Tuberculosis

Question 1

Definition

Answer 1

Granulomatous disease caused by infection with Mycobacterium Tubercolosis.

• Primary: infection in the lungs (or rarely in GI tract)
• Miliary: haematogenous spread of lung/GI infection
• Post primary: caused by reinfection or reactivation

Question 2

Aetiology

Answer 2

M tuberculosis is an intracellular organism which survives after being
phagocytosed within macrophages

Question 3

Epidemiology

Answer 3

Annual mortality 3mn (95% in developing countries).

Incidence in UK 6k py.

Incidence in Asian immigants 30x white Caucasians.

Question 4

Presenting symptoms and signs on physical examination

Answer 4

TB is a multi system disease

• Primary TB: mostly asymptomatic, fever, malaise, cough, wheeze, erythema nodosum and phlyctenular conjunctivitis.
• Miliary TB: Fever, weight loss, pleuritic pain, yellow casous tubercles in other organs ie. Bones, kidney.

• Post primary TB: fever, night sweats, SOB, plauritic pain, cough, sputum,
haemoptysis, pleural effusions.

• Non pulmonary TB: particularly in immunocompromised

• Lymph nodes: suppuration of cervical lymph nodes creating abscesses which may expand to the skin (scrofuloderma)
• CNS: meningitis, tuberculoma
• Skin: lupus vulgaris
• Heart: pericardial effusion, constrictive pericarditis
• GI: peritonitis, ascites
• UT: UTI, infertility renal failure.
• Adrenal: insufficiency
• Bone: osteomyelitis, arthritis

Question 5

Investigations

Answer 5

Sputum/ pleural fluid brushing: microscopy (Ziehl/Neelsen stain), culture (6wk) and sensitivity
Tuberculin tests: positive in previous exposure

Mantoux test: PPD injected intradermally, induration and erythema after 72h

Heaf test: PPD on skin, then fire spring loaded needle gun, read after 3-7d.
Graded according to pauple size.

IFNy test: produced if exposed to TB, very specific so used in conjunction with more sensitive test for diagnosis.

CXR:
• Primary infection: peripheral consolidation and holar lymphadenopathy
• Miliary: fine shadowing
• Post primary: upper lobe shadowing, streaky fibrosis and cavitation, calcification, pleural effusion, hilar lymphadenopathy

HIV testing: often coinfected.

CT, lymph, pleural biopsy: depending on affected sites.

Question 6

Management plan

Answer 6

6-12 month treatment regime (lung / systemic)

Several side effect patient must be made aware of:
• Rifampicin: orange body fluids, enzyme inducer
• Isoniazid: prridoxine deficiency, peripheral neuropathy
• Ethambutol: optic neuropathy
• Pyranzamide: increased urate, arthralgia, hepatotoxicity
• Straptomycin: only used in highly resistant cases (more emerging)

Advice: explain side effects and ensure compliance with full treatment.

Consider steroids for bone, pericardial and brain involvement

Public health: notifiable disease

Prevention: BCG vaccination, 60-80% effective against extrapulmonary TB only.

Question 7

Possible complications

Answer 7

Primary TB: lobar collapse, bronchiectasis, pleural effusion, pneumonic spread, milary disease

Post primary TB: pleural effusion, empyema, aspergilloma, adenocarcinoma,
laryngeal disease, swelling of bronchial lymphatics and airflow obstruction,
haemoptysis, distant spread.

Question 8

Prognosis

Answer 8

Excellent if pulmonary and treated.

Mortality 8% with extrapulmonary disease.