M leprae -its structure and bichemistry

1. STRUCTURE OF
MYCOBACTERIUM
LEPRAE

2. • Discovered by Gerhard
Armauer Hansen in
1873 , Norwegian
physician.
• First bacterium- causing
disease in humans.

3. • Hansen - born in Bergen and got his degree in
university of Oslo.
• With Daniel Cornelius Danielssen, he did the study of
leprosy.
• In 1879 he gave tissue samples to Albert Neisser who
stained the bacteria & announced his findings in 1880.
• Hansen as discoverer of the bacillus and Neisser as
identifier of it as the etiological agent.
• Neisser put in some effort to downplay the assistance
of Hansen.
• Hansen’s distinguished work was recognized at the
International Leprosy Congress held at Bergen in 1909.
• Hansen had suffered from syphilis since the 1860s but
died of heart disease

4. • Cultured -Mouse foot
pads of nine-banded
armadillos.(Dasypus
novemcinctus)

6. CHARACTERISTICS
• Family- Mycobacteriaceae.
• Schizomycete ; order- Actinomycetales
• Intracellular parasite – macrophages.
• Gross Morphology-
straight / curved slender
Capsulated
Non-motile

7. Non sporing
Acid fast
Rod – 1 to 8u in length
0.2 to 0.5u in width
Appear fragmented or beaded
• Cells stain homogeneously;(altered and dead)
• Divides by binary fission

9. • Non cultivable; cultured only on footpad of
Nine Banded Armadillos.
• Possesses enzyme phenol oxidase.
• Bound together like cigar bundles by lipid like
substances – Glia.
• Only Mycobacterium – infecting peripheral
nerves.

10. • Resistence-
 9 -16 days in warm humid climate.
46 days in moist soil.
2 hours in sunlight
30 minutes in UV rays

11. ULTRASTRUCTURE
• Components-
1. Capsule
2. Cell wall
3. Cell membrane
4. Cytoplasm

12. CAPSULE
• Electron transparent zone of foamy or vesicular
material
• 2 capsular lipids- (a) phthicerol demycocerosate.
(b)phenolic glycolipid-1
• Protects bacteria- lysosomal enzymes &
metabolites.
• Present in Urine and serum, helps in early
diagnosis.

13. CELL WALL
• Outer and inner layer
• 20nm thick
• Consists of cross linked peptidoglycan attached to
arabinogalactan polymer.
• Outer layer-
Lipopolysaccharides & lipopolysaccharides-
protein complexes
Electron lucent

15. • Inner layer-
Peptidoglycan
Electron dense
• Cell wall proteins form a major target of T cell
immunogenicity.
• Mediates the uptake of nutrients into
mycobacterium.
• Last structure to disappear with
chemotheraphy.

16. CELL MEMBRANE
• Responsible for transport of molecules inside
and out of the organism
• Composed of lipids & proteins
• LIPIDS- phospholipids
• PROTEINS- MMP-I & MMP II

17. CYTOPLASM
• Consist of storage granules, DNA, RNA.
• Concerned with translation and multiplication
• Gel electrophoresis separates these 3 major
proteins

19. CLINICAL APPILICATION
• PCR technique for DNA amplification – high
degree sensitivity
• PCR – sensitive method for detecting small
number of M.leprae.
• Reverse transcriptase-PCR tecnique useful to
detect live and dead bacteria

20. SUMMARY
• Mycobacteiaceae.
• Straight/ slightly curved slender, capsulated,
non motile ,non sporing, acid fast.
• Binary fission.
• Cultured- footpad – nine banded armadillos.
• Glia.
• Infect peripheral nerves.

21. • Capsule- electron transparent
2 capsular lipids- (PDIM & PGL -1)
• Cell wall- 2 layers.
• Cell membrane-responsible for molecules into
and out membrane.
• Cytoplasm- Contains DNA, RNA, storage
granules.

22. THANK YOU