TORONTO - Chicken meat may be a source of E. coli bacteria that is making its way into people and causing infections, a new study suggests.

The study compared strains of E. coli bacteria in poultry and other meats to the strains found to have been causing urinary tract infections in women in Montreal from June 2005 to May 2007.

While there was some similarity between strains in pork, the association was most noticeable in chicken, the researchers reported.

The findings suggest chicken may be a reservoir for the bacteria and a vector -- a transmitting agent -- for spreading them to humans.

Senior author Amee Mangus said some of the strains are resistant to multiple antibiotics, a worrisome development likely due to the heavy use of the drugs in agricultural operations.

"It's just raising another caution flag to suggest that these E. coli that are not just causing diarrhea, that are causing infections in other areas of our body, they may be acquiring drug resistance through the use of drugs in our food animal production," she said in an interview from Montreal, where she is an infectious diseases epidemiologist at McGill University.

"And I guess it's just another reason for the public health authorities, for the public to ... start questioning a little bit the way we produce our food."

The study is being published in the March issue of the journal Emerging Infectious Diseases. It follows on work the same group published in that journal in 2010 that showed that E. coli can be found in meat.

The earlier study looked at a variety of meats purchased in stores, but with a heavy emphasis on chicken, based on the hunch E. coli would be found there. This time, the researchers looked more broadly at strains found in beef, pork and chicken, but found the strains from chicken were indeed most like those in people.

They were looking at regular E. coli bacteria, not the dangerous 0157:H7 strain behind the Walkerton, Ont., outbreak in 2000.

E. coli bacteria live in the intestines, sometimes without causing any illness. But they can trigger diarrhea. As well, under certain circumstances, they are able to move to the urinary tract and cause painful infections there -- mainly in women. They can also cause bloodstream infections.

"So those E. coli are just waiting in our intestines ready to cause an infection. And the source of those E. coli may actually be the food that we eat," Mangus said.

She and colleagues looked at strains of the bacteria retrieved from the guts of animals as well as from commercial meat. That gave them more confidence the source of the E. coli was the animals. If the bugs had simply been found on the meat itself, one would have to question whether people working in abattoirs had inadvertently contaminated the meat with E. coli they were carrying.

E. coli bacteria are killed by proper cooking. But the presence of the poultry strains in people suggest meat-handling practices are not ideal, Mangus said.

"Improving our kitchen hygiene, preventing cross-contamination, making sure our meat is cooked properly -- all of those things will most certainly protect you against acquiring these E. coli, if in fact this is the way it's happening."