Describe the pathogenesis of tuberculosis, paying special attention to the characteristics of Mycobacterium tuberculosis that make it so pathogenic

Question

What will be an ideal response?

Answer 1

Mycobacterium tuberculosis is an extremely effective pathogen. It has a very low infectious dose (about 10 cells). Once inside the body, it is hard to clear because of its slow growth, high levels of waxy, protective lipids such as mycolic acid in its cell wall, and its ability to survive inside phagocytic cells. Another cell wall component, cord factor, is toxic to the body's cells, and inhibits the activity of neutrophils. The immune system does its best to isolate the infection, producing tubercles, which contain M. tuberculosis cells that have been walled off from the rest of the body by inflammatory cells and processes. At best, this process results in a stalemate between the pathogen and the body, and no further disease may ever occur. However, in immunocompromised individuals, the immune system is often not able to keep the pathogen in check; M. tuberculosis therefore breaks the stalemate and begins to spread throughout the lungs, causing secondary or reactivated tuberculosis, with its attendant symptoms of weight loss, chest pain, and breathing difficulty with bloody sputum. From the lungs, the reactivated mycobacterial infection may even spread to the bloodstream and all over the body in the phenomenon of disseminated tuberculosis.
Bloom's Taxonomy: Comprehension
Section: Bacterial Diseases of the Lower Respiratory System
Learning Outcome: 22.16, 22.17