More than half a million urinary tract infections in the U.S. each year may be caused by E. coli strains from meat products, a new study reported Thursday.
Using a new genomic approach to track the origins of E. coli infections, researchers from George Washington University estimated that 480,000 to 640,000 UTIs may be caused by the foodborne bacteria, according to the analysis published in the peer-reviewed journal One Health.
“There’s lots of studies showing that when most people have a bladder infection, it’s caused by the same kind of E. coli that they have in their gut,” said senior author Lance B. Price, founder and co-director of George Washington University’s Antibiotic Resistance Action Center. “But where do they come from and how do they get into our guts? … We tried to set out and quantify that.”
The findings could have important implications for the country’s food supply and the agencies that regulate it. Here’s what we know.
A urinary tract infection can affect any part of the urinary system, which includes the kidneys, bladder and urethra. UTIs are treated with antibiotics, according to the Mayo Clinic, and women are at greater risk.
UTIs caused by E. coli can range from a simple bladder infection to life-threatening bloodstream infections.
Urinary tract infections cause more than 1 million emergency room visits and 100,000 hospital admissions every year in the U.S., according to a study in March 2022. Researchers found the annual national emergency department bill for complicated UTIs rose from $2.8 billion in 2016 to $3.2 billion in 2018.
“People often dismiss bladder infections as minor annoyances, but the bladder is a major gateway to a patients’ kidneys and bloodstream,” said study co-author Cindy Liu, associate professor of environmental and occupational health at George Washington University.
Scientists isolated and sequenced E. coli strains collected from raw chicken, turkey and pork from major grocery stores chains in Flagstaff, Arizona, and compared it with urine and blood samples from patients hospitalized at Flagstaff Medical Center for urinary tract infections.
After analyzing the genomes, they identified DNA in strains that adapted to food animals and determined that about 8% of E. coli urinary tract infections in the area could be linked to meat.
As the food supply chain is connected throughout the country, Price said scaling up from Flagstaff to the U.S. population suggests E. coli may cause hundreds of thousands of UTIs each year.
“The study design, along with advancements in genomic technologies, allowed us to establish the linkages between food sources and the clinical cases,” said study co-author Paul Keim, a professor of microbiology at Northern Arizona University. “The conclusions from this model situation will affect public health practices worldwide.”
Despite causing about8%of UTI cases each year, most strains of E. coli are not seriously monitored in the U.S. food supply, study authors said.
Surveillance programs look only for specific types of diarrhea-causing strains, like E. coli O157:H7, said study co-author Tim Johnson, a professor at the University of Minnesota’s College of Veterinary Medicine.
“There’s not any regulations as to how much (UTI-causing E. coli) can be on the meat and to what levels so they’re allowed to pass through the food system because they’re deemed not a risk to human health,” he said. “What this study shows is that there are certain strains that don’t cause acute human disease … but they still have the potential to cause disease later on via UTIs.”
Study authors hope the findings will encourage federal regulators to monitor other types of possibly harmful strains in the country’s food supply, like salmonella, as well as use this new method of tracking.
“There’s potential to apply this approach to more severe types of (pathogens),” Johnson said, “to find these strains before they enter the food supply and cause human outbreaks and make efforts to eliminate them in the flocks and herds of animals.”