A Study on Microbial Culture Level of Hemodialysis Water Under the Influence of Disinfection Loop Types
Ok Lae Park,Head nurse, AKU, Wonkwang University School of Medicine & Hospital
Muyung Seak Yang,Assistant Professor, Department of nursing, Jesus University
Seon Ho Ahn,Professor, Department of Internal Medicine, Wonkwang University School of Medicine
Purpose: The purpose of this study was to analyze the culture level of microorganism in hemodialysis water that is affected by disinfection loop types and temperature difference. Method: This retrospective study was performed between January 2010 and December 2014 in our hospital dialysis unit. We consecutively used (1) A method: monthly chemical disinfection, (2) B method: a combination of weekly 90℃ heat disinfection (maintaining hot water ≥ 90℃ entering the dis tribution loop) and bimonthly chemical disinfection and (3) C method: a combination of weekly 95℃heat disinfection (maintaining hot water ≥ 85℃ returning from the distribution loop) and bimonthly chemical disinfection while checking bacterial count and endotoxin level every 4 weeks. Results: The endotoxin levels at all sampling points of the water treatment system were lower than 0.005/ ml throughout the study. Bacterial counts were consistently <100 CFU/ ml except sometimes in A and B method. It is noteworthy that the application of weekly heat and bimonthly chemical disinfection reduced bacterial levels to acceptable levels, but an escape phenomenon of microbial growth was noted in B method. Bacterial growths were 28.31±123.13, 19.58±112.31 and 0.65±9.83 CFU/mL in A, B and C method, respectively. Bacterial growths in C method was significantly decreased than in A and B method (p<0.001). In Logistic regression analysis by disinfection method, bacterial contamination risk of dialysis water was associated with A (OR 33.151 p<0.001) and B (OR 19.107 p<0.001) disinfection method when compared with C disinfection method Conclusions: This study suggests that it is more important to maintain 85℃returning water temperature from the distribution loop than entering water temperature into that in disinfection of the RO water
Piping, Dialysis water, microbial Quality, Chemical disinfection, Thermal disinfection
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