A Siderophore-Encoding Plasmid Encodes High-Level Virulence in Escherichia coli

Area of Science:

• Microbiology
• Genetics
• Public Health

Background:

• Hypervirulent Klebsiella pneumoniae (HvKP) poses a significant clinical threat due to acquisition of virulence plasmids.
• The role of such plasmids in other Enterobacteriaceae, like Escherichia coli, remains unclear.

Purpose of the Study:

• To investigate the virulence contribution of a novel plasmid, p1108-IncFIB, identified in a foodborne E. coli strain.
• To compare the virulence of E. coli strains with and without p1108-IncFIB, and with a Klebsiella pneumoniae virulence plasmid.

Main Methods:

• Plasmid curing and conjugation experiments were performed using E. coli and K. pneumoniae strains.
• Virulence was assessed through serum and macrophage resistance assays, and animal infection models.
• Genetic analysis included plasmid characterization and detection of carbapenemase genes.

Main Results:

• The identified plasmid p1108-IncFIB conferred high virulence to E. coli.
• A K. pneumoniae virulence plasmid, when transferred to E. coli, resulted in fitness costs and did not enhance virulence.
• The p1108-IncFIB plasmid shares siderophore genes with known virulence plasmids and is widespread in clinical E. coli.

Conclusions:

• The p1108-IncFIB plasmid significantly contributes to E. coli virulence, presenting a potential public health concern.
• Unlike K. pneumoniae, the transferred K. pneumoniae virulence plasmid did not increase E. coli virulence and incurred fitness costs.
• The prevalence of p1108-IncFIB-like virulence factors in clinical E. coli warrants further research into their impact on infections.