The climate crisis is accelerating the global rise in antibiotic resistance, posing a serious threat to human health, figures show, showing a rise in antibiotic resistance genes in Salmonella bacteria, experts say.
Antibiotic resistance is one of the fastest growing threats to global health. It can affect people of all ages in any country, and estimates say it already kills more than 1 million people a year.
A study led by researchers from the UK, France, Australia, Switzerland and China has revealed how climate change is linked to rising antibiotic resistance in Salmonella enterica, one of the world’s most common bacterial diseases.
Climate change is associated with a 10% increase in Salmonella antibiotic resistance genes globally between 1940 and 2023, according to a first-of-its-kind study published in The Lancet Planetary Health.
The main driver of antibiotic resistance remains the misuse and overuse of antibiotics used to treat infections. But research suggests the problem is being exacerbated by climate change.
“Accumulating evidence suggests that climate change is an accelerating force behind the global spread of antimicrobial resistance,” the study authors wrote.
“Our findings provide supporting evidence that increasing temperatures and changing precipitation patterns nonlinearly amplify the abundance and spread of antimicrobial resistance genes in bacterial pathogens such as Salmonella enterica.
“These findings support the idea that climate change alters the ecological stability of microorganisms and accelerates the evolution of resistance across human, animal, and environmental reservoirs.
“To reduce the burden of future antimicrobial resistance, urgent integration of climate change mitigation policies, particularly those in line with the Paris Agreement that strengthen antimicrobial stewardship and One Health surveillance, is essential.”
Antibiotic resistance is primarily caused by the overuse or misuse of antibiotics, which allows resistant bacteria to survive and spread. But rising temperatures and changing rainfall patterns could affect bacterial survival, mutation and spread, leading to increased exchange of antibiotic resistance genes, the researchers said.
Previous studies have linked rising temperatures to increased levels of resistant bacteria, but to date there has been limited quantitative research into this association globally.
The new study analyzed the genomes of more than 480,000 Salmonella samples from 139 countries collected between 1940 and 2023. Levels of antibiotic resistance genes were compared to changes in average temperature and precipitation over time.
The researchers used models to study this relationship and found that not only did antibiotic resistance steadily increase with increasing temperature, but the number of resistance genes changed in a more complex manner over time, depending on both temperature and rainfall.
The researchers say this suggests that changes in the environment may speed up the rate at which bacteria adapt to antibiotics.
The study found that Salmonella antibiotic resistance genes are increasing in 82% of the countries surveyed. The Middle East and North Africa saw the most climate-related increases, followed by South Asia and sub-Saharan Africa.
The study showed a link between climate change and Salmonella’s antibiotic resistance genes, but did not prove that climate change is directly causing the increase in Salmonella. However, the authors said their findings highlight the need to consider climate change in global efforts to tackle antibiotic resistance.
They added that urgent action, along with responsible antibiotic use and improved disease surveillance, will be key to limiting the spread of antibiotic resistance in the future.
Their study provided “robust evidence” that climate change is associated with an increased risk of antibiotic resistance, the researchers said.
“The findings highlight that climate change mitigation efforts, combined with antibiotic stewardship, including adherence to low-emissions scenarios, may effectively curb the spread of antimicrobial resistance genes and the rise in global antimicrobial resistance.”
