Question
Identify the organism which shows effacement and attachment of intestinal cells as shown below?
| A. |
EPEC
|
| B. |
ETEC
|
| C. |
Enterohemorrhagic ecoli
|
| D. |
Diffusely enteroadherent ecoli
|
Show Answer
|
Correct Answer � A
Explanation
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|
Ans. A. EPEC
Enteropathogenic E.coli (EPEC)
- EPEC frequently cause infantile diarrhea.
- Nontoxigenic and noninvasive
Mechanism of diarrhea:
- Adhesion to intestinal mucosa mediated by plasmid coded bundle-forming pili.
- A/E lesions (attaching & effacing lesions) on the intestinal epithelium.
- Endotoxin in the cell wall causes septic shock. Two enterotoxins are produced by enterotoxigenic E.coli (ETEC) strains.
- The heat-labile toxin (LT) stimulates adenylate cyclase by ADP-ribosylation. Increased cyclic AMP causes an outflow of chloride ions and water, resulting in diarrhea.
- The heat-stable toxin (ST) causes diarrhea, perhaps by stimulating guanylate cyclase. Virulence factors include pili for attachment to mucosal surfaces and a capsule that impedes phagocytosis.
- Shiga toxin (verotoxin) is an enterotoxin produced by E. coli strains (STEC) with the O157: H7 serotype.
- It causes bloody diarrhea and hemolytic-uremic syndrome associated
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