Antibiotic Resistance Found in Crows and Other Wildlife

Human-derived drug resistance is being found where it shouldn't be.


| Fall 2014



A crow sips water

What's alarming, say the researchers, is that some of the vancomycin-resistant bacteria in the crows were resistant to several other antibiotics widely used in human medicine and livestock feed.

Photo by Flickr/Brian Uhreen

One afternoon in the winter of 2012, Julie Ellis unfurled a long, white tarp under a stand of trees near Coes Pond in Worcester, Massachusetts, where hundreds of crows roost. Her mission: to collect as much bird poop as possible.

Back in the laboratory, Ellis’ colleagues combed through the feces. Testing its bacteria, they discovered something unusual—genes that make the crows resistant to antibiotics.

Drug-resistant infections are a fast-growing threat to human health, due largely to overuse of antibiotics in human medicine and livestock production, according to the Centers for Disease Control and Prevention. At least 2 million people each year in the United States alone are sickened by infections resistant to drugs.

Now new research, including the crow poop study conducted in four states, provides evidence that antibiotic resistance has spread beyond hospitals and farms to wildlife.

Some experts worry that contaminating wildlife with such genes may hasten the spread of drug resistance. Nevertheless, the consequences for human health remain poorly understood. “We’ve documented human-derived drug resistance where it shouldn’t be—in wildlife and the environment. But we know very little about how this may impact public health. There just isn’t that smoking gun,” said Ellis, a research scientist at Tufts University’s veterinary school.