Blood Culture Sampling from Multiple Lumens in Suspected CRBSI
You do not need to draw blood cultures from every lumen in suspected CRBSI, but if peripheral venous access is unavailable, drawing from at least 2 different lumens is recommended, though the evidence explicitly states it remains unclear whether all lumens should be sampled. 1
Primary Diagnostic Approach: Peripheral + Central Sampling
The gold standard approach when CRBSI is suspected involves:
- Draw paired blood cultures simultaneously from one catheter lumen AND a peripheral vein before starting antibiotics 1, 2
- This allows for either quantitative comparison (≥3-fold higher colony count from catheter) or differential time to positivity (DTP ≥2 hours earlier growth from catheter) 1, 2
- Both methods have 100% sensitivity and specificity for CRBSI diagnosis 3
When Peripheral Access is Unavailable
If you cannot obtain peripheral blood:
- Draw blood cultures from at least 2 different catheter lumens (Grade B-III recommendation) 1
- The IDSA guidelines explicitly acknowledge: "It is unclear whether blood cultures should be drawn through all catheter lumens in such circumstances" (Grade C-III) 1
Evidence Supporting Selective Multi-Lumen Sampling
Research provides some guidance on which lumen to prioritize:
- In 83% of CRBSI cases in febrile neutropenic patients, the infection originated from the lumen used for parenteral nutrition and blood products 4
- However, 17% of infections originated from other lumens, suggesting each lumen represents a potential source 4
- When comparing 2 CVC lumens using DTP, this approach showed 76.5% sensitivity and 88.9% specificity for CRBSI diagnosis 5
Practical Algorithm
Step 1: Attempt peripheral venous blood culture + one central line culture (preferably from the lumen used for PN/blood products if multi-lumen) 1, 4
Step 2: If peripheral access impossible, draw from ≥2 different catheter lumens 1
Step 3: Use quantitative cultures (≥3-fold difference) or DTP (≥2 hour difference) to confirm CRBSI 1, 2
Critical Technical Points
- Clean catheter hubs meticulously with alcohol, alcoholic chlorhexidine (>0.5%), or tincture of iodine before drawing 1, 2
- Label bottles clearly to indicate which lumen/site each sample came from 1
- Obtain all cultures before initiating antimicrobial therapy 1, 2
Common Pitfalls to Avoid
- Do not rely on cultures from catheter lumens alone without comparison - this cannot distinguish CRBSI from catheter colonization 6, 2
- Do not assume sampling one lumen is sufficient in multi-lumen catheters - while the PN lumen is most commonly infected, 17% of infections arise from other lumens 4
- Do not routinely culture all lumens as standard practice - the evidence does not support this, and it increases cost without proven benefit 1