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Environmental Validation of Legionella Control in a VHA Facility Water System

  • Chetan Jinadatha (a1), Eileen M. Stock (a2), Steve E. Miller (a3) and William F. McCoy (a4)

Abstract

OBJECTIVES

We conducted this study to determine what sample volume, concentration, and limit of detection (LOD) are adequate for environmental validation of Legionella control. We also sought to determine whether time required to obtain culture results can be reduced compared to spread-plate culture method. We also assessed whether polymerase chain reaction (PCR) and in-field total heterotrophic aerobic bacteria (THAB) counts are reliable indicators of Legionella in water samples from buildings.

DESIGN

Comparative Legionella screening and diagnostics study for environmental validation of a healthcare building water system.

SETTING

Veterans Health Administration (VHA) facility water system in central Texas.

METHODS

We analyzed 50 water samples (26 hot, 24 cold) from 40 sinks and 10 showers using spread-plate cultures (International Standards Organization [ISO] 11731) on samples shipped overnight to the analytical lab. In-field, on-site cultures were obtained using the PVT (Phigenics Validation Test) culture dipslide-format sampler. A PCR assay for genus-level Legionella was performed on every sample.

RESULTS

No practical differences regardless of sample volume filtered were observed. Larger sample volumes yielded more detections of Legionella. No statistically significant differences at the 1 colony-forming unit (CFU)/mL or 10 CFU/mL LOD were observed. Approximately 75% less time was required when cultures were started in the field. The PCR results provided an early warning, which was confirmed by spread-plate cultures. The THAB results did not correlate with Legionella status.

CONCLUSIONS

For environmental validation at this facility, we confirmed that (1) 100 mL sample volumes were adequate, (2) 10× concentrations were adequate, (3) 10 CFU/mL LOD was adequate, (4) in-field cultures reliably reduced time to get results by 75%, (5) PCR provided a reliable early warning, and (6) THAB was not predictive of Legionella results.

Infect Control Hosp Epidemiol 2018;39:259–266

Copyright

Corresponding author

Address correspondence to William F. McCoy, PhD, Phigenics, LLC, Nevada Center for Applied Research, University of Nevada MS-0525, 1664 N Virginia St, Reno, NV 89557 (wmccoy@phigenics.com).

References

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1. Veterans Health Administration (VHA). Prevention of healthcare-associated Legionella disease and scald injury from potable water distribution systems. VHA Directive 1061. Washington, DC: Department of Veterans Affairs, Veterans Health Administration; 2014.
2. McCoy, WF, Downes, EL, Lasko, TM, Neville, MJ, Cains, MF. A new method to measure viable Legionella and total heterotrophic aeriobic bacteria. J Cool Tower Inst 2009;30:1432.
3. McCoy, WF, Downes, EL, Leonidas, LF, et al. Inaccuracy in Legionella tests of building water Systems due to sample holding time. Water Res 2012;46:34973506.
4. McCoy, W, Rosenblatt, A. HACCP-based programs for preventing disease and injury from premise plumbing: a building consensus. Pathogens 2015;4:513528.
5. ANSI/ASHRAE Standard 188: Legionellosis: Risk Management for Building Water Systems. ASHRAE website. https://www.ashrae.org/resources--publications/bookstore/ansi-ashrae-standard-188-2015-legionellosis-risk-management-for-building-water-systems. Published 2005. Accessed January 8, 2018.
6. Centers for Disease Control and Prevention. Procedures for the recovery of Legionella from the Environment. Atlanta, GA: National Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases, Respiratory Diseases Laboratory Section; 2005.
7. International Standards Organization. Water quality: detection and enumeration of Legionella , ISO 11731 Geneva, Switzerland: International Organization for Standardization; 1998, updated in 2017.
8. Zhou, Y, Benson, JM, Irvin, C, Irshad, H, Cheng, Y. Particle size distribution and inhalation dose of shower water under selected operating conditions. Inhal Toxicol 2007;19:333342.
9. World Health Organization. Legionella and the prevention of Legionellosis. Geneva, Switzerland: WHO Press; 2007.
10. Fitzgeorge, RB, Baskerville, A, Broster, M, Hambleton, P, Dennis, PJ. Aerosol infection of animals with strains of Legionella pneumophila of different virulence: comparison with intraperitoneal and intranasal routes of infection. J Hyg (Lond) 1983;90:8189.
11. Berendt, RF, Young, HW, Allen, RG, Knutsen, GL. Dose-response of guinea pigs experimentally infected with aerosols of Legionella pneumophila . J Infect Dis 1980;141:186192.
12. Bauer, M, Mathieu, L, Deloge-Abarkan, M, et al. Legionella bacteria in shower aerosols increase the risk of Pontiac fever among older people in retirement homes. J Epidemiol Commun Health 2008;62:913920.
13. Armstrong, TW, Haas, CN. Legionnaires’ disease: evaluation of a quantitative microbial risk assessment model. J Water Health 2008;6(2):149166.
14. Buse, HY, Schoen, ME, Ashbolt, NJ. Legionellae in engineered systems and use of quantitative microbial risk assessment to predict exposure. Water Res 2012;46:921933.
15. Schoen, ME, Ashbolt, NJ. An in-premise model for Legionella exposure during showering events. Water Res 2011;45:58265836.
16. Castellino, LM, Gamage, SD, Hoffman, PV, et al. Healthcare-associated Legionnaires’ disease: limitations of surveillance definitions and importance of epidemiologic investigation. J Infect Prevent 2017;18:307310.
17. Lucas, CE, Taylor, TH, Fields, BS. Accuracy and precision of Legionella isolation by US laboratories in the ELITE program pilot study. Water Res 2011;45:44284436.
18. Garrison, LE, Kunz, JM, Cooley, LA, et al. Vital signs: deficiencies in environmental control identified in outbreaks of Legionnaires’ disease—North America, 2000–2014. MMWR Morb Mortal Wkly Rep 2016;65:576584.
19. Developing a water management program to reduce Legionella growth and spread in buildings: a practical guide to implementing industry standards. Centers for Disease Control and Prevention website. http://www.cdc.gov/legionella/maintenance/wmp-toolkit.htmL. Published 2016. Accessed January 8, 2018.

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