Researchers in Argentina found that multidrug-resistant hospital bacteria also resisted glyphosate, raising concerns that heavy agricultural herbicide use may help antibiotic-resistant organisms persist and spread outside medical settings.
By yourNEWS Media Newsroom
A new study published June 23 in Frontiers in Microbiology suggests that glyphosate, one of the world’s most widely used herbicides, may contribute to the selection and spread of antibiotic-resistant bacteria beyond hospitals and into soil, water and agricultural environments.
Researchers at the Institute of Medical Microbiology and Parasitology in Buenos Aires analyzed 102 bacterial strains from three different settings: 68 from sediment in a protected nature reserve in Argentina, 19 from local hospitals and 15 from agricultural sites and feedlots where herbicide exposure was present.
The study found that multidrug-resistant bacteria collected from hospitals also showed high resistance to glyphosate. The findings add to concerns that antimicrobial resistance, long associated with antibiotic overuse in medicine and agriculture, may also be influenced by exposure to weedkillers in the environment.
Dr. Daniela Centrón, the study’s senior author, said the results point to a possible pathway by which herbicides could place selective pressure on bacterial communities.
“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,” Centrón said.
Antimicrobial resistance, or AMR, has been declared a global health crisis by the World Health Organization. Public health data estimate that AMR contributes to 1.1 million to 1.4 million deaths worldwide each year.
In the United States, more than 2 million people are infected with antibiotic-resistant bacteria annually, according to the Centers for Disease Control and Prevention. Although medical overuse of antibiotics remains a major factor, agriculture also plays a significant role. Agricultural usage accounts for about 80% of all antibiotic use in the United States, making it an important source of antibiotic exposure linked to human health.
Glyphosate was first registered in the United States in 1974 and remains an active ingredient in professional and agricultural Roundup products. The International Agency for Research on Cancer has classified glyphosate as a probable human carcinogen, and several European countries have restricted its household use.
The herbicide is widely used in farming, landscaping and commercial settings. Researchers said its environmental persistence raises questions about whether repeated exposure could favor bacteria that are also resistant to important antibiotics.
For the study, researchers tested bacterial strains from the Paraná delta nature reserve, where herbicides had never been applied. They compared those samples with strains from local hospitals, including multidrug-resistant species, and with samples from feedlots and agricultural soils affected by herbicide use.
The team evaluated resistance to 16 commonly used antibiotics, including last-resort drugs such as carbapenems, along with resistance to pure glyphosate and glyphosate-based herbicides.
All 19 hospital-derived strains were resistant to glyphosate, according to the study. Among those hospital strains, 74% were also resistant to carbapenems.
Environmental strains taken from the protected reserve also showed glyphosate resistance, though tolerance levels varied by bacterial type. Enterobacter species tolerated up to 80 mg/mL, while Bacillus species were inhibited at 2.5 mg/mL.
Dr. Camila Knecht, the study’s first author, said wastewater could provide one route for resistant bacteria to move from health care settings into the broader environment.
“If these bacteria enter the environment through untreated wastewater from hospitals, they could go on to thrive in agricultural areas where glyphosate is used,” Knecht said.
Genetic analysis showed that the bacteria with the highest glyphosate resistance were closely related across hospital, agricultural and protected-reserve samples, according to the researchers. The same bacterial genera displayed glyphosate resistance in all three settings.
Coauthor Dr. Jochen A. Müller said the water cycle likely helps move antibiotic resistance genes between hospitals and agricultural environments. Researchers said the findings are consistent with observations from a remote Himalayan village, where a polluted river contained antibiotic-resistant bacteria surviving in water contaminated by pesticides and hospital waste.
The study adds to evidence that antibiotic resistance can spread far beyond medical facilities. Researchers have also noted concerns that genetically engineered crops can involve antibiotic-resistance marker genes used when foreign proteins are inserted into plants, creating another possible environmental source of resistance genes.
The combination of glyphosate exposure and resistance genes in the environment may create areas where superbugs can evolve, the report stated.
The findings could carry regulatory implications for pesticide approval and labeling. France, Belgium and the Netherlands have banned glyphosate for household applications, while Germany prohibits its use in public spaces, according to reports. Former congressman Dennis Kucinich has said the United States has some of the most lenient regulations on pesticide contamination compared with other countries.
Centrón said pesticide regulations should require testing for co-selection with antibiotics before products reach the market. She also recommended warning labels stating that genes for antibiotic resistance can spread from glyphosate-contaminated soils to hospitals through untreated water.
Researchers and advocates have pointed to regenerative agriculture as one way to reduce dependence on synthetic chemicals by improving soil health. Growing organic food has also been presented as one way consumers can reduce exposure to antibiotic-resistant superbugs.
The study’s findings add urgency to calls for a broader review of widespread herbicide use in agriculture and its possible connection to the global rise of antimicrobial resistance.
Source: Natural News
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