Preventing Legionnaires’ Disease in Healthcare Facilities Part 1: This 5-Part Program Helped Us Maintain the Safest Environment for Our At-Risk Patients

Posted on by CDC's Safe Healthcare Blog
John Letson
John Letson, Vice President Plant Operations, Memorial Sloan Kettering Cancer Center

Guest Author: John Letson, Vice President Plant Operations, Memorial Sloan Kettering Cancer Center

Since being discovered, Legionnaires’ disease continues to make vulnerable populations sick with severe pneumonia. This month’s Vital Signs report focuses on the continued rise of Legionnaires’ disease in the U.S., deficiencies in environmental control that have led to outbreaks, and how these deficiencies can be prevented with Legionella water management programs based on newly published standards. Healthcare and infection control professionals, with the support of facilities managers, are in a unique position to reduce the risk for Legionella growth and spread in their facilities and ensure patients are properly tested for Legionnaires’ disease.

Incidence of Legionnaires’ disease in the U.S. increased nearly 300% from 2000 through 2014. People are usually infected by inhaling aerosolized water containing Legionella bacteria. Hotels, long-term care facilities and hospitals are common settings for outbreaks of Legionnaires’ disease. In these types of facilities, potable water, cooling towers, and other water systems like decorative fountains are likely sources of infection. Exposure sources in healthcare facilities can also include areas like hydrotherapy and because patients may have problems swallowing, the contamination of ice machines can put them at increased risk for Legionella acquisition through aspiration.

The increasing incidence of Legionnaires’ disease is likely underestimated because clinicians may not suspect this disease, causing many cases to go undiagnosed. Along with testing patients with severe pneumonia, clinicians should test patients with healthcare-associated pneumonia for Legionnaires’ disease using both a Legionella urinary antigen test and a culture from a lower respiratory secretion on selective media. Lower respiratory specimen cultures are particularly important because they are necessary to link any cultures of Legionella from water sources to the clinical cases, thereby identifying the source responsible for outbreaks.

Testing patients with healthcare-associated pneumonia is especially important when other patients with Legionnaires’ disease have been identified at the facility, no matter where they acquired the infection. Further, any positive environmental tests at the facility, or, any changes in water quality such as low chlorine levels that may lead to Legionella growth should renew emphasis on testing susceptible patients.

Collaboration is key. Infection control professionals should work with facility workers and managers to determine how their building is at an increased risk for growing and transmitting Legionella and then develop and use a Legionella water management program. A toolkit, released in conjunction with the Vital Signs report, is available to support development and implementation of such a program for healthcare facilities. Being alert and proactive is necessary to ensure protection of our patients, many of whom are at an increased risk for developing severe disease if infected with Legionella. 


Memorial Sloan Kettering Cancer Center (MSK) has a 470 inpatient bed hospital, outpatient clinics, and research facility headquartered on the upper east side of Manhattan, with additional outpatient treatment centers in Brooklyn; Long Island; Westchester County, New York; and New Jersey. The well-being of our patients is the primary concern of all doctors, nurses, and staff.

The threat of waterborne pathogens, primarily Legionella, varies based on patient population and the level or type of exposure. Some of the at-risk populations include the elderly, patients with respiratory issues, and those with suppressed immune systems. The risk level is amplified for those with combinations of these factors, with the highest level of risk being among in-patients who might take showers. The greatest threat is for patients who are immunocompromised, either by diseases or medicines; these represent the majority of patients at MSK.

The way that MSK has consistently maintained the safest environment for our at-risk patient population has been by maintaining our five part program. The five part program consists of copper-silver ionization systems, chemical water treatment contracts, MSK staff monitoring, third party water testing for Legionella, and most of all a zero tolerance for Legionella in any of our water systems. We have developed this risk based, dynamic, and successful methodology for regular testing of potable water storage tanks, random distal sites, and cooling towers throughout the in-patient facility and where applicable throughout the enterprise. The testing frequencies and associated water systems did not all come about as one singular global policy or plan. MSK’s plan was in place long before ASHRAE 188, the new industry standard, was even considered. Instead we methodically went through each water system over time and identified whether or not those systems presented any risk, both perceived and evidence-based, and developed testing strategies to consistently monitor and mitigate pathogens if necessary. MSK’s monitoring program continues to evolve over time as the culture testing results establish patterns of increased levels of positive Legionella activity with changing environmental dynamics. The release of ASHRAE 188 and now the CDC’s toolkit on Developing a Water Management Program will help healthcare institutions to each develop their own unique and site specific plan. 

Stay tuned for my blog post to learn more about MSK’s experiences and long term remediation approach later this week.

Posted on by CDC's Safe Healthcare Blog

5 comments on “Preventing Legionnaires’ Disease in Healthcare Facilities Part 1: This 5-Part Program Helped Us Maintain the Safest Environment for Our At-Risk Patients”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    We are just getting started on a program similar to yours and was wondering if there was any way I could get a look at your program? Thank you,

    hello, I am recently was involved in an investigation and I wanted to get some clarification from you in regards to the following: (1) The ice machine had a domestic type of filtration system that completely removes chlorine, (2) the filter however does not remove anything smaller than .5 micrometers in size., (3) the ice and water is given the all types of patients including immune compromised patients. (I don’t have the specification for the filter on hand.) (4) the facility feels Legionnaire will not survive ice cold conditions.

    My question and please verify if the ice machine should maintain a chlorine residual at all times and what is that level? We had a total of 4-5 deaths. Thank you,

    This is a very informative article. It has led me to have physician test my husband’s sputum to determine if indeed he had the Legionella bacteria. He went from having pneumonia in lower right lobe of lung and a dry cough with 102 temperature to a deep, gut wrenching cough during which clear sputum followed by super thick white or yellow sputum came up. He nearly strangles on it. He is a dialysis patient. Had his flu shot and had his pneumonia vaccine within past five years. After sitting in an old church building during funeral and having a vent across from us blow cold air into his nose and throat, he get super sick with this cough and it has persisted for nearly two weeks. He is getting no more that three hours of sleep each night.

    Is there anyway all cases of pneumonia be routinely tested for legionnaires? I think the number of cases would increase. I would also like all cruise ships to be routinely tested as they are also a likely candidate.

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Page last reviewed: June 17, 2016
Page last updated: June 17, 2016