What are the Infectious Diseases Society of America (IDSA) guidelines for diagnosing and managing a patient with a suspected Central Line-Associated Bloodstream Infection (CLABSI)?

CRBSI Diagnosis and Management per IDSA Guidelines

Diagnosis of CRBSI

For suspected CRBSI, obtain paired blood cultures simultaneously—one from the catheter hub and one from a peripheral vein—before starting antibiotics, and use either quantitative culture methods (≥3-fold higher colony count from catheter vs. peripheral) or differential time to positivity (≥2 hours earlier growth from catheter) to confirm the diagnosis. 1

Blood Culture Collection Technique

• Always obtain blood cultures before initiating antimicrobial therapy 1
• Draw paired samples from both the catheter hub and a peripheral vein, clearly labeling each bottle to indicate the source 1
• Clean the catheter hub meticulously with alcohol, alcoholic chlorhexidine (>0.5%), or tincture of iodine, allowing adequate drying time 1
• For peripheral venipuncture, use the same antiseptic agents rather than povidone-iodine, which requires longer contact time 1
• If peripheral access is unavailable, draw blood cultures from ≥2 different catheter lumens as an alternative, though this is less ideal 1

Definitive Diagnostic Criteria

A definitive CRBSI diagnosis requires one of three methods:

1. Catheter tip + peripheral blood culture: Same organism grows from ≥1 peripheral blood culture AND from the catheter tip culture (>15 CFU by roll-plate method or >10² CFU by sonication) 1

2. Quantitative blood cultures: Colony count from catheter hub blood is ≥3-fold greater than from peripheral vein blood 1

3. Differential time to positivity (DTP): Growth from catheter-drawn blood occurs ≥2 hours before growth from peripheral blood 1

Catheter Culture Methods

• For short-term catheters: Use the roll-plate technique for catheter tip culture (semiquantitative method) 1
• Culture the catheter tip (distal 5 cm), not the subcutaneous segment 1
• Growth of >15 CFU by roll-plate or >10² CFU by sonication indicates catheter colonization 1
• Do not use qualitative broth cultures—they lack specificity 1
• For pulmonary artery catheters, culture the introducer tip rather than the catheter itself 1
• For subcutaneous ports, culture both the port reservoir contents and the catheter tip 1

Clinical Assessment

• If catheter exit site shows purulence or exudate, swab the drainage for Gram stain and culture 1
• For long-term catheters, growth of <15 CFU of the same organism from both insertion site and hub cultures strongly suggests the catheter is NOT the source 1

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Management of CRBSI

Empiric Antimicrobial Therapy

Start empiric antibiotics immediately after obtaining blood cultures when CRBSI is suspected, using vancomycin for gram-positive coverage (especially in settings with elevated MRSA prevalence) plus gram-negative coverage based on local susceptibility patterns. 2

• Use a fourth-generation cephalosporin, carbapenem, or β-lactam/β-lactamase inhibitor combination for gram-negative coverage 2
• Tailor therapy once culture and susceptibility results are available 1

Catheter Removal Decisions

For short-term catheters (non-tunneled CVCs and arterial catheters):

• Remove immediately if: 1

  • Purulence or erythema at insertion site
  • Unexplained sepsis or hemodynamic instability
  • CRBSI due to S. aureus, gram-negative bacilli (including P. aeruginosa), enterococci, fungi, or mycobacteria
  • Persistent fever/bacteremia >72 hours despite appropriate antibiotics
  • Complications such as endocarditis, suppurative thrombophlebitis, or osteomyelitis

• Remove the catheter and culture the tip when CRBSI is suspected; do not obtain catheter cultures routinely 1

• If catheter was exchanged over a guidewire and tip culture is positive, remove it and place a new catheter at a different site 1

For long-term catheters (tunneled catheters, ports):

• Remove if: 1

  • Severe sepsis or hemodynamic instability
  • Suppurative thrombophlebitis or endocarditis
  • Tunnel infection or port abscess (also requires incision/drainage if indicated)
  • Persistent bacteremia/fungemia >72 hours despite appropriate therapy
  • CRBSI due to S. aureus, P. aeruginosa, Bacillus species, Micrococcus species, Propionibacteria, fungi, or mycobacteria

• Attempt catheter salvage with systemic antibiotics plus antimicrobial lock therapy for uncomplicated CRBSI due to less virulent organisms (e.g., coagulase-negative staphylococci) in patients with limited vascular access 1

Duration of Antimicrobial Therapy

Day 1 of therapy is defined as the first day negative blood cultures are obtained 1

Organism-specific treatment durations (after catheter removal):

Organism	Duration	Clinical Context
Coagulase-negative staphylococci	5-7 days	Uncomplicated infection [1]
	10-14 days	Standard recommendation [2]
	4-6 weeks	Complicated (endocarditis, osteomyelitis) [1]
S. aureus	14 days minimum	Uncomplicated, after catheter removal [1]
	4-6 weeks	Complicated or persistent bacteremia >72h [1,2]
Enterococcus	7-14 days	After catheter removal [1]
Gram-negative bacilli	7-14 days	After catheter removal [1]
Candida species	14 days	After first negative blood culture and catheter removal [1]

Monitoring and Follow-up

• Obtain additional blood cultures if fever persists >72 hours on appropriate therapy 1
• Remove the catheter if blood cultures remain positive 72 hours after initiating appropriate antibiotics 1
• For single positive blood culture growing coagulase-negative staphylococci, obtain additional cultures from catheter and peripheral vein before starting antibiotics to confirm true bacteremia 1

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Common Pitfalls to Avoid

• Do not use povidone-iodine for skin preparation—it requires 1.5-2 minutes contact time vs. 30 seconds for chlorhexidine or alcohol 1
• Do not routinely culture all catheter lumens—there is insufficient evidence to support this practice and it increases costs 1, 2
• Do not use thrombolytic agents (urokinase) as adjunctive therapy—they are not recommended 1
• Do not attempt catheter salvage for S. aureus, P. aeruginosa, fungi, or mycobacteria—these require catheter removal 1
• Do not delay catheter removal in hemodynamically unstable patients—remove immediately and place new catheter at different site 1, 2