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
Advantages and disadvantages of IGRAs
Advantages:
- requires single visit
- results in 24 hrs
- does not boost subsequent tests
- not subject to reader bias
- not affected by BCG vaccine
Disadvantages:
- must be processed within 12 hrs
- limited data regarding use in children, immunocompromised
- errors in blood collection can occur
- expensive
When do you report active TB?
Confirmed AND suspected cases
within 24 hours
identify contacts
What protective measures are taken when a pt is in the hospital w/ active TB?
- Pt is in an isolated, negative pressure room
- pt wears mask, provider wears respirator
How do you treat Active TB?
4 drug regimen: (RIPE) Rifampin (RIF) Isoniazid (INH) Pyrazinamide (PZA) Ethambutol (EMB)
What is done to confirm compliance of medications?
Directly observed therapy (DOT) for all initiation of tx for all pts
When and why is prophylaxis given in Latent TB?
When: only after active TB is ruled out
Why: to prevent active TB
What is given for prophylaxis in latent TB? What must you monitor?
INH (w/ vit. B6) x 9 months
Monitor LFTs
What is a bad complication of TB (hint: learned about it in Path)? Describe it
Miliary TB
- uncontrolled hematogenous spread of TB
- mult-organ involvement
- dx and treat like pulmonary TB
Side effects of TB drugs: RIF INH PZA EMB
RIF: red-orange tears, sweat, urine, stool
INH: hepatic toxicity (monitor LFTs), peripheral neuropathy (give w/ B6)
PZA: hepatic toxicity, hyperuricemia
EMB: optic neuritis
What can be done for TB prevention?
- targeting testing (those at high risk)
- annual skin testing for pts w/ risk factors
- offer prophylaxis tx to pts with LTBI
Differentiate latent vs active TB: Sx feel sick? Can they spread TB? Skin test results CXR/sputum smear
Latent: no sx do not feel sick cannot spread TB \+ skin test Nl CXR
Active: Has sx feels sick can spread TB \+ skin test may have abnormal CXR or + sputum smear
