TB Flashcards
what is TB bact
mycobacterium
- special cell envelope
- leads to it being acid fast - doesn’t show up on gram stain
- grows slowly - slow cultures
how is TB transmitted
ppl with pulmonary or laryngeal aerosolize
- local defences can destroy if it doesn’t get too deep
what happens if gets into alveoli
- cell mediated immunity creates a granuloma
- person now has latent TB
what is chance of going active
10% will go active
50% of those in 2 year
- most TB in world is reactivated
what is TB in toronto
from immigrants
2 ways to test latent
- skin test - TST
2. interfereon gamma release assay - IGRAS
3 ways to diagnose active
- acid fast bacilli and cultures
- path consisitent with necrotizing granulomas
- clinical presentations
what is TST
- glyscerol extract of TB is put in skin
- read 48-72 hours later
what is IGRA
- tests to see if WBCs from infected patient will release IFN-g when mixed with antigens from TB
how does TST and IGRA compare
- IGRA are more specific than TST if previus BCG given
- neither can separate latent from active
- IGRA more specific for TB versus other non TB bacterium
3 parts of interpreting TST
- size of induration
- PPV
- risk of disease if truly infected
3 levels and situations that would be considered pos.
0-4
- normal, but for children
2 things that PPV is confounded by on TST
- previous BCG - after 1yo
- previous NTM
- found in soil and such stuff
7 things that make a person high risk
- AIDS
- HIV
- tranplant
- silcosis
- chronic renal failure
- carcinoma of head
- recent TB
7 things that make increased risk
- steroid tx
- TNF-a is
- diabetes
- underweight
- young when infected
- smoker
- granuloma
what to do if find pos. TST
rule out active TB
- Hx and Phx
- CXR
- sputum
4 groups to offer Tx to
- ALL CONVERTERS
- new immigreants
- HIV and immunosupressed
- those with increased risk
what is LTB Tx
- INH 9 mo
2. rifampin 4 mo
what are SE of isoniazide
- hepatotoxicity
- rash
- GI upset
- peripheral neuropathy
how to test after pot. TST
will always test pos. again, and can get bigger
Sx of active TB
- cough
- fever, chills, night sweats
- weight loss
- hemoptysis
4 other risk factors
- aborig
- previous TB or contact
- marginalized pop
- immunosupressed
3 steps if active suspected
- isolation precautions
- CXR
- resp secretion analysis
what are extrapulm manifestations
- nodal
- pleural
- CNS
- percardial
- MSK
- peritoneal
- genitourinary
- miliary (disseminated)
what is MGMT of active
always start 4 drugs until cultured
- INH
- rifampin
- pyrazinamide
- ethambutol
why different drugs
hits different types
3 different types
- extracellular with high O2
- areas of low O2: inside cells, areas of fibrosis or caseum
- areas of fibrosis or solid caseum
