Mycobacteria

1. Dr. Ashish V. Jawarkar

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

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

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

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

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

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

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

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

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

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

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

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

24. Pulmonary Dr. Ashish V. Jawarkar

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

31. Treatment • DOTS Dr. Ashish V. Jawarkar

32. Mycobacterium leprae Dr. Ashish V. Jawarkar

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

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

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

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

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

45. • ---- Dr. Ashish V. Jawarkar

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

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

51. Tuberculoid leprosy Dr. Ashish V. Jawarkar

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

53. AUTO AMPUTATION Dr. Ashish V. Jawarkar

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. 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

58. • MDT Dr. Ashish V. Jawarkar

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

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

Mycobacteria

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