TB Flashcards
what is the aetiology of tuberculosis
myobacterium tuberculosis complex
5
m microti
bovis - transmitted by unpasteured milk
tuberculosis - important agent for human- transmitted by droplet nuclei
carnetti
bacterial spread through air , blood , lymphatic , gastrointestinal
diagnosis of tuberculosis
chest x ray - upper lobe classic infiltration and cavity
fibrocavernous
high index suspicion - high risk patient homeless diabetes alcohol chronic renal failure
sputum cytology - collect sputum early in the morning and 3 specimens
ziehl neelson staining - appears red
lowenstein- jensen medium culture 4-8 weeks - green with yellow dots in the middle
bactec machiene - 21days
PCR - detecting specifc segments of dna
how do you know if you have meningitis from tb?
basal meningitis
if person has remission of tb how do you diagnose them ?
x ray - ghon foccus
you do tuberculum mantoux skin test - sensitized cd4 lymphocytes - proliferate and produce cytokines
5 doses of dead tb intradermal
after 3 days see the diameter of the area of reaction
5mm or more - positive in HIV people only
10mm more - positive in drug users , children less than 4
high risk population - homeless , alcohol, diabetes , lab personal
15mm or more - no risk for tb
false positive - bcg vaccine Bacillus Calmette–Guérin
do not have the active disease
false negative - hodgkin disease sarcodosis
immunosuppressed
tuberculosis gold test - quantiferon
gamma interferon in the blood
t spot tb - number of effector t cell that produces the gamma interferon
clinical manifestations of primary tb ?
prodromal period - non specific symptoms - fever , night swats
initally non productive cough
blood streaking sputum
then massive hemoptysis
mild anemia , leukocytosis in blood test
pleural effusion marker in tb ?
adenosine d aminase
extrapulmonary metastasis of tb goes where tb ?
most commonly seen in HIV
peritoneum pleural liver meninges genitourenal tract
what is the treatment of tb ?
distinguishing the 4 pop of tuberculosis
actively multiplying slowly ' ' sporadically multiplying dormant - no effect for ant tb drugs ---------- initial phase -2 months: first line rapidly dividing - isoniaside - 5mg/kg daily hepatotoxicity and peripheral neurotoxicity
rifampcin - rapidly divinding
hepatoxicity
10mg/kg
(rifabutin - substitue - battles all forms of tb)
pirazinamid(dormant) -
20mg/kg
hepatotoxcity, non gouty polyarthralgia
3x combo until culture negative and no radiological findings
ethambutol (treatment against all forms)
20mg/kg
retrobulbaretinitis
high risk patients - resistance , immunosuppression
4x combo - exceeding 20 months
streptomycin reserve for very high risk
second line - fluroquinilones - levofloxasin
moxifloxacin
amikacin
antituberculosis treatment divided into 2 phases ?
intensive phase
continuation phase
initial phase 2 months - RIF , izoniside , pirazinamide -IMPORTANT - not included then cavitation , and positive tb after 2 months
continuation phase 2 months - RIF and INH
suprvised therapy - DOT (direct observation therapy watching the patient taking the drug is the preferred core management
3 sputum specimens take 24 hours apart
relapse -inh , rif pza plus additional three agents
SINGLE NEW DRUG NEVER SHOULD BE ADDED TO FAILING REGIMEN
pathophysiology of tuberculosis ?
diseases that favour the development of active tb - HIV , silicosis , lymphoma
split into primary and secondary infection
primary - previusly unexposed
inhalation of the droplet nuclei from infectious patients - fewer than 10 percent bacilli reach alveoli
alvolar macrophages ingest the bacilli
prodromal phase
cell mediated immunity :
giving rise to two outcomes - bacillary multiplication - killing macrophage and lyses
monocyts ingest the bacilli and becoming antigen representing cells inducing lymphocytes arrive to give Th1 - INF-Y IL-2
and Th2 - IL-4 , IL-5 - IgE production
formation of granulamtous inflammation and
caseous necrosis in the middle - inhibition of bacterial growth within necrotic environment
viable bacilli remain dormant within macrophages for years if needed
cavities formed - liquefied caseous material containing large number of bacilli drain to lymph nodes - to cause caseating necrosis there to - and dissemination
latent tb - scaring and calcification
immunocomprimised - primary progressive tb - millary tb hematogenous spread
secondary tb - fibrotic granulome reactivated
bronchigenous dissemination
granuloma in tb - ghon focus
granuloma affects the lung and the lymph nod - hon complex
calcification and fibrosis of the granuloma - ranke complex
what are the physical findings in tuberculosis ?
PHYSICAL FINDINGS LIMITED USE
rales - esp after coughing found
occasional rhonchi , amphoric breath sounds - within areas which have large cavity
what are the characteristics of a primary tuberculosis ?
occurs in children
peripheral lesion accompanied by hilar or paratracheal lymphadenopathy
lesion heals spontaneouslu - and later evident as small calcified nodule - GHON lesion
progression by - pleural effusion and empyema
cavitation
hilar or mediastinal lymphadenopathy
hematogenous dissemniation
what are the characteristics of secondary tuberculosis ?
called adult type
results from endogenous activation of latent infection or reinfection
localised in the APCIAL and posterior segments of the upper lobes as well as superior segments of the lower lobes - high oxygen conc
can have necrotic satellite lesions - parenchymal involvement varies
tuberculous pneumonia
proceed to chronic porgressive debilitaing course - becoming formic and can calcify
what are the characteristics for hiv associated tuberculosis ?
upper lobe infiltration and cavitation
late stage of HIV - diffuse interstitial , millary infiltrate
less freq positive sputum smears
MOST COMMON EXTRAPULMONARY Tb
what are some differential diagnosis for TB
influenza
pneumonia
bronchail cancer
