ANCA Alert: A Curious Case of Amikacin-Induced Vasculitis

Introduction: Drug induced-antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is commonly caused by medications such as hydralazine, propylthiouracil, methimazole, and minocycline, but to date, amikacin has not been reported in the literature.We present the first case of AAV with renal involvement with amikacin as the unusual culprit. With this case a collaborative effort was called for to initiate plasma exchange (PLEX) and to start the novel C5a receptor inhibitor avacopan. Case Description: We present a 60-year-old male with benign prostatic hyperplasia who presented with generalized weakness, fevers, and weight loss of approximately 20 pounds in three weeks. The patient was recently treated for a urinary tract infection with 10 doses of amikacin. On admission labs demonstrated sodium 127 mmol/L, BUN 61 mg/dL, creatinine 2.48 mg/dL, and albumin 1.7 g/dL. Imaging was suggestive of pyelonephritis. Empiric piperacillin-tazobactam and intravenous fluids were started. The initial impression of the patient's kidney injury was due to pyelonephritis, hypovolemia, and urinary retention. On hospital day 3, BUN/Cr rose to 57/4.37, urine sodium at 56, urine total protein 59, and microalbumin-creatinine ratio 342 mg/g. Comprehensive workup for nephrotic syndrome was only pertinent for myeloperoxidase (MPO) Ab >8. Amikacin level was <0.8. Renal function continued to decline and a renal biopsy was performed, demonstrating pauci-immune glomerulonephritis with 70% crescents without significant chronic changes, suggestive of AAV with renal involvement, suspected to be induced by amikacin. PLEX and methylprednisolone were started. The patient was discharged on prednisone with plans for outpatient rituximab and avacopan. Discussion: Amikacin-induced AAV has not been reported in literature to our knowledge, but should be considered when no other common medications are implicated. In this scenario alternative diagnoses were excluded before arriving at this conclusion. Despite questionable mortality and ESRD benefit in AAV, PLEX was initiated as the patient approached the need for dialysis. Plasma exchange and steroids resulted in significant improvement in renal function shortly after initiation which can be associated with return of renal function and creatinine apheresis. As we learn more about renal involvement in AAV, the list of causative agents expands.