TB

Question 1

What is latent TB infection (LTBI)?

Answer 1

A state of persistent immune response to stimulation by MTB Ag without clinical manifestations of active TB

Question 2

What is the percentage of LTBI progressing to active infection?

Answer 2

5-10%

Question 3

LTBI Rx

Answer 3

3HR
6H
9H
3R

Question 4

What is the special consideration before starting LTBI Rx?

Answer 4

To exclude active PTB or EPTB prior
- do:
CXR
AFB smear - sputum or BAL
Ix for EPTB (e.g. CTB, Bx)

Question 5

How to test for LTBI?

Answer 5

1) Tuberculin skin test (TST/ Mantoux), or
2) Interferon-gamma release assay (IGRA)
- both have similar sens & spec

Question 6

What is the disadvantages of Mantoux compared to IGRA

Answer 6

however both do not differentiate between active/latent infection

Mantoux causes
False negative in:
CKD
Low protein state
Disease affecting lymphoid organs (e.g. lymphoma, sarcoidosis)
Incorrect measurement

False positive in:
NTM infection
Previous BCG injection
Incorrect measurement

Other disadvantages of Mantoux Test:
Requires 2 visits
Takes 48-72h

Advantages of IGRA:
not affected by BCG
Results available in 24h
Results not affected by bias/ error by the reader

Question 7

How to interpret Mantoux (according to CDC)

Answer 7

Positive in:
≥5mm:
1) HIV
2) on steroid ≥15mg/d for ≥1m
3) on TNFi
4) recent contact with TB case
5) CXR with fibrotic changes suggestive of PTB

≥10mm:
at risk pts but do not belong to the above group inc HCW

≥15mm:
pts not at risk/ from low prevalence countries

Question 8

When is IGRA recommended

Answer 8

1) in CKD/ transplant candidates
2) in pt not expected to come back for Mantoux reading
3) in pts who just had recent BCG
4) in pts who had previous NTM infection
5) close contact whose Mantoux is 5-9mm
6) in pts offered LTBI Rx but not convinced
7) HCW who require annual screening of LTBI (working in high risk areas)

Question 9

What are the LTBI Rx options

Answer 9

3HR
4R
6-9H

Question 10

What is the LTBI Rx follow-up?

Answer 10

total of 2y f/up

Day 1: basic bloods, viral screen, CXR
Week 2-4: LFT
End of LTBI Rx: CXR
3m post: monitor Sx
9m post: monitor Sx
18m post: CXR & monitor Sx

Question 11

How effective is LTBI Rx

Answer 11

33% overall reduction to active TB
64% reduction in Mantoux positive pts
Protective effect >5y

Question 12

TB Rx consideration in pregnancy/lactating women

Answer 12

Pre-pregnancy:
1) Enroll them to pre-pregnancy clinic to be reviewed by FMS & O&G
2) If not planning for pregnancy, advice for use of other forms of contraception apart from OCP/progesterone-only pills while on R until 1m post cessation

During pregnancy:
Meds:
1) Given Pyridoxine 30mg OD
2) Do not give Streptomycin as it may cause fetal ototoxicity

Ix:
CXR should not be delayed - use abdo shield for CXR

Others:
1) Advise for compliance to have best outcome for both mother & baby
2) Delivery in hospital

For the newborn:
1) Refer newborn to peads & start 6m H as prophylaxis (if active TB ruled out)
2) Defer BCG to newborn if mother was diagnosed <2m before deliver or sputum +ve right before delivery.

Breastfeeding:
1) Breastfeeding should be encouraged - H & R concentration too low to affect or treat newborns
2) R can cause orange-coloured breast milk which is harmless
3) Wear surgical mask during breastfeeding

Question 13

TB meds needing adjustment for CKD

Answer 13

eGFR <30ml/min:
E,Z & Levofloxacin - 3x/week

Question 14

When to initiate ART in HIV pt with TB

Answer 14

In CNS TB, delay ART until 8w ragardless of CD4 count
In other types of TB,
delay ART to 2w if CD4<50,
delay 8w if CD4 ≥50

Question 15

What’s the follow-up following ATT?

Answer 15

Baseline: viral screen, basic bloods, AFB smear, sputum MTB C&S, CXR

2w: LFT +/- AFB smear (if returning to work/school)

2m: AFB smear, CXR

5m: AFB smear

6m: AFB smear, CXR

Others: weight, eye Ax, UPT, blood sugar

Question 16

Mx of DILI

Answer 16

Question 17

What to do if smear still positive after 2m of IP? (Delayed conversion)

Answer 17

Question 18

What to do in Rx interruption?

Answer 18

Question 19

What is the suggested Rx regimen if H/R/E/Z is unable to be tolerated?

Answer 19

No R: HZEL 12-18m
No H: RZE 6-9m
No Z: HRE 6-9m
No E: HRZ 6-9m
No H & Z: REL 9-12m

Question 20

When to stop ATT in DILI?

Answer 20

Symptomatic: ALT>120
ASx: ALT >200

Question 21

What are the common post-TB complications?

Answer 21

Lung parenchyma:
Lung fibrosis
Pulmonary aspergillosis
NTM

Airways:
Bronchiectasis
Tracheo-bronchial stenosis

Pleura:
Pleural thickening
Fibrothorax

Question 22

Tracheo-bronchial stenosis - cause & Rx

Answer 22

Causes:
1) Direct inoculation of TB bacilli from lung parenchyma
2) Erosion through infected lymph nodes
3) Peribronchial seeding from haematogenous spread

Rx:
1) Surgical: resection & reconstruction
2) Bronchoscopy:
- balloon dilatation
- mechanical bronchoscopy (using progressively larger diameter rigid bronch)
- laser photo-resection
- mitomycin application

Question 22

Post TB tracheo-bronchial stenosis - cause & Rx

Answer 22

Causes:
1) Direct inoculation of TB bacilli from lung parenchyma
2) Erosion through infected lymph nodes
3) Peribronchial seeding from haematogenous spread

Rx:
1) Surgical: resection & reconstruction
2) Bronchoscopy:
- balloon dilatation
- mechanical bronchoscopy (using progressively larger diameter rigid bronch)
- laser photo-resection
- mitomycin application
- silicon stent insertion

Question 23

Post-TB lung fibrosis - Ix & Mx

Answer 23

Ix:
CXR/HRCT
Spiro & DLCO
6MWT
ABG

Mx:
Chest physio
Nutritional Ax - dietitian input
Psychological support
Vaccination
Smoking cessation
LTOT

Question 24

Post-TB Chronic Pulmonary Aspergillosis (CPA) - Types & Rx

Answer 24

Types:
Chronic cavitary aspergillosis (CCA)
Chronic fibrosing aspergillosis (CFA)
Aspergilloma
Aspergillus nodules

Rx:
1st line: Voriconazole/ Itraconazole
Others: Ampho B, Micafungin, Caspofungin
Surgeical resection
BAE

Question 25

When should sputum LPA be sent?

Answer 25

1) persistent smear +ve despite 2m of IP
2) Prior to MDR Rx regimen to determine Inh-A & katG mutation
3) Smear positive PTB with index case having HrPTB

Question 26

What are the available TBIS?

Answer 26

TBIS:
10A - Awal
10B - Buku
10C - Contact
10D - Defaulter
10E - Electronic
10F - Follow-up
10G - Gagal
10H - Harian
10I - Injection
10J - Jalan
10K - Keluar

Note:
10A to be completed by Dr upon diagnosis

10B = TB wallet

10C = used by inspector kesihatan to ask TB contacts for screening

10D = form to report on defaulter

10E = TB booklet for pt to sign/DOT

10F = Form fr follow up in a different centre

10G = Investigative form to determine factors of default

10H = To monitor TCA, regimen of Rx, date of smear conversion and reason for change of regimen

10I = To record all info re the Rx, smear result, DOT & outcome of Rx

10J = Form to investigate TB death

10K = For monitoring of pt that moved out of the original treatment centre

Question 27

What are the Rx outcomes for TB pts? (Excluding MDR or RR-TB)

Answer 27

1) Cured
= PTB with bacteriologically confirmed TB at the beginning of Rx, who was smear or culture -ve in the last month of Rx AND on at least one previous occasion

2) Rx completed
= Completed Rx
- without evidence of failure
- but no record of sputum smear or culture
- in the last month of Rx AND on at least one previous occasion were negative,
- either because the tests were not done or because results were unavailable

3) Rx failed
= Sputum smear or culture positive at month 5 or later during Rx

4) Died
= TB pt who died of any cause before or during TB Rx

5) Lost to follow-up
= TB pt who did not start or had Rx interruption for ≥2 consequtive months

6) Not evaluated
= TB pt whom no Rx outcome has been assigned. (included case transferred out or outcome not known to the reporting unit)

7) Rx success
= The sum of cured and Rx completed

Question 28

Mx of newly diagnosed TB

Answer 28

1) Hx taking, inc close contact
2) Baseline Ix: FBC, RP, LFT, HIV, sputum MTB C&S, CXR, visual acquity, ishihara test
3) Counselling re active TB, transmission, Rx, duration of Rx, ADR, VOT/DOT
4) Start ATT - 2m EHRZ, 4m HR
5) TCA arrangment
6) O&G involvement - in preg pt
7) Notify infectious disease ANNEX 2 & TBIS 10A-1
8) Close contact screening

Question 29

TB infection control
- causes of inefficient TB control

Answer 29

Causes of inefficient TB control:
a) delayed suspicion or Dx
b) failure to isolate active pulmonary disease
c) failure to recognise on-going infectiousness of pts
d) lab delat in identifying and susceptibility testing of MTB isolates
e) Inadequate respiratory isolation facilities - lack of isolation rooms and recirculation of air from isolation room to the rest of the hospital
f) delayed initiation of ATT

Question 30

Health care worker TB screening

Answer 30

3 types of screening:
1) Preplacement screening
2) Periodic screening
3) Pre-retirement/ change of workplace screening

Question 31

TB infection control
- steps to be taken for better TB control

Answer 31

TB infection control strategies:
1) Risk assessment
2) Risk category: Low/ Medium/ Potential ongoing transmission
3) Risk control:
a) Administrative control:
- Screening & conduct TB risk Ax
- Assign TB control committee/
- Develop and implement TB infection control plan
- Ensure availability of prompt of lab processing & reporting
- implement effective work practices
- ensure proper cleaning & sterilization & disinfection of equipment
- Educate, training & counselling of HCW re infection control
- promptly identify ppl with TB Sx
- separate infectious pts
- control spread of pathogen by giving pt face mask
- minimise time spent in healthcare facilities

b) Engineering control:
- HEPA filter/ UVGI
- Environmetal control: open window, free flow of ambient air, negative pressure room

c) Personal Protective Equipment
- cough etiquette

Question 32

TB Case Detection and Case Screening

Answer 32

Case detection
= TB is diagnosed in a pt and is reported within the national surveillance system and the to WHO

Systematic screening
= systematic identification of ppl with suspected active TB, in predetermined target group, using tests, examinations or other procedures that can be applied rapidly

3 TB risk groups that require systematic screening:
1) Household of active TB case
2) HIV positive
3) Current/ former workers in workplace with silica exposure