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Difficulty: HardInfectious Diseases

A 52-year-old man with newly diagnosed acute myeloid leukemia is evaluated on hospital day 10 of induction chemotherapy due to a new-onset fever. Over the past 4 hours, his temperature has risen to a maximum of 38.7°C (101.7°F). He reports mild generalized fatigue but denies cough, shortness of breath, dysuria, abdominal pain, or diarrhea. Vital signs show a blood pressure of 118/74 mmHg, pulse of 92/min, and respiratory rate of 16/min. He has an indwelling right internal jugular central venous catheter; examination of the insertion site reveals it to be clean and dry without any surrounding erythema, induration, or tenderness. Cardiopulmonary and abdominal examinations are unremarkable. There are no skin rashes or mucosal ulcerations. Laboratory studies reveal:

TestResult
Hemoglobin8.4 g/dL
Platelets45,000 /mm³
Leukocytes400 /mm³
Neutrophils15%

Peripheral blood and catheter-drawn blood cultures have been obtained. Which of the following is the most appropriate empiric antimicrobial regimen for this patient?

  1. A
    Intravenous cefepime and vancomycin
  2. B
    Oral ciprofloxacin and amoxicillin-clavulanate
  3. Intravenous cefepimeAnswer
  4. D
    Intravenous vancomycin and ciprofloxacin
  5. E
    Intravenous meropenem, vancomycin, and caspofungin

Answer

Intravenous cefepime
The correct approach for this patient is intravenous cefepime monotherapy. This patient has febrile neutropenia, defined as a single oral temperature ≥\geq 38.3°C (101°F) and an absolute neutrophil count (ANC) <500/mm3< 500/mm^3. Because he is undergoing induction chemotherapy for acute myeloid leukemia, he is at high risk for prolonged and profound neutropenia, necessitating immediate admission and empiric intravenous antibiotics. The standard of care for high-risk febrile neutropenia is monotherapy with an anti-pseudomonal beta-lactam (e.g., cefepime, meropenem, or piperacillin-tazobactam). Routine empiric addition of vancomycin is explicitly discouraged to prevent antimicrobial resistance and reduce toxicity, unless specific criteria are met (e.g., hemodynamic instability, severe mucositis, radiographic pneumonia, or a clinically infected catheter site).

Step-by-Step Solution

1
Calculate the Absolute Neutrophil Count (ANC) to diagnose febrile neutropenia.
ANC=400×0.15=60/mm3ANC = 400 \times 0.15 = 60/mm^3. Combined with a temperature ≥\geq 38.3°C, this confirms neutropenic fever.
Establishing the diagnosis and severity of neutropenia dictates the urgency and type of empiric therapy.
2
Risk-stratify the patient to determine the required setting and route of administration.
The patient has acute myeloid leukemia and is undergoing induction chemotherapy, predicting prolonged (>77 days) and profound (<100/mm3< 100/mm^3) neutropenia. This classifies him as high-risk, requiring inpatient intravenous therapy.
Low-risk patients can sometimes be managed with oral antibiotics, but high-risk patients require immediate broad-spectrum IV coverage.
3
Select the appropriate empiric antibacterial coverage.
Guidelines recommend monotherapy with an anti-pseudomonal beta-lactam (e.g., cefepime, meropenem, or piperacillin-tazobactam) for high-risk patients.
Patients with severe neutropenia are highly susceptible to rapidly fatal Gram-negative sepsis, particularly from Pseudomonas aeruginosa.
4
Evaluate for specific indications to add MRSA coverage (vancomycin).
The patient is hemodynamically stable and has a clean, non-tender central venous catheter site without severe mucositis or pneumonia. Therefore, vancomycin is NOT indicated.
Antimicrobial stewardship guidelines specifically advise against the routine empiric addition of vancomycin for fever in neutropenic patients unless targeted risk factors are present.

Key Concept

Empiric management of high-risk febrile neutropenia requires anti-pseudomonal beta-lactam monotherapy; vancomycin is reserved for specific indications such as hemodynamic instability or overt catheter-site infections, and should not be added solely because a central line is present.
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Topics

Infectious Diseases

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