Inaccuracy in Legionella tests of building water systems due to sample holding time

Water Research
William F McCoyMichael J Neville

Abstract

Most Legionella culture tests are performed on building water samples that have been shipped to analytical laboratories for analysis. Significant (≥ 1 log₁₀ unit) changes in results were observed in 52% of held samples (6 h or longer, ambient temperature) drawn from building water systems in a 42-sample initial survey. It was not practical to use the spread plate protocol for on-site "t = 0" cultures in a larger, more diverse survey of thousands of building water systems. Two thousand four hundred twenty-one (2421) building water samples were split for on-site analysis using a field culture protocol and then also cultured after overnight shipment to the lab for analysis with the standardized spread plate method. Legionella test results from building water system samples are usually interpreted as ≥ a numerical detection or action limit. Therefore, binary statistical analyses were calculated by setting t = 0 culture results to "true". Overall in this survey, 10.4% of water samples sent to the laboratory for analysis returned either false-positive or false-negative results. The overall positive predictive value of results was poor (36%). Most (83%) false-positive results were returned from utility water systems. Most (74%) false-...Continue Reading

References

Oct 9, 2003·Applied and Environmental Microbiology·Misty L PopeJon Standridge
Jun 15, 2007·Infection Control and Hospital Epidemiology : the Official Journal of the Society of Hospital Epidemiologists of America·Janet E StoutUNKNOWN Legionella Study Group

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Citations

Mar 4, 2014·Critical Reviews in Microbiology·Harriet Whiley, Michael Taylor
Dec 23, 2014·Emerging Infectious Diseases·Elyse FritschelDiana Cervantes
Apr 9, 2014·Infection Control and Hospital Epidemiology : the Official Journal of the Society of Hospital Epidemiologists of America·Dale A KrageschmidtWilliam F McCoy
Sep 10, 2014·Infection Control and Hospital Epidemiology : the Official Journal of the Society of Hospital Epidemiologists of America·Brian G Shelton
Oct 31, 2016·International Journal of Hygiene and Environmental Health·Thomas W LeibleinSusanne Hofer
Feb 6, 2018·Infection Control and Hospital Epidemiology : the Official Journal of the Society of Hospital Epidemiologists of America·Chetan JinadathaWilliam F McCoy
Jun 27, 2020·Journal of Water and Health·Katherine E FisherWilliam F McCoy
Apr 25, 2019·International Journal of Environmental Research and Public Health·Harriet WhileyRichard Bentham

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