New Delhi: The impacts of climate change are now reaching a microbial level, allowing bacterial pathogens to grow more resistant to antibiotics, says a recent study published in The Lancet.
Led by researchers from the UK, France, Australia, Switzerland, and China, the study analysed the genomes of Salmonella, a group of bacteria that causes intestinal infections that lead to diarrhoea, fever, and stomach cramps. The analysis of a dataset of 4,88,232 Salmonella genomes from 139 countries over a period from 1940 to 2023 revealed that climate change is associated with a 10 per cent rise in antimicrobial resistance genes (AGR) in the bacteria.
Researchers found that such genes became more abundant due to extreme temperatures, erratic rainfalls, droughts, and other climate events.
“The accumulated evidence suggests that climate change is an accelerating force behind the global spread of antimicrobial resistance,” the study read.
How climate affects bacteria
When antibiotics are misused, the targeted bacteria often die off, but resistant strains survive. These continue to evolve and multiply, eventually becoming bugs that are harder to treat with existing medicines. Research has shown that climate change only speeds up this process.
Higher temperatures allow bacteria to reproduce faster. As their metabolic rates are accelerated, the inner chemistry of bacteria is sped up, which allows them to process food and divide faster. If bacteria are beginning to gain resistance to existing medicines, a warmer climate could help them evolve and proliferate faster, making modern medicines less efficient in a shorter span of time.
Researchers found that extreme rainfall can also speed up antibiotic resistance. Floods and hurricanes often damage sanitation systems and contaminate water supplies. This leads to a dangerous phenomenon in bacteria called ‘horizontal gene transfer’.
In a horizontal gene transfer, a bacterium that comes across a floating piece of DNA can directly absorb it into its own genome. Even two bacteria that come into contact with one another can exchange genetic material through this process.
As researchers analysed the genetic material of Salmonella, they found that not only was antibiotic resistance on the rise, but the number of genes resistant to antibiotics was also growing.
While the study highlights the link between climate change and antibiotic-resistant genes in bacteria, researchers clarified that so far, their observations have shown correlation and not causation.
“The ubiquitous presence of Salmonella across all health sectors and the multifaceted climate-driven impacts on AMR dynamics underscore the importance of monitoring, controlling, and mitigating the escalating global AMR crisis through integrated human–animal–environment interventions,” the study said.
As per conservative estimates, antimicrobial resistance affects nearly 10 lakh people every year.
(Edited by Prasanna Bachchhav)
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