798 infection control & hospital epidemiology july 2017, vol. 38, no. 7


figure 4. Drinking water and ice machine (DWIM) 3 water and ice. Heterotrophic plate counts (HPCs; CFU/mL) and effects from interventions.


investigations of floor plumbing diagrams, we discovered that patient floor plumbing was designed to mitigate low-water- pressure problems. Cross connections formed a loop to alleviate pressure issues. Cross-connected sections can remain stagnant or neutral, making disinfection more difficult. Hospital designers installed larger-capacity DWIMs so that


nurses would have access to ice and water close to patients. The unintended consequence was decreased water and ice usage per machine. Stagnant water and ice promoted RGM growth greater than that observed in the old hospital, thus putting pediatric HSCT patients at risk. Our goal was to achieve a safe bacterial level (<500CFU/mL) in water and ice to allow our HSCT patients to use the DWIMs again. Several variables likely affected the ice HPCs: water source,


volume used, plumbing design, and materials. Becausemore ice was produced and held in the ice machine, we postulated that water and ice were held for longer periods, thereby promoting increased growth of RGM. A temperature tracking device placed inside the DWIM showed temperatures from 21.1°C to 33.3°C (70°F to 92°F) inside the DWIM, surrounding the area where water is held prior to making ice, and this is an optimal growth temperature for RGM.10 The current HPC for US water was established using


48-hour incubation. RGM grow more slowly than gram- negative bacteria, requiring longer incubation times to become


visible. The HPCs were the same at 48 hours as at 5 days, but stereoscopic efforts were required because they cannot be seen with the naked eye. We noted that RGM appeared on culture plates after 5 days of incubation. A collaborative effort is needed to determine the level of sanitization forDWIMproduction of ice and water required to meet the safety needs of severely immunocompromised patients. The focus needs to extend beyond Legionella as a waterborne pathogen and needs encompass all waterborne pathogens, such as RGM.11 Also, water treatment with chloramination while decreasing Legionella, may increase RGMs in potable water and may change the microflora and biofilms of water distribution systems.11,12 The American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers (ANSI/ASH- REA) Standard 188, initially established to regulate minimum legionellosis risk management requirements for building water systems, has changed the emphasis for hospital administrators, who should now be concerned about all microbial content (ie, all genus/species) in water used in health care.11 In summary, HSCT patients were vulnerable to acquiring


RGM colonization and infection from ingesting water and ice with high HPCs from the potable water system. We succeeded in reducing water HPCs to acceptable levels. Despite our interventions, however, we could not consistently achieve goal


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