Mycobacterium Leparae Question And Answers

Mycobacterium Leparae Long Essays

Question 1. Classify leprosy. Describe morphology, pathogenesis, and laboratory diagnosis of Mycobacterium leprae.

Leprosy Classification

Based on the immune status of the host, leprosy is classified into four types

  • Lepramatous leprosy
  • Tuberculoid leprosy
  • Dimorphous leprosy
  • Intermediate leprosy

Mycobacterium Leprae Morphology

  • It is weakly gram-positive and strongly acid-fast bacilli
  • Shape: slender, slightly curved or straight bacilli
  • Size: 1-8 μm * 0.2 * 0.5 pm
  • Arrangement: seen singly and in groups
  • In tissues arranged in clumps resembling cigarette ends
  • Position: intracellularly or lying free outside the cells
  • Inside the cells they are present as bundles of organ¬isms bound together by glia
  • These are known as globe
  • Parallel rows of it appear as cigar bundle

Mycobacterium Leprae Pathogenesis

  • Leprosy is a granulomatous disease of humans
  • It has long incubation period
  • Route of infection: nasal discharge and skin
    • Lepromatous leprosy: features
      • Nodular skin lesions
      • Slow and symmetric thickening of peripheral nerves
      • Anesthesia
      • Loss of sensation
      • Ulceration of nodular lesions
      • Nodules become secondarily infected
    • This leads to distortion and mutilation of extremities
    • Tuberculoid leprosy
      • Few skin lesions occur
      • It consists of elevated hypo or hyper-pigmented macular patches
      • Involvement of peripheral nerves occurs
      • Leads to deformities of hands and feet

Read And Learn More: Microbiology Question and Answers

    • Oral manifestations
      • Oral lesions involve the tongue, lip or hard palate
      • Lesions consist of small tumours called lepromas
      • These tend to ulcerate
      • In the facial region, the following changes occur
      • Atrophy of the anterior nasal spine
      • Saddle nose
      • Premaxillary bone recession

Mycobacterium Leprae Laboratory Diagnosis

  • It includes:
    • Acid-fast staining:
      • Acid-fast staining of smears shows acid-fast bacilli arranged in parallel bundles within macrophages [Lepra-cells) confirm the diagnosis of lepromatous leprosy.
      • The viable bacilli stain uniformly and the dead bacilli are fragmented, irregular or granular.
    • Skin and nerve biopsy:
      • These are required for histological confirmation of tuberculoid leprosy when acid-fast bacilli cannot be demonstrated in direct smear.
      • Skin biopsy is also useful in the diagnosis and accurate classification of leprosy lesions.
    • Animal inoculation:
      • Injection of ground tissue from lepromatous nodules or nasal scrapings from leprosy patients into the foot pad of a mouse produces typical granuloma at the site of inoculation within 6 months.
    • Lepromin test:
      • It is not diagnostic test but is used to assess the resistance of patients of M. leprae infection.
      • It also assesses the prognosis and response to treatment.
    • Serological test:
      • Serodiagnosis of leprosy may be carried out by the detection of anti-phenolic glycolipid -1 antibodies.

The test used are:

  • Latest agglutination
  • Mycobacterium leprae particles agglutination (MLPA)

Mycobacterium Leparae Short Essays

Question 1. Lepromin test

  • It is a delayed type of hypersensitivity reaction
  • It was first described by Mitsuda in 1919

Lepromin Antigen:

  • Lepromin antigens used are
  • Integral lepromin
  • Bacillary lepromin

Lepromin Procedure:

  • 0.1 ml of lepromin is injected intradermally
  • Reaction is observed

Lepromin Reactions:

  • The early reaction of Fernandez
    • Consists of erythema and induration in 24-48 hours
    • It remains for 3-5 days
  • The late reaction of Mitsuda
    • Appears after 1-2 weeks of injection
    • It occurs in the form of nodules that may ulcerate
    • It heals in a few weeks

Lepromin Uses:

  • Classification of leprosy
  • Assessment of prognosis
  • Assessment of resistance

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