Diagnosis Of Pulmonary Tb

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Diagnosis Of Pulmonary Tb

  1. 1. Diagnosis of Pulmonary Tuberculosis Presenter: 4A Ri 范綱志 Sep. 29,2008
  2. 2. Why diagnosis important? <ul><li>Diagnosis of tuberculosis in most cases </li></ul><ul><ul><li>clinical diagnosis based upon the clinical presentation (hx & PE) </li></ul></ul><ul><li>In 15-20% of p’t with suspected TB </li></ul><ul><ul><li>lab confirmation never obtained </li></ul></ul><ul><li>Early diagnosis and initiation of effective therapy </li></ul><ul><ul><li>reducing morbidity and mortality from TB </li></ul></ul><ul><ul><li>minimize the spread of infection </li></ul></ul>
  3. 3. Outline <ul><li>Screening for prior infection </li></ul><ul><ul><li>Tuberculin skin test </li></ul></ul><ul><li>Diagnosis of pulmonary TB </li></ul><ul><ul><li>Medical history </li></ul></ul><ul><ul><li>Physical examination </li></ul></ul><ul><ul><li>Chest radiograph </li></ul></ul><ul><ul><li>Bacteriologic exam </li></ul></ul>
  4. 4. Screening for prior infection Tuberculin skin test 篩出感染者
  5. 5. Screening for prior infection <ul><li>Whom to screen </li></ul><ul><ul><li>High prevalence and high risk population (HIV) </li></ul></ul><ul><li>How to screen </li></ul><ul><ul><li>Mantoux tuberculin test (ie, purified protein derivative or PPD, tuberculin skin test) </li></ul></ul><ul><li>How to interpret </li></ul><ul><ul><li>Determine maximum diameter of induration by palpation </li></ul></ul>
  6. 6. Mantoux Tuberculin Test <ul><li>Preferred method of testing for TB infection in adults and children </li></ul><ul><li>Tuberculin skin testing useful for </li></ul><ul><ul><li>Examining person who is not ill but may be infected </li></ul></ul><ul><ul><li>Determining how many people in group are infected </li></ul></ul><ul><ul><li>Examining person who has symptoms of TB </li></ul></ul>
  7. 7. Mantoux test <ul><li>Inject intradermally 0.1 ml of 5TU PPD tuberculin </li></ul><ul><li>Produce wheal 6 mm to 10 mm in diameter </li></ul><ul><li>Represent DTH (delayed type hypersensitivity) </li></ul>
  8. 8. Reading of Mantoux test <ul><li>Read reaction 48-72 hours after injection </li></ul><ul><li>Measure only induration </li></ul><ul><li>Record reaction in mm </li></ul>
  9. 9. Classifying the tuberculin reaction <ul><li>> 5 mm is classified as positive in </li></ul><ul><ul><li>HIV-positive persons </li></ul></ul><ul><ul><li>Recent contacts of TB case </li></ul></ul><ul><ul><li>Persons with fibrotic changes on CXR consistent with old healed TB </li></ul></ul><ul><ul><li>Patients with organ transplants and other immunosuppressed patients </li></ul></ul>
  10. 10. Classifying the tuberculin reaction <ul><li>>10 mm is classified as positive in </li></ul><ul><ul><li>Recent arrivals from high-prevalence countries </li></ul></ul><ul><ul><li>Injection drug users </li></ul></ul><ul><ul><li>Residents and employees of high-risk settings </li></ul></ul><ul><ul><li>Mycobacteriology laboratory personnel </li></ul></ul><ul><ul><li>Persons with clinical conditions that place them at high risk </li></ul></ul><ul><ul><li>Children <4 years, or children and adolescents exposed to adults in high-risk categories </li></ul></ul>
  11. 11. Classifying the tuberculin reaction <ul><li>> 15 mm is classified as positive in </li></ul><ul><ul><li>Persons with no known risk factors for TB </li></ul></ul>
  12. 12. Factors may affect TST <ul><li>False negative </li></ul><ul><ul><li>Faulty application </li></ul></ul><ul><ul><li>Anergy </li></ul></ul><ul><ul><li>Acute TB (2-10 wks to convert) </li></ul></ul><ul><ul><li>Very young age (< 6 months old) </li></ul></ul><ul><ul><li>Live-virus vaccination </li></ul></ul><ul><ul><li>Overwhelming TB disease </li></ul></ul><ul><li>False positive </li></ul><ul><ul><li>BCG vaccination (usually <10mm by adulthood) </li></ul></ul><ul><ul><li>Nontuberculous mycobacteria infection </li></ul></ul>
  13. 13. Boosting <ul><li>Some people with LTBI may have negative skin test reaction when tested years after infection </li></ul><ul><li>Initial skin test may stimulate (boost) ability to react to tuberculin </li></ul><ul><li>Positive reactions to subsequent tests may be misinterpreted as a new infection </li></ul>
  14. 14. Two-Step Testing <ul><li>Use two-step testing for initial skin testing of adults who will be retested within 1-3 weeks </li></ul><ul><ul><li>If first test (+), consider the person infected </li></ul></ul><ul><ul><li>If first test (-), give second test 1-3 weeks later </li></ul></ul><ul><ul><li>If second test (+), consider person infected </li></ul></ul><ul><ul><li>If second test (-), consider person uninfected </li></ul></ul>
  15. 15. Screening for prior infection <ul><li>台灣早年結核病盛行率高 </li></ul><ul><li>50 年前 20 歲以上成人 </li></ul><ul><ul><li>80% TST 為陽性 </li></ul></ul><ul><li>年齡越大 ,TST 對結核病的診斷幫助越小 </li></ul>
  16. 16. Diagnosis of Pulmonary TB
  17. 17. Diagnosis of disease <ul><li>Medical history </li></ul><ul><li>Physical examination </li></ul><ul><li>Chest radiograph </li></ul><ul><li>Bacteriologic exam </li></ul><ul><ul><li>AFS </li></ul></ul><ul><ul><li>Culture </li></ul></ul>
  18. 18. Medical History
  19. 19. Medical History <ul><li>Symptoms of disease </li></ul><ul><li>History of TB exposure, infection, or disease </li></ul><ul><li>Past TB treatment </li></ul><ul><li>Demographic risk factors for TB </li></ul><ul><li>Medical conditions that increase risk for TB disease </li></ul>
  20. 20. Medical History <ul><li>High prevalence population </li></ul><ul><ul><li>More likely to be exposed to and infected with bacillus </li></ul></ul><ul><ul><ul><li>Immigrant from high prevalence area </li></ul></ul></ul><ul><ul><ul><li>Resident or worker in jail </li></ul></ul></ul><ul><ul><ul><li>Long term care facility </li></ul></ul></ul><ul><ul><ul><li>Close contact to p’t with active TB </li></ul></ul></ul>
  21. 21. Medical History <ul><li>High risk population </li></ul><ul><ul><li>More likely to progress from infection to active TB </li></ul></ul><ul><ul><ul><li>HIV (+) or other immunodeficiency </li></ul></ul></ul><ul><ul><ul><li>CRF </li></ul></ul></ul><ul><ul><ul><li>DM </li></ul></ul></ul><ul><ul><ul><li>IVDA </li></ul></ul></ul><ul><ul><ul><li>Alcoholics </li></ul></ul></ul><ul><ul><ul><li>Malnourished </li></ul></ul></ul><ul><ul><ul><li>Malignancy </li></ul></ul></ul><ul><ul><ul><li>Gastrectomy </li></ul></ul></ul>
  22. 22. Physical Examination
  23. 23. Physical Examination <ul><li>Productive, prolonged cough </li></ul><ul><ul><li>duration of ~ 3 weeks‏ </li></ul></ul><ul><li>Chest pain </li></ul><ul><li>Hemoptysis </li></ul><ul><li>Fever/Chills </li></ul><ul><li>Night sweats </li></ul><ul><li>Appetite loss </li></ul><ul><li>Weight loss </li></ul><ul><li>Easily fatigued </li></ul>
  24. 24. Chest radiography
  25. 25. Chest radiography <ul><li>Classical radiograph appearance </li></ul><ul><ul><li>Infiltration </li></ul></ul><ul><ul><li>Cavitation </li></ul></ul><ul><ul><li>Fibrosis with traction </li></ul></ul><ul><ul><li>Enlargement of hilar and mediastinal lymph node </li></ul></ul><ul><li>In reactivaiton TB </li></ul><ul><ul><li>Classically fibrocavitary apical disease </li></ul></ul><ul><li>Primary TB </li></ul><ul><ul><li>Middle or lower lobe consolidation </li></ul></ul>
  26. 26. Chest radiography <ul><li>Abnormalities often seen in apical or posterior segments of upper lobe or superior segments of lower lobe </li></ul><ul><li>May have unusual appearance in HIV-positive persons </li></ul><ul><li>Cannot confirm diagnosis of TB!! </li></ul>cavity in patient‘s RUL classic&quot; for adult-type, reactivation tuberculosis
  27. 27. Classic adult TB CXR <ul><li>PA view </li></ul><ul><ul><li>diffuse parenchymal disease with multiple cavities and bulla formation on the left </li></ul></ul><ul><ul><li>Sputum smear was positive for AFB </li></ul></ul>
  28. 28. Chest radiography <ul><li>No chest X-ray pattern is absolutely typical of TB </li></ul><ul><li>10-15% of culture-positive TB patients not diagnosed by X-ray </li></ul><ul><li>40% of patients diagnosed as having TB on the basis of x-ray alone do not have active TB </li></ul>
  29. 29. X-ray-based evaluation causes over-diagnosis of TB NTI, Ind J Tuberc, 1974 Over- diagnosis
  30. 30. Bacteriologic Exam
  31. 31. Specimen Collection <ul><li>Obtain 3 sputum specimens for smear examination and culture </li></ul><ul><li>Persons unable to cough up sputum </li></ul><ul><ul><li>induce sputum </li></ul></ul><ul><ul><li>bronchoscopy </li></ul></ul><ul><ul><li>gastric aspiration </li></ul></ul><ul><li>Follow infection control precautions during specimen collection </li></ul>
  32. 32. Three Specimens <ul><li>Three specimens optimal </li></ul><ul><ul><li>Spot specimen on first visit; sputum container given to patient </li></ul></ul><ul><ul><li>Early morning collection by patient on next day </li></ul></ul><ul><ul><li>Spot specimen during second visit </li></ul></ul>
  33. 33. Three sputum smears are optimal
  34. 34. Number of sputum samples required <ul><li>overall diagnostic yield for sputum examination related to </li></ul><ul><ul><li>the quantity of sputum (at least 5 mL) </li></ul></ul><ul><ul><li>the quality of sputum </li></ul></ul><ul><ul><li>multiple samples obtained at different times to the laboratory for processing </li></ul></ul><ul><ul><ul><li>3 samples obtained at least eight hours apart with at least one sample obtained in the early morning </li></ul></ul></ul>
  35. 35. Number of sputum samples required <ul><li>several studies have suggested that only two samples may be sufficient to capture the majority of cases: </li></ul><ul><ul><li>Retrospective study </li></ul></ul><ul><ul><ul><li>Nelson, SM, Deike , MA, Cartwright, CP. Value of examining multiple sputum specimens in the diagnosis of pulmonary tuberculosis. J Clin Microbiol 1998; 36:467. </li></ul></ul></ul><ul><ul><ul><ul><li>overall, 92 percent of cases would have been detected with two specimens </li></ul></ul></ul></ul><ul><ul><ul><li>Craft, DW, Jones, MC, Blanchet , CN, et al. Value of examining three acid-fact bacillus sputum smears for the removal of patients suspected of having tuberculosis from the &quot; airborn precautions&quot; category. J Clin Microbiol 2000; 38:4285. </li></ul></ul></ul><ul><ul><ul><ul><li>a third sputum smear was of no additional value </li></ul></ul></ul></ul>
  36. 36. Smear Examination <ul><li>Strongly consider TB in patients with smears containing acid-fast bacilli (AFB)‏ </li></ul><ul><li>Results should be available within 24 hours of specimen collection </li></ul><ul><li>Presumptive diagnosis of TB </li></ul><ul><li>Not specific for M. tuberculosis </li></ul>
  37. 37. AFB Smear <ul><li>Sensitivity: 40-70% </li></ul><ul><li>Specificity: 90% </li></ul>
  38. 38. AFB smear AFB (shown in red) are tubercle bacilli
  39. 39. Reporting on AFB Microscopy Number of bacilli seen Result reported None per 100 oil immersion fields Negative 1-9 per 100 oil immersion fields Scanty, report exact number 10-99 per 100 oil immersion fields 1+ 1-10 per oil immersion field 2+ > 10 per oil immersion field 3+
  40. 40. Proportion of patients with pulmonary TB who have positive AFB smears AFB positivity in TB patients 0 10 20 30 40 50 60 70 HIV Negative Early HIV Late HIV
  41. 41. Open tuberculosis <ul><li>A tuberculous ulceration or other form of tuberculosis in which tubercle bacilli are present in the excretions or secretions . </li></ul><ul><li>Pulmonary tuberculosis, especially with cavitation. </li></ul><ul><li>開放性結核就是在病人咳出的痰液中有結核桿菌的存在 </li></ul>
  42. 42. Cultures Colonies of M. tuberculosis growing on media <ul><li>Gold standard for TB diagnosis </li></ul><ul><li>Use to confirm diagnosis of TB </li></ul><ul><li>Culture all specimens, even if smear negative </li></ul><ul><li>Results in 4 to 14 days when liquid medium </li></ul><ul><li>systems used </li></ul>
  43. 43. Cultures <ul><li>Sensitivity: 80-85% </li></ul><ul><li>Specificity: 98% </li></ul><ul><li>Times needed: </li></ul><ul><ul><li>Solid medium </li></ul></ul><ul><ul><ul><li>4-8 wks </li></ul></ul></ul><ul><ul><li>Liquid medium </li></ul></ul><ul><ul><ul><li>2 wks </li></ul></ul></ul>
  44. 44. AFB smear vs. Cultures <ul><li>AFB smear </li></ul><ul><ul><li>可檢測到每 ml 標本有 5000-10000 隻細菌 </li></ul></ul><ul><ul><li>染色陰性並不能排除結核病 </li></ul></ul><ul><ul><li>Rapid diagnosis </li></ul></ul><ul><li>Cultures </li></ul><ul><ul><li>每 ml 標本只需有 10-100 隻細菌便可檢測到 </li></ul></ul><ul><ul><li>More sensitive </li></ul></ul><ul><ul><li>Allows drug susceptivity test </li></ul></ul>
  45. 45. Microscopy is more objective and reliable than X-ray Inter-observer agreement
  46. 46. Microscopy is a more specific test than X-ray for TB diagnosis Specificity
  47. 47. Diagnosis of Pulmonary TB Cough 3 weeks AFB X 3 Broad-spectrum antibiotic 10-14 days If symptoms persist, repeat AFB smears, X-ray If consistent with TB Anti-TB Treatment If 1 positive , X-ray and evaluation If 2/3 positive : Anti-TB Rx If negative :
  48. 48. Diagnosis of pulmonary TB
  49. 49. Recommended Diagnostic Approach
  50. 50. Take Home Message <ul><li>診斷結核病必須綜合 </li></ul><ul><ul><li>臨床表現 </li></ul></ul><ul><ul><ul><li>Non-specific symptoms </li></ul></ul></ul><ul><ul><li>放射學變化 </li></ul></ul><ul><ul><ul><li>Often over diagnosis </li></ul></ul></ul><ul><ul><li>實驗室細菌學診斷 </li></ul></ul><ul><ul><ul><li>AFB smear </li></ul></ul></ul><ul><ul><ul><ul><li>Rapid diagnosis, presumptive diagnosis </li></ul></ul></ul></ul><ul><ul><ul><li>Culture </li></ul></ul></ul><ul><ul><ul><ul><li>Gold standard, more sensitive </li></ul></ul></ul></ul><ul><li>只要強烈懷疑 TB 可先開始進行抗結核治療 </li></ul>
  51. 51. Source <ul><li>UpToDate, Diagnosis of pulmonary tuberculosis, 2008, John Bernardo,MD </li></ul><ul><li>行政院衛生署疾病管制局 , 結核病診治指引 , Taiwan Guidelines on TB Diagnosis & Treatment, Edition 3, 主編陸坤泰 </li></ul>
  52. 52. Thanks for your attention!

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