A study in Frontiers in Microbiology reports that bacterial strains linked to hospital infections in Argentina showed high tolerance to glyphosate, a widely used herbicide ingredient, alongside resistance to multiple antibiotics. The authors say the results raise questions about whether herbicide exposure could help select for antimicrobial resistance in the environment, though the research does not establish that glyphosate causes antibiotic resistance in patients.
Scientists in Argentina and Germany examined whether resistance to glyphosate—the active ingredient in many herbicides—overlaps with resistance to clinically important antibiotics.
The team compared bacterial strains collected in and around Buenos Aires, including 19 strains associated with hospital-acquired infections, 68 strains from sediments in a protected nature reserve in the Paraná delta, and 15 strains from feedlots and herbicide-impacted agricultural soils. The researchers tested the strains against 16 antibiotics and measured tolerance to pure glyphosate and a glyphosate-based herbicide.
According to a Frontiers news release summarizing the work, all 19 hospital strains were highly resistant to glyphosate and glyphosate-based weedkillers, and 74% were resistant to carbapenems, a class of broad-spectrum antibiotics often reserved for severe infections.
In genetic comparisons, the researchers reported that the most glyphosate-tolerant environmental strains tended to be phylogenetically related to multidrug-resistant clinical strains, a pattern the paper links to mechanisms such as efflux pumps and other genes that can contribute to survival under chemical stress.
The senior author, Dr. Daniela Centrón of the Institute of Medical Microbiology and Parasitology in Buenos Aires, said the results suggest herbicides may unintentionally help select for antimicrobial resistance in soil bacteria:
“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.”
Coauthor Dr. Jochen A. Müller of Karlsruhe Institute of Technology said the study supports a “One Health” view in which resistant bacteria and resistance genes can move between environmental and clinical settings, with water pathways potentially playing an important role.
The researchers argued that pesticide policy should better account for these kinds of interactions. Centrón called for co-selection testing with antibiotics before pesticides are marketed, and said product labels should warn that antibiotic-resistance genes can spread through untreated water.
