Initial comments: This blog discusses an outbreak of Legionella at the Veterans Administration (VA) Pittsburgh Healthcare System (University Drive Campus, in Oakland).

I.  Background: On November 16, 2012, the Pittsburgh Tribune reported that at least 4 patients at the Veterans Administration Pittsburgh Healthcare System’s University Drive Campus (in Oakland) had recently developed pneumonia caused by Legionnaires’ disease.

Click here to read the Pittsburgh Tribune’s article entitled “Oakland VA patients diagnosed with pneumonia caused by Legionnaires’ disease.”

II. This Outbreak’s Source: According to this news report, restrictions on the use of this hospital’s water began last Friday, and hospital workers began distributing bottled water to patients and visitors.

CBS News (2-5-2013): “CDC report reveals breakdowns in handling of deadly outbreak at VA hospital.”

The hospital also states that “the source of the infection” has been traced to the hospital’s water distribution system, prompting the hospital to improve this system’s method of disinfection. The hospital added that “our existing copper-silver ionization system, which reduces the presence of Legionella in water, may not be as effective as previously thought, as is the case in other health systems using this method.” The hospital, therefore, will now employ a chlorination system “to ensure better control.”

III: Notes about Legionella: Legionella is the genus of the bacterium responsible for this cluster of true infections. Whether the species responsible for this VA hospital’s outbreak is Legionella pneumophilia is unclear.

Legionella thrive in water systems that provide surfaces in the healthcare setting for its concentrated bacterial growth. These systems include air-conditioning systems, cooling towers, hot tubs, waterlines, ice machines, steam towel warmers, and electronic faucet components.

A water wall in a hospital’s lobby (in Wisconsin) and a contaminated hospital decorative water fountain (in Maryland) have also been linked to two outbreaks of Legionnaires’ disease, which can be fatal. Read about the second outbreak in Maryland by clicking here.

IV. Mode of transmission: Likely, the 4 patients of this VA hospital became infected following their inhalation of (i.e., the direct contact of their lungs with) small droplets of contaminated water (or, possibly, via their aspiration/choking while drinking contaminated water). The transmission of this bacterium is reportedly limited to the environment-to-patient route; its transmission via the patient-to-patient route has not been documented.

But, infection can also occur by modes other than the inhalation of contaminated water droplets (or via aspiration).

Specifically, this newspaper article about these 4 infections at this VA hospital (in Oakland) does not exclude the possibility that this outbreak’s mode of transmission was a contaminated reusable medical device, such as a bronchoscope or respiratory therapy equipment: (a) that might have been properly (or improperly, for that matter) disinfected, but that was terminally rinsed with potable water contaminated with Legionella; and (b) was used on patients while the device was still wet with water.

The findings of a Veterans Affairs Inspector General investigation were published in April, 2013. <Click here> to read it.

V. Literature: While this newspaper article reports that this cluster of 4 patients is a “true” outbreak, several reports in the literature document “pseudo-outbreaks” of healthcare-associated Legionnaires’ disease. For example:

~1~ REPORT #1: The CDC published a report “Pseudo-Outbreak of Legionnaires Disease Among Patients Undergoing Bronchoscopy — Arizona, 2008,” which can be read by clicking here.

According to this report by the CDC, “non-sterile ice used to cool saline-filled syringes for bronchoalveolar lavage was the likely source of Legionella contamination of these clinical specimens. Ice was supplied by two ice machines, which became contaminated by heavy Legionella colonization within the center’s potable water supply during a 6-month period (February–July 2008).”

Further, this report states that a copper-silver ionization system that the hospital had installed to prevent Legionella growth in the potable water system “might have provided false assurances for Legionella control.” Interestingly, the VA hospital within the Pittsburgh Healthcare System that reported the cluster of 4 Legionella infections (see above) similarly stated that its existing copper-silver ionization system may not have been ineffective.

Read Dr. Muscarella’s blog that distinguishes between a “pseudo” and “true” outbreak by clicking here.

~2~ REPORT #2: Schuetz et al. (2009) report an investigation that found the ice machine in a bronchoscopy suite to be contaminated with Legionella pneumophilia (serogroup 8). According to this report, patients were exposed to this bacterium as a result of staff having directly immersed uncapped syringes of sterile saline in contaminated ice baths during the procedures.

Read: Schuetz et al. Pseudo-outbreak of Legionella pneumophilia serogroup 8 infection associated with a contaminated ice machine in a bronchoscopy suite. Infect Control Hosp Epidemiol; 2009 May;30(5):461-6.

~3~ REPORT #3: Mitchell et al. (1997) report an investigation that traced the source of a pseudo-outbreak of Legionella pneumophilia to contaminated tap water used to rinse disinfected bronchoscopes.

Read:  Mitchell DH, Hicks LJ, Chiew R, et al. Pseudoepidemic of Legionella pneumophilia serogroup 6 associated with contaminated bronchoscopes. J Hosp Infection 1997 Sep;37(1):19-23.

VI. Recommendations:

  1. Ensure adherence to environmental controls to prevent the colonization and proliferation of Legionella on those surfaces within the healthcare setting that have been linked to Legionnaires’ disease.
    • For example, as has been previously reported by the Veterans Affairs Office of Inspector General (click here) to control the transmission of Legionella in the healthcare setting, perform the following measures, as required:
      • turn off decorative fountains and whirlpool spas;
      • install point of use filters for fauce
        ts and shower heads;
      • restrict patient showering and drinking of hospital water (provide bottled drinking water); and
      • hyperchlorinate (≥ 2 ppm) all water and flush at distal sites and/or perform a super heat (160-170 degrees) and flush of all pipes to point of use for a minimum of ten minutes.
        • Further, if environmental cultures are positive for Legionella, all healthcare-associated pneumonia patients should be tested for Legionella infection.
  1. Ensure the proper reprocessing of reusable instruments – particularly of bronchoscopes, respiratory therapy equipment, nebulizers that deliver medications and other aerosol generating devices – that may infect the lungs, if they are not properly reprocessed.
  • Ensure that these instruments are dry before their reuse, even if the water used to rinse them following their chemical immersion was filtered.
  • Maintain any bacterial filters that are used to improve the quality of the water used to rinse such instruments.
  1. Consider maintaining more enhanced infection controls and measures of surveillance to prevent Legionnaires’ infection in healthcare settings.
  • As required, consider sampling environmental surfaces, including the medical facility’s potable water supply (e.g., performing such semi-annual testing in areas where care is provided to the most susceptible patients, including oncology patients and hematopoietic stem-cell recipients).
  1. If using a copper-silver ionization system to reduce the presence of Legionella in the hospital’s water, ensure the adequacy of this system’s effectiveness.
  2. Ensure ice machines are properly cleaned and their water filters are replaced as recommended by their respective manufacturer, especially those ice machines used in a bronchoscopy suite.
  3. Use only sterile fluids for filling or for reprocessing respiratory care equipment. (If tap water is used for rinsing during its reprocessing, ensure the instrument is terminally dried.)
  4. [One report suggestions either not using steam towel warmers, or requiring that these devices be routinely drained, cleaned and dried. (See: Higa et al. Legionella pneumophilia contamination in a steam towel warmer in a hospital setting. J Hosp Infect 2012 Mar;80(3):259-61.)]
  5. Additional recommendations are provided in a report by the Veterans Affairs Office of Inspector General (April 23, 2013) and may be read by <clicking here>.

Blog by: Lawrence F. Muscarella, Ph.D. updated on 2-6-2013

3 thoughts on “Prevention of Legionnaires’ Disease in Healthcare Settings”
  1. I believe this problem will only grow as more immunocompromised patients enter the general population. is there a fast and reliable test of water systems for legionella?

    1. Dear Mr. Beal, Thank you for your comment. Commerical legionella testing services are available. Entitled “Procedures for the Recovery of Legionella from the Environment,” the CDC published in 2005 a manual that describes procedures to process environmental samples obtained during investigations of legionella outbreaks. This manual discusses how to collect water samples and prepare them for bacteriologic examination. For example, this manual recommends that 1 (one) liter of water be collected, although larger volumes of water (1 to 10 liters) may be needed to detect legionella in water that has very low concentrations of these bacteria such as municipal water supplies. If a liter cannot be collected from a sample source, a smaller volume is acceptable. (Note: If the water source has been recently treated with chlorine, add 0.5 ml of 0.1N sodium thiosulfate to each 1 liter sample to neutralize the disinfectant.) Also according to this CDC manual, “swabs of faucet aerators and shower heads should be taken before water samples from these sites.” THe manual adds that: “the sample should be taken with the aerator or shower head removed if possible. Polyester swabs with wooden shafts work well for this purpose. The swabs should be submerged in 3-5 ml of water taken at the same time to prevent drying during transport.”

      This CDC manual can be read on-line at:

      Other references of interest include:
      1. Barabee, J.M., G.W. Gorman, W.T. Martin, B.S. Fields, and W.E. Morrill. 1987. Protocol for sampling environmental sites for Legionellae. Appl Environ. Microbiol. 53:1454-1458.
      2. Lee S, Lee J. Outbreak investigations and identification of legionella in contaminated water. Methods Mol Biol. 2013;954:87-118. doi: 10.1007/978-1-62703-161-5_5.
      3. Haupt TE, Heffernan RT, Kazmierczak JJ, et al. An outbreak of Legionnaires disease associated with a decorative water wall fountain in a hospital. Infect Control Hosp Epidemiol. 2012 Feb;33(2):185-91. Epub 2011 Dec 23.
      4. Krøjgaard LH, Krogfelt KA, Albrechtsen HJ, et al. Detection of Legionella by quantitative polymerase chain reaction (qPCR) for monitoring and risk assessment. BMC Microbiology 2011, 11:254 (Pages 1-7). READ this article at:
      Response by: Lawrence F Muscarella PhD

  2. Muirsis is a company that has developed a faucet for the Healthcare Industry. This electric faucet flushes itself every six hours at a 1.5 gpm to prevent high level bacteria build up, such as legionnaires disease. Muirsis Faucet can be used as an automatic faucet to conserve water or a continuous water flow with the ability to change both water temperature and water flow completely hands free to reduce Hospital Acquired Infection and promote better Hand Hygiene. As the healthcare Industry does not use an Aerator because of the airborne bacteria and stagnant water, Muirsis provides standard an Anti- Splash adaptor to reduce splash and all Muirsis Faucets come with a pre-installed Flow Regulator. Please feel free to check out the web-site, we would love to hear your feedback.

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