A 51-year-old woman developed an acute onset of renal dysfunction acco
mpanied by rash, lumbar pain, arthralgias, fever, eosinophiluria, and
an elevated serum creatinine after 6 days of intravenous piperacillin-
tazobactam therapy. On discontinuing piperacillin-tazobactam and after
a 21-day course of prednisone, the patient's constitutional symptoms
dissipated and her renal function returned to baseline. Acute intersti
tial nephritis has been reported as an adverse effect of many drugs, i
ncluding antibiotics, but not, to our knowledge, after piperacillin-ta
zobactam. The time course of events suggested that piperacillin-tazoba
ctam was the cause of acute interstitial nephritis in this patient.