Researchers have identified a surprising cause of some urinary tract infections: contaminated meat.
A four-year study found that nearly 1 in 5 UTIs detected among a group of patients in Southern California were most likely caused by the consumption of chicken, turkey, pork or beef that carried E. coli bacteria.
The common understanding is that most UTIs are caused by improper hygiene or sexual contact. Around 6 million to 8 million cases are recorded in the United States every year, and around 80% are caused by E. coli bacteria. But the strains responsible for the majority of UTIs are not the ones typically associated with foodborne illnesses, which cause diarrhea and vomiting.
The new research, published Thursday in the journal mBio, hints at the prevalence of foodborne UTIs, which were largely unknown to scientists two decades ago.
“This is the latest in a long series of studies that have shown that we’re getting some of our urinary tract infections from food,” said Dr. Martin Blaser, a microbiologist at Rutgers University, who was not involved in the research.
“A study like this allows people to draw inferences, to understand what’s going on,” he added. “If somebody develops a urinary tract infection, they’re now wondering, ‘Well, was it the hamburger I ate three days ago or five days ago?’”
When E. coli bacteria from food wind up causing a UTI, they first enter the gut after people touch contaminated meat in the cooking process or eat undercooked meat. From there, the bacteria can get into the urethra as a result of poor hygiene or improper wiping in the bathroom, then ascend into the urinary tract.
One of the study’s authors, Lance Price, a professor of environmental and occupational health at George Washington University, said he was inspired to investigate the link between UTIs and contaminated meat about 15 years ago, when he noticed that most of the chicken and turkey he tested carried the bacterium.
“For some reason, that was basically being ignored. If it didn’t cause diarrhea, it was being ignored. And so that started me on this path,” he said.
Price’s previous research estimated, based on modeling, that foodborne E. coli could account for up to 640,000 UTIs in the United States every year — around 8% of the total.
His new findings come from a collaboration with researchers at Kaiser Permanente, who collected more than 2,300 urine samples that were positive for E. coli in Southern California from 2017 to 2021. They also took more than 3,300 samples from meat sold in major grocery stores in the area over the same period.
A lab at George Washington University then analyzed the genetic material to determine the origins of people’s infections.
“Strains have different DNA signatures, and you can see whether the strains in the animals and the strains in the people match up or not. And they found a number of matches,” Blaser said.
Among the meat sampled, contamination rates were highest in chicken and turkey products.
The study also found that low-income neighborhoods in Southern California had a 60% higher risk of foodborne UTIs than wealthier neighborhoods. Price and his co-authors suggested that grocery stores in those areas might not have proper storage temperatures or that they may keep products out for too long.
Price said he has seen poorly packaged meat sold in some stores in Washington, D.C.
“I would buy these packages of chicken that were just bloated, just so full of saline that when I put it on the conveyor belt … it would just be wet,” he said. “And I know what’s in that liquid: It’s bacteria, and often drug-resistant bacteria, that’s spilling onto these conveyor belts.”
Urinary tract infections can cause painful and frequent urination, and if they are left untreated, they can lead to serious or life-threatening complications, so people with suspected UTIs should seek treatment right away.
“The bladder is a major gateway to the bloodstream for E. coli. And when you get these E. coli in your blood, they can kill you,” Price said.
Doctors treat UTIs with the same antibiotics regardless of whether the E. coli originated from contaminated meat or another source. (Doctors and patients rarely know the source of an infection, Price said.)
Although thoroughly cooking meat and poultry can kill bacteria, Price said, the transmission of foodborne E. coli is mostly due to cross-contamination in the kitchen, so it is important to keep raw meat separate from other items and wash your hands thoroughly after you prepare food.
His study also recommends that meat producers and regulatory agencies consider stricter measures to limit E. coli contamination, such as making sure packages are sealed tightly and do not contain excess liquid.
“Everybody should have leak-proof packaging in the United States,” he said.
