The Dual Role of Escherichia coli: Transitioning from a Commensal Organism to a Pathogen in Urinary Tract Infections

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Escherichia coli is a minor but consistent member of the human gut microbiota, contributing to colonization resistance and immune tolerance.
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E. coli can transition from a beneficial gut commensal to a harmful pathogen when it enters the urinary tract, leading to urinary tract infections.
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Pathogenic E. coli strains are categorized into intestinal pathogenic E. coli (InPEC) and extraintestinal pathogenic E. coli (ExPEC) based on infection site.
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Uropathogenic E. coli (UPEC) is a major cause of urinary tract infections, utilizing specific adhesins and iron-acquisition systems for colonization.
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The transition from commensal to pathogen in E. coli is influenced by environmental signals such as urine osmolarity and iron limitation.

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