Most important serotype of E coli causing hemolytic uremic syndrome –
**Core Concept**
Hemolytic uremic syndrome (HUS) is a complex condition characterized by the triad of hemolytic anemia, acute kidney injury, and thrombocytopenia. Certain serotypes of E. coli are associated with the development of HUS, particularly those that produce Shiga toxins.
**Why the Correct Answer is Right**
The most important serotype of E. coli causing HUS is O157:H7. This serotype is responsible for the majority of HUS cases worldwide. The pathogenesis of HUS involves the attachment of E. coli O157:H7 to the intestinal epithelium, followed by the production of Shiga toxins, which are potent inhibitors of protein synthesis. These toxins cause damage to the microvasculature, leading to the characteristic manifestations of HUS.
**Why Each Wrong Option is Incorrect**
**Option A:** Other serotypes of E. coli, such as O111 and O103, can also cause HUS, but O157:H7 is the most common and well-studied serotype.
**Option B:** E. coli O157:H7 is not the only bacterium that can cause HUS; other pathogens, such as Shigella and Salmonella, can also lead to this condition.
**Option C:** E. coli O157:H7 is a specific serotype, not a broad category of E. coli that can cause HUS.
**Clinical Pearl / High-Yield Fact**
E. coli O157:H7 is often associated with foodborne outbreaks, particularly those involving undercooked ground beef or unpasteurized apple cider.
**Correct Answer:** O157:H7