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


retrofitted these newly purchased 12-pound ice machines with silver-impregnated components. These field-tested machines performed better than expected (Table 1). Ice machines with silver-impregnated components then became commercially available, and 2 new silver-impregnated 12-pound ice machines were purchased for the HSCT unit. To minimize bacterial growth in the water pipes, polycarbonate tubing was replaced with copper tubing in the DWIMs and their con- nection tubing wherever possible. Copper-tubing supply con- nections to the DWIMs alone did not have a large impact, and high HPCs were observed. In total, 5 DWIMs were flushed to run more water through


the HSCT unit plumbing. A continuous flow drain was installed for flushing the water lines feeding DWIMs 1 and 2 on the BMT unit at 5.7 L (1.5 gallons) per minute. Because drinkingwater and ice from theDWIMwere not being used by


patients, simulations of ice machine usage on the unit via flushing was initiated to produce a more accurate result from the water tests related to our trial interventions. In addition to the continuous flow drain, engineering staff


using different water filters. Pre- and postfilter ports were used to collect samples to determine filter performance. The greatest reduction in HPC was observed with the 0.005-µm filter (Table 1). An additional combination intervention includedUV germicidal irradiation and ozone disinfection. The UV treat- ment occurred at the point of use, and the ozone device was added to treat the ice in the ice bin. Results are shown in Table 1 and Figures 2–5. DWIM cleaning and sanitizing procedures were audited by


an outside vendor. We learned that our DWIM cleaning was excellent. Cleaning was performed every 6 months following the manufacturer’s instructionswith the exception of installing new 0.005-µm filters every 6 months. Culturing of the DWIM prior to the manufacturer’s recommended cleaning schedule showed high HPCs in the ice machine bin and reservoir, suggesting that routine cleaning practices may not reduce the HPCin theDWIMto acceptable levels for safe consumption of ice by HSCT patients. For machine 1, the UV/ozone disinfection intervention


flushed the ice and water from theDWIM twice per day, which entailed dumping the ice bin and flushing the drinking water for 3 minutes. Water was cultured before and after water filtration


reduced 30-second water HPCs to very low levels. This inter- vention also brought reduced the HPCs of first-drop water below goal levels; however, HPCs were higher in first-drop water than in 30-second water. This machine had been fitted


figure 2. Drinking water and ice machine (DWIM) 1 water and ice. Heterotrophic plate counts (HPCs; CFU/mL) and effects from interventions.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136