TB

Question 1

What causes the induration you see with a positive ppd?

Answer 1

IFN-gamma release. This is also how the IGRA assay works

Question 2

What would you see clinically with active TB?

Answer 2

CXR granulomas

• Upper lobe infiltrate
• sputum studies with acid fast bacilli

Question 3

How do you treat TB?

Answer 3

1. culture and sensitivity testing

2. RIPE x 6 months

Question 4

What qualifies as MDR-TB?

Answer 4

Resistant to isoniazid and rifampin

Question 5

What qualifies as XDR-TB?

Answer 5

Resistant to isoniazid+rifampin+fluoroquinolone+an injectable 2nd line therapy

Question 6

Where else can TB spread besides the lung?

Answer 6

kidney
brain
bone

Question 7

How many people with LTBI develop TB in the first 2 years? at some point in their lives?

Answer 7

5% for both

Question 8

Who is considered at high risk of TB infection?

Answer 8

1. contacts
2. travel to endemic areas
3. low income
4. IV drugs
5. People working in high risk residential settings (prisons, homeless shelters)

Question 9

Who is at high risk of progressing to active TB?

Answer 9

1. HIV
2. Infected in the last 2 years
3. Immunosuppressed
4. IV drug use
5. kids < 4 yo

Question 10

In whom would a 5 mm TB test be considere positive?

Answer 10

If HIV+
Close contacts
CXR+
Organ transplant pt
Other immunosuppressed (people on IL2, chemo)

Question 11

In whom would a 10 mm test be considered positive?

Answer 11

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

Question 12

What could cause a false positive ppd?

Answer 12

1. Infection with a non-TB bacteria
2. BCG
3. Incorrect antigen/interpretation

Question 13

What could cause a false negative ppd?

Answer 13

1. anergy
2. infected within the last 8-10 weeks
3. < 6 mos old
4. Recent viral or small pox vaccination
5. incorrect plant/read

Question 14

Why is 2 step testing a better standard?

Answer 14

because of the “booster” phenomenon

Question 15

What are the benefits of the IFN-gamma assay?

Answer 15

1. No booster phenomenon
2. Not affected by BCG
3. one visit, results in 24 hrs

Question 16

What are the sx of acute pulmonary TB?

Answer 16

1. Cough for 3 + weeks
2. pleuritic pain
3. sputum, hemoptysis
4. fevers/chills/night sweats
5. appetite loss, fatigue, malaise

Question 17

Can CXR confirm TB?

Answer 17

NO. But would raise suspicion if positive. Also, could rule out PULMONARY TB

Question 18

What else do you need to confirm TB?

Answer 18

1. bacterial CULTURE
2. acid fast sputum
3. NAAT (gold std)

–>You always need a culture to confirm results

Question 19

Does a negative smear rule out TB/

Answer 19

no

Question 20

How long does it take for mycobacteria to grow?

Answer 20

3-6 weeks

Question 21

What are the two phases of TB treatment?

Answer 21

Initial phase: 8 weeks (RIPE)

Continuation phase: after first 8 weeks (Isoniazid and rifampin)

Question 22

when would you consider treating close contacts of someone with TB?

Answer 22

1. Children 5 yrs or younger
2. HIV +
3. Immunocompromised
   - ->these people can give LTBI tx even if ppdnegative

Question 23

What would you do with the close contacts of an MDR-TB pt?

Answer 23

Treat/monitor for 2 years. Depends on susceptibility

Question 24

What are the side effects of isoniazid?

Answer 24

1. Isoniazid: CNS damage: tingling, numblbess
2. Rifampin: coagulopathy, CYP450, organge fluid
3. Pyrazinamide: GI problems
4. Ethambutol: eye damage
   - ->Most of these drugs can also cause hepatitis

Question 25

What are the treatment options for LTBI?

Answer 25

1. 9 mos isoniazid
2. 6 mos INH
3. 4 mos rifampin
4. INH+rifampin combined pill weekly for 3 months (12 pills total)

Question 26

Can you use a ppd or IFN-gamma to test for active TB?

Answer 26

NO