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Genetic diversity and virulence characteristics of biofilm-producing uropathogenic Escherichia coli


Uropathogenic E. coli (UPEC) strains exhibit different levels of biofilm formation that help adhesion of the bacteria to uroepithelial cells. We investigated the genetic diversity and virulence-associated genes (VAGs) of biofilm-producing UPEC. A collection of 107 biofilm-producing (BFP) UPEC strains isolated from patients with UTI in Iran were divided into three groups of strong, moderate, and weak BFPs after a quantitative microtiter plate assay, and the involvement of curli and cellulose in adhesion of the strains to T24 cell line was confirmed by the construction of csgD and yedQ mutants of two representative UPEC strains. BFP strains were tested for their genetic diversity, phylogenetic groups, and the presence of 15 VAGs. A significant decrease in adhesion of csgD and yedQ mutant strains confirmed the role of biofilm production in adhesion to uroepithelial cells. A high diversity was found among all three groups of strong (Di = 0.998), moderate (Di = 0.998), and weak (Di = 0.988) BFPs with majority of the strains belonging to phylogroups B2 (44.9%) and A (24.3%). Strong BFP strains carried significantly higher level papEF, hlyA, and iutA than other BFP groups. In contrast, the presence of fimH, focG, sfaS, set-1, and cvaC was more pronounced among weak BFP strains. There exists a high genetic diversity among the BFP strains with different VGA profiles. However, the high prevalence of phylogroup A among BFP strains suggests the fitness of commensal E. coli strains to cause UTI in this country.

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The datasets used during the current study are available from the corresponding author upon request.

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The results presented in this paper were part of Mr. Ali Qasemi’s Ph.D thesis supported by a grant from the Office of Vice-Chancellor for Research and Technology, University of Isfahan, Isfahan, Iran, and also Iran National Science Foundation, Tehran, Iran.

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All authors have contributed equally to the manuscript.

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Correspondence to Fateh Rahimi.

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Ethical approval was not required for this article since clinical isolates were collected from hospitals and none of the authors have worked directly with human samples.

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Qasemi, A., Rahimi, F. & Katouli, M. Genetic diversity and virulence characteristics of biofilm-producing uropathogenic Escherichia coli. Int Microbiol 25, 297–307 (2022).

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  • UTI
  • UPEC
  • Biofilm
  • Virulence factors
  • Phylogenetic groups