Genomic Characterization of Multidrug-Resistant Escherichia coli BH100 Sub-strains

Area of Science:

• Microbiology
• Genetics
• Genomics

Background:

• Multidrug-resistant (MDR) bacteria pose a significant global health threat.
• Mobile genetic elements (MGEs), including plasmids and transposons, are key drivers of antimicrobial resistance gene dissemination in uropathogenic Escherichia coli (UPEC).
• The transposable elements of the E. coli BH100 strain, a historical isolate, remained uncharacterized.

Purpose of the Study:

• To investigate the role of transposable elements in the mobilization of virulence and drug-resistance genes within the E. coli BH100 strain.
• To analyze genomic rearrangements and identify specific mobile genetic elements responsible for gene transfer in BH100 sub-strains.

Main Methods:

• Whole-genome sequencing of four BH100 sub-strains using Next Generation Sequencing (NGS).
• Comparative genomic analysis to identify recombination events and mobile genetic elements.
• Genomic island analysis to assess the association of MGEs with virulence and resistance genes.

Main Results:

• Recombination events were observed between plasmids and between a plasmid (pBH100) and the chromosome in specific BH100 sub-strains.
• IS3 and IS21 elements were frequently found associated with Tn21 family transposons carrying multidrug resistance genes at recombination sites.
• The pBH100 plasmid appears to contribute to the spread of drug resistance via resistance island formation.
• BH100 strain exhibits genomic islands enriched with IS3 and IS21 transposases, linked to virulence, confirming its UPEC relation.

Conclusions:

• IS3 and IS21 elements play a critical role in the evolution and adaptation of the E. coli BH100 strain.
• These insertion sequence elements facilitate the acquisition and spread of both drug resistance and virulence genes.
• The findings highlight the importance of understanding MGEs for combating the rise of MDR pathogens.