Glyphosate and Antibiotic Resistance: A Growing Concern
New research from Argentina suggests a potential link between the widely used herbicide glyphosate and the rise of antimicrobial resistance (AMR), a critical global health threat. The study, published in Frontiers in Microbiology, adds to a growing body of evidence indicating unintended consequences of widespread herbicide use.
Glyphosate’s Impact on Bacterial Resistance
Researchers at the University of Buenos Aires assessed glyphosate resistance in bacteria collected from both environmental sources – soil in a nature reserve in the Parana delta, an agricultural region – and clinical settings, specifically Argentinian hospitals. The study focused on 68 bacterial isolates from the nature reserve and 19 multidrug-resistant (MDR) bacterial species commonly found in hospitals, including Enterobacter cloacae.
Previous research has demonstrated that exposure to glyphosate can create selective pressure favoring antibiotic-resistant bacterial strains in soil. However, the connection to pathogens causing human infections remained less clear. This new study suggests a potential pathway for that connection.
Findings: Shared Resistance Mechanisms
The hospital bacteria were, as expected, resistant to multiple antibiotics and likewise exhibited high resistance to glyphosate and glyphosate-based herbicides. Environmental bacteria showed varying levels of glyphosate resistance, with the most resistant strains closely related to those found in the hospitals.
A phylogenetic analysis revealed that the environmental strains with the highest glyphosate resistance clustered near the MDR strains from hospitals. Whole-genome sequencing further indicated that the most glyphosate-resistant environmental isolates possessed a greater number of genetic mechanisms also associated with AMR.
The Unintended Consequences of Herbicide Use
“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,” explained Daniela Centron, PhD, the senior author of the study, in a press release.
The study highlights the potential for glyphosate to act as a co-selective agent, meaning it doesn’t directly cause antibiotic resistance but creates conditions that allow resistant bacteria to thrive. This is particularly concerning given the extensive use of glyphosate in agriculture worldwide.
Broader Implications and Future Research
The researchers emphasize the need for further investigation to fully understand the complex relationship between glyphosate exposure and AMR. They suggest that the potential for AMR development should be incorporated into environmental risk assessments of glyphosate and other biocidal agents.
Argentina is a major consumer of glyphosate, particularly in its genetically modified (GM) soy belt, where agrochemicals are deeply integrated into farming practices. Research indicates that the country’s agricultural landscape is intimately entwined with agrochemicals, impacting the lives and livelihoods of producers.
The findings from this study add to the growing body of evidence suggesting that the widespread use of herbicides may have far-reaching and unintended consequences for public health, including the acceleration of antimicrobial resistance. Further research is crucial to mitigate these risks and protect the effectiveness of antibiotics.