Is it okay to draw blood cultures from a central line (central venous catheter)?

Drawing Blood Cultures from Central Venous Catheters

Yes, it is appropriate to draw blood cultures from a central venous catheter, but this should be paired with peripheral blood cultures for accurate diagnosis of catheter-related bloodstream infections (CRBSI). 1

Recommended Approach for Blood Culture Collection

When CRBSI is Suspected:

• Collect paired blood samples from both the catheter and a peripheral vein 1
• Obtain the same volume of blood from each site 1
• If peripheral access is impossible, draw two blood samples at different times from two different catheter lumens 1
• Use proper skin antisepsis with alcohol, alcoholic chlorhexidine (>0.5%), or tincture of iodine before collection 1
• Allow adequate drying time for the antiseptic to prevent contamination 1

Interpretation of Results:

• CRBSI is diagnosed when the same organism grows from both catheter and peripheral cultures with either:
  • Quantitative blood cultures showing ≥3-fold higher colony count in the catheter sample compared to peripheral sample 1
  • Differential time to positivity (DTP) showing growth from catheter hub at least 2 hours before peripheral sample 1

Advantages and Limitations

Advantages:

• High negative predictive value (98-99%) - excellent for ruling out bloodstream infections 2, 3
• Allows for proper diagnosis of CRBSI when paired with peripheral cultures 1, 4
• Essential when the catheter is suspected as the infection source 4

Limitations:

• Lower positive predictive value (61-63%) compared to peripheral venipuncture (73-78%) 2, 3
• Higher contamination rates compared to peripheral draws (8% vs 4%) 5
• Central venous catheter cultures have lower specificity than peripheral venipuncture 3

Special Considerations

• If there is exudate at the catheter exit site, collect a swab for culture and Gram staining 1
• For suspected pulmonary artery catheter infection, culture the introducer tip 1
• Blood cultures should be obtained before starting antibiotic therapy 1
• Avoid collecting cultures from all catheter lumens as there is insufficient evidence supporting this practice 1

Catheter Management

• Do not routinely remove non-tunneled CVCs in patients with fever and mild to moderate disease 1
• Remove the catheter if there are evident signs of local infection, clinical sepsis, or positive paired blood cultures 1
• After catheter removal in patients with CRBSI, non-tunneled catheters may be reinserted after appropriate antimicrobial therapy has begun 1

Common Pitfalls to Avoid

• Failing to collect paired samples from both catheter and peripheral sites 1, 4
• Using povidone-iodine instead of alcoholic chlorhexidine or alcohol for skin preparation 1
• Not allowing adequate drying time for antiseptics 1
• Interpreting positive catheter cultures without clinical context or confirmation 2, 3
• Removing catheters unnecessarily based solely on positive cultures without considering clinical status 1