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Differential Time to Positivity
|Test group||Bacterial culture|
|In House Availability||Set up daily, day and evening shifts|
|Method||BacT/ALERT blood culture system|
|Collection Instructions||For detailed instructions, see nursing manual or instructions in blood culture collection kits.
Peripheral vein and CVC line samples must be obtained within 15 minutes of each other.
The volumes of blood obtained from the peripheral vein & from the CVC must match. (e.g. if only 12 mLs is obtained from peripheral stick, obtain only 12 mLs from CVC).
Draw peripheral blood sample first since the amount of blood obtained will determine how much is obtained from the CVC.
Inoculate one set of aerobic & anaerobic bottles with the peripheral sample, dividing the volume in half for each bottle. Label bottles and a microbiology requisition as "peripheral".
Inoculate a second set of aerobic & anaerobic bottles with the line sample, dividing the volume in half for each bottle. Label bottles and a microbiology requisition as "line".
On both requisitions, check "Aerobic & anaerobic" culture box and write "Time to Positivity". Put all 4 bottles and 2 lab slips in the same specimen bag and send to the lab.
|Container type||FAN Aerobic & SN Anaerobic blood culture bottles (2 sets)|
|Amount to Collect||40 mL blood|
|Sample type||Whole blood|
|Preferred volume||10 mL blood in each bottle|
|Min. Volume||5 mL blood (adults), 1 mL blood (pediatrics) in each bottle|
|UCSF Rejection Criteria||Peripheral and line samples received in lab at different times or with collection times >15 mins apart.|
|Processing notes||Accession one set and then the next. Enter in SREQ, code TTP TIME TO POSITIVITY. Send both sets of cultures to China Basin in one bag. At China Basin, load both sets of cultures into the BacT/ALERT at the same time.|
|Normal range||No growth|
|Critical value||Gram stain results from the first positive blood culture on a patient will be phoned.
Additional calls only made if > 7 days have elapsed since first call or a different organism is identified.
|Synonyms||catheter tip; catheter infection; blood culture|
|Stability||Stable at room temperature|
|Turn around times||6 days|
|Additional information||If organisms grow in the sample drawn through the line at least two hours earlier than from the peripheral blood, then the line is considered to be the source of infection.|
|Last Updated||4/5/2012 9:52:28 AM|
If you have additional questions regarding this test, please call: 415-353-1667