What is the causative agent of leprosy?

Appeared in: AIIMS Rishikesh NO - 2019

Explanation

Leprosy, also called Hansen's disease, is a chronic infectious disease.
The causative agent is Mycobacterium leprae, a slow-growing, rod-shaped, acid-fast bacterium.
This bacterium has a predilection for cooler parts of the body, such as the skin, peripheral nerves, upper respiratory tract, eyes, and testes.

Option A: This bacterium is the primary cause of tuberculosis (TB), a different infectious disease that mainly affects the lungs.
Option C: This bacterium is part of the Mycobacterium avium complex (MAC), which causes opportunistic infections, especially disseminated disease in immunocompromised patients, but not leprosy.
Option D: This bacterium belongs to a different genus (Clostridium) and is the causative agent of tetanus, a neurological disease characterized by muscle spasms.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causative agent of Leprosy as background academic context rather than a clinical decision trigger.
Early diagnosis and treatment of leprosy with multidrug therapy (MDT) are crucial to prevent permanent nerve damage, disability, and disfigurement.
Nurses play a key role in patient education regarding medication adherence, wound care for anesthetic limbs, and recognizing signs of lepra reactions, which are inflammatory complications requiring urgent medical attention.
What if? If a patient presents with hypopigmented skin patches and loss of sensation, but the slit-skin smear is negative, the diagnosis might be paucibacillary (tuberculoid) leprosy. The nursing approach would still involve initiating MDT but for a shorter duration (e.g., 6 months) compared to multibacillary leprosy (12 months).

How to Approach the Question

First, identify the key terms in the question: 'causative agent' and 'leprosy'. This is a direct factual recall question.
Scan the options provided. All are names of bacteria.
Recall the specific microorganism responsible for leprosy. The name 'leprae' in Mycobacterium leprae is a strong clue directly related to 'leprosy'.
Differentiate this from other options. Mycobacterium tuberculosis is famously known for causing tuberculosis. Clostridium tetani is known for tetanus. This process of elimination confirms the correct choice.
Select the option that correctly links the disease (leprosy) with its specific causative agent.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 pp. 1445-1447, 1421-1423

E6 Microbiology OneStop Sastry p. 108-110

Practise the full AIIMS Rishikesh NO - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.