aspergillus lung disease Flashcards
definition of aspergillus lung disease
Lung disease associated with Aspergillus fungal infection.
aspergillus affects the lung in 5 ways
- asthma
- allergic bronchopulmonary aspergillosis
- aspergilloma (mycetoma)
- invasive aspergillosis
- extrinsic allergic alveolitis
aetiology of aspergillus lung disease
Inhalation of the ubiquitous Aspergillus (usually Aspergillus fumigates) spores can produce three different clinical pictures:
- aspergilloma
- allergic bronchopulmonary aspergillosis (ABPA)
- invasive aspergillus
- asthma- Type I hypersensitivity reaction to fungal spores
aspergilloma
growth of A fumigatus mycetoma ball in a preexisting lung cavity eg post-TB, from sarcoidosis, old infarct or abscess
allergic bronchopulmonary aspergillosis
type 1 and 3 hypersensitivity reaction
progress from bronchoconstriction to bronchiectasis
colonisation of airway usually in asthmatics = IgE and IgG mediated immune response
proteolytic enzymes and mycotoxins released by fungi, CD4/Th2 cells producing IL-4 and IL-5 and mediating eosinophilic inflammation, and IL-8 mediated neutrophilic inflammation = airway damage and central bronchiectasis
invasive aspergillosis
Invasion of Aspergillus into lung tissue and fungal dissemination.
Secondary to immunosuppression (e.g. neutropaenia, steroids, haematopoietic stem cell/solid organ transplantation, AIDS).
RF for invasive aspergillosis
immunocompromise - HIV, leukaemia, burns, Wegener’s, SLE
broad spectrum AB
epidemiology of aspergillus lung disease
uncommon
most common in elderly and immuncompromised
ABPA - Affects 1–5% of asthmatics, 2–25% of CF patients
sx of aspergilloma
asymptomatic
haemoptysis which may be massive
cough
lethargy
weight loss
sx of ABPA
difficult to control asthma
recurrent episodes of pneumonia and wheeze, cough, fever and malaise
sputum - plugs of mucus containing fungal hyphae
dyspnoea
recurrent pneumonia
sx of invasive aspergillosis
dyspnoea
rapid deterioration
septic picture
signs of aspergillosus lung disease
tracheal deviation in large aspergillomas
dullness in affected lung, reduced breath sounds, wheeze in ABPA
cyanosis in invasive aspergillosis
Ix for aspergilloma
CXR - round opacity with crescent of air around it - usually in upper lobes
CT or MRI of CX doesn’t delineate a cavity
cultures of the sputum may be negative if no communication between cavity and the bronchial tree. Also Aspergillus is a common colonizer of an abnormal respiratory tract.
strongly positive serum precipitins;
Aspergillus skin test (30% +ve)
Ix for ABPA
immediate skin test reactivity to aspergillus ag
eosinophilia
raised serum total IgE
raised serum specific IgE and IgG to A. fumigatus or precipitating serum Ab to A. fumigates
positive serum precipitins
CXR
CT - lung infiltrates, central bronchiectasis
lung func tests - reversible airflow limitation, reduced lung vol/gas transfer in progressive cases
aspergillus in sputum
CXR for ABPA
transient patchy shadows
collapse
consolidation
distended mucus-filled bronchi producing tubular shadows (gloved fingers appearance)
signs of complications - fibrosis in upper lobes (similar to TB), parallel-line shadows and rings (bronchiectasis)
Ix for invasive aspergillosis
Detection of Aspergillus in cultures or by histologic examination (septated hyphae with acute angle branching).
BAL
biopsy
serum precipitins
Diagnosis may be made in patients with risk factors, suggestive clinical findings and microscopic evidence of septate hyphae on examination of either bronchoalveolar lavage fluid or sputum or a positive serum galactomannan or beta-D-glucan assay(constituents of Aspergillus cell walls).
CT
CXR - consolidation, abscess
complications of aspergillosis
complications of ABPI
