Are Drug-Resistant Bugs In The Water?

Rising levels of drug-resistant pathogens pose a serious threat in New Zealand, says University of Auckland Professor of Civil and Environmental Engineering Naresh Singhal.

“I’m concerned by the levels of drug-resistant pathogens in the natural environment, because they’re not properly managed or monitored,” says Singhal, who works within the University’s Centre for Climate, Biodiversity and Society, and is director of its Water Research Centre.

Globally, more than 1.27 million people die of drug-resistant illnesses a year and that’s projected to increase to 10 million deaths per year by 2050. In New Zealand, infections linked to drug resistance cost about $226 million a year and cause about 330 deaths annually, Singhal says.

Health organisations have warned doctors to prescribe antibiotics only when necessary, to reduce the risk of bacteria adapting so that antibiotics no longer wipe them out, he says.

Farmers have also been advised to reduce antibiotic use on livestock, reducing the risk of
antibiotic-resistant pathogens passing from animals into humans.

Viruses, fungi and parasites can also develop resistance to antiviral drugs, antifungals, and antiparasitic medicines, he says.

“Drug resistance – known in scientific terms as antimicrobial resistance – has become a much bigger threat because it’s not just a matter of using less antibiotics on people and farm animals.

“Drug-resistant microbes are spreading through the natural environment,” says Singhal.

People excrete antibiotics and other medicines they have taken, so these drugs enter sewerage systems. Drugs in animal urine and excrement also enter the environment.

“Microbes can develop resistance to antibiotics and other drugs through being exposed to medicines in wastewater treatment plants and waterways.

“When pathogens adapt so they can survive treatment with antibiotics and other medicines, it makes it much harder to treat ordinary infections.

“Diseases can then spread more rapidly and it increases the risk of epidemics,” Singhal says.

In New Zealand, about 20 percent of wastewater systems lack valid consents. Some regularly overflow, pouring raw sewage into the sea and other waterways, he says.

“There’s an urgent need for New Zealand to improve its wastewater treatment systems.

“Our water management organisations need to adopt technologies that prevent high concentrations of antibiotics and other drugs from entering waterways.”

New Zealand needs regulations that set safe limits on drug-resistant microbes in wastewater systems and waterways, Singhal says.

“Poorly managed wastewater systems pose a serious risk of discharging drug-resistant pathogens into lakes, rivers and the sea.”

More monitoring of drug-resistant microbes in wastewater and waterways is also required, he says.

“Mapping hot spots with high levels of antimicrobial resistance would help us predict the risk of drug-resistant pathogens spreading to humans or other animals.

“If people or animals ingest drug-resistant microbes in contaminated water, there’s a much higher risk of them developing a drug-resistant infection.”

Due to climate change, temperatures are rising in wastewater and waterways, creating ideal condition for drug-resistant pathogens to thrive, he says.

“One of the worrying things is a drug-resistant epidemic could sweep through New Zealand and we’re not properly prepared to deal with it.

“There are far too many gaps in our understanding of this threat.”

Singhal and University of Auckland environmental scientist Dr Sam Trowsdale have been granted $20,000 from the University to create a working group of experts from universities, government agencies, Māori environmental organisations, and the wider community to look at ways to tackle drug resistance in New Zealand ecosystems.

Singhal is also applying for funding to study whether suddenly changing the levels of oxygen in wastewater might kill drug-resistant microbes.

Experts interested in joining the working group on antimicrobial resistance can email n.singhal@auckland.ac.nz.

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