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Resp > Lecture 10 - Tuberculosis > Flashcards

Lecture 10 - Tuberculosis Flashcards

1
Q

What demographics are at risk of developing TB?

A

Non-UK born (south Asia and sub-Saharan Africa

HIV + other immunocompromising conditions

Homelessness
Drug use
Prisoners
Close contacts of TB
Young people and old

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2
Q

What are the 2 most common species of bacteria causing Tuberculosis in the Mycobacterium family?

A

Mycobacterium tuberculosis

Mycobacteria bovis (TB in cattle and humans)

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3
Q

What type of bacteria are mycobacterium ?

A

Non motile Rod shaped (bacilli)
Obligate aerobe

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4
Q

What structural features of the mycobacterium (bacilli) make it difficult for the body to eliminate?

A

Long-chain fatty acids with glycolipids in the cell wall:
-structural rigidity
-acid alchol fast meaning they don’t stain

Replicate slowing

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5
Q

How is TB transmitted?

A

Respiratory droplets via coughing and sneezing

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6
Q

What is the infectious dose for TB infection?

A

Only 1-10 bacilli needed

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7
Q

How easily can TB infection be acquired?

A

Highly contagious but not easily acquired

Need prolonged exposure and close contact

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8
Q

What settings is TB infections common?

A

Schools
Provisions
Families

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9
Q

What is the pathogenesis of TB?

A

Inhaled bacteria
Bacilli engulfed by alveolar macrophages (TB infection)
Drain to lymph nodes

Can then progress to active Primary disease or bodies T cells surroud and contain the infection causing latent infection

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10
Q

What can then happen once the TB infection has become a latent infection?

A

Body heals and eliminates

Reactivation leading to symptomatic Post Primary TB

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11
Q

What are the risk factors for reactivation of contained TB to Post primary TB?

A

Anything that compromises the immune system:

HIV
Substance abuse
Immunosuppressive therapy
TNFa antagonists
Organ transplant
Silicosis
Haematological malignancy

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12
Q

How does Primary TB infection differ to Latent TB infection?

A

Primary TB:
Active multiplying tubercle bacilli
CXR abnormal
Symptomatic (cough, fever and weight loss)
A case of TB
Sputum smears and cultures maybe positive

Latent TB infection:
Inactive non multiplying tubercle bacilli
CXR normal
Non symptomatic
Sputum smears and cultures negative
NOT a case of TB

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13
Q

Where is the main site of TB infection?

A

Pulmonary TB (lungs)

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14
Q

What sort of patients is extra pulmonary TB often seen in?

A

HIV infected or immunosuppressed patients
Young children

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15
Q

What is Miliary TB?

A

Where the TB disseminates all over the body through the blood

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16
Q

What histological changes occur in TB?

A

Ceseaous necrosis/granulomas

Where T lymphocytes/macrophages surround bacilli

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17
Q

Look at the xray of a patient with TB on slide 19

A
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18
Q

What are some symptoms of pulmonary TB?

A

Cough
Haemoptysis
Fever
Night sweats
Weight loss and anorexia
Tiredness and malaise

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19
Q

What investigations would be done with pulmonary TB?

A

CXR (when the primary TB damages lungs))

Microbiology stamps

Histology of lymph nodes

20
Q

What are some radiological findings with TB infection?

A

Consolidation often at upper apex/lobes
Cavitation in the consolidation
Ill defined and patchy

21
Q

Look at the last slide at the first x-ray what is this showing?

A

Pleural effusion with a TB infection

22
Q

What is the main staining method to diagnose TB?

What is the problems with it?

A

Ziehl-Neislon stain (but its not very sensitive)

Cant differentate between MTB and NTM and live or dead organisms

23
Q

What is the gold standard for TB diagnosis?

A

TB culture

24
Q

How can TB then be identified from a culture?

A

Whole genome sequencing
Drug susceptibility

25
Q

Look at slide 28 to see a granuloma

A
26
Q

What is a Tuberculin sensitivity test (TST)?

A

When the mycobacterium antigen is injected into dermis
If body has encountered TB before the sensitised T cells will interact with the antigens and will produce a Delayed Type Hypersensitivity cell mediated immune repsonse

27
Q

What is the problem with Tuberculin Skin Testing?

A

False positives (BCG, non TB mycobacteria)

False negatives (immunocompromised)

28
Q

What are Interferon Gamma Assays?

A

Where blood is taken and a specific TB antigen is exposed to the blood
If T cells have encountered it before they bind an produce INTERFERON GAMMA and these levels of interferon gamma are measured

29
Q

What are the 4 drug that a patient must take when being treated for TB?

A

RIPE

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol

30
Q

What are the side effects of taking Rifampicin?

A

Orange secretions in the urine

31
Q

What are the side effects of taking isoniazid for TB treatment?

A

Peripheral neuropathy
Hepatotoxicity

32
Q

What are the side effects of taking Pyrazinamide to treat TB?

A

Heptoxicity

33
Q

What is the side effect for taking ethambutol to treat TB?

A

Visual disturbance

34
Q

Which 2 of the 4 drugs used to treat TB are hepatotoxic?

A

Isoniazid
Pyrazinamide

35
Q

What are 2 other methods of treatment for TB except for giving, Rifampicin, isoniazid, pyrazinamide and ethambutol?

A

Vit D
Surgery

36
Q

Why is TB treated with 4 drugs?

A

High mutation rate so worried about antibiotic resistance

37
Q

How long should drugs be taken to treat TB?

A

3 or 4 drug for 2 months
Rifampicin and isoniazid for 4months

If CNS TB 18months

38
Q

What 2 drugs is multi-drug resistant TB resistant to?

A

Rifampicin
Isoniazid

39
Q

How does miliary TB appears a CXR?

A

Seed like appearance

Milia = seed

40
Q

What can extra-pulmoary TB affect?

A

Lymphadenitis
GI
peritoneal
Genitourinary
Bones and joints
TB meningitis

41
Q

What must a doctor do if he diagnoses a patient with TB?

A

Notify the authorities

42
Q

How is TB infection controlled?

A

PPE
Negative pressure isolation
Vaccines

43
Q

What vaccine is given for TB?

A

BCG vaccine

Bacilli Calmette-Guerin which is live attenuated M.bovis strain

44
Q

Who are BCG vaccines given to?

A

Babies in high prevalence communities
HCP
Close contacts of active resp TB

45
Q

Look at the last slide 2nd CXR, what is this?

A

Ghons focus

Where granulomas are trying to surround the TB at the lymph nodes

Resp (23 decks)

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