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Flashcards in TB Deck (24)
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1

Primary TB

naïve TB infection
- Organism multiplies at pleural surface → Ghon Focus
- Macrophages take TB to LNs - Ghon complex
- Mostly asymptomatic
- Rarely causes primary progressive TB but may occur in immunocompromised

2

Ghon complex

Nodes + lung lesion

3

Ghon Focus

TB Lung lesion

4

Ranke complex)

Fibrosis of Ghon complex → calcified nodule

5

Latent TB

Infected but no clinical or x-ray signs of active TB
- Non-infectious
- May persist for years
- Weakened host resistance → reactivation

6

Secondary TB

Usually reactivation of latent TB due to ↓ host immunity
- Typically develops in the upper lobes
- → cavitation and
formation of caseating granulomas

7

Clinical features of pulmonary TB

Cough, sputum
Malaise
Fever, night sweats, wt. loss
Haemoptysis
Pleurisy
Pleural effusion
Aspergilloma / mycetoma may form in TB cavities

8

Causative organism

Mycobacterium tuberculosis

9

Clinical features of meningeal TB

Headache, drowsiness
Fever
Vomiting
Meningism - photophobia and neck stiffness
Worsening over 1-3wks
Papilloedema

10

GU TB

Frequency, dysuria, loin/back pain, haematuria
Sterile pyuria

11

Bone TB

Vertebral collapse and Pott’s vertebra

12

Ix

Bloods - FBC, U+Es, LFTs, CRP
Sputum culture x 3 and microscopy
Blood culture
CXR

13

Test for TB

Tuberculin Skin Test
IGRA - interferon gaba release assay

14

Signs of TB on CXR

Mainly upper lobes.
Consolidation
Cavitation
Fibrosis
Calcification

15

Stain for mycobacterium tuberculosis

Ziehl-Neelsen stain - show acid fast bacili

16

Tuberculin Skin Test

Intradermal injection of purified protein derivative

False +ve: BCG, other mycobacteria, prev exposure (latency)

Cannot distinguish between active and latent or vaccinated

17

Interferon Gamma Release Assays

Pt. lymphocytes incubated with M. tb specific antigens → IFN-γ production if previous exposure.

Will not be positive if just BCG (uses M. bovis)

Cannot distinguish between active and latent

18

Mx of TB

Mx w/o culture if clinical picture is consistent with TB

- Stress importance of compliance
- Check FBC, liver and renal function and eyes before medication

Mx: RIPE
- 2 months:
Rifampicin + isoniazid + pyrazinamide + Ethambutol

- 4 months:
Rifampicin and isoniazid

Contact tracing

19

Rifampicin s/e

hepatitis, orange urine, enzyme induction

20

Isoniazid s/e

hepatitis
Peripheral sensory neuropathy

21

Pyrazinamide

hepatitis, arthralgia

22

ethambutol

Optic neuritis

23

Meningeal TB Mx

Head CT
Examinations for meningism - Kernigs and Brudinski's

RIPE - 2 months
Rifampicin and isoniazid - 10 months
Dexamethasone

24

Risk factors

Immigrant
IVDU
HIV
Immunocompromised
Homeless
Close contacts
Young adults and elderly