E. coli urinary infection: from the intestinal microbiota to the bladder

Actu GP infection urinaire

Does Escherichia coli need to adapt when it passes from its intestinal reservoir to the bladder in order to cause a urinary infection? Danish researchers raised the question.


Urinary infections are very frequent, affecting one in three women at the age of 24. The Escherichia coli bacteria is implicated in 80% of cases. It generally comes from the patient’s own intestinal microbiota, which suggests that it travels to the bladder via the perineum and urethra. But what does it do to adapt to the new environment? Does it have specific genetic characteristics that make colonization possible, or does it have to mutate to start the onset of symptoms? To find out, researchers analyzed the E. coli genome from urine and stool samples taken from around fifty women with urinary infections. The results showed that the 42 bacterial strains of E. coli identified in the urine were identical to the fecal strains of E. coli, except for a handful of rare genetic mutations. The authors conclude that E. coli is able to travel from the gut to the urinary bladder without needing any particular adaptation. However, it does seem to require a favorable environment in order to colonize the urinary tract.


Nielsen et al. Adaptation of Escherichia coli traversing from the faecal environment to the urinary tract.International Journal of Medical Microbiology, 306(2016)595-603