Tuberculosis

Question 1

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

Answer 1

TB

Question 2

What factors increase the likelihood of TB contraction?

Answer 2

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

Question 3

List some high incidence areas of TB

Answer 3

South east asia
Africa
Russia
South America

Question 4

List some high incidence areas of TB in the UK

Answer 4

London
Glasgow
Birmingham

Question 5

What organism is responsible for TB?

Answer 5

Mycobacterium tuberculosis 
Mycobacterium bovine (in cows)

Question 6

Describe some Mycobacteria spp that cause diseases other than TB

Answer 6

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

Question 7

Describe the organisms responsible for TB

Answer 7

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

Question 8

What stain is used to identify TB?

Answer 8

Ziehl Neilson strain for AAFB organisms

Aniline based red dyes stick to cell wall

Question 9

How is TB transmitted?

Answer 9

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

Question 10

Describe the immunopathology of TB

Answer 10

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

Question 11

What T cell is responsible for TB destruction?

Answer 11

Th1

Question 12

Why is the Th1 response a double edged sword?

Answer 12

Reduces number of mycobacterium

Causes tissue destruction

Question 13

Describe primary infections of TB

Answer 13

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

Question 14

Describe the basis of tuberculin tests

Answer 14

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

Question 15

What is the name of tuberculin tests?

Answer 15

Mantoux/Heaf

Question 16

Describe the effects of disease progression following primary infection

Answer 16

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

Question 17

What causes secondary disease?

Answer 17

Re-activation of latent disease

Re-infection

Question 18

What systems does TB affect?

Answer 18

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

Question 19

List some respiratory symptoms of TB

Answer 19

Cough
Sputum
Haemoptysis
Pleuritic pain
SOB

Question 20

List some systemic symptoms of TB

Answer 20

Malaise
Fever
Weight kiss
Night sweats!!!

Question 21

List some important PMH relevant to TB

Answer 21

DM
Immunosuppressive disease
previous TB

Question 22

List some drugs related to TB

Answer 22

Immunosuppressive drugs

Question 23

List some aspects pf personal social history relevant for TB

Answer 23

Alcoholism
IVDA
Poor social circumstances
Living in poor overcrowded area

Question 24

List some signs only seen in advanced disease

Answer 24

Crepitations - crackles
Bronchial breathing
Clubbing

Question 25

List some conditions that would suggest high index of suspicion for TB

Answer 25

``` Immunosuppressed eg. HIV, corticosteroids Malnutrition Alcoholism Vagrants Previous gastric surgery Malignancy DM Adolescence/elderly Recent immigrants from high risk areas ```

Question 26

What investigations are used for TB?

Answer 26

``` 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 ```

Question 27

List the possible surgical options for TB

Answer 27

``` Phrenic crush Artificial pneumothorax Pneumoperitoneum Thoracoplasty Lung resection ```

Question 28

What is the current drug therapy for TB?

Answer 28

``` For 2 months: - Rifampicin - Isoniazid - Ethambutol - Pyrazinamide For next 4 months: - Rifampicin - Isoniazid ```

Question 29

When are TB patients determined to be non-infectious?

Answer 29

2 weeks later

Question 30

What are some side effects of rifampicin?

Answer 30

``` Orange bodily secretions Induces liver enzymes: - prednisone - anticonvulsants - oral contraceptive Hepatitis ```

Question 31

What are some side effects of isoniazid?

Answer 31

Hepatitis | Peripheral neurpathy

Question 32

What are some side effects of Ethambutol?

Answer 32

Optic neuropathy

Question 33

What are some side effects of pyrazinamide?

Answer 33

Gout

Question 34

When screening for TB in person <16yo with no BCG, how do you proceed?

Answer 34

Tuberculin test | If positive

Question 35

What in addition to chemotherapy should be carried out after diagnosing TB?

Answer 35

Screening | HIV test if from HIV prevalent country