Controlling Legionella in Hospital Drinking Water: An Evidence-Based Review of Disinfection Methods
YUSEN LIN, JANET E. STOUT, VICTOR YUCAMBRIDGE UNIVERSITY PRESS, INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, FEBRUARY 2011 IntroductionThis study reviewed the efficacy of different disinfection methods for controlling Legionella in hospitals, including copper-silver ionization, chlorine dioxide, hyperchlorination, monochloramine, UV, point-of-use filtration, and superheat-and-flush. The four criteria each disinfection method must meet to validate efficacy include: ResultsA summary of findings for each disinfection method is included below. Copper-silver ionization– Only method validated by the four criteria– Easy installation and maintenance– Not impacted by higher temperatures– Residual levels are maintained for a prolonged period– Efficacy declines in pH greater than 8.5 Chlorine dioxide– Penetrates biofilm– Effective over a wide range of pH levels– Creates harmful byproducts– Difficult to maintain residual levels Monochloramine– Penetrates biofilm– Effective over a wide range of pH levels– Can cause anemia in dialysis patients– On-site generation can be complicated Hyperchlorination– Most expensive and unreliable of all methods– Causes corrosion– Does not penetrate biofilm– Introduces carcinogens into the water Point-of-use filtration– Effective against Legionella and Mycobacterium– Provides immediate protection making them a good option for outbreaks– Not cost-effective for long-term use UV– Non-chemical– Works best when installed on the incoming water supply– Does not provide systemic disinfection Superheat-and-flush– Effective in emergencies– Not effective for prolonged use– Limited to hot water lines ConclusionThere are several viable methods for controlling Legionella, but copper-silver ionization was the only method validated by the four criteria at the time of this study. The researchers concluded that “copper-silver ionization appears to be the best available technology today for controlling Legionella colonization in hospital water systems.” They suggested that rigorous maintenance plans, regular monitoring of ion concentrations, and frequent Legionella testing are necessary to ensure long-term success. Full report
Controlling Legionella in Hospital Water Systems: Experience With the Superheat-and-Flush Method and Copper-Silver Ionization
JANET E. STOUT, YU-SEN E. LIN, ANGELLA M. GOETZ, ROBERT R. MUDERCAMBRIDGE UNIVERSITY PRESS, INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, DECEMBER 1998 IntroductionThis study evaluated the efficacy of superheat-and-flush and copper-silver ionization for Legionella control in an acute care hospital. The hospital had been using the superheat-and-flush method for 13 years but was still experiencing incidences of Legionnaires’ disease. ResultsLegionnaires’ cases decreased once the copper-silver ionization system was installed, with no cases reported in the last year evaluated by the study (1997). The average number of Legionnaires’ cases from 1979 to 1996 are included below. ConclusionCopper-silver ionization was found to be more effective in controlling Legionella than superheat-and-flush. The study notes that hospitals must conduct routine Legionella testing and closely monitor ion concentrations for copper-silver ionization to remain effective. Full study
