Scientists have long believed that urinary tract infections are typically caused by a person’s own E. coli bacteria, but a new Canadian study suggests the bacteria may more often than not come from chickens.

Yes, chickens.

As many as 85 percent of urinary tract infections are caused by E. coli, according to the report in the March issue of Emerging Infectious Diseases, a publication of the U.S. Centers for Disease Control and Prevention.

Researchers compared the genetic fingerprints of E. coli from these infections to that of E. coli from chicken, beef and pork. And they found a match: chicken. What’s more, they report that the infections probably came directly from the chickens, not from human contamination during food processing.

“Chicken may be a reservoir for the E. coli that cause infections like urinary tract infections,” said study author Amee Manges, who is with the department of epidemiology, biostatistics and occupational health at McGill University in Montreal.

“We are also concerned about the selection and amplification of drug-resistant E. coli on the farms because of improper or overuse of antimicrobials during food animal production. It may be possible to reduce the level of drug-resistant infections in humans by encouraging rational and judicious use of antimicrobials on farms,” Manges said.

“We just want to emphasize that it isn’t just inappropriate use of antibiotics in human medicine that matters, but also the use of antibiotics in veterinary medicine and food production that leads to greater drug-resistant bugs,” the study author added.

The U.S. Food and Drug Administration already advises against the overuse of antibiotics in livestock, because it can lead to resistant strains of bacteria.

Dr. Philip Tierno, director of clinical microbiology and immunology at NYU Langone Medical Center in New York City, said it is not surprising that the food supply, especially chicken, may play a role in causing urinary tract and other infections. He said the best protection begins with proper hygiene.

“If you practice good personal hygiene, good food hygiene and good home hygiene, we can reduce the number of infections,” he suggested. Proper hand washing should last for 20 seconds. “Wash in between your [fingers] and under your nails,” Tierno said. “When dealing with counter surfaces, use a product that can disinfect surfaces and prevent cross-contamination.”

Cooking also helps kill disease-causing bugs. “Eat nothing raw. Cook it well, and if you are eating vegetables, make sure to soak them and wash them well,” he said.

The solution is definitely not to throw more antibiotics at livestock, Tierno agreed. As far as preventing E. coli in chicken coops, “we need a better system developed to raise chickens so they are not raised in crowded conditions and prone to diseases like E. coli,” he explained.

Good hygiene is never a bad idea, but the truth is that E. coli is everywhere, said Dr. Elizabeth Kavaler, a urologist at Lenox Hill Hospital in New York City. “The best defense against urinary tract infections is to exercise, eat well and get proper sleep so your immune system is strong and can fend off what you can’t see, including E. coli,” she said. “Be healthy, wash your hands, take care of yourself and when you have a urinary tract infection, see your doctor for an antibiotic to treat it.”

More information

Learn more about food safety at the U.S. Department of Agriculture.

SOURCES: Amee Manges, Ph.D., M.P.H., department of epidemiology, biostatistics and occupational health, McGill University, Montreal; Philip Tierno, Ph.D., director, clinical microbiology and immunology, NYU Langone Medical Center, New York City; Elizabeth Kavaler, M.D., urologist, Lenox Hill Hospital, New York City; Feb. 15, 2012, Emerging Infectious Diseases, online

Last Updated: Feb. 15, 2012