Research and analysis

UK-VARSS 2022 Highlights

Updated 24 October 2024

Published November 2023
Updated October 2024

1. Antibiotic sales

1.1 Sales for food-producing animals (mg/kg)

Sales of veterinary antibiotics for use in food-producing animals, adjusted for animal population, were 25.7 mg/kg; this is a 9% (2.6 mg/kg) decrease since 2021 and an overall 59% (36.6 mg/kg) decrease since 2014. This represents the lowest sales ever recorded.

Infographic showing the sales in mg/kg between 2014 and 2022:

• 2014: 62.3
• 2015: 56.5
• 2016: 39.0
• 2017: 32.1
• 2018: 29.0
• 2019: 30.4
• 2020: 30.2
• 2021: 28.3
• 2022: 25.7 which is a 9% decreased compared to 2021 and a 59% decrease since 2014.

Sales of Highest Priority Important Antibiotics (HP-CIAs) in food-producing animals remain at very low levels at 0.12 mg/kg in 2022 and account for less than 0.5% of total sales.

Infographic showing the classes of HP-CIAs and total sales for 2014, 2021 and 2022:

• Total HP-CIAs: In 2014 0.67 mg/kg were sold, in 2021 0.12 mg/kg were sold and in 2022 0.12 mg/kg were sold which represents a 82% decrease since 2014.
• Total Fluoroquinolones: In 2014 0.35 mg/kg were sold, in 2021 0.10 mg/kg were sold and in 2022 0.10 mg/kg were sold which represents a 72% decrease since 2014.
• Total 3rd and 4th generation cephalosporins: In 2014 0.19 mg/kg were sold, 0.02 mg/kg were sold and in 2022 0.02 mg/kg were sold which represents a 90% decrease since 2014.
• Colistin: In 2014 0.12 mg/kg was sold, in 2021 0.00 mg/kg was sold and in 2022 0.00 mg/kg was sold which represents a 100% decrease since 2014.

1.2 Sales of antibiotics for all animals in tonnes

In 2022 the total quantity of antibiotic active ingredient sold in the UK was 193 tonnes, the lowest sales to date.

Infographic showing the total sales for all animals in tonnes

• 2014: 447
• 2015: 406
• 2016: 293
• 2017: 246
• 2018: 223
• 2019: 229
• 2020: 227
• 2021: 212
• 2022: 193 which is a reduction of 57% since 2014.

Tetracyclines remain the most sold antibiotic class (32%), followed by penicillins (28%).

1.3 Sales of HP-CIAs for all animals in tonnes

Sales of HP-CIAs for 2022 was 0.91 tonnes representing a small increase of 0.01 tonnes since 2021 but a reduction of 81% (3.9 tonnes) since 2014. Sales of HP-CIAs continue to represent a small proportion (less than 0.5%) of total veterinary antibiotic sales.

2. Antibiotic usage

Antibiotic usage refers to the amount of antibiotics prescribed and/or administered per sector. The data have been collected and provided to the VMD by the animal industry on a voluntary basis. Total coverage of all sectors is at least 90%.

2.1 Antibiotic usage by food-producing animal species

Infographic showing the antibiotic usage, in tonnes, by food-producing animal species for 2022, the change since 2021 and the percentage change since the date of first publication:

• Pigs: 56.4 which is equivalent to 71.8 mg/kg. This is a 15.5 mg/kg decrease since 2021 and represents an overall decrease of 74% since date of first publication in 2015
• Broilers: 13.6 which is equivalent to 14.1 mg/kg. This is a 0.4 mg/kg increase since 2021 and represents an overall decrease of 71% since date of first publication in 2014.
• Gamebirds: 6.7 which is a 2.2 tonnes decrease since 2021 and represents an overall decrease of 66% since date of first publication in 2016.
• Salmon: 3.1 which is equivalent to 18.6 mg/kg. This is a 7.2 mg/kg decrease since 2021 and represents an overall increase of 16% since date of first publication in 2017.
• Turkeys: 2.8 which is equivalent to 35.4 mg/kg. This is a 7.2 mg/kg decrease since 2021 and represents an overall decrease of 84% since date of first publication in 2014.
• Laying hens: 1.61 which is reported at 0.23% bird days. This is a 0.10% bird days decrease since 2021 and represents a 65% decrease since date of first publication in 2016.
• Trout: 0.51 which is equivalent to 44.1 mg/kg. This is a 35.2 mg/kg increase since 2021 and represents an overall increase of 130% since date of first publication in 2014.
• Ducks: 0.05 which is equivalent to 0.3 mg/kg. This is a 1.4 mg/kg decrease since 2021 and represents an overall decrease of 98% since date of first publication in 2014.

2.2 Highest Priority Critically Important Antibiotics by food-producing animal species

Infographic showing the use of HP-CIAs in kg and change since 2021 as well as change since when data was first published:

• Trout: 25.1 which is equivalent to 2.2 mg/kg. This is a 1.1 mg/kg decrease since 2021 and represents an overall decrease of 67% since date of first publication in 2017.
• Gamebirds: 23.2. This is a 3.3 kg decrease since 2021 and represents an overall decrease of 64% since date of first publication in 2016.
• Pigs: 9.53 which is equivalent to 0.01 mg/kg. This is a 0.02 mg/kg decrease since 2021 and represents an overall decrease of 99% since date of first publication in 2015.
• Meat poultry: 1.26 which is equivalent to 0.00001 mg/kg. This is a 0.05 mg/kg decrease since 2021 and represents an overall decrease of 99% since date of first publication in 2014.

3. Antibiotic resistance in zoonotic and commensal bacteria from healthy animals at slaughter

3.1 Key resistance outcome indicators: E. coli

The harmonised monitoring indicators combine results from healthy pigs and poultry at slaughter to give an idea of the major trends in UK AMR surveillance and are internationally comparable. The overall picture for 2022 is positive. The proportion of isolates showing full sensitivity to the panel of antibiotics tested has continued to increase, and the proportion of presumptive extended-spectrum beta-lactamase (ESBL-)/AmpC-producing E. coli has remained stable.

Infographic showing the proportion of E. coli isolate fully sensitive to the panel of antibiotics tested against presumptive ESBL-/AmpC-producing E. coli:

• 2014/2015, the proportion of E. coli isolates fully susceptible was 0.179. Presumptive ESBL-/AmpC-producing E. coli was not tested.
• 2015/2016, the proportion of E. coli isolates fully susceptible was 0.197. Presumptive ESBL-/AmpC-producing E. coli was 0.274.
• 2016/2017, the proportion of E. coli isolates fully susceptible was 0.232. Presumptive ESBL-/AmpC-producing E. coli was 0.251.
• 2017/2018, the proportion of E. coli isolates fully susceptible was 0.337. Presumptive ESBL-/AmpC-producing E. coli was 0.143.
• 2018/2019, the proportion of E. coli isolates fully susceptible was 0.327. Presumptive ESBL-/AmpC-producing E. coli was 0.133.
• 2019/2020, the proportion of E. coli isolates fully susceptible was 0.367. Presumptive ESBL-/AmpC-producing E. coli was 0.101.
• 2020/2021, the proportion of E. coli isolates fully susceptible was 0.387. Presumptive ESBL-/AmpC-producing E. coli was 0.143.
• 2021/2022, the proportion of E. coli isolates fully susceptible was 0.402. Presumptive ESBL-/AmpC-producing E. coli was 0.129.

3.2 Resistance in Salmonella spp.

In 2022, full susceptibility in Salmonella increased in broilers and layers and remained stable in turkeys.

Infographic showing percentage susceptibility in Salmonella in broilers, layers and turkeys:

• In broilers, full susceptibility was 64% in 2014, 67% in 2016, 84% in 2018, 72% in 2020 and 79% in 2022.
• In layers, full susceptibility was 93% in 2014, 85% in 2016, 81% in 2018, 78% in 2020 and 93% in 2022.
• In turkeys, full susceptibility was 31% in 2014, 22% in 2016, 20% in 2018, 22% in 2020 and 20% in 2022.

3.3 Resistance in Campylobacter spp.

In 2022, there were very high levels (between 20% and 50%) of resistance to ciprofloxacin in Campylobacter from broilers and turkeys. This was the first-year resistance in C. coli was tested.

Infographic showing percentage resistance to ciprofloxacin in Campylobacter spp.

• C. jejuni, ciprofloxacin resistance in broilers was 44% in 2014, 41% in 2016, 48% in 2018, 59% in 2020 and 59% in 2022.
• C. jejuni, ciprofloxacin resistance in turkeys was 35% in 2014, 35% in 2016, 31% in 2018, 35% in 2020 and 26% in 2022.
• C. coli, ciprofloxacin resistance in broilers was not tested in 2014, 2016, 2018 and 2020 and was 27% in 2022.
• C. coli, ciprofloxacin resistance in turkeys was not tested in 2014, 2016, 2018 and 2020 and was 45% in 2022.

3.4 New surveillance for 2022

This year’s harmonised monitoring includes three new species of bacteria; Campylobacter coli, Enterococcus faecalis, Enterococcus faecium. The addition of Enterococcus allows for detection of vancomycin resistance enterococci (VRE), which is of clinical importance. No VRE were detected.

3.5 Amplified detection of ESBL-/AmpC-producing E. coli

We also perform a more sensitive type of testing using selective media. This test inhibits the growth of susceptible bacteria but allows ESBL-/AmpC-producing E. coli to multiply, making them easier to detect. This tells us the proportion of individual birds carrying resistance to 3rd and 4th generation cephalosporins even at very low levels.

Infographic showing percentage resistance on ESBL-, AmpC- and ESB/AmpC-producing E. coli in broilers and turkeys:

• In broilers:
  • ESBL resistance was 19% in 2016, 4% in 2018, 3% in 2020 and 8% in 2022.
  • AmpC resistance was 11% in 2016, 6% in 2018, 1% in 2020 and 3% in 2022.
  • ESBL/AmpC resistance was 0.5% in 2016 and 0% in 2018, 2020 and 2022.
• In turkeys:
  • ESBL resistance was 3% in 2016, 2% in 2018, 1% in 2020 and 8% in 2022.
  • AmpC resistance was 1% in 2016, 1% in 2018, 0.3% in 2020 and 0.8% in 2022.
  • ESBL/AmpC resistance was 0% in 2016, 2018, 2020 and 2022.

There was an increase in the prevalence of broilers and turkeys carrying ESBL- and AmpC-producing E. coli compared to 2020. Of these organisms from broilers, 77% were co-resistant to ciprofloxacin, an increase from 37% in 2020.

4. Antibiotic resistance in clinical surveillance

Clinical surveillance aims to provide veterinarians with relevant treatment information using results from bacteria isolated from diagnostic samples. As scanning surveillance is subject to biases and differences in the number of samples, the results are not representative of the UK’s wider animal populations.

4.1 Key findings

• 7,284 isolates were tested for AMR in England and Wales
• E. coli and Salmonella were the most frequently tested bacteria
• Resistance was usually highest to the most commonly used antibiotics; aminopenicillins and tetracyclines
• Resistance tended to be higher in E. coli isolated from young animals, likely reflecting more frequent treatment

4.2 Resistance in Escherichia coli

• Of the 984 E. coli isolates tested from all species, 24% were multi-drug resistant, that is, resistant to four or more individual antibiotics. This was highest in cattle (40%).
• The highest levels of resistance were detected to the most commonly used antibiotics; the aminoglycoside streptomycin (54%), the aminopenicillin ampicillin (49%) and tetracycline (46%).
• In isolates from neonatal sheep, resistance to spectinomycin declined from 45% in 2021 to 23% in 2022. This is possibly due to withdrawal of this antibiotic from the market.
• Highest priority critically important antibiotics (HP-CIAs), resistance was low across all species; cefotaxime (3.7%), cefpodoxime (0.9%), ceftazidime (0.7%) and enrofloxacin (2.5%).

Infographic showing percentage of E. coli isolates with multi-drug resistance, that is, resistant to four or more individual antibiotics:

• In pigs, 22% of isolates were multi-drug resistant in 2022
• In chickens, 22% of isolates were multi-drug resistant in 2022
• In turkeys, 0% of isolates were multi-drug resistant in 2022
• In cattle, 40% of isolates were multi-drug resistant in 2022
• In sheep, 7.3% of isolates were multi-drug resistant in 2022

4.3 Resistance in Salmonella spp. from animals and their environment

• Of the 5,562 Salmonella isolates tested, 24% of isolates from all species showed resistance to at least one antibiotic. This was highest in turkeys (77%) and pigs (72%).
• A change to legislation in 2021 meant that Salmonella isolates from dogs became reportable under the Zoonoses Order in Great Britain. The number of isolates retrieved from dogs has increased from 105 in 2020 to 924 in 2022.
• HP-CIA resistance was generally low (>2%), except to the quinolone nalidixic acid in turkeys (22%). This is difficult to interpret given the disruption to the poultry industry as a result of avian influenza during 2022 which impacted the number of samples submitted.

Infographic showing percentage of Salmonella isolates resistant to at least one antibiotic:

• In pigs, 72% of isolates were resistant to at least one antibiotic in 2022
• In chickens, 17% of isolates were resistant to at least one antibiotic in 2022
• In turkeys, 77% of isolates were resistant to at least one antibiotic in 2022
• In cattle, 13% of isolates were resistant to at least one antibiotic in 2022
• In sheep, 4.6% of isolates were resistant to at least one antibiotic in 2022
• In dogs, 22% of isolates were resistant to at least one antibiotic in 2022

4.4 Private Laboratory Initiative (PLI)

The PLI is a collaborative project between the VMD and APHA, which aims to routinely collect and analyse data from private veterinary laboratories, to provide an additional source of data for AMR surveillance. The PLI is feeding into the new National Biosurveillance Network (NBN) and will run pilot projects from April 2024 to April 2025.

5. Background

5.1 How sales data is collected

In the UK, from 2005 it has been a statutory requirement for pharmaceutical companies to report to the VMD the amount of antibiotic products sold for use in animals. The quantity of active ingredient is calculated from the amounts sold and the product characteristics. These sales data do not take into account wastage of veterinary antibiotics. However, this is the best currently available approximation of the quantity of antibiotics administered to animals in the UK.

5.2 How usage data is collected

Data have been voluntarily provided by producers for the pig, poultry and laying hen sectors, feed companies for gamebirds and veterinary practices for gamebirds and fish.

Usage data collection systems have been put in place to collect data from:

• British Poultry Council for meat poultry
• British Egg Industry Council for the laying hen sector
• Game Farmers Association for gamebirds
• the electronic Medicines Book for pigs
• British Trout Association for trout
• Scottish Salmon Producers’ Association for salmon

Usage data, that is, the amount of antibiotics purchased, prescribed and/or administered, that have the potential to provide much more precise estimates of use. The VMD has been working with the animal production sectors to develop sector-led data collection systems to monitor their antibiotic usage.

5.3 Population Correction Unit (PCU)

Trends in sales of antibiotics between years and different countries cannot be determined without taking into consideration variations in the number and size of animals that may require treatment. Therefore, sales data are analysed using the PCU. This is a standard technical unit of measurement developed by the European Medicines Agency and adopted by EU countries. This allows data to be presented as mg of antibiotic per kg of livestock biomass. For more details refer to, Understanding the mg/PCU calculation used for antibiotic monitoring in food producing animals

5.4 Critically Important Antibiotics (CIAs)

Certain antibiotic classes are categorised by the World Health Organization (WHO) as critically important antibiotics for human use, of which several are designated as ‘highest priority critically important antibiotics’ (HP-CIA). In January 2020, the European Medicines Agency published new scientific advice on the risk to humans from antibiotic resistance caused by the use of highest priority critically important antibiotics (HP-CIAs) in animals.

The report was prepared by Antimicrobial Advice Ad Hoc Expert Group (AMEG). Quinolones, third and fourth generation cephalosporins and polymyxins were classified as category B, where the use of these antibiotics should be restricted, as a result of their critical importance in human medicine. For more details refer to, AMEG 2018 - Categorisation of antibiotics

5.5 How antibiotic resistance is interpreted

Antibiotic resistance in bacteria isolated from animals is monitored through two distinct surveillance programmes; harmonised monitoring and clinical surveillance. The harmonised monitoring scheme is a UK-wide programme in which we test bacteria from the gut of healthy pigs and poultry at slaughter, and the National Control Programme for Salmonella. This give us a representative picture of resistance in key livestock species entering the food chain.

Clinical surveillance involves the testing of bacteria that have been isolated from clinical samples submitted by farmers and private veterinarians to government laboratories in England and Wales. These results are typically published in Chapter 4 of the VARSS report but due to resource constraints, results from this programme will not be published until early 2024. In this report we have published Chapters 1-3, which contains the information for the UK’s key outcome indicator for AMU and AMR Surveillance.

Susceptibility testing for harmonised monitoring is performed using broth microdilution to determine minimum inhibitory concentrations (MICs). Resistance is assessed using EUCAST (European Committee on Antimicrobial Susceptibility Testing) epidemiological cut-off values (ECOFFs). Results interpreted using ECOFFs are reported in full in Supplementary Material 2.

In the 2022 clinical surveillance programme, resistance was assessed by disc diffusion techniques, and interpreted using BSAC (British Society for Antimicrobial Chemotherapy) human clinical breakpoints (CBPs), where available. Broth microdilution testing has continued to develop and apply to an increasing number of organisms over the last two years, with ten bacterial species included this year. Full details of the methods used are available in Supplementary Material 2