From the Guidelines
Diagnosis of aspergillosis should be based on a combination of clinical evaluation, imaging, and laboratory tests, with a strong emphasis on serum biomarkers such as galactomannan antigen testing and PCR for Aspergillus DNA, as recommended by the most recent guidelines 1. The diagnostic approach typically begins with a thorough clinical assessment looking for risk factors such as immunosuppression, prior lung disease, or prolonged neutropenia.
Key Diagnostic Criteria
- Radiological studies, particularly chest CT scans, are essential for showing characteristic findings like the "halo sign" in invasive pulmonary aspergillosis.
- Laboratory testing includes:
- Direct microscopy and culture of respiratory specimens (sputum, bronchoalveolar lavage fluid), which remain the gold standard for identification.
- Serum biomarkers, with galactomannan antigen testing being most widely used (positive at index ≥0.5 in serum or ≥1.0 in bronchoalveolar lavage fluid) 1.
- The 1,3-β-D-glucan test, which is less specific but can support diagnosis.
- PCR testing for Aspergillus DNA, which is increasingly available and offers rapid results.
- Histopathological examination of tissue samples showing septate hyphae with 45° angle branching is definitive but requires invasive procedures.
Additional Testing for Allergic Bronchopulmonary Aspergillosis
- Total IgE levels (typically >1000 IU/mL) and Aspergillus-specific IgE antibodies should be included in the diagnostic workup for allergic bronchopulmonary aspergillosis. Early diagnosis is crucial as delayed treatment significantly increases mortality, particularly in invasive forms, highlighting the importance of following the latest guidelines for diagnosis and management of aspergillosis 1.
From the Research
Diagnostic Criteria for Aspergillosis
The diagnostic criteria for Aspergillosis, a fungal infection caused by Aspergillus species, involve a combination of clinical, radiological, and microbiological tests. The following are some of the key diagnostic criteria:
- Galactomannan antigen detection in body fluids, such as blood or bronchoalveolar lavage fluid, is a reliable diagnostic test for invasive aspergillosis 2, 3, 4, 5
- Aspergillus PCR in blood or bronchoalveolar lavage fluid can also be used for diagnosis, although its sensitivity and specificity may vary 3, 6, 4, 5
- Detection of beta-D-glucan in serum can be used as a diagnostic marker for invasive fungal infections, including aspergillosis 4
- Microscopic examination and culture of tissue samples or bronchoalveolar lavage fluid can also be used for diagnosis 6, 5
- Combination of these diagnostic tests can improve the sensitivity and specificity of diagnosis 3, 4
Diagnostic Tests
The following diagnostic tests can be used for Aspergillosis:
- Galactomannan enzyme immunoassay (GM EIA) 2, 3, 4, 5
- Aspergillus PCR 3, 6, 4, 5
- Beta-D-glucan assay (BDG) 4
- Multifungal DNA-microarray (Chip) 4
- Microscopic examination and culture of tissue samples or bronchoalveolar lavage fluid 6, 5
Sample Collection
The following samples can be collected for diagnostic testing: