Tuberculosis Flashcards
What is Tuberculosis?
- Infection with Mycobacterium tuberculosis
What sort of inflammation occurs in TB?
Caseating granulomas
Where in the world is higher risk of TB?
- Asia
- African
- Latin America
TRAVEL Hx
What is primary TB?
First infection of TB
What does primary TB create in the lung?
Gohn’s Focus
What is the name of a Gohn’s Focus in a lymph node?
Gohn’s complex
What is secondary TB?
Reactivated TB
Where does secondary TB most commonly occur?
Lung apex
What type of hypersensitivity is secondary TB?
Type 4 (cell-mediated)
What is latent TB?
Inactive TB (asymptomatic)
What is miliary TB?
TB that is disseminated through the body
How does miliary TB spread?
Lymphohaematogenous
Who is at risk of miliary TB?
- IVDUs
- HIV
- Malnutrition
- Steroid users
What symptoms does TB present with?
- Pleuritic chest pain
- Low-grade fever
- Cough (dry at first and then productive)
- Haemoptysis
- Weight loss
- Night sweats
What are the red flags of TB?
- Night sweats
- Weight loss
What is cutaneous TB?
TB in the skin, most commonly affecting previously sensitised patients who have high immunity
How does cutaneous TB present?
Skin erythema, normally well demarcated but non-specific
What is erythema nodosum?
- Inflammation of subcutaneous fat
- Causes pre-tibial marking- pale erythema/bruising
How would you stain TB?
- Ziehl Nielson (ZN) stain
Why can’t TB be stained with H&E?
TB is acid fast, and wouldn’t show on a normal stain
What other blood test can be used for TB?
Interferon gamma release assay
What would a CXR show for TB?
- Fibronodular opacities +/- cavitation
- A-E (second card)
What is the A-E of a TB CXR?
Alveolar shadowing (batwing) Kerley B lines Cardiomegaly Distribution of vessels to the apices Effusion
What is a Mantoux test?
Tuberculin sensitivity to see latent disease
How long do you wait for a Mantoux result?
2-3 days
How will vaccinated person show on Mantoux?
6-15mm raised bump
How will latent TB show on Mantoux?
15mm+
What MUST you do on diagnosis?
Notify local health team/infectious diseases officer within 3 days
What five drugs are used for TB?
RIPE
- Rifampicin
- Isoniazid and Pyridoxine (B6)
- Pyrazinamide
- Ethambutol
How long are [R,I+p] used for?
6 months
How long are [P,E] used for?
Three months
What are the side effects of R?
OI
- Orange urine and tears
- Induces Cyp450 enzymes
What are the side effects of I?
HIPA
- Hepatitis
- Inhibits Cyp450 enzymes
- Peripheral neuropathy (hence given with B6)
- Agranulocytosis
Why give pyridoxine with isoniazid?
To prevent peripheral neuropathy
What is agranulocytosis?
Drop in inflammatory cells, particularly neutrophils
What do you do if you suspect INH-induced agranulocytosis?
- Admit
- Stop Isoniazid
What are the side effects of pyrazinamide?
HMG
- Hepatitis
- Muscle/joint pain
- Gout (hyperuricaemia)
What is the side effect of Ethambutol?
Optic neuritis
What should you do before beginning ethambutol?
Visual acuity test (to reference and monitor for optic neuritis)
Name three complications of TB.
- Pott’s disease
- Pneumothorax
- Bronchiectasis
What is Pott’s disease and how does it occur?
- TB of the spine
- Haematogenous spread of TB
