E. coli as an all-rounder: the thin line between commensalism and pathogenicity

Area of Science:

• Microbiology
• Bacterial Genetics
• Evolutionary Biology

Background:

• Escherichia coli (E. coli) is a highly adaptable bacterium with diverse strains, ranging from harmless commensals to dangerous pathogens causing intestinal and extraintestinal diseases.
• Its genomic plasticity, driven by horizontal gene transfer and mutations, fuels its variability, complicating strain identification and risk assessment.
• Distinguishing between pathogenic and commensal E. coli is challenging, especially for extraintestinal pathogens that can be part of the normal human flora.

Purpose of the Study:

• To compare the phylogenetic, genomic, and phenotypic traits of commensal and pathogenic E. coli strains.
• To investigate the blurred line between intestinal fitness and extraintestinal virulence in E. coli.
• To enhance understanding of E. coli evolution and adaptation for improved risk assessment and strain typing.

Main Methods:

• Comparative analysis of genomic content and phenotypic traits across different E. coli strains.
• Phylogenetic analysis to understand evolutionary relationships.
• Literature review and synthesis of existing data on E. coli virulence factors and adaptation.

Main Results:

• E. coli's genome plasticity allows for rapid adaptation to various niches.
• Specific genetic elements and traits are associated with intestinal or extraintestinal pathogenicity.
• A clear distinction between extraintestinal pathogenic E. coli and commensals is difficult due to facultative pathogenic nature.

Conclusions:

• Adaptability and competitiveness can enhance both intestinal colonization and extraintestinal infection by E. coli.
• The evolutionary potential of E. coli blurs the lines between commensalism and pathogenicity.
• Further research is needed to refine methods for differentiating pathogenic and commensal E. coli strains.