**4. Conclusions and the way forward**

The heterogeneous nature of strains could be because of the HGT through mobile genetic elements. The genetic exchanges that occur in bacteria provide genetic diversity and versatil‐ ity. Plasmids, bacteriophages, and genomic islands belong to the flexible *E. coli* genome and their genetic information can be horizontally acquired. The rapid evolution of *E. coli* vari‐ ants contributes to these genomic regions as they are subject to rearrangements, excision, and transfer frequently. The creation of new pathogenic variants is the result of further acquisition of additional genome.

The accumulating amount of sequence information generated in the era of "genomics" helps to increase our understanding of factors and mechanisms that are involved in diversifica‐ tion of this new bacterial species, as well as in those that may direct host-specificity. From a comparative genomic aspect, a significant challenge is to utilize bulky amount of datasets to distinguish and conceptualize specific sequence signatures that scientifically or diagnostically are applicable traits. By comparing more sequence data from different strains, new signature biomarkers will be recognized for use as vaccines or as diagnostic factors in future. Signature conserved proteins in a wide range of pathogenic bacterial strains can potentially be used in modern vaccine-design strategies.
