A 52-year-old man is evaluated on the surgical ward for a new-onset fever. He is currently… — USMLE Step 2 CK

A 52-year-old man is evaluated on the surgical ward for a new-onset fever. He is currently on postoperative day 9 following an elective sigmoid colectomy for recurrent diverticulitis. His early postoperative course was complicated by a catheter-associated urinary tract infection diagnosed on postoperative day 2, for which his indwelling catheter was removed and he was started on intravenous piperacillin-tazobactam.

Currently, the patient reports feeling well and has been ambulating independently in the hallways. He has no abdominal pain, nausea, vomiting, dysuria, or shortness of breath. He is tolerating a regular diet.

Vital signs are as follows:

Parameter	Value
Temperature	39.1°C (102.4°F)
Blood pressure	126/78 mm Hg
Heart rate	82/min
Respiratory rate	14/min

Physical examination reveals a soft, non-tender abdomen with a clean, well-approximated surgical incision. There is no calf tenderness or edema. Lungs are clear to auscultation bilaterally.

Laboratory results:

Test	Result
Leukocyte count	8,200/mm³
Neutrophils	60%
Lymphocytes	28%
Eosinophils	12%
Hemoglobin	12.1 g/dL
Platelets	250,000/mm³

Urinalysis is clear with no leukocyte esterase or nitrites.

Which of the following is the most appropriate next step in management?

A
Obtain computed tomography of the abdomen and pelvis
B
Switch antibiotic therapy to intravenous meropenem
Discontinue piperacillin-tazobactamAnswer
D
Obtain blood cultures and continue current management
E
Perform lower extremity venous duplex ultrasonography

Answer

The most appropriate next step is to discontinue piperacillin-tazobactam, as the patient's presentation is consistent with drug-induced fever.

The correct answer is to discontinue piperacillin-tazobactam. This patient's clinical presentation is highly suggestive of drug-induced fever (the 'Wonder drugs' category of postoperative fever). Drug fever typically occurs 1 to 2 weeks after the initiation of the offending agent, making postoperative day 9 a classic timeframe for a medication started on day 2. Beta-lactam antibiotics, such as piperacillin-tazobactam, are common culprits. Classic features include a high fever in a patient who appears otherwise well, often accompanied by relative bradycardia (a lack of the expected 10 beat/min rise in heart rate per 1°C increase in temperature). In this case, the patient has a significant fever of 39.1°C but a relatively normal heart rate of 82/min. Eosinophilia, seen in this patient's laboratory results, is present in about 20% of cases and further supports the diagnosis. Because the patient has completed a sufficient 7-day course of antibiotics for a catheter-associated UTI and is currently asymptomatic with a normal urinalysis and normal total leukocyte count, the infection has resolved. The most appropriate next step is to discontinue the offending drug, which usually leads to resolution of the fever within 48 to 72 hours.

Step-by-Step Solution

Analyze the timeline and symptoms.

The patient developed a fever on postoperative day 9 but is completely asymptomatic and appears well.

Establishing the timeline narrows down the differential diagnosis based on the '5 Ws' of postoperative fever. A well-appearing patient with a new fever late in the postoperative course suggests a non-infectious etiology.

Evaluate the vital signs.

Temperature is elevated at 39.1°C (102.4°F), but the heart rate is only 82/min.

This identifies 'relative bradycardia' (a failure of the heart rate to increase by the expected 10 beats/min for every 1°C rise in temperature), which is a classic hallmark of drug fever.

Interpret the laboratory findings.

The total leukocyte count is normal, but the differential shows 12% eosinophils. Urinalysis is completely normal.

Eosinophilia strongly supports an allergic or drug-induced etiology rather than an acute bacterial infection. The normal urinalysis confirms the prior UTI has resolved.

Determine the appropriate intervention.

Discontinue piperacillin-tazobactam.

The original infection has been adequately treated (7 days of antibiotics). Stopping the offending drug is both safe and the definitive treatment for drug fever.

Key Concept

Drug fever should be suspected in a postoperative patient who develops a high fever 1 to 2 weeks after starting a medication (often antibiotics) but otherwise appears remarkably well, especially when accompanied by relative bradycardia and eosinophilia.

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