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


figure 4. Dendogram for environmental and case-patient isolates collected during a Pseudomonas aeruginosa outbreak in a neonatal intensive care unit. Dendogram displays the pulsed-field gel electrophoresis (PFGE) patterns obtained from select environmental and case- patient isolates. Groupings identified by related PFGE patterns are labeled at the right side of figure.


dence that POU filters interrupted this P. aeruginosa outbreak in the short term, consistent with published literature.28,29 Although a single study determined that POU filters are the most economical means of protecting vulnerable hospital patients from waterborne pathogens,30 others caution against


Continuous education of healthcare personnel, auditing, and feedback about adherence to hand-hygiene policies were recommended. Staff hands could have also been indirectly contaminated with P. aeruginosa through touching sink basins or nearby shelves. Although colonized staff have been implicated in transmission of P. aeruginosa in previous out- breaks,7,26,27 we did not find an association between specific staff members and cases. Our epidemic curve and case-control study provide evi-


Environmental Protection Agency standards for safe drinking water32) and no Pseudomonas. Cultures of postfilter water should be negative. During the following months, the hospital followed these recommendations and continued additional water remedia- tion efforts, including decontamination of faucets and drains, routine flushing of faucets, hot water flushing of the hospital water system, hyperchlorination, monitoring temperature and water flow variability, and continuous supplemental chlorine dioxide. Despite remediation, prefiltered water samples continued to grow P. aeruginosa, although levels declined. Postfilter water samples were negative. From January to November 2015, 8 new cases of


their use as a long-term solution.31 We recommended POU filtration continue until P. aeruginosa is no longer detected in the hospital water. We recommended validation of remedia- tion measures through monthly microbiologic testing of prefiltered water and validation of the POU filters by testing postfilter water monthly before the scheduled replacement of the filter. The goal of remediation was total heterotrophic plate counts ≤500 CFU/mL (in accordance with


P. aeruginosa occurred in NICU patients, representing an increase over baseline, with 1 death. The hospital continued to work closely with the state health department during this time; CDCwas periodically consulted. In response to these cases, the hospital hired outside experts to direct water remediation. We continued to recommend regular testing of postfilter water to ensure proper filter function and strict adherence to infection control measures until eradication of P. aeruginosa could be maintained. The reasons for continued cases was unknown,


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