Tuberculosis Flashcards
What type of disease is Tuberculosis?
A chronic recurrent infectious disease
What is the main cause of tuberculosis?
Mycobacterium tuberculosis bacteria
What type of bacteria is mycobacterium tuberculosis?
Acid-fast bacilli (small rod shaped bacteria)
How is Tuberculosis transmitted?
Inhalation of aerosol droplets containing bacterium
How does Tuberculosis typically present?
- Systemic features
- Low-grade fever
- Anorexia
- Weight loss
- Malaise
- Night sweats,
- Clubbing
- Erythema nodosum
What are the different forms of Tuberculosis
Primary
Secondary/reactivation
Miliary
Where in the body can TB affect?
Anywhere in the body (most commonly the lungs)
In who are the lungs typically affected in someone with Tuberculosis?
- Elderly
- Immunosuppressed
- Malnourished
Which lymph nodes are commonly affected in Tuberculosis?
Painless enlargement of Cervical or supraclavicular lymph nodes
What would you see on a chest x-ray in someone with primary tuberculosis?
Patchy consolidation
Pleural effusions
Hilar lymphadenopathy
What would you see on a chest x-ray in someone with reactivated tuberculosis?
Patchy or nodular consolidation with cavitation (gas filled spaces in the lungs) typically in the upper zones
What would you see on a chest x-ray in someone with Miliary tuberculosis?
“Millet seeds” uniformly distributed throughout the lung fields
What are the two tests for an immune response to TB caused by previous, latent or active TB?
- Mantoux Test
- Interferon-Gamma Release Assays (IGRAs)
What are the main investigations for Tuberculosis?
- Fine-needle aspiration
- AFB staining,
- Culture
What is the name of the stain used to test for mycobacterium tuberculosis?
Zeihl-Neelsen stain
What is a positive result from the Ziehl-Neelsen stain?
The stain turns TB bacteria bright red against a blue background
What is the gold standard investigation for active tuberculosis?
Sputum culture
What is the classic x-ray finding of reactivated tuberculosis?
Upper lobe cavitation
What is primary tubeculosis?
A non-immune host is exposed to M. tuberculosis and develops a small lung lesion called a Ghon focus
What happens during primary tuberculosis in someone who is immunocompetent?
The initial lesion (gohn focus) usually heals by fibrosis
What happens during primary tuberculosis in someone with is immunocompromised?
They may develop disseminated disease (miliary tuberculosis).
What is secondary (post-primary) tuberculosis?
Host becomes immunocompromised the initial infection may become reactivated
Where does reactivation usually occcur in someone with secondary tuberculosis?
In the apex of the lungs
Where can extra-pulmonary infection occur in someone with tuberculosis?
Central nervous system
Vertebral bodies
Cervical lymph nodes
Renal
Gastrointestinal tract
What is the most serious complication of tuberculosis?
Tuberculous meningitis
What disease can occur if tuberculosis affects the vertebral bodies?
Pott’s disease
What is the standard therapy for treating active TB?
Initial phase - first 2 months (RIPE)
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
What is the next phase of medical therapy after the initial phase?
Continuation phase- next 4 months
Rifampicin
Isoniazid
What is the management of latent TB?
3 months of isoniazid (with pyridoxine) and rifampicin
OR
6 months of isoniazid (with pyridoxine)
How are patients with meningeal TB treated?
They are treated for longer (at least 12 months) with the addition of steroids
What is a complication of TB treatment?
Immune reconstitution disease
When does immune reconstitution disease typically occur after starting treatment for TB?
3-6 weeks after starting treatment
How does immune reconstitution disease present?
Enlarging lymph nodes
What are the main side effects of izonisaid?
peripheral neuropathy: prevent with pyridoxine (Vitamin B6)
hepatitis, agranulocytosis
liver enzyme inhibitor
What are the main side effects of rifampicin?
potent liver enzyme inducer
hepatitis
orange secretions
flu-like symptoms
What are the mian side effects of pyrazinamide?
Hyperuricaemia causing gout
Arthralgia
Myalgia
Hepatitis
What are the mian side effects of ethambutol?
Optic neuritis: check visual acuity before and during treatment
What should you check before and during treatment due to ethambutol?
Visual acuity due to optic neuritis
What does the Mantoux test involve?
Purified protein derivative (PPD) injected intradermally
What does a <6mm result from the mantoux test suggest?
Negative — give BCG if they are unvaccinated
What does a 6-15mm result from the mantoux test suggest?
positive -should not be given BCG; may be due to previous TB infection or BCG
What does a >15mm result from the mantoux test suggest?
strongly positive- suggests tuberculosis infection
How does Tb spread throughout the body?
Via the lymphatic system
What is the inflammatory response in TB?
Type 4 hypersensitivity reaction
What happens in the body in TB?
Granulomas containing the bacteria form around the body
What is a gohn focus composed of?
Tubercle-laden macrophages
What is a gohn complex?
Combination of a Ghon focus and hilar lymph nodes
