From the Guidelines
The diagnostic approach for invasive pulmonary aspergillosis (IPA) should include a combination of high-resolution chest CT scanning, bronchoscopy with bronchoalveolar lavage (BAL), and microbiological tests such as galactomannan antigen testing and PCR for Aspergillus DNA, as recommended by the 2017 ESCMID-ECMM-ERS guideline 1. The diagnostic approach for IPA requires a multifaceted strategy to ensure timely and accurate diagnosis.
- High-resolution chest CT scanning is essential for identifying characteristic lesions such as nodules, halo signs, or cavitation, and should be performed in patients with suspected IPA, as recommended by the Infectious Diseases Society of America 1.
- Bronchoscopy with BAL should be performed to obtain samples for culture, microscopic examination, and galactomannan antigen testing, which is crucial for diagnosing IPA, with a BAL optical density index ≥1.0 or serum index ≥0.5 considered positive 1.
- PCR testing for Aspergillus DNA in blood or respiratory samples provides rapid results with high sensitivity and should be considered in conjunction with other diagnostic tests 1.
- Serum beta-D-glucan assay can serve as a supportive test, though it's not specific to Aspergillus, and should be used in conjunction with other diagnostic tests 1.
- When feasible, lung biopsy (transbronchial or surgical) provides definitive diagnosis by demonstrating tissue invasion by septate hyphae with 45° branching characteristic of Aspergillus, and should be considered in patients with suspected IPA, as recommended by the 2017 ESCMID-ECMM-ERS guideline 1. The diagnostic approach should be initiated promptly in high-risk patients (those with prolonged neutropenia, hematologic malignancies, solid organ or stem cell transplantation, or prolonged high-dose corticosteroid therapy) who present with compatible clinical symptoms such as fever, cough, chest pain, or hemoptysis, as early diagnosis is essential to reduce mortality rates, which remain high in immunocompromised patients 1.
From the Research
Diagnostic Approach for Invasive Pulmonary Aspergillosis
The diagnostic approach for invasive pulmonary aspergillosis (IPA) involves a combination of clinical, radiological, and microbiological methods. The following are the key components of the diagnostic approach:
- Clinical evaluation: Identifying risk factors such as prolonged neutropenia, hematopoietic stem cell or solid organ transplantation, inherited or acquired immunodeficiency, administration of steroids or other immunosuppressive agents, and critically ill patients 2.
- Radiological evaluation: Early computed tomography (CT) scan to identify angioinvasive and airway invasive aspergillosis, and to detect minimal changes of IPA 2, 3, 4.
- Microbiological evaluation:
- Point of care tests: Detecting an Aspergillus glycoprotein using a lateral flow assay 2.
Classification of Invasive Pulmonary Aspergillosis
The diagnosis of IPA can be classified into:
- Proven IPA: Irrespective of underlying condition 2.
- Probable IPA: For cancer and severely immunosuppressed patients 2.
- Possible IPA: For critically ill patients 2.
- Putative IPA: Based on clinical, radiological, and microbiological criteria 2, 5.
Diagnostic Values of Galactomannan and PCR Methods
The diagnostic values of galactomannan (GM) antigen and Aspergillus nucleic acid detection methods in bronchoalveolar lavage (BAL) samples have been evaluated 6. The results show that:
- BAL GM levels were significantly higher in high-probable IPA patients compared to non-IPA patients 6.
- The cut-off value for GM in BAL samples was determined as 0.7, with a sensitivity rate of 100% and a specificity rate of 87.9% 6.
- The specificity rates of serum GM and BAL Aspergillus PCR methods were high, but their sensitivity rates were found to be low 6.