Febrile Neutropenia After Induction Chemotherapy
A 54-year-old man with newly diagnosed acute myeloid leukemia is on day 12 of induction chemotherapy. He develops fever 38.9°C and chills. His absolute neutrophil count is 80/µL, platelets 18,000/µL, hemoglobin 8.1 g/dL. Blood pressure 100/60 mmHg, pulse 112/min, respiratory rate 22/min, oxygen saturation 96% on room air. Examination shows mucositis but no skin abscess, no diarrhea, no pulmonary infiltrates on chest radiograph. Blood cultures are drawn, but results will take 48 hours. The hospital's antibiogram shows that 22% of Escherichia coli isolates are resistant to ceftriaxone and that Pseudomonas aeruginosa is susceptible to piperacillin-tazobactam in 85% of isolates. The resident wants to wait for culture results before starting antibiotics because the patient has no localizing signs. The patient has a penicillin allergy described as a mild rash.
1. Should antibiotics be delayed until cultures return? Justify your answer using the risk of death in febrile neutropenia.
Read the worked answer
Do not delay. Febrile neutropenia is a medical emergency; mortality rises with delayed antibiotics. Start empiric antibiotics within 60 minutes of fever, after blood cultures are drawn but without waiting for results. The absence of localizing signs is typical; mucositis and chemotherapy-induced mucosal damage are portals of entry. Cultures take 48 hours and may be negative, so they cannot guide the initial decision. Waiting would expose the patient to uncontrolled bacteremia and sepsis.
2. Choose an empiric regimen appropriate to this hospital's antibiogram and explain why ceftriaxone alone is inadequate.
Read the worked answer
Use an antipseudomonal beta-lactam such as piperacillin-tazobactam or cefepime. Piperacillin-tazobactam is supported by the local antibiogram, which shows 85% Pseudomonas susceptibility. Ceftriaxone alone is inadequate because it has no reliable Pseudomonas activity and 22% of E. coli are resistant. The mild rash penicillin allergy does not absolutely contraindicate cefepime, but if the reaction were severe, use aztreonam plus an appropriate gram-positive agent. Add vancomycin only if there is a specific indication.
3. When would you add vancomycin or an antifungal, and what cultures should be repeated?
Read the worked answer
Add vancomycin for suspected catheter-related infection, skin or soft tissue infection, pneumonia, hemodynamic instability, or known MRSA colonization. Add an antifungal after 4-7 days of persistent fever and ongoing neutropenia, after appropriate bacterial coverage and cultures. Repeat blood cultures from peripheral sites and the catheter, and culture mucositis or urine if symptoms. Do not start antifungals on day 1 without evidence.