Cefazolin-Related Acute Interstitial Nephritis with Associated Nephrotic-Range Proteinuria: A Case Report

A 67-year-old male with history of well controlled type 2 diabetes mellitus and hypertension developed acute interstitial nephritis(AIN) with nephrotic-range proteinuriaduring treatment with cefazolinfor methicillin-sensitive Staphylococcus aureus and Group B Streptococcus (GBS) bacteremia. The patient received intravenous cefazolin2 g every 8 h for 4 weeks prior to presentation to the emergency department with abdominal distension, nausea, and vomiting. Investigations revealed a serum ascites albumin gradientof 1.0 with total protein of 1.8 g/dL suggestive of nephrotic syndrome, which was confirmed with a spot urine protein/creatinine ratiothat estimated 7.95 g of protein per day. Serum creatininewas elevated compared with baseline. Urine studies showed sterile pyuriawith 3+ protein and eosinophiluria. The patient was diagnosed with AIN with nephrotic-range proteinuriaassociated with cefazolinuse. Cefazolinwas discontinued and, within a couple of days, the patient’s creatininestabilized. He was discharged with prednisone 60 mg once a day for 10 days with a taper over 2 weeks for his AIN. The patient’s creatinineand proteinuriaslowly decreased over the next couple of weeks, however, did not recover to baseline. A Naranjo assessment score of 6 was obtained, indicating a probable relationship between the patient’s AIN with nephrotic-range proteinuriaand his use of cefazolin.