Mycobacterium lepreae by Dr. Rakesh

1. By Dr. Rakesh Prasad Sah
Associate Professor, Microbiology

2. • Leprosy: chronic mycrobacterial disease of ancient world
 still affecting many parts of world  maily Asia and Africa
• Leprosy  Kushta Roga in Sushruta Samhita, 600 BC.
• Caused by Mycobacterium leprae  first observed by
Hansen in 1868.
• First bacterial pathogen of human to described  it still
remains least understood  not possible to grow in artificial
culture medium.

3. • slender, slightly curved or straight bacillus.
• acid-fast, but less than tubercle bacillus  5% H2SO4 is
used.
• Intracellular & extracellular, single or in group in cells 
present as bundles bound together by lipid like substance 
‘glia’ &  these masses are known as “globi”.
• Parallel rows of bacilli in globi  give appearance of ‘Cigar
bndle’
ZN-
Staining
Uniform &
Solid
Fragmente
d &
granular
Dead
Bacilli
Live
Bacilli
Help to
monitor
efficacy
of the
treatme
nt

4. • slender, slightly curved or straight bacillus.
• acid-fast, but less than tubercle bacillus  5% H2SO4 is
used.
• Intracellular & extracellular,single or in group.in cells 
present as bundles bound together by lipid like substance 
‘glia’ &  these masses are known as “globi”.
• Parallel rows of bacilli in globi  give appearance of ‘Cigar
bndle’
ZN-
Staining
Uniform &
Solid
Fragmente
d &
granular
Dead
Bacilli
Live
Bacilli
Help to
monitor
efficacy
of the
treatme
nt

5. • Have not yet been grown on artificial culture media or
tissue culture.
• The most important animals used for experimental
infection with M. leprae include mouse and nine-banded
armadillos.
• Nine banded armadillo.
• Foot pad of mouse at low temp(200cafter inoculation 
granuloma devlop at the site in 1—6 mths. if CMI depressed
(administration of antilymphocytic serum or thymectomy), 
generalised infection resembling L.L.
• Armadillo  L.L.

6. • One of best report from ICRC (Indian Cancer Research Institute)
acid fast bacilli isolated from leprosy patients  employing human
foetal spinal ganglion cell culture.
• Other Animals
• Chimpanzees
• Monkeys
• Indian Pangolin
• Golden hamster
• Chipmunks

7. • Cell wall 4 layers. Inner  peptidpglycan  shape & rigidity
external to this is lipoarabinomannan—B (LAM-B),
attach to this is mycolic acid layer. outermost layer’s major
component is phenolic glycolipid-1(PGL-1). LAM-B, PGL-1—
used for serodignosisPGL-1supress CMI.
• 18kda, 28kda,----

8. • Chronic granulomatous disease.
• Bacilli localize primarily in the
• Skin
• Peripheral nerves
• Nasal Mucosa
• Tissue or organ may be involved
• Source
• infected patients.
• Mode of transmission
• droplets
• skin lesions.
• I.P.—Long, Variable.
Preference Of
Bacilli
Lower
Temperature
Superficial &
Cooler
Tissues

9. • Types
• Lepromatous,
• Tuberculoid
• Diamorphous
• Indeterminate
• CMI status-determines type.
• Indeterminate occupies position between L.L. & T.T.
• Type of leprosy changes with chemotheraopy &
alternation in immune status.

10. • Seen in individuals  either CMI is low or absent.
• Severe form & poor prognosis.
• More infectious, Lepromin negative  deficient CMI.
• High conc. of humoral abs  No protective role.
• Develops nodular lesion on
• Face
• Ear lobes
• Hand
• Feet
• Less commonly on trunk

11. • Is slow and symmetric thickening of peripheral nerves &
anesthesia
• As a result of loss of sensation  nodules ulcerate &
secondary infection occur  distortation & mutilation of
extremities.
• Multibacillary.
• Skin lesions  contain many macrophages  packed
with bacilli.
• Lepra bacilli present in large no. in
• Skin lesions
• Mucosa of nose
• Mouth
• Upper respiratory tract
• Bacilli shed in
• Sweat
• Nasal
• Oral secretions.

12. • Localised form of disease  CMI good.
• few skin lesions  Non elevated hypo or hyper
pigmented macular patches involving
• Face
• Limbs
• Trunk
• Bacilli  very few of absent  tissues.
• Lepromin positive  intact CMI
• abs. rarely produced.
extend into
big nerve
trunks
Involvement
of local
nerves
become
thickened,
hard and
tender
lead to
deformities
of limbs

13. Feature Lepromatous
leprosy
Tuberculoid
Leprosy
Lepra Bacilli in
lesion
Numerous Scanty
CMI Deficient / absent Adequate
Lepromin test Negative Positive
Infectivity Highly infectious Usually non
infective
Mycobacterial
Antibodies
Abundant Rarely produced

14. • Lesion resembels TL but bacteriological &
immunological picture is of LL.
• Shifting of the form to any of the two extreme type
depends upon chemotherapy & alteration in immune
status of host.

15. • Neither characteristic of TT nor LL.
• Lesions in the form of maculoanashthetic patches.
• Type 1 Reaction (Reversal Reaction)
• seen in borderline patient who developed CMI and shift toward
tuberculoid spectrum.
• It may lead to permanent nerve damage.
• This is due to DTH.
• Type 2 ( erythema nodosum leprosum)
• seen in LL patients under treatment.
• This is due to formation of Ag-Ab complexes.
• Clinically crops of red nodules appears on skin which last for 1-2 days.

16. Characters TT BT BB BL LL
Bacilli in the skin - +/- + ++ +++
Nasal secretion - - - + +++
Granulomma formation +++ ++ + - -
Lepromin Test +++ - +/- - -
Ab to M. Leprae +/- +/- + ++ +++

17. • First described by Mitsuda in 1919.
• Original lepromin antigen- boiled, emulsified, lepromatous
tissue rich in lepra bacilli.
• Nowadays, Lepromin-A or Lepromin-H.
• Are of 2 types-
• 1) Integral Antigen
• 2) Bacillary Lepromin.

18. • Procedure  0.1ml intradermal.
• Biphasic response
• Early reaction of Fernandez  erythema & induration in 24-48 hrs,
remains for 3-5 days. Histologicaly  serous exudates with
lymphocytic infiltration.
• Late reaction of Mitsuda  appears after 1-3 wks of injection and
peak in 4wks  reaction the form of nodule-may ulcerate.
Histologically  infiltration with lymphocytes, epitheloid, giant
cells.
• Mitsuda indicates resistance to leprosy.

19. • Classification of leprosy.
• Assessment of prognosis.
• Assessment of resistance.(field workers)

20. • Specimen : Nasal Mucosa, skin lesions, & ear lobules.
• The specimens from skin are obtained by “slit and scrape”
method.
• Skin- six diff areas including
• buttocks
• chin
• cheek,
• forehead
• ears.
Smear on slide
Air dry & fix
Stain (ZN-
Pinch the Sight
Scrape & Collect
material
Incise

21. • AFB staining
• Grading-
• 1-10 in 100 fields ---- 1+
• 1-10 in 10 fields----- 2+
• 1-10 per field--------3+
• 10-100 per field-----4+
• 100-1000 per field---5+
• More than 1000 bacilli, clumps & globi in every field = 6+

22. • Bacteriological Index:-
• Defined as number of total bacilli in tissue.
• Calculated by grades (number of pluses, +s) scored in all smears divided
by no. of smears taken.
• E.g. if 7 smears examined  have total of 14+  BI will be 2.
• For calculation minimum of
• 4 skin lesions
• nasal swab and
• both ear lobes examined.
• Morphological Index
• Defined as percentage of uniformly stained bacilli out of total no. of bacilli
counted.
• Useful for assessing chemotherapy

23. • Animal inoculation
• Lepromin test: - not diagnostic but to assess prognosis
and response to treatment.
• Serological test: Anti PGL-1 Antibodies detection. High
titer in LL and LOW in TL.

24. • Chemotherapy : Dapsone.
Emergence of Dapsone resistance hence WHO
recommended MDT.
• Immunotherapy:
Efforts to induced effective CMI by IV inj of transfer factor,
and extract of lymphocytes from patients suffering from
TL etc.
• Administration Of Vaccine: