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Week 228 - Fungal Infections > Aspergillosis > Flashcards

Aspergillosis Flashcards

1
Q

What are most fungi?

A

Saprophytes

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2
Q

When are fungi most likely to cause infections?

A

When immunity is reduced

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3
Q

What are the most common fungal infections?

A

Dermatophyte infections

  • ringworm of the nails
  • tinea cruris
  • athlete’s foot
  • tinea corporis
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4
Q

Which areas of the body does candida affect?

A

Oral cavity

Oesophagus

Vagina / Glans penis (balanitis)

Systemic (only in immunosuppressed)

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5
Q

When often precedes an oesphageal candida infection?

A

ABX, Steroids, Immunosuppressants use

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6
Q

What is aspergillus?

A

A mould - i.e. grows in the form of hyphae (multicellular filaments), can also exist in spore form (unicellular)

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7
Q

What condition is unique to aspergillus inside the body?

A

Always exists as hyphae due to anaerobic conditions

- except in aspergillomae

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8
Q

What are the two most common fungal pathogens in humans?

A
  1. Candida

2. Aspergilluss

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9
Q

What toxin produced by aspergillus causes hepatocellular carcinoma?

A

Aflatoxin

- produced by aspergillus growing on mouldy peanuts

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10
Q

What are the 4 main presentations of aspergillosis disease?

A

Allergic bronchopulmonary aspergillosis (hypersensitivity pneumonitis)

Aspergilloma

Chronic granulomatous aspergillus pneumonia

Invasive aspergillosis

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11
Q

Describe the pathophysiology of hypersensitivity pneumonitis (allergic broncho-pulmonary aspergillosis)

A

Presence of antigen (e.g. aspergillus) in bronchi/alveoli

Produces immune mediated response via 2 pathways

  • type 3 hypersensitivity reaction
  • type 4 hypersensitivity reaction
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12
Q

Describe a type 3 hypersensitivity reaction?

A

Immune complex formation
= extensive cross linking by Abs and antigens
- Antiboies => mainly Th2 and B cell mediated

Neutrophil degranulation causing increased vascular permeability

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13
Q

Describe a type 4 hypersensitivity reaction?

A

Delayed hypersensitivity reaction
= cell mediated immune memory response
- mainly Th1 cells and macrophages

Granulomas and inflammatory damage result

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14
Q

What does allergic broncho-pulmonary aspergillosis result in?

A

Bronchospasm

Mucous plugging

Bronchocentric inflammation with progressive bronchiectasis, smooth muscle hypertrophy and pulmonary fibrosis

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15
Q

What are the risk factors of allergic-broncho pulmonary aspergillosis?

A

Underlying lung disease, e.g. asthma, CF, COPD

- clearance of spores more diffucult

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16
Q

What are the symptoms and signs of allergic broncho-pulmonary aspergillosis?

A

Develops 4-6 hours post-exposure

Fever
Dyspnoea
Cough - productive, occasionally haemoptysis
Wheeze

Sx alleviated after spell without exposure

17
Q

What are the investigations of allergic broncho-pulmonary aspergillosis?

A

Peak flow / spirometry

CXR - infiltrates and consolidation

Allergy testing

Broncheolar lavage => raised WCC, Eosinophilsand aspergillus

Bloods => raised IgE, aspergillus Antibodies

VATS biopsy => alveoli filled with macrophages and lymphocytes

18
Q

How should allergic broncho-pulmonary aspergillosis be treated?

A

Prevent further exposure to allergen

Oral corticosteroids, e.g. prednisolone
+/- oral antifungals (itraconazole)

Immunosuppresants, e.g. cyclophosphamide (if necessary)

19
Q

What is the pathophysiology of an aspergilloma?

A

Pre-existing cavity in lung parenchyma

Colonised by aspergillus, which forms ‘mycetoma within cavity’

Usually not invasive, but may produce erosion with haemoptysis
- due to oxalic acid released by hyphae

20
Q

What are the risk factors for an aspergilloma?

A

previous cavitating disease

  • old TB
  • abscess
  • bronchiectasis
  • chronic intersitial lung disease
21
Q

How do aspergillomas often present?

A

Often asymptomatic

Haemoptysis occurs in 50%

  • recurrent
  • sometimes life-threatening

Non-specific = weight loss, lethargy

Solitary mass on CXR

Fever and cough less common

22
Q

What needs to be done to investigate an aspergilloma?

A

CXR = solitary pulmonary mass (classically)
- crescent of air around mass may be noticeable

Biopsy/fine needle aspiration
- pink necrotic centre, rim of active hyphae

Sputum - hyphae on cytology, culture

Bloods - aspergillus antibodies mildly raised

23
Q

How should aspergillomas be treated?

A

Conservative if stable
- Anti-fungals are no good!!!

Surgical resection if troublesome bleeding

Bronchial artery embolisation if severe bleeding

24
Q

Describe the pathophysiology of chronic necrotising pulmonary aspergillosis?

A

Occurs in those with mild-moderate immunosuppression

Aspergillus colonises bronchi/alveoli
- may invade locally

Th1/macrophage dominated immune response not able to clear infection => granulomas => necrosis and cavitation

25
Q

What are the risk factors for chronic necrotising pulmonary aspergillosis?

A

Mild-to-moderate immunosuppression, e.g. alcoholism, Steroid treatment

Pre-existing lung disease, COPD

26
Q

Describe the presentation for chronic necrotising pulmonary aspergillosis?

A

Fever, cough, night sweats, weight loss, consolidation

27
Q

What investigations are needed for chronic necrotising pulmonary aspergillosis?

A

CXR - infiltrates and consolidation

Sputum culture - aspergillus shown in 35%

Broncho alveolar lavage/needle biopsy - shows aspergillus in 65%, Galactomannan assay

Bloods - aspergillus antibodies

28
Q

What treatment is needed for chronic necrotising pulmonary aspergillosis?

A

Antifungals
- voriconazole, itraconazole, amphotericin

Eliminate immunosuppression

Surgical resection if unresponsive

29
Q

Describe the pathophysiology for invasive aspergillosis?

A

Occurs in immunosupprssed

Aspergillus colonises in bronchi/alveoli and invades interstitium -> invasion of bloodstream

30
Q

What are the risk factors for invasive aspergillosis?

A

Immunocompromised esp. those with neutropaenia

- HIV, renal organ transplant, steroids/chemo

31
Q

What are the Sx of invasive aspergillosis?

A 
Fever and night sweats
Cough
Dyspnoea
Pleuritic pain
Disseminated Sx - depending on involved organs
32
Q

What are the investigations for invasive aspergillosis?

A

CXR

Indentification of aspergillus

  • sputum
  • broncho-alveolar lavage
  • biopsy

Serology

33
Q

What is the treatment for invasive aspergillosis?

A

Antifungals - IV Voriconazole
- Amphotericin (against zygomycetes) - well tolerated

Reduce immunosuppression

  • discontinue suppresants
  • GCSF

Week 228 - Fungal Infections (3 decks)

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