Xanthogranulomatous pyelonephritis is most often due to
Xanthogranulomatous pyelonephritis occurs when a chronic urinary obstruction (often by staghorn calculi), together with chronic infection, leads to the suppurative destruction of renal tissue.Proteus infection is associated with staghorn formation.Ref: Harrison; 19th edition; Page no: 1033
E. coli
Proteus
Pseudomonas
Klebsiella
C.V.S