A study of domestic and hospital drinking water found Legionella, the bacteria that causes Legionnaire’s disease, in 41% of samples. Flinders University Researchers made a critical connection between the pathogen’s co-existence and a ‘host’ microorganism in all tested samples.
The study found Legionella bacteria “infect the amoeba host and then once inside these hosts are protected from disinfection strategies,” says Flinders University Associate Professor of Environmental Health Harriet Whiley, a co-author of the new journal article in Water Research.
Legionnaires’ disease is a severe pneumonia-like infection that poses a significant risk to elderly and immunocompromised people.
“It is vital that we strive to improve the management of our water distribution systems, particularly in high-risk settings such as hospitals, to protect vulnerable populations,” says Associate Professor Whiley.
The findings support the need for further research to investigate the prevalence of Legionella and free-living amoebae in domestic and commercial water systems and to improve guidelines to better control water systems and safeguard public health.
“Free-living amoebae are ubiquitous in the environment and cause both opportunistic and non-opportunistic infections in humans. Some amoebae are the natural reservoirs of opportunistic plumbing pathogens, such as Legionella pneumophila,” says Flinders University PhD candidate Muhammad Atif Nisar, who conducted the study.
“There is a need for future research to improve disinfection strategies against amoeba to reduce their colonisation within building drinking water systems.”
Up to 75% of the drinking water or biofilm samples tested positive for free-living amoebae. This included V. vermiformis, which was present in 55% of samples, and Acanthamoeba was present in 11%.
As well as being hosts for Legionella, Acanthamoeba and V. vermiformis are pathogens that can cause severe eye infections, with contact lens users and immunocompromised individuals at greatest risk.
The water samples were collected from showers and hand basins in domestic houses and hospitals across New South Wales and South Australia.
“Future water management protocols should incorporate improved treatment strategies to control amoebae to reduce the risk to end-users,” adds Mr Atif Nisar.
Text by: Flinders University
