For decades, farmers have relied on small but continuous doses of antibiotics—sometimes the same ones used to treat humans—to help animals grow. It’s unclear exactly why it works, but it does.
These doses also create antibiotic-resistant bacteria that could spread to humans. For example, resistance to colistin, an antibiotic saved as a last resort in humans, may have spread through its use in pig farming.
By the late 2000s, this practice was widespread but still poorly documented. In 2009, the Food and Drug Administration began collecting data on sales of these drugs for food-producing animals.
The numbers have gone up and up every year—until now. The 2016 report, released Thursday, shows a 14 percent drop in sales of medically important antibiotics from the previous year. “It’s very positive to see this trend,” says Karin Hoelzer, who works on antibiotic resistance for the Pew Charitable Trusts.
This year’s report could just be the beginning. In January of this year, the FDA implemented a policy three years in the making: It asked manufacturers to stop selling antibiotics important for human medicine, such as penicillin and tetracycline, for growth promotion in animals. So the sales numbers will likely drop further in the next report.