The quality of dialysate: an integrated approach

The role of bacterial contamination of dialysis water with respect to chronic inflammatory diseases associated with long-term hemodialysis therapy has been greatly underestimated in the last two decades. In the present article, recent multicenter studies assessing the bacteriological quality of water and dialysate are discussed. In addition, we describe that pyrogenic substances of bacterial origin derived from contaminated dialysate penetrate intact dialyzer membranes with the consequence of the induction of an inflammatory response in the patients. The influence of dialyzer membrane characteristics on the passage of bacterial substances from dialysate into blood are discussed. Reaching the patients blood, bacteria-derived substances activate circulating mononuclear cells to produce proinflammatory cytokines. Cytokines such as interleukin-1 beta and tumor necrosis factor-alpha are mediators of the acute phase response resulting in elevated levels of acute phase proteins (for example, C-reactive protein). The consequence is a state of microinflammation that may contribute to progressive inflammatory diseases in chronic renal failure such as beta2-microglobulin amyloidosis, protein catabolism, and atherosclerosis. The use of sterile dialysate reduces cytokine production and plasma levels of acute phase proteins, and may positively influence progressive inflammatory diseases in patients with end-stage renal failure.