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