Diagnosis of tuberculosis


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Diagnosis of tuberculosis - Principles and Practice.

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Diagnosis of tuberculosis

  1. 1. DIAGNOSIS OFTUBERCULOSISPrinciples and Practice Dr.T.V.Rao.MD. Dr.T.V.Rao MD 1
  2. 2. Robert Koch Discovers Mycobacterium Dr.T.V.Rao MD 2
  3. 3. A Global Emergency The Tuberculosis in thebeginning of the 21st Centurydeclared as Global Emergency (WHO) Dr.T.V.Rao MD 3
  4. 4. Why Tuberculosis is a Important Disease. Tuberculosis continues to be a Important communicable disease. A leading cause of morbidity and mortality in Developing world. Most Important communicable disease in Bangladesh, China, Indonesia, Africa, and Pakistan. But it is Curable Disease Dr.T.V.Rao MD 4
  5. 5. Tuberculosis is a Global Problem Dr.T.V.Rao MD 5
  6. 6. Tuberculosis - Importantcommunicable disease spread by Respiratory route Dr.T.V.Rao MD 6
  7. 7. Why Everybody Concerned. Tuberculosis kills young adults. Premature death of the infected a prominent future. Today many are co infected with HIV. The open cases of Tuberculosis infects a few around his/her environment. A social burden to the family, society and Nations. Dr.T.V.Rao MD 7
  8. 8. Tuberculosis in the era of HIV / AIDS. HIV / AIDS epidemic led to large increase of Smear negativepulmonary tuberculosis which in turnhas led to poor treatment out comes, and early mortalityFrequently involves Lower lobes ofLungs. Dr.T.V.Rao MD 8
  9. 9. Why we fail to Diagnose Tuberculosis. Lack of health infrastructure. Control is plagued with lack of Accurate, Robust, and Rapid Diagnostic methods, Technologies. Dr.T.V.Rao MD 9
  10. 10. Why we failed ( Cont ) Diagnostic services are poor, and so we failed at Individual and community levels. Patients are diagnosed late. Many patients are never diagnosed before death. Early deaths are burden to Social Infrastructure and Economic loss. Dr.T.V.Rao MD 10
  11. 11. Importance of Clinical servicesEarly diagnosis rests with clinicians, whose contribution is immense in prompt treatment. A clinicians knowledge, proper documentation are immense help in Developing countries. Dr.T.V.Rao MD 11
  12. 12. When to suspect Tuberculosis Cough longer than 3 weeks. Fever for 1 month, or both. Blood stained sputum. Nigh sweats, weight loss Age between 14 and 70 years ( Correlates National Tuberculosis Programme ). Dr.T.V.Rao MD 12
  14. 14. Diagnosis. Tuberculosis is a diversified disease. Any organs can be involved. Any age group, gender no bar for Tuberculosis. Involvement of Lungs contribute to majority of tuberculosis. And involvement of Lungs is designated as Pulmonary tuberculosis. Dr.T.V.Rao MD 14
  15. 15. Diagnosis of Pulmonary Tuberculosis Majority of Adults suffer with pulmonary tuberculosis. Microbiological examination of Sputum continues to be a Gold standard in proving the Diagnosis. Sputum examination in Children is not sensitive in Diagnosis. Radiological examination of Lungs, most commonly prescribed investigation. Dr.T.V.Rao MD 15
  16. 16. X - ray examination of chest most easily available Investigation. Dr.T.V.Rao MD 16
  17. 17. Microbiological Investigations areessential for definitive Diagnosis of Tuberculosis. Dr.T.V.Rao MD 17
  18. 18. Importance of Optimal Specimens Pulmonary Tuberculosis is the commonest presentation of TuberculosisSputum is the Most important specimen for identification and isolation of Acid fast bacilli.The developing countries suffers the most important step in getting an ideal sample. Dr.T.V.Rao MD 18
  19. 19. Sputum Specimens**Train the staff to obtain the appropriate specimenA few minutes of education to patients on importance of ideal sample make a great difference and improves the Diagnosis. Dr.T.V.Rao MD 19
  20. 20. Observe to identify Sputum from Saliva. SPUTUM SALIVASpecimens appear Appears clear, watery, mucoid even, blood and frothy. stained. Contains many squamous epithelial Contains many cells Polymorphonutrophils. Absence of Polymorphoneutrophils. Dr.T.V.Rao MD 20
  21. 21. Role of Microscopy in Tuberculosis. Microscopy for Diagnosis of Tuberculosis is initiated in 1880 The conceptions have not changed since then. Best efforts should be put to obtain sputum, Processing of saliva loses all valuable clues to diagnose. Dr.T.V.Rao MD 21
  22. 22. Microscopy and Tuberculosis Microscopy with Ziehl – Neelsen’s staining A century old procedure Dr.T.V.Rao MD 22
  23. 23. Why Microscopy Only we need Microscope, and few stains. Most rapid, economical, Can detect bacterial load. A Diagnostic, and Prognostic tool. A little of sputum 0.2 µl is adequate. A prompt diagnosis after searching as few as 100 fields. Dr.T.V.Rao MD 23
  24. 24. Limitation of Microscopy for Tuberculosis. Repeated sample examinations. load on technical staff. Training and dedication of Microscopist. The load of bacilli must be more than 10,000 / 1 ml of sputum. Low in sensitivity < 50 % Repeated requests for samples High drop out by patients, for repeated samples. Not dependable in pediatric age group. Dr.T.V.Rao MD 24
  25. 25. Smear showing Acid Fast Bacilli. Dr.T.V.Rao MD 25
  26. 26. What is Smear Positivity WHO All patients who have submitted two Specimensand found to be positive for identification of AFB Dr.T.V.Rao MD 26
  27. 27. Processing Direct smear Negative specimens Sputum Microscopy can be improved with Sputum liquefaction, concentration and gravity sedimentation. Popular solvents Sodium hypochlorite. Sodium hydroxide. Ammonium Sulphate N-acetyl-L-cysteine –sodium hydroxide. Dr.T.V.Rao MD 27
  28. 28. Benefits of Liquefaction and Concentration Major studies showed processing of sputum with chemicals and centrifugation improved sensitivity up to 18 %. Incremental yield ( positive with bleach minus positives with Ziehl – Neelsen stain) up to 9 %. Treating specimens with Sodium hypochlorite is Mycobactericidal and also kills HIV and improves the safety and acceptability by technical staff. Dr.T.V.Rao MD 28
  29. 29. When Microscopy fails Smear negative tuberculosis. In HIV infected patients, on many occasions prove negative. in spite of presence of bacilli, ( as few bacilli are expectorated). Needs concentration and liquefaction with chemicals. Time consuming, needs more technical manpower Dr.T.V.Rao MD 29
  30. 30. Growing role of Fluorescent Microscopy There is a growing need for screening for AFB by Florescent Microscopy. Several studies prove, Florescent Microscopy in Diagnosis of Tuberculosis is a priority, Developing world should opt and initiate florescent microscopy. Dr.T.V.Rao MD 30
  31. 31. Acid Fast Bacilli as seen under Fluorescent Microscope Dr.T.V.Rao MD 31
  32. 32. Why we need Florescent Microscopy Useful when few bacilli are present. Increases the sensitivity in HIV patients with tuberculosis. Reduces the time needed for testing. About 15 times as many fields of view can be scanned by fluorescent microscopy than by Ziehl – Neelsen’method in the same period. Increases the sensitivity by 10 % Better conclusions with one or two specimens, unlike Ziehl Neelsen’s method needing 3 or > 3 specimens. Dr.T.V.Rao MD 32
  33. 33. Culturing Mycobacterium Culturing for isolation of Mycobacterium spp continues to be a Gold standard, particularly in Developing countries. Need only 10 – 100 bacilli / 1 ml of sputum. Dr.T.V.Rao MD 33
  34. 34. Culturing Most useful in Surveillance, Drug sensitivity testing patterns. Identify treatment failures. Useful in Patients presenting with respiratory symptoms, X- ray’s suggestive, but smear negative. Can prove culture positive. Cultures remain suggestive and helpful in early treatment periods, failed drug regimes. Dr.T.V.Rao MD 34
  35. 35. Methods of Culturing. Culturing on Lowenstein Jenson’s culture medium remain the affordable ,economical method in developing world. Dr.T.V.Rao MD 35
  36. 36. Limitation in Culturing Mycobacterium spp are slow growing. Need 6 – 8 weeks for growing. Specimens can be contaminated while growing, needs repeated specimens, in turn patients loose confidence in Laboratories. Dr.T.V.Rao MD 36
  37. 37. Recent facts on Culturing Useful in HIV infected patients with Tuberculosis. As even few bacilli can be grown in spite of smear negativity. But the specimens to be incubated for longer time as few bacilli are present. Dr.T.V.Rao MD 37
  38. 38. Pitfalls in Culturing Specificity is lost due to contamination. Can yield false positive results in 1 – 4 % of the cases. Cultures may be negative in spite of x rays are suggestive of tuberculosis. Dr.T.V.Rao MD 38
  39. 39. Growth of Acid fast bacilli on L J Medium. Dr.T.V.Rao MD 39
  40. 40. ADVANCES IN CULTURING TECHNIQUES.There are emerging Modern Media with accurate detection, arereplacing the Egg and Agar based medium. Dr.T.V.Rao MD 40
  41. 41. Emerging methods in Culturing MGIT – Mycobacterium growth incubator tube method. Growth occurs in shorter than egg medium. Usefulness in HIV patients established. Contamination is less But expensive to people in Developing world. Dr.T.V.Rao MD 41
  42. 42. Blood culturing for Mycobacterium Useful in HIV patients, and children. Effective in isolation of Atypical mycobacterium. But not cost effective. May be important tool in future for diagnosing Tuberculosis in HIV infected. Dr.T.V.Rao MD 42
  43. 43. Molecular Methods inDiagnosis of Tuberculosis Several methods are available, mainly used as Research tools Dr.T.V.Rao MD 43
  44. 44. Real Time PCR replacing older Methods Dr.T.V.Rao MD 44
  45. 45. PCR How useful to our Patients? PCR ( Polymerase chain reaction ) used by several investigators. However most cases can be diagnosed with simple methods if effectively used. The definite role of PCR continues to be controversial Above all not cost effective to Developing countries. Dr.T.V.Rao MD 45
  46. 46. Rapid DiagnosticMethods in Tuberculosis Past decade has seen several emerging technologies How far practicable ? Dr.T.V.Rao MD 46
  47. 47. Emerging Rapid Methods. 1. Fast Plaque TB uses phage amplificationtechnology.2. ELISA ( QuantiFERON – TB )3. Enzyme-Linked immunospot ( ELISPOT ) ELISPOT proved highly useful to detect active tuberculosis in Adults and children. Dr.T.V.Rao MD 47
  48. 48. Emerging Technology MODS Microscopic observation drug susceptibility assay. ( MODS ) A new method gained importance in several reviews. Use a tissue culture plate based assay with use of Middle Brook 7HG. Needs a inverted light microscope. Even the drug resistance can be tested with Rifampicin, and Isoniazid. Safe to work with cultures. Dr.T.V.Rao MD 48
  49. 49. Non Specific Tests Tuberculin test ( Mantoux Test ) Dr.T.V.Rao MD 49
  50. 50. Tuberculin Test ( Mantoux Test ) Test to be interpreted in relation to clinical evaluation. Even the induration of 5 mm to be considered positive when tested on HIV patients. Lacks specificity. Dr.T.V.Rao MD 50
  51. 51. Serology in Tuberculosis. Several serological methods were evaluated. But never gained the acceptance of the majority of the clinicians. Serological tests are low sensitivity. Many physicians depend on serology in extra pulmonary tuberculosis. Dr.T.V.Rao MD 51
  52. 52. Dealing with Tuberculosis In HIV / AIDS patients. Diagnosing Tuberculosis in HIV infected is a priority and improve quality of Life Dr.T.V.Rao MD 52
  53. 53. HIV/AIDS - Tuberculosis Consider the HIV status Identify the severity of Tuberculosis. Early use of chest radiography. Maximal number of sputum smear examinations. Sputum concentration methods to be encouraged even by smaller laboratories. Explore the use of Florescent Microscopy. All smear negative specimens should be cultured. Dr.T.V.Rao MD 53
  54. 54. Limitations of Rapid Tests The testing needs advanced and sophisticated infrastructure. These tests are known for their inability to diagnose between active disease and latent infection. Exclusively used in Developed nations. Dr.T.V.Rao MD 54
  55. 55. Extra Pulmonary Tuberculosis Poses several challenges, Yet no optimal, specificdiagnostic methods Dr.T.V.Rao MD 55
  56. 56. Extra pulmonary Tuberculosis A real challenge to Clinicians and Laboratories. Optimal specimen collection a priority, Molecular Methods are growing need. Clinicians start drug regimes on empirical basis. Several serological tests for antibody determinations are evaluated. Dr.T.V.Rao MD 56
  57. 57. Identification of Atypical Mycobacterium A growing concern on infections with less known, uncommon Mycobacterium in immunosuppressed, an emerging infectious disease. Dr.T.V.Rao MD 57
  58. 58. Atypical Mycobacterium Needs the help of reference laboratories. Needs different drug regimes, unlike typical Mycobacterium isolates. Now a gowning concern in the era of AIDS. Dr.T.V.Rao MD 58
  59. 59. Future perceptions It is highly essential to explore and discover rapid, simple, and accurate tuberculosis diagnostic tools. A massive investment, greater scientific interest, political commitment a top priority, Man power development, Human resource utilization a greater concern. Microscopy and Florescent Microscopy utilization should be immediate concern, and strengthening of treatment initiation protocols. Effective methods in diagnosing smear negative patients a growing priority. Dr.T.V.Rao MD 59
  60. 60. GeneXpert MTB/RIF The Xpert MTB/RIF is a cartridge-based, automated diagnostic test that can identify Mycobacterium tuberculosis (MTB) and resistance to rifampicin (RIF). It was co-developed by Cepheid, Inc. and Foundation for Innovative New Diagnostics, with additional financial support from the US National Institutes of Health (NIH) and technical support from the University of Medicine and Dentistry of New Jersey Dr.T.V.Rao MD 60
  61. 61. How the test works The Xpert MTB/RIF detects DNA sequences specific for Mycobacterium tuberculosis and rifampicin resistance by polymerase chain reaction It is based on the Cepheid GeneXpert system, a platform for rapid and simple-to-use nucleic acid amplification tests (NAAT). Dr.T.V.Rao MD 61
  62. 62. How the test works The Xpert® MTB/RIF purifies, concentrates, amplifies (by real-time PCR) and identifies targeted nucleic acid sequences in the Mycobacterium tuberculosis genome, and provides results from unprocessed sputum samples in 90 minutes, with minimal biohazard and very little technical training required to operate Dr.T.V.Rao MD 62
  63. 63. Microscopy in Tuberculosis TODAYIn spite ofseveralscientific, andmolecularadvancesMicroscopy inTuberculosiscontinues tobe back bonein Diagnosis. Dr.T.V.Rao MD 63
  64. 64. For Article of Current Interest Visit me on Dr.T.V.Rao MD 64
  65. 65. Programme Created byDr.T.V.Rao MD for Medical and Paramedical Professionals Email doctortvrao@gmail.com Dr.T.V.Rao MD 65
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