TB Flashcards
What is BCG
Attenuated live vaccine from M. bovis
functional of BCG
decrease disseminated TB but not decrease pulmonary TB in children
effectiveness of BCG
decrease from 75% in old days, less effective when close to equator
cause of TB
M. Tuberculosis
others: bovis, africannum, microti, Canetti
non-tuberculosis mycobacteria
M avium complex
TB transmission
droplet nuclei containing tubercle bacilli
what is Ghon focus
calcified granuloma
what is primary TB
may cause military spread in immunocompromised or extreme age( contained within 3 wk)
what is post-primary TB
reaction with cavitation
site of TB infection
brain, larynx, LN, pleura, bone, lung, kidney, spine
finding on extra pulmonary tb
skipped lesion in potts disease
nodular appearance and military pattern
transmission of TB depends on
- infectiousness of person
- environment of exposure
- length of exposure
- virulence of tubercle bacilli
how to control transmission
isolation
effective treatment ASAP
3 fates after Tb infection
- spontaneous healing
- acute infection
- containment( 90%)
pathology of TB
caseous necrosis and cell mediated immunity with granuloma in cavitation
when will active TB develops?
when immune system unable to keep tubercle bacilli under control
when will active tb develop
soon after infection or many years
usually within 3-5 year
how many LTBI develop TB disease
10%
which type of TB is infectious
pulmonary TB not extrapulmonary TB
Risk factors to active TB
HIV, Steroid, TNF- inhibitor smoking, chemo, silicosis, organ transplantation, DM
How to treat active TB
4 mon(rifampicin, isoniazid, ethambutol, pyrazinamide) for intensive phase, and 4 mo (rifampicin and isoniazid) for maintenance phase
monoresistent TB
Resistant to any one TB treatment
polyresistent TB
at least any 2 TB ( not both isoniazid and rifampicin)
multidrug resistent TB
resistant to both isoniazid and rifampin
extensive drug resistant TB
Resident to isoniazid and rifampin + fluoroquinolone+ injectable 2nd line( amikacin, kanamycin or capreomycin)
what is LTBI
immune system able to control tubercle bacilli in the body
how to detect LTBI
TST and IGRAs
what inject in TST
PPD read after 2-3ds
how to treat LTBI
isoniazid for 9 mo
what test will have false positive result with previous BCG
TST not LGRAs
what test will have false negative result with HIV
TST and lGRAS
how to control HIV false negative IGRAs
use inbuilt mitogen controls if CD<50
TST and IGRAs positive when?
LTBI and active TB
when is chest x ray abnormal on TB
only active TB
sputum smear and culture positive or negative on LTBI
negative ( but positive if active TB)
how to dx TB
- clinical suspicion
- sputum smear with Ziehl-Nellson stain
- sputum culture
- Solid lowerstein-Jensen( LJ) slopes: 4wk
- liquid mycobacteria growth indicator tube( MGIT) 2wk - PCR
What test for TB can test for drug sensitivity?
MGIT and PCR
M.Leprae cause?
leprosy ( loss of sweat, sharp touch) like cool skin area
m. ulcerous causes
ulcer
Non-TB mycoplasma: avium/ intracellular cause
causing cavity in lung and COPD
