Study links herbicide use to antibiotic resistance

CornSeedling_blogIn one of the first studies of its kind, a group of researchers have found that commonly used herbicides can cause bacteria to become resistant to antibiotics, meaning if someone is exposed to both herbicides and antibiotics at the same time, higher doses of antibiotics will likely be needed to kill the offending bacteria.

The growing risk of disease from antibiotic-resistant pathogens has become a major public health concern, one that was recently prioritized by both the World Health Organization and the US Centers for Disease Control.

The study, published in mBio, the peer-reviewed journal of the American Society for Microbiology, urges policy makers and researchers to look at multiple factors, not just over-use of antibiotics, in fighting antibiotic resistance, according to Jack Heinemann, the study’s lead author. As more genetically modified crops are planted, some use of herbicides is expected to increase as well, he said.

“We were so surprised by what we were seeing. We wanted to be sure it wasn’t an artifact of conditions in our laboratory or some kind of contamination. So we enlisted a fellow researcher who conducted the same experiments but without knowing what she was adding to the bacteria. She got the same results,” Heinemann stated in a recent article.

The study comes a week after glyphosate, the active ingredient in several herbicides, was deemed “probably carcinogenic” by the World Health Organization.

The level of herbicide exposure tested in the research was higher than what would generally be found as residue on food, but lower than application standards for commercially available herbicides, the article states. The level is compatible with the amount that people in rural areas can be exposed to from herbicide drift, which occurs when wind distributes chemicals sprayed in one field across other plots of land.

Heinemann and his fellow researchers tested various combinations of three of the most commonly used herbicides including, dicamba, 2,4-dichlorophenoxyacetic acid, and glyphosate. They also studied five different classes of antibiotics including, ampicillin, ciprofloxacin, chloramphenicol, kanamycin, and tetracycline.

In some cases, certain combinations of herbicide and antibiotic either improved the performance of the antibiotic or had no effect on the antibiotic at all. However, in the majority of cases, the herbicide made the antibiotic less effective.

Based on these results, Heinemann and this team said they know that more research on this topic is necessary and will also explore exposure pathways to determine which may be most relevant to human health, pet health, the health of farm animals and important pollinators such as honey bees.

In the meantime, the study authors are concluding that the current practice of testing herbicides in isolation and not in combination with other herbicides, antibiotics, or other chemicals that are common in the environment, may underestimate their role in the emergence of antibiotic resistance.

For more information, click here.

Comments are closed.