Possible case of nafcillin-induced acute interstitial nephritis.

To report a case of acute interstitial nephritis (AIN) secondary to nafcillin. A 55-year-old Hispanic man (height, 63 in.; weight, 61.2 kg) with a history of deep vein thrombosis in the right lower extremity, hypertension, hyperlipidemia, and hepatitis C infection was admitted to the hospital with right-sided chest pain that radiated down his right arm and leg. The patient was diagnosed with methicillin-sensitive Staphylococcus aureus endocarditis. A renal ultrasound was performed on hospital day 9 after the patient developed acute renal failure and showed diffusely increasing echogenicity of the renal parenchymal bilaterally with an interpolar cyst in the left kidney. A urine analysis, serum chemistry panels, and complete blood counts were consistent with AIN. The patient received a total of seven days of nafcillin, and cefazolin was initiated. A renal ultrasound and renal biopsy were performed, which confirmed the diagnosis of AIN. The patient received short-term hemodialysis, after which his renal function slowly returned to baseline. He then underwent an aortic valve replacement and tricuspid valve repair. His antibiotics were changed to rifampin and vancomycin after methicillin-resistant S. aureus was found in an aortic valve culture on hospital day 26. Cefazolin was discontinued 3 days after rifampin and vancomycin were added. The patient received 18 more days of antibiotics and was discharged on the last day of therapy (hospital day 45). A 55-year-old, critically ill man developed a possible case of nafcillin-induced AIN after receiving a 7-day course of treatment with the drug.