Week 228 - Fungal Disease Flashcards
(64 cards)
Week 228 - Fungal Disease: What is pneumocystis jirovecii?
Opportunistic fungal parasite which can cause pneumonia in patients with impaired immune systems, such as those with AIDS or are receiving immunosuppressive drugs.
Week 228 - Fungal Disease: What is often the cause of candida of the oesophagus?
• Often follows a treatment of broad spectrum antibiotics, steroids or other immunosuppression.
Week 228 - Fungal Disease: What is the macroscopic appearance of oesophageal candida?
Soft white plaques.
Week 228 - Fungal Disease: How is oesophageal candida diagnosed? How is it confirmed?
- Endoscopic appearance.
* Confirmed by biopsy or brushings.
Week 228 - Fungal Disease: How might non-invasive aspergillus affect the following individuals, 1) Heavy exposure but normal, 2) Asthma or cystic fibrosis, 3) Pre-existing cavitating lung disease.
1) Hypersensitivity pneumonitis
2) Allergic bronchopulmonary Aspergillosis (ABPA)
3) Colonisation of cavities - mycetoma
Week 228 - Fungal Disease: How would invasive aspergillus affect the immunocompromised?
Invasion of blood vessels and tissues within and outside the lungs.
Week 228 - Fungal Disease: What is the pathological mechanism behind hypersensitivity pneumonitis?
• Combination of a type 3 and type 4 immune hypersensitivity response to a large dose of a number of antigens.
Week 228 - Fungal Disease: What is a type 3 hypersensitivity reaction?
• Antigen and antibody complexes precipitate in tissues which trigger the complement system leading to inflammatory damage.
Week 228 - Fungal Disease: What is a type 4 hypersensitivity reaction?
- T Lymphocytes drive macrophages to cause tissue damage.
* Cell mediated.
Week 228 - Fungal Disease: Give some examples of those at risk to hypersensitivity pneumonitis.
- Pigeon fanciers - Serum, feather, faecal proteins.
- Farmers - Fungi in mouldy hay
- Humidifier fever - Organisms in air conditioning
- Brewers - Aspergillus
- Cheese workers - Aspergillus, Penicillium
Week 228 - Fungal Disease: What are the symptoms of hypersensitivity pneumonitis?
• Dyspnoea • Cough • Fever • Flu like symptoms (Develop 4-6hours after exposure)
Week 228 - Fungal Disease: What would you find on examination and investigation in someone with hypersensitivity pneumonitis?
- Examination - Fine crackles at the end of expiration.
- Chest X-ray - Diffuse reticulo-nodular shadowing.
- CT thorax - Bilateral areas of consolidation and air trapping.
Week 228 - Fungal Disease: What is the treatment for hypersensitivity pneumonitis?
- Prevent further exposure.
* Immunosupression - Reduce bodies excessive T-cell response to antigen.
Week 228 - Fungal Disease: What is ABPA?
- Allergic bronchopulmonary aspergillosis.
* In patients with asthma or cystic fibrosis, that have been exposed to a low dose of airborne aspergillosis.
Week 228 - Fungal Disease: What are the symptoms of allergic bronchopulmonary Aspergillosis (ABPA)?
• Cough, Dyspnoea, (Worsening of asthma), coughing up casts.
Week 228 - Fungal Disease: What is a type 1 hypersensitivity reaction?
• IgE mediated.
- An antigen is presented to CD4+ (Th2) cells, these stimulate B-cells to produce IgE antibodies. These coat mast cells and basophils.
- A secondary exposure to the antigen, causes these sensitised cells to release inflammatory mediators such as histamine and prostaglandins.
Week 228 - Fungal Disease: Asthma is due to which type of hypersensitivity reaction?
• Type I
Week 228 - Fungal Disease: What is the type 3 hypersensitivity reaction to aspergillus?
- Immune complexes form as antibodies bind to proteins from the fungus.
- These activate the complement system leading to inflammation and damage to local tissues.
Week 228 - Fungal Disease: What is the type 4 hypersensitivity reaction to aspergillus?
- Activation of lymphocytes which recruit and activate macrophages.
- The macrophages form granulomas - which cause cell damage.
- This eventually leads to bronchiectasis and fibrosis.
Week 228 - Fungal Disease: What is a granuloma?
Ball of highly active macrophages that cause damage to surrounding tissues.
Week 228 - Fungal Disease: How is ABPA diagnosed?
- Hyphae in sputum
- Blood -eosinophilia, raised IgE, positive antibodies.
- Positive skin test to aspergillus proteins.
- Broncho-alveolar lavage
- Bronchiectasis develops with time - tram line, ring and gloved finger signs.
Week 228 - Fungal Disease: What is the treatment for ABPA?
- Oral steroid to suppress immune mediated damage.
- Management of asthma
- Physiotherapy
- Bronchoscopy to remover plugs if CXR shows collapse lasting more than 7 days.
Week 228 - Fungal Disease: What are some of the cavities that can be colonised by aspergillus?
- Old TB
- Abscess
- Bronchiectasis
- Chronic interstitial lung disease
Week 228 - Fungal Disease: Why does haemoptysis occur in cavitating aspergillus?
Oxalic acid released from the hyphae causes erosion of the blood vessels.
