Continuing to treat urinary tract infections as a short-term, routine ailment rather than a long-term food safety issue risks turning the responsible bacteria into a major health crisis.kusabi/Flickr
Adrienne LeBeouf recognized the symptoms when they started. The burning and the urge to head to the bathroom signaled a urinary tract infection, a painful but everyday annoyance that afflicts up to 8 million U.S. women a year. LeBeouf, who is 29 and works as a medical assistant, headed to her doctor, assuming that a quick course of antibiotics would send the UTI on its way.
That was two years ago, and LeBeouf has suffered recurring bouts of cystitis ever since. She is one of a growing number of women, and some men, who have unknowingly become infected with antibiotic-resistant versions of E. coli, the ubiquitous intestinal bacterium that is the usual cause of UTIs.
There is no national registry for drug-resistant infections, and so no one can say for sure how many resistant UTIs there are. But they have become so common that last year the specialty society for infectious-disease physicians had to revise its recommendations for which drugs to prescribe for cystitis -- and many infectious-disease physicians and gynecologists say informally that they see such infections every week.
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.
The U.S. Food and Drug Administration which regulates agricultural use of antibiotics, has been aware for decades of evidence that farm overuse of antibiotics creates resistant human infections, but has done little to help. In 1977, the agency proposed withdrawing its own approvals for penicillin and tetracycline use as growth promoters, and the proposal remained on the books even though the FDA was repeatedly stymied by legislative opposition. Last December, the agency actually gave up, and announced that it was cancelling its then 34-year-old attempts, opting instead for a voluntary approach. But this March, and again in June, a district court judge in New York City ruled the FDA must go through with its original program for re-examining agricultural antibiotic use, including holding hearings to examine the drugs' off-farm effects.
Because UTIs are such an everyday occurrence, rising resistance has not been a major priority for medicine.
The proposed link between resistant bacteria in chickens and those causing UTIs is not the first time researchers have traced connections between agricultural antibiotic use and human illness. But because the UTI epidemic is so large and costly, the assertion that it might be tied to chicken production has brought renewed attention to the issue.
Investigators have been examining a possible link between growth promoters, chickens, and human infections since at least 2001, when Manges and others published in the New England Journal of Medicine an analysis of clusters of UTIs in California, Michigan, and Minnesota. The striking thing at the time was that the clusters appeared to be outbreaks caused by very similar E. coli strains that were resistant to the common drug Bactrim. In the United States, one out of every nine women has a UTI every year. If a single small group of E. coli was causing some proportion of the infections, that would be alarming -- but it might also offer a clue to defusing the overall epidemic. Initially, though, the researchers had no idea where the strains were coming from.
As a follow-up, Manges and other investigators looked for vehicles that might be transporting particular E. coli strains. That was an unusual challenge, because E. coli is one of the most common organisms on the planet, with a huge variety residing in the guts of humans and every warm-blooded animal, and in reptiles and fish as well. The particular subset of strains they examined are called "ExPEC," for "extra-intestinal pathogenic E. coli" -- that is, E. coli that escapes the gut to cause illness elsewhere in the body, including in the urinary tract.
ExPECs were already a medical-research concern, because E. coli that moves from the gut into the bladder may not stay there. Infections that are not treated can climb up to the kidneys and enter the bloodstream. ExPEC E. coli cause up to 40,000 deaths from sepsis -- the most serious form of bloodborne bacterial infection -- in the United States each year, and since about 2000, antibiotic resistance in ExPEC strains has been climbing.
In 2005, University of Minnesota professor of medicine Dr. James R. Johnson published results of two projects in which he analyzed meat bought in local supermarkets during 1999-2000 and 2001-2003. In both cases, he found resistant ExPEC E. coli strains that matched ones from human E. coli infections. Other researchers soon found similar matches in meat--particularly poultry--from across Europe, in Canada, and in additional studies from Minnesota and Wisconsin.