Renal azotemia

A 59-year-old male inpatient is reviewed on the neurosurgical ward because of a decline in renal function over the past twenty-four hours. His notes show that he was hospitalized for resection of a right frontal brain tumor seven days ago. The notes also show that he developed a fever of 38.5 °C (101.3 °F) three days ago. At that time a chest X-ray showed a right lobe opacity consistent with aspiration pneumonia, for which he was started on piperacillin-tazobactam. His current temperature is 37.1 °C (98.7 °F), pulse is 89/min, respirations are 16/min, blood pressure is 135/85 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 94 percent. Examination show that his mucous membranes appear moist. Urinalysis shows trace protein, trace leukocytes, negative leukocyte esterase, and leukocyte casts. Laboratory investigations show:

Which of the following etiologies best explains this patient’s acute kidney injury?