A 29-year-old woman presents to the emergency department with a three-day history of fever, chills, and severe flank pain on the right side. She reports associated symptoms of dysuria, increased urinary frequency, and urgency. She mentions that her symptoms began after experiencing a urinary tract infection (UTI) a week ago, which she treated with over-the-counter medication but did not complete a course of antibiotics.

On examination, she is febrile with a temperature of 102°F (39°C), and there is tenderness in the right flank. Laboratory tests reveal an elevated white blood cell count and urine analysis shows pyuria, bacteriuria, and moderate hematuria. A urine culture grows Escherichia coli, confirming the presence of the bacteria responsible for the infection. A renal ultrasound is performed, which shows no obstruction.

The patient is diagnosed with acute pyelonephritis and is started on intravenous antibiotics for immediate treatment. She is advised to stay hydrated and is monitored closely for any complications. After a few days of treatment, she shows significant improvement and is discharged with a prescription for oral antibiotics to complete the course and instructions to follow up with her primary care physician.