News and Opinions  –  2018

One Health – working together for improved antibiotic use

2018-09-19

One Health is often used as a buzzword – a word that evokes reactions and feels intuitively positive. Unfortunately, it is often poorly defined and understood. One attempt to define it is as a connectivity. The health of humans is connected to the health of animals and plants and vice versa. We all share this space, whether we call it a biome, ecosystem or Mother Earth.

Photo: Noah Busher, Unsplash.

Interconnected health

In 2014, the UK Department of Health developed a series of systems maps in an attempt to detail the factors influencing the development of antimicrobial resistance on different levels. The resulting maps reveal an intricate mesh of connectiveness between humans, animals and the environment. It is therefore impossible to address antibiotic resistance only as an issue for human health, animal health or environmental health. While it is very difficult or even impossible to quantify their respective contributions to the emergence and spread of antibiotic resistance, there are clear examples of situations where this type of cross-talk happens.

Human use and misuse of antibiotics

In human medicine, much of the current use of antibiotics should be called misuse. Poor access to health care, diagnostics and antibiotics all drive this misuse in many low- and middle income countries. Meanwhile, in high income countries where access to services is not a problem, misuse is often driven by just-in-case prescriptions and a laissez-faire attitude among both prescribers and patients towards the potential harm caused to both individuals and societies by driving the selection of resistance.

Two common sources of unnecessary use of antibiotics are in treatment of viral diseases, and unnecessary use of broad-spectrum agents. In many cases, distinguishing between a viral or bacterial origin of a disease may be difficult without laboratory or point-of-care tests which complicates the issue in low- and middle income countries, but even in high income countries antibiotics are prescribed at alarming rates for upper respiratory tract infections such as common colds. Where an adequate species identification is not or cannot be performed, a broad spectrum drug may be used. Broad spectrum antibiotics will target a wider range of potentially disease-causing bacteria, but will also cause more damage to our microbiomes and cause a selective pressure on more species of bacteria.

Use and misuse in animals

When talking about antibiotic use in animals, the companion animal sector is often seen as less important in the big picture of things. However, our pets live very close to us – sometimes even in our beds – so there is great potential for transmission of bacteria between the pet and the owner. Still, the amounts of antibiotics used in food animals by far overreaches the amounts in pets.

Some estimates state that around 80% of global antibiotic use is within food animal production. However, this number doesn’t really say so much – the live biomass of animals is still greater than the human biomass, and comparisons between sectors are in fact futile. What is clear is that the food animal sector uses antibiotics in a non-appropriate manner when the animals are fed antibiotics for growth promotion or as avoidable routine prevention. This type of use must be separated from the legitimate use of antibiotics for treatment of disease, whether it includes treating a whole flock or herd, or just individual animals. And the legitimate use of antibiotics needs to be rational as within human medicine: based on a proper diagnosis by a veterinarian and following the best available evidence and guidelines.

Antibiotics in the environment

Most antibiotics that we humans or our animals consume end up in the environment in one way or the other as they are excreted as active substances in urine or feces. In locations where sewage treatment is lacking, the antibiotic residues leak directly to the environment, and where there is sewage treatment, the treatment procedures are simply not designed to remove pharmaceutical residues. An extreme case is the pharmaceutical manufacturing industry, where production waste may be released into waste water treatment plants that are completely incapable of processing it. But even after human use, residues of pharmaceuticals including antibiotics leak into the environment – studies clearly show that antibiotics, and thereby antibiotic resistance, is found downstream of urban wastewater treatment facilities.

Picking the low-hanging fruits

It seems obvious that there remains a lot to be done to reduce the use and consequent environmental exposure to antibiotics, and it is easy to be discouraged by the vastness of the venture and the obstacles ahead. One way of addressing antibiotic resistance is therefore to start with picking the low-hanging fruits:

  • In human medicine, it would be to weed out the just-in-case use where the cause of disease is generally viral.
  • In animals, it could be ceasing to use antibiotics for growth promotion or routine prophylaxis where other adequate means of disease prevention are available.
  • In the environmental field it could be to implement waste water purification at the point of the largest emissions, such as pharmaceutical manufacturing plants or hospitals.

Such efforts would bring about a dramatic reduction of antibiotic exposure and thus reduce the selective pressures that fuel the emergence and spread of resistance.

End the blame game

Regardless of which perspective one approaches antibiotic resistance from, there is no need for a blame game or pointing fingers in either direction. The one health perspective is an attempt to view all health as interconnected and thus all stakeholders share a responsibility to use antibiotics wisely – use them where they are needed to safeguard health and stop using them where other alternatives are available and appropriate, all in the interest of reducing the exposure and selective pressure exerted by antibiotics.

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