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.