INTRODUCTION: To prevent hemodialysis-related infections, it is important to maintain hemodialysis system without microbial contamination. In May 2003, routine surveillance showed that dialysis water from dialysis port was contaminated with bacteria. To identify the causes of the contamination, we conducted an investigation as follows. METHODS: Patients undergoing dialysis were carefully monitored to see whether evidences of pyrogenic reactions or infections were present. Factors that could have influence on bacterial contamination in hemodialysis systems were thoroughly examined. In addition, microbiologic surveillances were done 7 times in 1 month. RESULTS: Although pyrogenic reactions or bacteremia did not occur, R. pickettii was repeatedly isolated above the Association for the Advancement of Medical Instrumentation (AAMI) standards from almost all dialysis units. Bacterial counts of specimens were higher in the proximal part of the water supply tube than the other parts in all dialysis machines. The colony count of R. pickettii exceeded the maximum level of technical limit in the specimens collected from the dialysis machines in the early morning after intermission of 48 hours. The structure of the supply tube was suspected as the origin of the colonization because stagnant water is a reservoir for bacterial multiplication. After remodeling the structure of the water supply tube, neither R. pickettii nor any other bacteria were isolated. CONCLUSION: Our investigation successfully identified the source of R. pickettii contamination of reverse osmosis water. Appropriate corrective measures for water distribution systems of hemodialysis center could prevent outbreak of dialysis-associated illnesses.
Bacteremia ; Bacteria ; Bacterial Load ; Colon ; Dialysis ; Humans ; Osmosis ; Ralstonia ; Ralstonia pickettii ; Renal Dialysis ; Water ; Water Supply