Genetic and Virulence Characteristics of a Hybrid Atypical Enteropathogenic and Uropathogenic Escherichia coli (aEPEC/UPEC) Strain.

Fernanda F. Santos,Tânia A. T. Gomes,Eneas Carvalho,Rita Sinigaglia,Júllia A. S. Nascimento,Ana C. M. Santos,Tiago B. Valiatti,Rosa M. Silva

doi:10.3389/fcimb.2020.00492

Abstract

Hybrid strains of Escherichia coli combine virulence traits of diarrheagenic (DEC) and extraintestinal pathogenic E. coli (ExPEC), but it is poorly understood whether these combined features improve the virulence potential of such strains. We have previously identified a uropathogenic E. coli (UPEC) strain (UPEC 252) harboring the eae gene that encodes the adhesin intimin and is located in the locus of enterocyte effacement (LEE) pathogenicity island. The LEE-encoded proteins allow enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) to form attaching and effacing (A/E) lesions in enterocytes. We sought to characterize UPEC 252 through whole-genome sequencing and phenotypic virulence assays. Genome analysis unveiled that this strain harbors a complete LEE region, with more than 97% of identity comparing to E2348/69 (EPEC) and O157:H7 Sakai (EHEC) prototype strains, which was functional, since UPEC 252 expressed the LEE-encoded proteins EspB and intimin and induced actin accumulation foci in HeLa cells. Phylogenetic analysis performed comparing 1,000 single-copy shared genes clustered UPEC 252 with atypical EPEC strains that belong to the sequence type 10, phylogroup A. Additionally, UPEC 252 was resistant to the bactericidal power of human serum and colonized cells of the urinary (T24 and HEK293-T) and intestinal (Caco-2 and LS174T) tracts. Our findings suggest that UPEC 252 is an atypical EPEC strain that emerges as a hybrid strain (aEPEC/UPEC), which could colonize new niches and potentially cause intestinal and extraintestinal infections.

Highlights

Urinary tract infection (UTI) is one of the most prevalent diseases worldwide, affecting both community and hospitalized subjects, resulting in impairment of the patients’ life quality (Terpstra and Geerlings, 2016; Wurpel et al, 2016)
uropathogenic E. coli (UPEC) strains belong to a group of E. coli clones that are collectively referred to as extraintestinal pathogenic E. coli (ExPEC), which are adapted to colonize and cause disease in different extraintestinal host sites (Russo and Johnson, 2000)
In addition to the UPEC isolates bearing enteroaggregative E. coli (EAEC) virulence genes, in the referred study, we identified a UPEC strain (UPEC 252) carrying the eae gene (Abe et al, 2008), which encodes intimin, an outer membrane adhesive protein that is fundamental for the intimate adhesion of enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) strains to intestinal cells and subsequent formation of attaching/effacing (A/E) lesions (Kaper et al, 2004)

Summary

Introduction

Urinary tract infection (UTI) is one of the most prevalent diseases worldwide, affecting both community and hospitalized subjects, resulting in impairment of the patients’ life quality (Terpstra and Geerlings, 2016; Wurpel et al, 2016). Several factors, such as surgical manipulation, diabetes, previous hospitalizations, and catheterization, are related to a Characterization of a Hybrid aEPEC/UPEC Strain higher risk for developing this disease (Saltoglu et al, 2015; Redder et al, 2016). More than 50 virulence factors have their role in ExPEC pathogenicity established (Johnson and Russo, 2018), but the ability of ExPEC to colonize a variety of host sites varies among strains reflecting their genetic diversity

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