What is the treatment approach for Central Line-Associated Bloodstream Infections (CLABSI) versus Catheter-Related Bloodstream Infections (CRBSI)?

CLABSI versus CRBSI: Key Distinctions and Treatment Implications

Fundamental Definitions

CRBSI (Catheter-Related Bloodstream Infection) is a clinical diagnosis requiring microbiological proof that the catheter is the source, while CLABSI (Central Line-Associated Bloodstream Infection) is a surveillance definition that identifies any bloodstream infection in a patient with a central line present for >2 calendar days without requiring proof of causation 1.

Diagnostic Criteria

CRBSI Diagnosis:

• Requires culture of the same organism from both the catheter tip and at least one percutaneous blood culture 1
• Alternatively, differential time to positivity (DTP) ≥2 hours earlier from the catheter hub sample compared to peripheral vein sample 1, 2, 3
• This DTP method is highly sensitive and specific for CRBSI 2, 3

CLABSI Diagnosis:

• Does not require proving the catheter caused the infection 1
• Simply identifies bloodstream infection with central line present >2 calendar days and no other identifiable source 1

Critical Treatment Differences

The treatment approach is essentially identical for both CLABSI and CRBSI once infection is confirmed, as both involve central venous catheter-associated bloodstream infections. The key distinction lies in diagnosis and surveillance, not management.

Immediate Catheter Management Decision

Mandatory Immediate Catheter Removal Indications:

• S. aureus bacteremia 4, 1, 2, 3
• Pseudomonas species 4, 1, 2, 3
• Candida species 4, 1, 2, 3
• Severe sepsis or hemodynamic instability 4, 1, 2, 3
• Persistent bacteremia beyond 72 hours despite appropriate antibiotics 4, 1, 2, 3
• Suppurative thrombophlebitis or endocarditis 4
• Purulence or erythema at catheter exit site 4

Catheter Salvage May Be Attempted:

• Clinically stable patients with limited venous access 4, 2, 3
• Infections caused by coagulase-negative staphylococci 4, 2, 3
• Corynebacterium jeikeium, Acinetobacter baumannii, or Stenotrophomonas maltophilia 4, 3
• Must use both systemic antibiotics AND antimicrobial lock therapy 4, 2

Empirical Antimicrobial Therapy

Initial Coverage:

• Vancomycin as first-line in settings with high MRSA prevalence 1, 3
• Add gram-negative coverage based on local antibiogram (third-generation cephalosporin, carbapenem, or β-lactam/β-lactamase combination) 4, 1
• Switch to cefazolin if methicillin-susceptible S. aureus identified 4

Indications for Empirical Antifungal Therapy:

• Septic patients with total parenteral nutrition 3
• Prolonged broad-spectrum antibiotic use 3
• Hematologic malignancy or transplant recipients 3
• Femoral catheterization 3

Pathogen-Specific Treatment Duration

Coagulase-Negative Staphylococci:

• 5-7 days IV antibiotics if catheter removed 2, 3
• 10-14 days IV antibiotics plus antibiotic lock therapy if catheter retained 4, 2, 3

S. aureus:

• Minimum 10-14 days IV antibiotics after catheter removal for uncomplicated cases 1, 3
• 4-6 weeks for complicated infections (persistent bacteremia, endocarditis, suppurative thrombophlebitis) 4, 1, 3
• Catheter salvage has only 20% success rate and is not recommended 4

Candida species:

• Mandatory catheter removal 3
• 14 days of antifungal therapy after first negative blood culture and symptom resolution 3
• Treatment without catheter removal has low success rate and higher mortality 4

Gram-Negative Bacilli:

• Catheter removal preferred, especially for Pseudomonas 4
• May attempt salvage for other gram-negatives in stable patients with limited access 4

Antibiotic Lock Therapy

Indications:

• Only as adjunct to systemic therapy, never alone 4, 2
• For long-term catheters when salvage is the goal 4
• Administered for 10-14 days 4
• Dwell times should not exceed 48 hours before reinstallation; preferably every 24 hours 4
• For hemodialysis patients, renew after each dialysis session 4

Success Rates:

• 87-100% for gram-negative pathogens 4
• 75-84% for coagulase-negative staphylococci 4
• Only 40-55% for S. aureus (not recommended) 4

Special Population: Hemodialysis Patients

Always remove catheter for:

• S. aureus 4, 2, 3
• Pseudomonas species 4, 2
• Candida species 4, 2

May consider guidewire exchange:

• If symptoms resolve within 2-3 days of antibiotics 4
• No evidence of metastatic infection 4
• Infection due to coagulase-negative staphylococci or other gram-negatives 4

Follow-Up Requirements

Obtain repeat blood cultures 72 hours after initiating therapy to document clearance 1. Persistent positive cultures at 72 hours indicate treatment failure and necessitate extended therapy plus evaluation for metastatic infection 1.

Consider transesophageal echocardiography (TEE) for:

• S. aureus bacteremia to rule out endocarditis 4, 2

Critical Pitfalls to Avoid

• Never delay obtaining blood cultures before starting antibiotics, as this complicates diagnosis and pathogen identification 2, 3
• Never attempt catheter salvage with S. aureus, Pseudomonas, or Candida, as failure/delay increases mortality and hematogenous complications 2, 3
• Never use antibiotic lock therapy alone without systemic antibiotics 4, 2
• Never routinely replace CVCs or perform guidewire exchanges to prevent infection 4, 2