Adhesion Gene Profiles and Urothelial Adherence in Uropathogenic Escherichia coli: Evidence of Phenotypic Convergence

Abstract

Uropathogenic Escherichia coli (UPEC) utilise several adhesin systems to colonise the urinary tract, nevertheless, the connection between gene adhesin carriage and adherence to epithelial cells is not fully understood. Here we explored the prevalence of six adhesion related genes (auf, csg, fimA, matA, papA and sfa) in 25 clinical E. coli isolates and assessed their adhesion capacity to urothelial cells. Genotypic heterogeneity was found to be noteworthy with PCR screening showing six adhesin profiles. The presence of csg, matA and papA was observed in all of the isolates, whilst fimA, auf, and sfa showed variable expression. The most widespread profile was the one with all six genes (48%). Adherence to urothelia was determined by counting the cells of the epithelia on which the bacteria were bound. On comparison of the adherence among the genotypic profiles, there were no significant differences (P > 0.05). The isolates were stratified in the presence or absence of auf, fimA, or sfa, which also demonstrated overlapping interquartile ranges and lack of significant differences in median values of adherence. These results suggested that adherence capacity under the tested conditions cannot be predicted only by adhesin gene carriage. The preserved nature of csg, matA, and papA in all isolates could give a minimum adhesion functional attribute that fills in the variation in other adhesin genes, creating similar adherence levels among different genotypes. Altogether, the findings specify the multifacetedness of the UPEC adhesion process and indicate that regulatory and expression dynamics have a far greater impact on the phenotypic adherence than the mere presence of the genes.