WASHINGTON – A research team claims to have found evidence that one strain of E. coli may be passed to humans via poultry meat.
Researchers with the Antibiotic Resistance Action Center (ARAC) at George Washington Univ.’s Milken Institute of Public Health, led by Lance B. Price, Ph.D., director of ARAC, and the Translational Genomics Research Institute (TGen), published their findings Aug. 28 in the American Society for Microbiology’s journal mBio.
While E. coli isn’t usually associated with urinary tract infections (UTIs), more than 80 percent of UTIs are caused by E. coli, according to ARAC. Only a few strains cause invasive UTIs that attack the kidneys or enter the bloodstream and cause life-threatening illness. E. coli ST131 is known to pass from the bladder to blood cells, and it has caused serious urinary tract infections in people worldwide. But how people contract the pathogen is clearly understood, and earlier studies ruled out meat as a source.
But Price and his colleagues discovered there are multiple strains of E. coli ST131, and one strain in particular, ST131-H22, may be passed to people through poultry meat sold at retail, according to the study.
In a statement to MEAT+POULTRY, Tom Super, senior vice president of communications for the National Chicken Council (NCC) said, “While we are taking a deeper dive into this paper, after first read it appears that Mr. Price is playing pretty loosely with the data to reach some of these conclusions. Even if you take the results at face value, about 99.8 - 99.9 percent of the strains causing UTIs were not linked to poultry.
“Those antibiotics commonly used to treat UTIs are still effective.
“Raw chicken is not sterile — we’re working every day to get as close to that as possible. But regardless of strain or resistance profile, all bacteria are properly killed and mitigated when the raw product is properly handled and cooked, and that includes avoiding cross-contamination,” said Super.
Researchers conducted a one-year study of 2,452 samples of retail chicken, turkey and pork purchased from every major grocery chain in Flagstaff, Arizona. During the same period, the team also collected 1,735 urine and blood isolates taken from patients of Flagstaff Medical Center.
The team found E. coli in 79.8 percent of the 2,452 meat samples and 72.4 percent of the urine and blood cultures taken from patients, according to the study.
Next, the researchers analyzed the genomes of the E. coli cells to determine if the E. coli detected in the meat was related to E. coli found in the urine and blood samples and whether case patients had acquired the E. coli from poultry.
Analyses revealed 27 meat isolates were ST131 and 25 belonged exclusively to the ST131-H22 lineage. Additionally, all but one of the 25 H22 meat isolates were from poultry, and all but two (23) carried poultry-associated genomes. So, the same “poultry-adapted” strain was also found to be causing urinary tract infections in people.
“Our results suggest that one ST131 sublineage — ST131-H22 — has become established in poultry populations around the world and that meat may serve as a vehicle for human exposure and infection,” the researchers wrote.
“Although previous studies suggested that food is not an important reservoir of E. coli ST131,” the researchers wrote, “these studies focused on the better-known ST131-H30 lineage, and so those findings may not accurately represent the epidemiology of other ST131 lineages, including ST131-H22.”
Price said, “In the past, we could say that E. coli from people and poultry were related to one another, but with this study, we can more confidently say that the E. coli went from poultry to people and not vice-versa.” Price added that the findings emphasize the importance of proper handling and cooking of raw poultry in home kitchens.
Researchers also noted limitations of their study. They didn’t collect data on the shopping and consumption habits of the patients in Flagstaff, so researchers could not search for correlations between the strains found in particular meat brands versus from the individuals who purchased those brands
Also, the analyses of ST131-H22 isolates outside Flagstaff were based on publicly available genome sequences that were not systematically collected. So, researchers couldn’t use them to search for host origins of the pathogens.
Finally, the researchers said their study “...was insufficient to determine definitively whether individual infections arose from direct exposure to contaminated poultry or from human-to-human transmission following the exposure to contaminated poultry.”
Price said the next step in the team’s research involves measuring what proportion of urinary tract infections might be caused by foodborne E. coli by examining all E. coli strains. “This is not an easy question to answer,” he said, “but an extremely important one.”
The United States Army Medical Research and Materiel Command; the National Institute of Allergy and Infectious Diseases at the National Institutes of Health; and the Office of Research and Development at Medical Research Service, Dept. of Veterans Affairs funded the study, Escherichia coli ST131-H22 as a Foodborne Uropathogen.