Cystitis is a universal burden. Worldwide, one in two women contracts at least one urinary tract infection in her lifetime. In France, every year, one in ten women suffers the inconveniences. They are caused by the migration of a pathogenic strain of the bacterium Escherichia coli (E. coli), naturally present in the intestinal microbiota. But beyond the mild form which is confined to the bladder, cystitis can degenerate into a more severe, even fatal, infection which “colonizes” the kidneys and the general blood system.
It is on these serious infections, “likely to increase in the population”, that Toulouse researchers from Digestive Health Research Institute (IRSD)* attract attention. In a article published this summer in the journal Clinical Microbiology and Infection (CMI), they identify “an emerging clone” – “more evil”, popularizes Professor Eric Oswald, biologist at the Toulouse University Hospital – of the bacterium E. coli as being at the origin of the most severe cystitis.
Be more vigilant with fragile patients
To achieve this result, the team isolated and characterized strains of E. coli from the “urine cultures” of 223 patients who went through the emergency department of the Toulouse University Hospital for urinary tract infections. They identified “a virulence factor carried by a plasmid – a small piece of DNA that can jump from bacterium to bacterium”, explains the specialist. This virulence factor was found in 20% of patients in the cohort. To find out for sure, and not get the wrong culprit, “mutated” bacteria without this famous plasmid and the gene coding for this virulence factor were inoculated into mice. None developed a severe urinary tract infection.
The Toulouse study shows that it is necessary “perhaps to be more attentive to an infection that we have perhaps a little too trivialized”. The idea is not to look for the famous emerging clone each time cystitis occurs. “But, in certain cases, in patients who are more fragile, such as older women, or patients with comorbidities, we must certainly go further in the analyzes and characterization of the strains”, underlines Eric Oswald. This way, the right antibiotic treatment could be administered sooner.
* Inserm/INRAE/ENVT/Toulouse 3 University