CONTROLLING LEGIONELLA USING COPPER-SILVER IONIZATION

Hospital-acquired Legionnaires' disease, associated with contaminated hot water plumbing systems, is a well-documented problem in hospitals and may also be a problem in nursing homes. In this study, four nursin g homes were surveyed to determine the extent to which potable hot wat er systems were colonized by Legionella pneumophila and to measure mic robial and chemical factors related to legionellae contamination. The survey indicated that: two of the homes were heavily contaminated with Legionella and suggested that contamination is associated with hot wa ter temperatures, chlorine concentrations, the presence of free-living amoebae, possibly intermittent seeding of building plumbing systems w ith legionellae from the public water supply. The most heavily coloniz ed nursing home plumbing system was then equipped with a copper-silver ionization device, designed to control Legionella. A subsequent two-y ear evaluation indicated that the device controlled Legionella but not amoebae or non-Legionellaceae bacteria, Maintenance of the ionization system and. monitoring of legionellae and metals concentrations in th e water are important for effective use of the control device.