Controlling Legionella in hospital water systems: experience with the superheat-and-flush method and copper-silver ionization.

Abstract

OBJECTIVE:

To evaluate the effect of copper-silver ionization on Legionella colonization and nosocomial legionnaires' disease and to compare the efficacy of metal ions versus the superheat-and-flush method of disinfection.

DESIGN:

Prospective determination over a 36-month period of copper and silver ion concentrations in the recirculating hot-water system, Legionella colonization of the hospital water distribution system, and cases of nosocomial legionnaires' disease. Retrospective comparison of results with the previous 13 years, during which the superheat-and-flush method was used.

SETTING:

The Pittsburgh Veterans' Affairs Health Care System (University Drive Division) acute-care hospital.

INTERVENTION:

Three copper-silver ionization systems were installed on the hot-water distribution system in November 1994.

RESULTS:

The average number of cases of legionnaires' disease per year and the percentage of distal sites positive for Legionella pneumophila for the superheat-and-flush method versus the copper-silver ionization method was six cases with 15% positivity versus two cases with 4% positivity, respectively. The reduction in Legionella colonization after copper-silver ionization was significant (P<.05) compared to the superheat and flush. Mean copper and silver ion concentrations (mg/L) were 0.29 and 0.054 from hot-water tanks, and 0.17 and 0.04 from distal outlets, respectively.

CONCLUSIONS:

We conclude that a properly maintained and monitored copper-silver ionization system was more effective than the superheat-and-flush method for reducing the recovery of Legionella from the hospital water distribution system.

• Authors: J E Stout, Y S Lin, A M Goetz, R R Muder
• Journal: Infection control and hospital epidemiology (Infect Control Hosp Epidemiol) Vol. 19 Issue 12 Pg. 911-4 (Dec 1998) ISSN: 0899-823X [Print] United States
• PMID: 9872527 (Publication Type: Journal Article)

Chemical References

• Ions
• Silver
• Copper

Topics

• Copper
• Cross Infection (epidemiology, prevention & control, transmission)
• Disinfection (methods)
• Heating
• Hospitals, Veterans
• Humans
• Infant, Newborn
• Infection Control (methods)
• Ions
• Legionella pneumophila (growth & development)
• Legionnaires' Disease (epidemiology, prevention & control, transmission)
• Maintenance and Engineering, Hospital (methods)
• Pennsylvania
• Retrospective Studies
• Silver
• Water Microbiology
• Water Supply