Tuberculosis Flashcards

1
Q

What is the 2nd leading cause of death from an infectious disease worldwide?

A

TB

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2
Q

What factors increase the likelihood of TB contraction?

A

Poor access to BCG and TB drugs
Overcrowding e.g. cities, prisons
Poor nutrition
Areas of high moving populations

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3
Q

List some high incidence areas of TB

A

South east asia
Africa
Russia
South America

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4
Q

List some high incidence areas of TB in the UK

A

London
Glasgow
Birmingham

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5
Q

What organism is responsible for TB?

A
Mycobacterium tuberculosis 
Mycobacterium bovine (in cows)
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6
Q

Describe some Mycobacteria spp that cause diseases other than TB

A

M. avium intracellulare
M. kansasii, M. malmoense, M. xenopii
M.leprae

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7
Q

Describe the organisms responsible for TB

A

Mycobacterium, acid and alcohol fast bacilli

Non motile slow growing aerobic bacilli
Unusual  very thick cell wall made up of:
 - lipids
 - peptidoglycans
 - arabinomannans

Resistant to acid, alkali and detergents
Resistant to neutrophils and macrophages

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8
Q

What stain is used to identify TB?

A

Ziehl Neilson strain for AAFB organisms

Aniline based red dyes stick to cell wall

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9
Q

How is TB transmitted?

A

M. tuberculosis is airborne, and able to survive for very long periods though is eliminated by UV radiation and dilution

M.bovine is ingested from infected cows milk and deposited in cervical and intestinal lymph nodes

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10
Q

Describe the immunopathology of TB

A
APC recognises TB, presents in LNs
Cells migrate to site of infection
Macrophages/epitheloid cells fuse to form Langhans giant cells
These compartmentalise infections
Central caveating necrosis
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11
Q

What T cell is responsible for TB destruction?

A

Th1

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12
Q

Why is the Th1 response a double edged sword?

A

Reduces number of mycobacterium

Causes tissue destruction

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13
Q

Describe primary infections of TB

A
Usually children
Travels in lymphatics to all over body
Settles in hilar lymph nodes
Erythema nodosum
Primary complex - lesion + enlarged LN
Ghon focus - calcified scar of lesion
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14
Q

Describe the basis of tuberculin tests

A

Intradermal administration of tuberculoprotein (PPD) resulting in inflammation and induration after 48hrs if patient has had previous exposure to TB

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15
Q

What is the name of tuberculin tests?

A

Mantoux/Heaf

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16
Q

Describe the effects of disease progression following primary infection

A
Primary focus enlarges to form cavities
Enlarged hilar LNs compress bronchi 
Discharge secreted into bronchi
Lead to persistent productive cough
Tuberculous pneumonia
17
Q

What causes secondary disease?

A

Re-activation of latent disease

Re-infection

18
Q

What systems does TB affect?

A
Pulmonary
Los
Bone and joints 
Genitourinary
Infertility
Pericardium : constrictive pericarditis 
Abdomen: ascites
Adrenal: addisons disease
Skin: lupus vulgaris
19
Q

List some respiratory symptoms of TB

A
Cough
Sputum
Haemoptysis
Pleuritic pain
SOB
20
Q

List some systemic symptoms of TB

A

Malaise
Fever
Weight kiss
Night sweats!!!

21
Q

List some important PMH relevant to TB

A

DM
Immunosuppressive disease
previous TB

22
Q

List some drugs related to TB

A

Immunosuppressive drugs

23
Q

List some aspects pf personal social history relevant for TB

A

Alcoholism
IVDA
Poor social circumstances
Living in poor overcrowded area

24
Q

List some signs only seen in advanced disease

A

Crepitations - crackles
Bronchial breathing
Clubbing

25
List some conditions that would suggest high index of suspicion for TB
``` Immunosuppressed eg. HIV, corticosteroids Malnutrition Alcoholism Vagrants Previous gastric surgery Malignancy DM Adolescence/elderly Recent immigrants from high risk areas ```
26
What investigations are used for TB?
``` 3 sputum collections over 3 days for: - Ziehl Neilson stain - 8 week culture - sputum PCR CXR - bilateral shadows on apices, calcified CT of thorax Bronchoscopy with bronchoalveolar lavage Pleural aspiration and biopsy in effusions ```
27
List the possible surgical options for TB
``` Phrenic crush Artificial pneumothorax Pneumoperitoneum Thoracoplasty Lung resection ```
28
What is the current drug therapy for TB?
``` For 2 months: - Rifampicin - Isoniazid - Ethambutol - Pyrazinamide For next 4 months: - Rifampicin - Isoniazid ```
29
When are TB patients determined to be non-infectious?
2 weeks later
30
What are some side effects of rifampicin?
``` Orange bodily secretions Induces liver enzymes: - prednisone - anticonvulsants - oral contraceptive Hepatitis ```
31
What are some side effects of isoniazid?
Hepatitis | Peripheral neurpathy
32
What are some side effects of Ethambutol?
Optic neuropathy
33
What are some side effects of pyrazinamide?
Gout
34
When screening for TB in person <16yo with no BCG, how do you proceed?
Tuberculin test | If positive
35
What in addition to chemotherapy should be carried out after diagnosing TB?
Screening | HIV test if from HIV prevalent country