An inpatient oncology service evaluates a 29-year-old man who developed a sudden fever. He… — USMLE Step 2 CK

An inpatient oncology service evaluates a 29-year-old man who developed a sudden fever. He is currently on day 12 of induction chemotherapy for acute myeloid leukemia. He reports feeling profoundly fatigued but denies cough, shortness of breath, dysuria, abdominal pain, or diarrhea. Vital signs show a temperature of 38.9°C (102.0°F), blood pressure of 118/74 mm Hg, pulse of 98/min, and respirations of 16/min. Physical examination reveals clear lung fields bilaterally, no cardiac murmurs, and a non-tender abdomen. The insertion site of his right internal jugular central venous catheter is clean, dry, and intact with no surrounding erythema, induration, or purulent discharge. Laboratory studies are significant for a leukocyte count of $300/\text{mm}^3$ with $10\%$ neutrophils (Absolute Neutrophil Count = $30/\text{mm}^3$ ). Which of the following is the most appropriate next step in the management of this patient?

A
Obtain blood cultures and initiate intravenous cefepime and vancomycin
B
Obtain blood cultures and initiate oral levofloxacin and amoxicillin-clavulanate
Obtain blood cultures and initiate intravenous cefepimeAnswer
D
Obtain blood cultures and initiate intravenous meropenem and fluconazole
E
Obtain blood cultures and initiate intravenous linezolid and ciprofloxacin

Answer

Obtain blood cultures and initiate intravenous cefepime.

This patient has high-risk febrile neutropenia, defined by an absolute neutrophil count

< 500/\text{mm}^3

(here

30/\text{mm}^3

) alongside profound expected immunosuppression from acute myeloid leukemia induction therapy. In high-risk febrile neutropenia, the most common life-threatening pathogens include Gram-negative organisms, particularly Pseudomonas aeruginosa. The standard of care is to immediately draw blood cultures and begin empiric intravenous monotherapy with an anti-pseudomonal beta-lactam, such as cefepime, meropenem, or piperacillin-tazobactam. Gram-positive coverage (e.g., vancomycin) is not routinely recommended unless the patient exhibits hemodynamic instability, signs of severe catheter-related infection (erythema/purulence at the site), severe pneumonia, or known colonization with MRSA. Because this patient is hemodynamically stable and has a benign exam, cefepime monotherapy is the most appropriate next step.

Step-by-Step Solution

Calculate the Absolute Neutrophil Count (ANC) and identify the clinical syndrome.

ANC is

300 \times 0.10 = 30/\text{mm}^3

. Since ANC is

< 500/\text{mm}^3

and the patient has a single oral temperature of

\geq 38.3°C

(

101.0°F

), the diagnosis is neutropenic fever.

Establishing the diagnosis of febrile neutropenia dictates an immediate algorithm for life-saving empiric antibiotic therapy.

Stratify the patient's risk level to determine the route and setting of care.

The patient has a hematologic malignancy (AML) undergoing induction chemotherapy, anticipating prolonged (

> 7

days) and profound (ANC

< 100/\text{mm}^3

) neutropenia. This classifies him as high-risk.

High-risk patients must be admitted (or remain inpatient) and receive intravenous, bactericidal antibiotics rather than oral step-down regimens.

Select the appropriate empiric antimicrobial regimen based on the patient's specific physical exam findings.

The patient has stable vital signs, clear lungs, and a benign central line insertion site. Monotherapy with an anti-pseudomonal beta-lactam (e.g., cefepime, piperacillin-tazobactam) is indicated. Vancomycin is not added.

Routine use of vancomycin in all febrile neutropenic patients increases toxicity and resistance. It is strictly reserved for those with hemodynamic instability, obvious catheter-site infection, skin/soft tissue infection, or severe pneumonia.

Key Concept

Empiric Management of High-Risk Febrile Neutropenia

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