Pyelonephritis
（重定向自Xanthogranulomatous pyelonephritis）
![A color photomicrograph, demonstrating macrophages and giant cells in a case of xanthogranulomatous pyelonephritis.](/Images/godic/202502/21/Xanthogranulomatous_pyelonephritis_cd683517.jpg")
Pyelonephritis /paɪəloʊnəˈfraɪtɪs/ (from Greek πύελο|ς pýelo|s, "basin" + νεφρ|ός nepʰrós, "kidney" + suffix -itis suggesting "inflammation") is an inflammation of the kidney tissue, calyces, and renal pelvis. It is commonly caused by bacterial infection that has spread up the urinary tract or travelled through the bloodstream to the kidneys.