Mycobacterium leprae.ppt for Medical students

Mycobacterium leprae.ppt for Medical students

1. MYCOBACTERIUM LEPRAE
Dr. Subhash Lal Karn, PhD
Associate Professor,
Microbiology Department
NGMC

2. INTRODUCTION
• Causative agent of Leprosy
• Vedic times (Kustha Roga) in Sushruta Samhita
and Biblical times in Middle East and
Hippocrates,460 BC
• G H Armauer Hansen (1873)in Norway
• Not possible to cultivate the bacillus in culture
media

3. MYCO.LEPRAE CELLS

4. MORPHOLOGY
• Straight or slightly curved rod
• 1- 8µm 0.2- 0.5µm
ˣ
• obligate intracellular pathogen
• Gram positive, less acid fast : 5% H2SO4
• Glia: bacilli bounded together by lipid like
substance : ‘Cigar bundle’ appearance
• Globi : masses of glia are known as globi
•Strict aerobe

5. MORPHOLOGY
• Virchow’s cells : cigar bundle of bacilli inside
lipid laden macrophages
•Undifferentiated histiocytes / foamy cells
• Morphological index: % of uniformly stained
bacilli in tissue : method of assessing pt’s
progress who is on chemotherapy.
• Bacteriological index : no. of bacilli in a tissue

7. CULTIVATION
• ICRC (Indian Cancer Research
Centre),Bombay (1962) : AFB isolated from
leprosy pts employing human foetal spinal
ganglion cell culture
• Shephard ( 1960) : Lepra bacilli can multiply
in footpads of mice at 20 C with development
of granuloma in 1-6 mnths

8. CULTIVATION
• Thymectomy done to inhibit CMI or
administration of antilymphocyte serum,
generalized inf is produced stimulating
Lepromatous Leprosy
• Nine banded armadilo : highly susceptible,
generalised inf with lepromatous leprosy
• Natural ds seen in Chimpanzees in west Africa
• Generation time : 12-13 days

9. NINE BANDED ARMADILO

10. RESISTANCE
• Warm climate : 9-16 days
• Moist soil : 46 days
• Direct sunlight : 2 hours
• UVL: 30 mins.

11. DEFINITION
•Leprosy is a chronic granulomatous disease of
humans, involving the skin, peripheral nerves,
nasal mucosa and any organ of the body

12. SOCIAL STIGMA
•Believed to be highly contagious ds
•Due to fear, ignorance, superstitious beliefs and
deformities – disfigurements causes social stigma
•Pts were considered UNCLEANE & out casted
•Today early diagnosis & effective treatment-
deformities can be prevented

13. •Incubation period:
•3-5yrs (vary between 2 & 40 yrs)
•Due to longer generation time
•Lepromatous leprosy has a longer generation time
than tuberculoid type

14. Madrid classification (1953)
Lepromatous
Dimorphous
Borderline
Indeterminate
Tuberculoid

15. Ridley and Jopling (1966)
TT BT BB BL LL
TT: Tuberculoid Leprosy
BT: Borderline Tuberculoid Leprosy
BB: Borderline Leprosy
BL: Borderline Lepromatous Leprosy
LL: Lepromatous Leprosy

16. INDIAN CLASSIFICATION
1981
•Lepromatous Type
•Borderline
•Indeterminate Type
•Pure Neurotic Type
•Tuberculoid Type

17. LEPROMATOUS LEPROSY -
MULTIBACILLARY
•Low host resistance
•Large no bacilli seen and globi seen inside the
macrophage
•superficial nodules – (Lepromata) : contain
granulation tissue and vacuolated cells , Lesions on
face : LEONINE face
•Nodules ulcerate, sec.infection, distortion and
mutilation
•Bacilli invade the mucosa of the nose, mouth & URT :
bacilli shed in nasal & oral secretions

18. LEPROMATOUS LEPROSY -
MULTIBACILLARY
•Nerve involvement : Very LATE
•RES, Eyes, Kidneys,testes,bones
•Bacillemia : common
•Humoral immune response broad & CMI deficient, poor
prognosis
•Antibodies in high titre against mycobacteria and Autoantibodies
: common
•Biological false positive reaction +ve
•Lepromin test : negative

19. Deformity of nose

20. LEPROMATOUS LEPROSY

21. TUBERCULOID LEPROSY :
PAUCIBACILLARY
• scanty bacilli in the lesions
•Few skin lesions : Sharply demarcated, annular
macular hypoigmented anaesthetic pathes,
Deformities in hands and feet
• Early neural involvement: common nerve :
ULNAR nr & Post-auricular nr (enlarged &
thickened)
• Medial popliteal nr: never involved

22. TUBERCULOID LEPROSY :
PAUCIBACILLARY
• Scanty bacilli in lesions
• Min. infectivity
• CMI adequate
• Lepromin test: positive
• Antimycobacterial antibodies - rare
• Autoantibodies – rare
• Good prognosis

23. Deformities of fingers

24. LESIONS OF TL.

25. BORDERLINE LEPROSY :
DIMORPHOUS
• Possess characteristics of TL and LL
• May shift to any one depending on
chemotherapy or alterations in host
resistance

26. INDETERMINATE
• Unstable : tissue reaction: no characteristics of
either LL or TT type
•One or two Hypopigmented patches & definite
sensory impairment
•Lesions : bacteriologically negative
• Spontaneous healing
• Some may progress to TT / LL

28. EPIDEMIOLOGY
• Humans : only source of inf (TL or LL)
• Mode of entry : RT or thr’ skin
• Asymptomatic inf quite common in endemic areas
• bacilli continue to shed from nose & skin for 2-3
yrs before S/S of ds seen in pt
• Not highly communicable ds
• I P : 2-5 yrs, as long as 30 yrs

29. •Direct contact: person to person
•Indirect contact: infected soil, fomites (cloths
& linens)
•Direct dermal inoculation during tattooing
•Environmental factors: rural areas, moist
soil, humidity, over crowding
•Males affected twice common than females

30. IMMUNITY
• High degree of innate immunity
exists in human beings
• Humoral & CMI
• Humoral Ab do not have harmful
effects on lepra bacilli

31. CMI
• Capable of destroying the bacilli
• Phagocytose the bacilli
• Sp.humoral antibodies absent
• Ig levels same
• Alb: Glob ratio is same
• Deficiency of CMI : deve LL

32. HUMORAL
• No deleterious effect on the bacilli
• Delayed hypersensitivity is absent
• Macrophages phagocytose the bacilli but do not kill
them
• Grow inside the cell

33. GENETIC EFFECT
•HLA- DR2 ---- in pts.with tuberloid

•HLA – MT1 & HLA- DQ1 --- LL

34. ROLE OF CMI IN CONTROL OF
LEPROSY
•People with low CMI: LL
•Delayed type of hypersensitivity: to lepra Ag
•Virchow’s Lepra Cell: macrophages unable to kill intracellular bacilli
but bacilli proliferate inside the cells
•Ag Specific: CMI deficient in LL pts, not susceptible to any
opportunistic infections
•CD4 & CD8 ratio: reverse (1:2) in LL, CD8 cells are prominent in
circulation & in granulomas
•Prominent T2H response: in LL pts: T2H specific cytokines: IL4,IL5, IL6
& IL10 leads to exaggerated Ab response so auto Ab common, False
+ve VDRL test

35. PEOPLE WITH INTACT CMI DEVELOP
TT
•DTH response: lepromine test positive
•CMI intact , prominent T1H response: release of T1H
specific cytokines like IL2, INF-γ which activates
macrophages
•CD4 & CD8 ratio: Normal, CD4 cells: seen in
circulation & in granulomas
• Normal humoral response

36. COMPLICATIONS
•Deformities: 25% untreated cases develop deformities, may due
to
•Nerve injury: ms weakness, paralysis
•Facial deformities or loss of eyebrows
•Infection or injury (ulcers)
•Common deformities:
•Face Leonine facies, sagging face, saddle nose & corneal opasity
•Hands: claw hand , wrist drop
•Feet: foot drop, clawing of toes, inversion of foot & planter ulcers

37. ACUTE EXACERBATIONS
•Type I : Lepra reaction
- In borderline
- Pts. on chemotherapy
- Influx of lymphocytes in lesion
- Shift to tuberculoid morphology
- Erythema & swelling
-Pain & tenderness
- CMI deficient: lesion may shift to Lepromatous pattern

38. •Type II ( Erythema Nodosum Leprosum)
•In LL & BL
•With few mnths. chemotherapy
•Tender, inflammed subcut. nodules appear with fever,
lymphadenopathy
•Arthur type response
•Dead cells

39. LEPROMIN TEST
•Mitsuda in 1919
•Skin test: delayed type of hypersensitivity test
•Ag lepromin : boiled,emulsified lepromatous
tissue rich in lepra bacilli , intradermal
injection of lepromin

40. LEPROMIN TEST
Biphasic reaction :
1. Fernandez reaction: erythema & induration
In 24-48 hrs and stays for 3-5 days
analogous to TT
2. Mitsuda reaction
Late reaction in 1-2 wks.
Peak in 1-4 wks. And then subsides, indurated nodule which
may ulcerate

42. LEPROMIN TEST
•Modern Ag – standardized
•Lepra bacillus content is 4 10 7
ˣ
Lbac./ml
•Std. lepromins from armadillo

43. INTERPRETATIONS
•Classify lesions of leprosy pts
•Assess prognosis & treatment
•Assess resistance of individuals to
leprosy

44. POSITIVE TEST
•Tuberculoid leprosy.
•Indicates a good prognosis.
•Indicates resistance to leprosy.
•Conversion of negative reaction to positive
reaction is the evidence of improvement.

45. NEGATIVE TEST
•Lepromatous leprosy.
•Bad prognosis.
•Poor resistance.

46. LAB.DIAGNOSIS
•Specimen from nasal mucosa,skin lesions and ear lobules
•Internal septum
•From 5-6 different areas
•Z-N staining

47. SMEAR GRADING
•1-10 bacilli in 100 fields = 1 +
•1-10 bacilli in 10 fields = 2 +
•1-10 bacilli in 1 field = 3 +
•1-100 bacilli per field = 4 +
•1-1000 bacilli in per field = 5 +
•More than 1000 bacilli,clumps and globi in
every field is 6 +

48. BACTERIOLOGICAL INDEX
•BI = Totaling no.of bacilli (live or
dead) seen /oil immersion field
total No.of smears examined
Min 4 skin lesions, a nasal swab, both the ear
lobes have to be examined

49. TREATMENT
•Dapsone 100 mg + rifampicin 600 mg
for 6 months ( for TT & BT)
Dapsone 100 mg
Rifampicin 600 mg for 2 years
Clofazime 50 mg

50. MYCOBACTERIUM LEPRAEMURIUM
•Rat leprosy.
•3-5 μm long, curved bacillus.
•Acid-fast, showing granular staining.
•Gram positive.

51. RAT LEPROSY
•Subcutaneus indurations.
•Lymphadenopathy.
•Ulcerations.
•Loss of hair.

52. CULTURE
•Chorioallantoic membrane of fertile hen’s egg.
•Tissue culture of rat fibroblast origin.
•Growth appears in 8 – 12 days.
•DNA study show no relation to M.leprae.