Lab diagnosis of Mycobacterium leprae..!

1. presenter -
SANA ARMAN

2. HISTORY:

Leprosy or
Hansens disease.
Discovered in
1873 by G.H
Armauer Hansen.

3. CARDINAL SIGNS
• Numbness : hands & feet
• Painful and/or tender nerves
• Burning sensation in the
skin
• Painless swelling or lumps
in the face and earlobes
• Loss of eyebrows and or
eyelashes.

4. (a) Nodules on the face
(b) skin
patch on the face
(c) an enlarged
nerve in the neck

5. LAB DIAGNOSIS
OVERVIEW :
1. Specimens
2. Acid fast staining
3. Skin and nerve biopsy
4. Animal inoculation
5. Lepromin test

6. 1. SPECIMENS
Nasal mucosa, skin lesions, ear
lobules.
 Skin and nerve biopsy.

7. Edges of the lesion.
Slit and scrape
method:
• Pinch the site tight
• Incise
• Scrape & collect
material
• Smear on a slide
SKIN:

8. SKIN BIOPSY:
Active edges of the patches
NERVE BIOPSY :
From thickened nerves

9. 2. ACID FAST STAINING
 Ziehl-Neelson method
 Decolourising agent = 5% sulphuric acid
 Lepra cells confirm the diagnosis
of lepromatous
leprosy.

11. i. Bacteriological index
(B.I) :
Number of total bacilli in a tissue.
B.I is calculated by totalling the
grades and divided by no. of smears.
Minimum of 4 skin lesions,a nasal
swab & both the ear lobes are to be
examined.

15.  Percentage of uniformly stained
bacilli out of the total number of bacilli
counted.
For assessing the progress of
patients on chemotherapy.
ii. MORPHOLOGICAL
INDEX(M.I) :

16. • For histological
confirmation of
tuberculoid bacilli ( as
they cannot be
demonstrated in direct
smear)
• Skin biopsy is also useful
in diagnosis and
accurate classification of
leprosy lesion.
3. SKIN AND NERVE BIOPSY

17. Obligate intracellular parasite.
 Lacks many necessary genes for
independent survival.
WHY CAN’T WE CULTIVATE
Mycobacterium leprae
IN AN ARTIFICIAL CULTURE
MEDIUM???

18. 4. ANIMAL INOCULATION
 Nine banded armadillo
 Injection of ground tissue from
lepromatous nodules or nasal
scrapings from leprosy patient
into the foot pad of mice.
 Typical granuloma at the site of
inoculation within 6 months.

19. 5. LEPROMIN TEST
• Delayed type of hypersensitive reaction.
• First described by Mitsuda in 1919.
• Lepromins used as antigens may be of
human origin (lepromin H) or armadillo
derived (lepromin A).

20. Procedure :
 Carried out by the intradermal
injection of 0.1 ml of lepromin.

21. 1)Early reaction of
Fernandez
2)Late reaction of
Mitsuda
Biphasic response:

23. USES OF LEPROMIN TEST:
a) Classification of leprosy:
- Positive in tuberculoid leprosy
- Negative in lepromatous leprosy
b) Assessment of prognosis:
- Positive lepromin test indicates a good
prognosis.
- Negative lepromin test indicates a bad
prognosis.

24. c) Assessment of resistance:
- To assess the resistance of an individual to
leprosy.
- Resistance is indicated by positive
lepromin test.