Role of environmental surveillance in determining the risk of hospital-acquired legionellosis: A national surveillance study with clinical correlations

Janet E. Stout, Robert R. Muder, Sue Mietzner, Marilyn M. Wagener, Mary Beth Perri, Kathleen DeRoos, Dona Goodrich, William Arnold, Theresa Williamson, Ola Ruark, Christine Treadway, Elizabeth C. Eckstein, Debra Marshall, Mary Ellen Rafferty, Kathleen Sarro, Joann Page, Robert Jenkins, Gina Oda, Kathleen J. Shimoda, Marcus J. ZervosMarvin Bittner, Sharon L. Camhi, Anand P. Panwalker, Curtis J. Donskey, Minh Hong Nguyen, Mark Holodniy, Victor L. Yu, Sara Vaccarello, Asia Obman, Patricia Sheffer, Marcos Zervos, Mary Peri, Suzanne Pear, Sharon Camhi, Anand Panwalker, Gregory Harrington, Pat Jendryka, Douglas Kernodle, Audrey Hall, Sandy Garrott, Curtis Donskey, Christine Tredway, Liza Eckstein, Charolette Stecko, E. Gabriella Kehler, Dale Hamilton, Paul Myers, Roberta Messner, Nancy Coughlin, Kathleen Shimoda, Jeffrey Loutit, Kathryn Zink, Bruce Farber, Donna Armalino, Hong Nguyen, Denise Baker

Research output: Contribution to journalArticlepeer-review

100 Scopus citations


OBJECTIVE. Hospital-acquired Legionella pneumonia has a fatality rate of 28%, and the source is the water distribution system. Two prevention strategies have been advocated. One approach to prevention is clinical surveillance for disease without routine environmental monitoring. Another approach recommends environmental monitoring even in the absence of known cases of Legionella pneumonia. We determined the Legionella colonization status of water systems in hospitals to establish whether the results of environmental surveillance correlated with discovery of disease. None of these hospitals had previously experienced endemic hospital-acquired Legionella pneumonia. DESIGN. Cohort study. SETTING. Twenty US hospitals in 13 states. INTERVENTIONS. Hospitals performed clinical and environmental surveillance for Legionella from 2000 through 2002. All specimens were shipped to the Special Pathogens Laboratory at the Veterans Affairs Pittsburgh Medical Center. RESULTS. Legionella pneumophila and Legionella anisa were isolated from 14 (70%) of 20 hospital water systems. Of 676 environmental samples, 198 (29%) were positive for Legionella species. High-level colonization of the water system (30% or more of the distal outlets were positive for L. pneumophila) was demonstrated for 6 (43%) of the 14 hospitals with positive findings. L. pneumophila serogroup 1 was detected in 5 of these 6 hospitals, whereas 1 hospital was colonized with L. pneumophila serogroup 5. A total of 633 patients were evaluated for Legionella pneumonia from 12 (60%) of the 20 hospitals: 377 by urinary antigen testing and 577 by sputum culture. Hospital-acquired Legionella pneumonia was identified in 4 hospitals, all of which were hospitals with L. pneumophila serogroup 1 found in 30% or more of the distal outlets. No cases of disease due to other serogroups or species (I. anisa) were identified. CONCLUSION. Environmental monitoring followed by clinical surveillance was successful in uncovering previously unrecognized cases of hospital-acquired Legionella pneumonia.

Original languageEnglish (US)
Pages (from-to)818-824
Number of pages7
JournalInfection Control and Hospital Epidemiology
Issue number7
StatePublished - Jul 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Epidemiology
  • Microbiology (medical)
  • Infectious Diseases


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