TB Flashcards
What causes the induration you see with a positive ppd?
IFN-gamma release. This is also how the IGRA assay works
What would you see clinically with active TB?
CXR granulomas
- Upper lobe infiltrate
- sputum studies with acid fast bacilli
How do you treat TB?
- culture and sensitivity testing
2. RIPE x 6 months
What qualifies as MDR-TB?
Resistant to isoniazid and rifampin
What qualifies as XDR-TB?
Resistant to isoniazid+rifampin+fluoroquinolone+an injectable 2nd line therapy
Where else can TB spread besides the lung?
kidney
brain
bone
How many people with LTBI develop TB in the first 2 years? at some point in their lives?
5% for both
Who is considered at high risk of TB infection?
- contacts
- travel to endemic areas
- low income
- IV drugs
- People working in high risk residential settings (prisons, homeless shelters)
Who is at high risk of progressing to active TB?
- HIV
- Infected in the last 2 years
- Immunosuppressed
- IV drug use
- kids < 4 yo
In whom would a 5 mm TB test be considere positive?
If HIV+ Close contacts CXR+ Organ transplant pt Other immunosuppressed (people on IL2, chemo)
In whom would a 10 mm test be considered positive?
Immigrants (in the last 5 yrs)
- -IV drug users
- -People working in high risk settings (prisons)
- -Scientists experimenting with TB
- -children < 4
- -young adults who have had a known exposure
- -diabetics, cancer pts
What could cause a false positive ppd?
- Infection with a non-TB bacteria
- BCG
- Incorrect antigen/interpretation
What could cause a false negative ppd?
- anergy
- infected within the last 8-10 weeks
- < 6 mos old
- Recent viral or small pox vaccination
- incorrect plant/read
Why is 2 step testing a better standard?
because of the “booster” phenomenon
What are the benefits of the IFN-gamma assay?
- No booster phenomenon
- Not affected by BCG
- one visit, results in 24 hrs
What are the sx of acute pulmonary TB?
- Cough for 3 + weeks
- pleuritic pain
- sputum, hemoptysis
- fevers/chills/night sweats
- appetite loss, fatigue, malaise
Can CXR confirm TB?
NO. But would raise suspicion if positive. Also, could rule out PULMONARY TB
What else do you need to confirm TB?
- bacterial CULTURE
- acid fast sputum
- NAAT (gold std)
–>You always need a culture to confirm results
Does a negative smear rule out TB/
no
How long does it take for mycobacteria to grow?
3-6 weeks
What are the two phases of TB treatment?
Initial phase: 8 weeks (RIPE)
Continuation phase: after first 8 weeks (Isoniazid and rifampin)
when would you consider treating close contacts of someone with TB?
- Children 5 yrs or younger
- HIV +
- Immunocompromised
- ->these people can give LTBI tx even if ppdnegative
What would you do with the close contacts of an MDR-TB pt?
Treat/monitor for 2 years. Depends on susceptibility
What are the side effects of isoniazid?
- Isoniazid: CNS damage: tingling, numblbess
- Rifampin: coagulopathy, CYP450, organge fluid
- Pyrazinamide: GI problems
- Ethambutol: eye damage
- ->Most of these drugs can also cause hepatitis
What are the treatment options for LTBI?
- 9 mos isoniazid
- 6 mos INH
- 4 mos rifampin
- INH+rifampin combined pill weekly for 3 months (12 pills total)
Can you use a ppd or IFN-gamma to test for active TB?
NO
