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TB- QUANTIFERON TEST.pptx
- 1. QuantiFERON-TB Gold Medical LaboratoryScientist Decca College Of Health And Allied Science Ayoub Julai Nyanje
- 2. • QuantiFERON-TB Gold(QFT) is a simple blood test that aids in the detection of Mycobacterium tuberculosis, the bacteria which causes tuberculosis (TB). • QFT is an interferon-gamma (IFN-γ) release assay, commonly known as an IGRA, and is a modern alternative to the tuberculin skin test Tuberculin skin tests (TST), Purified protein derivative PPD or Mantoux). Unlike the TST, • QFT is a controlled laboratory test that requires only one patient visit and is unaffected by previous Bacille Calmette-Guerin (BCG) vaccination.
- 3. • QFT ishighly specific and sensitive: a positive result is strongly predictive of true infection with M. tuberculosis. However, like the TST and other IGRAs, • QFT cannot distinguish between active tuberculosis disease and latent tuberculosis infection, and is intended for use with risk assessment, radiography, and other medical and diagnostic evaluations. Like any diagnostic aid, QFT cannot replace clinical judgment.
- 4. • The USCenters for Disease Control (CDC) Guidelines recommend the use of IGRAs in all situations in which the TST was historically used, with Interferon-Gamma Release Assays (IGRAs), being the preferred test for persons who have been BCG vaccinated or are unlikely to return for TST reading.
- 5. The QFT advantage– three tubes, one clear result QFT uses unique blood collection tubes that enable immediate exposure of viable blood lymphocytes to highly specific TB antigens (ESAT- 6/CFP-10/TB-7.7(p4)) and test controls coated on the inner surface of the tubes. Antigen exposure produces a quantifiable immune response to aid in the diagnosis of TB infection.
- 6. • Nil tube Negativecontrol to adjust for background IFN-γ • TB Antigen tube To detect the CD4+ T cell responses to TB antigens • Mitogen tube Low response may indicate inability to generate IFN-γ
- 7. QFT is themost clinically tested and proven IGRA. • QuantiFERON-TB Gold is the most clinically tested and proven IGRA available.More than 30 million QFT tests have been sold across 130+ countries, including more than 7 million in 2015. Trust the only blood test for TB infection that offers • The most accurate and reproducible results for TB infection • The confidence of more than 1200 clinical and scientific studies • Convenient and objective ELISA technology • Single visit testing
- 8. QFT has simpleblood collection and convenient workflow • QFT employs whole blood collection to make T cell incubation simple and fast. After blood collection, the sample must be incubated, which can occur on-site or at the testing laboratory, providing your practice with complete flexibility and convenience.
- 10. Benefits of theQuantiFERON technology • Use of whole blood in QFT makes T cell incubation simple and fast, and reduces labor • No tedious lymphocyte isolation, washing, counting, diluting, or culturing • Technology designed for clinical screening of large sample numbers, providing the standards, controls, and assay reproducibility needed for clinical diagnosis
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- 12. Specimen collection i. Collectmore than 3.5ml (Venous blood) in a heparin tube . ii. After blood collection it should be stored at room temperature iii. Within 16 hours after collection dispense 1ml into each TB-feron with micro pipette iv. as soon as tube is filled with blood, shake it 10times gently or use a Roller- rocker to allow the entire surface of the tube to be immersed in blood so that blood and antigen on tube wall can be mixed well
- 13. Standard operating procedurefor performing QuantiFERON-TB Procedure 1. Collect blood in well labeled green top tube with Lithium 2. Pipette 1ml (1000ul) of blood to red top tube ,purple top tube and grey top tube. 3. Mix (10 times) or by using roller for 5minutes 4. Incubate for 16-24hrs at 37oC 5. Centrifuge for 4500 RPM for 15min 6. Switch on machine SD-Bionsor 7. Select Patient ID following adding patient name then place start
- 14. Steps cont… 8. Bringthe test devices and Tablets pellets to room temperature since they stored in refrigerator (2-8oC 9.Pippete 100ul of sample (plasma) into tube with tablets pellets gently mixing to avoid formation of bubbles 10. The machine will instruct the user to insert the test device with barcode point upward ,the machine will scan the device to ensure validity and then test will partially ejected leaving the sample well opened 11. First tube with gray top will be displayed ,the mixture off pellets from step 9 will be pipetted and poured into sample well then click start , repeat procedure from step 9 to 11 for the next tubes
- 15. • 11. waitfor the results (15 minutes ) • Reporting of results i. Negative ii. Positive iii. In determinant (with comment report sample collection after 2 weeks)
- 16. NOTE • Plasma samplesshould only be harvested using a pipet. • After centrifugation, avoid pipetting up and down or mixing plasma by any means prior to harvesting. At all times, take care not to disturb material on the surface of the gel • Plasma samples can be loaded directly from centrifuged blood collection tubes into the QFT ELISA plate, including when automated ELISA workstations are used. • Plasma samples can be stored for up to 28 days at 2°C to 8°C or, if harvested, below –20°C for extended periods • For adequate test samples, harvest at least 150 µl of plasma.
- 17. Source of errorsto patient results • Fail to follow standard operating procedure • Incompetence of the personnel • Poor specimen collection technique • Incubation of three tubes at wrong temperature • Using expired kit devices • Poor storage of three tube
- 18. Reference • https://www.quantiferon.com/products/quantiferon-tb-gold/ • Centersfor Disease Control and Prevention. (2010) Updated guidelines for using interferon-gamma release assays to detect Mycobacterium tuberculosis infection — United States. MMWR 59(RR05), 1.