Aspergillosis
Introduction
- Aspergillus fumigatus is the most common cause of aspergillosis.
Important morphological Feature
- Aspergillus is a mould with septate
- Dichotomous branching hyphae.
Important cultural characteristics
- Ability of A. fumigatus to grow at 45oC helps to distinguish it from other species.
Mode of transmission
- Inhalation of Aspergillus spores (Conidia).
- Not a contagious disease
Clinical manifestations of aspergillosis
1. Allergic bronchopulmonary aspergillosis:
- occurs in patients with preexisting asthma or cystic fibrosis.
2. Endobronchial saprophytic pulmonary aspergillosis (Aspergilloma):
- In a patient with prior chronic lung disease
- Such as tuberculosis, sarcoidosis, bronchiectasis or histoplasmosis.
3. Invasive Aspergillosis
- Develops as an acute pneumonic process
- With or without dissemination in the immunocompromised patients
- Most common among patients with acute leukemia and recipient of tissue transplants
- CT finding→ Halo sign and crescent sign
4. Allergic sinusitis may take following forms :
- Most common cause of fungal sinusitis
- A fungal ball
- Chronic fibrosing granulomatous inflammation
- Allergic fungal sinusitis
- Acute fulminant sinusitis
5. Aspergillosis in AIDS
- Most commonly infect lung
- CD4 + cell count is < 50/ L
- Most common radiologic finding:
- Bilateral diffuse or focal pulmonary infiltrates with a tendency to cavitate.
6. Extrapulmonary
- Otomycosis
- Acute fungal otitis externa,
- Fungal or yeast infection of the external auditory meatus.
- Aspergillus Niger 90% cases
- Endophthalmitis
- Satellite lesions in eye
- Keratitis
- Endocarditis
Hypersensitivity Reaction to Aspergillus
- Hypersensitivity Lung diseases that result from exposure to A. Fumigatus allergens include:
- Bronchial Asthma, ABPA and Extrinsic Allergic Alveolitis (Hypersensitivity Pneumonitis)
In Atopic Individual
- Allergic Bronchial Asthma and ABPA
- The immune response is IgE mediated
In Non atopic Individuals
- Extrinsic Allergic Alveolitis (Hypersensitivity penumonitis)
- Not IgE mediated.
- May be mediated(type IV) or immune complex (Type III) reactions.
Diagnostic features of allergic bronchopulmonary aspergillosis (ABPA)
Main diagnostic criteria
- Clinical history of Asthma
- Pulmonary infiltrates (transient /fleeting or fixed)
- Peripheral eosinophilia (> 1000 /,uL)
- Immediate skin reactivity to Aspergillus antigen (wheal and flare response)
- Serum precipitins to A. fumigatus
- Elevated serum IgE levels(>100Ong/ml)
- Central /proximal bronchiectasis
Secondary diagnostic criteria
- History of brownish plugs in sputum
- Identification/culture of A., fumigatus from sputum
- Late skin reactivity to aspergillus antigen – CMDT
- Elevated IgE (and IgG) class antibodies specific for A. fumigatus
Histopathology
- Microscopically, the fungus may appear as a tangled mass within the cavity.
- The organisms are identified by their characteristic morphology—
- Thin septate hyphae with dichotomous branching at acute angles
- Stain positive for fungal stains such as PAS and silver impregnation technique.
- The wall of the cavity shows chronic inflammatory cells.
Treatment
- First choice drug for aspergillosis :
- Voriconazole/Amphotericin B
- Second choice drug for aspergillosis
- ltraconazole
- Fungus ball
- Lobectomy
- Allergic bronchopulmonary aspergillosis
- A short course of glucocorticoids
Exam Question
Introduction
- Aspergillus fumigatus is the most common cause of aspergillosis.
- Aspergillus is a mould with septate
- Dichotomous branching hyphae.
- Ability of A. fumigatus to grow at 45oC helps to distinguish it from other species.
- Not a contagious disease
Clinical manifestations of aspergillosis
1. Allergic bronchopulmonary aspergillosis:
- occurs in patients with preexisting asthma or cystic fibrosis.
2. Endobronchial saprophytic pulmonary aspergillosis (Aspergilloma):
3. Invasive Aspergillosis
4. Allergic sinusitis
- Most common cause of fungal sinusiti
5. Aspergillosis in AIDS
6. Extrapulmonary
- Otomycosis
- Aspergillus Niger 90% cases
- Endophthalmitis
- Satellite lesions in eye
Hypersensitivity Reaction to Aspergillus
- Bronchial Asthma, ABPA and Extrinsic Allergic Alveolitis (Hypersensitivity Pneumonitis)
In Atopic Individual
- Allergic Bronchial Asthma and ABPA
- The immune response is IgE mediated
In Non atopic Individuals
- Extrinsic Allergic Alveolitis (Hypersensitivity penumonitis)
- Not IgE mediated.
- May be mediated(type IV) or immune complex (Type III) reactions.
Diagnostic features of allergic bronchopulmonary aspergillosis (ABPA)
Main diagnostic criteria
- Clinical history of Asthma
- Pulmonary infiltrates (transient /fleeting or fixed)
- Peripheral eosinophilia (> 1000 /,uL)
- Immediate skin reactivity to Aspergillus antigen (wheal and flare response)
- Serum precipitins to A. fumigatus
- Elevated serum IgE levels(>100Ong/ml)
- Central /proximal bronchiectasis
Secondary diagnostic criteria
- History of brownish plugs in sputum
- Identification/culture of A., fumigatus from sputum
- Late skin reactivity to aspergillus antigen – CMDT
- Elevated IgE (and IgG) class antibodies specific for A. fumigatus
Histopathology
- Microscopically, the fungus may appear as a tangled mass within the cavity.
- The organisms are identified by their characteristic morphology—
- Thin septate hyphae with dichotomous branching at acute angles
- Stain positive for fungal stains such as PAS and silver impregnation technique.
- The wall of the cavity shows chronic inflammatory cells.
Treatment
- First choice drug for aspergillosis :
- Voriconazole/Amphotericin B
- Second choice drug for aspergillosis
- ltraconazol
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