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Role of aggregate-forming pilus (AFP) in adherence and colonization of both intestinal and urinary tracts

Paulo A Schüroff1,2, Cecilia M Abe1, Jonatas W Silva1

  • 1Laboratório de Bacteriologia, Instituto Butantan, São Paulo, Brazil.

Virulence
|August 19, 2022
PubMed

Insights

Hybrid pathogenic Escherichia coli strains utilize aggregate-forming pili (AFP) and type I fimbriae (TIF) synergistically for intestinal and urinary tract colonization. These adhesins are crucial for infections in both systems.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Bacterial Pathogenesis

Background:

  • Hybrid-pathogenic *Escherichia coli* strains cause significant intestinal and extraintestinal infections.
  • Aggregate-forming pili (AFP) mediate aggregative adherence in UPEC-46, a uropathogenic/enteroaggregative *E. coli* (UPEC/EAEC) strain.
  • The precise roles of AFP and other fimbriae in UPEC-46 pathogenesis require elucidation.

Purpose of the Study:

  • To investigate the involvement of AFP and other adhesins in the uropathogenicity and intestinal colonization of *E. coli* UPEC-46.
  • To delineate the specific contributions of AFP and type I fimbriae (TIF) to adherence and invasion in relevant epithelial models.
  • To assess the in vivo significance of these adhesins in both intestinal and urinary tract infection models.

Main Methods:

  • In vitro adherence and invasion assays using intestinal and urinary epithelial cell lines.
  • Construction and analysis of transposon mutants to identify key adhesins.
  • In vivo studies utilizing streptomycin-treated mice for intestinal colonization and a murine ascending urinary tract infection model.
  • Electron microscopy (EM) for visualizing bacterial adherence structures.

Main Results:

  • UPEC-46 demonstrated adherence and invasion capabilities in both intestinal and urinary cell lines.
  • Type I fimbriae (TIF) were identified as crucial for adherence to epithelial cells, alongside AFP.
  • In vivo, both AFP and TIF enhanced bacterial counts in the colon, with AFP primarily associated with kidney colonization and TIF with bladder colonization.

Conclusions:

  • Aggregate-forming pili (AFP) and type I fimbriae (TIF) play synergistic roles in the adherence and colonization of both intestinal and urinary epithelia.
  • Hybrid *E. coli* strains possessing both AFP and TIF are likely to cause concurrent intestinal and urinary tract infections.
  • Targeting these adhesins could offer novel therapeutic strategies against hybrid *E. coli* infections.
Keywords:
AFPHybrid-pathogenicE. coliaggregate-forming pilusintestinal colonizationurinary tract infection

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