What is the management approach for suspected CLABSI (Central Line-Associated Bloodstream Infections) versus CRBI (Catheter-Related Bloodstream Infections)?

CLABSI versus CRBI: Key Distinctions and Management

CLABSI (Central Line-Associated Bloodstream Infection) and CRBSI (Catheter-Related Bloodstream Infection) are distinct diagnostic entities with different definitions but overlapping management approaches, where CRBSI requires definitive microbiological proof linking the catheter to infection while CLABSI is a broader surveillance definition that includes any bloodstream infection in a patient with a central line.

Diagnostic Definitions

CRBSI (Catheter-Related Bloodstream Infection)

CRBSI requires definitive microbiological evidence: the same organism must grow from at least one percutaneous blood culture AND from the catheter tip culture (≥15 CFU by roll-plate or ≥102 CFU by sonication), OR paired blood cultures (one from catheter hub, one peripheral) meeting quantitative criteria (≥3-fold higher colony count from catheter) or differential time to positivity (DTP ≥2 hours earlier from catheter) 1.

CLABSI (Central Line-Associated Bloodstream Infection)

CLABSI is a surveillance definition used for epidemiological tracking: any bloodstream infection occurring in a patient with a central line in place for >2 calendar days, with no other identified source of infection 1, 2. This broader definition does not require proving the catheter is the actual source 2.

Diagnostic Approach for Suspected Infection

Blood Culture Collection

• Obtain paired blood cultures BEFORE initiating antibiotics: one from the catheter hub and one from a peripheral vein, with bottles clearly labeled by site 1, 3, 4.
• Use alcoholic chlorhexidine (>0.5%), alcohol, or tincture of iodine for skin preparation with adequate drying time 1, 4.
• If peripheral access is impossible, draw ≥2 blood samples through different catheter lumens 1, 4.

Catheter Tip Culture (When Removed)

• Culture the catheter tip using semiquantitative roll-plate technique (≥15 CFU indicates colonization) or quantitative sonication (≥102 CFU) 1.
• For subcutaneous ports, culture both the port reservoir contents AND the catheter tip 1.

Exit Site Assessment

• If exudate is present, swab for culture and Gram staining 1, 4.

Immediate Catheter Management Decision

Mandatory Catheter Removal Indications

Remove the catheter immediately if ANY of the following are present:

• Severe sepsis, septic shock, or hemodynamic instability 1, 3, 4
• Staphylococcus aureus infection 1, 3, 4
• Pseudomonas species infection 1, 3, 4
• Candida species or other fungal infection 1, 3, 4
• Persistent bacteremia >72 hours despite appropriate antibiotics 1, 3, 4
• Suppurative thrombophlebitis 1, 3, 4
• Endocarditis 1, 3, 4
• Metastatic infection 1

Catheter Salvage May Be Attempted

Salvage is only appropriate for clinically stable patients with:

• Coagulase-negative staphylococci infection AND limited venous access 3, 5
• Corynebacterium jeikeium, Acinetobacter baumannii, or Stenotrophomonas maltophilia 3
• Long-term catheters (tunneled, implanted ports) where replacement is difficult 1, 5

Critical caveat: Immediate reinsertion of a new catheter at the time of removal for suspected CRBSI is associated with increased 30-day mortality (HR 1.48) and should be avoided when possible 6.

Empirical Antimicrobial Therapy

Initial Empirical Coverage

• Start vancomycin empirically in settings with elevated MRSA prevalence 1, 3, 4.
• Consider daptomycin instead if vancomycin MIC >2 μg/mL or high nephrotoxicity risk 3, 4.
• Do NOT use linezolid for empirical therapy 4.

Add Gram-Negative Coverage If:

• Severe illness or septic shock 1
• Neutropenia or immunocompromised state 1
• Femoral catheter location 1
• Use: fourth-generation cephalosporins (cefepime), carbapenems (meropenem), or piperacillin-tazobactam based on local resistance patterns 1, 4.

Add Empirical Antifungal Coverage If:

• Total parenteral nutrition use 3
• Prolonged broad-spectrum antibiotic exposure 3
• Hematologic malignancy 3
• Bone marrow or solid organ transplant 3
• Femoral catheterization 3
• Use: echinocandin (caspofungin, micafungin, anidulafungin) as first-line; fluconazole only if clinically stable with no azole exposure in prior 3 months 4.

Pathogen-Specific Treatment Duration

Coagulase-Negative Staphylococci

• With catheter removal: 5-7 days IV antibiotics 1, 3
• With catheter retention: 10-14 days IV antibiotics PLUS antibiotic lock therapy 3, 5

Staphylococcus aureus

• Uncomplicated (no endocarditis, no metastatic infection): minimum 14 days IV antibiotics after catheter removal 1, 3
• Complicated (endocarditis, osteomyelitis, metastatic infection): 4-6 weeks IV therapy 1, 3
• Obtain transesophageal echocardiogram to exclude endocarditis 1

Enterococcus

• 7-14 days IV antibiotics with catheter removal 1

Gram-Negative Bacilli

• 7-14 days IV antibiotics with catheter removal 1

Candida Species

• Mandatory catheter removal 1, 3
• 14 days antifungal therapy AFTER first negative blood culture and symptom resolution 1, 3

Special Population Considerations

Hemodialysis Patients

• Always remove catheter for: S. aureus, Pseudomonas species, or Candida species 1, 3
• For other pathogens (coagulase-negative staphylococci, other gram-negatives): may attempt salvage with close monitoring, but remove if symptoms persist or metastatic infection develops 1.
• Insert new long-term catheter only after negative blood cultures obtained 1.

Pediatric Patients

• Indications for catheter removal are similar to adults unless no alternative access exists 1, 4
• Antibiotic lock therapy addition to systemic antibiotics improves salvage success in CRBSI (77% vs 68% success) and reduces recurrence (5% vs 18%) 5.
• Monitor closely with repeat blood cultures; remove catheter if clinical deterioration or persistent/recurrent infection 1.

Critical Pitfalls to Avoid

• Never delay blood culture collection before starting antibiotics - this complicates diagnosis and pathogen identification 3, 4.
• Never attempt catheter salvage with S. aureus, Pseudomonas, or Candida - failure increases mortality and hematogenous complications 3.
• Avoid immediate catheter reinsertion at time of removal for suspected CRBSI when possible, as this increases 30-day mortality 6.
• Do not use povidone-iodine for skin preparation - alcoholic chlorhexidine, alcohol, or tincture of iodine are superior 1, 4.
• Do not perform qualitative broth culture of catheter tips - use semiquantitative roll-plate or quantitative sonication methods 1.