Genetic Diversity and Virulence Determinants of Escherichia coli Strains Isolated from Patients with Crohn's Disease in Spain and Chile

Abstract

Adherent-invasive Escherichia coli (AIEC) strains are genetically variable and virulence factors for AIEC are non-specific. FimH is the most studied pathogenicity-related protein, and there have been few studies on other proteins, such as Serine Protease Autotransporters of Enterobacteriacea (SPATEs). The goal of this study is to characterize E. coli strains isolated from patients with Crohn's disease (CD) in Chile and Spain, and identify genetic differences between strains associated with virulence markers and clonality. We characterized virulence factors and genetic variability by pulse field electrophoresis (PFGE) in 50 E. coli strains isolated from Chilean and Spanish patients with CD, and also determined which of these strains presented an AIEC phenotype. Twenty-six E. coli strains from control patients were also included. PFGE patterns were heterogeneous and we also observed a highly diverse profile of virulence genes among all E. coli strains obtained from patients with CD, including those strains defined as AIEC. Two iron transporter genes chuA, and irp2, were detected in various combinations in 68–84% of CD strains. We found that the most significant individual E. coli genetic marker associated with CD E. coli strains was chuA. In addition, patho-adaptative fimH mutations were absent in some of the highly adherent and invasive strains. The fimH adhesin, the iron transporter irp2, and Class-2 SPATEs did not show a significant association with CD strains. The V27A fimH mutation was detected in the most CD strains. This study highlights the genetic variability of E. coli CD strains from two distinct geographic origins, most of them affiliated with the B2 or D E. coli phylogroups and also reveals that nearly 40% of Chilean and Spanish CD patients are colonized with E.coli with a characteristic AIEC phenotype.

Comparative genomics reveals new single-nucleotide polymorphisms that can assist in identification of adherent-invasive Escherichia coli

“…Our analysis revealed no association between the presence of previously AIEC-associated genes ( lpfA 154 , gipA , pduC , fyuA , afaC , chuA and ibeA ) 15 – 17 , 20 , 21 , 37 , 38 and the AIEC phenotype, in concordance with previous observations 17 , 27 . A similar situation was found with respect to the genetic variants of fimH , ompA and chiA .…”

Molecular Characteristics of ST1193 Clone among Phylogenetic Group B2 Non-ST131 Fluoroquinolone-Resistant Escherichia coli

“…Escherichia coli ( E. coli ) is commonly found in the gut flora of humans and can cause many different kinds of extra-intestinal infections, such as septicemias, meningitis and urinary tract infections ( Pitout, 2012 ; Poolman and Wacker, 2016 ). Many methods can be used for typing E. coli , including serotyping, pulsed-field gel electrophoresis (PFGE) and various PCR-based molecular methods( Jonas et al, 2003 ; Cespedes et al, 2017 ; Roer et al, 2017 ). Multilocus sequence typing (MLST) is a PCR-based molecular typing method and is considered the “gold standard” subtyping technique that can usually be used to detect the genetic relatedness between strains and identify a specific clone with high discriminatory ability for various bacterial pathogens ( Maiden et al, 2013 ; Perez-Losada et al, 2013 ).…”

The Crohn’s disease-related AIEC strain LF82 assembles a biofilm-like matrix to protect intracellular microcolonies from phagolysosomal attack

“…An analysis of the genetic diversity of E. coli isolated from patients with Crohn's disease revealed that 25 out of 32 strains (78%) encode the irp2 gene and presumably the rest of the HPI cluster in their genome. Among these 32 strains, only 13 presented an AIEC phenotype, and the prevalence of irp2 in this group was 70% (Céspedes et al, 2017). In contrast, this association was only 30% for the control group.…”

“…The diversity of virulence factors displayed by multiple AIEC strains suggests that members of this pathovar may have evolved different strategies to colonize their hosts (Tawfik et al, 2014). However, virulence factors involved in iron capture (the high-pathogenicity island (HPI), chuABCD, fhuD or sitABCD system) exhibit a high prevalence among AIEC strains (Céspedes et al, 2017), suggesting that iron capture is a crucial determinant for AIEC strains to form their ecological niches.…”