Treatment of a Legionella pneumophila-colonized water distribution system using copper-silver ionization and continuous chlorination

The detection in April 1997 of a case of nosocomial legionellosis in our ho spital led to the discovery that both our hot- and cold-water circuits were heavily colonized with Legionella Pneumophila. Conventional methods for er adication of the organisms were unsuccessful, so a copper-silver (Cu-Ag) io nization system and a continuous chlorination system were installed. Five m onths later, the number of colonized sites decreased from an initial 58.3% to 16.7% (Infect Control Hosp Epidemiol 1999;20:426-428).