Antibiotic use in farm animals 'threatens human health'

"Farmers need to dramatically cut the amount of antibiotics used in agriculture, because of the threat to human health, a report says," according to BBC News.

The concern is agricultural antibiotic use is driving up levels of antibiotic resistance, leading to new "superbugs".

The report looked at resistance to antimicrobial drugs, which includes antibiotics as well as antifungal and antiparasitical drugs. Resistance to these drugs is collectively known as antimicrobial resistance (AMR). The report is focused on antibiotic use across the globe. Its results should not be taken as being applicable to the UK as this country has stricter regulations than most other countries.

The report is part of an ongoing review of antimicrobial resistance (AMR) commissioned by the British Prime Minister. This review aims to provide a set of recommendations on how to address AMR globally. 

Who produced the report?

The report (PDF, 737kb) was produced by an independent body chaired by the British economist Jim O'Neill. It looked specifically at antibiotic use in the environment and agriculture.

It focused mainly on the role regulation and financial measures such as taxation and subsidies could play in reducing the risks associated with the agricultural use of antimicrobials and environmental contamination.

The report included a literature review to identify papers describing the use of antibiotics in agriculture. A search was carried out in July 2015 to identify relevant literature, and each relevant study identified was categorised based on whether or not it provided evidence to support a ban on antibiotics in agriculture.

The wider review has published a number of reports covering, for example, the forecast economic impact of AMR, the need for research into new antimicrobial drugs and other steps, and the problem of the overuse of antibiotics.

There are also other reports set to be published on alternatives to conventional antibiotics, the role of sanitation and infection prevention, and control measures in reducing the global burden of drug resistance. 

What does the report say?

The report made a range of observations:

  • The evidence suggests the amount of antimicrobials used in food production internationally is at least the same as that in humans, and in some places is higher. For example, in the US more than 70% of antibiotics that are medically important for humans are used in animals.
  • This form of antimicrobial usage is likely to rise because of the economic growth, increasing wealth and food consumption in the emerging world.
  • When properly used, antibiotics are essential for treating infections in animals, but excessive and inappropriate use of the drugs is a problem.
  • A considerable amount of antibiotics are used in healthy animals to prevent infection or speed up their growth. This is particularly the case in intensive farming, where animals are kept in confined conditions.
  • Some suggest that stopping the use of antibiotics for growth promotion would be significant, particularly in lower-income settings, and would be unjustified without clearer evidence of the extent of the threat to human health.
  • In a literature review of published peer-reviewed research articles carried out as part of the report, only 5% of the 139 academic papers identified argued there was not a link between antibiotic consumption in animals and resistance in humans, while 72% found evidence of a link. The report's authors suggest this supports a link and provides enough justification for policy makers to aim to reduce the global use of antibiotics in food production to a more appropriate level.
  • Some last-resort antibiotics for humans are being used extensively in animals, and there are no replacements currently on the way. This was illustrated by a recent study from China, which identified a gene responsible for colistin resistance in bacteria from livestock, also covered by Behind the Headlines.
  • There is concern over the potential for pollution from antimicrobial manufacture – for example, if untreated waste products containing high levels of end-products or active ingredients are discharged into water courses.    

What are the risks?

The higher use of antimicrobials in animals drives increased drug resistance – just like it does in humans – as the microbes are exposed to the drugs used to treat them more often.

The report raises three main risks associated with the high levels of antimicrobial use in food production:

  • drug-resistant strains could be passed on through direct contact between humans and animals (particularly farmers)
  • drug-resistant strains could be passed to humans more generally when they prepare or eat the meat
  • the drug-resistant strains and the antimicrobials are excreted by the animals and therefore pass into the environment

The report does not specifically mention rare meat, which has been focused on in some of the news coverage.

The news mainly focuses on the possible contamination of this section of the food chain, rather than the wider environmental risks.  

What does the report recommend?

The review made three key recommendations for global action to reduce the risks described:

  • A global target to reduce antibiotic use in food production to an agreed level in livestock and fish, along with restrictions on the use of antibiotics in these animals that are important for humans.
  • The rapid development of minimum standards to reduce antimicrobial manufacturing waste being released into the environment.
  • Improved surveillance to monitor these problems, and progress against global targets.

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