The following steps are critical to the proper collection of blood cultures.
The blood culture bottles should be examined prior to use for signs of deterioration and damage.
- Broth in the bottle should be clear. Cloudiness or darkening of the broth are indications of deterioration or contamination.
- An expiration date is printed on the label of the blood culture bottle. The bottle cannot be used beyond that date.
- Using an expired or deteriorated blood culture bottle may affect patient culture results.
Blood collected for culture should be collected by venipuncture whenever possible. An intravenous catheter or line is associated with increased culture contamination rates and should not be used for the collection of blood cultures unless it is the only option. If one culture is obtained from an intravenous catheter or line, it is a good practice to pair it with a second culture collected by venipuncture so that the culture results can be compared. If the blood culture that was collected through the line is positive, and the culture collected by venipuncture is negative, the positive result was most likely the result of a contaminant.
Collecting blood for culture by arterial puncture is also not recommended. Blood culture growth from venous blood is equivalent to growth from arterial blood, so there is no advantage to collecting blood from an artery, which is a more painful process for the patient.
