Research and analysis

UK-VARSS 2020 Highlights

Published 9 November 2021

1. Antibiotic sales

1.1 Sales for food-producing animals in mg/kg

Sales of veterinary antibiotics for use in food-producing animals, adjusted for animal population, were 30.1 mg/kg; a 0.3 mg/kg (1%) decrease since 2019 and a 32.2 mg/kg (52%) decrease since 2014.

Bar chart depicting the sales in mg/kg for food-producing animals from 2014 to 2020:

• In 2014, the total mg/kg was 62.3 mg/kg
• In 2015, the total mg/kg was 56.5 mg/kg
• In 2016, the total mg/kg was 39.0 mg/kg
• In 2017, the total mg/kg was 32.1 mg/kg
• In 2018, the total mg/kg was 29.0 mg/kg
• In 2019, the total mg/kg was 30.5 mg/kg
• In 2020, the total mg/kg was 30.1 mg/kg

Sales of Highest Priority Critically Important Antibiotics (HP-CIAs) in food-producing animals account for 0.5% of total sales and have dropped by 0.03 mg/kg since 2019 and 0.5 mg/kg (79%) since 2014.

Line graph depicting the sales of HP-CIAs in food-producing animals from 2014 to 2020:

2014:

• Fluoroquinolones accounted for 0.35 mg/kg
• Third and fourth generation cephalosporins accounted for 0.19 mg/kg
• Colistin accounted for 0.1 mg/kg

2015:

• Fluoroquinolones accounted for 0.35 mg/kg
• Third and fourth generation cephalosporins accounted for 0.17 mg/kg
• Colistin accounted for 0.1 mg/kg

2016:

• Fluoroquinolones accounted for 0.22 mg/kg
• Third and fourth generation cephalosporins accounted for 0.14 mg/kg
• Colistin accounted for 0.02 mg/kg

2017:

• Fluoroquinolones accounted for 0.16 mg/kg
• Third and fourth generation cephalosporins accounted for 0.11 mg/kg
• Colistin accounted for 0.001 mg/kg

2018:

• Fluoroquinolones accounted for 0.15 mg/kg
• Third and fourth generation cephalosporins accounted for 0.06 mg/kg
• Colistin accounted for 0.003 mg/kg

2019:

• Fluoroquinolones accounted for 0.13 mg/kg
• Third and fourth generation cephalosporins accounted for 0.03 mg/kg
• Colistin accounted for 0.0014 mg/kg

2020:

• Fluoroquinolones accounted for 0.1 mg/kg
• Third and fourth generation cephalosporins accounted for 0.04 mg/kg
• Colistin accounted for 0.00007 mg/kg

In 2020 the total quantity of antibiotic active ingredient sold in the UK was 226.0 tonnes.

Infographic depicting the total sales in tonnes for all animals:

• In 2014, 447 tonnes were sold
• In 2015, 406 tonnes were sold
• In 2016, 293 tonnes were sold
• In 2017, 246 tonnes were sold
• In 2018, 223 tonnes were sold
• In 2019, 229 tonnes were sold
• In 2020, 226 tonnes were sold, which is a decrease of 49% compared to 2014, and of 1% since 2019

Sales of HP-CIAs reduced by 0.18 tonnes between 2019 and 2020 (from an already low level) and have now fallen by 3.7 tonnes (77%) since 2014. Tetracyclines remain the most sold antibiotic class (32% of total sales), followed by beta-lactams (29% of total sales). Sales of HP-CIAs in all animal species represent a small proportion (0.48%) of the overall antibiotic sales.

Infographic depicting the tonnes sold in 2020 for each antibiotic class, and the difference in tonnes sold since 2014:

• In 2020, 73 tonnes of tetracyclines were sold in all animal species. Sales of tetracyclines have decreased by 0.01 tonnes since 2019 and decreased by 108 tonnes since 2014
• In 2020, 66 tonnes of beta-lactams were sold in all animal species. Sales of beta-lactams have increased by 3.1 tonnes since 2019 and decreased by 27 tonnes since 2014
• In 2020, 25 tonnes of trimethoprim/sulphonamides were sold in all animal species. Sales of trimethoprim/sulphonamides have decreased by 0.4 tonnes since 2019 and decreased by 46 tonnes since 2014.
• In 2020, 21 tonnes of macrolides were sold in all animal species. Sales of macrolides have increased by 4.2 tonnes since 2019 and decreased by 29 tonnes since 2014
• In 2020, 21 tonnes of aminoglycosides were sold in all animal species. Sales of aminoglycosides have decreased by 2.6 tonnes since 2019 and decreased by 3.6 tonnes since 2014
• In 2020, 19 tonnes of antibiotics classed as “other” were sold in all animal species. Sales of these antibiotics have decreased by 6.6 tonnes since 2019 and decreased by 4.5 tonnes since 2014
• In 2020, 0.81 tonnes of fluoroquinolones were sold in all animal species. Sales of fluoroquinolones have decreased by 0.23 tonnes since 2019 and decreased by 1.8 tonnes since 2014
• In 2020, 0.27 tonnes of third and fourth generation cephalosporins were sold in all animal species. Sales of third and fourth generation cephalosporins have increased by 0.04 tonnes since 2019 and decreased by 1.1 tonnes since 2014
• In 2020, 0.5 kg of colistin were sold in all animal species. Sales of colistin have decreased by 0.7 kg since 2019 and decreased by 0.8 kg since 2014

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.

2.1 Antibiotic usage by food producing animal species

Infographic depicting the antibiotic usage by food-producing animal species.

Please note that the total coverage represents the percentage of animals covered by the data, except gamebirds which represents an estimate of the total percentage of antibiotic sales.

The total tonnage relates to the weight of antibiotic active ingredient using ESVAC methodology. The total per unit, referred to as the mg/kg for 2020, relates to the amount of active ingredient standardised by kg biomass and calculated using ESVAC methodology.

Percentage doses refers to actual daily bird doses divided by 100 bird days at risk.

Finally, regarding the difference since 2019 and since 2016 for gamebirds, please note that industry estimates suggest that due to Covid restrictions, gamebird rearing reduced by 30% during 2020.

• Pig production data covers >95% of pigs slaughtered in 2020. Total antibiotic usage in pigs was 83.1 tonnes for 2020. Total usage reduced by 5.5 mg/kg between 2019 and 2020 to 105 mg/kg, and usage has now reduced by 172.7 mg/kg (62%) since 2015.
• Meat poultry data covers 90% of the population. Total antibiotic usage in meat poultry was 21.0 tonnes for 2020. In turkeys, total usage reduced by 16.3 mg/kg between 2019 and 2020 to 25.7 mg/kg, and usage has now reduced by 194 mg/kg (88%) since 2014. In broilers, total usage reduced by 1.2 mg/kg between 2019 and 2020 to 16.3 mg/kg, and usage has now reduced by 32.5 mg/kg (67%) since 2014. In ducks, total usage has increased by 0.9 mg/kg between 2019 and 2020 to 2.6 mg/kg, and usage has now reduced by 12.5 mg/kg (83%) since 2014.
• Laying hen data covers 90% of the population. Total antibiotic usage in laying hens was 3.1 tonnes for 2020. In laying hens, total usage reduced by 0.21 % bird days between 2019 and 2020 to 0.47 % bird days, and usage has now reduced by 0.19 % bird days (29%) since 2016.
• Gamebird data covers 91% of the population. Total antibiotic usage in gamebirds was 6.0 tonnes for 2020. In gamebirds, total usage reduced by 4.4 tonnes between 2019 and 2020 to 6.0 tonnes, and usage has now reduced by 14.2 tonnes (71%) since 2016.
• Salmon data covers 100% of the population. Total antibiotic usage in salmon was 5.6 tonnes for 2020. In gamebirds, total usage increased by 15.8 mg/kg between 2019 and 2020 to 29.3 mg/kg, and usage has now increased by 13.2 mg/kg (82%) since 2017.
• Trout data covers 90% of the population. Total antibiotic usage in trout was 0.16 tonnes for 2020. In gamebirds, total usage increased by 4.2 mg/kg between 2019 and 2020 to 13.9 mg/kg, and usage has now reduced by 5.4 mg/kg (28%) since 2017.

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

• Pig production data covers >95% of pigs slaughtered in 2020. Total HP-CIA antibiotic usage in pigs was 41 kg for 2020. Total usage reduced by 0.01 mg/kg between 2019 and 2020 to 0.05 mg/kg, and usage has now reduced by 0.93 mg/kg (95%) since 2015.
• Meat poultry data covers 90% of the population. Total HP-CIA antibiotic usage in meat poultry was 12 kg for 2020. Total usage reduced by 0.001 mg/kg between 2019 and 2020 to 0.008 mg/kg, and usage has now reduced by 1.2 mg/kg (99%) since 2014.
• Gamebird data covers 91% of the population. Total HP-CIA antibiotic usage in meat poultry was 22 kg for 2020. Total usage reduced by 36.2 kg between 2019 and 2020 to 22 kg, and usage has now reduced by 42.5 kg (66%) since 2016.
• Trout data covers 90% of the population. Total HP-CIA antibiotic usage in trout was 48 kg for 2020. Total usage increased by 1.8 mg/kg between 2019 and 2020 to 4.3 mg/kg, and usage has now reduced by 2.3 mg/kg (35%) since 2017.
• Salmon data covers 100% of the population. Total HP-CIA antibiotic usage in salmon was 2.5 kg for 2020. Total usage reduced by 0.01 mg/kg between 2019 and 2020 to 0.01 mg/kg, and usage has now reduced by 0.11 mg/kg (89%) since 2017.

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

3.1 Resistance in Escherichia coli from broilers and turkeys

Overall, the UK can report trends of decreasing AMR in E. coli from healthy broilers at slaughter since 2014.

Resistance to HP-CIAs remains undetected or at low or very low levels in both broilers and turkeys. There has also been a decrease in ESBL/AmpC-producing E. coli detected in broilers and turkeys since 2016, with less than 5% of caecal samples testing positive at slaughter in 2020.

3.2 Resistance in Salmonella spp. from broilers, laying hens and turkeys

In Salmonella collected from broilers and layers as part of the National Control Programmes (NCPs), susceptibility to the full panel of antibiotics tested has decreased since 2018; however, in broilers, it is still higher than in 2014.

All Salmonella isolated from poultry through the NCPs were fully susceptible to the HP-CIAs tested, with the exception of nine isolates from layer flocks, which belong to a serovar that is naturally resistant to colistin.

3.3 Resistance in Campylobacter jejuni from broilers and turkeys

This year, C. jejuni isolates from broilers showed increasing and very high resistance to ciprofloxacin. This situation is not unique to the UK and is occurring despite very low fluoroquinolone use in meat poultry. In turkeys, resistance levels are more stable, but remain high. Resistance to erythromycin, a first-line treatment for Campylobacter infection in people, remained very low in broilers and turkeys (<1%).

Please note that regarding the description of percentage resistance referenced: rare is <0.1%, very low is 0.1% to 1%, low is >1% to 10%, moderate is >10% to 20%, high is >20% to 50%, very high is >50% to 70% and extremely high is >70%.

Line graph depicting the percentage of E. coli isolates resistant to ciprofloxacin, cefotaxime and ceftazidime between 2014 and 2020 in broilers:

Ciprofloxacin:

• In 2014, resistance to ciprofloxacin was 3.8%
• In 2016, resistance to ciprofloxacin was 1.6%
• In 2018, resistance to ciprofloxacin was 1.1%
• In 2020, resistance to ciprofloxacin was 2.4%

Cefotaxime:

• In 2014, resistance to cefotaxime was 0%
• In 2016, resistance to cefotaxime was 0%
• In 2018, resistance to cefotaxime was 1.6%
• In 2020, resistance to cefotaxime was 0.4%

Ceftazidime:

• In 2014, resistance to ceftazidime was 0%
• In 2016, resistance to ceftazidime was 0%
• In 2018, resistance to ceftazidime was 0.5%
• In 2020, resistance to ceftazidime was 0.4%

Line graph depicting the percentage of E. coli isolates resistant to ciprofloxacin, cefotaxime and ceftazidime between 2014 and 2020 in turkeys:

Ciprofloxacin:

• In 2014, resistance to ciprofloxacin was 7.1%
• In 2016, resistance to ciprofloxacin was 4.9%
• In 2018, resistance to ciprofloxacin was 2.3%
• In 2020, resistance to ciprofloxacin was 2.5%

Cefotaxime:

• In 2014, resistance to cefotaxime was 0%
• In 2016, resistance to cefotaxime was 0.4%
• In 2018, resistance to cefotaxime was 0%
• In 2020, resistance to cefotaxime was 1.0%

Ceftazidime:

• In 2014, resistance to ceftazidime was 0%
• In 2016, resistance to ceftazidime was 0.4%
• In 2018, resistance to ceftazidime was 0%
• In 2020, resistance to ceftazidime was 0.5%

Line graph depicting the percentage of C. jejuni isolates resistant to ciprofloxacin between 2014 and 2020 in broilers:

• In 2014, resistance to ciprofloxacin was 44%
• In 2016, resistance to ciprofloxacin was 41%
• In 2018, resistance to ciprofloxacin was 48%
• In 2020, resistance to ciprofloxacin was 59%

Line graph depicting the percentage of C. jejuni isolates resistant to ciprofloxacin between 2014 and 2020 in turkeys:

• In 2014, resistance to ciprofloxacin was 35%
• In 2016, resistance to ciprofloxacin was 35%
• In 2018, resistance to ciprofloxacin was 31%
• In 2020, resistance to ciprofloxacin was 37%

4. Antibiotic resistance – clinical surveillance

4.1 Resistance in Salmonella spp.

Of the 4,205 Salmonella isolates tested, 68% were susceptible to all of the antibiotics tested. No resistance to third/fourth generation cephalosporins and fluoroquinolones was detected in cattle, pigs, sheep and turkeys.

In chickens, resistance to third/fourth generation cephalosporins (0.1%) and fluoroquinolones (0.3%) was very low. Resistance to ciprofloxacin was detected in a small number of isolates which were detected from chickens, feed and related samples, a pheasant and other non-avian species.

Two isolates detected in an equine environment were multi-drug resistant.

Infographic depicting the percentage resistance of Salmonella isolates to third generation cephalosporins and fluoroquinolones in food-producing animal species in 2020:

Third generation cephalosporin resistance (cefotaxime/ceftazidime):

• 0% of Salmonella isolates from pigs were resistant to cefotaxime/ceftazidime
• 0% of Salmonella isolates from turkeys were resistant to cefotaxime/ceftazidime
• 0.1% of Salmonella isolates from broilers were resistant to both cefotaxime and ceftazidime
• 0% of Salmonella isolates from cattle were resistant to cefotaxime/ceftazidime
• 0% of Salmonella isolates from sheep were resistant to cefotaxime/ceftazidime

Fluoroquinolones:

• 0% of Salmonella isolates from pigs were resistant to fluoroquinolones
• 0% of Salmonella isolates from turkeys were resistant to fluoroquinolones
• 0.3% Salmonella isolates from of broilers were resistant to fluoroquinolones
• 0% of Salmonella isolates from cattle were resistant to fluoroquinolones
• 0% of Salmonella isolates from sheep were resistant to fluoroquinolones

Infographic depicting the percentage of Salmonella isolates fully susceptible to all antibiotics tested in food-producing animal species between 2018 and 2020:

2018

• For pigs (n=202), 14% of Salmonella isolates were fully susceptible
• For turkeys (n=182), 21% of Salmonella isolates were fully susceptible
• For broilers (n=1640), 84% of Salmonella isolates were fully susceptible
• For cattle (n=489), 83% of Salmonella isolates were fully susceptible
• For sheep (n=276), 91% of Salmonella isolates were fully susceptible

2019

• For pigs (n=206), 21% of Salmonella isolates were fully susceptible
• For turkeys (n=270), 19% of Salmonella isolates were fully susceptible
• For broilers (n=1708), 77% of Salmonella isolates were fully susceptible
• For cattle (n=464), 89% of Salmonella isolates were fully susceptible
• For sheep (n=82), 99% of Salmonella isolates were fully susceptible

2020

• For pigs (n=242), 17% of Salmonella isolates were fully susceptible
• For turkeys (n=141), 29% of Salmonella isolates were fully susceptible
• For broilers (n=1659), 74% of Salmonella isolates were fully susceptible
• For cattle (n=404), 72% of Salmonella isolates were fully susceptible
• For sheep (n=69), 94% of Salmonella isolates were fully susceptible

4.2 Resistance in Escherichia coli

Resistance to fluoroquinolones and third generation cephalosporins remains low (≤10%) compared to 2018 for all animal species, the exception being for chickens where in 2019, fluoroquinolone resistance was 11%.

Infographic depicting the percentage of resistant E. coli isolates from broilers and pigs to third generation cephalosporins and fluoroquinolones between 2018 and 2020:

Third generation cephalosporin resistance:

• In 2018, 4.2% of broilers (n=72) and 2.9% of pigs (n=244) were resistant to third generation cephalosporins
• In 2019, 5.9% of broilers (n=102) and 0.9% of pigs (n=440) were resistant to third generation cephalosporins
• In 2020, 1.1% of broilers (n=93) and 2.6% of pigs (n=465) were resistant to third generation cephalosporins

Fluoroquinolone resistance:

• In 2018, 2.8% of broilers (n=72) and 3.3% of pigs (n=244) were resistant to third generation cephalosporins
• In 2019, 11% of broilers (n=102) and 5.9% of pigs (n=441) were resistant to third generation cephalosporins
• In 2020, 5.4% of broilers (n=93) and 2.2% of pigs (n=465) were resistant to third generation cephalosporins

4.3 MIC testing of veterinary pathogens

This year’s clinical surveillance programme has been enhanced to include MIC testing for a core range of key veterinary bacterial pathogens against commonly used clinical antibiotics. This improves the usefulness of our AMR surveillance and will also help vets make better prescribing choices.

Many isolates were susceptible to the panel of antimicrobials tested and when resistance was detected, alternative therapeutic options were likely to be available amongst antimicrobials authorised for veterinary use. Resistance was uncommon or not detected amongst antimicrobials which are often used as second or third line treatment options.

5. Background

5.1 How are sales data 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 are usage data collected?

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

Usage data collection systems have been put in place to collect data from the British Poultry Council (meat poultry), the British Egg Industry Council (laying hen sector), the Game Farmers Association (gamebirds), the electronic Medicines Book (pigs), British Trout Association (trout) and Scottish Salmon Producers’ Association (salmon).

Usage data, that is to say the amount of antibiotics purchased, prescribed and/or administered, 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 What is the 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 population correction unit (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 see the guidance on GOV.UK

5.4 What are 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). Fluoroquinolones, 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 see the European Medicines Agency Categorisation of antibiotics in the European Union.

5.5 How is antibiotic resistance 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, giving 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.

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) human clinical break points (CBPs) and EUCAST epidemiological cut-off values (ECOFFs). Susceptibility results included in the Highlights as well as in the main body of the report were interpreted using CBPs, or ECOFFs where CBPs were unavailable. Results interpreted using both human CBPs and ECOFFs are reported in full in S3.3 of the supplementary material.

In the 2020 clinical surveillance programme, MIC testing was performed for important respiratory pathogens of cattle, sheep, and pigs, and the results were interpreted using veterinary CBPs when possible. Otherwise, resistance was assessed by disc diffusion techniques, and interpreted using BSAC (British Society for Antimicrobial Chemotherapy) human CBPs, where available.

Full details of the methods used are available in S4.1 of the supplementary material.