669. A Large Legionnaires’ Disease Outbreak in a Hospital with a Legionella Disinfection System, Pennsylvania, 2011–2012
Session: Oral Abstract Session: HAI Outbreaks Crossing Healthcare Settings
Friday, October 4, 2013: 10:30 AM
Room: The Moscone Center: 300
Background: Healthcare-associated Legionnaires’ disease (LD) is a preventable form of pneumonia with a 30% case-fatality rate.  Centers for Disease Control and Prevention guidelines recommend maintaining a high index of suspicion for healthcare acquisition of Legionella. We characterized an outbreak’s extent and evaluated contributing factors in a hospital using copper-silver ionization, a method widely used to prevent Legionella growth in water.

Methods: Through medical chart review at a large, tertiary care hospital in an urban setting in November 2012, we identified patients diagnosed with LD during 2011–2012. Laboratory-confirmed cases were categorized as definitely, probably, and not healthcare–associated based on time spent in the hospital during the patients’ incubation periods. We performed an environmental assessment and collected environmental samples for Legionella culture. Clinical and environmental isolates were compared by sequence-based typing (SBT). Copper and silver ion concentrations were measured in 11 water samples.

Results: We identified five definitely and 16 probably healthcare-associated LD cases during 2011–2012; one definitely and four probably healthcare-associated case-patients died. Of 25 locations where environmental samples were obtained for Legionella-specific culture, all but one showed growth of Legionella; eleven isolates were identical to three available clinical isolates by SBT. Mean copper and silver concentrations were 0.30 and 0.02 parts per million, respectively; these were at or above the manufacturer’s recommended target for Legionella control. Despite this, all samples where copper and silver ion concentrations were tested showed Legionella growth.

Conclusion: The LD outbreak was linked to the hospital’s potable water system. The recommended copper and silver concentrations did not prevent Legionella growth in this system, which should prompt assessment of this technology’s effectiveness elsewhere. This outbreak also highlights the importance of maintaining a high index of suspicion for healthcare acquisition of Legionella even in the setting of a long-term disinfection program.

Alicia Demirjian, MD, MMSc1, Claressa Lucas, PhD1, Laurel Garrison, MPH1, Natalia Kozak, PhD1, Stanley States, PhD2, Ellen Brown, BS1, Jonathan Wortham, MD3, Amanda Beaudoin, DVM, PhD, DACVPM4, Megan Casey, RN, MPH5, Chandra Marriott, MPH6, Alison Ludwig, MD7, Ali Sonel, MD8, Robert Muder, MD9 and Lauri A. Hicks, DO1, (1)Centers for Disease Control and Prevention, Atlanta, GA, (2)Pittsburgh Water and Sewer Authority, Pittsburgh, PA, (3)Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, (4)Centers for Disease Control and Prevention; Pennsylvania Department of Health, Harrisburg, PA, (5)Allegheny County Health Department, Pittsburgh, PA, (6)Pennsylvania Department of Health, Pittsburgh, PA, (7)Office of Public Health Surveillance and Research, Department of Veterans Affairs, Palo Alto, CA, (8)VA Pittsburgh Healthcare System, Pittsburgh, PA, (9)VA Pittsburgh Healthcare System, University of Pittsburgh School of Medicine, Pittsburgh, PA


A. Demirjian, None

C. Lucas, None

L. Garrison, None

N. Kozak, None

S. States, None

E. Brown, None

J. Wortham, None

A. Beaudoin, None

M. Casey, None

C. Marriott, None

A. Ludwig, None

A. Sonel, None

R. Muder, None

L. A. Hicks, None

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