A soil bacterium that breaks down the antibiotic and uses it for growth has been uncovered by researchers.
Bugs exposed to antibiotics for long periods are known to develop resistance to drugs by quickly pumping them out of their cells or modifying the compounds so that they're no longer toxic.
Uncovering a possible mechanism of antibiotic "resistance" in soil, the new research by a group of Canadian and French scientists reports about a soil bacterium that breaks down the common veterinary antibiotic, sulfamethazine, and uses it for growth.
Certain soil bacteria are already known to live off, or "eat", agricultural pesticides and herbicides, said the study leader, Ed Topp, soil microbiologist with Agriculture and Agri-Food Canada in London, Ontario.
In fact, the microbes' presence in farm fields can cause these agri-chemicals to fail, the Journal of Environmental Quality reported.
But to Topp's knowledge, this is the first report of a soil micro-organism that degrades an antibiotic both to protect itself and get nutrition.
"I think it's kind of a game-changer in terms of how we think about our environment and antibiotic resistance," he said, according to an Agri-Food statement.
What the new research suggests, though, is that soil bacteria could be swapping genes for breaking down antibiotics at the same time.
"My guess is that's probably what's happening, but it remains to be determined," Topp said. "It's actually extremely fascinating."
In particular, long-term exposure to antibiotics puts significant pressure on soil bacteria to evolve resistance, which they typically do by giving and receiving genes that let them.