Mycobacteria

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

1. Dr. Ashish V. Jawarkar

2. Dr. Ashish V. Jawarkar
Mycobacterium
•Name from Myco and
Bacteria, Fungus like
bacteria
•Because it forms mould
like growth on liquid
cultures

3. Dr. Ashish V. Jawarkar
Mycobacteria that infect humans
•M. Tuberculosis – TB
•M. Leprae – Leprosy
•Non tuberculous mycobacteria / atypical
mycobacteria

4. Dr. Ashish V. Jawarkar
Mycobacterium Tuberculosis
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

5. Dr. Ashish V. Jawarkar
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

6. Dr. Ashish V. Jawarkar

7. Dr. Ashish V. Jawarkar

8. Dr. Ashish V. Jawarkar
Slightly curved rods
Non motile
Non capsulated

9. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

10. Dr. Ashish V. Jawarkar
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

11. Dr. Ashish V. Jawarkar

12. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

13. Dr. Ashish V. Jawarkar
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

14. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

15. Dr. Ashish V. Jawarkar
Treatment and Resistance
•DOTS – directly observed treatment
shortcourse
–HRZE for 4 months
–HR for 2 months
•H – isoniazid R – rifampicin Z - Pyrazinamide
•E - Ethambutol

16. Dr. Ashish V. Jawarkar
MDR-TB
•Resistant to isoniazid and rifampicin
XDR-TB
•Resistant to all drugs

17. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

18. Dr. Ashish V. Jawarkar
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

19. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

20. Dr. Ashish V. Jawarkar
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

21. Dr. Ashish V. Jawarkar

22. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

23. Dr. Ashish V. Jawarkar
Tuberculosis
•Pulmonary
•Extra pulmonary

24. Dr. Ashish V. Jawarkar
Pulmonary

25. Dr. Ashish V. Jawarkar

26. Dr. Ashish V. Jawarkar

27. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

28. Dr. Ashish V. Jawarkar
Lab diagnosis
•Sample – sputum for pulmonary, biopsy for
extrapulmonary sites
•Stain – Zn stain
•Culture – LJ media
•Raised ESR
•PCR – polymerase chain reaction

29. Dr. Ashish V. Jawarkar
Montoux test
•PPD/tuberculin is injected into skin
•Look for induration of skin

30. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

31. Dr. Ashish V. Jawarkar
Treatment
•DOTS

32. Dr. Ashish V. Jawarkar
Mycobacterium leprae

33. Dr. Ashish V. Jawarkar
•Causes leprosy
•Seen in developing countries like India only

34. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

35. Dr. Ashish V. Jawarkar

36. Dr. Ashish V. Jawarkar
•Slightly curved rods
•Singly or in groups
•Cigar bundle appearance
•Lepra cells

37. Dr. Ashish V. Jawarkar

38. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

39. Dr. Ashish V. Jawarkar
Growth characteristics
•Cannot be cultivated in vitro on any media
•Grown in foot pad of armadillo

40. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

41. Dr. Ashish V. Jawarkar
Biochemical reactions
•Cannot be grown..
•Cannot know biochemical reactions

42. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

43. Dr. Ashish V. Jawarkar
Resistance
•Not known

44. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

45. Dr. Ashish V. Jawarkar
•----

46. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

47. Dr. Ashish V. Jawarkar
Epidemiology
•Human disease only
•Source – nasal secretions
•Entry – respiratory tract / skin
•Not highly communicable

48. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

49. Dr. Ashish V. Jawarkar
Diseases caused
•Leprosy
•Affects skin and nerves
•Hypoaesthetic patch, thickened nerves
•Lion face, saddle nose, autoamputation
•Two main types – tuberculoid leprosy,
lepromatous leprosy

50. Dr. Ashish V. Jawarkar
Tuberculoid leprosy
aka paucibacillary leprosy

51. Dr. Ashish V. Jawarkar
Tuberculoid leprosy

52. Dr. Ashish V. Jawarkar
Multibacillary leprosy/lepromatous
leprosy

53. Dr. Ashish V. Jawarkar
AUTO AMPUTATION

54. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

55. Dr. Ashish V. Jawarkar
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

56. Dr. Ashish V. Jawarkar
LEPROMIN TEST
•Method is similar to tuberculin test
•Injected antigen is lepromin
•Reaction is read at
–48 hours – fernandez
–3-4 weeks - mitsuda

57. Dr. Ashish V. Jawarkar
•Morphology
•Growth characteristics
•Biochemical reactions
•Resistance
•Pathogenicity and virulence
•Epidemiology
•Diseases caused
•Laboratory diagnosis
•Treatment

58. Dr. Ashish V. Jawarkar
•MDT

59. Dr. Ashish V. Jawarkar
Treatment
•Multi drug therapy consisting of
–RIFAMPICIN
–DAPSONE

60. Dr. Ashish V. Jawarkar

61. Dr. Ashish V. Jawarkar
NOT COVERED
•ATYPICAL MYOBACTERIA
–Can be asked for short note – 5 marks

62. Dr. Ashish V. Jawarkar