Xanthogranulomatous pyelonephritis caused by methicillin-resistant Staphylococcus aureus.

Localized xanthogranulomatous pyelonephritis due to methicillin-resistant Staphylococcus aureus developed in a 41-year-old diabetic patient. She had recurrent bacteremia despite appropriate therapy with vancomycin. Nephrectomy was required for cure and clinical diagnosis. This report emphasizes differences in the clinical presentation and pathogenesis of xanthogranulomatous pyelonephritis caused by S. aureus. Compared with the common form of xanthogranulomatous pyelonephritis caused by gram-negative bacilli, the localized disease due to S. aureus probably results from hematogenous seeding and is not associated with nephrolithiasis or ureteral obstruction. Furthermore, this report indicates that xanthogranulomatous pyelonephritis may be caused by methicillin-resistant S. aureus, a rapidly emerging nosocomial pathogen.