Here's some new dirt on an unusual source of antibiotic resistance

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New dirt on an unusual source of antibiotic resistance New research suggests drought can stoke antibiotic resistance in soil bacteria — and that can have an impact on humans.

Global Health

Here's some new dirt on an unusual source of antibiotic resistance

March 27, 20268:59 AM ET

By

Jonathan Lambert

Soil may be a source of resistance to antibiotics, new research suggests

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What does dry soil, like this stretch in South Africa, have to do with antimicrobial resistance? A new study offers an unexpected hypothesis: drought can drive higher antibiotic resistance in soil bacteria.

Rodger Bosch/AFP/via Getty Images

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Rodger Bosch/AFP/via Getty Images

It's one of the highest-stakes battles on earth: bacteria versus antibiotics.

And in the human realm, bacteria appear to be gaining ground. Worldwide, many antibiotics are starting to lose their bite. About 1 in 6 human infections tested in labs are resistant to antibiotics, contributing to over 4 million deaths a year.

Researchers know that human use, and especially overuse, have given bacteria opportunities to develop resistance. But antibiotics, and resistance to them, are much older than the pills we pop for infections. Both are the product of one of the longest-running battles on Earth, playing out in soil.

"In nature, organisms are duking it out, it's a competitive environment," says Dianne Newman, a microbiologist at Cal Tech. "One of the strategies microbes have evolved to effectively compete is to produce antibiotics, to kill their neighbors."

This evolutionary arms race has been ongoing for millenia. But it's only really mattered for humans since we discovered antibiotics in soil, and started using them to treat infections in the 1940s. Newman wondered whether environmental changes to the ultimate source of antibiotics — soil — might be contributing to this rise, too.

Drought, it turns out, can drive higher antibiotic resistance in soil bacteria, Newman and her colleagues report in Nature Microbiology. That resistance may be working its way into human infections too, the researchers found.

"It's an awesome paper, and shows that drought is already having an impact on health care systems around the world," says Timothy Ghaly, a microbial ecologist at Macquarie University in Australia who wasn't involved in the study. "With drought increasing in many parts of the world, that's likely to increase the prevalence of antimicrobial resistance as well."

Looking to the soil Drought may seem an unlikely candidate for a major driver of antibiotic resistance. But Newman had a hunch that when soil dries up, the antibiotics bacteria use to wage war might become more potent, simply because of evaporation.

"Imagine you have a vat of a liquid and you have a certai