Each year, between 4 million and 6 million people in the United States have urinary tract infections caused by E. coli. About half a million of those — between 480,000 and 640,000 — could be linked to strains known as foodborne zoonotic E. coli, a new study suggests.
“We’re used to the idea that foodborne E. coli can cause outbreaks of diarrhea, but the concept of foodborne E. coli causing urinary tract infections seems strange — that is, until you recognize that raw meat is often riddled with the E. coli strains that cause these infections,” Lance Price, one of the study’s authors and a professor specialising in antibiotic resistance at the George Washington University’s Milken Institute School of Public Health in Washington D.C. “Our study provides compelling evidence that dangerous E. coli strains are making their way from food animals to people through the food supply and making people sick — sometimes really sick.”
Although the idea that foodborne E. coli strains could cause UTIs was introduced in the 1960s, the scientific community lacked the fundamental understanding of where these strains originated and how they were transmitted.
“Our question was: how did the E coli that caused the UTI get into the gut in the first place?” Price said.
For their study, the researchers collected samples of chicken, turkey and pork from the main grocery stores in Flagstaff, Arizona, every couple of weeks throughout 2012. At the same time, they took blood and urine samples from people in that area who were hospitalized with a UTI.
“Flagstaff was the perfect place,” Price said. “We could go to the shops, buy the meat and then go to the local hospital and get all the UTI E coli samples and compare them.” The study used 1,188 human clinical urine and blood isolates taken at the hospital.
“At the end of the year we sequenced the E coli we’d collected, and because I learned that E coli adapt to different hosts — people, chickens, whatever — by pulling in packets of DNA, we could look at the DNA packets and work out their statistical relation to each host … (and then) we could estimate the proportion of UTI E. coli coming from food animals.”
The researchers determined 8% of Flagstaff’s UTIs were caused by E. coli from the area’s meat samples. Scaling those numbers nationwide comes to between 480,000 and 640,000 cases each year.
Why does this matter?
Most people think of UTIs as a temporary discomfort, “but the bladder is a major gateway to patients’ kidneys and bloodstream,” said Cindy Liu, co-author of the study. “People over 55 and vulnerable populations such as cancer and transplant patients are at the highest risk for life-threatening blood infections, but young, healthy people are also at risk.”
E. coli bloodstream infections kill 36,000-40,000 people in the U.S. every year. Price warned that as E. coli — already resistant to some antibiotic treatments — becomes resistant to even more antibiotics, the number of people dying from bloodstream infections could rise. Reducing UTIs caused by meatborne E. coli strains would help reduce those deaths, he said.
The researchers suggest meat producers and the Food and Drug Administration do a better job of monitoring pathogens in raw meat sold in U.S. grocery stores. They also warn consumers to take precautions when preparing raw meat — washing hands carefully and preparing raw meat on a surface separate from other foods.
The study was published online Thursday in the journal One Health.
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