Climate change is associated with an increase in antibiotic resistance globally, according to a new study that looks at how environmental factors influence the evolution of pathogenic bacteria.
An international study points to a link between climate change and the rise of antibiotic resistance in several bacteria. The researchers show that rising temperatures and changing rainfall patterns are associated with the expansion of antimicrobial resistance genes, a phenomenon that raises concerns about the evolution of bacterial infections globally.
Antibiotic resistance is one of the fastest growing and most dangerous threats to global health, as it can affect people of any age and in any country and is already responsible for more than one million deaths annually, according to international estimates.
The phenomenon occurs when bacteria become able to survive regular antibiotic treatments, making infections much harder to treat.
10% increase in resistance genes
The study was carried out by an international team of researchers from the UK, France, Australia, Switzerland and China and looked in particular at Salmonella bacteria, one of the most common causes of bacterial infections worldwide.
According to research published in the Lancet Planetary Health journal, climate change is associated with about a 10% increase in antibiotic resistance genes in Salmonella over the period 1940–2023.
Although the main drivers of antimicrobial resistance remain the excessive and inappropriate use of antibiotics, researchers argue that climate change can significantly amplify this phenomenon.
Rising temperatures and changes in rainfall patterns may influence the survival of bacteria, the rate of mutations and how they spread in the environment, scientists say.
“Accumulating evidence suggests that climate change is an accelerating factor in the global spread of antimicrobial resistance,” wrote the study’s authors, pointing out that the relationship between climate and antimicrobial resistance is a complex one, in which the interaction between temperature and precipitation can differentially influence the evolution of resistance genes in pathogenic bacteria.
“Our results provide further evidence that rising temperatures and changing precipitation patterns are nonlinearly amplifying the abundance and spread of antimicrobial resistance genes in pathogenic bacteria such as salmonella“, says the cited study.
The researchers also point out that these climate processes can influence the stability of microbial ecosystems and accelerate the adaptation of bacteria to diverse environments, including human, animal and environmental: “These findings reinforce the idea that climate change is altering microbial ecological stability and accelerating the evolution of resistance in human, animal, and environmental reservoirs.”
Analysis of hundreds of thousands of samples
To carry out the study, the researchers analyzed the genomes of over 480,000 Salmonella samples from 139 countries, collected between 1940 and 2023. These data were correlated with the evolution of average temperatures and precipitation regime at global level.
The analysis shows that 82% of the countries included in the study have seen increases in antibiotic resistance genes in salmonella. The most significant increases linked to climate change were identified in the Middle East and North Africa, followed by South Asia and Sub-Saharan Africa.
The researchers found that the evolution of resistance is not driven solely by rising temperatures, but by a combination of climate factors, including precipitation, suggesting a more complex pattern of evolution than previously assumed.
In conclusion, the authors of the study state that the results provide “strong evidence” for the link between climate change and the increased risk of antibiotic resistance, emphasizing that combined action on the environment and antibiotic use could limit the spread of this phenomenon globally.
