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← Infectious diseases, microbiology and sexual health indexChapter sections
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.

Central-line infection

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

RapidFull
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Line-associated sepsis or metastatic infection

Shock, rigors during infusion, purulent tunnel infection, persistent bacteraemia, endocarditis signs or new focal pain can indicate a central-line source with rapidly spreading infection.

Action: Stop non-essential infusion, use ABCDE, obtain paired peripheral and line cultures rapidly, begin locally approved intravenous therapy and arrange urgent line removal and source assessment without delaying treatment for a deteriorating patient.

Overview

Recognise catheter-related bloodstream infection, obtain paired cultures correctly, distinguish local from systemic disease and decide promptly between line removal and carefully selected salvage.

A central-line infection may involve the exit site, subcutaneous tunnel, implanted-port pocket, catheter lumen, adherent thrombus or bloodstream. Catheter-related bloodstream infection is supported when microbiology links blood growth temporally or quantitatively to the device and no more plausible source exists.

Skin organisms enter at insertion or along the external surface, while hub contamination spreads down the lumen during repeated access. Staphylococci are common; Gram-negative organisms and Candida become more likely with critical illness, parenteral nutrition, femoral access or prolonged antimicrobial exposure.

A single positive culture with common skin flora requires careful interpretation, but false reassurance is dangerous in immunosuppressed or prosthetic-material patients. Conversely, unnecessary removal of essential dialysis or nutrition access also causes harm.

Management therefore combines accurate paired sampling, immediate treatment of sepsis, organism-specific assessment and decisive removal when cure with retained material is unlikely. Line salvage is a narrow specialist strategy, not a default.

Aetiology

01

Extraluminal migration

Skin flora track along the catheter surface after insertion, particularly during the early period before the tract stabilises.

02

Hub contamination

Repeated access introduces organisms into the lumen, where they adhere and proliferate during long-term catheter use.

03

Contaminated infusate

Rare intrinsic or preparation contamination exposes multiple patients or lumens to Gram-negative organisms or fungi. in susceptible exposed adults.

04

Haematogenous seeding

Bacteraemia from another focus colonises the catheter, so apparent line infection may actually be secondary. in susceptible exposed adults.

Pathophysiology

  1. 1
    Surface conditioning

    Plasma proteins coat catheter polymer and create binding sites for staphylococci, Candida and other organisms. during active invasive disease.

  2. 2
    Biofilm formation

    Microbes produce extracellular matrix within the lumen or outer surface, reducing immune clearance and antimicrobial killing.

  3. 3
    Continuous bloodstream shedding

    Biofilm releases organisms during infusion and catheter manipulation, causing rigors, bacteraemia and systemic inflammation. during active invasive disease.

  4. 4
    Thrombus interaction

    Fibrin sheath and venous thrombus provide additional protected substrate and may become a persistent infected focus.

Clinical features and red flags

Infusion-related rigorsRed flag

Fever, rigors or hypotension beginning during flushing or infusion strongly suggests intraluminal contamination but still requires paired cultures.

Exit-site infection

Local erythema, tenderness or purulent discharge within the skin entry area may remain superficial or accompany bloodstream infection.

Tunnel or pocket infectionRed flag

Tenderness, induration, erythema or fluctuance along a tunnel or over an implanted reservoir indicates deep device involvement.

Unexplained bacteraemiaRed flag

Bloodstream infection without urinary, respiratory, abdominal or other source should prompt review of every vascular device and access episode.

Septic thrombophlebitisRed flag

Persistent fever with ipsilateral neck, chest or arm swelling suggests infected venous thrombus around the catheter.

Disseminated infectionRed flag

New murmur, visual symptoms, spinal pain, joint pain or embolic features indicate endocardial, ocular, bone or joint seeding.

Red flags requiring action

  • Hypotension, altered mental state, oliguria or raised lactate after line access requires immediate sepsis management.
  • Purulence, tunnel tenderness, port-pocket inflammation or skin necrosis usually requires catheter removal rather than salvage.

Investigations

  1. 01
    Paired peripheral and catheter blood culturesFirst step
    Why
    Compare organism growth from equal-volume samples collected at nearly the same time before antibiotics.
    Interpretation and limitations
    Growth from the line more than two hours before the peripheral bottle supports catheter-related infection; identical organisms strengthen attribution.
  2. 02
    Cultures from separate lumens
    Why
    Identify a colonised lumen when a multi-lumen catheter is present and removal is not immediate.
    Interpretation and limitations
    Label exact lumen and time. Drawing only from the line cannot distinguish true bloodstream infection from intraluminal colonisation.
  3. 03
    Catheter-tip culture after removal
    Why
    Demonstrate colonisation of the removed distal catheter segment using a validated laboratory method.
    Interpretation and limitations
    Send only after removal and interpret alongside peripheral cultures; a positive tip alone does not prove systemic infection.
  4. 04
    Full blood count, CRP, renal, liver and lactate
    Why
    Assess physiological severity, organ dysfunction and safe antimicrobial dosing.
    Interpretation and limitations
    Markers support trajectory but do not localise the source; thrombocytopenia or organ injury escalates sepsis care.

Differential diagnosis

01

Infusion reaction

Medication or blood-product reactions cause fever and hypotension during infusion but lack concordant cultures and local catheter evidence.

02

Alternative sepsis source

Pneumonia, urinary, abdominal and wound infections can coincide with a central line and should be actively assessed.

03

Sterile thrombophlebitis

Catheter-associated venous thrombosis causes pain and swelling without microbial growth, though secondary infection can develop. on focused clinical assessment.

04

Contact dermatitis

Dressing or antiseptic allergy causes pruritic geometric erythema without purulence, tunnel tenderness or bloodstream infection. on focused clinical assessment.

05

Contaminated blood culture

A single bottle with common skin flora may reflect collection contamination, distinguished by repeat paired cultures and clinical context.

Management

01SAMPLEPreserve diagnostic yieldFirst stepLine infection is suspected and the adult is stable enough for cultures before antimicrobials.+
  1. 1Pause non-essential infusions, disinfect hubs correctly and take equal-volume peripheral and catheter blood-culture sets at nearly the same time.
  2. 2Label peripheral site, every sampled lumen, exact collection time and recent antimicrobial exposure before transport.
  3. 3AlternativeInspect and document exit, tunnel and pocket findings; seek alternative sources through history and examination.
  4. 4Retain the line temporarily only when no mandatory removal criterion exists and there is a documented review time.
02SEPSISTreat unstable catheter infectionShock, organ dysfunction or rapidly progressive systemic illness is present.+
  1. 1

Complications

01

Septic shock

High bloodstream inoculum produces vasodilatation, capillary leak, myocardial dysfunction and progressive organ injury. without timely definitive management.

02

Endocarditis

Sustained bacteraemia seeds native or prosthetic valves, especially with S aureus, enterococci or intracardiac material. without timely definitive management.

03

Septic thrombosis

Infected clot around the catheter sustains fever and embolic risk after simple catheter removal. without timely definitive management.

04

Metastatic infection

Bloodstream spread causes vertebral osteomyelitis, septic arthritis, ocular infection, splenic focus or other abscess. without timely definitive management.

05

Loss of vascular access

Repeated infection and thrombosis exhaust veins needed for dialysis, nutrition, chemotherapy or long-term treatment. without timely definitive management.

Monitoring and follow-up

  • Record temperature, haemodynamics, infusion-related symptoms and exit, tunnel or pocket appearance at least daily.
  • Repeat peripheral cultures every 24 to 48 hours until documented clearance.
  • Review the need for every vascular catheter daily and remove unnecessary devices promptly.
  • Monitor renal, hepatic and blood-count toxicity and any required antimicrobial serum exposure.
  • Examine for new murmur, embolic signs, visual symptoms, spinal pain, hot joint and limb swelling.
  • After removal check the site for bleeding, retained fragment, worsening cellulitis and adequacy of alternative access.
  • For salvage, schedule an early failure decision and surveillance cultures after treatment rather than waiting for clinical relapse.

Special situations

Volume affects comparison

Differential time to positivity is meaningful only when line and peripheral bottles receive comparable blood volume and reach incubation together.

A positive tip is contextual

Catheter colonisation without matching peripheral bloodstream growth may not explain systemic illness and should not trigger prolonged therapy automatically.

Exchange can preserve infection

Passing a new catheter over a guidewire through an infected tract risks transferring organisms onto fresh material.

Coagulase-negative is not always trivial

Repeated concordant growth in a prosthetic-material or immunocompromised patient may represent genuine biofilm bloodstream infection.

Candida favours removal

Fungal adherence and dissemination make retained catheter cure unreliable, so source control and specialist complication assessment are central.

Clearance starts the clock

Duration for significant bloodstream infection is anchored to effective therapy, documented negative cultures and complication status, not the first fever.

Common pitfalls

  1. 01

    Do not collect cultures only through the suspected line when a peripheral sample is feasible.

  2. 02

    Do not compare differential positivity from unequal, poorly timed blood volumes.

  3. 03

    Do not attempt salvage for pocket, tunnel, S aureus, Candida or persistent infection.

  4. 04

    Do not send routine catheter-tip cultures from a line removed for non-infective reasons.

  5. 05

    Do not call repeated matching skin-flora cultures contamination without clinical assessment.

  6. 06

    Do not replace infected access through the same contaminated tract unless an emergency specialist strategy requires it.

Practice

Two practice questions

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Question 1 of 2
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Infectious diseases, microbiology and sexual healthOriginal SBA

Paired culture interpretation

Equal-volume blood cultures are drawn simultaneously from a central line and a peripheral vein. The line culture flags positive three hours earlier with the same organism. What does this support?

Choose one answer, then submit
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Sources and review status4 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.

  • NICE CG139 Healthcare-associated infections: prevention and control in primary and community care
  • epic3 National Evidence-Based Guidelines for Preventing Healthcare-Associated Infections in NHS Hospitals in England
  • Clinical Practice Guidelines for the Diagnosis and Management of Intravascular Catheter-Related Infection
  • NICE NG253 Suspected sepsis in people aged 16 or over

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

Key points

  • Check line type, insertion date, lumens, indication, recent manipulation, parenteral nutrition, dialysis use and whether alternative access is possible.
  • Inspect the exit site, subcutaneous tunnel and implanted-port pocket for erythema, tenderness, discharge, erosion and fluctuance.
  • In a stable adult collect equal-volume paired blood cultures from a peripheral vein and each relevant catheter lumen before antibiotics.
  • A catheter culture becoming positive more than two hours before the paired peripheral sample supports a catheter source when sampling and incubation are comparable.
  • Do not culture a catheter tip unless the line is removed; send the distal segment using the laboratory method.
  • Remove the catheter promptly for severe sepsis, tunnel or pocket infection, S aureus, Candida, persistent bacteraemia or complicated infection.
  • Selected uncomplicated coagulase-negative staphylococcal infection in essential long-term access may be salvaged only with systemic therapy plus a protocolised antimicrobial lock.
  • Daily necessity review and aseptic insertion and access practices prevent more infections than routine prophylactic antibiotics.
Staphylococcus aureus, Candida or persistent bloodstream growth carries high risk of endocarditis and metastatic infection.
  • Positive cultures continuing beyond 48 to 72 hours of active therapy suggest retained infected catheter, thrombus or deep focus.
  • New murmur, conduction change, embolic event, back pain or hot joint demands targeted assessment for dissemination.
  • Painful arm or neck swelling with bacteraemia may indicate septic catheter-associated thrombosis.
    • 05
    Echocardiography
    Why
    Assess endocarditis when S aureus, enterococci, Candida, persistent bacteraemia, intracardiac prosthesis or clinical signs are present.
    Interpretation and limitations
    TTE is initial, but TOE is required when probability remains high or intracardiac material limits sensitivity.
  • 06
    Venous ultrasound or contrast CT
    Why
    Detect catheter-associated thrombosis, tunnel collection or another deep complication.
    Interpretation and limitations
    Use ultrasound for accessible veins and CT for central veins or thoracic extension; infected thrombus prolongs therapy and requires source-control planning.
  • 07
    Ophthalmic and focal imaging
    Why
    Investigate visual complaints, back pain, hot joint or other symptoms suggesting haematogenous spread.
    Interpretation and limitations
    Target imaging to symptoms; Candida bloodstream infection requires specialist ocular assessment according to current local practice.
    • Use ABCDE, measure lactate, obtain cultures without avoidable delay and provide physiology-guided oxygen, fluid and vasopressor support.
  • 2Begin the local intravenous regimen covering likely resistant Gram-positive and relevant Gram-negative organisms, adjusted for allergy and renal function.
  • 3AlternativeRemove the suspected line promptly after securing safe alternative access, particularly with purulence, tunnel disease or uncontrolled physiology.
  • 4Culture the tip after removal and search for thrombosis, endocarditis and metastatic infection when cultures or symptoms indicate.
    • 03REMOVEUse organism and anatomy to decideCultures identify S aureus, Candida, difficult Gram-negative infection, persistent growth or a deep catheter complication.+
    1. 1Remove the entire catheter or port system and drain any pocket or tunnel collection rather than exchanging through infected tissue.
    2. 2Repeat peripheral cultures every 24 to 48 hours until clearance and confirm that fever and organ dysfunction resolve.
    3. 3Evaluate for endocarditis, septic thrombosis and metastatic foci; these convert a short uncomplicated episode into prolonged treatment.
    4. 4Narrow therapy to susceptibility and define duration from culture clearance and adequate source control with infection specialists.
    04SALVAGEProtect essential long-term access selectivelyAn uncomplicated low-virulence infection affects irreplaceable access and none of the mandatory removal features is present.+
    1. 1Confirm organism and absence of tunnel, pocket, thrombus, endocardial or metastatic infection before attempting retention.
    2. 2Give systemic directed therapy plus a compatible antimicrobial-lock protocol to every colonised lumen under microbiology supervision.
    3. 3Repeat cultures early; remove the catheter if fever persists, cultures remain positive or the same organism recurs.
    4. 4Document that salvage preserves access but carries relapse risk and arrange close outpatient culture and site review.
    Key medicines and prescribing safety4 treatments · regimens, roles and cautions+
    Provides immediate treatment during unstable catheter-associated sepsis before organism identification.

    Empirical severe line-infection regimen

    Give the locally approved intravenous regimen after paired cultures, covering likely resistant Gram-positive organisms and adding Gram-negative activity according to shock, neutropenia, femoral access and local epidemiology.

    Base loading and maintenance on weight and renal function; review recent isolates, immediate beta-lactam allergy and drug concentrations where required.

    Provides preferred targeted beta-lactam treatment after line removal and susceptibility confirmation.

    Flucloxacillin for MSSA

    Give 2 g intravenously every four hours for confirmed methicillin-susceptible Staphylococcus aureus bloodstream infection, with duration set by clearance and complication assessment.

    Monitor liver, kidney, blood count and sodium exposure; continuing cultures require echocardiography and renewed metastatic source search.

    Covers resistant Gram-positive catheter infection while cultures and susceptibility guide narrowing.

    Vancomycin

    Use the local actual-body-weight loading and renal-adjusted intravenous maintenance protocol with measured serum exposure when MRSA or a severe beta-lactam constraint requires it.

    Monitor concentrations, creatinine and concurrent nephrotoxins; avoid leaving susceptible MSSA on glycopeptide therapy when a safe beta-lactam is available.

    Exposes intraluminal biofilm to high local antimicrobial concentration in carefully selected retained lines.

    Antimicrobial lock solution

    Use the exact agent, concentration, volume and dwell time in the local catheter-salvage protocol, always alongside systemic therapy for bloodstream infection.

    Never use alone for systemic infection or when there is S aureus, Candida, tunnel disease, severe sepsis or persistent bacteraemia; prevent accidental systemic bolus.