QuantiFERON®-TB Gold In-Tube Test

Tuberculosis (TB) is a contagious disease caused by the bacterium called Mycobacterium tuberculosis, which usually infects the lungs, but also can spread to any part of the body including the kidney, spine, and brain. TB, if not treated properly, can even be fatal.1 The TB bacillus is typically spread through the air via respiratory droplets when a person with respiratory TB disease sneezes or coughs onto other individuals in close proximity.1,2

What is QuantiFERON®-TB Gold In-Tube?

An alternative to the tuberculin skin test (TST)

The QuantiFERON®-TB Gold In-Tube (QFT-G) is a blood test for use as an aid in diagnosing Mycobacterium tuberculosis infection (both latent tuberculosis infection and active tuberculosis disease).3 The test is approved by the U.S. Food and Drug Administration (FDA) for use with adult patients.

CDC Statement: 4

"The greater specificity of the Quantiferon test and the requirement for only one visit are compelling advantages."

CDC Specific Recommendations: 8 (June 2010)

  • Interference-Gamma Release Assays (IGRAs) may be used in place of (but not in addition to) a TST in all situations in which the CDC recommends TST as an aid in diagnosing M. tuberculosis infection.
  • IGRA is preferred for testing persons who have received BCG (as a vaccine or for cancer therapy).
  • IGRA is preferred for testing persons who have received BCG (as a vaccine or for cancer therapy).
  • An IGRA may be used in place of TST (without preference) to test recent contacts of persons with infectious tuberculosis with special considerations for follow-up testing. In contact investigations, negative results obtained prior to 8 weeks typically should be confirmed by repeat testing 8-10 weeks after the end of exposure.

How does QuantiFERON®-TB Gold In-Tube work?

The QFT-G is an indirect test for M. tuberculosis infection that is based on measurement of a cell-mediated immune response. A cocktail of 3 mycobacterial proteins (ESAT-6, CFP-10, and TB 7.7) stimulate the patient's T-cells in vitro to release interferon-gamma, which is then measured using ELISA technology. The test detects infections produced by the M. tuberculosis complex (including M. tuberculosis, M. bovis, and M. africanum infections). BCG strains and the majority of other non-tuberculosis mycobacteria do not harbor ESAT-6, CFP-10, and TB 7.7 proteins; thus, patients either vaccinated with BCG or infected with most environmental mycobacteria should test negative. Results should always be interpreted in conjunction with other clinical and laboratory findings.

What are the advantages of QuantiFERON®-TB Gold In-Tube over tuberculin skin test (TST)? 3

  • Improved specificity6
  • Results are not subject to reader bias
  • Results are not affected by the booster phenomenon (i.e., increased sensitivity on subsequent test, leading to false-positive results)
  • Accuracy is not affected by prior BCG (bacille Calmette-Guérin) vaccination
  • Requires only 1 patient visit (2-4 required for TST)
  • Cost savings from reduced staff time and avoidance of unnecessary follow-up testing and treatment5

Who developed QuantiFERON®-TB Gold In-Tube test?

Cellestis Limited, a listed Australian biotechnology company founded in 2000 in Melbourne, Australia, develops and manufactures the QuantiFERON®-TB Gold In-Tube test, a breakthrough blood test for the detection and control of tuberculosis. The QuantiFERON®-TB Gold technology is a patented method for detecting cell mediated immune (CMI) responses of T-cell lymphocytes using whole blood samples. QuantiFERON®-TB Gold test is available nationally through Quest Diagnostics.

The performance of the USA format of the QuantiFERON®-TB Gold IT test has not been extensively evaluated with specimens from the following groups of individuals:7

  1. Individuals who have impaired or altered immune function such as those who have HIV infection or AIDS, those who have transplantation managed with immunosuppressive treatment or others who receive immunosuppressive drugs (e.g. corticosteroids, methotrexate, azathioprine, cancer chemotherapy), and those who have other clinical conditions: diabetes, silicosis, chronic renal failure, hematological disorders (e.g., leukemia and lymphomas), and other specific malignancies (e.g., carcinoma of the head or neck and lung).
  2. Individuals younger than age 17 years.
  3. Pregnant women.

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References

1 CDC TB Basic Facts http://www.cdc.gov/tb/topic/basics/default.htm. Accessed 2/24/10.
2 World Health Organization. Tuberculosis Infection and Transmission http://www.who.int/mediacentre/factsheets/fs104/en/index.html. Accessed 3/1/10.
3 CDC Fact Sheet: QuantiFERONŽ-TB Gold Test. National Center for HIV/AIDS, Viral Hepatitis, and TB Prevention; Division of Tuberculosis Elimination (DTBE) Web site http://www.cdc.gov/tb/pubs/tbfactsheets/QFT.htm. Last reviewed April 18, 2007. Accessed October 5, 2007.
4 National Tuberculosis Controllers Association; Centers for Disease Control and Prevention (CDC). MMWR Recomm Rep. 2005;54(RR-15):1-47.
5 Lambert et al. Infection Control and Hospital Epidemiology. 2003; 24:814-820.
6 Diel et al. Evidence-based comparison of commercial interferon-gamma release assays for detecting active TB: a metaanalysis. Chest. 2010 Apr;137(4):952-68. Epub 2009 Dec 18.
7 FDA Device Approvals and Clearances Page: http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ DeviceApprovalsandClearances/Recently-ApprovedDevices/ucm084025.htm.
8 National Tuberculosis Controllers Association; Centers for Disease Control and Prevention (CDC). MMWR Recomm Rep. 2010;59 (RR-5): June 25, 2010.

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