Tuberculosis Flashcards
What is the causative organism of Tuberculosis?
Mycobacterium tuberculosis
How is TB spread?
Most commonly by inhalation of infected droplets
Describe primary tuberculous infection
Macrophages in lung engulf organisms, carry to hilar lymph nodes (can disseminate) Small granulomas (tubercles) form to contain mycobacteria
What are the possible outcomes of primary tuberculous infection?
Spontaneous healing of granulomas and elimination of bacteria (80%)
Bacteria persist, disease becomes dormant
Progression to active TB
What is miliary TB?
Widely disseminated TB occurring when primary infection spreads through bloodstream
What is secondary TB?
Reactivation of dormant M. tuberculosis
Often precipitated by impaired immune function
How does primary TB present?
Often asymptomatic
How does secondary TB present?
Early sx non-specific - Malaise, night sweats, anorexia, wt loss
Late sx - Productive mucoid cough, repeated small haemoptysis, pleural pain
Pneumonia/PE
Fever, apical creps
Clubbing
How does respiratory TB present?
Chronic, productive cough
Purulent/bloodstained sputum
What factors can predispose a patient to TB?
Close contact w/ TB patients South Asian/Sub-Saharan ethnicity Homeless, alcoholics, drug abusers Immunocompromised Elderly patients Age
How should suspected active pulmonary TB be investigated?
Sputum samples - Microscopy, PCR, Culture
Bronchoscopy/Bronchoalveolar lavage
CXR
What signs of TB are present on a CXR?
Upper lobe cavitation
Pleural effusions
Lymphadenopathy
What is the histological hallmark of TB?
Presence of caseating granuloma
What staining should be performed during MC&C?
Acid Fast Bacilli
What are the consequences of pulmonary TB?
Lobar collapse
Bronchiectasis
Pleural effusion
Pneumonia
