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Mycobacteria

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this is a series of lectures on microbiology useful for both under and postgraduate medical and paramedical students

Published in: Health & Medicine, Technology

Mycobacteria

  1. 1. Dr. Ashish V. Jawarkar
  2. 2. Mycobacterium • Name from Myco and Bacteria, Fungus like bacteria • Because it forms mould like growth on liquid cultures Dr. Ashish V. Jawarkar
  3. 3. Mycobacteria that infect humans • M. Tuberculosis – TB • M. Leprae – Leprosy • Non tuberculous mycobacteria / atypical mycobacteria Dr. Ashish V. Jawarkar
  4. 4. Mycobacterium Tuberculosis • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  5. 5. Morphology • Neither gram positive, nor negative • Acid fast • They have mycolic acid in their cell wall which makes them acid fast • Difficult to decolorise with organic acids Dr. Ashish V. Jawarkar
  6. 6. Dr. Ashish V. Jawarkar
  7. 7. Dr. Ashish V. Jawarkar
  8. 8. Slightly curved rods Non motile Non capsulated Dr. Ashish V. Jawarkar
  9. 9. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  10. 10. Growth characteristics • • • • • Obligate aerobes Grow slowly – generation time 15 hours Colonies appear in two weeks Optimum temperature is 37 deg Solid media most commonly used – LJ media Dr. Ashish V. Jawarkar
  11. 11. Dr. Ashish V. Jawarkar
  12. 12. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  13. 13. Biochemical tests to differentiate MTB from atypical mycobacteria • Niacin test – – adding cyanogen bromide+aniline + ethanol = canary yellow color • Paranitrobenzoic acid – MTB cannot grow in presence of this • Catalase peroxidase test – MTB is weakly positive • Aryl sulfatase test – Negative for MTB Dr. Ashish V. Jawarkar
  14. 14. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  15. 15. Treatment and Resistance • DOTS – directly observed treatment shortcourse – HRZE for 4 months – HR for 2 months • H – isoniazid R – rifampicin Z - Pyrazinamide • E - Ethambutol Dr. Ashish V. Jawarkar
  16. 16. MDR-TB • Resistant to isoniazid and rifampicin XDR-TB • Resistant to all drugs Dr. Ashish V. Jawarkar
  17. 17. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  18. 18. Pathogenicity and virulence • Its pathogenicity is due to complex lipids like mycolic acid in cell wall.. This makes it – – – – – Acid fast Resistant to antibiotics Resistant to disinfectants like acid and alkalis Resistant to immune system Resistant to destruction by macrophages Dr. Ashish V. Jawarkar
  19. 19. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  20. 20. Epidemiology • Source – Humans with TB • Spread – droplet nuclei – inhaled • India – more than 40 percent population – that is nearly half of us are infected • Only saved due to our immunity • To stop TB – RNTCP – revised national tuberculosis control program has been started – offering DOTS to nearly 15 million patients daily – free of charge Dr. Ashish V. Jawarkar
  21. 21. Dr. Ashish V. Jawarkar
  22. 22. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  23. 23. Tuberculosis • Pulmonary • Extra pulmonary Dr. Ashish V. Jawarkar
  24. 24. Pulmonary Dr. Ashish V. Jawarkar
  25. 25. Dr. Ashish V. Jawarkar
  26. 26. Dr. Ashish V. Jawarkar
  27. 27. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  28. 28. Lab diagnosis • Sample – sputum for pulmonary, biopsy for extrapulmonary sites • Stain – Zn stain • Culture – LJ media • Raised ESR • PCR – polymerase chain reaction Dr. Ashish V. Jawarkar
  29. 29. Montoux test • PPD/tuberculin is injected into skin • Look for induration of skin Dr. Ashish V. Jawarkar
  30. 30. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  31. 31. Treatment • DOTS Dr. Ashish V. Jawarkar
  32. 32. Mycobacterium leprae Dr. Ashish V. Jawarkar
  33. 33. • Causes leprosy • Seen in developing countries like India only Dr. Ashish V. Jawarkar
  34. 34. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  35. 35. Dr. Ashish V. Jawarkar
  36. 36. • • • • Slightly curved rods Singly or in groups Cigar bundle appearance Lepra cells Dr. Ashish V. Jawarkar
  37. 37. Dr. Ashish V. Jawarkar
  38. 38. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  39. 39. Growth characteristics • Cannot be cultivated in vitro on any media • Grown in foot pad of armadillo Dr. Ashish V. Jawarkar
  40. 40. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  41. 41. Biochemical reactions • Cannot be grown.. • Cannot know biochemical reactions Dr. Ashish V. Jawarkar
  42. 42. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  43. 43. Resistance • Not known Dr. Ashish V. Jawarkar
  44. 44. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  45. 45. • ---- Dr. Ashish V. Jawarkar
  46. 46. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  47. 47. Epidemiology • • • • Human disease only Source – nasal secretions Entry – respiratory tract / skin Not highly communicable Dr. Ashish V. Jawarkar
  48. 48. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  49. 49. Diseases caused • • • • • Leprosy Affects skin and nerves Hypoaesthetic patch, thickened nerves Lion face, saddle nose, autoamputation Two main types – tuberculoid leprosy, lepromatous leprosy Dr. Ashish V. Jawarkar
  50. 50. Tuberculoid leprosy aka paucibacillary leprosy Dr. Ashish V. Jawarkar
  51. 51. Tuberculoid leprosy Dr. Ashish V. Jawarkar
  52. 52. Multibacillary leprosy/lepromatous leprosy Dr. Ashish V. Jawarkar
  53. 53. AUTO AMPUTATION Dr. Ashish V. Jawarkar
  54. 54. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  55. 55. Lab Diagnosis • Sample – biopsy from nasal mucosa, skin lesions, ear lobes • Stained with modified ZN stain – use 5% H2SO4 instead of 20% • Cannot be cultured Dr. Ashish V. Jawarkar
  56. 56. LEPROMIN TEST • Method is similar to tuberculin test • Injected antigen is lepromin • Reaction is read at – 48 hours – fernandez – 3-4 weeks - mitsuda Dr. Ashish V. Jawarkar
  57. 57. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment Dr. Ashish V. Jawarkar
  58. 58. • MDT Dr. Ashish V. Jawarkar
  59. 59. Treatment • Multi drug therapy consisting of – RIFAMPICIN – DAPSONE Dr. Ashish V. Jawarkar
  60. 60. Dr. Ashish V. Jawarkar
  61. 61. NOT COVERED • ATYPICAL MYOBACTERIA – Can be asked for short note – 5 marks Dr. Ashish V. Jawarkar
  62. 62. Dr. Ashish V. Jawarkar

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