Tuberculosis Flashcards

1
Q

Where are the bulk of uk TB cases and why?

A

39% are in london because it has a high immigration from high incidence countries.

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2
Q

What causes TB?

A

Mycobacterium Tuberculosis
Mycobacterium Bovine
Among others.

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3
Q

TB causing organisms are AAFBs, what does this mean?

A

Acid-Alcohol fast bacilli.
It means they dont decolourize in acid or alcohol during staining techniques, they are also often resistant to absorping the dye.
We use a ZN stain for them.

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4
Q

Why cant our body overcome TB?

A

The mycobacteria are resistant to macrophages and neutrophils.

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5
Q

How is TB spread?

A

Droplets of M. Tuberculosis form when someome sneezes/coughs and hang around in the air for a long time.
M. Bovis is spread by infected cow’s milk and deposited into the cervical & intestinal lymph nodes.

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6
Q

How does TB occur?

A

The invading mycobacterium trigger Th1 cells which activate macrophages.
Macrophages, epithelioid cells and langhan’s giant cells accumulate around the infection and form granulomas.
Then central caseous necrosis begins.

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7
Q

How does a primary TB infection affect the body?

A

Often asymptomatic but can have fever, malaise, erythema nodosum and chest signs.
Spread from alveoli -> Hilar lymph nodes -> blood to all organs.

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8
Q

How does a primary TB infection resolve?

A

85% reach a primary complex then heal (initial lesion and lymph node).
Can be progressive, latent or cleared.

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9
Q

What can happen if primary TB progresses?

A

Primary focus can enlarge and cavitate while hilar lymph nodes compress the bronchi and eventually cause lobar collapse and discharge into the bronchus leading to T. Bronchopneumonia.

Or 6-12 months later:

  • Miliary TB, a fine mottling of small granulomata all over a CXR
  • Meningeal TB, high protein CSF & high lymphocyte count
  • T. Pleural Effusion
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10
Q

What does post-primary TB refer to?

A

Reactivation of latent infection or reinfection after original disease. Can affect just about any tissue

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11
Q

What are the symptoms of post primary pulmonary TB?

A
Cough with sputum and haemoptysis
Pleuritic chest pain
SOB
Malaise & Weight Loss
Fever & Night Sweats

Maybe crackles/bronchial breathing

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12
Q

What are the risk factors for post primary pulmonary TB?

A

History of diabetes, immunosuppression or TB.
Immunosuppresive Drugs
History of alcohol, IV drug abuse, poor living standards.
Immigration from a high risk area.

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13
Q

How do we investigate a case of TB?

A

Look for 3 positive sputum specimens on successive days.
CXr for patchy shadowing in upper zones and cavitation. Calcification if chronic or healed TB.
CT, bronchoscopy and pleural aspiration/biopsy.

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14
Q

What must we do on finding a TB case?

A

Notify and refer to TB specialists.

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15
Q

Why do we HIV test TB sufferers form areas of high HIV incidence?

A

Because the immunocompromised often get TB so there’s a high chance they’re susceptible because of underlying HIV.

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16
Q

Why do we use multi-drug therapy for TB?

A

It very quickly grows drug resistant to single agent treatment

17
Q

What drugs do we use to treat TB?

A

0-2 months - Rifampicin, Isoniazid, Pyrazinamide & Ethambutol
2-6 months - Rifampicin & Isoniazid

18
Q

What are the side effects of TB treatment?

A

Ethambutol - Optic Neuropathy
Pyrazinamide - Gout
Isoniazid - Hepatitis & Peripheral Neuropathy
Rifampicin - ‘irn bru’ tears sweat & urine. Hepatitis, induces liver enzyme making the oral contraceptive pill useless.

19
Q

Why do we contact trace TB?

A

To determine the source and prevent/treat further spreading.

20
Q

How do we test relatives/friends who are <16 with no BCG?

A
  • A tuberculin test (mantoux or heaf)
  • If positive (indicates exposure & at risk) do a CXR
  • Abnormal then treat as full TB. OR Normal pre-empt with chemoprophylaxis to kill the mycobacteria.
21
Q

How do we test friend/relative whos over 16 so has had a BCG?

A

no tuberculin test as a BCG will show up on it as exposure.

Instead jump straight to a CXR and if normal send them home.