13 May 2014 | Research News | Commentary

UPMC Presby, a Pittsburgh-based hospital, recently made headlines by announcing three Legionnaires' disease cases (including one death) in 2013 were a result of exposure to Legionella in ice machines. The staff tracked down the source after learning that the only exposure to water for one of the patients was ice chips, who had aspirated (choked on an ice chip).

Legionella is among several bacteria that have been isolated from ice machine water dispensers and ice. While the presence of these bacteria in ice is generally not a significant risk for disease transmission, those who are severely ill, immunocompromised and bedridden are the most vulnerable. They are at a greater risk for aspiration-fluids entering the upper airway to the lung by way of choking or by micro-aspiration. Legionnaires' disease has been shown to occur following documented episodes of aspiration.

Research confirms ice machines as a potential source of exposure for some cases of Legionnaires' disease. Our 1985 study, showed that while ice dispensers are supplied with cold water, the condenser/compressor can heat the piping inside the machine and warm the cold water enough to support bacterial growth. The charcoal filter on the cold water line removes chlorine and can become colonized. That water is ultimately dispensed or made into ice. Most bacteria do not multiply in ice, but they can survive at these low temperatures.

While there is concern about any source of Legionella within healthcare facilities, the warm water distribution system remains the most significant source of exposure to Legionella. This should be the primary focus for infection control and Legionnaires' disease prevention.

Legionella Testing

Two circumstances would warrant testing of ice machines: 1) as part of a case investigation or 2) following cleaning/disinfection of the ice machine to demonstrate effectiveness of the preventive maintenance.

Sampling Instructions for Ice Machines

  • Use SPL sample bottles to scoop up ice. Two or three sample bottles of ice are needed so that the melted volume is at least 120 mL.  (Ice is processed in the lab after allowing it to melt and is concentrated by filtration.)
  • If a water dispenser is part of the machine, collect the water as you would from any faucet: turn on the faucet and immediately fill the sample bottle
  • A swab of the faucet opening can also be collected and is recommended if assessing the outlet as a source of infection during a case investigation.  
  • Shipping instructions see  Legionella testing

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