Tuberculosis Flashcards

1
Q

What causes TB?

A

Mycobacterium Tuberculosis
Mycobacterium Bovine
Among others.

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2
Q

What is mycobacterium tuberculosis

A

Non-motile bacillus
Slow growth
Aerobic- predilection for APICES of lung

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3
Q

TB causing organisms are AAFBs, what does this mean?

A

Acid-Alcohol fast bacilli.
Don’t decolourise in acid or alcohol during staining techniques
Often resistant to absorbing the dye
ZN stain is used

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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

Airborne - pulmonary & laryngeal spreads
M. Bovis spread by infected cow’s milk
Deposited into the cervical & intestinal lymph nodes.

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6
Q

How does TB occur?

A

Invading mycobacterium trigger Th1 cells which activate macrophages.
1. Macrophage activation-> epithelioid cells-> Langhan’s giant cells
2. Indigestible material produces Granuloma
3. Central caseating necrosis

(Caseating Necrosis = causes tissues to become “cheese-like” in appearance)

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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 happens when primary infection progresses to tuberulous bronchpneumonia

A

Primary focus enlarges- cavitation
Enlarged hilar l.n compress bronchi- lobar collapse
Enlarged l.n discharges into bronchus

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10
Q

What is miliary TB

A

Hematgenous spread of bacteria to multiple organs
Fine mottling on X-ray
Widespread granulomatoma
CNS TB in 10-30%

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11
Q

What does post-primary TB refer to?

A

Infection after latent disease
Reinfection after original disease
Can affect almost any tissue

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12
Q

What is miliary TB

A

Hematgenous spread of bacteria to multiple organs
Fine mottling on X-ray
Widespread granulomatoma
CNS TB in 10-30%

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13
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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14
Q

What are the clinical symptoms of TB

A

Cough
Fever
Sweats (at night)
Weight loss

Fever absent in 37%
Sweats asbent in 39%
Weight loss absent in 38%

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15
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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16
Q

What other ways could you investigate TB

A
  • 3 sputum samples, 8-24 hours gap, at least 1 early morning sample
  • Induced sputum
  • Bronchoscopy with BAL
  • EBUS w/ biopsy
  • Lumbar puncture in CNS TB
  • Urine in urogenital TB
  • Aspirate/ biopsy from tissue
17
Q

How would you diagnose active pulmonary TB

A

CXR
Mediastinal lymphadenopathy(mainly unilateral)
Pleural effusion
Miliary

Pneumonic lesion w enlarged hilar nodes

18
Q

How do we investigate a case of post-primary TB?

A

CXR
Apices, soft fluffy/nodular upper zone
Lymphadenopathy
Consider CT if:
- Normal CXR but clinical suspicion
- Miliary TB
- Cavitation
- Lymphadenopathy
- Targets for Broncho alveolar lavage (BAL)

19
Q

What must we do on finding a TB case?

A

Notify and refer to TB specialists.

20
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.

21
Q

Why do we use multi-drug therapy for TB?

A

It very quickly grows drug resistant to single agent treatment

22
Q

What drugs do we use to treat TB?

A

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

23
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.

24
Q

Why do we contact trace TB?

A

To determine the source and prevent/treat further spreading.

25
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.
26
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.