Lipopolysaccharide core type diversity in the Escherichia coli species in association with phylogeny, virulence gene repertoire and distribution of type VI secretion systems

Abstract

Escherichia coli is a very versatile species for which diversity has been explored from various perspectives highlighting, for example, phylogenetic groupings and pathovars, as well as a wide range of O serotypes. The highly variable O-antigen, the most external part of the lipopolysaccharide (LPS) component of the outer membrane of E. coli , is linked to the innermost lipid A through the core region of LPS of which five different structures, denominated K-12, R1, R2, R3 and R4, have been characterized so far. The aim of the present study was to analyse the prevalence of these LPS core types in the E. coli species and explore their distribution in the different E. coli phylogenetic groups and in relationship with the virulence gene repertoire. Results indicated an uneven distribution of core types between the different phylogroups, with phylogroup A strains being the most diverse in terms of LPS core types, while phylogroups B1, D and E strains were dominated by the R3 type, and phylogroups B2 and C strains were dominated by the R1 type. Strains carrying the LEE virulence operon were mostly of the R3 type whatever the phylogroup while, within phylogroup B2, strains carrying a K-12 core all belonged to the complex STc131, one of the major clones of extraintestinal pathogenic E. coli (ExPEC) strains. The origin of this uneven distribution is discussed but remains to be fully explained, as well as the consequences of carrying a specific core type on the wider aspects of bacterial phenotype.

Synergy between Group 2 capsules and lipopolysaccharide underpins serum resistance in Extra-intestinal Pathogenic Escherichia coli

“…Interestingly, different core types are correlated with distinct pathotypes, as is also seen with certain O types (i.e. O25 association with extra-intestinal infections) (18). Shiga-toxin producing E. coli isolates are predominantly of the R3 core type, whilst many non-pathogenic, commensal isolates are of the K-12 core type (16).…”

Characterization and genomic study of EJP2, a novel jumbo phage targeting antimicrobial resistant Escherichia coli

“…Sequence relationships were inferred using the neighbor-joining method and evolutionary distances were computed using pdistance method by MegaX software. is diverse among different phylogroups (Leclercq et al, 2021). Because of these differences in LPS structure, the sensitivity against EJP2 was different among E. coli strains (Figure 2).…”

Identification of novel genes involved in the biofilm formation process of Avian Pathogenic Escherichia coli (APEC)

“…APEC O18 and E. coli W3110 have different LPS core structures, classified as R1 and K-12, respectively. Research regarding the relationship between LPS core type and E. coli pathogenicity is limited; however, there may be a correlation between ExPEC and LPS core type based upon phylogenetic group and virulence genes [59][60][61]. According to these data and considering the significant difference in prevalence of rfaY AO18 and rfaI AO18 among the APEC (65% and 78%, respectively) and AFEC (14% and 31%, respectively) isolates analyzed by conventional PCR, the variations of rfaY and rfaI found in APEC O18 may be specialized for ExPEC.…”