What causes TB?
- M. tuberculosis
* M. bovis
What is the pathology of TB?
Primary infection
- Localised lung lesion
- Heals with development of specific immunity
- Asymptomatic in 90% of patients
- Can be haematogenous spread
Post-primary disease
- Reactivaton of persisting mycobacteria
- Much greater immune response
- Usually symptomatic
What is active TB?
- Containment by the immune system is inadequate
- Can arise from primary infection or latent infection
What is latent TB?
- Infection without disease due to immune system containment -> granuloma formation - Contains bacterial growth and spread
What are the systemic symptoms of TB?
- Weight loss
- Night sweats
- Anorexia
- Fevers
What are the pulmonary symptoms of TB?
- Cough +/- sputum
- Haemoptysis
What are the lymph node symptoms of TB?
- Painless lymphadenopathy
- Node is firm and not acutely inflamed
What are the pleuritic symptoms of TB?
Pleuritic pain
What are the bone symptoms of TB?
- Progressive bone/joint pain
- Swelling
What are the GI symptoms of TB?
- Colicky abdominal/pelvic pain
- Constipation
- Vomiting
- Bowel obstruction (bowel wall thickening)
What are the genitourinary symptoms of TB?
- Sterile pyuria (white cells in urine and absence of bacteria)
- Dysuria
- Frequency
- Loin pain
- Haematuria
- Strictures
- Infertility
- Gential ulceratiob
What are the CNS symptoms of TB?
- Headache
- Vomiting
- Irritability
- Confusion
- CN abnormalities
- Meningitis
What are the cardiac symptoms of TB?
- Pericarditis
- Pericardial effusion +/- constrictive pericarditis
What are the skin symptoms of TB?
- Erythema nodosum
- Lupus vulgaris
What would a CXR show in primary disease?
- Primary focus
What would a CXR show in post-primary disease?
- Upper lobe consolidation
- Apical segment lower lobe
- Cavitation
- Volume loss
- Lymphadenopathy
- Pleural effusion
- Pneumothorax
- Miliary TB
What is miliary TB?
• Haematogenous dissemination leads to the formation of discrete foci (millet seeds) uniformly distributed throughout the lung fields
What investigations would you do for TB?
- CXR
- ESR/CRP
- HIV test
- LFTs
- Sputum culture
- Ziehl-Neelsen Stain
- Serous fluid cytology
- PCR
- Urinalysis
Why would you look at LFTs in TB?
Medications are hepatotoxic so need a baseline before starting treatment
How would you detect latent TB?
- BCG scar
- Mantoux test
- Interferon gamma releasing assay (IGRA)
- CXR
Who is required to be screened for TB before coming into the UK?
People from a high-risk country who apply for a UK visa for > 6 months
Who cannot have the BCG vaccine?
- Immunocompromised
- HIV +ve patients
