Tuberculosis Flashcards Preview

Resp. Illness > Tuberculosis > Flashcards

Flashcards in Tuberculosis Deck (25)
Loading flashcards...
1
Q

What causes Tuberculosis?

A

Certain species of Mycobacterium including:
Mycobacterium Tuberculosis
Mycobacterium Bovine

2
Q

How is it transmitted?

A

M Tuberculosis is transmitted by droplet transmission from infected sneezes/coughs
M Bovine transmitted by infected milk and deposited in the cervical/intestinal lymph nodes

3
Q

What stain is used for a TB smear?

A

A Ziehl Neissen (ZN) stain, because its an Acid-Fast Organism and so impenetrable to acid based stains.

4
Q

How does primary TB progress?

A

Mycobacteria proliferate in alveoli

  • > Th1 cells activate macrophages and leads to accumulation of macrophages, epithelioid cells and langhans giant cells.
  • > Forms a granuloma and central caseating necrosis begins. (Ghan Focus)
  • > Spreads to Hilar Lymph Nodes (Ghan Complex) -> Blood -> All Organs
5
Q

When do most primary TB infections heal?

A

85% stop at the point of Ghan Complex (Granuloma with central caseating necrosis and infected hilar nodes)
May calcify as it heals

6
Q

What are the 3 possible outcomes of a primary TB infection?

A

Progressive Disease
Latent Disease
Cured Disease

7
Q

What are the symptoms of primary TB?

A

Usually Asymptomatic

Maybe: Fever - Malaise - Erythema Nodosum - Chest Signs

8
Q

How long does latent TB take to cause symptoms and what tissues does it affect?

A

Pulmonary & Skeletal takes 1-5 yrs but up to 40.
Genitourinary & Cutaneous takes 10-15 yrs but up to 40

Can affect virtually any tissue though

9
Q

How does progressive pulmonary TB….progress?

A

The primary focus enlarges & cavitates
Hilar Nodes compress bronchi -> Lobar Collapse
Hilar Nodes discharge into bronchi -> Tuberculous Bronchopneumonia

10
Q

What other forms of pulmonary TB can develop & how long do they take?

A

Miliary TB = Widespread small granulomas - appears like fine mottling on CXR

Meningeal TB = High protein & lymphoctyte CSF - v.bad

Tuberculous Pleural Effusion

Takes 6-12 months

11
Q

What do we look for in a TB Past Medical & drug history?

A

Well for starters…TB
Diabetes
Any immunosupressant disease e.g. HIV
Immunosupressant drugs e.g. corticosteroids

12
Q

What do we look fo in a TB social history?

A
Alcohol
IVDA 
Poor social circumstances 
Immigration or travel from high incidence area
Adolescent, child or elderly
13
Q

What are the symptoms/signs of pulmonary TB?

A

Crackles - Bronchial Breathing - Clubbing

Cough - Sputum - Haemoptysis - Pleuritic Pain - Dyspnoea - Malaise - Fever - Weight Loss - Night Sweats

14
Q

What investigations are there for TB?

A
Sputum Specimens
Chest XR
Chest CT
Broncoscopy with Bronchoalveolar lavage
Pleural aspiration & biopsy
HIV test
15
Q

How do we use sputum specimens to diagnose TB?

A

3 positive specimens on successive days

Can be by smear (ZN stain since AAFB), Cultures (8 wks) and PCR.

16
Q

How does pulmonary TB appear on a CXR?

A
  • > Patchy shadowing, usually on upper lobe or apex as aerobic and those areas are better ventilated, often bilateral.
  • > Calcification if chronic or healed
  • > Cavitation if advanced
17
Q

What tests can we do on fluid and biopsy from a tuberculous pleural effusion?

A

Fluid - cytology and smear/culture

Biopsy - Histology & culture

18
Q

How is TB treated?

A

By a specialist you must legally notify, with multi-drug therapy (to prevent drug resistance arising)
2 months of 4 drugs then 4 months of 2 drugs
Rifampicin + Isoniazid (+ Ethambutol + Pyrazinamide)

19
Q

What are the side effects of rifampicin?

A

Orange urine and tears
Hepatitis
Induces some liver enzymes so prednisalone, oral contraceptives and anticonvulsants are ineffective

20
Q

What are the side effects of Isoniazid?

A

Hepatitis

Peripheral Neuropathy

21
Q

What are the side effects of Ethambutol?

A

Optic Neuropathy

22
Q

What are the side effects of Pyrazinamide?

A

Gout

23
Q

At what point in treatment does TB stop being infectious?

A

Two weeks

24
Q

Who do we screen for TB?

A

We screen household and close contacts of a sufferer, if theyre positive we move on to casual contacts.

25
Q

How do we screen for TB?

A

Young people with no BCG:

  • Mantoux or Heaf test using tuberculin to check for immunity.
  • If +ve follow with CXR
  • If abnormal treat as TB, if normal use chemoprophylaxis with rifampicin

People with a BCG:

  • CXR
  • If abnormal treat as TB, If normal send home