A 20-year-old man presented with hemorrhagic colitis. The stool sample grew Escherichia coli in pure culture. The following serotype of E.coli is likely to be a causative agent –
## **Core Concept**
The question tests knowledge of specific serotypes of *Escherichia coli* (*E. coli*) associated with particular clinical syndromes. *E. coli* is a common cause of gastrointestinal infections, and certain serotypes are linked to specific types of infections, such as hemorrhagic colitis.
## **Why the Correct Answer is Right**
The correct answer, , is associated with **Shiga toxin-producing *E. coli* (STEC)**, previously known as **verocytotoxin-producing *E. coli* (VTEC)**. This serotype is a well-known cause of **hemorrhagic colitis**, which is characterized by bloody diarrhea, and can lead to life-threatening complications like **hemolytic uremic syndrome (HUS)**, especially in children. The Shiga toxin produced by these bacteria damages the intestinal lining and renal endothelial cells, leading to the clinical manifestations.
## **Why Each Wrong Option is Incorrect**
* **Option A:** - This serotype is commonly associated with **traveler's diarrhea** and other types of diarrheal illnesses but is not specifically linked to hemorrhagic colitis.
* **Option B:** - While certain strains can cause severe disease, is not specifically identified as a common cause of hemorrhagic colitis compared to .
* **Option D:** - This option might not directly correlate with a well-known serotype associated with hemorrhagic colitis or might be less commonly implicated compared to .
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that *E. coli* serotype is a leading cause of **foodborne outbreaks** of hemorrhagic colitis, often linked to undercooked ground beef or unpasteurized products. Early recognition and appropriate management are crucial to prevent complications like HUS.
## **Correct Answer:** .