Full text loading...
Chapter 80 : Eleven Years of Experience with Novel Strategies for Legtonella Control in a Large Teaching Hospital
The Queen's Medical Centre (QMC) is a large teaching hospital housing approximately 1,400 beds. Each block has its own independent circulating hot water system (HWS). The West Block and Medical School have storage calorifiers (water heaters) equipped with antistratification pumps, and the water is circulated at 60 to 62№C. The circulation of hot water at 60№C so that it is delivered to every outlet at 50№C within 1 min of opening is the recommended strategy for the control of Legionella in the United Kingdom. A number of problems are associated with the installation of thermostatic mixer valves (TMVs). They are expensive to purchase; require much maintenance, particularly if the water is hard; and the failure of the nonreturn valves fitted within them can result in cold water passing into the hot or vice versa, depending on the relative pressure differences. At the end of March 2000, the cold water supply to the ward was equipped with a chlorine dioxide dosing system, which ensures that a chlorine dioxide residual of at least 0.5 mg/liter reaches beyond the TMV to the shower hose and head. To date, this does not appear to have significantly reduced the legionellae. It may be that legionellae can only be maintained at undetectable levels by routinely removing and disinfecting the TMVs and shower components. To enable this, the units would have to be designed for quick release so that they can be rapidly recycled.
Key Concept Ranking
- Restriction Fragment Length Polymorphism