Dr. Jehan El-Bayoumi, LeBeouf's physician and an associate professor of medicine at George Washington University Medical Center, said she has seen "a really significant increase, especially within the past two to three years."

But the origin of these newly resistant E. coli has been a mystery -- except to a small group of researchers in several countries. They contend there is persuasive evidence that the bacteria are coming from poultry. More precisely, coming from poultry raised with the routine use of antibiotics, which takes in most of the 8.6 billion chickens raised for meat in the U.S. each year.

Their research in the United States, Canada, and Europe (published most recently this month, in June, and in March) has found close genetic matches between resistant E. coli collected from human patients and resistant strains found on chicken or turkey sold in supermarkets or collected from birds being slaughtered. The researchers contend that poultry -- especially chicken, the low-cost, low-fat protein that Americans eat more than any other meat -- is the bridge that allows resistant bacteria to move to humans, taking up residence in the body and sparking infections when conditions are right. Touching raw meat that contains the resistant bacteria, or coming into environmental contact with it -- say, by eating lettuce that was cross-contaminated -- are easy ways to become infected.

"The E. coli that is circulating at the same time, and in the same area -- from food animal sources, retail meat, and the E. coli that's causing women's infections -- is very closely related genetically," said Amee Manges, Ph.D., an associate professor of epidemiology at McGill University in Montreal who has been researching resistant UTIs for a decade. "And the E. coli that you recover from poultry meat tends to have the highest levels of resistance. Of all retail meats, it's the most problematic that way."

Policy concern over antibiotic-resistant bacteria -- where they come from and how they affect human health -- is at a peak right now.

About 80 percent of the antibiotics sold in the United States each year are given to livestock as "growth promoters" that allow animals to put on weight more quickly, or as prophylactic regimens that protect against the confined conditions in which they are raised. (That figure, taken from FDA documents, is not universally accepted; the Animal Health Institute, an industry group, puts non-human use closer to 28 percent.) For decades, public health and agriculture have been at loggerheads over the practice. Health officials argue that these uses create resistant bacteria that move off large-scale farms via wind, water, dust, and in the animals themselves and the meat they become -- and create difficult-to-treat human infections. Agricultural interests counter that human infections have far more to do with medical misuse of antibiotics than with farming, and that the cost of stopping the drugs would be too great for producers to bear.