W21 - Tuberculosis Flashcards
what is tuberculosis
contagious and airborne infectious disease caused by bacteria
is tb curable
yes
is tb preventable
yes
what are the majority of causes
reactivation of latent infection and delayed diagnosis for lack of awareness
What is TB caused by
bacteria belonging to the mycobacterium tuberculosis complex
what are mycobacterium
different from gram +ve and gram -ve bacteria, they are obligate aerobes that synthesise mycolic acids. They are slow growing between 2 - 10 weeks. Life cycle have different microenvironments that can affect drug susceptibility
describe the mycobacterium life cycle
initial infection: a carrier exposes MTB to the air via coughing
host macrophages in the lung phagocytize the pathogen inflammatory response triggered
bacterial burden is contained inside foamy macrophages
macrophages form the encapsulated vascularised granuloma
other immune cells are present
granuloma matures
cells die and caesum develops at the core of the necrotic granuloma
extracellular baccilli enter their dormant state
Grulomas can fuse to the airways of the lungs and burst, releasing the pathogen to spread to new tissue and new hosts
how is tb transmitted
respiratory route
what is the signs and symptoms of tb
cough for > 3 weeks purulent sputum hameoptysis weight loss malaise fever night sweats
What does isoniazid do
inhibition of biosynthesis of mycolic acids, synthesis of cell wall
what does rifampicin do
inhibition of RNA polymerase
what do pyrazinamide do
intracellular acidification
what do pyrazinamide do
plasma membrane disruption
what does ethambutol do
inhibition of arabinoyl transferase involved with syntesis of cell wall
what should the initial phase of TB be treated with (2 months)
isoniazid
rifampicin
pyrazinamide
ethambutol
