Escherichia coli enteritis pathophysiology

Escherichia coli enteritis Microchapters
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Serge Korjian M.D., Yazan Daaboul, M.D.

Pathophysiology

• E. coli normally colonizes the human GI tract shortly following birth. However, the colonizing E.coli strains are different from the pathogenic strains.
• Pathogenic E. coli are characterized by the presence of either O antigen alone or combintion of O and H antigens.

• O antigen corresponds to the lipopolysaccaride antigen
• H antigen corresponds to the flagellar antigen

Extracellular vs. Intracellular Replication

• Only enteroinvasive E. coli (EIEC) has true replication within the host cell
• All other types of E. coli replicate outside the host cell.

Adhesion and Colonization

• Pathogenic E. coli strains contain adhesin that may form distinct fimbriae (pili) or fibrillae.
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Enterotoxic E. coli (ETEC)

• The primary site of action of ETEC is the small intestine.
• ETEC adheres to enterocytes then secretes 2 enterotoxins: heat-labile toxin (LT) and heat-stable toxin (ST).
• Both enterotoxins are responsible for the development of clinical manifestations (e.g. diarrhea).

Enterohemorrhagic E. coli (EHEC)

• The primary site of action of EHEC is the colon.
• EHEC attaches to the colonocyte and induces the elaboration of the Shiga toxin (Stx).
• The Shiga toxin is systemically absorbed and results in systemic complications

Enteroinvasive E. coli (EIEC)

• The primary site of action of EIEC is the colon.
• EIEC lyses phagosomes and migrates through the host cell and within cells (either lateral direct cell-to-cell spread or exit then re-enter) via the action of nucleating actin microfilaments.

Enteroaggregative E. coli (EAEC)

• The primary site of action of EAEC is the small intestine and the colon.
• EAEC adheres to enterocytes and colonocytes in a thick biofilm.
• EAEC elaborates cytotoxins and enterotoxins, such as ShET1, Pic, EAST1, Pet toxins.

Enteropathogenic E. coli (EPEC)

• The primary site of acction of EPEC is the small intestine.
• EPEC adheres to enterocytes and destroy the normal architecture of the human microvilli, resulting in cytoskeletal deformities.