Something in the Water: Preventing Legionnaires' Disease at Hospitals

A recent CDC report found that five primarily waterborne diseases, including Legionnaires' disease, cost the United States $970 million annually between 2004 and 2007, based on data from a large insurance claims database. Legionella grows in hot water and causes legionellosis, or Legionnaires' disease. The bacteria have been found in hospitals' water systems, which puts patients at risk for infection. In fact, a study in Infection Control and Hospital Epidemiology linked a hospital's decorative fountain to an outbreak of Legionnaires' disease. John Marx, MPH, an infection control practitioner and microbiologist at the University of Wisconsin Hospital in Madison, describes how his hospital eliminated Legionella by treating its water system.

Case study: University of Wisconsin Hospital
Legionnaires' disease is "one of these problems that people don't think about quite so much," Mr. Marx says. "People are concerned about C. diff, MRSA, multi-drug resistant organisms — and they are huge problems — but you can't ignore [Legionnaires' disease] completely."

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More than 15 years ago, the University of Wisconsin Hospital had some cases of Legionnaires' disease that were linked to the water system. To prevent further infection, the hospital analyzed different methods to eradicate Legionella from the hospital's water. One method the hospital tried was hyperchlorination, which adds high levels of chlorine to the water for several hours. While this method reduced Legionella at first, the effects were short-lived.  

Another option was installing a system that would add copper and silver ions to the water. In this technique, a vessel in a section of a pipe continuously releases copper and silver ions into the water as the water flows past, distributing the ions throughout the hospital's water system.  

While this option seemed promising, at the time CDC did not have official guidelines or recommendations regarding the practice because it was relatively new. This lack of guidance was one of the biggest challenges in trying to implement the technology to prevent Legionella infections, Mr. Marx says. However, as the other options were only short-term, the hospital ultimately decided to try the new technology. Mr. Marx says he anticipated the copper and silver ions would reduce Legionella slowly over time. After the first two weeks, however, the count was already down by 99 percent. The hospital has not been able to culture Legionella from its hot water system in more than 10 years.  

3 Steps to implement a copper/silver ion system
Mr. Marx shares the following steps for hospitals to implement a copper and silver ion system as part of its infection control efforts.

1. Perform a risk assessment. Hospitals should first assess the risk of having cases of  Legionnaires' disease. This assessment should include culturing the water in different areas of the hospital, because the flow pressure and temperature are different depending on the pipe's location. Mr. Marx found low flow areas, particularly within one large intensive care unit, were more likely to have high levels of Legionella. In addition, because ICU patients are more vulnerable physically, they are more likely to contract Legionnaires' disease if the bacteria are in the water. Transplant patients and other immuno-compromised patients are also high risk; hospitals should focus culturing the water in those patients' units. A hospital that does not perform transplants is at a lower risk. "If there are no transplant patients or long-term patients, hospitals should take that into account because [the copper and silver ion system] is an investment," Mr. Marx says.

Hospitals should also evaluate the current evidence and literature, including CDC recommendations, on Legionella.  

2. Place the device for maximum effect.
Hospitals should place the device at the front end of the hot water distribution system to ensure the ions are distributed to all hospital areas served by the water supply. The flow should also be moderate, because very high flow areas can erode the device faster. Most hospitals disperse copper and silver ions only in the hospital's hot water supply, because Legionella typically do not grow in cold water.

3. Test the water. The hospital will need to periodically test the level of copper and silver ions in the water as well as monitor for the density of Legionella. At the University of Wisconsin Hospital, plant engineering staff test for copper weekly to ensure the system continues to release the correct level of ions. If the level of copper is correct, the amount of silver is most likely also appropriate. To verify the proportion is correct, the University of Wisconsin Hospital tests silver annually. Initially, the hospital also tested for Legionella monthly.

Once the system is in place and water cultures for Legionella verify that it is functioning effectively for an adequate period of time, hospitals may be able to reduce the frequency of culturing to quarterly or twice a year, according to Mr. Marx. More frequent cultures are not necessary as correct copper levels usually indicate that the system is working and Legionella is effectively suppressed. In the event of unexpected disruption of the system, cultures should be used to verify Legionella control after the system is back on line, Mr. Marx says.

More Articles on Legionnaires' Disease:

Paul Levy: Water Interests in Hospitals: Spraying Infections?
Outbreak of Legionnaires Disease Linked to Hospital's Decorative Fountain

Study Finds Testing Guidelines for Community-Acquired Legionella Inadequate

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