Defining the genome features ofEscherichia albertii, an emerging enteropathogen closely related toEscherichia coli

Abstract

Escherichia albertii is a recently recognized close relative of Escherichia coli. This emerging enteropathogen possesses a type III secretion system (T3SS) encoded by the locus of enterocyte effacement, similar to enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC). Shiga toxin-producing strains have also been identified. The genomic features of E. albertii, particularly differences from other Escherichia species, have not yet been well clarified. Here, we sequenced the genome of 29 E. albertii strains (3 complete and 26 draft sequences) isolated from multiple sources and performed intraspecies and intragenus genomic comparisons. The sizes of the E. albertii genomes range from 4.5 to 5.1 Mb, smaller than those of E. coli strains. Intraspecies genomic comparisons identified five phylogroups of E. albertii. Intragenus genomic comparison revealed that the possible core genome of E. albertii comprises 3,250 genes, whereas that of the genus Escherichia comprises 1,345 genes. Our analysis further revealed several unique or notable genetic features of E. albertii, including those responsible for known biochemical features and virulence factors and a possibly active second T3SS known as ETT2 (E. coli T3SS 2) that is inactivated in E. coli. Although this organism has been observed to be nonmotile in vitro, genes for flagellar biosynthesis are fully conserved; chemotaxis-related genes have been selectively deleted. Based on these results, we have developed a nested polymerase chain reaction system to directly detect E. albertii. Our data define the genomic features of E. albertii and provide a valuable basis for future studies of this important emerging enteropathogen.

Multiplex polymerase chain reaction for identification of Escherichia coli , Escherichia albertii and Escherichia fergusonii

“…Traditionally, E. albertii was detected with a multiplex PCR for the presence of clpX, lysP , and mdh genes but this does not detect all E. albertii (Hyma et al, 2005, Murakami et al, 2014, Lindsey et al, 2015). Recently, Ooka et al developed a nested PCR to detect E. albertii (Ooka et al, 2015); however, this assay does not detect additional Escherichia species. There are also rpoB gene sequencing based methods or multi locus sequencing of whole genome sequence (WGS), but these methods are time consuming and take days to complete (Hyma et al, 2005, Murakami et al, 2014, Lindsey et al, 2015).…”

Evaluation of Five Polymerase Chain Reaction (PCR) Assays for Diagnosis of the Shiga Toxin 2f-Producing <i>Escherichia coli</i>

“…Surveillance in recent years shows that stx2f-harboring strains are increasingly associated with diarrhea and sporadic HUS cases in Europe and Japan (5,6,7). In addition, it has been shown that E. albertii, which possesses major Stx2f-STEC properties, can also be considered as an emerging pathogen (8). Among the 7 known stx2 subtypes, Shiga toxin 2f detection can be challenging because most of the genotypic and phenotypic methods fail to detect this subtype (2,9,10).…”

Harnessing The Power Of Recombineering To Interrogate The Virulome Of Escherichia albertii

“…Bacteria that express stx 2a are characterized as highly virulent because they can induce the life-threatening pathology of hemolytic uremic syndrome (HUS) [17,18] . Additional virulence factors, including the presence of a second type III secretion system (ETTS) and the genes for the cytolethal-distending toxin are also encoded in the genome of E. albertii [19] . This impressive array of virulence factors appears to be but the tip of the iceberg, since the mining of its pangenome has only just begun [19] .…”

“…Additional virulence factors, including the presence of a second type III secretion system (ETTS) and the genes for the cytolethal-distending toxin are also encoded in the genome of E. albertii [19] . This impressive array of virulence factors appears to be but the tip of the iceberg, since the mining of its pangenome has only just begun [19] . Given the diversity of its virulence factors it comes as no surprise that E. albertii has been implicated as the etiologic agent for multiple outbreaks of gastroenteritis in both developing and developed nations [20][21][22] .…”

“…This limitation stems from the lack of a suitable molecular technique for targeted mutagenesis in the bacterium. As a consequence, the number and nature of virulence factors in E. albertii has merely been predicted by biocomputational approaches and correlation-based expression studies [19] . However, the litmus test, namely the construction of mutants and observation of pathophenotypic perturbations in the mutant with respect to the unaltered parent, has yet to be conducted.…”