Biopsy-proven granulomatous interstitial nephritis associated with vancomycin in an adult patient: a case report.

Acute kidney injury (AKI) caused by vancomycin mainly manifests as acute interstitial nephritis or acute tubular necrosis. Here, the rare case of a 71-year-old female patient with no history of kidney disease, who was diagnosed with granulomatous interstitial nephritis associated with vancomycin, is reported. The patient had been treated with vancomycin for over a month for an abscess in her right thigh. She presented to the emergency department with a history of fever, scattered rash, oliguria and elevated serum creatinine for >10 days. After hospitalization, the vancomycin trough concentration was confirmed to be >50 µg/ml. The patient received furosemide and continuous renal replacement therapy for AKI, teicoplanin and piperacillin/tazobactam for pulmonary infection, and urapidil, sodium nitroprusside and nifedipine for elevated blood pressure. Percutaneous ultrasound-guided kidney biopsy was performed. Light microscopy revealed granuloma formation, and diffuse infiltration of lymphocytes, monocytes, eosinophils, and some multinucleated giant cells. Finally, the patient was diagnosed with vancomycin-induced granulomatous interstitial nephritis and was treated with high-flux haemodialysis and 16 mg oral methylprednisolone, daily, for 3 weeks, which contributed to a significant recovery of renal function. This case suggests the need for regular vancomycin concentration testing during treatment. When AKI due to vancomycin occurs, a renal biopsy may be performed to help diagnose and treat the condition.