Heat exchangers installed by hospitals to conserve energy can promote growth of Legionella pneumophila in their hot water systems, according to a study published in Infection Control & Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.
For the study, researchers followed two cases of healthcare-associated Legionella infections at a 400-bed hospital in Canada. They identified the hot water system as the source of contamination.
The study found 27 of 34 water samples collected from taps showed high levels of the Legionella bacteria. Also, seven out of eight samples taken directly from the heat exchanger had high levels of the bacteria. The heat exchanger that was used to pre-heat the water "acted as a reservoir for Legionella pneumophila and contributed to the systemwide contamination that led to the cases," the study authors noted.
Heat exchangers are typically installed to conserve energy. Researchers suggest performing an infection risk assessment on energy recovery devices in hot water systems.
"Because these units can act as incubators for pathogens in hot water systems, the operation and maintenance of heat exchanges need to be reviewed to minimize these risks and prevent future outbreaks," said Michele Prevost, PhD, the study's principal investigator.
The Canadian hospital in question decided to remove the system altogether after the investigation.
"No energy or water savings are worth a life," Louis Valiquette, MD, chief of microbiology at the Quebec-based University of Sherbrooke, said.
Legionella pneumophila can cause severe respiratory infections, like Legionnaires' disease, in people with weakened immune systems.