TB Flashcards
What bacteria is TB caused by?
Mycobacterium tuberculosis
What staining is used in the culture of TB?
Zeihl-Neelsen stain (turns the bacilli red against a blue background)
What is latent TB?
The immune system encapsulates the bacteria and stops progression of the disease
What is miliary TB?
Disseminated and severe disease occurs as the immune system cannot control the infection
What is secondary TB?
When latent TB reactivates, and in infection develops
What are the risk factors for TB?
Close contact with active TB
Immigrants from areas with high TB prevalence
Immuncompromised
Homelessness
IVDU
Silicosis (impaires macrophage function)
What are the symptoms of TB?
Cough
Haemoptysis
Lethargy
Fever
Night sweats
Weight loss
Lymphadenopathy
Erythema nodosum
What is Mantoux screening?
The mantoux test involves injecting tuberculin into the intradermal space on the forearm (to diagnose latent TB)
- More than 5mm of induration is a positive result
What needs to be done to exclude an active infection in someone who is Mantoux positive?
Sputum culture to assess for active TB
What is seen on CXR in primary TB?
Patchy consolidation
Pleural effusions
Hilar lymphadenopathy
What is seen on CXR in reactivated TB?
Patchy or nodular consolidation with cavitation, typically in the upper zones
What is seen on CXR in disseminated miliary TB?
Millet seed appearance (many small 1-3mm nodules)
What culture samples are needed for the diagnosis of active TB?
Sputum culture (3 separate samples are collected)
Mycobacterium blood cultures
Lymph node aspiration or biopsy
NAAT is performed on the samples
What is the treatment of latent TB?
Isoniazid and rifampicin for 3 months
OR
Isoniazid for 6 months
What is the treatment of active TB?
Rifampicin for 6 months
Isoniazid for 6 months
Pyrazinamide for 2 months
Ethambutol for 2 months
