An oncology team is evaluating a 47-year-old male inpatient who has had persistent fever d… — USMLE Step 2 CK

An oncology team is evaluating a 47-year-old male inpatient who has had persistent fever despite ongoing antimicrobial therapy. He has been hospitalized for the past $16$ days receiving induction chemotherapy for acute myeloid leukemia. Six days prior to the current evaluation, his absolute neutrophil count dropped to $90/\text{mm}^3$ , coinciding with a new-onset fever of $39.2^\circ\text{C}$ ( $102.6^\circ\text{F}$ ). At that time, comprehensive pan-culturing was performed, and empiric intravenous piperacillin-tazobactam was initiated.

Currently, the patient's temperature is $38.9^\circ\text{C}$ ( $102.0^\circ\text{F}$ ), blood pressure is $122/78 \text{ mmHg}$ , and pulse is $95/\text{min}$ . He reports feeling exhausted but has no focal symptoms such as cough, dyspnea, sinus pain, or dysuria. Physical examination reveals a clean, non-tender central venous catheter insertion site. Cardiopulmonary and abdominal examinations are unremarkable. The absolute neutrophil count remains profoundly low at $40/\text{mm}^3$ . All previous blood and urine cultures have remained sterile after six days of incubation. High-resolution computed tomography of the chest demonstrates no pulmonary nodules or infiltrates.

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

Add intravenous caspofunginAnswer
B
Add intravenous vancomycin
C
Switch piperacillin-tazobactam to meropenem
D
Discontinue piperacillin-tazobactam and start intravenous liposomal amphotericin B
E
Continue the current regimen and observe closely

Answer

The most appropriate next step is to add an empiric antifungal agent, such as intravenous caspofungin.

Adding intravenous caspofungin is the correct next step. The patient has persistent neutropenic fever, defined as a fever lasting longer than 4 to 7 days despite receiving appropriate initial empiric broad-spectrum antibacterial therapy (in this case, piperacillin-tazobactam). In high-risk patients (such as those with profound neutropenia from induction chemotherapy), persistent fever often indicates an occult invasive fungal infection, most frequently involving Candida or Aspergillus species. Standard of care requires the addition of empiric antifungal therapy with an echinocandin (like caspofungin), a mold-active azole, or liposomal amphotericin B while continuing the antibacterial regimen until the neutrophil count recovers.

Step-by-Step Solution

Identify the patient's primary clinical syndrome.

The patient has high-risk, prolonged neutropenic fever (ANC

< 500/\text{mm}^3

) that has persisted for 6 days despite appropriate initial empiric antibacterial therapy.

Recognizing the timeline and the unresponsiveness to piperacillin-tazobactam is critical for determining the next phase of the management algorithm.

Assess the risk of secondary or occult infections.

Patients with profound and prolonged neutropenia are at an exceptionally high risk for invasive fungal infections, most commonly caused by Candida and Aspergillus species.

Fungal pathogens are a common cause of culture-negative persistent fever in hematologic malignancy patients undergoing induction chemotherapy.

Apply the standard treatment protocol for persistent neutropenic fever.

Guidelines dictate that if a high-risk neutropenic patient remains febrile after 4 to 7 days of broad-spectrum antibacterial therapy and has no identified source, an empiric antifungal agent must be added.

Early initiation of antifungal therapy reduces mortality from occult invasive fungal infections in this vulnerable population.

Select the appropriate pharmacotherapy to add.

Adding intravenous caspofungin (an echinocandin) provides excellent empiric coverage for the suspected fungal organisms.

Echinocandins, liposomal amphotericin B, or mold-active azoles are the drugs of choice in this scenario.

Key Concept

In high-risk patients with neutropenic fever that persists for 4 to 7 days despite appropriate broad-spectrum antibacterial therapy, empiric antifungal coverage (e.g., caspofungin) should be added to prevent severe morbidity and mortality from invasive fungal infections.

Estimated Time:1m 30s

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