Legionella pneumophila — a type of bacteria that incites a form of pneumonia known as Legionnaires' disease — thrives in warm tap water installations where dissolved organic matter is prevalent, which supports the growth of biofilm, according new research published in Applied and Environmental Microbiology.
For the study, researchers created a model drinking water system to measure the growth and formation of biofilm and Legionella in drinking water not treated with disinfectant. Using this system, researchers were able to compare simulations of a water supply with a high concentration of dissolved organic matter to that with a low concentration.
"Drinking water prepared from aerobic groundwater with a low concentration of dissolved natural organic matter induced a very low biofilm concentration that did not support growth of L. pneumophila," said lead study author Dick van der Kooij, PhD, former principal microbiologist at KWR Watercycle Research Institute in Nieuwegein, Netherlands. "Drinking water from two other sources with higher concentrations of organic matter induced higher biofilm concentrations that supported Legionella growth."
According to the CDC, approximately 5,000 Legionnaires' cases are reported in the United States annually. One in 10 of those infected will die.
Contaminated water has been attributable to multiple healthcare-associated outbreaks in recent history. In September 2016, five patients at University of Washington Medical Center in Seattle contracted Legionnaires' as a result of the presence of Legionella bacteria in the hospital's water supply. Two of those infected died.
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