How agricultural antibiotic use affects resistance


Prescribing shouldn’t be our only focus when it comes to antibiotic resistance, writes Oscar Klass

During Antibiotic Awareness Week the pharmacy profession will be reminded of the importance of antibiotics—how rational use of antimicrobial agents can lead to decades of effective treatments and delay the development of multi-drug resistant bacteria.

We are imbued with a renewed vigor for writing ‘until all taken’ on our prescription labels and counseling every patient on the importance of completing the prescribed course. Pathology labs are pumping out sensitivity reports and antimicrobial stewardship boards are ensuring nosocomial antibiotic use is optimised.

The discovery of antibiotics, and specifically penicillin, is arguably one of the greatest achievements in modern medicine. It has lead to the development of an array of agents used to cure diseases that were once lethal – a fact that the pharmacy profession has full appreciation of.

But one issue that I believe is overlooked by our profession, and the health-care system as a whole, is the use of antibiotics in animal agriculture and it’s contribution to the development of multi-drug resistant (MDR) bacteria.

Australia has guidelines for appropriate antibiotic use in agriculture; which the respective interest groups ensure their members adhere to. Numerous Australian studies recognise that antibiotic use in agriculture is a contributing factor to the development of MDR bacteria, and recommend ongoing monitoring and stewardship.1

But even if all Australian livestock spend their life in idyllic fields chewing or pecking away at organic feedstock, this is not the reality for a majority of the world’s livestock.

Improved living standards worldwide have resulted in an increased demand for meat – the proliferation of large-scale factory farming is the main mechanism industry uses to meet this demand.

Central to the ethos of factory farming is efficiency, high yields and profitability; these factors are greatly enhanced by continually feeding animals antibiotics. Antibiotics are not used judiciously in this setting, they are used indiscriminately at sub-therapeutic levels to promote growth and prevent infection, with the ultimate goal of maximizing profitability.

While global figures are difficult to report, in 2015 the FDA estimated that in the USA only 30% of ‘medically important’ antibiotics used were for human therapeutic use, comparatively, about 70% were used for animal agriculture. These figures exclude ionophores and other classes of antibiotics not used therapeutically in humans.

The United States is the second largest consumer of antibiotics used in agriculture globally, with China the largest user, and Brazil the third largest.2 With 70% of all antibiotics used in the United States used in agriculture; it is likely that this percentage is even larger in the unregulated environments of China and Brazil.

Lack of regulations has also lead to rampant antibiotic use in developing countries such as India, Thailand, Vietnam and South Africa. It is commonplace in all fields of agriculture, including farming chicken, pigs, cows, salmon and even shrimp farming.3

In our increasing global world, unsuspecting travellers can easily transport dangerous pathogens. Much the same as SARS, ebola or the Zika virus outbreaks, the development of new MDR bacteria affects everyone, even us in Australia.

At first attempt at writing this opinion piece I attempted to dissect this issue systematically – What antibiotics are being used? Who are the worst offenders? Which countries use the most?

But I think that main question is this: Considering that the development of MDR bacteria is potentially the biggest challenge to modern medicine, why is rampant and irrational use of antibiotics allowed in such an unnecessary industry such as animal agriculture?

Eating meat is not essential to human health; increasing global demand is the result of cultural mores and market prices.  It is not possible to feed the world on a diet that primarily composed of meat – it is significantly more effective to feed developing countries elements of a plant based diet. The planet has provided us with a finite amount of recourses – water, soil, feed & arable land – and humankind cannot continue to funnel these precious resources into the animal agriculture machine.

New movements, such as the ‘reducetarian’ movement are acknowledging these limitations. Their goal is to educate individuals on the benefits of consuming less animal products – not only for their health, but also for the health of the planet.

It appears that consuming less animal products, or better yet, avoiding animal products altogether, may be the unsung hero of preserving antibiotic effectiveness for future generations. Individuals can make a difference everyday by choosing where they spend their money; by influencing demand we can make positive change every day.

  1. Responding to the threat of antimicrobial resistance, Australia’s first national antimicrobial resistance strategy 2015-2019. Commonwealth of Australia, 2015.
  2. Center for Disease Dynamics, Economics & Policy. 2015.
    State of the World’s Antibiotics, 2015. CDDEP: Washington, D.C.
  3. Global trends in antimicrobial use in food animal production, Van Boeckel et al, PNAS, vol 112, no 18, p5649-5654


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