Hidden pathogens in hospital hot water systems

A new study by environmental health experts at Flinders University has found evidence of hospital water as a source of potential infection and even antimicrobial and multidrug-resistant organisms.

“Biofilms formed on taps, showers, drains and other outlets provide an ideal niche to harbour these dangerous antibiotic-resistant pathogens originating from the supply water or the human microbiota from washing contaminated hands,” said lead researcher Claire Hayward, from the Flinders University College of Science and Engineering.

The elderly, newborns and those with compromised immune systems are especially vulnerable to waterborne infections. The number of individuals with conditions that may put them at risk of ‘opportunistic premise plumbing pathogens’ (OPPP) infection such as advanced age, cancer and immunodeficiency are increasing, warn Flinders’ researchers.

OPPPs, such as Legionella pneumophila, Pseudomonas aeruginosa and Mycobacterium avium, are a group of waterborne pathogens that are slowly receiving increased public health attention in infection control guidelines. “However, drinking water as a source of healthcare associated infections continues to be overlooked or underestimated in this monitoring,” Hayward said.

These waterborne pathogens (or OPPPs) can be disinfectant-resistant and persist in refuges with low nutrients; they form biofilms capable of supporting other clinically relevant pathogens such as Staphylococcus aureus, Enterobacteriaceae, Klebsiella pneumoniae and Escherichia coli.

Once biofilms are formed on taps, showers, drains and other plumbing surfaces, there are numerous potential ways for contamination and transmission, according to the researchers. Outlet device design including splashing and aerosolising of water can also increase the risk of contamination of nearby areas.

 “The rise of these resistant pathogens has been identified by the World Health Organization and US Centers for Disease Control and Prevention as one of the most significant threats to global public health,” said co-author microbiology expert Professor Melissa Brown.

 “While the COVID-19 pandemic has increased the use of disinfectants and sanitisers, particularly in healthcare facilities, these antiseptic soaps do not tackle what’s going on behind the scenes in the water supply pipes and faucets,” Brown said.

Regular changes to tap and outlet filters, hot water service maintenance checks (for heat and pressure) and effective cleaning of shower and tap faucets are recommended for immune-compromised patients receiving health care at home and for post-surgical management.

“These measures can help reduce the risk of waterborne infections in home care, along with quality treatments of mains water to provide safe drinking water,” said lead researcher Claire Hayward, from the Flinders University College of Science and Engineering.

The researchers also recommend broad, universal surveillance guidelines to understand the role of drinking water and water-related devices to reduce healthcare-associated infections and the rise of possible antimicrobial resistance that poses a threat to at risk individuals in healthcare as well as residential settings.

The article ‘Hospital water as the source of healthcare associated infection and antimicrobial resistant organisms’ (2022) by Claire Hayward, Melissa H Brown and Harriet Whiley has been published in the journal Current Opinion in Infectious Diseases.

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