What is antimicrobial resistance and why does AMR matter?
Antimicrobial resistance (AMR) arises when bacteria (or viruses, fungi and parasites) no longer respond to the drugs designed to prevent the spread of an infection. Antibiotics, for example, are central to much of modern medicine, like helping to protect patients against infection after operations. But some treatments are becoming less effective because the organisms that cause infections are rapidly evolving to be resistant. While that evolution is a natural process, our behaviour – largely through the over-use of antimicrobials for humans, animals and plants - is accelerating resistance.
AMR leads to drug resistant infections, which are harder, and in some cases impossible, to treat. And developing new treatments is also hard: it is more than 50 years since a new class of antibiotic effective against Gram-negative bacteria was discovered and brought to market. Research published in The Lancet indicates that between 1990 and 2021, AMR has killed 36 million people. And with drug resistance infections on the rise, AMR is expected to claim more than 39 million lives between now and 2050, with low and middle-income countries facing a disproportionate burden.
What is causing AMR to increase?
One of the biggest issues for AMR is the over-use of antimicrobial treatments because every usage effectively gives the organisms another chance to acquire resistance. And while we are most familiar with their use in human medicine, antimicrobials are also used widely in agriculture with animals and to a lesser extent with crops. For example, according to the Food and Agriculture Organization of the United Nations, estimates of antibiotic consumption in global agriculture vary from around 63,000t/ year to over 240,000t/year. However, 75-90% of those antibiotics are excreted from animals un-metabolized and enter sewage systems and water sources. According to a 2023 UN Environment Programme report, AMR is also linked to the pollution and waste driven by human activity, especially unsustainable consumption and production patterns.
The main sources of biological and chemical pollutants in the environment that contribute to AMR are poor sanitation, sewage and waste effluent which could come from communities, pharmaceutical manufacturing, healthcare facilities or use of use of antimicrobials and manure in intensive crop production. These may contain resistant micro-organisms, as well as antimicrobials, pharmaceuticals, microplastics, metals and other chemicals, which all increase the risk of AMR in the environment. Other contributing factors to transmission and spread of AMR in the environment include wildlife, international movements of people and goods, companion animals, airborne transmission, rapid urbanisation and climate change.
The use of antibiotics on farms has been described by the World Health Organization as ‘one of the biggest threats to global health, food security and development today’, due to their contribution to antimicrobial resistance.
The cost of AMR is rising
According to research from the Global Leaders Group on AMR, AMR is already a leading cause of death globally, directly responsible for 1.27m deaths annually, one in five of which occur in children under the age of five, mainly in low- and middle-income countries. Beyond this, AMR will have a ‘catastrophic impact on the global economy, including huge increases in health expenditure and lost productivity,’ the group warns. ‘AMR is expected to impose much greater health expenditures, with total expenses to treat resistant bacterial infections alone reaching $412bn annually up to 2035. Increased morbidity and mortality from these infections will lead to lower workforce participation and productivity losses of $443bn/ year,’ the GLG report says. The World Bank has estimated that up to 0.8% of global gross domestic product could be lost due to AMR by 2050.
What can we do about antimicrobial resistance?
Surveillance and monitoring are an essential part of strategy in dealing with AMR. One recommendation from the GLG is that all countries should strengthen their capacity to support sustainable, sector specific and integrated surveillance systems, and the use of data for action. By 2030, there should be the ability to report quality assured AMR and antimicrobial use surveillance data through global surveillance systems.
Reducing use of antimicrobials to prevent AMR
During early 2024, a European multi-agency study concluded that countries where the consumption of antibiotics in both animals and humans has fallen have also seen a reduction in antibiotic-resistant bacteria. The report from the European Food Safety Authority looked at antimicrobial consumption and occurrence of antimicrobial resistance in bacteria from humans and food producing animals in the European Union. As the time Bernhard Url, European Food Standard Agency executive director commented: ‘Using fewer antibiotics in livestock production pays off. In most countries that reduced antibiotic use, we observed a corresponding decrease in resistance levels. This means that national efforts work. It also highlights the EU’s commitment to the One Health approach, safeguarding both animal and global public health.’ The One Health approach recognises the connection between the health of people and animals.
Developing new treatments to tackle AMR
As well as controlling use of antimicrobials, the development of new treatments is another potential step towards tackling the problem. However, a report from the WHO published in June 2024 indicated that while the number of antibacterial agents in the clinical pipeline had increased from 80 in 2021 to 97 in 2023, there remained an urgent need for innovative agents to treat serious disease, as well as replacing treatments that are becoming ineffective due to widespread use. Indeed, another report, also from the WHO, indicated that antibiotics were over-prescribed for patients suffering from Covid-19. But even though there is a need for innovation in the area of antibacterials, there have been warnings that a fall-off in R&D and investment is reducing the pool of knowledge in the area with many large pharmaceutical companies stepping away from the development of new treatments, leading to what has been described as a ‘deepening crisis in antibiotic R&D’. One of the issues is that clinicians will only prescribe new classes of antibiotics as a last resort, because they are reluctant to see AMR impacting on these treatments too. But that can mean there is less of an incentive for pharmaceutical companies to develop new classes of drugs because not only are they often sold quite cheaply, but they may also not be prescribed as often as other options.
AMR versus the woolly mammoth?
One area of opportunity it to find new molecules with antibacterial properties. Right now, artificial intelligence is at the forefront of many of these initiatives. For example, researchers have used algorithms to trawl genetic databases looking for molecules with potential antimicrobial properties. This has included investigating the DNA of our extinct close relatives, the Neanderthals and the Denisovans. It also involves searching the ‘extinctome’ - 208 extinct organisms with sequenced genomes which include the woolly mammoth, the extinct straight-toothed elephant and giant elk - in order to find promising candidates.
Where does the fight against AMR go next?
Many governments and agencies are building a strategy to tackle AMR. The UK has a 20-year vision for tackling AMR through a series of five-year ‘national action plans’ which aim to bring together organisations across government to contain, control and mitigate AMR by 2040. The US has a National Action Plan for Combating Antibiotic-Resistant Bacteria. Most recently, a declaration by global leaders committing to a clear set of targets and actions to tackle antimicrobial resistance (AMR) was been finalised at the 79th United Nations General Assembly High-level Meeting on Antimicrobial Resistance held in New York in September 2024.
Amongst other things, the declaration calls for sustainable financing and $100m in catalytic funding to help at least 60% of countries achieve funded national action plans for AMR by 2030. The journey to the declaration began in 2016 when, for the first time, heads of state gathered with the aim of taking a broad coordinated approach to address the root causes of AMR across multiple sectors. AMR is only the fourth health issue taken up by the UN General Assembly the others were HIV, non-communicable diseases and Ebola. Other collaborative projects include one between UNEP and the Indian Council of Medical Research which is aimed at recognising and addressing the environmental dimension of AMR.
Further reading:
Antimicrobial resistance: New research networks take aim at global health threat
Expert warns of ‘deepening crisis’ in antimicrobial resistance research
WHO warns of pressing need for new antibacterials
New treatments and global research agenda for AMR
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