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Clinical Pathology > Myobacteria > Flashcards

Flashcards in Myobacteria Deck (20):
1

What type of bacteria are mycobacteria?

Gram positive, bacillus

2

Whats different about mycobacteria to normal bacteria

-very waxy cell wall
-Slow growing
-poor update of gram stain 'ghost cell'

3

What is the difference between infection and disease?

Mycobacterium (i.e. TB) = intracellular pathogen (requires ingestion by host immune system)

Infection - host = carrier of disease but without symptoms

Disease - carrier with associated symptoms

4

Is treatment for TB long or short?

Long - 6 moths using combinational therapeutics (prevents resistance)

5

What are the bacterium that cause TB and leprosy (most of the time)?

M tuberculosis/M Bovis - TB

M leprae - leprosy

6

Whats the main mode of transmission?

Respiratory droplets - most pulmonary disease

7

What is mean by primary TB?

Acquisition of disease

Inhaled bacilli phagocytosed my macrophages (unable to kill)

Macrophages carried back to Hilar lymph nodes

Intracellular multiplication

Disseminated via lymph system/bloodstream

8

Where is the most common site for primary TB in the lung?

Periphery of lung mid-zone

9

What is it called when machrohages carry TB to Hilar lymph nodes?

Ghon focus

10

What is the bodies response to primary TB infection?

Granuloma formation
- Cell mediated immune réponse - antibodies not really involved
-Central area of epithelia cell, giant cells - central region of caseous necrosis
- Fibrosis and calcification of lesions
-Bacilli slowly die/remain viable for 20 years

11

What are the symptoms of primary TB?

Usually asymptomatic, flu like, chest X-ray = normal

- Tuberculin skin test - positive (after acquisition)

12

What condition predisposes individuals to reactivation TB?

Immunosuppressed e.g. malnutrition, alcoholics, HIV

Individuals taking anti TNF alpha medication (immunosuppression) - infliximab

13

What are the symptoms of reactivation TB?

Chronic productive cough (2-3 weeks) - haemoptysis

Weight loss
fever
night sweats

14

What are the main characteristics of reactivation TB?

- coalescing TB - central caseous necrosis

- Cavitation - results in greater viral load - risk of transmission

15

Where does reactivation TB usually occur in the lung?

Apices of the lung (highest O2 tension - require O2 to survive)

16

What is miliary TB?

widespread infection (primary or secondary with erosion of necrotic tubercle) - immunocompromised or young/old

17

What characterises TB meningitis

Gradual onset

May lack constitutional 'quartet' e.g. fever, anorexia, weight loss, night sweats

Personality change

18

What stain is used in TB Diagnosis?

Acid fast bacillus

19

What is the standardised therapy for TB?

'Directly observed therapy short' (DOTS) - course

For pulmonary - 4 antibiotics (RIPS):
1st 2 months
RIFAMPICIN
ISONIAZID
PYRAZINAMID
STREPTOMYCIN

4 months
Rifampicin
Isoniazid

20

What is the skin test that detects latent TB?

Mantoux test

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