Antimicrobial use: Canadian Antimicrobial Resistance Surveillance System (CARSS)

Antimicrobials, especially antibiotics, are a critical component of modern medicine that are regularly used to treat and prevent infections. Antimicrobial resistance (AMR) is a natural phenomenon that occurs when bacteria, viruses, fungi, and parasites evolve over time to resist the effects of antimicrobials used to treat or prevent infections. The misuse and overuse of antibiotics is a well-known factor for accelerating the rates of AMR.

The Canadian Antimicrobial Resistance Surveillance System (CARSS) integrates and synthesizes information from various surveillance systems and laboratory reference services covering humans, animals, and food to present data on AMR and antimicrobial use (AMU) in the human (hospital and community) and animal settings.

Data on antimicrobial sales for use in animals are from the Veterinary Antimicrobial Sales Reporting (VASR) system under Health Canada’s Veterinary Drugs Directorate (HC-VDD) and the Public Health Agency of Canada’s (PHAC) Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS).

Key findings

An overview of findings from antimicrobial use and sales data. Please visit Canadian Antimicrobial Resistance Surveillance System (CARSS): 2024 Key findings for a complete summary.

Human antimicrobial use

Human antimicrobial use continues to decrease, however inappropriate prescribing is common.

Between 2018 and 2023, antimicrobial consumption in the healthcare sector decreased across all Canadian jurisdictions, and the annual number of prescriptions filled by retail pharmacies in the community sector and the total number of prescriptions decreased.

Over the course of the COVID-19 pandemic, there was a consistent decrease in the average monthly prescription rate, with the greatest decrease in 2020 and 2021. However, by 2023, corresponding to the end of the pandemic, there was only a 6.6% decrease in annual antimicrobial prescribing compared to 2019. From 2018 to 2023, nearly one-fifth of prescriptions were deemed inappropriate or suboptimal in participating Canadian healthcare facilities.

Antimicrobials sold for use in animals

Overall, antimicrobials sold for use in animals decreased.

Between 2022 and 2023, after adjusting for biomass or the size of the population, the quantity of medically important antimicrobials sold for use in all animals in Canada decreased (by 3%).

The quantity of sales (mg/kg biomass) increased for:

• beef cattle (by 8%)
• poultry (by 39%)
• and small ruminants (by 20%)

While sales (mg/kg biomass) decreased for:

• dairy cattle (by 12%)
• veal calves (by 43%)
• pigs (by 17%)
• horses (by 10%)
• aquaculture (by 30%)
• cats and dogs (by 6%)

Canada compared to European countries

In 2022, when compared to the 29 European countries reporting to ESAC-Net for total consumption (combining use in healthcare and community sectors), Canada was the tenth lowest consumer of antimicrobials per capita. In the animal sector, in 2022, Canada ranked the fourth highest country in terms of quantities (mg/PCU) of antimicrobials sold for use in production animals (including horses) compared to 31 European countries reporting to ESVAC.

Notes

• For humans, other classes include: bacitracins, 5th generation cephalosporins, cephalosporin beta-lactamase inhibitor combinations, fosfomycin, fusidic acid, glycopeptides, lipopeptides, monobactams, nitrofurans, nitroimidazoles, oxazolidinones, phenicols, carbapenems and polymyxins.
• For animals, other classes include: aminocoumarins, aminocyclitols, amphenicols, β-lactamase inhibitors, cyclic polypeptides, fusidic acid, glycopeptides, nitrofurantoins, nitroimidazoles, orthosomycins, phosphonic acid derivatives, pleuromutilins, polymyxins, pseudomonic acids, streptogramins, carbapenems, and therapeutic agents for tuberculosis.

Source: IQVIA and VASR.

Human consumption and animal antimicrobial sales in Canada

Between 2018 and 2023, noting that there was a minimum of 22 times more animals than people in Canada, the average quantity (in kg) of medically important antimicrobials sold for use in animals was approximately 4 times the amount consumed in humans. After adjusting for biomass, almost the same quantity of antimicrobials was used in humans (90 mg/kg biomass) as were sold for use in animals (86 mg/kg biomass).

In 2023, after adjusting for biomass, the quantity of tetracyclines sold for use in animals was 16 times the amount consumed by humans. Also, there were 14 times more 3rd and 4th generation cephalosporins and 36 times more fluoroquinolones consumed by humans than sold for use in animals. Note that there are no 4th generation cephalosporins approved for use in animals in Canada and no country has approved the use of 5th generation cephalosporins or carbapenems for use in animals.

In 2023, the top three antimicrobial classes consumed in humans were:

• penicillins (75,479 kg)
• first and second generation cephalosporins (37,882 kg)
• sulfonamides (14,688 kg)

In 2023, the top three medically important antimicrobial classes with the highest amounts sold for use in animals were:

• tetracyclines (490,411 kg)
• macrolides (101,093 kg)
• penicillins (95,046 kg)

Setting

• Healthcare
  • Human Antimicrobial Use in the Healthcare Sector
  • National Antimicrobial Prescribing Survey

• Community
  • Human Antimicrobial Use in the Community
  • Human Antimicrobial Use in the Community before and during the COVID-19 pandemic

• Animal
  • Antimicrobials sold for use in animals
  • Farm-level surveillance of AMU and AMR

Comparison of Canadian to European antimicrobial consumption in humans and antimicrobials sold for use in animals in 2022

• In 2022, Canada was the tenth lowest consumer of antimicrobials per capita compared to the 29 European countries reporting to ESAC-Net for the total consumption (combining antimicrobial use in healthcare and community sectors), whereas Canada ranked the fourth highest country in terms of quantities (mg/PCU) of antimicrobials sold for use in production animals (including horses) compared to European countries reporting to the ESVAC network.
• Human AMU data shows that Canada consumed nearly 50.0% more antimicrobials than Netherlands (the country with the lowest consumption) and 59.7% less than the amount consumed by Cyprus (the country with the highest consumption).
• Animal AMU data shows that the quantity sold for use in production animals (mg/PCU) was three times higher than the median of the participating European countries.

Notes

• Caution: Note that the indicators used to measure AMU in humans and antimicrobial sales in animals are different, and caution should be used when making comparisons between the two.
• Human antimicrobial consumption:
  • Data in the figure above shows totals for human consumption, including data combined from healthcare and community sectors if applicable. In Germany, only community sector data were included since healthcare sector data were not reported in the ESAC-Net data by this country.
  • The indicator used for human antimicrobial use is Defined Daily Doses (DDDs) per 1,000 inhabitants per day (ATC group J01).
• Animal antimicrobial sales:
  • Animal data pertain solely to production animals (including horses), excluding dogs and cats.
  • The indicator used for animal antimicrobial sales is milligrams per population correction unit (mg/PCU). The PCU is a measure of animal biomass (the size of the population). For Canada, the metric used is mg/PCU_EU, which uses European animal weights, facilitating a more appropriate comparison of Canadian antimicrobial sales for animals with European sales.

Source: IQVIA, ESAC-Net, ESVAC Network and VASR.