[Pathogenesis of urinary tract infections].

"Uropathogenic Escherichia coli" has been the term used to describe E. coli strains able to cause urinary tract infections. Their molecular characterization has demonstrated that these strains are the same as those causing infections in non-urinary extraintestinal locations, and it has been proposed thus the more inclusive term "extraintestinal pathogenic E. coli" or "ExPEC" to use. ExPEC derive mainly from the phylogenetic B2 group and harbor genes that codify virulence, such as fimH, papA, papG allele II, kspM II, hlyA, cnf1, fyuA, iutA, and traT, which are grouped in pathogenicity islands (PAIs). The vaginal ecosystem and especially Lactobacillus, as well as intestinal populations of E. coli, coitus and the physiological and anatomical conditions of the urinary tract also play a major role in the pathogenesis of urinary tract infections. The persistence of E. coli in bladder "biofilms" or "pods" or in the fecal reservoir could explain recurrent infections in young women.