Step 1: Disease Overview.
Tuberculosis (TB) is a persistent infectious disease, predominantly affecting the lungs but capable of disseminating to other organs.
The etiologic agent is the slow-growing, acid-fast bacillus, Mycobacterium tuberculosis.
Step 2: Transmission and Pathogenesis.
Transmission occurs primarily via respiratory droplets expelled during coughing, sneezing, or speaking by an infected individual.
Within the host, the bacteria persist within macrophages and elicit granuloma formation.
The disease can present as pulmonary TB or extrapulmonary TB (affecting lymph nodes, bones, kidneys, etc.).
Step 3: Examination of Choices.
- (A) Treponema pallidum: Agent of syphilis, not TB.
- (B) Mycobacterium tuberculosis: The correct causative agent of tuberculosis.
- (C) Legionella pneumophila: Causes Legionnaires' disease, a form of pneumonia.
- (D) Neisseria meningitidis: Causes meningitis, not tuberculosis.
Step 4: Determination.
The pathogen responsible for tuberculosis is Mycobacterium tuberculosis.