Prevention of Legionnaires' disease in hospitals.

BACKGROUND The first instance of Legionella infection in a Norwegian hospital was confirmed in 2005. We describe the best-known methods of eradicating Legionella in hospitals. MATERIALS AND METHOD The article is based on the authors' experience of measures to prevent Legionnaires' disease in hospitals and on a non-systematic search in PubMed. RESULTS There are several methods of combating Legionella in hospitals. These include chlorination, heat treatment, and the use of filters. However, recontamination easily re-occurs after eradication. The silver and copper ionisation treatment of water is a well-documented method for the systematic and long-term eradication of Legionella in water. The disadvantages of this method are that it is expensive, that there is a risk of discolouring the water, and that there is a possibility of developing resistance in environmental bacteria. This resistance mechanism can theoretically be transferred to bacteria that cause illness. INTERPRETATION We recommend the silver and copper ionisation treatment of water as a method of preventing nosocomial Legionnaires' disease when standard methods fail and there is a high prevalence of Legionella in the water. The discolouration of operation instruments that occurs as a result of high silver concentrations can be avoided by using a separate water supply for operation units.