Mycobacterium Leparae Question And Answers

Mycobacterium Leparae Long Essays

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

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:

• ELISA
• Latest agglutination
• Mycobacterium leprae particles agglutination (MLPA)

Mycobacterium Leparae Short Essays

Question 1. Lepromin test
Answer:

• 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