10. Tuberculosis Flashcards
Who are at high risk of getting TB?
Non Uk born/recent migrants HIV Other immunocompromised conditions Homeless Drug users, prison Close contacts Young adults
What is the proper name for TB?
Mycobacterium tuberculosis
Describe the microbiology of TB
No-motile rod-shaped bacteria
Obligate aerobe
Typically, where do TB changes happen in the lung and why?
Right apex as has the most amount of oxygen
How is TB transmitted?
Spread is by respiratory droplets - coughing, sneezing, etc.
Contagious but not easy to acquire infection (need prolonged exposure)
Describe the pathogenesis of TB
- Inhaled aerosols
- Engulfed by alveolar macrophages
- Local lymph nodes
- Primary complex can lead to progression to active disease (primary) or initial containment of the infection
- Containment leads to latent infection
- Heals/self cure or reactivation and post primary TB
What is primary TB?
Has Ghon focus/complex
Usually asymptomatic
What is post-primary TB?
Reactivation or exogenous re-infection
>5 years after primary infection
Symptomatic
Who is at risk of reactivation?
Infection with HIV Substance abuse Prolonged therapy with corticosteroids Immunosuppressive therapy Organ transplant Haematological malignancy Severe kidney disease Diabetes Low BMI
Where can extrapulmonary TB be located?
Larynx Lymph nodes Pleura Brain Kidney Bones and joints
What is military TB?
TB is carried to all parts of body, through bloodstream
What is the pathology of TB?
Caseating granulomata - lung parenchyma, mediastinal lymph nodes
‘Caseous necrosis’
What are the symptoms of pulmonary TB?
Fever Night sweats Weight loss and anorexia Tiredness and malaise Cough Haemoptysis Breathlessness if pleural effusion
What are the signs of pulmonary TB?
Often no chest sings despite CXR abnormality
Maybe crackles in affected area
In extensive disease: signs of cavitation, fibrosis
What are the investigations for TB?
CXR
Sputum - 3 early morning samples
Induced sputum
Bronchoscopy (patients with dry cough)
