.png){kind=icon}
.png){kind=icon}
Return
Genome on the move: emergence of hybrid atypical enteropathogenic/enteroaggregative Escherichia coli (aEPEC/EAEC) during a diarrheal outbreak in Brazil
.png){kind=icon}
PRE
AI
F
O
G
E
C
DOI：10.1128/spectrum.02774-25.png)
.png){kind=icon}
Original request for help.png){kind=icon}
Share.png){kind=icon}
Save
Abstract
En 中文
The plasticity of the Escherichia coli genome has allowed the emergence of pathogenic strains with unexpected genetic profiles. During an investigation of a diarrheal outbreak in Brazil, we identified one atypical enteropathogenic (aEPEC), four enteroaggregative (EAEC), and three hybrid aEPEC/EAEC E. coli strains, all belonging to the serotype O3:H2. Short-read sequencing and long-read sequencing of these strains were performed to generate draft and complete genome assemblies, which were subjected to comprehensive analyses. The outbreak-associated O3:H2 strains were classified within phylogroup A, assigned to the sequence types ST10 (2 EAEC) or ST8087 (1 aEPEC, 2 EAEC, and 3 hybrid aEPEC/EAEC), and were closely related according to the phylogenetic analysis performed. The comparison of their chromosomes revealed key genetic features in the hybrid aEPEC/EAEC strain, including a prophage carrying genes encoding 3 EPEC-translocated effectors (nleB2, nleF, and nleH2) and the locus of enterocyte effacement (LEE region) subtype 8, identical to that found in the aEPEC strain. Additionally, the plasmid of aggregative adherence (pAA) identified in the EAEC and hybrid aEPEC/EAEC strains shared approximately 100% nucleotide identity across at least 85.7% of their sequences and contained the aggDCBA operon and its regulator aggR. In conclusion, our findings suggest that all E. coli strains of serotype O3:H2 belonging to the ST8087 studied likely originated from a common ancestor, which, through multiple horizontal gene transfer events, contributed to the emergence of the aEPEC and EAEC pathotypes, as well as the hybrid aEPEC/EAEC strain.IMPORTANCEThis study provides evidence that the high genomic plasticity of Escherichia coli has played a key role in the emergence of diarrheagenic strains harboring virulence markers from atypical enteropathogenic (aEPEC) and enteroaggregative (EAEC) E. coli, as well as strains with markers from both pathogenic groups, combined in hybrid aEPEC/EAEC strains. Phylogenetic analysis suggests that these strains share a common ancestral lineage within the ST10, from which a branch subsequently differentiated into the ST8087. The presence of mobile genetic elements shared among all strains, alongside others that are pathotype-specific, highlights the mosaic architecture of these genomes. Elucidating this evolutionary process, particularly the generation of E. coli strains with novel combinations of virulence genes, is essential for advancing our understanding of the evolution of the diarrheagenic E. coli (DEC) genome and its implications for pathogenicity.
Keywords:
hybrid aEPEC/EAEC
diarrheal outbreak
genomic plasticity
Journal
IF:
3.8
Papers:
8.2K
Citations:
2.5W
Organization
Cited Papers