Allergic bronchopulmonary aspergillosis

Question 1

Allergic bronchopulmonary aspergillosis : Organism

Answer 1

• Aspergillus fumigatus is a fungi which is normally found in soil, mould
• Aspergillis spores are normally found in the atmosphere and commonly inhaled.
• Immunocompetent patients are able to defend against colonisation of the lungs

Aspergillus spores on a culture does not implicate them in disease

Question 2

Allergic bronchopulmonary aspergillosis : Definition

Answer 2

• An allergic hypersenstivity reaction to Aspergillus fumigatus elements colonise the bronchi in an immunocompetent person in response to mould exposure or contaminated air.
• NOT a fungal infection of the lungs

Question 3

ABA : Risk factors

Answer 3

• History of Atopy - hypersensitivity to allergens is predisposed
• Asthma
• Cystic fibrosis

Question 4

ABA : Risk factors - CF and Asthma pathophysiology

Answer 4

1. • concurrent mucus hyper-secretion and impaired mucociliary clearance
2. • Increased trapping of pores with reduced clearance
3. • Encourages germination and release of antigenic proteins which provoke and immune response

Question 5

ABA : Pathophysiology

Answer 5

1. • Aspergillus fumigatus antigens are inhaled into the airways
2. • Immune system trigger a hypersensitivity response, involving eisonophils and produced IgE + IgG antibodies against the spore antigens
3. • Intense air way inflammation : damage of elastic fibres and triggers excessive mucous production
4. • Mucus plugs filled with eisenophills and inflammatory tissue form

Question 6

ABA : Complication

Answer 6

Chronic infections overtime - lead to bronchiectasis } complication

Question 7

ABA : Clinical features

Answer 7

• Risk factors : asthma, atopy, CF
• Acute Asthma exacerbation
• Increased purulence of mucus in CF

Question 8

ABA : Investigations

Answer 8

1. Skin test for Aspergillus fumigatus sensitivity
   - initial screening however is non specific
2. Serum total IgE -
   * Significantly higher in patients with ABPA than those with asthma
3. Aspergillus-specific IgE
   * Very specific if high combined with serum total IgE
4. FBC with peripheral eosinophil count
   * Eisenophillia secondary to autoimmune hypersensitivity response
5. CXR : mucus plugging, bronchiectasis and infiltrates
6. CT

Question 9

ABA : Management

Answer 9

1 . Oral corticosteroid
- immunosuppressant of inflammation during exacerbation

2 . Environmental control
- reduce exposure to fungi anitigen

3 . Antifungal
- Although non invasive fungal infection, eradication of the fungus may modify disease caused by the hypersensitivity reaction