By Manal Mohammed, Senior Lecturer, Medical Microbiology, University of Westminster.
Antibiotic resistance is often associated with hospitals and the overuse of antibiotics in agriculture. Both are genuine problems, but new research suggests another potential culprit that many people haven’t considered – droughts caused by climate change.
A recent study published in the journal Nature Microbiology found that when soil dries out, it can speed up the natural processes that create and spread antibiotic resistance. This doesn’t mean drought directly creates superbugs in hospitals, but it suggests climate change could make the problem worse.
This matters a lot for the UK. The Met Office predicts that summers will get hotter and drier, with longer droughts if emissions stay high. Meanwhile, the NHS is already struggling with antibiotic-resistant infections, which are harder to treat and keep patients in hospital longer. When standard antibiotics stop working, doctors are sometimes forced to use powerful alternatives that are kept in reserve precisely because overusing them risks making those resistant too. These are known as “drugs of last resort”.
So what’s actually happening in the soil? Soil is teeming with bacteria, and many of them naturally produce antibiotics to kill off rivals. Other bacteria carry genes that make them resistant to those attacks.
An arms race in the soil
In normal, moist soil, bacteria live in a relatively stable environment. But when soil dries out, water gets squeezed into tiny, isolated pockets. Bacteria get crowded together, nutrients become scarce and competition turns brutal. In these conditions, bacteria produce more antibiotics to attack each other, and more resistance genes emerge to help them survive. It’s an arms race fuelled by drought.
Here’s why that’s relevant to human health: bacteria can swap genes with each other through a process called horizontal gene transfer – think of it like sharing a video game cheat code. This means resistance genes from soil bacteria can be picked up by bacteria that infect humans. In fact, some resistance genes found in soil bacteria have already been spotted in bacteria that infect people, hinting at a long evolutionary connection between the two.
Horizontal gene transfer explained.
Some large studies have found that drier regions of the world tend to report higher levels of antibiotic-resistant infections in hospitals, even when taking differences in wealth and healthcare quality into account. However, these studies show correlation, not direct cause and effect. Other factors like how infections are tracked or how easy it is to access healthcare could also explain this pattern.
Some of the soil bacteria linked to this problem are close relatives of hospital pathogens like Klebsiella pneumoniae and Pseudomonas aeruginosa, which belong to a group called Eskape, responsible for many of the world’s hardest-to-treat infections. Again, this doesn’t mean these bugs come from soil, but it does show how connected environmental and clinical bacteria really are.
Antibiotic resistance already causes millions of infections every year worldwide. Most efforts to tackle it have focused on cutting unnecessary antibiotic use in medicine and farming, which is still vital. But this research suggests the environment itself, and how climate change is reshaping it, also plays a role we can’t afford to ignore.
This is where the idea of One Health comes in. One Health is the idea that human, animal and environmental health are all closely linked. Antibiotic resistance, seen through this lens, isn’t just a medical problem, it’s an ecological one too.
As droughts become more common in the UK and around the world, scientists will need to keep a much closer eye on what’s happening beneath our feet.
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