Neutropenic Fever

Medical emergency — fever ≥38.3°C (101°F) or ≥38.0°C × 1h in a patient with ANC <500/mm³ (or <1000 and falling); time to antibiotics is critical

Symptoms / Associated Sx

  • Fever (may be the ONLY sign — neutropenia blunts inflammatory response; no pus, no consolidation, no peritoneal signs)

  • Chills, rigors, diaphoresis

  • Fatigue, malaise, hypotension (septic shock)

  • Mouth sores, mucositis (chemotherapy-related)

  • Diarrhea (C. diff, typhlitis)

  • Perirectal pain or cellulitis (rectal abscess without fluctuance)

Denies

  • Note: classic signs of infection are ABSENT in neutropenia — do not expect focal signs; assume systemic infection with any fever

  • Recent antifungal (reduces invasive fungal infection likelihood)

  • Catheter removal (rules out catheter-related BSI if never had one)

Social History (SHx)

Type of malignancy, current chemotherapy regimen and last cycle date, prior neutropenic infections (especially prior Pseudomonas, MRSA, resistant organisms), prior antifungal prophylaxis, central venous catheter (CVC) presence, recent procedures, G-CSF use, transplant status.

Main Etiology

  • Gram-negative rods: E. coli, Klebsiella, Pseudomonas aeruginosa (most feared — rapid mortality)

  • Gram-positive cocci: Staph epidermidis, Staph aureus, Streptococcus viridans, Enterococcus (CVC-related)

  • Anaerobes (GI source — mucositis, typhlitis)

  • Fungi: Candida (early), Aspergillus (prolonged neutropenia >7 days)

  • Viral: HSV, CMV, VZV (mucositis, reactivation)

  • No source found in ~50% of cases (fever of unknown origin in neutropenia)

Most Common DDx

  • Drug fever (chemotherapy, antibiotics, biologics — temporal relationship; no source found; blood cultures negative; resolves after stopping offending agent)

  • Tumor fever (lymphoma, leukemia, myeloma — recurrent low-grade; negative cultures; may respond to NSAIDs; diagnosis of exclusion)

  • Typhlitis (neutropenic enterocolitis — RLQ pain + fever; CT shows cecal wall thickening; bowel rest + antibiotics ± surgery if perforation)

  • Central line-associated bloodstream infection (CLABSI) — catheter site erythema; fever within hours of flush; blood cultures through and peripheral; catheter removal if MRSA, Candida, or no response to antibiotics)

  • Mucositis-related bacteremia (oral streptococcal bacteremia from GI mucosal breakdown — blood cultures positive; severe cytarabine-related mucositis)

  • Invasive fungal infection (Aspergillus in prolonged neutropenia >7 days; halo sign on CT chest; galactomannan elevated; empiric antifungal indicated)

DATA

  • CBC with differential (ANC calculation — ANC = WBC × % neutrophils + % bands)

  • Blood cultures × 2 sets (one from each lumen of CVC if present; one peripheral) — BEFORE antibiotics; results in 24–48h

  • BMP (electrolytes, creatinine, glucose)

  • LFTs (hepatic toxicity, drug reaction, candidemia)

  • Procalcitonin (bacterial infection marker; elevated in bacteremia; useful for antibiotic stewardship decisions)

  • Lactate (septic shock)

  • UA + urine culture

  • CXR (pneumonia, pulmonary infiltrate — Aspergillus)

  • CT chest if CXR unremarkable and persistent fever + prolonged neutropenia >5 days (halo sign, nodules → invasive fungal)

  • CT abdomen/pelvis (typhlitis — cecal wall thickening; abdominal source)

  • Serum galactomannan (Aspergillus antigen) and beta-D-glucan (fungal wall component — Candida, Aspergillus) if prolonged fever >4–7 days or high-risk

  • MASCC or CISNE score (risk stratification — low-risk → consider outpatient oral antibiotics)

Home Meds

  • Chemotherapy agents (note last cycle; nadir timing; expected duration of neutropenia)

  • G-CSF (filgrastim/pegfilgrastim — assess use; continue if already prescribed)

  • Prophylactic antibiotics (fluoroquinolone prophylaxis — note if on levofloxacin → select non-fluoroquinolone empiric therapy)

  • Antifungal prophylaxis (fluconazole, posaconazole, voriconazole — note coverage)

  • Antiviral prophylaxis (acyclovir/valacyclovir for HSV prophylaxis — continue)

Plan

  • Time to antibiotics <60 minutes from triage — this is a mortality-reducing intervention

  • Empiric antibiotic therapy (high-risk patients — ANC <100 or expected prolonged neutropenia >7 days):

    • First-line: Piperacillin-tazobactam 4.5 g IV q6h OR Cefepime 2 g IV q8h

    • Meropenem 1 g IV q8h (if: prior resistant gram-negatives, septic shock, history of ESBL/carbapenem-resistant organisms, abdominal source)

    • Add Vancomycin 15–25 mg/kg IV q8–12h if: catheter-related infection suspected, skin/soft tissue infection, pneumonia, hemodynamic instability, prior MRSA, mucositis with gram-positive bacteremia risk

    • Do NOT add vancomycin routinely — de-escalate at 48–72h if no gram-positive growth

  • Low-risk neutropenic fever (MASCC ≥21 — solid tumor, no comorbidities, outpatient onset):

    • Ciprofloxacin 500 mg PO BID + Amoxicillin-clavulanate 875 mg PO BID (if NOT on quinolone prophylaxis)

    • Oral regimen only if reliable home monitoring, ability to return, no GI intolerance

  • Antifungal coverage (add empirically if):

    • Fever persisting >4–7 days on antibiotics + no source identified + prolonged neutropenia >7 days

    • Fluconazole 400 mg IV/PO daily (Candida coverage; NO Aspergillus coverage)

    • Voriconazole 6 mg/kg IV q12h × 2 doses → 4 mg/kg IV q12h (if Aspergillus suspected — halo sign, nodules on CT, galactomannan positive)

    • Caspofungin 70 mg IV × 1 → 50 mg IV daily (if Candida invasive or fluconazole-resistant)

  • G-CSF (filgrastim 5 mcg/kg SQ daily): Use if prolonged neutropenia >7 days expected; consider to shorten duration of neutropenia; do NOT routinely add in uncomplicated neutropenic fever if ANC expected to recover soon

  • Remove CVC if: Candida BSI, MRSA BSI, non-responding gram-negative bacteremia, tunnel infection

  • Antibiotic de-escalation at 48–72h based on culture results and clinical response

  • Duration: until ANC ≥500 × 2 days + afebrile × 48h + clinical stability

  • Blood cultures every 24–48h until afebrile + ANC recovering

  • Daily CBC (ANC trending); BMP; CXR if pulmonary symptoms develop

  • Strict neutropenic precautions (no fresh flowers/plants, HEPA filter rooms preferred, low-microbial diet, hand hygiene)

  • Oncology + hematology consult

  • PT/OT if prolonged admission or deconditioning

  • Discharge: Continue antibiotics until ANC ≥500; step-down to oral (ciprofloxacin + amoxicillin-clavulanate) when tolerating PO; oncology follow-up within 1 week; education on early fever recognition and return

Red Flags

  • ANC <100 + fever → highest risk; initiate IV antibiotics within 60 minutes; admit all patients

  • Septic shock in neutropenic patient → ICU; meropenem + vancomycin + antifungal empirically; ARDS, multiorgan failure possible

  • Typhlitis (neutropenic enterocolitis — RLQ pain + cecal wall thickening on CT) → bowel rest + broad antibiotics + surgery consult (perforation risk)

  • Persistent fever >7 days on antibiotics → CT chest for Aspergillus halo sign; add voriconazole or caspofungin empirically

  • CVC line infection with Candida or MRSA → remove catheter immediately; do not treat through

Senior IM Resident Pearls

  • MASCC score ≥21 = low risk: solid tumor, outpatient status at fever onset, no hypotension, no COPD, no fungal infection, no dehydration, age <60 — candidates for oral antibiotics and possibly outpatient management

  • ANC calculation: WBC × (% neutrophils + % bands) ÷ 100 — do this manually; automated differential can miss bands

  • Halo sign on CT chest = ground-glass opacity surrounding pulmonary nodule → invasive Aspergillus until proven otherwise → voriconazole empirically; galactomannan from BAL > serum for sensitivity

  • Vancomycin de-escalation at 48–72h if no gram-positive growth — reduces nephrotoxicity risk; do not continue routinely without indication

  • Common mistake: Waiting for a localizing source before starting antibiotics in neutropenic fever — the source may be silent; start empiric therapy within 60 minutes of fever recognition regardless of localization

  • Common mistake: Using fluoroquinolone empirically when patient is on fluoroquinolone prophylaxis — select a different antibiotic class; resistance is expected in breakthrough infections on prophylaxis

Labs

  • CBC with differential (calculate ANC)

  • CMP

  • Magnesium

  • Phosphorus

  • LFTs

  • Procalcitonin

  • Lactate

  • Blood cultures ×2 BEFORE antibiotics

    • 1 peripheral

    • 1 from each CVC lumen if present

  • UA

  • Urine culture

If Persistent Fever

  • Repeat blood cultures q24–48h

  • Serum galactomannan

  • Beta-D-glucan

  • Respiratory viral panel

  • COVID/Flu PCR

  • C. difficile PCR if diarrhea

Trending

  • CBC daily

  • ANC daily

  • CMP daily

  • LFTs daily

  • Blood cultures until afebrile and cultures clear

Imaging

  • CXR on admission

If Persistent Fever (>4–7 days)

  • CT Chest w/ contrast

  • Evaluate for invasive fungal infection

If Abdominal Pain

  • CT Abdomen/Pelvis w/ contrast

  • Assess for typhlitis, abscess, perforation

If Central Line Concern

  • Line evaluation and culture

Meds – Initial (Give Within 60 Minutes)

Preferred Monotherapy

  • Cefepime 2 g IV q8h

OR

  • Piperacillin-Tazobactam 4.5 g IV q6h

If Septic Shock / ESBL History / Severe Abdominal Source

  • Meropenem 1 g IV q8h

Add Vancomycin ONLY If

  • Hemodynamic instability

  • Suspected CLABSI

  • Skin/soft tissue infection

  • Pneumonia

  • Known MRSA

  • Severe mucositis

Vancomycin

  • 15–20 mg/kg IV q8–12h

  • Pharmacy dosing

De-escalate at 48–72 hr if cultures negative for gram-positive infection.

Antifungal Therapy (Add If Fever >4–7 Days)

Candida Coverage

  • Fluconazole 400 mg IV/PO daily

Aspergillus Suspected

  • Voriconazole 6 mg/kg IV q12h × 2 doses

  • Then 4 mg/kg IV q12h

Alternative

  • Caspofungin 70 mg IV ×1

  • Then 50 mg IV daily

Growth Factor

Filgrastim (G-CSF)

  • 5 mcg/kg SQ daily

Consider if:

  • ANC <100

  • Expected neutropenia >7 days

  • Severe sepsis

  • High-risk malignancy

Continue Home Meds

  • Antiviral prophylaxis (acyclovir/valacyclovir)

  • Antifungal prophylaxis

  • Existing G-CSF regimen if already prescribed

Monitoring

  • Telemetry

  • Continuous pulse ox if unstable

  • Strict I&O

  • Daily weights

  • Vital signs q4h

Neutropenic Precautions

  • Private room if available

  • Strict hand hygiene

  • No fresh flowers/plants

  • Avoid sick visitors

  • Low microbial diet per institution policy

Consults

  • Oncology

  • Hematology

If Shock

  • ICU

If Typhlitis

  • General Surgery

If Fungal Infection

  • Infectious Disease

If Line Infection

  • PICC/Vascular Access Team

Central Line Removal

  • Candida bloodstream infection

  • MRSA bacteremia

  • Tunnel infection

  • Persistent gram-negative bacteremia despite therapy

VTE Prophylaxis

  • Enoxaparin 40 mg SQ daily

OR

  • Heparin 5000 units SQ q8h

If platelets adequate and no contraindication.

Therapy

  • PT/OT evaluate and treat

  • Ambulation TID

Discharge Criteria

  • Afebrile ≥48 hr

  • Hemodynamically stable

  • ANC ≥500 and recovering

  • Cultures addressed

  • Tolerating PO

Oral Step-Down (Low Risk)

  • Ciprofloxacin 500 mg PO BID
    PLUS

  • Amoxicillin-Clavulanate 875 mg PO BID

(Only if not on fluoroquinolone prophylaxis)

Red Flags

  • Fever + ANC <500 = antibiotics within 60 min

  • ANC <100 = highest mortality risk

  • Septic shock = ICU + Meropenem + Vancomycin

  • RLQ pain = CT A/P (typhlitis until proven otherwise)

  • Fever >7 days = CT chest + empiric antifungal

  • Candida or MRSA CLABSI = remove line immediately