The need for a One Health, One Environment approach to tackle antimicrobial resistance
Dr Laura Carter, University of Leeds
The launch of the UK 5-year action plan for antimicrobial resistance (AMR) 2024 to 2029 in May 2024 is a timely reminder that AMR remains one of the top global public health and development threats. Antimicrobials are used to treat many types of infections in humans and animals worldwide. The concern is that due to AMR, antimicrobials will no longer work to treat common infections increasing the risk of disease spread, severe illness. It is estimated that bacterial AMR in humans was directly responsible for 1.27 million deaths in 2019, with projections that by 2050 up to 10 million deaths could be caused by superbugs and associated forms of AMR, matching the annual global death toll of cancer.
Antimicrobial resistance
AMR occurs when microorganisms such as bacteria, viruses, fungi and parasites change over time and no longer respond to medicines making them ineffective. This has far-reaching impacts on both human and environmental health. The development of resistance is a natural process that happens over time through genetic changes in microorganisms, however the misuse and overuse of antimicrobials- including antibiotics, antivirals, antifungals and antiparasitics in humans, animals and plants speeds up this process and is one of the main drivers in the development of drug-resistant organisms.
Agricultural systems, and the use of veterinary medicines such as antibiotics to treat livestock are therefore often implicated in the development of AMR. Animal wastes contain antimicrobial resistant microorganisms and antimicrobial residues which can enter and spread in agricultural systems directly and following manure application to land. The inadvertent release of antimicrobial residues and resistant microorganisms also occurs when wastewater and treated sludges containing human waste are used to meet crop nutrient and irrigation demands. The agricultural environment is therefore an important reservoir of AMR-facilitating constituents including antimicrobials, antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) and research has started to understand the role that exposure in agricultural systems, and the wider environment, plays in the development of AMR in humans. Human exposure can occur for example when AMR-facilitating constituents be are transferred from wastewater irrigated produce to the human gut. This has the potential to increase the prevalence of AMR in exposed populations, although the contribution of ingested wastewater irrigated produce to AMR in humans is currently unclear.
One Environment
Antimicrobials are used to treat common infections in humans and play an important role in sustaining the animal livestock industry. We are faced with the reality that not before long these antimicrobials will become ineffective and infections become difficult or impossible to treat if AMR is not controlled and contained.
It is encouraging to see that the UK National Action Plan (NAP) for Open Government builds on the progress made over the past two decades to understand and mitigate AMR by reducing of antimicrobial use in food producing animals, and the development of improved surveillance and monitoring systems in the environment. New plans across the themes of human health, social care, animal health, and the environment also offer promise in terms of meeting the ambitious goal that AMR will be controlled and contained by 2040.
However, to enable progress to be made in tackling AMR it is important to remember that when we refer to the ‘environment’ that agriculture is recognised as a key component of this. The environment, including agricultural systems are dynamic, with feedback loops connecting compartments such as soil, surface water, ground water, and organisms (e.g. plants, soil invertebrates). The ability for AMR constituents such as antimicrobials and resistant bacteria for example, to transfer between organisms and environmental compartments requires us to and to truly adopt a One Environment approach to AMR, recognising the environment as dynamic, complex and interconnected system.
We recently published a Feature Article in ES&T Water where we explain how crucial it is that we also advocate for joined up thinking that accounts for environmental contamination from a chemical and biological perspective, considering the behaviour of the antimicrobial residues and the resistant organisms together. This underpins the need for a transdisciplinary and cross sector approach to AMR as supported by the University of Leeds initiative AMR@Leeds.
Global challenge
It is important to recognise that AMR is not only a challenge faced by the UK. This is a global threat that affects all countries, in all regions and across all levels of income. The drivers and consequences of AMR are exacerbated by poverty and inequality in low- and middle- income countries. For example, in settings with limited resource and wastewater infrastructure often partially treated or raw wastewater is used as a source of irrigation which can contain higher loads of antimicrobials.
AMR presents a truly global challenge and puts many of the gains of modern medicine at risk. Infections are harder to treat, and development of resistance is now occurring at a rate faster than we can develop new drugs to treat infections. Key to tackling this is targeted efforts to continue to improve our evidence base on AMR, how it spreads in the environment and minimising the spread of AMR, as well as improved understanding of how exposure in the environment links to human health outcomes.
