New Study Links Urinary Tract Infections to Animal-Origin E. Coli

Recent research indicates that around 20% of urinary tract infections (UTIs) in Southern California may stem from Escherichia coli strains found in food-producing animals.

A team from George Washington University and Kaiser Permanente Southern California (KPSC) examined over 5,700 extraintestinal pathogenic E. coli (ExPEC) samples taken from UTI patients and retail meat products in their communities. Using advanced genomic analysis, they determined that 18% of the UTIs were associated with ExPEC strains originating from meat.

Interestingly, patients living in high-poverty neighborhoods were 60% more likely to experience UTIs caused by these animal-derived ExPEC strains.

The findings were released recently in the journal mBio.

The authors emphasized the role of zoonotic ExPEC in the UTI epidemic and highlighted the necessity for targeted actions to lessen risks in at-risk communities.

Underrecognized Source of UTIs

This research builds upon over a decade of studies by Lance Price, PhD, who heads the Antibiotic Resistance Action Center at George Washington University.

In a 2018 study, Price’s team noted a strain of E. coli linked to severe UTIs worldwide was prevalent in chicken and turkey meat. A follow-up study earlier this year found that 8% of E. coli samples from human UTIs in Flagstaff, Arizona, were connected to meat sold in local grocery stores.

Price expressed surprise at the higher percentage in recent results, saying it prompted further investigation.

Typically, foodborne E. coli is associated with gastrointestinal issues, especially strains like Shiga toxin-producing E. coli. These strains are monitored by health authorities to prevent food contamination. However, Price and his colleagues argue that foodborne ExPEC strains contributing to UTIs are often overlooked.

“The strains that cause the most fatalities are the extraintestinal pathogenic E. coli, which can exist in the gut without symptoms,” he pointed out. “If they enter the urinary tract, they have specific characteristics that allow them to cause disease.”

Zoonotic E. Coli’s Role in UTIs

The research team, which included scientists from several prominent institutions, conducted whole-genome sequencing on 2,349 clinical E. coli samples from KPSC labs collected between February 2017 and May 2021. The demographics reflected a predominantly Hispanic (37%) and non-Hispanic White (31.7%) patient base in various poverty settings.

They also sequenced samples from 3,379 retail meat products, testing chicken, turkey, beef, and pork. Turkey samples had the highest contamination rate (82%), followed by chicken (58%), pork (54%), and beef (47%). Stores in lower-income neighborhoods had higher contamination levels.

The researchers compared the genomes of human and foodborne E. coli samples, looking for specific genetic elements linked to animals. This helped them trace the origins of the bacteria.

According to their estimations, approximately 17.7% of the human E. coli isolates originated from food-producing animals, mostly chickens and turkeys. Additionally, the study indicated that certain poultry-related E. coli strains appeared to be more adept at causing UTIs, with urine samples from women being notably more susceptible than those from men (19.7% vs. 8.5%).

Antibiotic Resistance

Interestingly, the zoonotic ExPEC strains were found to be less resistant to common antibiotics used for treating UTIs compared to non-zoonotic strains.

This observation may suggest that the FDA’s efforts to regulate antibiotic use in livestock are yielding positive results. Despite ongoing critiques regarding their approach, studies indicate that in countries with lax livestock antibiotic regulations, there are much higher resistance rates in bacteria transmitted from animals to humans.

Gail Hansen, DVM, a public health and veterinary consultant who didn’t participate in the study, noted that this link between UTIs and E. coli from animals underscores the importance of antibiotic stewardship. “We can’t afford to misuse antibiotics anywhere,” she added.

Poverty and Zoonotic E. Coli Connection

Notably, the highest percentage of zoonotic ExPEC strains (21.5%) was found in patients from high-poverty areas. After accounting for factors like age, gender, and race/ethnicity, those in high-poverty neighborhoods showed a 1.6-fold increase in risk of zoonotic ExPEC infections compared to those in lower-poverty settings.

The reasons behind this correlation remain unclear and warrant more research. Price mentioned that when he first investigated this issue, he noticed that chicken from poorer areas tended to be poorly packaged, potentially harboring bacteria from leakage.

Although this study didn’t focus on meat packaging, he speculated that it might be a relevant factor. “It seems possible that the lowest-quality meat in poor packaging is sold in areas with less economic means,” he said, suggesting further examination is worth pursuing.

Recognizing meat as a potential exposure source for zoonotic E. coli could be crucial in tackling UTI prevalence. One option is for regulatory bodies to test for various E. coli types beyond just those known for gastrointestinal diseases.

“Most chicken or turkey I test contains E. coli,” he noted, advocating for more efforts to reduce contamination.

In the meantime, he advised consumers to maintain safe food-handling practices, including cooking meat thoroughly and washing hands and surfaces to avoid cross-contamination.

“Assume you’ve introduced bacteria into your kitchen when you open that package. Treat every piece of meat as potentially contaminated,” he advised.