Lauren Fuge
Climate change could contribute to an increase in deaths from antibiotic-resistant bacteria by 2050, according to a new study in Nature Medicine.
Led by researchers from Sun Yat-sen University and Peking University in China, the study shows that rising temperatures, air pollution and extreme weather are likely to make the problem of antimicrobial resistance (AMR) worse – and that this will particularly affect low- and middle-income countries.
“The current measures in response to antimicrobial resistance have largely focused on over use of antibiotics,” says Chaojie Liu, a researcher from the School of Psychology and Public Health at La Trobe University and co-author on the study. “Although it is critical, we have limited understanding about how bacterial develop and spread antimicrobial resistance.
“Our study examined a comprehensive list of potential factors on their associations with antimicrobial resistance, and the results indicate that we need to take a more comprehensive approach in coping with the public health threat arising from antimicrobial resistance.”
What is antimicrobial resistance?
AMR is already a threat to global health, occurring when microorganisms – including viruses, bacteria, fungi and parasites – stop responding effectively to medicine. This makes infections harder to treat and diseases easier to spread, and increases the risk of severe illness and death.
AMR was directly responsible for approximately 1.14 deaths in 2021. By 2050, this is expected to increase to 1.91 million deaths directly from AMR. Cumulatively, this will result in 39 million deaths between now and 2050. AMR disproportionately affects low- and middle-income countries (LMICs).
Researchers have long been calling out the overuse and misuse of antimicrobials, but this is not the only driver of the rise of antibiotic-resistant bacteria. Socioeconomic and environmental factors – like climate change – also play a role.
“Our current understanding about the effects of climate change on AMR is limited,” says Liu. “There are studies establishing the link between climate change and antimicrobial resistance, but the link is not so straightforward.
“For example, some resistant variants have a stronger link with climate change than others. There are also regional variations.”
This new study set out to better understand this link.
Digging deeper
The team drew on 4,502 records from 101 countries of 6 key pathogens resistant to antimicrobials.
“The study reveals strong associations between AMR and factors such as rising temperatures, PM2.5 pollution, water runoff, healthcare spending, and immunisation coverage,” says Liu.
The models took into account different climate change futures by incorporating four Shared Socioeconomic Pathways (SSPs), which project global changes in socioeconomic development up to 2100 based on different levels of greenhouse gas emissions and different climate policies.
Liu explains that the four pathways used were:
- a sustainable development pathway with a low greenhouse gas concentration trajectory;
- a moderate development pathway with an intermediate greenhouse gas concentration trajectory;
- a fragmented world scenario with a high-emission trajectory, portraying a future of regional disputes, prioritising national security over global environmental concerns;
- a fossil-fuel intensive development pathway with the highest greenhouse gas concentration trajectory, imagining a future driven by rapid economic growth reliant on fossil fuels.
The team found that in the worst-case scenario, where global temperatures increase by 4-5°C by 2100, climate change could increase the global burden of AMR by up to 2.4% by 2050, as compared to the low-emission scenario.
But not all countries were equally affected in the forecasts.
In higher-income countries, the AMR burden was increased by 0.9%; in low- and middle-income countries (LMICs), it increased by 4.1%; in lower-income countries, it increased by 3.3%.
“Findings show that AMR trajectories will diverge sharply depending on national development strategies, with LMICs facing especially steep challenges under climate change pressures,” says Liu.
These challenges stem from issues such as poverty, corruption, inadequate sanitation and inadequate testing infrastructure.
“This is particularly important considering the disproportionate impact of climate change on LMICs, despite their lower contribution to climate change,” the authors write in their paper.
Resisting the resistors
So what actions could be taken to manage AMR spread?
“The results indicate that a 50% reduction in antimicrobial consumption could lower AMR by an average of 2.0% by 2050,” Liu says. “However, this reduction is smaller than the potential benefits of sustainable development efforts, which could reduce AMR by 5.4%.”
These short-term sustainable development efforts include lowering out-of-pocket healthcare costs, increasing access to immunisation, better hygiene services, and universal access to clean water.
“Critically, the research underscores that focusing solely on antibiotic overuse is insufficient,” Liu says.
It also emphasises that while short-term efforts are important, global collaboration on management strategies is needed to face the long-term consequences of climate change and human activities on AMR.
“The world needs to work together towards a sustainable development future,” Liu says.
