A 28-year-old pregnant woman is admitted to the ICU, requiring norepinephrine to treat hypotension due to pyelonephritis from highly susceptible, pan sensitive Escherichia coli. Ultrasound imaging of the kidneys and bladder on admission was normal. She is treated with ceftriaxone for 2 days, with improvement in her pain, fever, and hypotension. However, on day 3 she develops a fever to 38.4 while still receiving intravenous antibiotic therapy. She has no new symptoms, and no costovertebral angle tenderness to palpation.
What is the MOST likely cause of her recrudescent fever?A. Emerging antibiotic resistance to ceftriaxone
Correct Answer: B
Perinephric and renal abscesses are uncommon conditions. Both tend to be insidious in nature with a subacute onset of vague or nonspecific symptoms. Most patients do not report symptoms typical of a urinary tract infection. The majority of patients with renal (Answer D) or perinephric (Answer C) abscesses have fever, chills, flank pain, and costovertebral angle tenderness. Abscesses generally develop over many days to weeks, and it is unlikely that this patient admitted with a normal renal ultrasound (which is common even in pyelonephritis) would develop an abscess within 48 hours, especially while clinically improving. Similarly, antibiotic resistance to ceftriaxone (Answer A) would require time to emerge and is unlikely to occur while on appropriate antibiotics for a short time period with improving clinical parameters. Thus, among the answers given, drug fever to ceftriaxone (Answer B) or another medication is the most likely cause of her fever.