TB Flashcards

1
Q

TB - transmission

A

Droplet aerosol - inhalation of droplet nuclei [phagocytosis by alveolar macrophage]
-Humans are only reservoir

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2
Q

TB - highest burden countries

A

8 countries have 68% of global cases:
India, Pakistan, DRC, Nigeria, Bangladesh, China, Indonesia, Philippines

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3
Q

TB - determinants of disease

A

Undernourishment [RATIONS study]
HIV
Alcohol use disorder
Smoking
DM

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4
Q

TB - methods of infection control

A

Administrative controls:
-Triage people
-Respiratory separation
-Effective TB treatment
-Respiratory hygiene

Environmental controls:
-Mechanical ventilation 6-12 ACH, negative pressure
-Natural ventilation
-Germicidal UV systems

Respiratory protection:
-Particulate respirators

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5
Q

TB pleuritis - effusion fluid

A

Exudative effusion:
0.5-5 leucocytes/ml
Protein >30g/l
pH 7.3
Slightly lower glucose

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6
Q

Miliary TB - lab findings

A

Cytopenia
LFTs
SIADH [adrenal]
Low albumin
Urinalysis - proteinuria, sterile pyuria [culture negative, leucocyte positive]

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7
Q

TB spondylitis - presentation

A

Thoracolumbar > cervical - often multiple vertebral bodies
Cold abscess [psoas sign] = avoid drainage

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8
Q

TB spondylitis - treatment

A

Medical
Surgery = only if spinal instability

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9
Q

TB meningitis - CSF

A

Mildly elevated cell count
Lymphocytes - 1/3rd predominance of neutrophils
Elevated protein
Low glucose

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10
Q

TB meningitis - drug CSF penetration

A

Higher in isoniazid and pyrazinamide
Lower in rifampicin and ethambutol

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11
Q

Differential diagnosis of subacute meningitis

A

TB meningitis
Cryptococcal meningitis
Endemic mycoses
Listeriosis
Leptospirosis
Mycoplasma
Syphilis
Scrub typhus
Murine typhus
Toxoplasmosis

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12
Q

TB - diagnosis

A

Microscopy - sputum smear:
-Acid fast bacilli
-Needs 1,000-10,000 bacilli/ml sputum

Culture:
-Slow = 4-8 weeks on solid, 3-6 weeks on liquid
-Solid [Lowenstein Jensen] or liquid
-Can detect 10-20 baccili/ml

PCR - Gene Xpert

Antigen detection:
-LAM antigen in urine [better in HIV patients]

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13
Q

TB - diagnosing drug resistance

A

Phenotypic [culture] - drug susceptibility testing [DST]
-Takes 7-21 days
-Need to have cultured

Genotypic [molecular]
-Xpert = rifampicin resistance rpoB gene
-Line probe assay
-Whole genome sequencing on cultured MTB

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14
Q

TB - activity of drugs

A

Early bactericidal phase = isoniazid
Sterilisation phase = rifampicin, pyrazinamide

Role of ethambutol = prevent resistance in unrecognised baseline isoniazid resistance

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15
Q

Rifampicin - SE

A

Discolouration of bodily fluids
Hypersensitivity - rash, fever
Hepatotoxicity

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16
Q

Isoniazid - SE

A

Peripheral neuropathy - prophylactic pyridoxine [vit B6]
hepatotoxicity

17
Q

Pyrazinamide - SE

A

Hepatotoxicity - most hepatotoxic
Arthralgia

18
Q

Ethambutol - SE

A

Hyperuricaemia
Optic neuritis

19
Q

DILI - when to stop drugs

A

> ALT x3 ULN if symptomatic or bili >x2 ULN

> ALT X5 ULN if asymptomatic

20
Q

TB - duration of treatment for pulmonary and extra-pulmonary TB

A

2 month RHZE intensive
4 month rifampicin and isoniazid continuation phase

21
Q

TB - duration of treatment for TB meningitis

A

2 months quadruple therapy
10 months continuation phase

22
Q

TB IRIS - timing of ART

A

CD4<50 = start ART
CD4 >200 = can usually complete TB treatment course prior to ART

23
Q

Drug resistant TB [DR-TB]

A

TB disease caused by a strain of M tuberculosis complex that is resistant to any TB medicines

24
Q

Multidrug resistant TB [MDR-TB]

A

Resistant to rifampicin and isoniazid

25
Q

Pre-extensively resistant TB [pre-XDR]

A

Resistant ot rifampicin and that is also resistant to at least one fluoroquinolone - either levofloxacin or moxifloxacin

26
Q

Extensively resistant TB [XDR]

A

Resistant to rifampicin and at least one fluoroquinolone and to at least one other Group A drug [bedaquiline or linezolid]

27
Q

Treatment of MDR-TB

A

6 month BPaL/M regimen
-Bedaquiline
-Pretomanid
-Linezolid
-Moxifloxacin

For patients >14 years

28
Q

TB and DM associations

A

More severe pTB and implications for treatment failure
NO increased association with extrapulmonary TB
3.6 fold higher TB risk
More latent TB infection
Increased mortality

29
Q

Paediatric TB - epidemiology

A

Incidence 1million [10% of cases]
Mortality >200,000 children - largest burden <5 years

30
Q

Paediatric TB - presentation

A

pTB
Increased extrapulmonary:
-LN disease
-TB meningitis
-Miliary

31
Q

Paediatric TB - difficulty with diagnosis

A

Difficult for sputum sample:
-Sputum induction <7 years
-Gastric washings <6 months

Paucibacillary