This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Pediatrics
[{'content': 'Most common cause of hemolytic uremic syndrome is: \nSelect and explain. \nA. E. coli, B. Shigella, C. Salmonella, D. Pseudomonas', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. E. coli(Ref: Nelson's 20/e p 2508-2510, Ghai 8/e p 492-493)Etiology of HUS: HUS usually follows an episode of acute gastroenteritis (less commonly, upper respiratory infection).The organisms responsible for HUS are:E. coli (most common) esp EHEC (shiga toxin producing)Salmonella; Shigella dysenteriaeStreptococcus pneumoniaeBartonella; CampylobacterViruses (Coxsackie virus, echovirus, influenza, varicella, HIV, EBV)", 'role': 'assistant'}]