Approaches to Detecting TB

Question 1

when should you not give BCG?

Answer 1

contraindicated if family history of immunodeficiency or suspected of having immunodeficiency

Question 2

age group that is at high risk for early primary TB?

Answer 2

under 5 years

Question 3

most at risk for early primary TB at what timeframe?

Answer 3

in the 12 mos after initial infection

Question 4

how can early primary TB manifset?

Answer 4

• pulmonary disease
• extra pulm disease (eg meningitis, lymphadenitis)
• disseminated disease

Question 5

4 features of pt with latent TB?

Answer 5

• No sx
• Normal P/E
• normal CXR (though may have granuloma)
• TST/IGRA usually positive

Question 6

what % of latent TB pts will develop reactivation disease= post primary disease?

Answer 6

5-10%

Question 7

first investigations for early primary disease?

Answer 7

lateral + PA x-ray

Chest CT

Question 8

pulmonary disease shows what on xray?

Answer 8

ground glass appearnce

hilar/medisatinal/subcarinal LAD

Question 9

3 risk factors for reactivation of TB

Answer 9

• immunosuppression (HIV, DM)
• malnutrition
• meds (steroids, biologics)

Question 10

3 ways reactivation can present

Answer 10

• cavitary disease in apical/upper lung zone
• pleural effusion
• lymphadentiis
• CNS TB lesions
• hepatic or splenic abscess
• osteoarticular infections
• disseminated disease

Question 11

3 ways to get cultures for TB

Answer 11

• induced sputum with hypertonic saline
• fasting gastric aspirates on 3 consecutive mornings
• bronchoscopy

Question 12

test for TB samples?

Answer 12

acid fast bacilli stains
cuture
NAAT

Question 13

does a negative cx/smear rule out TB?

Answer 13

no?

Question 14

tset all TB pts for what?

Answer 14

HIV

Question 15

pts with what TB findings are most infectious?

Answer 15

• cavitary lesions

- sputum positive smears

Question 16

what can give you false positive TST/IGRA?

Answer 16

BCG; Non-tuberculous mycobacteria

Question 17

TST cut-offs?

Answer 17

• at least 5 if immunocompromised or contact

- at least 10 for everyone else

Question 18

do what if someone who had BCG has TST>10?

Answer 18

don’t attribute it to BCG

Question 19

who can have false neg BCG?

Answer 19

infants and kids

Question 20

what is quantiferon/igra?

Answer 20

In vitro blood test that evaluate immune response

Measure release of interferon gamma by T cells in response to Mtb antigens

Question 21

does quantiferon/IGRA cross react with BCG, NTM?

Answer 21

BCG: no
NTM: minimal

Question 22

when can you get false neg quantiferon/IGRA?

Answer 22

immunosuppresion

Question 23

when can you get a false posiitve IGRA?

Answer 23

recent TST

Question 24

latent tb tx?

Answer 24

rifampin, isoniazid OR rifampentin/isonizaid

Question 25

tx for tb?

Answer 25

4 drugs x 2 mos: OR, 2 drugs x 4 mos: INH + rifampin AND consult ID/resp

Question 26

public health stragies

Answer 26

- timely tx of latent cases, contcts - report all TB disease to public health within 48 hours - if resp secretions semar POSITIVE in TB case: isolate in hospital or at home until 3 neg sputums - if initial smear neg, isolate until 2 full weeks of directly observed therapy

Question 27

3 things to do if kid = TB contact

Answer 27

- history/phys - CXR - TST - obtain cases's drug sensitivities

Question 28

Do what for kid <5 yrs who was contact of TB case and TST<5mm?

Answer 28

1 drug ppx (based on senstiviites); repeat TST at 8-10 weeks after last contact with index case; if still <5 mm, stop ppx

Question 29

for kid 5+ years old who was contact and TST <5: do what?

Answer 29

Repeat TST 8-10 weeks later; no ppx

Question 30

for kid at least 5 years old who was contact with an initial of "break of contact" (8-10 weeks after last contact) TST at least 5 mm (no sx, normal exam and CXR)?

Answer 30

treat for latent infection