This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
Most common cause of hemolytic uremic syndrome is – 
Select and explain. 
A. E.coli, B. Shigella, C. Salmonella, D. Psedonomis
A: E.coli
Answer: A: E.coli 
Explanation: Etiology of HUS

HUS usually follows an episode of acute gastroenteritis.
Less commonly, patient may present after an upper respiratory tract infection.
The organisms responsible are -
E.coli (most common) → EHEC (shiga toxin producing)           
Shigella dysenteriae     
Salmonella     
Bartonella   
Streptococcus pneumonia      
Campylobacter