Canada's priority antimicrobial-resistant pathogens

Last updated: 2025-06-02

Learn about Canada's updated list of pathogens that pose a risk to people in Canada due to antimicrobial resistance (AMR).

Why prioritize antimicrobial-resistant pathogens

Antimicrobials are essential for preventing and treating infections caused by bacteria, viruses, and fungi. However, resistance to these treatments is rising, making infections harder to treat, prolonging illness, increasing the risk of complications, and driving up healthcare costs. AMR is a growing public health challenge in Canada and globally.

In 2023, federal, provincial and territorial ministers of health and agriculture released the Pan-Canadian Action Plan on Antimicrobial Resistance to coordinate and accelerate the pan-Canadian response to address AMR. Prioritizing AMR pathogens helps focus resources on:

strengthening surveillance
strengthening antimicrobial stewardship activities
improving infection prevention and control measures
supporting the development of new treatment and diagnostic strategies

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Global and national initiatives

For nearly 2 decades, national and international health agencies have been working to identify and categorize the most pressing AMR threats to inform surveillance, prevention, and response efforts.

In 2015, the Public Health Agency of Canada (PHAC) conducted its first AMR prioritization exercise, which laid the foundation for the Canadian Antimicrobial Resistance Surveillance System (CARSS) and helped shape surveillance priorities.

In 2013, the U.S. Centers for Disease Control and Prevention released its first AMR priority pathogen list, which was updated in 2019. The World Health Organization first published its bacterial priority pathogens list in 2017, with an update in 2024, and released its fungal priority pathogens list in 2022.

Building on enhanced surveillance data from CARSS and other national programs, PHAC has since updated Canada's AMR priority pathogen list.

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Overview of the prioritization process

PHAC conducted a comprehensive prioritization of antimicrobial-resistant pathogens to reflect emerging bacterial, viral, and fungal threats and evolving antimicrobial-resistant dynamics in Canada. We updated Canada's original (2015) priority antimicrobial-resistant pathogen list to reflect the evolving landscape.

We systematically assessed a total of 155 pathogens known to pose a risk to people in Canada. Of these, 68 (44%) exhibited evidence of AMR. Through a rigorous screening process, our subject matter experts identified and assessed 29 antimicrobial-resistant pathogens. We used a multi-criteria decision analysis framework to evaluate the final list of pathogens. This framework integrates both available qualitative and quantitative Canadian data from 2017 to 2022 to guide decision-making.

We scored and ranked antimicrobial-resistant pathogens in tiers based on 9 weighted criteria:

trend
detection
morbidity
incidence
treatability
health equity
preventability
case fatality ratio
mode of transmission

These criteria align with international best practices, and were refined to reflect Canada's specific public health priorities. Notably, Canada is the first country to incorporate health equity as a criterion in an AMR pathogen prioritization exercise. Its inclusion aligns with the Government of Canada's commitment to addressing health disparities and ensures that populations disproportionately affected by AMR are considered in future public health strategies.

List of priority antimicrobial-resistant pathogens

Based on this assessment, a total of 29 antimicrobial-resistant pathogens were categorized by tier, reflecting their relative public health impact.

Tier 1: High priority group

carbapenem-resistant Enterobacterales
drug-resistant Neisseria gonorrhoeae
carbapenem-resistant Pseudomonas aeruginosa
carbapenem-resistant Acinetobacter spp.
Candida auris
extended spectrum β-lactamase-producing Enterobacterales

Tier 2: Medium-high priority group

drug-resistant Shigella spp.
Mycoplasma genitalium
drug-resistant Streptococcus pneumoniae
methicillin-resistant Staphylococcus aureus
vancomycin-resistant Enterococcus spp.
drug-resistant Salmonella spp. (non-typhoidal)

Tier 3: Medium-low priority group

clindamycin-resistant invasive group A Streptococcus
drug-resistant Influenza A
drug-resistant human immunodeficiency virus
drug-resistant group B Streptococcus
Clostridioides difficile
multi-drug resistant Mycobacterium tuberculosis
drug-resistant Aspergillus spp.
drug-resistant Salmonella spp. (typhoidal)

Tier 4: Low priority group

drug-resistant Haemophilus influenzae
drug-resistant Helicobacter pylori
drug-resistant Candida spp., excluding Candida auris
drug-resistant Campylobacter spp.
drug-resistant Bacteroides spp.
Ureaplasma spp.
drug-resistant Treponema pallidum
drug-resistant Chlamydia trachomatis
drug-resistant pulmonary non-tuberculosis Mycobacteria

Highlights

Tier 1 and tier 2 pathogens pose the highest risk to public health, driven by high morbidity, limited treatment options, and rising resistance patterns.
Candida auris and Mycoplasma genitalium were included for the first time due to their diagnostic challenges, high morbidity (C. auris), and increasing resistance (M. genitalium).
Drug-resistant Shigella and M. genitalium are of particular concern due to increasing resistance and their growing role in sexually transmitted infections (STIs) within the gay, bisexual and other men who have sex with men (gbMSM) population.
31% of prioritized pathogens are primarily associated with healthcare settings (nosocomial infections) but can also be transmitted in the community.
45% of prioritized pathogens disproportionately impact vulnerable populations, emphasizing the importance of targeted public health interventions.

Implications for public health

The findings of this prioritization effort demonstrate Canada's commitment to addressing AMR through evidence-based strategies.

Tier 1 and Tier 2 pathogens collectively represent the most critical AMR threats for Canada, requiring focused resources for prevention, early detection, and improved surveillance.
The inclusion of health equity highlights the need for targeted strategies to mitigate AMR's impact on marginalized populations, particularly in STIs.

Focusing on the highest-risk pathogens, Tier 1 and Tier 2, will support the effective use of resources to protect public health and strengthen Canada's response to antimicrobial resistance.

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2025-06-02

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