UCSF Navigation Bar

UCSF Departments of Pathology & Laboratory Medicine Home Page

Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

Internal Resources

Click here for more information about laboratory operations and procedures

If you have additional questions regarding this test, please call: 415-353-1667

Search Our Test Menu

Differential Time to Positivity

Item Value
Approval req'd? No
Available Stat? No
Test code P060 & P061
Test group Bacterial culture
Performed by Microbiology
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 as "peripheral" and submit with a microbiology requisition for a DTTP Peripheral Blood Culture.
Inoculate a second set of aerobic & anaerobic bottles with the line sample, dividing the volume in half for each bottle. Label bottles as "line" and submit with a microbiology requisition for a DTTP Central Blood Culture.

Put all 4 bottles and 2 lab slips in the same specimen bag and send to the lab.
Container type FA 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
Adults: 5 mL blood in each bottle
Pediatric patients 1 mL blood in each bottle ( 1.5 mL if only collecting an aerobic bottle)
UCSF Rejection Criteria Peripheral and line samples received in lab at different times or with collection times >15 mins apart.
Processing notes Maintain sample at room temperature. Accession one set and then the next. 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 10 hours 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.
CPT coding 87040
LOINC code 600-7
Last Updated 1/14/2014 8:46:59 AM
Entry Number 1117
UCSF home page UCSF home page About UCSF Search UCSF UCSF Medical Center