What is the management approach for Central Line-Associated Bloodstream Infections (CLABSIs) versus Catheter-Related Bloodstream Infections (CRBSIs)?

CLABSI vs CRBSI: Understanding the Distinction and Management Implications

CLABSI (Central Line-Associated Bloodstream Infection) is a surveillance definition used for epidemiological tracking, while CRBSI (Catheter-Related Bloodstream Infection) is a clinical diagnosis requiring microbiological proof that the catheter is the source—the key difference is that CLABSI does not require proving the catheter caused the infection, whereas CRBSI does. 1

Definitional Framework

CRBSI (Catheter-Related Bloodstream Infection)

• Requires definitive microbiological evidence linking the catheter to bloodstream infection through one of two methods: 1
  • Culture of the same organism from both the catheter tip (>15 CFU by semiquantitative roll-plate or >102 CFU by quantitative sonication) AND at least one percutaneous blood culture 1
  • OR differential time to positivity ≥2 hours earlier from the catheter hub sample compared to peripheral vein sample 1, 2
  • OR quantitative blood cultures showing ≥3-fold higher colony count from catheter hub versus peripheral sample 1

CLABSI (Central Line-Associated Bloodstream Infection)

• A surveillance definition that identifies any bloodstream infection in a patient with a central line in place for >2 calendar days, with no other identifiable source 1
• Does not require proving the catheter caused the infection—simply temporal association 1
• Used primarily for quality metrics and epidemiological tracking, not clinical decision-making 1

Critical Clinical Implication

The distinction matters because CLABSI may overestimate true catheter-related infections, potentially leading to unnecessary catheter removal in patients who have bloodstream infections from other sources (e.g., pneumonia, surgical site infections) 1. Conversely, using CRBSI criteria ensures you're only removing catheters when they are definitively the source.

Diagnostic Approach for Suspected Catheter Infection

Blood Culture Technique

• Always obtain paired blood cultures: one from the catheter hub AND one from a peripheral vein before starting antibiotics 1, 2
• Do not draw cultures solely from the catheter port—this increases false-positive rates from skin contaminants 1
• If exit site exudate is present, swab for culture and Gram stain 1

Interpretation of Results

• Differential time to positivity ≥2 hours (catheter sample positive before peripheral) is highly sensitive and specific for CRBSI 1, 2
• Most laboratories can perform differential time to positivity even if quantitative cultures are unavailable 1
• For removed catheters: culture the catheter tip (not subcutaneous segment) using roll-plate technique for short-term catheters 1

Management Algorithm Based on Pathogen and Catheter Type

Immediate Catheter Removal Required (Non-Negotiable)

Remove the catheter immediately in the following scenarios: 1, 3

• S. aureus bacteremia (success rate of catheter salvage <20%) 1
• Gram-negative bacilli including Klebsiella, Pseudomonas, Acinetobacter 1, 3
• Candida species 1
• Enterococci 3
• Mycobacteria 3
• Severe sepsis or hemodynamic instability 1, 3
• Persistent bacteremia >72 hours despite appropriate antibiotics 1, 3
• Complicated infections: endocarditis, suppurative thrombophlebitis, osteomyelitis 1, 3
• Tunnel infection or port abscess 1

Catheter Salvage May Be Attempted (Selective Cases)

Consider salvage only in clinically stable patients with limited venous access and uncomplicated infection caused by: 1

• Coagulase-negative staphylococci
• Corynebacterium jeikeium
• Acinetobacter baumannii
• Stenotrophomonas maltophilia

Salvage strategy requirements: 1

• Use both systemic antibiotics AND antimicrobial lock therapy
• Obtain repeat blood cultures at 72 hours
• Remove catheter if cultures remain positive at 72 hours 1, 3

Empirical Antibiotic Therapy

Initial Coverage (Before Culture Results)

• Vancomycin is appropriate empirical therapy in areas with high MRSA prevalence 1, 3
• In countries without high MRSA rates, use anti-staphylococcal beta-lactam as first-line 1
• Add gram-negative coverage in: 1, 3
  • Severe illness or sepsis
  • Neutropenic or immunocompromised patients
  • Femoral catheter placement
  • Hemodialysis patients

Gram-Negative Coverage Options

Choose based on local antibiogram: 1, 3

• Extended-spectrum penicillin (piperacillin/tazobactam)
• Cephalosporin (cefepime)
• Carbapenem (meropenem)

Antibiotic Duration

Uncomplicated CRBSI

• 10-14 days after catheter removal for coagulase-negative staphylococci 1, 3
• 10-14 days minimum for S. aureus after catheter removal 1, 3

Persistent Bacteremia

• 4-6 weeks if blood cultures remain positive >72 hours after catheter removal despite appropriate antibiotics 1, 3

Complicated Infections

• 4-6 weeks for endocarditis or suppurative thrombophlebitis 1, 3
• 6-8 weeks for osteomyelitis in adults 1, 3

Mandatory Follow-Up

Obtain repeat blood cultures 72 hours after initiating therapy to document clearance of bacteremia—this is non-negotiable 3. Persistent positive cultures at 72 hours indicate treatment failure and necessitate extended therapy plus evaluation for metastatic infection 3.

Common Pitfalls to Avoid

• Do not routinely remove catheters in stable patients with fever of unknown origin without microbiological evidence 1
• Avoid guidewire exchanges of non-tunneled CVCs to prevent CRBSI—this does not reduce infection risk 1
• Do not use qualitative broth culture of catheter tips—use semiquantitative roll-plate or quantitative sonication methods 1
• Never delay S. aureus catheter removal—failure to remove promptly increases risk of hematogenous complications and mortality 1
• For hemodialysis patients with CRBSI, insert new temporary catheter at different anatomical site—do not exchange over guidewire unless absolutely no alternative exists 3

Special Considerations for Long-Term Catheters

• Tunneled catheters and ports: the catheter hub is the predominant source of infection rather than the insertion site 1
• For port removal due to suspected CRBSI, send both the port reservoir contents AND catheter tip for culture 1
• Growth of <15 CFUs/plate of the same microbe from both insertion site and catheter hub cultures strongly suggests the catheter is NOT the source 1