Flashcards in tuberculosis Deck (22)
what impact does HIV have on TB?
it promotes it because they dont have CD4+ t-cells and so they fail to tolerate it
what is the shape of mycobacterium tuberculosis?
rod shaped gram positive bacillus
slow growing member of the genus
why is it's size important?
2-5 microns so it can be transferred by droplets eg sneezing or singing
who gets TB?
young people, babies, elderly people
what are the symptoms of TB?
- persistant cough > 3 weeks
- occasional haempotysis
- pleuritic pain
- upper zone crackles
- night sweats fever
- weight loss
how do you diagnose TB?
- history and examination
- simple blood tests = no specific one for TB
- radiology/imaging = swollen lymph glands, cavity in lungs
- microbiology and histology
what is the microbiology and histology of TB?
- specimens = sputum x3, early moring urines x3
- culture = solid phase, liquid phase, drug sensitivities
histology = granulonata with central caseous necrosis
how do we treat active TB?
- 4 drugs for 2 months
= rifampicin, isoniazid, pyrazinamide, ethambutol
2 drugs for a further 4 months = rifampicin, isoniazid
how do we treat latent TB?
2 drugs for3 months
- rifampicin, isoniazid
- or 1 drugs for 6 months = isoniazid
what is the immune response for TB?
- the macrophage is the intial intracellular primary niche of MTB
2. immune recognition
3. slow onset of Th-1 biased adaptive immunity
4. enhanced effector mechanisms
what do you look for in the cell structure for TB?
granulomas - they can keep the disease at bay from weeks to years (latent)
does TB involve caseous necrosis?
yes - cheese like
what happens after exposure to TB?
- 90% remian well
- 10% have lifetime risk of disease
what is the pathology of TB?
- type IV hypersensitivity eg granulomas and necrosis
what is primary TB?
1st exposure and up to 5 years after te disease
- ghon focus in mid zone periphery, large hilar nodes
what is secondary TB?
reinfection of disease in person with some immunity (fibrosis and cavititating apical lesion)
why does TB become reactivated?
- decreased T cell function due to age, HIV, immunosuppressants like steroids or chemo
- reinfection at high dose or more virulent organism
what are the side effects of rifampicin?
what are the side effects of isoniazid?
what are the side effects of pyrazinaide?
what are the side effects of ethambutol?