All of the following cause hemolytic uremic syndrome except –
**Core Concept**
Hemolytic uremic syndrome (HUS) is a complex condition characterized by the triad of microangiopathic hemolytic anemia, acute kidney injury, and thrombocytopenia. It is often triggered by an infectious or toxic insult that leads to endothelial damage and the activation of the coagulation cascade.
**Why the Correct Answer is Right**
Hemolytic uremic syndrome is typically associated with Shiga toxin-producing Escherichia coli (E. coli) infections, such as those caused by serotype O157:H7. The toxin disrupts the endothelial cell barrier, leading to the formation of microthrombi and the activation of the complement system. This results in the characteristic hemolytic anemia, renal failure, and thrombocytopenia seen in HUS.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Shigella dysenteriae type 1, which produces Shiga toxin, is a well-known cause of HUS. The toxin is similar to that produced by E. coli O157:H7 and causes similar endothelial damage.
**Option B:** This option is incorrect because certain strains of Salmonella, such as Salmonella Typhimurium, can also produce Shiga-like toxins that lead to HUS. These toxins are structurally and functionally similar to the Shiga toxin produced by E. coli O157:H7.
**Option C:** This option is incorrect because Staphylococcus aureus, particularly the enterotoxin-producing strains, can cause hemolytic uremic syndrome, especially in the context of food poisoning or bacteremia.
**Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that HUS is often preceded by a diarrheal illness, and the presence of bloody diarrhea should raise suspicion for a Shiga toxin-producing E. coli infection.
**Correct Answer: D.**