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Blood Cultures

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Megan Brashear, CVT, VTS (ECC), demonstrates the proper preparation and procedure for collecting blood cultures performed in a dog hospitalized for a fever of unknown origin.

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Megan Brashear's picture
Megan Brashear


Enrolled: 07/2011

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Laura Ryan's picture

Our clinic always pulls enough blood for both vials at the same time. What is the advantage of waiting an hour to pull for the second vial?


Megan Brashear's picture

Hi Ryan,
By both vials I am assuming you're talking about aerobic and anaerobic which is a slightly different issue. Because blood cultures can be tricky to determine if the organism that is grown is from the blood and not from the skin or other contaminant, and because bacteria can be shed into the blood at different time intervals, we draw two separate cultures from two separate vessels an hour apart. If the lab grows the same organism from both separate cultures, we can be more confident that it is indeed from the blood. This depends on your hospital protocol, if you are having success then keep it up!

Kristen Black's picture

What was the medium used in the blood culture? Also, did the cultures come back with anything interesting on this patient?

Megan Brashear's picture

Kristen, here we use Oxoid Signal Blood Culture bottles, ordered through our outside lab. In this particular patient they did not grow anything exciting or interesting and he did well!

Heather Cooley's picture

This could be lab specific, but the outside lab we acquire our blood culture medium from has a far more extensive preparation prior to drawing the sample.
1.Surgical prep with chlorhex scrub and rinse with sterile water.
2.Apply 1-2% tincture of iodine or povidone-iodine and allow to dry.
3.Remove the iodine with 70% alcohol.
4.Wipe with sterile water and allow to dry.

I've always been instructed that if we are doing a two or three time point culture to draw each sample from a different location. Is this standard for you all as well?

Thank you for all the great information!

Jessica Waters-Miller's picture

Hi Heather,
Yes, you are exactly right. The purpose of multiple time point cultures is to decrease the number of false positives. And the purpose of doing multiple locations is to decrease the number of false positives as well. The surgical prep and location can vary upon situation and Doctor preference. Thanks for the great question!
That is also a great protocol your lab has.