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
Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks Following Various Disinfection Procedures
ISABELLA MARCHESI, GRETA FERRANTI, ANTONELLA MANSI, ANNA M. MARCELLONI, ANNA R. PROIETTO, NAVNEET SAINI, PAOLA BORELLA, ANNALISA BARGELLINIAMERICAN SOCIETY FOR MICROBIOLOGY, APPLIED AND ENVIRONMENTAL BIOLOGY, MAY 2016 IntroductionThis study evaluated four disinfection methods for their efficacy in controlling Legionella and their corrosive effects on water pipes. The four methods included: ResultsLegionella controlOf the four disinfection methods analyzed, monochloramine had the lowest Legionella positivity rate (percentage of test sites positive for Legionella), followed by chlorine dioxide, hydrogen peroxide, and heat. None of the methods eliminated Legionella. The results from the lowest Legionella positivity rate (most effective) to the highest (least effective): CorrosionHydrogen peroxide and chlorine dioxide caused pitting on the pipe’s interior surface. Pitting is a type of corrosion that can lead to holes. Monochloramine and heat appeared to be less aggressive, with monochloramine exhibiting uniform corrosion with the rare formation of pitting. Heat showed corrosion similar to that observed on the untreated samples. ConclusionContinuous chemical disinfection is effective to an extent and is significantly more effective than using only heat, and each modality displayed different morphologies of corrosion. Full report
