A 14-year-old girl treated for pyelonephritis.

A 14-year-old girl was being treated for pyelonephritis and had been on ceftriaxone for 2 days as an inpatient. She presented with mild fever of 99.4°F, dysuria, suprapubic and fl ank tenderness, and costovertebral angle tenderness, which was consistent with pyelonephritis. Genital exam was normal. She was empirically started on ceftriaxone, and subsequently, the urine culture grew Escherichia coli, which was susceptible to ceftriaxone. Her dysuria resolved, and she had been afebrile for 24 hours before having lower back pain. The pain was excruciating, 10/10 in severity, non-radiating, aggravated by movement, and relieved somewhat by rest and analgesics. She denied having any tingling, numbness, or weakness in the lower extremities. She denied any trauma to the back before being admitted. Because the patient experienced pain, her suprapubic and costovertebral angle tenderness resolved. However, there was severe tenderness noted on the