming unit/ml and endotoxin content of -0.25 endotoxin unit/ml. All convective methods require ultrapure water (endotoxin level < 0.03 endotoxin unit/ml). Regular monitoring of water quality, preferably monthly, should be performed. Ultrapure dialysate is defined as a bacterial count <0.1 colony-forming unit/ml and an endotoxin level <0.03 endotoxin unit/ml. This endotoxin level is the sensitivity treshold for the simplest of the limulus amoebocyte lysate assays.
Bacterial products, such as endotoxins, fragmen of endotoxin, peptidoglycans, and fragments of bacterial DNA, can cross the pores into the blood stream. These are all potent inducers of cytokynes and stimulators of the acute phase response contributing to chronic inflammation. Recently, circulating endotoxins have been shown to have potential impact on survival in patients undergoing peritoneal dialysis or hemodialysis. The introduction of ultrafiltered dialysate was associated with a significant reduction in plasma ß2-microglobulin concentration and a significant improvement in nutritional status, assessed by plasma albumin concentration and creatinine generation rate as marker of muscle mass,