Étude des gènes de pathogénicité des souches d’Escherichia coli.

Abstract

Escherichia coli (E. coli) is the predominant species of the human gastrointestinal tract. It includes commensals as well as intestinal (InPEC) and extra-intestinal (ExPEC) pathogenic strains. ExPEC is a global public health problem. They have the characteristic of being versatile bacteria and are the cause of the vast majority of urinary tract infections, one of the main causes of bacteremia in adults and the second cause of neonatal meningitis. The worrying upsurge in antibiotic resistance among ExPEC strains, treatment failure, hospitalization, mortality, and rising health care. In this study, we identified the phylogenetic group of each strain and prospected the genetic profile linked to the virulence genes within two ExPEC groups: the first being the UPEC isolated from Algerian patients suffering from urinary tract infections. The second, that of ExPEC from Algerian patients with various extra-intestinal infections. The main objective of our research is to identify the virulence factors generally associated with different pathotypes linked to ExPEC and others normally linked to InPEC pathotypes. This selection will also make it possible to highlight any hybrid strains (ExPEC/InPEC). Our results showed that astA, hlyA and pap genes were the most predominant virulence markers among the two groups. The results obtained revealed a total absence of the stx1, stx2 and ST1 genes on all the strains studied. The most commonly encountered phylogenetic group was B2. Our study also reported a higher of phylogenetically unclassifiable strains. The results also revealed diverse significant associations between studied genes and the different phylogroups as well as between E. coli from hospitalized patients with UTIs and the pap and hlyA genes (p-0.041 and p-0.019 respectively). The results obtained also revealed the presence of 14 hybrid strains. A better characterization of the ExPEC strains by the identification of the phylogenetic group and the determination of the pathogenicity of the strains will make it possible to improve their diagnoses and will provide targeted alternative therapeutic solutions. This is to try to address the increased growth of antibiotic resistance reinforced by systemic antibiotic therapy.