Reducing antibiotics in animals alone ‘will have limited benefits’

Reducing antibiotic consumption in animals alone will often have very limited benefits for human health, according to a new scientific paper published today by the Royal Society.

The paper, which can be viewed here, reiterates the importance of addressing antimicrobial resistance (AMR) in both humans and animals simultaneously.

The National Pig Association (NPA) and the Responsible Use of Animal Medicine (RUMA) alliance have welcomed the research, which they said provided useful context in the ongoing AMR debate but also reinforced the current ‘One Health’ approach being adopted to address the problem in animal and human medicine.

The paper, by B.A.D van Bunnik and Mark Woolhouse from the University of Edinburgh, describes antibiotic resistance as a public health crisis and notes that it is often suggested that resistance arising in food animals contributes to resistance levels in humans.

This study uses a mathematical model to gauge whether the ‘widely suggested intervention of drastically decreasing antibiotic consumption by food animals would be effective’.

It concludes that, as a stand-alone measure, reducing antibiotic consumption by food animals ‘will often have very limited benefits for human health’.

The paper states: “Although it is widely regarded as intuitively obvious that reducing antibiotic consumption in animals would decrease levels of antibiotic resistance in humans this is, in fact, not the case for a wide range of scenarios, especially if this intervention is made in isolation.”

The paper does not, however, suggest that tackling the problem in livestock medicine is not important, concluding that: “A better strategy is an integrated approach that tackles resistance in humans and food animals at the same time.”

It suggests reducing the rate of transmission of resistance from animals to humans ‘may often be more effective’, while the rate of transmission from humans to animals is also important.

“It is thus not enough to only lower the consumption of antibiotics in food animals, the transmission both from and to food animals should also be limited in order to maximise the impact of this and other interventions,” the paper says.

Valuable clarification

NPA senior policy advisor Georgina Crayford said: “This paper reiterates the value of the approach we are taking in the livestock sector to reduce and refine antibiotic use. We are utterly committed to driving ahead with this.

“However, the research also provides valuable clarification in addressing the entirely unwarranted suggestion often made by campaigners that AMR is somehow primarily a problem caused by intensive farming. It isn’t, and the solution lies, as it always has, in taking a robust approach in human and animal medicine.”

RUMA chairman Gwyn Jones said: “The study highlights the complexity of antibiotic resistance and the need for a ‘One Health’ approach to the problem across humans and animals.

“So while it suggests that removal of antibiotics from animal production systems is not the answer to antimicrobial resistance in humans, the food and farming sector should not in any way dilute its current focus on reducing, refining and replacing antibiotic use across all sectors.

“An important point it does raise, however, is that a drive for ‘antibiotic-free’ farm produce is not necessarily beneficial for human health and makes any related detrimental impacts on animal health and welfare even more unjustifiable.

“RUMA therefore retains its position that responsible use of antibiotics alongside well-managed, scientifically-robust reductions is the most appropriate approach.”

MORE REACTION

“The paper does refute the claim by some that removal of antibiotics from animal production systems is the answer to antimicrobial resistance in humans. It also raises the point that the drive for ‘antibiotic free’ is not necessarily beneficial for human health and makes any detrimental impacts on animal health and welfare arising from a drive towards ‘antibiotic free’ unjustifiable.

“Therefore the RUMA approach of responsible use, which is ‘as little as possible, as much as necessary’ is the more considered and appropriate route when implementing antibiotic reduction programmes.”

Daniel Parker, a lecturer at the University of Cambridge Veterinary School and member of RUMA’s independent advisory Scientific Group

“This well-constructed study uses a simple mathematical model to look at what would happen to human health in the event that animals used in food production were given fewer antibiotics. Their model suggests that this action alone would have little effect on levels of antibiotic resistance in humans.

“This finding is consistent with prior reports from the World Health Organization, stating ‘Antimicrobial resistance is a complex problem that affects all of society and is driven by many interconnected factors. Single, isolated interventions have limited impact’.”

Dr Peter Barlow, British Society for Immunology spokesperson, and Reader in Immunology & Infection, Edinburgh Napier University

“Relatively simple models can provide good insight into complex real world situations. Despite the fact that this study ignores the important issue of the environment as a source of resistance, it absolutely reinforces the need for a One Health approach.

“It confirms that a focus on transmission in both directions is important but most importantly reaffirms that if we are to find a solution to this issue it will not be found by addressing antibiotic use in one sector alone.”

Prof Stuart Reid, Principal, Royal Veterinary College

“This paper is to be welcomed and questions the unproven assumption that reducing the use of antimicrobial drugs in farm animal medicine will lead inexorably to lower levels of resistance in human pathogens and therefore that such reduction in veterinary use must be a good thing.

“The assumption seems to have been made that it is contact between animals and man in various forms which is the main driver. This fails to take account of the spread into the environment of resistance factors following drug use in animals and potential subsequent transfer to human commensals and then pathogens – this potentially might be of major significance.”

Prof Peter Lees, Emeritus Professor of Veterinary Pharmacology, Royal Veterinary College

“This is not a mandate for ignoring using antibiotics in animals, rather the study illustrates that an integrated ‘One Health’ approach across all species, including good basic hygiene, is needed to stem the tide of antibiotic resistance.

“It remains the case that increasing the use of any medicine that selects for resistant microorganisms and parasites, such as by more extensive routine use of antibiotics and wormers as part of agricultural intensification, or widespread trivial use of antibiotics in people, will inevitably lead to more medicines resistance.”

Prof Tim Morris, School of Veterinary Medicine and Science, University of Nottingham

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About The Author

Editor of Pig World and contributor to LBM’s other farming publications. Also National Pig Association webmaster. Formerly political editor at Farmers Guardian for many years. Enjoy a bit of media punditry. Brought up on a Leicestershire farm. Work from a shed in the garden in Oxfordshire. Under-9 football coach and big fan of Leicester City and Leicester Tigers. Occasional cricketer.