A call for action against antimicrobial resistance in Canadian wastewaters

Carina Thomas, Leland J. Jackson, Sylviane Duval and Joe J. Harrison   |   May 2021 


AMR is current, critical, and cannot be ignored.

Antimicrobial resistance (AMR) is one of the greatest threats to global health in the 21st century. AMR occurs when microorganisms become invulnerable to antimicrobials, such as antibiotics, at doses that should inhibit their growth or kill them. If we cannot contain antimicrobial-resistant organisms—and so far, we are losing that fight—many infections will no longer respond to medicines, making them difficult to treat or even deadly.

Already, in 2018, AMR cost Canadians nearly 5,600 lives from infections that did not respond to first-line antimicrobials; $1.3 billion in healthcare and $2.0 billion in reduced GDP. In only 30 years time, by 2050, antimicrobial-resistant infections are predicted to cost 10 million lives and US$60-100 trillion in economic losses globally every year, if unchecked.

The best way to monitor, treat and prevent AMR is through a One-Health approach.

International working groups have identified that effective wastewater management is essential to reduce the spread of AMR because wastewater—and its purported clean effluent—connects humans, animals, and the environment. However, many ARGs found in pathogens are shared with and originate from bacteria in the environment including those found in natural and engineered freshwater systems. Municipal wastewater contains mobile ARGs that represent every known mechanism of AMR. This makes wastewater treatment plants environmental suppliers of AMR and critical points for AMR control, surveillance and risk assessment.

For example, accumulating evidence suggests that clinically-relevant uropathogenic Escherichia coli (UPEC) exist in treated wastewater effluents, and that they even appear to have adapted to survive wastewater treatment processes. UPEC causes 150 million urinary tract infections (UTIs) globally/year, accounting for 80-90% of community-acquired UTIs. UPEC strains have developed resistance to a growing number of life-saving antibiotics, including trimethoprim-sulfamethozazone (14.6 – 60% resistance in some European countries), fluoroquinolones (55.5 – 85.5% resistance in developing countries) and amoxicillin-clavulanic acid (5.3 – 37.6% resistance in Germany and France).

Return-activated sludge systems, which are key parts of wastewater treatment processes, contain microbiomes that are continuously exposed to pathogens from the sewershed (the area of land where all the sewers flow to a single end point) including our homes and hospitals. The degree to which yesterday’s disinfection protocols provide disinfection today (against resistant bacteria) needs to be continually evaluated. However, we could not identify any country that has regulations for monitoring or removing antimicrobial resistance genes (ARGs) or resistant organisms from wastewater—including Canada. On the contrary, lack of regulation disincentivizes innovations and solutions for AMR in wastewater treatment and surveillance.

Gaps in our knowledge of AMR in wastewater prevent us from developing evidence-based policy recommendations for mitigating it.

Bridging the knowledge gaps of AMR in wastewater (see Box 1) is a strategic research priority for One Health in Canada.




Canada needs to take four key steps against AMR

In Canada, all levels of government share responsibility for managing the collection, treatment and release of wastewater effluent; however, the federal government is responsible for managing the risks posed by substances listed under the Canadian Environmental Protection Act. As well, the federal Wastewater Systems Effluent Regulations are now in force. In spite of this, Canada’s plan to address AMR, Tackling Antimicrobial Resistance and Antimicrobial Use: A Pan-Canadian Framework for Action25 – itself grounded in a One-Health approach – mentions wastewater only once and the environment not at all. As such, Canada has no regulations to control the levels of ARGs released through treated wastewaters – and no screening for AMR is done. We need to take the following actions urgently:


  1. Make policy and regulation for AMR in water stewardship. The Canada Water Act will provide an opportunity for developing nation-wide regulations against AMR in wastewater.

  2. Create a Canadian surveillance network for AMR in wastewater. A surveillance network integrated with the Public Health Agency of Canada will address knowledge gaps and provide much needed data for AMR epidemiology in the environment.

  3. Develop technology for routine monitoring of AMR in wastewater. Field-ready molecular diagnostics will enable detection of antimicrobial resistant organisms and ARGs in wastewater, driving surveillance efforts.

  4. Develop AMR-aware treatment processes to protect water. Reducing the load of ARGs in wastewater and thus, in the One Health cycle, will reduce the burden of infectious disease; protect the lifespan of antibiotics; improve the overall health of surrounding environments, animals and people; and improve the quality and conservation of water.

Box 1. Knowledge gaps of AMR in wastewater.

  • The identities of human, industrial and agricultural sources of AMR genes found in wastewater.

  • The effects of low concentrations of antimicrobials (i.e. lower-than-minimal inhibitory concentrations) of as a selective force in AMR emergence.

  • The identities of environmental organisms that modulate AMR through ecological interactions or act as an AMR gene reservoir.

  • The distance that resistant organisms can travel and how long they persist in water.

  • Epidemiological data linking resistant organisms in water to downstream infections in humans and/or animals.

  • The impact of AMR on the environment and wildlife.

  • The geographic distribution of AMR genes in wastewaters across Canadian cities and our environment.

  • The role of microplastics as foci of AMR development and carriers of AMR elements to agricultural fields used as sludge disposal sites22.

  • Processes of collateral resistance and co-selection (by biocides, disinfectants, toxic metals or advanced oxidation treatment technologies) that can further contribute to AMR, which is particularly relevant due to the increased use of antimicrobials due to COVID-19.


Carina Thomas - University of Calgary, Department of Biological Sciences, University of Calgary, One Health

Leland J. JacksonUniversity of Calgary, Department of Biological Sciences, University of Calgary, One Health, Advancing Canadian Wastewater Assets

Sylviane Duval - OpenTheBox Inc.

Joe J. Harrison -  University of Calgary, Department of Biological Sciences, University of Calgary, One Health

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