Self Study 2 Flashcards
what bact causes TB
myobacterium tuberculosis
where does myobacterium TB thrive
upper lobe and upper part of lower lobe
why does MBTB thrive in certain areas of the lung
they are aerobic bacteria and these areas of the lung have inc o2 content
what makes mbtb resistant to destr
outer waxy capsule
what does the outer waxy capsule on mbtb allow
to continue prod in dead and calcified lesions
what are mbtb capable of
retaining growth
how many new tb cases occur a year
8 mill
how many people die from tb a year
2 mil
how many new cases of tb occured in canada in 2003
1600
how many people in canada died from tb in 2003
750
who has inc incidence for tb
people living in crowded conditions, foreigners
2 forms of tb
m. tuberculosis hominis
m. tuberculosis bovine
another name for m. tuberculosis hominis
human tb
how is bovine tb acquired
drinking milk from infected cows
what part of the body does m. tb bovine affect first
GI tract
how does h. tb hominis travel
airborne infc.
mechanism of tb m hominis travel
droplets are in air when infected person coughs, sneezes, talks, particles evaporate and are suspended in the air
what happens when a tb bacteria is inhaled
travel down bronchial tree and deposit in alveoli
what happens to the bacilli once they are deposited in alveoli
alveolar macrophages phacocytose
why are bacilli not killed after alveolar macrophages attack them
cell wall blocks the fusion of phagosomes and lysosomes
what happens when the fusion of phagosomes and lysosomes is stopped by the bacilli
macrophages initiate cell mediated immune response
how are bacilli antigens presented to t lymphocyte
macrophages which have ingested them present them
why is lung tissue damaged in TB
lytic enzymes are released by t macrophages
why do t macrophages release lytic enzymes
sensitized t lymphocytes stimulate macrophages to produce lytic enzyme
Ghon focus
granulomatus legion
how do ghon focus’ develope
increased cell mediated immune response
what does a ghon focus contain
tubercle bacilli, modified macrophages, other immune cells
what causes tissue necrosis
when the number of organisms is high, H rxn lt necrosis
what lymph nodes do tb bacteria travel down via lympth channels and end up
tracheobronchial lymph nodes
what happens when tb bacteria is in tracheobronchial lymph nodes
cheese like granulations form
ghon complex
combination of primary lung lesions and lymph node granulomas
what happens to a ghon complex over time
heals, but dormant bact may remain
what happens if somebody with dormant TB becomes immunocompromised later on
dormant infc can dev into secondary tb
primary tb
infc that develops in previously unexposed persons
what happens when people with intact immune systems develop a primary infc
supressed infc
why is the infc in primary tb supressed
t lymphocytes and macrophages surround organisms and limit spread
do people with tb have an active disease
no
what happens in primary tb when a pt has compromimsed IR
they dev progressive primary tb with destruction of lung tissue that spreads to multiple sites within the lung
miliary tb
rare form of tb that moves into blood vessel causing lesions
secondary tb
occurs when pt has laready been exposed to disease
what causes secondary tb
reinfection from another inhaled droplet or reactivation of a healed primary lesion
what is an aggravating factor for secondary tb
cell mediated H rxn that causes cavities to merge and create one large cavity
what can merging of cavities cause
plueral effusion
tb emphysema
mnfts primary tb
non spec and insidious fever wt loss fatigue night sweats
what other mnfts may accompany primary tb
pleuritis
lymphadenitis
mnfts of secondary tb
low grade fevers night sweats fatigue anorexia wt loss dry cough
what does disease process of secondary tb do to a dry cough
turns it into a productive cough with purulent or blood tinged sputum
what mnfts occur in later secondary tb
dyspnea
orthopnea
dx for tb
tuberculin skin tests
cxr
culture
what does it mean if a person tests positive for skin tb
they may not have an active form, they have been exposed to baccillus and cell mediated immunity forms
what do cxr’s show in pts with tb
consolodated lesions (active) lesions, scars (inactive)
goal of tx for tb
eradicating bacteria while not creating drug resistance in pt
types of tx for tb
chemo
antimycobacterial tx
what drug is used to treat tb in pts >35yo, immunocompromise, peds,
isoniazid
what drugs are usually used in tb
INH rifampin pyrazinamide ethambutol streptomycin
how do we avoid drug resistance
use combinations of drugs
what vaccine is used in pts who have high risk of dev infc
calmette geurin
what does calmette geurin do in skin tests
changes ability to detect dormant tb,
where does the calmette geurin vaccine inconsistent
pulmonary tb
