Mycobacterium leprae

Mycobacterium leprae


MYCOBACTERIUM LEPRAE

  • Mycobacterium leprae, also known as Hansen’s bacillus spirally.
  • Found in warm tropical countries.
  •  Bacterium causes leprosy (Hansen’s disease).
  • Intracellular, pleomorphic, acid-fast, pathogenic bacterium.
  • Obligate intracellular organisms with polar bodies

MORPHOLOGY

  • Straight or slightly curved rod,aerobic bacillus .
  • Surrounded by characteristic waxy coating unique to mycobacterium.
  • Due to which M. leprae stains with a carbol fuchsin.
  • 5 % sulphuric acid used for decoulration.
  • Live bacilli in tissue appear solid and uniformaly stained.
  • Appear as agglomerates,bound together by glia(lipid like substance)
  • Masses known as Globi.
  • Row of bacilli in globi present a cigar bundle appearance.
  • In tissue section clumps of bacilli resemble cigarette ends.
  • Globi appear in Virchow’s Lepra cells or foamy cell(undifferentiated histocytes)
  • Strian variability is demonstrated recently.
  • PGL-1 phenolic glycoprotienact as virulence factor.
  •  Morphological Index:Measure no.of viable M. leprae
  • Dead bacilli:fragented and granular appreance
  • Bacteriological index:No.of bacilli in tissue,both live and dead.
  • Inc. MI and BI suggest drug resistance/relapse.

CULTIVATION

  • Not grow on artificial media.
  • Can be propagated in foot pad of mice
  • Granulomas appear at site of inoculation.
  • Grows best in cooler tissues
  1. Skin 
  2. Peripheral Nerves
  3. Ant. Chamber of eye
  4. URT 
  5. Testis
  6. For experimental work, Lepra bacilli are best cultured in Armadillos
  • Generation time/Doubling Time 12-14 days
  • Average may be 8-14

RESISTANCE

  • Viable  for 9-6 days
  • In moist soil for 46 days
  • 2 hours in direct sunlight
  • Ultraviolent light 30 mins
Exam Question
 

MYCOBACTERIUM LEPRAE

  • Mycobacterium leprae, also known as Hansen’s bacillus spirally.
  •  Bacterium causes leprosy (Hansen’s disease).

MORPHOLOGY

  • Less acidic 5 % sulphuric acid used for decoulration.
  • Globi appear in Virchow’s Lepra cells or foamy cell(undifferentiated histocytes)

CULTIVATION

  • Not possible
  • Can be propagated in foot pad of mice
  • Granulomas appear at site of inoculation
  • For experimental work, Lepra bacilli are best cultured in Armadillos
  • Generation time/Doubling Time 12-14 days
  • Average may be 8-14
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