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STRUCTURE OF
MYCOBACTERIUM
LEPRAE
• Discovered by Gerhard Armauer Hansen in 1873 , Norwegian physician.
• First bacterium- causing disease in humans.
• Hansen - born in Bergen and got his degree inuniversity of Oslo.
• With Daniel Cornelius Danielssen, he did the study ofleprosy.
• In 1879 he gave tissue samples to Albert Neisser whostained the bacteria & announced his findings in 1880.
• Hansen as discoverer of the bacillus and Neisser asidentifier of it as the etiological agent.
• Neisser put in some effort to downplay the assistanceof Hansen.
• Hansen’s distinguished work was recognized at theInternational Leprosy Congress held at Bergen in 1909.
• Hansen had suffered from syphilis since the 1860s butdied of heart disease
• Cultured -Mouse foot pads of nine-banded armadillos.(Dasypusnovemcinctus)
CHARACTERISTICS
• Family- Mycobacteriaceae.
• Schizomycete ; order- Actinomycetales
• Intracellular parasite – macrophages.
• Gross Morphology-
straight / curved slender
Capsulated
Non-motile
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
• Non cultivable; cultured only on footpad ofNine Banded Armadillos.
• Possesses enzyme phenol oxidase.
• Bound together like cigar bundles by lipid likesubstances – Glia.
• Only Mycobacterium – infecting peripheralnerves.
• Resistence-
9 -16 days in warm humid climate.
46 days in moist soil.
2 hours in sunlight
30 minutes in UV rays
ULTRASTRUCTURE
• Components-
1. Capsule
2. Cell wall
3. Cell membrane
4. Cytoplasm
CAPSULE
• Electron transparent zone of foamy or vesicularmaterial
• 2 capsular lipids- (a) phthicerol demycocerosate.
(b)phenolic glycolipid-1
• Protects bacteria- lysosomal enzymes &metabolites.
• Present in Urine and serum, helps in earlydiagnosis.
CELL WALL
• Outer and inner layer
• 20nm thick
• Consists of cross linked peptidoglycan attached toarabinogalactan polymer.
• Outer layer-
Lipopolysaccharides & lipopolysaccharides-protein complexes
Electron lucent
• 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.
CELL MEMBRANE
• Responsible for transport of molecules insideand out of the organism
• Composed of lipids & proteins
• LIPIDS- phospholipids
• PROTEINS- MMP-I & MMP II
CYTOPLASM
• Consist of storage granules, DNA, RNA.
• Concerned with translation and multiplication
• Gel electrophoresis separates these 3 majorproteins
CLINICAL APPILICATION
• PCR technique for DNA amplification – highdegree sensitivity
• PCR – sensitive method for detecting smallnumber of M.leprae.
• Reverse transcriptase-PCR tecnique useful todetect live and dead bacteria
SUMMARY
• Mycobacteiaceae.
• Straight/ slightly curved slender, capsulated,non motile ,non sporing, acid fast.
• Binary fission.
• Cultured- footpad – nine banded armadillos.
• Glia.
• Infect peripheral nerves.
• Capsule- electron transparent
2 capsular lipids- (PDIM & PGL -1)
• Cell wall- 2 layers.
• Cell membrane-responsible for molecules intoand out membrane.
• Cytoplasm- Contains DNA, RNA, storagegranules.
THANK YOU