E. coli bacteria are very often involved in the development of urinary tract infections. For the first time, scientists have detected the presence of a toxin produced by these bacteria in the urine of patients, which is believed to damage the DNA of bladder cells. These findings pave the way for new thinking to refine the treatment of patients with recurrent urinary tract infections. The study was published in the journal PLOS Pathogens on February 25, 2021.
One in two women suffer from urinary tract infections
Each year, 150 million people are affected by urinary tract infections. They are more common in women: more than one in two will experience them during her lifetime. These infections are therefore a major public health problem, especially since treatment with antibiotics is often necessary, leading to the emergence of antibiotic resistance.
Urinary tract infections occur when the urogenital region is infected with bacteria from the gut microbiota. Escherichia coli bacteria (E. coli) are thus implicated in 80% of these infections and have been the subject of research work for several years by Eric Oswald and his team at the Digestive Health Research Institute as part of a collaboration with several research teams in Toulouse France.
The scientists were particularly interested in the virulence factors of these bacteria, i.e. their ability to infect or damage host tissues. They had already shown that E. coli can produce a toxin, colibactin, in the intestinal tract under certain conditions, which is associated with an increased risk of colorectal cancer. In this new study, the team analyzed the urine samples of 223 adults with an E. coli-related urinary tract infection who were treated in the emergency department of the University Hospital of Toulouse.
They identified a biomarker that demonstrates the presence of colibactin, produced by E. coli bacteria, in at least 25% of the urine samples collected. This is the first time this toxin has been identified in the context of urinary tract infection and researchers have provided direct evidence of its production during infection in humans.
To better understand and characterize the effects of colibactin in the context of urinary tract infections, the researchers turned to animal models. They showed that the toxin is produced in mice during urinary tract infection with E. coli and that it induces DNA damage in bladder mucosal cells.
“With these experiments, we can go beyond a very theoretical framework and show that colibactin can have a genotoxic effect during urinary tract infection,” he said. DNA damage does not fully repair itself and genetic mutations can occur. “Although at this time we can only speculate on the impact of these mutations, it is likely that they are associated with an increased risk of bladder cancer,” says Eric Oswald.
Increased surveillance for recurrent urinary tract infections
While these results from animal models cannot be applied to humans at this time, the researcher and his team believe they could nevertheless lead to more comprehensive and targeted surveillance of people with recurrent urinary tract infections.
A better understanding of the links between gut microbiota and recurrent urinary tract infections is also considered a priority. “One could envision setting up a more targeted approach to patients who have frequent urinary tract infections, with a systematic search for colibactin markers in their urine. And more proactively, propose therapeutic approaches aimed at modulating the composition of their gut microbiota, which is the main reservoir of the E. coli bacteria involved in these urinary tract infections,” concludes Eric Oswald.
Are you suffering from repetitive urinary tract infections? Do you know what bacteria are involved? Please share your story with us in the comments area below?