TB Flashcards
Define: granuloma
- Types
Organized collection of macrophages.
May contain additional cells depending on the cause.
- Caseous= contains necrosing material surrounded by macrophages and lymphocytes.
- Non-necrotising= non caseum
- Fibrotic= mainly composed of fibroblasts.
Define: Ghon focus, complex, Ranke complex
Initial area of granulomatous inflammation that can be seen on CXR when it calcifies.
Complex occurs when there is a focus AND lymphadenopathy.
Ranke complex= calcified Ghon’s complex
Latent TB
- Define
- Features
TB bacteria that is contained in granuloma and not actively replicating.
- Bacteria levels are low enough to not cause clinical symptoms.
Features
- Non-infectious
- Negative sputum, CXR
- Positive culture
Active TB
- Definition
- Features
TB bacteria that is actively multiplying. Managed to breakdown granuloma and replicate.
Features
- Symptomatic: cough, fever, weight loss
- Positive culture, sputum, CXR signs
- Infectious before treatment
Causative agents of TB
Most common= Mycobacterium tuberculosis
Other= M bovis
Examples of non TB mycobacteria (3)
M. leprae
M avium
M kansasii
Risk factors for TB (6)
HIV
- Especially in areas where prevalence is high (sub-saharan africa)
Overcrowded areas
Malnutrition
Poverty
People: IVDU
Genetic susceptibility.
Transmission and pathophysiology of TB
Spread via aerosol/ droplets.
- inhaled and enter alveoli
5+ bacteria can cause infection.
- Bacteria is engulfed by macrophage and causes intracellular infection.
Clinical features of active TB (6)
Cough, productive
- 1/3 have haemoptysis
Weight loss
Fever
Night sweats
Fatigue
Loss of appetite
TB complications
Meningitis
Sepsis
Pleural effusion/ Empyema
Dissemination
- Pott’s disease (spine)
Miliary TB
- Define
- Presentation
Severe TB
- Widespread dissemination causing small lesions.
- Spreads to extra-pulmonary organs: liver, spleen, kidneys
Presents
- Spleno/hepatomegaly
TB meningitis
- Definition
- Presentation
Severe complication of TB that has spread through the blood
Presentation: meningism
- Headache, vomitting
- Drowsiness
- Photophobia, neck pain
- CNS palsy
- Seizure
TB treatment
- 2 months of 4 drugs including
- rifampicin
- isoniazid
- pyrazinamide
- ethambutol - 4 months on 2 drugs, as mentioned above.
XDR- TB
Resistance to additional 3- classes of second line drugs
- Associated with cumulative duration of past treatment with 2nd line TB drugs
causes of drug resistant TB
Drug resistance
MTB= resistance to rifampicin and isoniazid
Non-compliance with medicine
Low quality medication
