What is the appropriate antibiotic treatment for a young adult with Acute Myeloid Leukemia (AML) M5, presenting with fever and low hemoglobin prior to starting chemotherapy?

Treatment of Febrile Neutropenia in AML Prior to Chemotherapy

Initiate empirical broad-spectrum antibiotic therapy immediately with an anti-pseudomonal beta-lactam such as cefepime (a 3rd generation cephalosporin), as this is the standard first-line therapy for febrile neutropenia in AML patients and must be started within 1 hour of fever presentation to prevent sepsis and death. 1

Immediate Management Algorithm

First-Line Antibiotic Selection

• Start cefepime 2g IV every 8 hours (or equivalent anti-pseudomonal beta-lactam) as the empirical therapy of choice 1
• This patient has fever (38.9°C) one day before planned chemotherapy with documented AML M5, making him profoundly immunocompromised and at extreme risk for life-threatening bacterial infections 2
• The Infectious Diseases Society of America specifically recommends anti-pseudomonal beta-lactams as standard first-line therapy for febrile neutropenia 1

Why Not the Other Options?

Extended-spectrum penicillin (Option A): While anti-pseudomonal penicillins are acceptable alternatives, third-generation cephalosporins like cefepime are preferred as first-line agents with broader coverage and better CNS penetration 1

Granulocyte colony-stimulating factor (Option B): G-CSF is not indicated for treatment of established febrile neutropenia 3. Placebo-controlled studies found no significant differences in primary outcomes despite reduced neutropenia duration 3. G-CSF may be considered prophylactically in subsequent chemotherapy cycles if severe neutropenia develops, but not for acute fever management 3

Fluoroquinolone (Option C): This is prophylaxis, not treatment 3, 4. Fluoroquinolones are recommended for prophylaxis during expected prolonged neutropenia (ANC <100/mm³ for >2 weeks) to decrease gram-negative infections 3. However, once fever develops, empirical broad-spectrum therapy with anti-pseudomonal beta-lactams is mandatory 1. Fluoroquinolones alone are insufficient for treating established febrile neutropenia 5

Critical Management Steps

Before Starting Antibiotics

• Obtain blood cultures from peripheral vein and all indwelling catheters 1
• Check complete blood count with differential to document absolute neutrophil count 1
• Assess hemodynamic stability 1

Risk Stratification

This patient is high-risk because: 1

• Newly diagnosed AML undergoing remission-induction chemotherapy
• Prolonged neutropenia expected (ANC <500/μL for >7 days)
• Pre-chemotherapy timing suggests profound immunosuppression

Monitoring and Escalation

• Continue initial antibiotic therapy if afebrile and clinically stable at 48 hours 1
• If fever persists 3-7 days despite appropriate antibacterial therapy, add empirical antifungal therapy (liposomal amphotericin B or echinocandin) 1
• Continue antibiotics for minimum 7 days for patients who respond without microbiological documentation 1

Common Pitfalls to Avoid

• Never delay antibiotic initiation—start within 1 hour of fever presentation 1
• Never use fluoroquinolones alone for treatment of established febrile neutropenia; they are for prophylaxis only 3, 4
• Never stop antibiotics prematurely while evaluating persistent fever in neutropenic patients 1
• Never overlook non-bacterial causes of persistent fever, including invasive fungal infections, viral infections, and drug fever 1

Answer: D. 3rd generation cephalosporin

The correct answer is D (3rd generation cephalosporin) because empirical broad-spectrum antibiotic therapy with an anti-pseudomonal beta-lactam like cefepime is the standard of care for febrile neutropenia in AML patients and must be initiated immediately 1, 3.