TB - Block 3 Flashcards
How is TB transmitted?
Aerosilized particles from infected person when they cough, speak, or sing
* Particles remain in air for hours
Ingestion of unpasteurized milk
What ways does TB NOT spread?
- Shaking someone’s hand
- Sharing food or drink
- Touching clothing and toilet seats
- Sharing toothbrushes
- Kissing
What are the risk facotrs for infection?
- Large urban areas
- Foreign birth
- Close contact with thos infected
- Non-white
- Male
- Low SE status
- Coinfection with HIV
What are the RF for development of the disease?
- Weakened immune system
- Recent TB infection
- Drug abuse, alcohol, smoking
- Low body weight
- Children <5YO who test positive
- Elderly
What is the cause of primary infection?
M. tuberculosis
What is latent TB infection?
Unhibited growth of TB due to immune system suppression -> without tx it may develop to disease
What is active TB infection?
Reactivation or reinfection can lead to infectiousness and symptomatic
What is miliary TB? Who are more likely to be infected?
Common severe, disseminated form of extrapulmonary TB -> occurs when bacteria spreads in blood stream affecting multiple organs
* Children <4YO
* Immunocompromised
* Elderly
Clincial presentations of TB?
- Coughing blood or mucus
- Chest pain
- Loss of appetite
- Chills
- Night sweats
- Fever
- Weight loss
- Fatigue
- Cough more than 2 weeks
Vaccine used for TB? CI?
BCG vaccine
CI: pregnant women and immunocompromised
What are the diagnostic tests for LTBI?
- Tuberculin skin test
- Interferon-y release assay (IGRA)
What is the purpose for TST?
Mantoux technique: intradermal injection of tuberculin units of purified protein derivative (PPD)
* Delayed types hypersensitivity with 48-72 hrs
What is IGRA?
Measure the release of INF-y in blood in response to TB antigens
* Results available within 24 hrs
When would IGRA be recommended over TST?
>5YO:
1. Likely infected
2. Low-intermediate risk
3. Testing for latent
4. Hx of BCG vaccine
5. Unlikely to return to have their PPD read
RF if TST is positive and ≥5mm?
- HIV
- Recent TB contact
- Nodular or fibroticchanges on chest X-ray
- Organ transplant
RF if TST is positive and ≥10mm?
- Immigrant
- IVDU
- High risk settings
- Mycobacterial lab personnel
- High-risk comorbidities
- Children <4, any child exposed to high-risk adults
RF if TST is positive and ≥15mm?
No known RF
Diagnostic tests for TB?
- Chest X ray: patchy, nodular infiltrates, cavitation
- Sputum exam, culture, testing through acid fast bacilli (AFB) smear
Methods of AFB smear sample collection?
- Sputum volume of at least 3 mL, but the optimal volume is 5–10 mL
- Aerosolized hypertonic saline to induce sputum production
- Flexible bronchoscopic sampling
- Daily sputum collection over three consecutive days is recommended
For suspected extrapulmonary TB, where are samples collected from?
Draining fluid, biopsies of site, blood