Diarrheal syndromes – E. coli pathotypes and dysentery Which Escherichia coli pathotype is classically associated with an invasive process that can produce dysentery (blood and mucus in stool) rather than purely secretory watery diarrhea?

Introduction / Context:
Different pathotypes of E. coli cause distinct clinical syndromes based on their virulence mechanisms. Distinguishing invasive from toxigenic disease guides clinical suspicion and outbreak investigation.

Given Data / Assumptions:

• Dysentery implies mucosal invasion and inflammation with blood/mucus.
• Watery diarrhea is typically secretory or adherence-mediated without deep invasion.
• Multiple E. coli pathotypes are recognized.

Concept / Approach:
EIEC invades and destroys colonic epithelial cells in a manner similar to Shigella, leading to inflammatory colitis and dysentery. ETEC produces heat-labile (LT) and/or heat-stable (ST) enterotoxins causing secretory watery diarrhea. EPEC causes attaching and effacing lesions with watery diarrhea in infants. VTEC/STEC can cause hemorrhagic colitis via Shiga toxins but without classic invasion; stool may be bloody but pathophysiology is toxin-mediated rather than invasive dysentery. EAEC leads to persistent watery diarrhea with biofilm formation.

Step-by-Step Solution:
Define dysentery = invasive inflammatory diarrhea.Map EIEC to invasion and epithelial destruction.Select EIEC as the classical dysentery-associated pathotype.

Verification / Alternative check:
Pathogenesis studies and clinical descriptions consistently align EIEC with Shigella-like invasive disease.

Why Other Options Are Wrong:

• EPEC, ETEC, EAEC: typically watery diarrhea without invasion.
• VTEC/STEC: hemorrhagic colitis due to toxins, not true invasive dysentery.

Common Pitfalls:
Equating visible blood in stool with invasion; toxin-mediated bleeding from VTEC/STEC is mechanistically different from EIEC’s invasion.

Final Answer:
Enteroinvasive E. coli (EIEC).