What is the clinical definition and management of Central Line-Associated Bloodstream Infection (CRBSI)?

Central Line-Associated Bloodstream Infection (CRBSI): Clinical Definition and Management

Clinical Definition

CRBSI is definitively diagnosed when the same organism grows from at least one percutaneous blood culture and from a culture of the catheter tip, OR when paired blood samples (one from catheter hub, one from peripheral vein) meet specific quantitative or differential time-to-positivity criteria. 1

Diagnostic Criteria (in order of preference):

• Quantitative blood cultures: Colony count from catheter hub blood ≥3-fold greater than colony count from peripheral vein blood 1
• Differential time-to-positivity (DTP): Microbial growth from catheter hub blood sample occurs ≥2 hours before growth from peripheral vein sample 1
• Catheter tip culture: Same organism grows from ≥1 percutaneous blood culture AND from catheter tip culture (using roll plate technique for short-term catheters) 1

Blood Culture Collection Protocol:

• Obtain paired blood samples from catheter hub AND peripheral vein before initiating antibiotics 1
• If peripheral vein access unavailable, draw ≥2 blood samples through different catheter lumens 1
• Clean catheter hub with alcohol, tincture of iodine, or alcoholic chlorhexidine before drawing samples 1
• Mark bottles clearly to indicate collection site 1

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Management Algorithm

Step 1: Immediate Catheter Management (Critical Decision Point)

Remove short-term catheters immediately for: 1, 2

• Gram-negative bacilli (including Enterobacter, Pseudomonas)
• Staphylococcus aureus
• Enterococci
• Fungi
• Mycobacteria

Remove long-term catheters immediately for: 1

• S. aureus (success rate <20% with catheter retention)
• Pseudomonas aeruginosa
• Fungi
• Mycobacteria
• Severe sepsis/septic shock (regardless of pathogen)
• Suppurative thrombophlebitis
• Endocarditis
• Persistent bacteremia >72 hours despite appropriate antibiotics
• Tunnel infection or port abscess

Catheter salvage may be attempted ONLY for: 1

• Long-term catheters with uncomplicated CRBSI due to coagulase-negative staphylococci or streptococci (NOT S. aureus, P. aeruginosa, Bacillus, Micrococcus, Propionibacteria, fungi, or mycobacteria)
• Requires both systemic antibiotics AND antimicrobial lock therapy 1
• Must remove catheter if blood cultures remain positive at 72 hours 1

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Step 2: Empirical Antibiotic Therapy (Start Before Culture Results)

Gram-positive coverage (mandatory): 1

• Vancomycin for settings with elevated MRSA prevalence
• Daptomycin if local MRSA isolates have vancomycin MIC >2 μg/mL 1
• Do NOT use linezolid empirically (associated with increased mortality in unconfirmed bacteremia) 1, 3

Gram-negative coverage (based on clinical factors): 1

• Fourth-generation cephalosporin (cefepime), OR
• Carbapenem (meropenem, imipenem), OR
• β-lactam/β-lactamase combination (piperacillin-tazobactam)
• Base selection on local susceptibility patterns and severity of illness 1

Combination therapy for multidrug-resistant gram-negatives when: 1

• Neutropenic patients
• Severe sepsis/septic shock
• Known colonization with MDR pathogens (Pseudomonas, Acinetobacter)
• Use two different antibiotic classes until susceptibilities available, then de-escalate 1

Antifungal coverage (add empirically if): 1

• Total parenteral nutrition use
• Prolonged broad-spectrum antibiotic exposure
• Hematologic malignancy
• Bone marrow or solid-organ transplant recipient
• Femoral catheter in critically ill patient
• Candida colonization at multiple sites
• Use echinocandin (preferred) or fluconazole (only if no azole exposure in past 3 months AND low risk of C. krusei/C. glabrata) 1

Special consideration for femoral catheters: 1

• Must cover gram-positives, gram-negatives, AND Candida species empirically 1

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Step 3: Definitive Therapy (After Susceptibility Results)

De-escalate to narrowest-spectrum agent with activity against identified pathogen 4, 3

Pathogen-specific adjustments:

• Enterococcus faecalis: Ampicillin if susceptible; vancomycin if resistant 3
• Enterobacter species: Fourth-generation cephalosporin if susceptible; carbapenem if resistant or AmpC β-lactamase suspected (avoid third-generation cephalosporins due to inducible resistance) 4, 3
• S. aureus: Continue vancomycin or switch to nafcillin/cefazolin if methicillin-susceptible 1

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Step 4: Treatment Duration

Uncomplicated CRBSI (after catheter removal): 1, 4, 3

• 7-14 days for most pathogens
• Day 1 = first day of negative blood cultures 1

Complicated CRBSI requires 4-6 weeks: 1, 3

• Persistent bacteremia/fungemia >72 hours after catheter removal
• Endocarditis
• Suppurative thrombophlebitis
• Metastatic infection

Osteomyelitis: 1

• Pediatric patients: 4-6 weeks
• Adults: 6-8 weeks

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Step 5: Monitoring and Follow-up

Obtain follow-up blood cultures 72 hours after initiating appropriate therapy 1, 4, 3

If cultures remain positive at 72 hours: 1, 3

• Remove any retained catheter immediately
• Perform transesophageal echocardiography to evaluate for endocarditis 4, 3
• Evaluate for suppurative thrombophlebitis or metastatic complications 4

Additional TEE indications: 3

• New cardiac murmur
• Embolic phenomena
• Persistent fever despite appropriate therapy

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Critical Pitfalls to Avoid

• Never attempt catheter salvage with gram-negative bacilli, S. aureus, enterococci, fungi, or mycobacteria in short-term catheters (unacceptably high failure rates and mortality) 1, 2
• Do not use linezolid empirically before bacteremia is confirmed (increased mortality) 1, 3
• Avoid third-generation cephalosporins for Enterobacter species (inducible AmpC β-lactamase causes treatment failure) 3
• Do not use thrombolytic agents as adjunctive therapy (not recommended) 1
• Do not assume all coagulase-negative staphylococci are contaminants - obtain additional cultures if single positive result before dismissing as contamination 1
• For hemodialysis patients with gram-negative CRBSI, insert new temporary catheter at different anatomical site rather than exchanging over guidewire 2