TB Frequently Asked Description Performance Questions

1 References General Tuberculosis throughOxfordDiagnosticsLaboratories Control ProgramsContact InvestigationsReferencesFrequently AskedQuestions Table of Contents General Tuberculosis InformationTuberculosis: Definition, Infection and Disease1. What is the scale of the TB problem?2. How is TB spread?3. What is TB infection (Latent Tuberculosis Infection LTBI or latentTB )?4. What is TB disease ( active TB )?5. Are certain groups of individuals at an increased risk of exposureto mycobacterium tuberculosis?6. Are certain individuals at an increased risk of progressing fromlatent TB infection to TB disease?7. How important is treatment for TB disease?8. Why is the treatment period for TB disease so long?

2 9. How important is treatment for TB infection ( LTBI or latent TB )?TB Detection10. Is there a test for the detection of TB infection( LTBI or latent TB )? Tuberculin Skin Test (TST) Interferon-Gamma Release Assays (IGRA)11. Is there a test for the detection of TB disease ( active TB )?12. What are the limitations of the TST?Bacille Calmette-Gu rin (BCG) Vaccination13. What is the BCG vaccination? Test Description and Performance14. What is the intended use of the test?15. Why does the test measure interferon-gamma?16. Does the test differentiate between latent TB infectionand TB disease?17. What data is there to support the test in clinical use?18. How soon after exposure to mycobacterium tuberculosis can aninfection be detected with the test?

3 Test Performance Characteristics19. What is the sensitivity and the specificity of the test?20. Why is sensitivity important in a test for Mycobacteriumtuberculosis infection?21. Why is specificity important in a test for Mycobacteriumtuberculosis infection?22. Can the test be used in testing samples from patientswith weakened immune systems?23. Are any patient groups excluded from testing with test?24. Is a positive test result expected in patients with a previous history of tuberculosis?25. Are infections with mycobacteria other than mycobacterium tuberculosis expected to produce positive test results? 26. Can the test detect infections of drug-resistant tuberculosis strains such as MDR-TB, XDR-TB or TDR-TB?

4 27. What regulatory approvals does the test have?28. Is the test affected by previous BCG vaccination? Advantages over Tuberculin Skin Test29. What are the advantages of the test?30. What are the advantages of the test over TST?31. Can the test be used in place of a TST? Testing through Oxford Diagnostic LaboratoriesOrdering and cost32. Which requisition form should be used?33. How much does the test cost?Blood Collection34. How are test samples collected?35. How much blood is needed for the test?36. Which blood collection tubes can be used?37. Can blood collection tubes containing EDTA (purple top tubes) be used?38. Do you accept other types of specimens other than blood?

5 39. What information is required on the blood collection tube?40. How should blood samples be stored prior to sending to the laboratory?41. After collecting a blood sample, how long do I have to send it to the laboratory?42. In which circumstances would the laboratory reject a blood sample?Specimen Packaging and Shipping43. How should samples be packaged?44. How can additional supplies be ordered ( requisition forms)?45. Where can samples be sent for processing using the test?46. How are samples shipped to the laboratory?47. Can I ship samples using my own carrier?48. How can I obtain the dangerous goods training needed to conform to IATA Packaging Instructions 650?

6 49. When can samples be sent to Oxford Diagnostic Laboratories?Laboratory Certification50. Is Oxford Diagnostic Laboratories CLIA-certified?51. What does College of American Pathologists (CAP) accreditation mean?52. Is Oxford Diagnostic Laboratories CAP-accredited?53. Is the test covered by insurance? Test Results54. How will I receive test results?55. How are test results interpreted?56. How are test results reported?57. What action should be taken if the test is positive?58. What is a borderline result?59. Are borderline test results the same as invalid results?60. What should I do with a borderline test result?61. What should I do with an invalid test result?

7 62. What is the expected frequency of invalid results with the test?63. Why does the test include a Positive Control with each patient sample?64. Why does the test include a Nil (Negative) Control with each patient sample?65. How quickly are test results available? Methodology66. How do I prepare blood samples for the test?67. How is the test performed?68. Are all the materials required for the test provided in the kit?69. How many tests (patient samples) can be processed with the 8 kit?70. What is the T-Cell Xtend reagent and how is it used?71. How long can blood samples be stored prior to processing with the T-Cell Xtend reagent?72. Does the T-Cell Xtend reagent impact test Performance ?

8 73. Is a standard curve required each time the test is performed?74. Which buffer should be used for washing the 96-well plate for the test?75. What is the purpose of the cell washing and counting steps in the test?76. Can finished assay plates be stored for future reading?77. Is there a dedicated product support service for laboratories?Screening Control Programs78. What is the impact of TB testing on healthcare resources?Contact Investigations79. In contact investigations, should a baseline test be performed?ReferencesTuberculosis: Definition, Infection and DiseaseGeneral Tuberculosis InformationGeneral Tuberculosis Information1 What is the scale of the Tuberculosis (TB) problem?

9 Although effective treatment has been available for over 70 years, TB is the leading cause of death from an infectious disease worldwide. The World Health Organization (WHO) estimates that more than one-third of the world s population is infected with mycobacterium tuberculosis. TB continues to be a significant disease due to factors such as immigration, the emergence of drug-resistant TB strains, HIV, and other conditions that weaken the immune system. REFERENCE: 11 General Tuberculosis Information2 How is Tuberculosis (TB) spread? TB is passed from person to person through the air. Individuals with pulmonary (lung) TB can propel aerosols containing mycobacterium tuberculosis complex organisms into the air when they cough, sneeze, sing, speak or spit.

10 Persons who then inhale these aerosols can become infected. Factors that determine the probability of infection include the immune status of the exposed individual, infectiousness of the TB contact and the proximity, frequency and duration of exposure. REFERENCE: 22 General Tuberculosis Information3 What is TB infection (Latent Tuberculosis Infection LTBI or latent TB )? Individuals with TB infection ( LTBI or latent TB ) harbor dormant mycobacterium tuberculosis complex organisms in their bodies but are not infectious and do not have symptoms of TB disease. TB infected individuals usually have a positive test result; however, assessing the probability of infection requires a combination of epidemiological, historical, medical and diagnostic findings.