TB Flashcards
The global pandemic of TB is fueled by?
spread of HIV/AIDS
poverty
lack of health services
emergence of drug-resistent strains
Causative organism of TB?
How is it spread
Mycobacterium tuberculosis
spread through airborne droplets by person w/ active TB
generally prolonged exposure required for transmission
Are patients with LTBI infectious? Do they show symptoms?
NO! Not infectious
don’t show symptoms
How does Latent TB develop?
immune system responds 2-8 weeks after lungs infected with TB
Macrophages “wall off” the bacteria in the lungs where it may remain dormant for years
Active TB primarily has what kind of granulomas?
Primarily necrotizing (caveating) granulomas
What groups are at highest risk for reactivation to active TB? In what time frame?
Immunocompromised young children substance abuse receiving immunosuppressive therapy malnutrition crowded living spaces nationality (highest in Africa, Asia, Latin America)
greatest risk in first 2 years
During initial infection, what percentage of people develop active (progressive primary TB) vs latent TB?
~5% active- progressive primary TB
~95% latent TB
What percentage of people will develop reactivated TB if not given prophylaxis tx?
10%
Strongest known risk factor for progression to active TB?
HIV
If your patient has sudden onset of TB infection what do you need to be concerned about?
HIV
may be first indication!
If you breathe TB bacteria, list the 4 things that might happen
- You don’t become infected
- You develop latent TB (LTBI)
- You develop active TB (PPTB)
- You develop active TB years after initial infection (reactivation TB)
In a patient with latent TB, what will their sx be? What will their skin test show?
No sx!
+ skin test
In a patient with active TB, what will their sx be?
bad cough >3 weeks chest pain fever, chills, night sweats weakness, fatigue anorexia, weight loss
On physical exam, what sign is considered classic of TB?
post-tussive rales (like pneumonia)
On CXR, what would you see in primary active TB
Hilar adenopathy
Pleural effusions
Hilar/middle lobe infiltrates
On CXR, what would you see in reactivation dz?
Apical/upper lobe infiltrates and cavitations
Repetitive question but need to know:
How would you differentiate primary TB vs reactivation TB on CXR?
Primary: infiltates in hilar/middle lobe
Reactivated: infiltates in apical/upper lobe
What is a Ghon /Ranke complex and what does it signify?
calcified primary focus and hilarity lymph node
residual evidence of healed primary TB
What is the gold standard for dx TB?
Sputum culture
-3 consecutive morning sputum specimens
Options of diagnostic testing of TB
- Nucleic acid amplification test (NAT)
- Sputum culture
- Sputum spear for acid-fast bacilli (AFB)
- Biopsy
With the PPD test, what do you measure?
Induration
not erythema!
If your patient has a positive PPD test, what do you do next?
CXR to rule out active TB
What might give a pt a false positive PPD? What do you do next?
BCG (bacillus Calmette-Guerin) vaccine
follow-up with blood test (IGRA)
List the reaction size that is needed to have a positive skin test (all 3 groups/sizes)
- HIV pts, recent contact w/ TB, immunosuppressed= greater than or equal to 5 mm
- People at high risk of TB (medical workers, HIV negative IV drug users, recent immigrants from countries w/ high TB)= greater than or equal to 10 mm
- People w/ no risk factors= greater than or equal to 15 mm
