Neutropenic sepsis

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Neutropenic sepsis is infection with an impaired inflammatory defence during or after anticancer treatment. The risk is not captured by one count: a neutrophil nadir below 0.5 × 10^9/L, especially below 0.1 × 10^9/L, becomes more dangerous as duration increases, but mucositis, central access, tumour obstruction, corticosteroids, transplantation and organ dysfunction can make a patient high risk before the nadir is documented. Gut organisms, skin flora, line pathogens and environmental moulds exploit broken barriers. Previous antibiotics and colonisation determine whether the initial ecology is likely to include resistance.

Presentation may be striking or almost silent. Fever and rigors are common, but malaise, new confusion, diarrhoea, mouth pain, perianal discomfort, line tenderness or an unexplained change in blood pressure may be the only warning. Neutrophils generate pus, erythema and much of radiographic consolidation; their absence reduces familiar signs rather than reducing microbial threat. Corticosteroids and antipyretics further suppress fever. Triage must therefore ask about recent systemic treatment and the predicted nadir whenever an oncology patient feels unwell.

The first hour is a parallel emergency pathway. Establish physiology, take blood cultures from a peripheral site and each relevant line lumen if this can be done promptly, measure lactate, blood count, renal and hepatic function and inspect likely portals. Give empirical intravenous treatment immediately. NICE recommends piperacillin/tazobactam monotherapy unless allergy, previous microbiology, colonisation, local resistance or a specific source requires a different regimen. Routine aminoglycoside exposes kidneys and hearing without standard benefit; routine glycopeptide for the mere presence of a line also adds toxicity and resistance pressure.

After the first dose, refine rather than relax. Repeat physiology and lactate, control an infected line, abscess or obstruction, and review cultures, organ function and expected neutropenia. A validated risk tool can contribute to disposition, but never overrules shock, hypoxia, significant comorbidity, uncontrolled symptoms, unreliable support or inability to absorb oral medicine. Persistent or recurrent fever with prolonged neutropenia changes the probability: obtain early CT and fungal biomarkers according to the haematology or oncology pathway and choose mould-active therapy with microbiology, considering existing prophylaxis and drug interactions.

Key points

Suspect neutropenic sepsis in any unwell person receiving or recently receiving systemic anticancer treatment, even when fever and focal inflammatory signs are absent.
NICE defines it as neutrophils 0.5 × 10^9/L or lower with temperature above 38°C or other clinically significant sepsis features, but treatment begins before the laboratory result when suspicion is credible.
First-line assessment is simultaneous ABCDE, full observations, lactate, FBC, renal and liver tests and peripheral plus relevant line cultures; sampling must not postpone antibiotic delivery.
First-line empirical therapy is intravenous piperacillin/tazobactam monotherapy under NICE when allergy, prior resistant organisms and local microbiology do not require an alternative.
Do not add an aminoglycoside routinely and do not add a glycopeptide solely because a central line is present; each addition needs a defined microbiological or clinical indication.
Search mouth, skin, line, lungs, abdomen and perianal area gently, but avoid digital rectal examination, suppositories and unnecessary rectal instrumentation during profound neutropenia.
Use validated risk assessment only after immediate treatment and physiological review; ambulatory care also requires stable organ function, oral absorption, support, transport and rapid 24-hour return.
Persistent fever during prolonged neutropenia needs CT-based fungal assessment and specialist therapy planning rather than repeated unstructured antibacterial escalation.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Myelosuppressive anticancer treatment

Cytotoxic, targeted and cellular therapies can reduce neutrophil production; depth, speed and predicted duration of the regimen-specific nadir determine infectious risk.

Barrier injury

Oral and intestinal mucositis, tumour ulceration, surgery and central venous devices allow commensal or healthcare-associated organisms to enter tissue and blood.

Extended immune dysfunction

Haematological malignancy, transplantation, corticosteroids and previous broad antimicrobials add lymphocyte, phagocyte and microbiome defects beyond the absolute neutrophil count.

Resistant and fungal selection

Prior prophylaxis, admissions, colonisation and prolonged antibacterial exposure favour resistant bacteria, Clostridioides difficile, Candida and invasive mould infection.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Impaired innate containment
Too few functional neutrophils reach infected tissue, reducing phagocytosis, pus and visible inflammation while microbial replication and invasion continue.
2
Translocation into blood
Damaged mucosa or an intravascular-device biofilm gives organisms direct access to the circulation, permitting bacteraemia and endotoxin-mediated vasodilatation.
3
Muted localisation
Consolidation, erythema, guarding and fever may be absent because the inflammatory response creates many of the signs normally used to locate infection.
4
Shock and organ injury
Microbial products and dysregulated host signalling cause endothelial leak, maldistributed flow and cellular dysfunction, progressing rapidly to kidney, lung, brain and coagulation failure.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Fever at the nadir

A temperature above 38°C during a predicted low-count window is the classic presentation and activates immediate assessment before the count returns.

Afebrile physiological changeRed flag

Rigors, hypotension, tachypnoea, confusion, oliguria or abrupt functional decline after treatment is compatible with neutropenic sepsis despite normal temperature.

Mucosal source

Odynophagia, oral ulceration, abdominal discomfort or diarrhoea may identify chemotherapy-damaged mucosa as the portal while visible inflammation remains modest.

Device-associated infection

Line-site pain, tunnel tenderness, discharge or culture growth may indicate catheter infection, but a normal external site cannot exclude intraluminal bacteraemia.

Enterocolitis patternRed flag

Fever with right-sided or diffuse abdominal pain, distension, diarrhoea or bleeding during profound neutropenia raises bowel-wall inflammation, necrosis and perforation.

Fungal trajectoryRed flag

Ongoing fever, pleuritic pain, haemoptysis, sinus symptoms or CT nodules after several antibacterial days during prolonged neutropenia suggests invasive mould disease.

Red flags requiring action

Hypotension, rising lactate, mottling, oliguria, confusion, hypoxaemia or respiratory fatigue indicates organ dysfunction and needs senior resuscitation and critical-care review.
A normal temperature does not exclude neutropenic sepsis when corticosteroids, antipyretics or profound immune suppression blunt fever.
Severe abdominal pain, distension or diarrhoea during neutropenia raises neutropenic enterocolitis, perforation and Clostridioides difficile infection.
Perianal pain, line tenderness, oral ulceration or subtle skin change can be the only local clue; avoid rectal examination and instrumentation.
Persistent or recurrent fever during prolonged profound neutropenia despite antibacterial treatment raises invasive fungal infection and requires a new diagnostic strategy.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line observations and lactateFirst stepFirst line
Why
Identify organ dysfunction and establish the urgency and response to resuscitation.
Interpretation and limitations
Use full repeated observations, mental state, perfusion and urine output; normal lactate does not exclude serious early infection, while a rising value demands escalation.
02
FBC with differential
Why
Confirm neutropenia and assess accompanying anaemia and thrombocytopenia.
Interpretation and limitations
Do not await the result before empirical treatment. Record depth and predicted duration because these change disposition and fungal risk.
03
Peripheral and central-line blood cultures
Why
Recover bloodstream organisms and compare possible catheter sources.
Interpretation and limitations
Sample every relevant line lumen plus a peripheral set before antibiotics only when immediately achievable; difficult access must not delay the first dose.
04
Renal, liver, glucose and coagulation profile
Why
Grade organ injury and select safe antimicrobial and procedural doses.
Interpretation and limitations
Recalculate dosing as kidney or liver function changes; hypoglycaemia, coagulopathy or acute kidney injury increases severity and may reveal another emergency.
05
Source-directed cultures and imaging
Why
Identify pulmonary, urinary, gastrointestinal, skin, line or obstructed infection requiring targeted treatment.
Interpretation and limitations
Collect urine, respiratory or stool specimens from symptoms; obtain chest imaging for respiratory features and cross-sectional imaging when abdominal disease or an occult source is plausible.
06
CT chest and fungal biomarkers
Why
Detect invasive mould disease during persistent fever with prolonged profound neutropenia.
Interpretation and limitations
CT is more sensitive than a plain radiograph; galactomannan or beta-D-glucan depends on host, prophylaxis and assay and must be interpreted with imaging and microbiology.
07
Validated risk assessment
Why
Support inpatient, step-down or ambulatory decisions after initial stabilisation.
Interpretation and limitations
Use a locally approved tool such as MASCC with experienced judgement; low numerical risk does not overcome organ dysfunction, poor support or unreliable follow-up.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Treatment infusion reaction

Drug fever, hypersensitivity and cytokine-release syndrome can cause fever, hypotension or hypoxia, but infection is covered immediately while timing and syndrome-specific features are assessed.

Cancer-related fever

Tumour inflammation can produce recurrent temperature without infection, but this remains a diagnosis of exclusion after urgent empirical treatment in a neutropenic patient.

Thromboembolic disease

Pulmonary embolism or catheter thrombosis can cause tachycardia, hypoxaemia and fever and may coexist with infection in an active cancer patient.

Adrenal or metabolic crisis

Adrenal insufficiency, tumour lysis and severe electrolyte disturbance can mimic septic collapse; bedside glucose, renal and metabolic testing runs in parallel.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01First hourCulture promptly and treat immediatelyFirst stepRecent anticancer treatment accompanies fever, rigors or clinically important sepsis features.

1Use ABCDE, monitoring and intravenous access; obtain lactate, FBC, renal and liver tests and peripheral plus line cultures without allowing difficult sampling to delay treatment.
2Give the local empirical intravenous regimen immediately, using piperacillin/tazobactam monotherapy when NICE and patient microbiology support it.
3EscalationResuscitate hypoperfusion with repeated assessment, give oxygen for hypoxaemia and escalate shock, respiratory failure or altered consciousness to critical care while searching for source.

02Source controlFind the quiet focusInitial treatment has started and examination or results suggest a local source.

1Re-examine mouth, skin, line, lungs and abdomen and inspect the perianal region externally; avoid digital rectal examination and unnecessary mucosal procedures.
2Drain an abscess, relieve urinary or biliary obstruction and remove an infected device when indicated, balancing thrombocytopenia and access needs with the procedural team.
3Tailor antimicrobials to source and cultures, adding resistant Gram-positive or Gram-negative coverage only for a documented indication and formal review point.

03DispositionConstruct a supported low-risk pathwayThe patient responds to initial treatment and outpatient or step-down care is being considered.

1Apply the approved risk tool after confirming stable observations, organ function, symptom control and no high-risk focus, prolonged neutropenia or resistant-organism concern.
2Confirm reliable oral absorption, cognition, home support, transport, telephone access, proximity and a 24-hour route that can reassess and readmit immediately.
3Provide exact oral regimen and duration review, thermometer and written return triggers; arrange early clinical contact and retain ownership of culture results.

04Persistent feverReframe the differentialFever persists or recurs despite appropriate broad antibacterial treatment during prolonged neutropenia.

1Repeat focused cultures and examination, review line, prophylaxis and drug fever, and obtain early CT chest with fungal biomarkers under the high-risk pathway.
2Discuss pre-emptive or empirical mould-active treatment with infection and oncology specialists, selecting around prior azole exposure, organ function and anticancer interactions.
3Avoid stacking antibacterial drugs without a new hypothesis; document the infection endpoint, neutrophil recovery plan and criteria for tissue sampling or treatment change.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

NICE first-line empirical intravenous monotherapy when allergy, previous resistant organisms and local microbiology do not dictate another regimen.

Piperacillin/tazobactam

With normal renal function, give piperacillin 4 g with tazobactam 0.5 g intravenously every 6 hours for adult neutropenic fever, using the current local infusion policy and adjusting dose or interval for renal function.

Check the exact beta-lactam allergy, kidney function, sodium load and previous cultures; monitor cytopenia, liver tests, electrolyte change, rash and Clostridioides difficile and review daily for narrowing.

Preserves timely broad Gram-negative and other relevant coverage when standard piperacillin/tazobactam is unsafe or predictably inactive.

Alternative empirical antibacterial regimen

For immediate severe beta-lactam allergy or known resistant colonisation, give the locally specified intravenous alternative at full sepsis doses immediately, with microbiology-directed renal and weight adjustment.

The alternative is patient- and ecology-specific. Avoid routine aminoglycoside or glycopeptide exposure; monitor renal, auditory, marrow, neurological, QT and interaction risks of the chosen combination.

Treats probable or proven invasive mould disease and selected persistent-fever presentations during prolonged profound neutropenia.

Mould-active antifungal therapy

Use the product-specific loading and maintenance regimen chosen by infection and oncology specialists from CT pattern, prophylaxis, likely organism, body weight and hepatic or renal function.

Triazoles have major CYP interactions and QT effects, while amphotericin formulations can injure kidney and waste potassium or magnesium; obtain diagnostic material when safe without postponing unstable-patient treatment.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Septic shock

Progressive vasodilatation, capillary leak and myocardial dysfunction can require vasopressors, ventilation and multi-organ support before a culture or anatomical source becomes available.

Neutropenic enterocolitis

Chemotherapy injury and microbial invasion of caecal or colonic wall cause pain, fever, diarrhoea, necrosis, bleeding and possible perforation.

Invasive fungal disease

Prolonged profound neutropenia permits angioinvasive mould infection of lung or sinus and disseminated disease, sometimes with an initially normal chest radiograph.

Treatment interruption

Critical infection, organ injury and prolonged marrow suppression can delay curative therapy and require secondary prophylaxis or regimen and growth-factor review.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Repeat full observations, perfusion, mental state and urine output frequently until stable; recheck lactate after resuscitation when initially raised or physiology worsens.
Review blood and source cultures every day and communicate positive resistant or catheter-associated results immediately to the team holding clinical responsibility.
Trend neutrophils, platelets, kidney and liver function and adjust antimicrobial doses without reducing exposure below the effective sepsis regimen.
Re-examine for evolving mouth, skin, lung, abdominal, line and perianal signs because localisation may appear during neutrophil recovery.
At 24 to 48 hours, document response, source, antimicrobial indication, spectrum, route and next review; remove unnecessary duplicate or toxic agents.
Before ambulatory care or discharge, confirm validated risk, support, absorption, emergency access, early review and ownership of every outstanding culture or scan.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

No fever is still sepsis

Profound neutropenia, steroids and antipyretics can suppress temperature, so physiological deterioration after treatment activates the same urgent pathway.

A line needs evidence

Central access increases risk but does not alone justify glycopeptide; site findings, haemodynamics, culture and resistant history determine targeted addition.

Low risk needs infrastructure

A favourable score is only one component; rapid return, oral absorption, reliable support and active oncology follow-up make ambulatory care safe.

Count recovery can reveal disease

Pulmonary infiltrates and abscess signs may become more visible as neutrophils return, so apparent new inflammation may localise a pre-existing infection.

Persistent fever changes strategy

When prolonged neutropenia continues, fungal imaging and microbiology add more value than reflexively broadening antibacterial therapy again.

11Common pitfallsFrequent interpretation and management errors.

01
Waiting for the absolute neutrophil count or chest radiograph before giving empirical antibiotics.
02
Excluding infection because temperature, CRP, pus or local tenderness is absent.
03
Adding an aminoglycoside routinely to every first-line regimen.
04
Adding a glycopeptide solely because a central venous catheter exists.
05
Performing digital rectal examination, suppository use or avoidable rectal instrumentation during profound neutropenia.
06
Declaring outpatient suitability from a risk score without checking organ function, absorption, support and rapid access.
07
Responding to prolonged fever by layering antibiotics without CT-based fungal reassessment.