A 9-year-old boy is hospitalized for the management of acute myeloid leukemia. He recently… — USMLE Step 2 CK

A 9-year-old boy is hospitalized for the management of acute myeloid leukemia. He recently completed his first cycle of induction chemotherapy. Five days ago, he developed a fever of $39.4^\circ C$ ( $102.9^\circ F$ ) and was found to have an absolute neutrophil count (ANC) of $120/\mu L$ . Blood and urine cultures were drawn, and empiric intravenous cefepime was initiated.

Today (hospital day 6 of fever), his temperature remains elevated at $39.2^\circ C$ ( $102.6^\circ F$ ). His blood pressure is 105/65 mmHg, and heart rate is 110/min. Physical examination reveals a clean central venous catheter site with no surrounding erythema or tenderness. The lungs are clear to auscultation, and there are no oral lesions or skin rashes.

Laboratory studies today show:

Test	Result
Hemoglobin	$8.5\text{ g/dL}$
Leukocytes	$300/\mu L$
Absolute neutrophil count	$80/\mu L$
Platelets	$45,000/\mu L$

Blood cultures from admission and from two days ago have shown no growth. A chest radiograph reveals no infiltrates. Which of the following is the most appropriate next step in management?

A
Add intravenous vancomycin
B
Switch intravenous cefepime to intravenous meropenem
Add intravenous caspofunginAnswer
D
Administer granulocyte colony-stimulating factor
E
Discontinue intravenous cefepime and observe

Answer

The correct answer is adding an empiric intravenous antifungal agent such as caspofungin.

The correct answer is adding an empiric antifungal agent such as caspofungin. This patient has high-risk, profound, and prolonged febrile neutropenia. When fever lasts longer than 4 to 7 days despite appropriate broad-spectrum antibacterial therapy, patients are at a significantly increased risk for invasive fungal infections, most commonly from Candida and Aspergillus species. Because these infections are difficult to culture early and carry high mortality, guidelines mandate the addition of an empiric systemic antifungal agent (such as an echinocandin, liposomal amphotericin B, or voriconazole) while continuing the existing antibacterial regimen.

Step-by-Step Solution

Evaluate the clinical scenario and the timeline of the patient's symptoms.

The patient is a child with acute myeloid leukemia experiencing persistent febrile neutropenia on hospital day 6, despite receiving appropriate initial broad-spectrum antibacterial therapy with cefepime.

Establishing the duration of febrile neutropenia (4-7 days) is the critical branch point in fever management protocols for neutropenic patients.

Assess the patient for localizing signs of bacterial infection or clinical deterioration.

The patient is hemodynamically stable, has a clean central line site, no oral lesions, clear lungs, and negative serial blood cultures.

This rules out the immediate need for Gram-positive coverage (like vancomycin) or escalation of antibacterial therapy (like meropenem).

Determine the guideline-based next step for unresolved neutropenic fever.

Guidelines dictate that for fever persisting 4 to 7 days without an identified bacterial source in a profoundly neutropenic patient, empiric systemic antifungal therapy must be added.

These patients are at an exceptionally high risk for invasive fungal infections (e.g., Candida, Aspergillus), which can be rapidly fatal and are notoriously difficult to diagnose early with standard cultures.

Key Concept

In patients with high-risk, prolonged febrile neutropenia (persisting 4-7 days despite broad-spectrum antibacterial therapy), empiric systemic antifungal therapy must be added due to the high risk of invasive fungal infections.

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