NDT Advance Access published online on September 3, 2008
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfn485
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A novel bio-assay increases the detection yield of microbiological impurity of dialysis fluid, in comparison to the LAL-test
1 Department of Internal Medicine, Renal Division, Ghent University Hospital, Gent, Belgium 2 Departement of Nephrology and Intensive Care Medicine, Charité-Virchow-Klinikum, Humboldt Universität zu Berlin, Berlin 3 EXcorLab GmbH, Obernburg, Germany
Correspondence and offprint requests to: Griet Glorieux, Renal Division, University Hospital Gent, De Pintelaan 185, 0K12IA, B-9000 Gent, Belgium. Tel/Fax: +32-9-332-45-11; E-mail: griet.glorieux{at}UGent.be
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Abstract |
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Background. Biological purity of dialysis water is considered as one of the primary conditions to deliver optimal haemodialysis.
Methods. The present study explores the added value of a novel cytokine (IL-1ß) induction assay, using a monocytic THP-1 cell line, compared to the classical detection methods for microbial dialysis fluid contaminants.
Results. In contrast to the Limulus Amebocyte Lysate (LAL)-test, which only detects intact lipopolysaccharide (LPS), the THP-1 assay was also sensitive to peptidoglycan, short bacterial DNA fragments and LPS fragments <5 kD. The purity of 269 dialysis fluid samples was tested by the THP-1 assay and compared to the LAL-test. Two hundred and sixty samples complied with the definition of ‘pure’ dialysis fluid as laid down in the European Pharmacopeia (European Best Practice Guidelines for Hemodialysis. Section IV. Dialysis fluid purity. Nephrol Dial Transplant 2002; 17: 45–62) but 27 of these so-called pure dialysates (10.3%) provoked a pro-inflammatory response in the THP-1 assay. Furthermore, among the 230 samples that complied the definition of an ultrapure dialysis fluid, 21 samples (9.1%) were pro-inflammatory. These data illustrate that this novel bio-assay detects microbiological entities with an inflammatory potential that cannot be found by the classical LAL screening method.
Conclusions. Adding this novel THP-1 assay to the classical methods will be helpful in the prevention of biofilm formation in the delivery system and should have relevance by more accurate detection of dialysate contamination, hence decreasing micro-inflammation in the haemodialysis patient.
Keywords: bio-assay; dialysis fluid quality; haemodialysis; LAL-test
* Both authors contributed equally to this work.
Received for publication: 12. 2.08
Accepted in revised form: 5. 8.08