Each year, antimicrobial resistance (AMR) is responsible for an estimated 1.1 to 1.4 million deaths worldwide. Now, scientists have found evidence that the spread of AMR isn’t always driven by bacteria evolving to resist the antibiotics themselves: rather, certain weedkillers can have the same effect.

“Here we show that the most common species of multidrug-resistant bacteria from hospitals are not only resistant to multiple antibiotic classes, but also to high concentrations of the weedkiller glyphosate,” said Dr. Daniela Centrón, a researcher at the Institute of Medical Microbiology and Parasitology in Buenos Aires and the senior author of the study in Frontiers in Microbiology.

“These results suggest that weedkillers—which, unlike antibiotics, are widely applied in agricultural environments—may have the unintended side effect of selecting for AMR among bacterial communities within the soil.”