This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urolithiasis, Subject name: Surgery
[{'content': 'Xanthogranulomatous pyelonephritis associated stones are due to infection with? \nSelect and explain. \nA. Proteus, B. E coli, C. Pseudomonas, D. Klebsiella', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) ProteusREF: Tarascon Pocket Urologica by Pamela Ellsworth page 8"Xanthogranulomatous pyelonephritis is a chronic condition of the kidney resulting in diffuse renal destruction, a grossly enlarged and nonfunctioning kidney associated with nephrolithiasis. It is thought to start with obstruction (stone or sloughed papilla) followed by infection (most commonly Proteus)"', 'role': 'assistant'}]