An analysis has found that climate change is associated with a 10 per cent increase in antibiotic resistance genes in salmonella bacteria.

Findings published in The Lancet Planetary Health journal show that 82% of the countries studied saw increases in antibiotic resistance genes in salmonella, an enteric bacteria that can cause food poisoning and typhoid fever, with the strongest climate-associated increases occurring in the Middle East and North Africa, followed by South Asia, and Sub-Saharan Africa.

Bacteria develop antibiotic, or antimicrobial, resistance when they become immune to the very drugs designed to kill them.

Researchers, including those from the Chinese Academy of Sciences, also found that antimicrobial resistance, or AMR, does not just increase steadily with rising temperatures, but that the number of resistance genes changes over time in a more complicated way depending on both temperature and rainfall.

The result suggests that environmental changes can speed up how bacteria adapt to antibiotics, they said.

The analysis of more than 480,000 samples of salmonella genomes collected between 1940 and 2023 from 139 countries and regions also showed that the global average abundance of antibiotic resistance genes in Salmonella has increased by 38 per cent during the study period.

"Climate change is associated with a 10 per cent global rise in the abundance of salmonella ARGs (antimicrobial resistance genes), with increases observed in 82 (82 per cent) of 100 countries," the authors wrote.

Studies have shown a link between how an intensifying climate change can fuel antibiotic resistance, suggesting that increasing temperatures and more frequent extreme weather events can increase prevalence of infectious diseases and the need for antibiotics and antimicrobials for treatment.

The study also modelled how antibiotic resistance genes in salmonella change by 2100 under varied climate emissions scenario.

Results suggested that if countries meet low-emission climate targets and strengthen efforts to use antibiotics responsibly, levels of resistance genes could be 24 per cent lower, compared to the highest-emission scenario.

The authors said the findings highlight the need to consider climate change when monitoring and addressing AMR.

They added that a stronger climate action, alongside responsible antibiotic use and an improved disease surveillance across humans, animals, and the environment, will be important in limiting the future spread of AMR.