Quantitative microbiological monitoring of hemodialysis fluids: evaluation of methods and demonstration of lack of test relevance in single-pass hemodialysis machines with automatic dialysate proportioning with reverse osmosis-treated tap water

Abstract
Two methods for estimating the quantity of microorganisms present in hemodialysis fluid, a blood agar surface-spread plate method and a total-count water tester device impregnated with modified standard plate count agar, were evaluated. Both methods exhibited comparable precision; colony counts obtained with the total-count water tester were consistently and unacceptably low. The need for routine quantitative microbiological monitoring of hemodialysis fluids such as that recommended by the American Public Health Association was not supported by the results of this study. Such testing was not of value in predicting untoward reactions for patients undergoing hemodialysis, nor did quantitative testing of hemodialysis fluids identify the buildup of potentially hazardous levels of contamination within hemodialysis systems. The kinds of organisms found im hemodialysis systems, i.e., gram-negative water-borne bacilli, were elucidated.