Superbug Dangers in Chicken Linked to 8 Million At-Risk Women

A growing number of medical researchers say more than 8 million women are at risk of difficult-to-treat bladder infections because superbugs - resistant to antibiotics and growing in chickens - are being transmitted to humans in the form of E. coli.

"We're finding the same or related E. coli in human infections and in retail meat sources, specifically chicken," said Amee Manges, epidemiologist at McGill University in Montreal.

If the medical researchers are right, this is compelling new evidence of a direct link between the pervasive, difficult-to-cure human disease and the antibiotic-fed chicken people buy at the grocery store.

"What this new research shows is, we may in fact know where it's coming from. It may be coming from antibiotics used in agriculture," said Maryn McKenna, reporter for Food & Environment Reporting Network.

The research is part of a joint investigation by ABC News and Food and Environment Reporting Network.

The Food and Drug Administration says 80 percent of all antibiotics sold in the United States are fed to livestock and even healthy chicken to protect them from disease in cramped quarters. It also helps the chickens grow bigger and faster.

"We're particularly interested in chickens. They, in many cases, are getting drugs from the time that they were in an egg all the way up to the time they are slaughtered," Manges said.

The chicken industry says there could be other factors such as overuse of antibiotics by humans. And the industry cautions that there's no study that has proven a superbug from poultry transfers directly to humans.

Researchers point out that a study like that would be unethical because it would require intentionally exposing women to the bacteria. They say that there is persuasive evidence that chicken carries bacteria with the highest levels of resistance to medicine.

Adrienne LaBeouf, 29, is one of the 8 million women suffering from a constant infection. "It feels like I have some kind of infection that just won't go away," she said.

LaBeouf has visited her doctor about her persistent bladder infection. "It was cured for a little while," she added, "and then it comes back with a vengeance."

ABC News' Brian Hartman contributed to this report.