Tuberculosis
Tuberculosis (TB) is a bacterial infection that is caused by the bacteria Mycobacterium tuberculosis
Disease
MTB is transmitted via droplet nuclei when a person coughs or sneezes and is then inhaled by another individual. The MTB travels to the alveoli where it comes into contact with Macrophages that engulfs the MTB Pathogen. MTB evades the immune system by binding to mannose receptors and is phagocytosed where it secretes a protein that modifies the Phagosome to prevent Phagosome - Lysosome fusion thus preventing Antigen presentation. The MTB then multiplies within the Macrophage until it bursts. However, some MTB Antigen s are still presented which activate T-cells which then activate Cytokines including IFN. IFN causes activation of macrophages which can now destroy the MTB. This is a cell-mediated response and helps to control the infection but MTB can still multiply in inactivated macrophages and eventually spreads to the Bronchi where it can spread to the rest of the body - extrapulmonary tuberculosis [1][2][3].
At Risk:
- HIV
- Diabetes
- Immunocompromised
- smokers
Symptoms
Symptoms include:
- cough
- night sweats
- appeptie loss
- fever
- fatigue
- swollen neck
Prevention
- Good personal hygiene
- Cover mouth and nose when coughing/sneezing
- Vaccination: BCG
Treatment:
Two main antibiotics:
- Isoniazid - synthesis of essential mycolic acids by inhibiting NADH-dependent enoyl-ACP reductase (can cause nerve damage (peripheral neuropathy) so patients are given supplements of vitamin B6
- Rifampicin – affects transcription - β-subunit of RNA polymerase, where it binds and inhibits the elongation of messenger RNA. (side effect: reduced effectiveness of combined contraceptive pill)