BY MARIA BURKE
Climate change is fuelling a rise in antibiotic-resistant Salmonella, a new global study reports. It found that climate change was associated with a 10% global increase in Salmonella antibiotic resistance genes between 1940 and 2023.
Antimicrobial resistance (AMR) is mainly driven by the over- and misuse of antibiotics, which allows resistant bacteria to survive and spread. However, rising temperatures and changing rainfall patterns can influence how bacteria survive, mutate, and spread, potentially increasing the exchange of antibiotic-resistance genes.
While previous studies have linked higher temperatures to greater levels of resistant bacteria, global quantitative studies on this relationship have been limited.
This study by an international team led by researchers at the Research Center for Eco-Environmental Sciences in Beijing, China, analysed the genomes of more than 480,000 Salmonella samples from 139 countries collected between 1940 and 2023, comparing levels of antibiotic resistance genes with changes in average temperature and rainfall over time.
Using modelling, they found that AMR increases steadily as temperatures rise; and the number of resistance genes changes over time depending on temperature and rainfall, suggesting that environmental changes can speed up how bacteria adapt to antibiotics.
The team reports that 82% of countries studied saw increases in antibiotic resistance genes in Salmonella, with the strongest climate-associated increases occurring in the Middle East and North Africa, followed by South Asia, and Sub-Saharan Africa (Z Zhou et al, The Lancet Planetary Health, 2026, 10).
Further modelling investigated the change in antibiotic resistance genes in Salmonella by 2100 under different emissions scenarios. It suggests that if countries meet low-emission climate targets and strengthen efforts to use antibiotics responsibly, levels of resistance genes could be 24% lower than under the highest-emission scenario.
The authors note that, while the study shows a link between climate change and antibiotic resistance genes in Salmonella, it doesn’t prove that climate change directly causes the increase.
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