Tuberculosis Flashcards
Define tuberculosis
Granulomatous disease caused by Mycobacterium tuberculosis
Primary TB: Initial infection may be pulmonary or (more rarely) gastrointestinal
Miliary TB: results from haematogenous dissemination of
TB
Post-Primary TB: caused by reinfection or reactivation
Explain the aetiology/risk factors of tuberculosis
Mycobacterium tuberculosis is an intracellular organism
It survives after being phagocytosed by macrophages
Summarise the epidemiology of tuberculosis
Annual mortality = 3 million (95% in developing countries)
Annual UK incidence = 6000
Asian immigrants are the highest risk group in the UK
Recognise the symptoms and signs of Primary and Miliary tuberculosis
Primary TB: Mostly ASYMPTOMATIC Fever Malaise Cough Wheeze Erythema nodosum Phlyctenular conjunctivitis
Miliary TB Fever Weight loss Meningitis Yellow caseous tubercles spread to other organ
Recognise the symptoms and signs of Post-primary tuberculosis
Fever/night sweats Malaise Weight loss Breathlessness Cough Sputum Haemoptysis Pleuritic chest pain Signs of pleural effusion Collapse Consolidation Fibrosis
Recognise the symptoms and signs of non-pulmonary tuberculosis
Occurs mainly in the immunocompromised
Lymph Nodes - Suppuration of cervical lymph nodes leading to abscesses or sinuses
CNS - meningitis, tuberculoma
Skin - Lupus vulgaris (jellylike reddish-
brown glistening plaques)
Heart - pericardial effusion, constrictive pericarditis
GI - Subacute obstruction, Change in bowel habit, Weight loss, Peritonitis, Ascites
Genitourinary - UTI symptoms, Renal failure, Epididymitis,
Endometrial or tubal involvement, Infertility
Adrenal insufficiency
Bone/Joint - osteomyelitis, arthritis, vertebral collapse (Pott’s disease), spinal cord compression from an abscess
Identify appropriate investigations for tuberculosis
Sputum/Pleural Fluid/Bronchial Washings - MC&S
NOTE: culturing TB takes a long time (around 6 weeks)
Tuberculin Tests - Positive if the patient has had previous exposure to M. tuberculosis or BCG.
CXR Primary Infection Peripheral consolidation Hilar lymphadenopathy Miliary Infection Fine shadowing
Post- Primary Upper lobe shadowing Streaky fibrosis and cavitation Calcification Pleural effusion Hilar lymph adenopathy
HIV Testing
CT, lymph nodes, pleural biopsy, sampling of other affected systems
What are the tubercullin tests?
Mantoux Test - A purified protein derivative (PPD) is injected intradermally. Erythema occurs after 72 hours
Heaf Test - Place a drop of PPD on the forearm
Fire a spring -loaded needle gun
Check again after 3- 7 days
Graded according to papule size and vesiculation
Interferon Gamma Tests
Useful in latent TB
Exposure of host T cells to TB antigens leads to release of interferon
