1229. Two-Step Water Filtration and Control of Delftia acidovorans Hemodialysis Pseudo Outbreak

Background Reverse Osmosis (RO) technology improved the quality of water needed for hemodialysis (HD). Guidelines require low colony count (<100 cfu/ mL) in product water used for HD. It is not unusual to see occasional water cultures above the maximum allowable count. In this event the RO machine is pulled out of service, disinfected and returned to service only after repeat culture is negative Methods In our institution, we had positive water culture from RO machine over a year duration that became persistently positive. Identification of the bacteria revealed Gram-negative environmental water cultures Delftia acidovorans. Despite all attempts to contain the pseudo outbreak (no clinical cases), all the RO were persistently positive. Renovation and replacement of all RO machines with Heat disinfection RO machines were performed. Results Delftia acidovorans grew from disinfection line, pump and product water were highly related using whole-genome sequencing. City water cultures were directly cultured repeatedly negative, and only after large volume filtration cultures grew Delftia. Despite the renovation, many machines were turning positive again. Two-step water filtration at the incoming water to the HD suite, was extremely effective in maintaining all water cultures negative for over 2 years after the pseudo outbreak. Conclusion Delftia Is a waterborne pathogen that is capable of forming a biofilm. 2-Step filtration (with 4 micron and less than a micron) is an expensive and effective way to improve the incoming water quality. Heat disinfection RO has a lower risk for development of a biofilm as compared with chemical disinfection RO. Disclosures All authors: No reported disclosures.