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November 2011

#83896 Mycobacterium tuberculosis Infection Determination by QuantiFERON-TB Gold, Blood: A Quick Reference for Specimen Collection and Processing

Collection

Collection must be performed using 1 of the following kits:

  • QuantiFERON-QTB Gold In-Tube Collection Kit (Supply #T628)
  • QuantiFERON-QTB High Altitude Collection Kit (Supply #T649)
    Note: This kit is for clients in locations with an altitude greater than 3,350 feet above sea level.

1. Collect 1-mL blood by venipuncture into each of the 3 tubes.

  • Expect these tubes to fill slowly.
  • Leave tube on the needle for 2–3 seconds after the flow of blood has stopped.
  • When tube is upright, blood must meet the small black mark on the label.
  • Use of butterfly needle is not recommended, but if necessary, first collect other required tubes or use a “purge” tube to remove the air from the line. Then proceed to collect the QTB tubes.
  • These tubes are manufactured to draw 1 mL of blood and perform optimally within the range of 0.8 to 1.2 mL. (Figure 1) Underfilled or overfilled specimens will be rejected.
  • If the level of blood is not close to the black indicator line, another blood specimen should be collected.
Figure 1 QTB validated fill range.

Figure 1 QTB validated fill range.
Used with permission. Cellestis Inc.

2. Immediately shake the tubes firmly for 5 seconds.

  • Entire inner surface of the tube must be coated with blood. (Figure 2)
  • Over energetic shaking may cause gel disruption and could lead to aberrant results.
Figure 2 Blood should coat the entire inner surface

Figure 2 Blood should coat the entire inner surface

3. Label tubes appropriately. The label should be placed below colored QuantiFERON band, so back window is visible on all 3 collection tubes.

4. Maintain tubes at room temperature until incubation.

Incubation and Centrifugation

Immediate incubation is recommended, but must be started no later than 16 hours after collection.

1.Incubate all 3 tubes upright at 37°C for 16–24 hours

  • If incubation is delayed, remix tubes by inverting for 5 seconds immediately before starting incubation (hemolyzed plasma is acceptable).
  • Improper incubation may cause erroneous results.
  • Humidity and CO2 not required.

2. Centrifuge tubes for 15 minutes at 3000 RCF (g) after incubation.

3. Place all 3 tubes in the QTB Transport bag (supplied). (Figure 3)

Figure 3 QTB transport kit

Figure 3 QTB transport kit

4. Store refrigerated at 2°C to 8°C.

  • Specimens are stable for 28 days when refrigerated.

Shipping

Ship QTB kit at refrigerated temperature (2°C–8°C). (Figure 3)

 

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