In a dialysis plant supplied with inverse osmosis and subjected to regular periodical disinfection procedures, using four different monitors: Monitral SC AFB, Fresenius 2008 E, Bellco Multimat and Gambro AK 10, the variations in microbiological characteristics of the dialysis water were examined along the circuit from inverse osmosis to the transformation into dialysate. With the first three monitors, fitted with ultrafilters in polyamide (Diaclear), polysulphone (Diasafe) and polysulphone Amicon (Multiclean), the study was carried out at the end of the 2nd hour of hemodialysis (HD), during the 10th, 20th, 30th and 40th HD sessions after changing of the filter, while with the fourth monitor, not fitted with an ultrafilter, it was carried out at the end of the 2nd hour during three distinct HD sessions. Test samples were obtained from the outflow of the inverse osmosis, at the monitor entry point and on the dialysate at the exit points both from the monitor and from the ultrafilters. Furthermore, the sterility of the concentrate was also ascertained at the end of the 2nd hour of HD during each test. Overall: 1) the treated water was found to be invariably bacteriologically sterile and LAL negative at the outflow from the inverse osmosis; 2) at entry to the monitor, although the water was bacteriologically sterile, some samples were LAL positive; 3) at the exit from the monitor, despite the ascertained sterility of the added concentrate, the dialysate was always LAL positive, associated with the presence of colony forming units in only two HD sessions; 4) after treatment by the ultrafilters, in the three monitors fitted with these, the dialysate was invariably sterile and LAL negative. In conclusion, the results of our study reveal the internal hydraulic circuit of the monitor to be the principal source of endotoxin contamination of the dialysate and provide some evidence that ultrafilter systems are able to retain endotoxins and/or fragments of LPS present in the dialysate.
|Number of pages||7|
|Journal||Giornale italiano di nefrologia : organo ufficiale della Società italiana di nefrologia|
|Publication status||Published - 1996|
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