20th May 2026
New research suggests that food processing or other post-farm production practices are more important to microbial diversity and abundance of AMR genes in retail food.
Levels of antimicrobial-resistant microorganisms found in UK retail meat and leafy greens are unaffected by the farming system – whether it was farmed organically, free-range or conventionally – according to new research.
The metagenome survey, conducted by the Quadram Institute, revealed that food processing, post-farm production, is likely a bigger driver of microbial contaminants on food than differences in farming practice.
To combat the rise of AMR, UK and EU farmers have not been able to use antibiotics routinely to promote the growth of livestock since 2006. Since then, antibiotic use in UK farming has dropped overall, with a 57% decrease in the sales of antibiotics for use in animals between 2014 and 2024 reported by the UK Veterinary Medicines Directorate.
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Microbial communities likely picked up during food processing
The research team sampled over 220 pork, beef, lamb, chicken, salmon, and leafy greens from retailers in the UK between 2018 and 2024, collecting microbial DNA from them in the process.
This DNA was then sequenced to produce a metagenome, which is the total collection of genetic material from a community of organisms.
They found overall that the production method was not a significant driver of microbial diversity or antimicrobial-resistant genes on food at the point of retail.
The microbial communities were predominantly made up of food spoilage bacteria, such as Pseudomonas and Lactococcus, likely to have been picked up or increased during processing rather than on the farm.
Sam Mellor from the Quadram Institute said: “Our findings support the suggestion that food processing, post-farm production, shapes the composition of the microbiome on retail food, while the influence of on-farm practices is limited.”
Mr Mellor was keen to stress that the majority of products tested were farmed in the UK, leaving “unanswered questions about the levels of antimicrobial resistance on imported food.”
He added: “Animal husbandry and antimicrobial use in agriculture, as well as organic and free-range farming regulations, can vary substantially between different countries, so similar investigations comparing food production abroad may yield different results.”
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