🦠 Glyphosate promotes superbugs

One of the most widely used herbicides in the world could help dangerous bacteria survive antibiotic treatments. Each year, antimicrobial resistance contributes to more than one million deaths. Researchers suggest that glyphosate-based herbicides play a role in this phenomenon.

To understand this link, scientists collected 68 bacterial strains from a protected wetland in Argentina, near agricultural fields treated with glyphosate. They also collected 19 strains from local hospitals and 15 others from farms and soils exposed to herbicides. The goal: to measure their resistance to 16 common antibiotics as well as to pure glyphosate and glyphosate-based herbicides.


The results show that hospital strains, already resistant to several antibiotics, also tolerate high concentrations of glyphosate. About 74% of them are resistant to carbapenems, a class of powerful antibiotics used as a last resort. All hospital strains show a high tolerance to glyphosate, which worries researchers: if these bacteria reach wastewater, they could proliferate in treated agricultural areas.

As for environmental bacteria, they also show strong resistance. In the Paraná Delta, where no herbicide is used in the reserve, genera such as Acinetobacter and Pseudomonas show marked resistance to glyphosate. Enterobacter strains tolerate up to 80 mg/mL of glyphosate. In contrast, soil Bacillus are very sensitive to the herbicide. This indicates natural selection linked to herbicides.

The genetic tree of the 102 strains allowed the team to discover that the most glyphosate-resistant bacteria are often closely related, regardless of their origin. The same genera are found in hospitals, fields, and the reserve. This indicates a possible exchange of resistance genes between these environments via the water cycle.

Glyphosate remains controversial: classified as a probable carcinogen by the IARC, it is banned for domestic use in several European countries. The authors recommend that any pesticide be tested for its ability to promote antibiotic resistance before it is marketed.