Tuberculosis Flashcards
TB Tests:
– __ smear, culture. GeneXpert for organ system involved (___ type)
– ____ or ___ to identify latent tuberculosis infection
• Order the correct tests to diagnose MTB disease (“active”) and the correct
tests for MTB infection (“latent”)
– AFB smear, culture. GeneXpert for organ system involved (active)
– TST or IGRA to identify latent tuberculosis infection
Igra based test helps dx ___ TB
latent
TB: Airborne Infectious Disease caused by ___
tuberculosis. Requires ____ _____ staining.
TB: Airborne Infectious Disease caused by MYCOBACTERIUM tuberculosis. Requires ACID FAST staining.
2 specific acids in the cell wall of mycobacterium
arabinogalatan and mycolic acid. prevents them from catching staining. need acid fast visualizeation.
TB transmission
-through inhalation– AIRBORNE. aeruosol particles generated by coughing, sneezing, talking of person with active pulmonary TB.
rarely ingested in countries where milk is not pasteurized.
T/F TB can last on a surface for a long time
false. no fomite transmission. not like measels.
3 broad transmission factors of TB
- infectiousness of person with TB: bacterial burdan, caivtary disease, type of TB (laryngeal tb is very infectious), amount of coughing.
- duration of exposure (ex/ same household)
- envirnoment in which exposure occured: air circulation, UV light exposure (can kill bacteria), crowsing.
most infectious type of TB disease
laryngeal TB is more infectious than others. also if they ahve cavitary manifestations or an overall high bacterial burden.
myococavitation
outline the flowchart of the pathogenesis of tuberculosis.
a lot of TB just becomes latent/dormant.
TB Immune response:
__ ___ ingest MTB organism but
can’t kill them initially
MTB ___ inside an unprimed alveolar
macrophage (and can destroy it releasing more
MTB)
Eventually __-___ immunity / delayed-
type ____ are stimulated
• Alveolar macrophages signal ____lymphocytes
and become activated
• Activated ____ are able to kill MTB
TB Immune response:
ALVEOLAR MACROPHAGE ingest MTB organism but
can’t kill them initially
MTB MULTIPLIES inside an unprimed alveolar
macrophage (and can destroy it releasing more
MTB)
• Eventually cell-mediated immunity / delayed-
type hypersensitivity are stimulated
• Alveolar macrophages signal CD4 lymphocytes
and become activated
• Activated macrophages are able to kill MTB
how does HIV play a role in tuberculosis immune response
normally, macrophages ingest the TB and signals CD4 cells to become activated and causing further macrophage activation and cytokine response . in HIV, there are low CD4 levels. have increase risk of reduced immune response.
how is cell-mediated immunity demonstrated?
by positive TST/mantoux test or positive IGRA test. NOTE: TST and IGRA do not demonstrate active disease!! just latent.
two dermatological conditions that can indicate TB cell-related immunit
Erythema nodosum
• Phyctenular conjunctivitis
Latent TB:
diagnosed with ___ or ___
- type of symptoms
- rate of infection?
dx with TST or IGRA
- usually asymptomatic, but at risk for progression to active TB if immunocompromised
- non-infectious
active tb:
diagnosed by:
- symptoms:
- infectiousness?
diagnosed by smear and culture or granuloma evidence.
- symptoms for sure; dyspnea, fever, infection-like symptoms
- infectious if PULMONARY INVOLEMENT.
two branches of active tb
- pulmonary (infectious)
- extra-pulmonary
most common antibiotic to treat history
rifampin
t/f TB is the Leading infectious
disease related cause of
death worldwide
true.
what groups in canada have higher rates of TB
aboriginal individuals have had TB rates at a steady state, whereas non-indigenous canadians have lower and lower levels.
- foreign born canadians also higher rates– especially filipino canadians.
epidemiologic risk factors for active tb
- foreign born
- recent travel
- indigenous
- health acre provider
- travel history
- knoen exposure to pulmonary TB patient
- previous TB diagnosis.
symptoms of pulmonary tuberculosis (the infectious type)
cough, hemotysis, fever, dyspnea, weight loss, night sweats, subacute or chronic presentation. need to do CXR
- possible lymph node involvement.
most common peripheral/extrapulmonary TB site besides lung/pulmonary involvement
peripheral lymph nodes
pulmonary TB investiagtions: most important imaging is ___. It determines the __ of the patient.
CXR. can help determine infeciousness.
chest xr findings of pulmonary tb
- typical clouding in a segment of the lobe (usually upper middle)
- cavitation
- volume loss
- unilateral pleural effusino
- mediastinalhilar lymphadenopathy
hilar lymphadenopathy
focal opacity in characteristic LUL.
- gotta still do more tests, can also be cnacer or something.
small nodular opacities in the RLL. also TB
normal CXR! (this patient still tested positive for TB on smear)
At least___ sputum specimens should be collected
and tested with microscopy as well as
mycobacterial culture
3
• Sputum specimens (either spontaneous or
induced) can be collected on the same day, a
minimum of 1 hour apart
3 ways of collecting sputum for TB test
- expectorated samples or with salt water
- bronchoscopy
- gastric aspirate (usually children)
during the smear and culture assessment, to test positive, there is a ___ to ____ bacteira per ml
5000 to 10,000 bacteria/ml for smear
Outline the scheme for “cough, dyspnea and fever”: the first two branches are normal CXR vs abnormal CXR
If you think patient may have pulmonary TB…..
ISOLATE patient (Airborne Isolation)
• Try to make diagnosis (eg. Send sputum
for AFB smear, culture, PCR test)
• Avoid using fluoroquinolones for treatment
while awaiting further information
samples must be in ____ when sending
saline. not formaline
Extra-Pulmonary Investigations
• Get samples!!
– Send fluid and/or tissue (FNA or biopsy) for
AFB smear, culture, +/- GeneXpert
– Must send for culture in SALINE not formalin – Ideally need culture to confirm diagnosis and do drug susceptibility testing
– Send tissue for histopathology – look for
granulomas/granulomatous inflammation
Extrapulmonary TB may be associated
with pulmonary TB so always do CXR, if
abnormal……
Tuberculous Pleurisy
thoracentesis findings
• Thorocentesis: Exudative
• Lymphocyte predominate
effusion
Pericardial TB
- massive enlarged heart or pericardial effusion– pericardial TB
tests to be done on this patient if you suspect tb
this could be lymph node tb– an extrapulmonary manifestation of TB.
- need a FNA: might see granulomas.
- excision biopsy
- chest xray and culture
spinal TB. could have potts diseases- compression of spinal cord due to inflammatory response
Miliary Tuberculosis
Progressive
disseminated
hematogenous TB
in miliary TB (systemic), you can get ___ on the lungs and get. hypotension due to ____ insufficeincy. this is mostly seen in ___ patients or those who are ____.
in miliary TB (systemic), you can get NODULES on the lungs and get. hypotension due to ADRENAL insufficeincy. this is mostly seen in ELEDELY patients or those who are IMMUNOCOMPROMISED.
T/f sputum culture is sufficient to diagnose miliary TB
false. sputum culture in miliary tb is only 10% positive. you need other confirmatory tests: gold standard is transbronchial biopsies, liver biopsy, bone marrow, urine or blood tests.
TB meningitis, what would by the glucose, protein, cell differential seen on CSF samply
low glucose, high protein. lymphocyte predominent. need AFB and culture. Start empiric treatment. this is an emergency
tuberoma
broad management of active TB
– Isolation-Airborne
– Antibiotic treatment
– HIV testing/Diabetes testing
– Follow Up / Medication Side effect monitoring– must be watched taking the meds
empiric treatment for active TB (RIPE)
must take a combo of 4 drugs (antibiotics). do not one to develop resistance. needs to be directly observed.
RIPE = rifamin, isoniazid, pyrazinamide, ethambutol
standard treatment duration of active TB on RIPE meds
6 months. stop ethambutold if fully susceptible. pyrazidamide is only used in first 3 months. 9 months of treatment needed if the patient can’t use the pZA.
all antibiotics can have side effects. rifampin is a big one though. outline side efects
- biggest one is medication interactions– blocks oral contraceptives. can also cause hepatitis, rash, myelosupression.
second line drugs (other than RIPE) to treat MDR or XDR TB.
- fluroquinolones, aminoglycosides, cycloserine, pas, bedaquiline, liinezolid.
XDR has a high mortality because of its ressitance to fluoquinoline
what tests to do on sick contacts when managing the spread of TB
- id those infected or contact with the infection with 2 TSTs!
- can take 8 weeks to develop a cell-mediated immune response that is picked up by tst. usually do a tst twice– once at exposure and then 8-10 weeks later.
T/F for latent tb, you can give monotherapy antibiotics
true. you need to use a 4-drug combo for active tb though
Latent TB: Identify who is appropriate for testing. Who?
HIGH RISK: HIV, abnormal chest xray, renal failure, revent TB infection, silicosis, transplant recipients.
MODERATE RISK: TNFalpha inhibitor use, prednisone use, young age when infected.
Normal TST expansion on arm for those who are immunocompromised, and then for those who are healthy
>5mm expansion for those with HIV, TB contact, presence of fibronordular disease on chest xray, tnf alpha inhibirots, renal disease, transplantation.
>10mm for those at lower risk (diabetes, malnutrition, silicosis, healthy)
cons of TST
TST is not for active TB
IGRA is a blood test that asseses the production of ___ ___ by t lymphocytes after TB exposure. measures ___ tb
production of interferon gamma by t lymphocytes after exposure to M.tuberculosis antigen
Why aren’t TST/QFT used to diagnosis ACTIVE T
note: IGRA only needed to test those at moderate risk for latent TB. You need both TST and IGRA is high risk
treatment of latent tuberculosis
- rifampin daily for 4 months.
- may also use isoniazid and rifampin for shorter duration, or isoniazid alone for 9 months.
• 34 year old female never smoker • Cough x 4 months • PMHx: sickle cell anemia • Immigrated from Nigeria 10 years ago
DDX?
fibronodular disease (at higher risk for TB)
- myocbacterial balls
MDR TB is resistant to ___ and ___.
XDR TB is resistant to ___ , ___ , ___, and ___
MDR: resistant to INH and rifampin
XDR: resistnat to INH and rifamin and fluoroquinolone and aminoglycoside,
