Tuberculosis

Question 1

Define tuberculosis

Answer 1

Granulomatous disease caused by Mycobacterium tuberculosis.

Primary TB: initial infection may be pulmonary or more rarely GI

Miliary TB: disseminated TB via blood

Post-primary TB: caused by reinfection or reactivation

Question 2

Explain the aetiology/ risk factors of tuberculosis

Answer 2

Causes: Mycobacterium tuberculosis is an intraC organism that lives in the macrophages’ phagosomes. Cells try to kill the phagosomes with ROS but the bacterium survives. This recruits T, B cells and macrophages and fibriblasts that form granulomas.

Risk factors:

• HIV infection
• immunocompromised
• DM, ETOH, smoke
• underyling lung dx, silicosis and industrial etc
• overcrowding
• malnutrition
• IVDU
• endemic areas, travel
• prisons, refugees, health care workers

Question 3

Summarise the epidemiology of tuberculosis

Answer 3

Annual mortality: 3 million (95% in dev countries)

UK incidence: 6000/ annum

Asian immigrants are the highest risk group in UK

Question 4

Recognise the presenting symptoms and signs of pulmonary tuberculosis

Answer 4

Primary TB:

• ASYMPTOMATIC
• fever, malaise
• cough
• wheeze
• erythema nodosum
• phlyctenular conjunctivitis

Miliary TB:

• fever, wt
• meningitis
• yellow caseous tubercles spread to other organs

Post-primary TB:

• wt
• SOB
• cough
• sputum
• haemoptysis
• pleuritic chest pain
• pleural effusion (orpthopnoea)
• collapse
• consolidation
• fibrosis
• night sweats

Question 5

Recognise the presenting symptoms and signs of non-pulmonary tuberculosis

Answer 5

LNs: suppuration of cervical LNs -> abscesses or sinuses

CNS: meningitis, tuberculoma

Skin: lupus vulgaris (red.brown glistening plaques)

Heart: pericordial effusion, constrictive pericarditis

GI: subacute obstr, change in bowel, wt, peritonitis, ascites

GU: UTI symptoms, renail failure, epididymitis, endometrial involvement, infertility

Adrenal insuff

Bone/Joint: osteomyelitis, arhritis, vertebral collapse (pott’s disease), spinal cord compression from abscesses

Question 6

Identify appropriate investigations for tuberculosis

Answer 6

Sputum, pleural, bronchial washings - MCS and acid-fast bacilli test (AFB - non specific)

Bloods: CRP, FBC

CXR:

• primary: peripheral consolidation, hilar LNs
• miliary: fine shadowing
• post-primary: upper lobe shadowing, streaky fibrosis and cavitation, calcification, pleural eff, hilar LNs

Tuberculin Mantoux test:

• check exposure to MT or BCG
• purified protein derivative intradermal
• erythema occurs 72h

Heaf test:

• drop of PPD then gun it in
• grade papule 3-7 days later

Interferon gamma tests:

• latent TB

HIV test

CT, LNs, pleural and other organ biopsy