Efficacy of point-of-entry copper–silver ionisation system in eradicating Legionella pneumophila in a tropical tertiary care hospital: implications for hospitals contaminated with Legionella in both hot and cold water

• Published in: The Journal of hospital infection 2008-02, Vol.68 (2), p.152-158
• Main Authors: Chen, Y.S, Lin, Y.E, Liu, Y.-C, Huang, W.K, Shih, H.Y, Wann, S.R, Lee, S.S, Tsai, H.C, Li, C.H, Chao, H.L, Ke, C.M, Lu, H.H, Chang, C.L
• Format: Article
• Language: English
• Subjects: Academic Medical Centers; Bacterial diseases; Bacterial diseases of the respiratory system; Biological and medical sciences; Copper; Cross Infection - epidemiology; Cross Infection - prevention & control; Disease Outbreaks - prevention & control; Environmental Monitoring; Epidemiological Monitoring; Epidemiology. Vaccinations; General aspects; Hospital infection control; Human bacterial diseases; Human viral diseases; Humans; Infection Control - instrumentation; Infection Control - methods; Infectious Disease; Infectious diseases; Ions; Legionella; Legionella disinfection; Legionella pneumophila; Legionella pneumophila - growth & development; Legionella pneumophila - isolation & purification; Legionnaires' Disease - epidemiology; Legionnaires' Disease - prevention & control; Medical sciences; Point-of-entry ionisation; Silver; Taiwan - epidemiology; Temperature; Viral diseases; Viral diseases of the respiratory system and ent viral diseases; Water Microbiology; Water Purification - instrumentation; Water Purification - methods
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2007.10.020

Summary A medical centre in Southern Taiwan experienced an outbreak of nosocomial Legionnaires' disease, with the water distribution system thought to be the source of the infection. Even after two superheats and flush, the rate of Legionella positivity in distal sites in hospital wards and intensive care units (ICUs) was 14% and 66%, respectively. Copper–silver ionisation was therefore implemented in an attempt to control Legionella colonisation in both hot- and cold-water systems. Environmental cultures and ion concentration testing were performed to evaluate the efficacy of ionisation. When the system was activated, no significant change in rate of Legionella positivity in the hospital wards (20% vs baseline of 30%) and ICUs (28% vs baseline of 34%) of the test buildings over a three-month period was found, although all Legionella positivity rates were below 30%, an arbitrary target for Legionnaires' disease prevention. When ion concentrations were increased from month 4 to month 7, however, the rate of Legionella positivity decreased significantly to 5% (mean) in hospital wards ( P = 0.037) and 16% (mean) in ICUs ( P = 0.037). Legionella positivity was further reduced to 0% in hospital wards and 5% (mean) in ICUs while 50% sites were still positive for Legionella in a control building. Although Legionella was not completely eradicated during the study period, no culture- or urine-confirmed hospital-acquired Legionnaires' disease was reported. Ionisation was effective in controlling Legionella for both hot and cold water, and may be an attractive alternative as a point-of-entry systematic disinfection solution for Legionella.