Researchers at McGill University in Montreal have found new evidence that eating Escherichia coli-contaminated chicken can cause urinary tract infections (UTIs).
These results raise important public health issues, primary author Amee Manges, PhD, MPH, told Food Quality. The first issue is “that E. coli transferred in food—which we usually think of as causing diarrhea—may actually be responsible for many UTIs and other infections outside the gut. [The second issue is] that these E. coli may be resistant to antibiotics, due to use in food animal production.” Dr. Manges is an assistant professor in the department of Epidemiology, Biostatistics, and Occupational Health at McGill.
Lee W. Riley, MD, professor of epidemiology and infectious diseases, University of California, Berkeley, said this is an important study because it “clearly shows that E. coli strains found in common food can cause extra-intestinal infection, such as UTI. That is, E. coli that causes human illness is not just limited to those that cause diarrhea.”
We are working to provide even more direct evidence of a link, if one exists, that these E. coli—extraintestinal E. coli—can be transferred via food.
—Amee Manges, PhD, MPH, McGill University
Acquired From a Common Source
The researchers’ previous work revealed that some women were developing UTIs due to the same E. coli strain. “Usually you see this kind of pattern of infections with the same strain in disease outbreak settings. So we thought that maybe these women were acquiring their E. coli from a common source; the most likely candidate was food.”
Dr. Manges and colleagues collected E. coli isolates from study participants, restaurant/ready-to-eat foods, and retail chicken in the Montreal area between 2005 and 2007. They collaborated with the Public Health Agency of Canada and the University of Guelph. Their results showed that some of the E. coli found in retail chicken meat was closely related to the E. coli that causes UTIs in humans.
Eating E. coli-contaminated food does not directly cause a UTI, Dr. Manges said. “Once in the gut, the E. coli don’t cause any problems,” she said. “Then something happens to cause a UTI or other infection outside the gut. UTIs often occur in young women because they are sexually active. The mechanics of sex help move the E. coli from the gut” via the anus “to the vagina and urethra, leading to infection.”
The issue is how widespread is the UTI caused by foodborne E. coli?
—Lee W. Riley, MD, UC Berkeley
Looking for Direct Evidence
Research on this topic is ongoing. “We are working to provide even more direct evidence of a link, if one exists, that these E. coli—extraintestinal E. coli—can be transferred via food,” Dr. Manges said. “If this is the case, we will also look at markers of drug-resistance to see if resistant E.coli are also transferred.”
More research must determine the extent of this problem. “The issue is how widespread is the UTI caused by foodborne E. coli? We don’t know since studies specifically looking at this question are recently being done,” Dr. Riley told Food Quality.
The difficult task is how to apply these results to food safety. Preventing food contamination by uropathogenic E. coli at the animal reservoir or food processing sites is challenging, Dr. Riley said. “One thing the food industry can do is to avoid using antibiotics as growth promoters. If this practice is stopped, we can at least prevent drug-resistant E. coli from spreading by food.”
James R. Johnson, MD, director, Infectious Disease Fellowship Program and professor of medicine at the University of Minnesota, Minneapolis, told Food Quality that there are a few other preventive approaches, including more hygienic food processing and distribution methods, irradiating foods, washing fruits and vegetables before consumption, careful kitchen hygiene, and thoroughly cooking meats. ■