Tuberculin testing

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Tuberculin testing

  1. 1. TUBERCULIN SKIN TESTING MANTOUX TUBERCULIN SKIN TEST Dr.T.V.Rao MDDR.T.V.RAO MD 1
  2. 2. TUBERCULOSIS: PRIMARY INFECTION• 95% of cases begin with pulmonary focus• usually a SINGLE focus• hypersensitivity develops 2 to 6 weeks • until then, focus may grow larger • hypersensitivity brings caseation
  3. 3. PRIMARY INFECTION: LYMPHO-HEMATOGENOUS SPREAD• 8-14 weeks after onset of TB• usually occult• Mantoux positive during this phase• body wide seeding occurs during this phase • bone, kidney, meninges etc. • 3% of children with nl CXR’s develop calcifications in lung apices (SIMON FOCI)
  4. 4. USUAL PROGRESSION OF PRIMARY INFECTION infection Lympho-hematogenous spread healed PRIMARYDR.T.V.RAO MD infection 4
  5. 5. PROGRESSIVE PRIMARY DISEASE lymph node involvement cavitationpleural effusion DR.T.V.RAO MD 5
  6. 6. TUBERCULIN SKIN TESTING • The Mantoux tuberculin skin test (TST) is the standard method of determining whether a person is infected with Mycobacterium tuberculosis. Reliable administration and reading of the TST requires standardization of procedures, training, supervision, and practice.DR.T.V.RAO MD 6
  7. 7. DIAGNOSIS OF LATENT TB WITH THE TUBERCULIN SKIN TESTThe issues:• Applying the tuberculin skin test• Reading the test• Interpreting the test – including in children• Management of positive TSTDR.T.V.RAO MD 7
  8. 8. INDICATIONS FOR SKIN TEST SCREENING• Persons with signs and/or symptoms suggestive of tuberculosis disease• Recent contacts of persons known or suspected to have tuberculosis• Persons with undiagnosed upper lobe fibrotic lesions• Persons infected with HIV• Alcoholics and intravenous drug abusers• Persons with medical conditions known to increase the risk of disesase if infection has occurred: • silicosis, gastrectomy, jejunoileal bypasss, significant weight loss below IBW, chronic renal failure, diabetes mellitus, high dose corticosteroid treatment or other immunosuppressive therapy, leukemia, lymphoma, malignancy• Groups at high risk of infection: • Latin America, Oceana, medically underserved populations, residents of long term care facilities• Groups that would pose a significant risk to others if diseased: employees of health care facilities, schools, child care facilitiesATS/CDCDR.T.V.RAO MD 8
  9. 9. THE TB SKIN TEST: MATERIALS • OLD TUBERCULIN • culture of TB bacillus in glycol peptone broth • TB “tine” test • PURIFIED PROTEIN DERIVATIVE (PPD) • TB bacillus grown in Long’s media, filtered after heating • adopted by WHO as standard in 1950 • PPD-S 1952 • dose = 5 IUDR.T.V.RAO MD 9
  10. 10. THE TB (MANTOUX) SKIN TEST• Intra-dermal • quality control important • trained practioner necessary• Delayed hypersensitivity • cell mediated • 48-72 hours• False negative • immuno-compromized conditions • measles/measles immunizations• Nonspecific reactions • increase >10 IU • cross reactions, atypical MBDR.T.V.RAO MD 10
  11. 11. APPLYING THE TUBERCULIN SKIN TEST Courtesy of Dr. Marc Steben11 Dr.T.V.Rao MD
  12. 12. APPLYING THE TUBERCULIN SKIN TEST12 Dr.T.V.Rao MD
  13. 13. REACTION TO THE TUBERCULIN SKIN TEST Courtesy of Dr. Marc Steben 13 Dr.T.V.Rao MD
  14. 14. READING THE TUBERCULIN SKIN TEST Courtesy of Dr. Marc Steben14 Dr.T.V.Rao MD
  15. 15. READING THE TUBERCULIN SKIN TEST• Read 2-3 days after placing the test• Feel for induration• Color change without induration is not included in the measurement• Use a ruler or calipers• Have someone else check if unsure• Always document the exact size (mm) – not just “positive” or “negative”DR.T.V.RAO MD 15
  16. 16. A POSITIVE SKIN TEST ONLY INDICATES• A positive TB skin test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease.DR.T.V.RAO MD 16
  17. 17. READING THE SKIN TESTING IN TUBERCULOSIS • The reaction should be measured in millimetres of the induration (palpable, raised, hardened area or swelling). The reader should not measure erythema (redness). The diameter of the indurated area should be measured across the forearm (perpendicular to the long axis).DR.T.V.RAO MD 17
  18. 18. PRIMARY INFECTION: LYMPHO-HEMATOGENOUS SPREAD• 8-14 weeks after onset of TB• usually occult• Mantoux positive during this phase• body wide seeding occurs during this phase • bone, kidney, meninges etc. • 3% of children with nl CXR’s develop calcifications in lung apices (SIMON FOCI)
  19. 19. READING THE TUBERCULIN SKIN TEST• Read 2-3 days after placing the test• Feel for induration• Color change without induration is not included in the measurement• Use a ruler or calipers• Have someone else check if unsure• Always document the exact size (mm) – not just “positive” or “negative”DR.T.V.RAO MD 19
  20. 20. FACTORS CAUSING DECREASED ABILITY TO RESPOND TO TUBERCULIN• Factors related to the person being tested • Infections • Viral (measles, mumps, chickenpox) • Bacterial (typhoid fever, brucelosis, typhus, pertussis, overwhelming TB, • Fungal (South American blastomycosis) • Live virus vaccinations (MMR) • Metabolic derangements (chronic renal failure) • Nutritional factors (severe protein depletion) • Diseases affecting lymphid organs (Hodgkin’s lymphoma, chronic lymphocytic leukemia, sarcoidosis) DR.T.V.RAO MD 20
  21. 21. FACTORS CAUSING DECREASED ABILITY TO RESPOND TO TUBERCULIN (CONTD) • Drugs (corticosteroids, other immunosuppressive agents) • Age (newborn, elderly) • Recent overwhelming infection with M. tuberculosis • Stress (surgery, burns, mental illness, graft versus host reactions)• Factors related to the tuberculin used• Factors related to the method of administration• Factors related to reading the test and recording resultsDR.T.V.RAO MD 21
  22. 22. MILIARY DISEASE GENERALIZED HEMATOGENOUS TUBERCULOSIS• generalized dissemination through bloodstream • caseous focus ruptures into blood vessel • growth of tubercle within the blood vessel • may be acute, occult or chronic• uniformly fatal if not treated• rare• usually occurs in the first 4 months after primary infection DR.T.V.RAO MD 22
  23. 23. MILIARY Disease• millet seed appearance on X-ray• Mantoux positive?• Most children still have active primary complex when miliary disease strikes• most develop meningitis
  24. 24. EVALUATION OF A PATIENT WITH POSITIVE TST Evaluate for active TB • Re-check symptoms and exam – cough, fever, weight loss, enlarged lymph nodes, dyspnea • Chest X-ray, if possibleDR.T.V.RAO MD 24
  25. 25. • Programme Created by Dr.T.V.Rao MD for Medical and Health Care Workers in the Developing World • Email • doctortvrao@gmail.comDR.T.V.RAO MD 25

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