Blood Culture Collection Guidelines

Primary Recommendations

The Infectious Diseases Society of America recommends obtaining blood cultures from peripheral veins whenever possible, as this provides the gold standard for diagnosis 1, 2
When catheter-related bloodstream infection (CRBSI) is suspected, obtain paired blood samples—one from the catheter and one from a peripheral vein—before initiating antimicrobial therapy, allowing for quantitative comparison and differential time to positivity (DTP) to confirm CRBSI 1, 2, 3

A colony count from the catheter that is ≥3-fold greater than peripheral blood confirms CRBSI, with a strength of evidence based on clinical studies 3, 2
Growth from catheter blood ≥2 hours before peripheral blood growth also confirms CRBSI, highlighting the importance of timely sampling 3, 2
The same organism must grow from both sites to establish CRBSI, ensuring accurate diagnosis 1, 2

Meticulous skin preparation with alcoholic chlorhexidine (>0.5%) or alcohol or tincture of iodine is mandatory to minimize contamination, with adequate contact and drying time before needle insertion 1, 2, 3
Hub cleaning with the same antiseptic agents when drawing through catheters, and the use of phlebotomy teams when available, can reduce contamination rates 1, 2, 3

In ICU patients with arterial catheters, these can be used for blood culture collection, though they show intermediate contamination rates, and should be included in sampling along with central line and peripheral sites 4, 5
Removal of arterial catheters is recommended if the patient has unexplained sepsis or purulence at the insertion site, with cultures obtained before removal 4, 5