Weeks 6-7 Flashcards

1
Q

What is the main mode of TB resistance transmission?

A

Primary resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 dimensions of TB disease?

A

Macroscopic pathology
Infectiousness
Symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Is CXR superior to a symptom screen?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What percentage of all prevalent TB is subclinical?

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What percentage of subclinical TB is smear positive?

A

33%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is subclinical TB?

A

Macroscopic pathology without symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is M tuberculosis hominis spread?

A

Inhalation of infected drops
Conjunctiva
Abraded skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How long is M tuberculosis hominis viable?

A

Dry sputum - weeks
Wet sputum - months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is M tuberculosis bovis transmitted?

A

Milk from infected cows (eradicated by pasteurisation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are symptoms of M tuberculosis bovis infection?

A

Intestinal lesions
Tonsillar lesions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 5 factors of TB pathogenesis?

A
  1. Virulence of bacillus
  2. Induced hypersensitivity
  3. Host immunity
  4. Granulomatous reaction patten
  5. Intracellular bacillus survival
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the virulence of the TB bacillus directly related to?

A

Lipid fractions within the cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is responsible for tissue destruction in TB?

A

Hypersensitivity to bacillus
Sensitisation 2-4w post infection
On 1st exposure, non-specific neutrophilic inflammatory response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the inflammatory reaction become post sensitisation?

A

Granulomatous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does a granuloma consist of?

A

Epitheloid histiocytes
Langhan’s multinucleated giant cells
Plump fibroblasts
Lymphocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does TB avoid phagocytosis?

A

Acidification of phagosome via H+-ATPase exclusion
Recruitment of TACO protein prevents delivery to lysosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does the presence of iron modify cytokine activity?

A

Decreased TNF secretion
Decreased IL-1 and IL-6 mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which protein inhibits macrophage apoptosis in TB?

A

Mcl-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the mechanisms of TB to inhibit phagosome-lysosome fusion?

A

Secretion of serine/theanine protein kinase G
Glycoprotein phagosome composition alteration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is primary TB?

A

TB infection in previously unexposed individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In which stage of TB is Ghon focus found?

A

Primary TB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where is Ghon focus found?

A

Area of greatest volume of inspired air
- Lower part of upper lobe
- Upper part of lower lobe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a Ghon complex?

A

Ghon focus + lymph node involvement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When does Ghon focus caseate?

A

End of 2nd week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the outcomes of primary tuberculosis?

A
  1. Fibrosis and calcification
  2. Progressive pulmonary TB
  3. Transbronchial spread
  4. Lymphatic spread
  5. Haemotogenous spread (miliary TB)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What causes post-primary tuberculosis?

A

Reactivation of latent endogenous infection OR exogenous reinfection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the pathogenetic mechanism for post-primary TB?

A

Bronchial obstruction -> lipid pneumonia -> massive necrosis and cystic cavitation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What areas does post-primary TB usually affect?

A

Apical and posterior segments of upper lobe (Simon’s foci)
Superior segment of lower lobe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the features of post-primary TB?

A

Apical or posterior segments of one or both upper lobes
Airway obstruction causing lobular lipid pneumonia
Intrapulmonary spread via bronchi
Thin-walled cystic cavitation
1-3cm areas of caseous consolidation 1-2cm beneath pleura
Abundant AFBs
Aerosol formation
Remain localised or progress slowly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the outcomes of post-primary TB?

A
  1. Fibrocalcific arrested TB
  2. Progressive pulmonary TB
  3. Pleural effusions, empyema, pleurisy
  4. Endobronchial and endotracheal TB
  5. Intestinal TB
  6. Lymphatic and blood spread with resultant miliary TB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Erosion of which vessels causes TB limited to the lung vs disseminated TB?

A

Pulmonary artery -> limited to lung
Pulmonary vein -> systemic dissemination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Name rare sites for TB

A

Heart
Thyroid
Pancreas
Striated muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the difference in tuberculomas in children vs adults?

A

Location
Adults - supratentorial
Children - posterior fossa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Why is TB endometritis difficult to diagnose?

A

Granulomata are shed every menses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Describe the progress of renal tuberculosis

A

Lesions in kidney cortex bilaterally -> progress in 1 kidney and stationary in the other -> invades pyramids and calyx walls -> large cavitating mass with shell of normal kidney remaining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How is the performance of LF-LAM as HIV severity increases?

A

More severe HIV, better performance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Which PLHIV should get an LF-LAM?

A

Anyone seriously ill admitted to hospital
Any symptomatic patient
Any patient with CD4<200

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are the advantages of TB culture?

A

Highly sensitive
Low limit of detection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are the disadvantages of TB culture?

A

TTP
Requires infrastructure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Why must you be careful with a TB NAAT trace result?

A

Detection of MTB DNA at lowest limit of detection - can occur in previously diagnosed/treated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What are the advantages of TB Xpert Ultra?

A

Improved sensitivity
Large PCR reaction volume
Multitarget genetic markers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Which specimens are recommend for Xpert Ultra in children?

A

Stool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are the common resistance genes seen with rifampicin?

A

rpoB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are the common resistance genes seen with INH?

A

katG
inhA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are the common resistance genes seen with bedaquiline?

A

atpE (ATP synthetase)
rv0678 (efflux pump)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Which culture type yields faster DST results?

A

Liquid culture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What does the proportion method mean?

A

If >1% of isolates are resistant, there is acquired resistance

48
Q

Is heteroresistance detected better by Xpert Ultra or LPA?

A

Equal detection

49
Q

What antigens are used in TBSTs and why?

A

Esat6
CFP10
Do not cross react with BCG

50
Q

What are the drug properties of rifampicin?

A

Bactericidal <1 hour
High potency
Most effective sterilising agent

51
Q

What are the target bacilli of rifampicin?

A

All populations including dormant

52
Q

Which drug has an acidic pH?

A

Pyrazinamide
(The rest are alkaline and acidic)

53
Q

Which drug only targets intracellular bacilli?

A

Pyrazinamide

54
Q

What are the drug properties of INH?

A

Bactericidal >24h
High potency

55
Q

What are the target bacilli of INH?

A

Rapid and intermediate growing bacilli

56
Q

What are the drug properties of pyrazinamide?

A

Bactericidal
Low potency (achieves sterilisation within 2-3months)

57
Q

What are the target bacilli of pyrazinamide?

A

Slow growing bacilli

58
Q

What are the drug properties of ethambutol?

A

Bacteriostatic
Low potency
Minimises drug resistance

59
Q

What are the target bacilli of ethambutol?

A

All populations

60
Q

What is the dose for RHZE?

A

150/75/400/275

61
Q

What is the MOA of isoniazid and ethambutol?

A

Inhibition of cell wall synthesis

62
Q

What is the MOA of rifampicin?

A

Inhibits RNA synthesis

63
Q

What is the MOA of pyrazinamide?

A

Disrupts plasma membrane and energy metabolism

64
Q

Are corticosteroids recommended in TBM?

A

Yes, reduces complications

65
Q

How long can the effect of rifampicin last on OCPs post treatment?

A

Up to 2 months

66
Q

How do you manage pre-existing liver disease and TB treatment?

A

Baseline LFTs
Normal = start treatment
Elevated <2xULN = start and monitor
Elevated >2x ULN = liver friendly regimen

67
Q

How do you manage renal dysfunction and TB treatment?

A

Dose adjust ethambutol and pyrazinamide if CrCl <30 or hemodialysis (RHZE 3 days, RH 4 days)

68
Q

When do you repeat sputum testing?

A

End of intensive phase (conversion)
End of treatment (outcome)

69
Q

How do you manage if sputum smear is positive at 7w?

A

Adherence counselling
PCR, culture and DST
Continue with RHZE for 3rd month
Repeat smear at 11w

70
Q

What is the difference between treatment interruption and loss to follow up?

A

Interruption = <2mo (restart where interrupted)
LTFU = >2mo (restart intensive phase)

71
Q

What class of drug is bedaquiline?

A

Diarylquinoline

72
Q

What is the MOA of bedaquiline?

A

Inhibits mycobacterial ATP synthase

73
Q

Can bedaquiline be used in paediatrics?

A

No clinical data but WHO has provided guidelines

74
Q

What drug class if delamanid?

A

Nitro-dihydro-imidazoxazole

75
Q

What is the MOA of delamanid?

A

Inhibits mycolic acid synthesis

76
Q

What WHO category are:
Bedaquiline
Delamanid
Pretomanid

A

Bedaquiline - A
Dalamanid - C
Pretomanid - no category

77
Q

Can delamanid be used in paediatrics?

A

Yes (paediatric doses)

78
Q

What drug class is pretomanid?

A

Nitroimidazole

79
Q

What is the MOA of pretomanid?

A

Inhibits mycolic acid biosynthesis

80
Q

Can pretomanid be used in paediatrics?

A

No established safety in pregnancy/children

81
Q

What is the regimen for DR TB?

A

9 months total
BDQ for 6 months
+ levo, ethambutol, pyrazinamide, ethionamide, INH for 4 months
FOLLOWED BY
levo, ethambutol, pyrazinamide and clofazamine for 5 months

Ethionamide and INH -> clofazamine

82
Q

If patient is suffering from GIT S/E secondary to ethionamide, what can we replace it with?

A

2 months of linezolid 600mg daily

83
Q

What is BPaLL?

A

Bedaquiline
Pretomanid
Linezolid
Levofloxacin

84
Q

What are the side effects of linezolid?

A

Peripheral neuropathy
Myelosuppression

85
Q

If patient is pregnant or <15yo, what do we use for DR TB?

A

BDLL
D = delamanid

86
Q

What is eligibility criteria for BPaLL?

A

Non-pregnant
<15yo
No exposure to BP or linezolid > 1 month

87
Q

How do we manage DR TB if the patient has exposure > 1 month to BP or linezolid?

A

Do resistance testing
If resistance to levo, exclude

88
Q

What must we be cautious with concerning BPaLL and HIV patients?

A

AZT - myelosuppression
EFV - lowers bedaquiline dose

89
Q

When do we repeat smear and culture for DR TB?

A

Initiation
2 weeks
1 month
Monthly until end of treatment

90
Q

When should culture conversion occur by?

A

Month 2
By month 3, take action!

91
Q

What was the Nix study?

A

3 drug regimen BPaL for 26 weeks

92
Q

What was the Zenix trial?

A

Optimising LZD dose

93
Q

What is the issue with patients defaulting on bedaquiline?

A

BQG half life = 5 months
TB monotherapy causes resistance

94
Q

What are the available TPT regimens?

A

3HP
3HR
6H
12H

95
Q

What is 3HP?

A

3 months INH + rifapentin weekly

96
Q

What is 3HR?

A

3 months INH + rifampicin daily

97
Q

What is 6H

A

6 months INH daily

98
Q

What is 12H?

A

12 months INH daily

99
Q

What TPT can we give >15yo with HIV?

A

3HP
12H

100
Q

In which patients on DTG can 3HP be given?

A

VL<50 within last 6 months

101
Q

What TPT can we give <15yo with HIV?

A

6H

102
Q

What TPT can we give pregnant women with HIV?

A

12H

103
Q

What TPT can we give >15yo without HIV?

A

3HP
3RH
6H

104
Q

What TPT can we give <15yo without HIV?

A

3RH

105
Q

What TPT can we give pregnant women without HIV?

A

3RH
6H

106
Q

What impact does TB coinfection have on ART?

A

Timing of initiation
Drug selection
Drug levels
Adherence
Side effects

107
Q

What is the difference between unmasking IRIS and paradoxical IRIS?

A

Unmasking - TB not known
Paradoxical - TB known

108
Q

Name risk factors for paradoxical TB IRIS

A

Advanced immunosuppression (CD4 <100)
High MTB load
Shorter interval
High baseline inflammation

109
Q

What condition significantly increased paradoxical TB IRIS mortality?

A

CNS involvement

110
Q

What is the clinical manifestation of paradoxical TB IRIS?

A
  1. Lymphadenopathy
  2. Constitutional symptoms
  3. Pulmonary
  4. CNS
  5. Abdominal
111
Q

How do we distinguish TB IRIS from DILI?

A

We can’t!
If severe, treat as DILI and restart ART after TB reinitiation

112
Q

What is the management of mild TB IRIS?

A

Continue ART
Symptomatic treatment
Interventions

113
Q

What is the criteria for steroid use in TB IRIS?

A
  1. TB IRIS likely
  2. Differential excluded
  3. Significant symptoms
114
Q

What is optimal ART timing if CD4>50?

A

Within 8 weeks

115
Q

What is optimal ART timing if CD4<50?

A

Within 2 weeks

116
Q

What is optimal ART timing if CNS TB?

A

Within 4-8 weeks

117
Q

What is the most common cause of clinical deterioration on TB treatment?

A

New AIDS-defining illness