TB Flashcards
What is the characterisation of M. Tuberculosis?
- rod shaped gram positive bacillus
- 2-4 by 0.2-0.5 micro meters
How is TB transmitted?
Via the aerosol route
Where does the majority of TB come from?
reactivated disease in individuals previously entering the country with latent TB infection
How is active TB diagnosed?
- History and examination
- Simple blood tests
- Radiology/imaging
- microbiology and histology
Describe the treatment for active TB
- 4 drugs for 2 months - Rifampicin, isoniazid, pyraziamide, Ethanbutamol
- 2 drugs for further 4 months: rifampicin and isoniazid
Describe the treatment for latent TB?
2 drugs for 3 months: rifampicin and isoniazid
OR
1 drug for 6 months: isoniazid
What type of TB is spread throughout the body in the blood?
- miliary TB
What is Tuberculosis?
- mycobacterial infection
- chronic infection described in many body sites
- pathology characterised by delayed (type IV) hypersensitivity (granulomas with necrosis)
What are the main pathogens that cause TB in humans?
- M. tuberculosis
- M. bovis
What is type IV hypersensitivity in TB?
- T cell response causes granulomatous inflammation, tissue necrosis and scarring
What is immunity in TB?
T cell response to organism enhances macrophage ability to kill mycobacteria
Describe primary TB?
- 1st exposure and up to 5 years afterwards
- inhaled organism phagocytose and carried to hilarious lymph nodes
- immune activation leads to a granulomatous response in nodes usually with killing of organism
Describe secondary TB?
- reinfection or reactivation of disease in a person with some immunity
- disease tends to remain localised, often in apices of the lung
- can progress to spread by airways and/or bloodstream
describe the tissue changes that occur in primary TB?
- small focus in periphery of mid zone of lung
- large hilar nodes
Describe the tissue changes that occur in secondary TB?
- fibrosing and caviating apical lesions
