Question

Shigella like invasiveness is typical for ............. strain of E. coli.

• A. EPEC
• B. ETEC
• C. EIEC
• D. ECEC

Hint:

Remember the direct association:
- EIEC = Invasive pathotype that mimics Shigella dysentery.
- ETEC = Toxin-producing pathotype responsible for traveler's diarrhea.
- EPEC = Pedestal-forming pathotype causing infantile diarrhea.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Escherichia coli strains are common inhabitants of the intestinal tract, but certain pathogenic strains have acquired specific virulence factors.
These pathogenic strains are classified into distinct pathotypes based on their clinical symptoms, virulence mechanisms, and O:H serotypes.

Step 2: Detailed Explanation:
Let us analyze the pathotypes of diarrheagenic Escherichia coli:
-Enteroinvasive E. coli (EIEC):
EIEC strains are biochemically, genetically, and pathogenically closely related to Shigella species.
These strains carry a large virulence plasmid (pInv) that encodes the machinery for epithelial cell invasion.
Like Shigella, EIEC invades the epithelial cells of the colon, escapes the endocytic vacuole, multiplies within the cytoplasm, and spreads to adjacent cells using actin-based motility.
This invasive process causes severe inflammation, cell death, mucosal ulceration, and a dysentery-like syndrome characterized by blood, mucus, and inflammatory cells in the stool.
Let us review the other pathotypes:
-EPEC (Enteropathogenic E. coli): Causes watery diarrhea by forming "attaching and effacing" (A/E) lesions on intestinal microvilli, without intracellular invasion.
-ETEC (Enterotoxigenic E. coli): Produces heat-labile (LT) and/or heat-stable (ST) enterotoxins that cause secretory, watery diarrhea, but does not invade host cells.
-ECEC (Enteroadherent or similar pathotypes): Adheres to the mucosa without displaying the intracellular invasion typical of Shigella.

Step 3: Final Answer:
Shigella-like invasiveness is characteristic of Enteroinvasive Escherichia coli (EIEC).