An oncology clinic evaluates a patient undergoing induction chemotherapy for acute myeloid… — USMLE Step 2 CK

An oncology clinic evaluates a patient undergoing induction chemotherapy for acute myeloid leukemia who developed chills and a high temperature earlier today. The patient reports generalized weakness but denies cough, dysuria, abdominal pain, or skin changes. Vital signs show a temperature of $38.7^\circ\text{C}$ ( $101.7^\circ\text{F}$ ), blood pressure of $118/76\text{ mmHg}$ , heart rate of $105/\text{min}$ , and respiratory rate of $16/\text{min}$ . Physical examination is unremarkable, with clear lung fields and no induration or erythema at the central venous catheter site. Laboratory studies reveal a total leukocyte count of $800/\text{mm}^3$ with $10\%$ neutrophils and $5\%$ bands. After obtaining appropriate blood and urine cultures, which of the following is the most appropriate empiric pharmacotherapy?

Intravenous cefepimeAnswer
B
Intravenous cefepime and vancomycin
C
Intravenous ceftriaxone and azithromycin
D
Oral ciprofloxacin and amoxicillin-clavulanate
E
Intravenous fluconazole

Answer

Intravenous cefepime

The correct answer provides monotherapy with an antipseudomonal beta-lactam. Neutropenic fever is an oncologic emergency defined by an Absolute Neutrophil Count (ANC) <

500/\text{mm}^3

and a single temperature equivalent to

\geq 38.3^\circ\text{C}

(

101.0^\circ\text{F}

) or

\geq 38.0^\circ\text{C}

(

100.4^\circ\text{F}

) sustained for over 1 hour. This patient's ANC is

120/\text{mm}^3

. In high-risk patients (such as those with profound neutropenia from hematologic malignancies), prompt initiation of empiric bactericidal intravenous therapy covering Pseudomonas aeruginosa is mandated. Cefepime, piperacillin-tazobactam, and meropenem are the drugs of choice.

Step-by-Step Solution

Calculate the Absolute Neutrophil Count (ANC).

ANC = Total WBC x (% neutrophils + % bands). ANC =

800 \times (0.10 + 0.05) = 120/\text{mm}^3

An ANC <

500/\text{mm}^3

(or expected to decrease to <

500/\text{mm}^3

in 48 hours) combined with a fever defines febrile neutropenia.

Stratify the patient's risk to determine the treatment setting and route.

The patient is undergoing induction chemotherapy for AML and has profound neutropenia, making her a high-risk patient.

High-risk febrile neutropenia requires admission and intravenous broad-spectrum antibiotics, whereas selected low-risk patients may be treated orally as outpatients.

Select the appropriate empiric antibiotic regimen.

Intravenous antipseudomonal beta-lactam monotherapy (e.g., cefepime, meropenem, or piperacillin-tazobactam) is selected.

The patient is hemodynamically stable without signs of catheter infection or pneumonia, so MRSA coverage (vancomycin) is not empirically required.

Key Concept

The initial management of high-risk febrile neutropenia requires prompt initiation of an intravenous antipseudomonal beta-lactam antibiotic.

Estimated Time:1m 15s

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