Nearly one in five urinary tract infections in a group of patients in Southern California were linked to E. coli from contaminated meat, a four-year study found. And researchers say the problem could be occurring across the United States.
The researchers found 18% of the more than 2,300 urinary tract infections, or UTIs, in the study — published in the mBio journal on Thursday — were linked to E. coli strains found in meat samples from grocery stores in the same area. The meats most commonly found to test positive for E. coli were turkey and chicken, followed by pork and beef, the study found.
The finding reframes contaminated chicken, turkey, pork, and beef as more than food safety nuisances. UTIs are common infections that happen when bacteria enter the urethra and infect the urinary tract, according to the Centers for Disease Control and Prevention. They disproportionately affect female and elder patients, the CDC said. While most UTIs resolve with antibiotics, severe infections can reach the kidneys or bloodstream and become life-threatening.
“It’s pretty frequent, one in five, and with better food safety, we could reduce it,” Lance Price, a professor of environmental health at George Washington University and one of the study’s authors, told CBS News.
Tracing infection through genomic fingerprints
The researchers used “genomic attribution,” comparing the DNA of E. coli from patients with strains found in meat to estimate how many infections come from animals. After analyzing thousands of bacterial genomes, they found that about 18% of cases carried an animal-linked genetic fingerprint, and roughly 21% in lower-income ZIP codes.
Turkey was the most frequently contaminated meat, followed by chicken, pork, and beef. Price said the socioeconomic pattern echoed what he’d seen in earlier fieldwork.
“In grocery stores in poorer neighborhoods, I found chicken packages pumped with saline, and that liquid can spread bacteria all over,” Price said. “It adds weight, but it may also be making people sick.”
The team also found higher contamination rates in large, low-cost “value packs.” Whether that reflects processing practices or retail handling remains unclear, but the pattern suggests consumers with fewer options may face higher exposure risks.
Experts interpret the findings
Tara Smith, a professor of infectious disease epidemiology at Kent State University who was not involved in the study, said the research was “pretty convincing” at showing “that at least some of these E. coli infections are coming from animals.”
“When you’re exposed to these organisms, by handling raw meat or eating it undercooked, they can take up residence in your gut and stay there,” she explained. “Most UTIs come from your own gut flora. When that flora includes bacteria from animals, that’s the connection.”
Meanwhile, Betsy Foxman, a professor of infectious disease epidemiology at the University of Michigan, urged caution in interpreting the results.
“Sure, it’s plausible,” she said, “but how much do we have to worry about it?”
Foxman questioned whether the 18% figure might be high, noting that UTIs vary by age, sexual activity, hormones, and other factors.
“The real evidence would be a foodborne outbreak of UTIs tied to a specific product,” she said, though she agreed the study adds to mounting evidence that bacteria from food animals circulate more widely than most people realize.
When contamination tracks with ZIP code
People living in low-income areas had a 60% higher risk of foodborne UTIs compared to those in wealthier neighborhoods, according to the study.
Though the reasons for the strong correlation between poverty rate and foodborne UTIs are unclear, the authors say possible factors include inadequate food safety regulations, poor retail conditions and improper food handling and hygiene practices. Foxman said that context matters.
“You have to ask whether people have access to care, whether they can store food safely, and what kind of products are reaching those markets,” she said. “Without that granularity, it’s hard to know what’s really driving these differences.”
Price added these findings show why there should be more investments, not less, in research about the social determinants of health.
“We’re trying to understand why this clustering happens,” he said. “It could be product quality, handling, or inspection, but clearly something systemic is going on.”
The animal origins of everyday infections
For Price, the research underscores how human, animal, and environmental health intersect. The same E. coli lineages that infect people also afflict livestock.
“If we eliminated these bacteria in animals, by vaccine or whatever, you’d probably have mutual benefit,” he said.
The study also exposes how farming and policy decisions ripple through the food chain. Although the U.S. banned antibiotics for growth promotion, farms still use them to prevent disease in crowded barns. “Those animals can develop resistance,” Smith said, “and when humans are later exposed, sometimes the drugs don’t work.”
Price argues that regulators should treat E. coli in meat as a serious health hazard. Stronger slaughterhouse hygiene, stricter contamination standards, and better inspection could all help. Vaccinating animals against the strains most often found in human UTIs could protect both animals and people.
Food safety starts at home, but doesn’t end there
None of the experts advocate panic or abandoning meat altogether. As Smith noted, vegetables fertilized with manure can carry similar bacteria. The message is not abstinence but awareness: treat all raw meat as contaminated until cooked. Handwashing, sanitizing cutting boards, and avoiding splatter from packaging remain the most practical defenses.
“Don’t stop eating chicken or beef,” said Foxman. “Just cook it well and keep your kitchen clean.”
Smith said the study underscores how food handling shapes everyday health.
“You can’t always prevent UTIs once they’re in your body,” Smith said. “But you can be vigilant about how the bacteria get there in the first place. Wash your hands. Keep your kitchen clean. Cook meat thoroughly.”
Still, Price insists that consumers shouldn’t shoulder the blame alone. Regulators and industry leaders are “not going to do anything if they don’t acknowledge the risk,” Price said.
“But if they do, they can develop systems to prevent these bacteria from getting into the food supply,” he continued.
