Mrs. CD is a 49 years female who has been admitted in hospital for her road-side accident. She has S. aureus infection for which she was administered with intravenous nafcillin at a dose of 2 grams every four hours. On discharge, she was handed over a prescription of orally oxacillin at a dose of 500 milligram four-times daily. After two weeks, she was again admitted in the ED because of her fever, body rashes, blood in urine, and reduced urine urgency. Her blood biochemistry revealed a blood urea nitrogen level of 34 mg/dL, serum creatinine level of 2 mg/dL, and elevated white blood cells count. Urinalysis showed the fractional excretion of sodium as 3% and a positive test for the presence of eosinophils, and red blood cells. What is the likely diagnosis and how she can be treated?
The likely diagnosis is interstitial nephritis caused by allergy to oxacillin. Some studies demonstrated that this antibiotic can cause interstitial nephritis that is confirmed by the presence of red blood cells and eosinophils in urine. The possible treatment procedures comprise stopping the medication and use of steroid antiinflammatory drugs.