AMR research leads to China banning antibiotic from animal feed
11 Jul 2017
This case study forms part of our Investing for Impact report, looking at how MRC- funded research delivers impact. More can be found in the Investing for Impact section of our website.
In 2015, MRC-funded scientists identified a new form of a gene in China which affords protective resistance to the last-resort antibiotic, colistin. By working closely with the Chinese government, the team was able to instigate an unprecedented policy change in 2016, designed to combat the spread of antibiotic resistance
Antibiotic resistance is genetically transmitted. As such, studying the genes involved in this process can help scientists understand how it arises and more importantly, how it spreads. One of the most disturbing aspects of antibiotic resistance is the discovery that genes for resistance are often contained on a plasmid, a small piece of DNA that is not part of a bacterial chromosome. These plasmids move freely within the bacterial world, hopping from one bacterium to another, and even jumping from one species of bacteria to another. Plasmids encoding antibiotic resistance thus assist the rapid spread of resistance around the globe.
In 2015, Professor Timothy Walsh and his team at the University of Cardiff, along with collaborators in China, identified a gene called mcr-1 that allowed bacteria to survive an antibiotic known as colistin. This ground-breaking discovery shook the infectious disease field, as it meant that certain bacterial infections would be impossible to treat with any of the antibiotics we currently have, a scenario described as the “post-antibiotic future”. Although originally identified in China, mcr-1 has been subsequently reported in more than 30 countries including the UK, spanning four continents.
China is one of the world’s biggest users of colistin in agriculture, primarily in animal feed as a growth-promoter. It is likely that colistin resistance evolved in this context. Since discovering mcr-1, Professor Walsh and his team have worked closely with the Chinese government to examine the use of colistin in agriculture. As a result, in July 2016 the Ministry of Agriculture in China announced that colistin will be banned from animal feed, effective from 1 November 2016. This ground-breaking event will lead to the withdrawal of more than 8000 tonnes of colistin as a growth promoter from the Chinese veterinary sector, which will be replaced by other non-human antibiotics supplemented by traditional Chinese medicines. Europe meanwhile remains an abundant user of colistin for veterinary purposes; it is the fifth most used antimicrobial for food-producing animals in the 26 EU/EEA countries. Therefore the European Medicines Agency (EMA) re-evaluated their advice on using colistin in European veterinary practices and forwarded a position paper in June 2016. This paper recommended that colistin sales for use in animals should be reduced to the minimum feasible.
Professor Walsh is a world renowned expert in the spread of antibiotic resistance in a group of bacteria known as Gram-negative bacteria. In 2010, he was part of a team that reported a newly identified gene (ndm-1) that confers multi-drug resistance, and was linked to travel between Europe and South Asia, especially for medical tourism.
With MRC funding, in 2011 Professor Walsh continued studying antibiotic resistance in Gram-negative bacteria. Infections with Gram-negative bacteria are usually treated with a class of antibiotics known as beta-lactam drugs, of which penicillin is the best known. Since Gram-negative bacteria have become resistant to most other antibiotics, drugs called carbapenems (the most powerful beta-lactams) are now used to treat these infections. Unfortunately, carbapenem-resistant strains of several Gram-negative bacteria have been identified over the past few years, notably ndm-1. For these infections, colistin is used as a ‘last resort’; for example, it is one of the few antibiotics able to treat ndm-1 positive bacterial infections. Now, with the identification of colistin-resistant bacteria, tackling antibiotic resistance has become an even more urgent global priority.
Policies aimed at reducing or eliminating antibiotic misuse must be founded on rigorous underpinning science that investigates the mechanism and spread of antibiotic resistance. Projects such as this exemplify the MRC’s mission of scientific excellence driving improvements in human health, both nationally and internationally. Thanks to the efforts of these scientists, the emergence of colistin-resistance became headline news across the world, eventually leading to an unprecedented policy change to fight antibiotic resistance.
“This is a remarkable example of how scientific discoveries can positively impact on animal and human populations. Our work highlights the value of international collaboration and the importance of working in partnership with policy-makers. Above everything else we need international accountability and a commitment to implement realistic action plans.” - Professor Timothy Walsh
Award details: G1100135