Broad-Spectrum Antibiotic Regimen for Febrile Patients with New Leukocytosis

Initial Assessment and Antibiotic Selection

For febrile patients with new leukocytosis, a combination of an anti-pseudomonal beta-lactam with an aminoglycoside is recommended as the standard empiric therapy, especially in those with severe and persistent granulocytopenia who are suspected of having Gram-negative bacillary bacteremia 1, 2
Prolonged neutropenia, low absolute neutrophil count, significant comorbidities, hemodynamic instability, or organ dysfunction should be considered high-risk features requiring aggressive treatment 2
Fever may be the only symptom of infection in neutropenic patients, requiring vigilance even with low-grade fever 2
Blood cultures from peripheral vein and all indwelling catheters should be obtained before starting antibiotics 2
First-line therapy: Anti-pseudomonal beta-lactam with antipseudomonal activity (monotherapy or combination therapy) 3, 2
For high-risk patients, combination therapy with an aminoglycoside provides synergistic effects against Gram-negative bacteria 1, 2

Perform daily assessment of fever trends, bone marrow and renal function until the patient is afebrile and absolute neutrophil count ≥0.5×10⁹/L 2
Reassess response to therapy at 48-72 hours 2
If fever persists after 3-4 days despite initial antibiotics, consider modifying the regimen 5, 2
For persistent fever, consider adding antifungal therapy with amphotericin B, especially if severe and persistent granulocytopenia continues 5, 2

For patients who respond to empiric therapy without microbiological documentation, a total of 7 days of treatment is recommended; the aminoglycoside can probably be discontinued earlier in most cases 5
Consider discontinuing antibiotics if neutrophil count ≥0.5×10⁹/L, patient is asymptomatic and afebrile for 48 hours, and blood cultures are negative 2
For persistent fever without microbiological documentation (fever of unknown origin), broad-spectrum antibiotics should be continued if severe and persistent granulocytopenia remains, as discontinuation may be associated with fatal bacteremia 5

Delaying antibiotic initiation - start antibiotics within 1 hour of presentation 2
Failure to consider non-bacterial causes of persistent fever, including fungal infections, viral infections, and drug fever 2
Unnecessary prolonged use of broad-spectrum antibiotics in patients who have recovered from neutropenia and are afebrile 2
Overlooking drug interactions - many antifungals (especially azoles) can interact with other medications through CYP3A4 inhibition 6

For patients with acute leukemia or aggressive hematologic malignancy, empirical broad-spectrum antibiotic therapy during chemotherapy is strongly recommended 6, 7