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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Febrile neutropenia

Infectious diseases, microbiology and sexual health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Neutropenic sepsis

A patient receiving anticancer treatment with neutrophils at or below 0.5 × 10⁹/L and temperature above 38°C, or any clinically significant sepsis feature, has a time-critical emergency.

Action: Use ABCDE, obtain blood cultures and baseline tests immediately, and give the locally approved empirical intravenous antibiotic without waiting for the differential count, imaging or microbiology when sampling would cause delay. Escalate shock, hypoxaemia or organ dysfunction to critical care early.

Overview

Recognise infection despite attenuated inflammation, deliver immediate empirical antibacterial treatment, recover useful microbiology, and respond intelligently to instability, resistance risk and persistent fever.

Neutropenia removes a major cellular defence against bacteria and fungi. Cytotoxic treatment also injures oral and intestinal mucosa, while central venous devices breach skin and repeated healthcare contact selects resistant flora. Infection may therefore progress from endogenous gut organisms or a line with little pus, erythema or radiographic inflammation. Depth, duration and trajectory of neutropenia matter: an absolute neutrophil count below 0.1 × 10⁹/L for more than seven days creates particularly high bacterial and mould risk.

The first hour has two simultaneous goals: preserve diagnostic yield and deliver active therapy. Record the anticancer regimen, cycle day, prophylaxis, allergy phenotype, line type, previous cultures, recent antibiotics and overseas healthcare. Examine mouth, teeth, skin folds, perineum, line sites, lungs, abdomen and neurological state while avoiding rectal examination, suppositories and unnecessary mucosal trauma in profound neutropenia.

Aetiology

01

Endogenous bacterial flora

Enteric Gram-negative bacilli, streptococci and other colonising organisms cross chemotherapy-injured mucosa; antibacterial exposure can select resistant strains that later cause bloodstream infection.

02

Healthcare and device exposure

Central catheters, repeated admissions, procedures and broad antimicrobials create portals for staphylococci, enterococci, resistant Gram-negative organisms and Clostridioides difficile.

03

Prolonged immune deficit

Deep neutropenia lasting beyond a week, corticosteroids and haematological malignancy increase invasive Aspergillus, Candida and other opportunistic infection risk.

04

Non-infectious fever

Cancer, thrombosis, blood products and medicines can generate fever, but none safely excludes coincident infection during a high-risk neutropenic episode.

Pathophysiology

  1. 1
    Phagocyte failure

    Too few functioning neutrophils prevents effective containment and killing of extracellular bacteria and filamentous fungi, allowing a small inoculum to disseminate rapidly.

  2. 2
    Barrier disruption

    Mucositis and epithelial injury expose submucosal tissue and permit oral or intestinal organisms to enter lymphatics and blood without a discrete wound.

  3. 3
    Attenuated inflammatory signs

    Pus, erythema, consolidation and abscess formation depend partly on recruited neutrophils, so severe infection can initially produce sparse examination and imaging findings.

  4. 4
    Microbiome selection

    Fluoroquinolone prophylaxis and repeated broad therapy suppress susceptible flora while enriching resistant organisms, making earlier microbiology central to empirical selection.

  5. 5
    Immune-recovery inflammation

    Returning neutrophils may reveal or intensify inflammation around an established focus, changing symptoms and imaging despite microbiologically active treatment.

Clinical features and red flags

Fever or hypothermiaRed flag

A single temperature above 38°C meets the NICE temperature element; hypothermia, rigors or an unexplained temperature trend can be equally concerning in a profoundly immunosuppressed patient.

Muted focal inflammation

Odynophagia, dental pain, cough, diarrhoea, perianal discomfort or line tenderness may be the only local clue because neutropenia limits purulence and erythema.

Physiological deteriorationRed flag

New tachycardia, breathlessness, confusion, weakness, oliguria or poor perfusion warrants emergency treatment even before fever or the current neutrophil count is known.

Abdominal syndromeRed flag

Right-sided pain, distension, diarrhoea or bleeding during profound neutropenia suggests enterocolitis; peritonism or shock may indicate necrosis or perforation.

Prolonged-fever phenotypeRed flag

Fever continuing after four to seven days of appropriate antibacterials during expected prolonged neutropenia should trigger renewed source review and a risk-based invasive-fungal assessment.

Red flags requiring action

  • Hypotension, new confusion, tachypnoea, mottling, oliguria, rising lactate or a new oxygen requirement indicates high-risk sepsis even when fever is absent.
  • Severe abdominal pain, distension, diarrhoea, guarding or gastrointestinal bleeding may represent neutropenic enterocolitis, perforation or Clostridioides difficile infection.

Investigations

  1. 01
    Immediate blood culturesFirst step
    Why
    Recover bloodstream pathogens and distinguish peripheral from catheter-associated infection before antimicrobial exposure reduces yield.
    Interpretation and limitations
    Obtain at least one adequately filled peripheral set and paired cultures from relevant catheter lumens if this is immediately feasible. Label sites and times precisely; do not postpone the first antibiotic for difficult access.
  2. 02
    First-line severity panelFirst line
    Why
    Confirm cytopenias, detect organ dysfunction and provide baselines for antimicrobial dosing and sepsis reassessment.
    Interpretation and limitations
    Request FBC with differential, renal and liver profiles including albumin, CRP and lactate, with glucose, clotting and group-and-save when clinically indicated. A pending or temporarily normal neutrophil count does not justify delay.
  3. 03
    Syndrome-directed microbiology
    Why
    Identify respiratory, urinary, enteric, skin, viral or fungal causes without indiscriminate low-yield sampling.
    Interpretation and limitations
    Send urine culture when symptoms or catheter context support it, stool testing for significant diarrhoea, respiratory PCR and sputum when respiratory disease is present, and lesion aspirate or tissue rather than superficial swabs whenever possible.
  4. 04
    Targeted imaging

Differential diagnosis

01

Drug or infusion reaction

Temporal relation to chemotherapy, antibody infusion or a new medicine, with rash or bronchospasm, supports a reaction but blood cultures and sepsis assessment remain necessary.

02

Transfusion reaction

Fever, rigors, dyspnoea or hypotension during transfusion requires stopping the component, compatibility investigation and parallel assessment for bacterial contamination and unrelated sepsis.

03

Tumour fever

Persistent inflammatory fever can accompany malignancy, but it is a diagnosis of exclusion after infection, thrombosis and treatment toxicity have been assessed.

04

Thromboembolism

Catheter thrombosis or pulmonary embolism may cause fever, tachycardia and hypoxaemia; unilateral swelling, pleuritic symptoms and appropriate imaging help differentiate them.

05

Immune-mediated toxicity

Checkpoint-inhibitor pneumonitis, colitis, hepatitis or endocrinopathy can mimic infection and may coexist, requiring organ-directed tests before immunosuppression is escalated.

Management

01FIRST HOURTreat before certaintyFirst stepFever, sepsis physiology or concerning focal symptoms occur during or soon after anticancer treatment.+
  1. 1Perform ABCDE, establish intravenous access, measure lactate and assess shock, hypoxaemia, abdominal catastrophe and line or soft-tissue source.
  2. 2Take paired blood cultures and baseline bloods immediately while a second clinician prepares empirical treatment; do not await a neutrophil result.
  3. 3AlternativeGive piperacillin with tazobactam through the local neutropenic-sepsis protocol unless allergy, resistance history or a specific focus requires an approved alternative.
  4. 4Provide balanced fluid, oxygen and vasopressor or critical-care support according to physiology, with urgent source-control review where indicated.

Complications

01

Septic shock

Uncontained bacteraemia can produce vasoplegia, myocardial dysfunction, disseminated intravascular coagulation and multiorgan injury before a focal source becomes evident.

02

Neutropenic enterocolitis

Mucosal injury and microbial invasion cause caecal-predominant bowel-wall inflammation that may progress to necrosis, bleeding, perforation and polymicrobial sepsis.

03

Invasive fungal disease

Prolonged profound neutropenia permits angioinvasive mould infection or disseminated yeast disease, causing infarction, haemorrhage and lung, sinus, brain or other organ injury.

04

Catheter metastatic infection

Persistent catheter-related bacteraemia can seed heart valves, joints, bone, lungs or the eye, especially when an infected device remains in place.

05

Antimicrobial harm

Unnecessary breadth and duration increase renal injury, cytopenia, drug interactions, Clostridioides difficile infection and selection of organisms resistant to future rescue treatment.

Monitoring and follow-up

  • Repeat observations and NEWS2 according to acuity, with urine output, mental state, perfusion and oxygen requirement tracked more closely than temperature alone.
  • Review FBC, renal and liver profiles daily during acute treatment, recalculating antimicrobial doses when kidney function, weight or organ support changes.
  • Check blood-culture signals, identification and susceptibility at least daily and document the planned response to preliminary Gram stain as well as the final result.
  • Record the indication, start time and 24- to 48-hour review decision for every antimicrobial, including explicit stop or narrowing criteria.
  • For persistent fever, chart neutrophil duration, prophylaxis exposure, CT and biomarker results so antifungal decisions reflect pre-test probability rather than fever alone.
  • Before ambulatory care or discharge, confirm reliable oral absorption, transport, telephone access, responsible review team and instructions for immediate return with recurrent symptoms.

Special situations

Afebrile does not mean safe

Corticosteroids, antipyretics and profound immune failure may suppress temperature; new hypotension, confusion, abdominal pain or breathlessness deserves the same emergency response.

Line cultures need labels

Differential time to positivity is interpretable only when peripheral and lumen specimens have accurate source and collection-time labels and comparable blood volumes.

Neutrophil trajectory predicts risk

A count expected to recover tomorrow carries a different opportunistic risk from profound neutropenia expected to persist for weeks, even at the same measured value.

Fever can be non-infectious

Transfusion reactions, thrombosis, tumour fever, mucositis and drug reactions are genuine alternatives, but they are considered after immediate infection treatment in a high-risk presentation.

Recovery can unmask inflammation

Pulmonary infiltrates, abscess features or clinical inflammation may become more visible as neutrophils recover; apparent radiological worsening needs integrated clinical interpretation.

Common pitfalls

  1. 01

    Waiting for the FBC, chest imaging or consultant review before delivering the first active empirical antibiotic.

  2. 02

    Using a previous low-risk score to dismiss new physiological instability or a focal syndrome that requires admission and source control.

  3. 03

    Adding gentamicin or a glycopeptide by habit without a documented indication, review time and toxicity plan.

  4. 04

    Performing rectal examination, rectal temperature measurement or suppository administration during profound neutropenia when a safer assessment is available.

  5. 05

    Treating every persistent fever as resistant bacteria and repeatedly broadening antibacterials without CT, fungal assessment or review for a non-infectious cause.

  6. 06

    Assuming a central line must remain because access is difficult when persistent bacteraemia, tunnel infection or an unsafe organism makes removal part of source control.

Practice

Two practice questions

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Infectious diseases, microbiology and sexual healthOriginal SBA

Immediate febrile-neutropenia action

A patient eight days after cytotoxic chemotherapy has a temperature of 38.3°C, new rigors and a neutrophil count that is still pending. What is the best next step?

Choose one answer, then submit
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • Recommendations | Neutropenic sepsis: prevention and management in people with cancer | Guidance | NICE
  • Neutropenic sepsis | Quality standards | NICE
  • Piperacillin/Tazobactam 4 g/0.5 g powder for solution for infusion - Summary of Product Characteristics (SmPC) - (emc) | 100194
  • Start Smart - Then Focus: antimicrobial stewardship toolkit for inpatient care settings
  • British Society for Medical Mycology best practice recommendations for the diagnosis of serious fungal diseases

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
One framework cannot safely select every regimen. Local antibiograms, prior resistant isolates, organ function, immediate hypersensitivity and the suspected focus may override standard monotherapy. Microbiology review should convert broad empirical treatment into a documented plan: continue because instability persists, narrow to a recovered pathogen, change for an uncovered focus, or stop according to validated low-risk and clinical criteria.

Key points

  • Treat suspected neutropenic sepsis as an acute medical emergency; a normal temperature does not exclude dangerous infection when corticosteroids, antipyretics or profound immune failure blunt fever.
  • NICE uses neutrophils 0.5 × 10⁹/L or lower plus temperature above 38°C or another clinically significant sepsis feature in a patient receiving anticancer treatment.
  • Take peripheral blood cultures and, where feasible, a separate culture from every relevant central-line lumen before antibiotics, but never sacrifice prompt treatment to complete sampling.
  • Piperacillin with tazobactam is NICE-supported initial beta-lactam monotherapy when intravenous treatment is required, unless allergy, previous microbiology or local resistance makes it unsuitable.
  • Do not add an aminoglycoside or glycopeptide routinely; use additional cover for a defined clinical, microbiological or local-epidemiological indication.
  • Reassess physiology, source, cultures and antimicrobial exposure repeatedly; narrowing, oral switch or discharge depends on validated risk assessment and reliable follow-up rather than the temperature alone.
  • Persistent fever is a decision point, not an automatic diagnosis: repeat examination, seek an occult focus and assess invasive fungal risk before starting a mould-active agent.
  • The infectious-diseases emphasis is organism recovery, resistance-informed empirical choice and targeted escalation; chemotherapy scheduling and marrow-support decisions remain with acute oncology or haematology.
  • Pleuritic pain, haemoptysis, nasal eschar, focal neurology or fever persisting during broad antibacterial therapy raises concern for invasive mould disease.
  • Pain out of proportion, rapidly spreading erythema, bullae or crepitus requires immediate surgical review for necrotising soft-tissue infection.
  • A tunnelled-line exit-site change, rigors during line use or unequal paired-culture time to positivity may signal catheter-related bloodstream infection.
  • Previous colonisation with a carbapenemase producer, resistant Gram-negative isolate or recent overseas healthcare changes empirical cover and requires immediate microbiology ownership.
    • Why
    Locate pneumonia, enterocolitis, abscess, thrombosis or another deep focus that examination may underestimate.
    Interpretation and limitations
    Chest radiography is not routine without a clinical indication. Use CT chest for persistent respiratory concern or mould risk and contrast CT abdomen and pelvis for significant abdominal features, balancing instability and renal function.
  • 05
    Invasive-fungal work-up
    Why
    Support an evidence-led pre-emptive or targeted antifungal strategy when neutropenia is prolonged or fever persists.
    Interpretation and limitations
    Combine high-resolution CT, serum galactomannan where locally validated, and bronchoalveolar lavage or tissue for microscopy, culture, molecular tests and histology. No single biomarker is a gold-standard exclusion test.
  • 06
    Validated risk assessment
    Why
    Estimate complication risk after initial stabilisation and support safe inpatient, oral-switch or ambulatory decisions.
    Interpretation and limitations
    Apply the locally adopted tool, commonly MASCC and sometimes CISNE in stable solid-tumour patients, within the clinical pathway. A favourable score cannot override organ dysfunction, an uncontrolled focus or unreliable follow-up.
    • 02
    RESISTANCE CHECKIndividualise empirical coverPrevious resistant organisms, severe beta-lactam allergy, recent broad antibiotics, overseas healthcare or septic shock makes standard monotherapy unreliable.
    +
    1. 1Retrieve previous microbiology and allergy documentation rather than accepting an unverified label or relying only on the current admission history.
    2. 2Contact microbiology immediately and use the hospital pathway for the specific resistance or allergy phenotype, with renal and weight adjustment.
    3. 3Add Gram-positive coverage only for a defined indication such as suspected catheter infection, severe skin disease, resistant Gram-positive history or haemodynamic instability.
    4. 4Record the indication and review point for every added agent so combination therapy does not persist after cultures and clinical response permit narrowing.
    03DAILY REVIEWFocus and de-escalateEscalationInitial resuscitation is complete and microbiology, imaging and clinical trajectory become available.+
    1. 1Re-examine mouth, line sites, lungs, skin, perineal region externally and abdomen; review every culture, susceptibility result and new symptom.
    2. 2Narrow to the recovered pathogen and focus when safe, and arrange drainage, line management or surgical control rather than prolonging unnecessary breadth.
    3. 3After at least 48 hours, consider oral switch or ambulatory care only when the validated score, physiology, absorption, social support and rapid-return arrangements all support low risk.
    4. 4Do not continue empirical therapy solely until neutrophil recovery in a clinically well, reassessed low-risk patient if the local evidence-based stopping pathway permits cessation.
    04PERSISTENT FEVERSearch before escalatingEscalationFever continues despite an apparently active antibacterial regimen or recurs during prolonged profound neutropenia.+
    1. 1Confirm dosing, administration, cultures and susceptibility, repeat a full examination and seek occult line, lung, sinus, abdominal, skin or drug-related causes.
    2. 2Repeat cultures during new rigors or deterioration and obtain CT chest promptly when invasive mould disease is plausible, even if chest radiography is unrevealing.
    3. 3Use fungal biomarkers and respiratory or tissue sampling to support a pre-emptive strategy where the local service can deliver rapid testing.
    4. 4Start locally approved mould-active therapy with haematology and infection specialists when high-risk persistent fever, imaging or microbiology supports it; account for existing prophylaxis and interactions.
    05SOURCE CONTROLRemove the anatomical driverImaging, examination or microbiology identifies an infected device, collection, necrotic tissue or perforated viscus.+
    1. 1Involve the relevant procedural team early and coordinate platelet support and antimicrobial timing with haematology when intervention carries bleeding risk.
    2. 2Remove a catheter promptly for tunnel infection, persistent bacteraemia, haemodynamic instability or organisms for which retention is unsafe, following specialist assessment.
    3. 3Avoid bedside incision or rectal instrumentation without senior planning in profound cytopenia, but do not allow cytopenia alone to defer life-saving surgery.
    4. 4Send deep specimens at intervention and revise therapy from operative findings, culture and histology.
    Key medicines and prescribing safety4 treatments · regimens, roles and cautions+
    NICE-supported first-line empirical beta-lactam monotherapy when intravenous treatment is required and no patient-specific or microbiological contraindication exists.

    Piperacillin with tazobactam

    Give 4.5 g intravenously every 6 hours for febrile neutropenia in an adult with normal renal function, using the stocked product instructions and local infusion policy.

    Check the immediate-allergy phenotype, renal function, sodium load and previous resistant isolates; adjust the interval in renal impairment and review for cytopenia, hepatic effects and Clostridioides difficile infection.

    Provides immediate Gram-negative and other required cover when piperacillin with tazobactam cannot be given safely.

    Severe beta-lactam-allergy regimen

    Use the hospital's named severe immediate beta-lactam-allergy neutropenic-sepsis protocol, selected urgently with microbiology from the allergy phenotype, previous isolates, renal function and suspected source.

    There is no single nationally correct substitute; aztreonam-based combinations may leave important gaps, while carbapenem cross-reactivity and glycopeptide need require individual assessment.

    Additional resistant Gram-positive cover for selected catheter, skin, culture-proven or haemodynamically unstable presentations rather than routine initial therapy.

    Vancomycin or teicoplanin

    Use the locally specified weight- and renal-function-based intravenous loading regimen, then adjust maintenance to measured concentrations and the confirmed organism; do not add empirically without an indication.

    Monitor kidney function and concentrations, minimise concurrent nephrotoxins and stop promptly when cultures and source assessment do not support continued glycopeptide exposure.

    Empirical, pre-emptive or targeted treatment for high-risk persistent fever or evidence of invasive fungal disease, not an automatic addition for every fever.

    Mould-active antifungal therapy

    Use the haematology infection pathway for the selected agent and dose after accounting for prophylaxis, imaging, organ function, weight and interacting anticancer or immunosuppressive medicines.

    Azoles have major CYP interactions and variable exposure; amphotericin formulations can injure kidneys and electrolytes, while echinocandins do not provide equivalent coverage for every mould syndrome.