Blood cultures

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Blood cultures drawn by peripheral arterial or venepuncture are the gold standard for diagnosing bacteremia. The overlying skin should be antiseptically scrubbed with 2% chlorhexidine or betadine. Chlorhexidine should be in contact with the skin for at least 30 seconds before removal with sterile water and the subsequent blood draw. Betadine must dry completely before skin puncture.

Optimally 1 mL of blood should be sent to the lab in an aerobic blood culture bottle; 0.5 mL of blood is an absolute minimum.

Blood cultures may be drawn from a freshly-placed sterile umbilical line. If blood cultures are drawn from an older umbilical line, the existing stopcock must be replaced with a new one and sterile technique used to pull the blood from the line.

Blood cultures may be drawn from central venous catheters (Broviac® Catheters and PICCs) when clinically indicated. However, older PICC lines frequently will not draw back. Furthermore, a pure blood sample may not be attainable, and a specimen containing some IV fluid is acceptable. Strict sterile technique with a sterile field and gloves is essential. The line must be adequately flushed afterwards to reduce the risk of clotting in the line.

For information on viral cultures, click here

References:

Schelonka RL, et al. Volume of blood required to detect common neonatal pathogens. J Pediatr 1996; 129: 275-8.