From the Guidelines
Bronchoalveolar lavage (BAL) findings in fungal infections typically include the presence of fungal elements, increased inflammatory cells, and specific biomarkers, with elevated galactomannan levels being a key finding, as recommended by the American Thoracic Society in 2019 1. Here are the key findings:
- Fungal elements: Hyphae, pseudohyphae, or yeast forms may be visible under microscopy.
- Increased neutrophils and eosinophils: These inflammatory cells are often elevated in response to fungal infections.
- Elevated galactomannan levels: A biomarker specific for Aspergillus species, with a recommended threshold for positivity of OD > 0.5, as suggested by the Infectious Diseases Society of America in 2016 1.
- Positive (1,3)-β-D-glucan test: A non-specific marker for various fungal infections.
- Culture growth: Fungal species may be isolated and identified through culture techniques.
- PCR detection: Molecular methods can identify fungal DNA.
- Cytokine profile changes: Elevated levels of certain cytokines like IL-8 and TNF-α. These findings help diagnose fungal infections and guide treatment decisions, as outlined in the guidelines for the management of fever and neutropenia in children with cancer and/or undergoing hematopoietic stem-cell transplantation in 2012 1. However, results should be interpreted in conjunction with clinical presentation and other diagnostic tests for accurate diagnosis and management. The use of BAL with GM testing is strongly recommended in patients suspected of invasive fungal diseases, including those with a negative serum GM but strong risk factors for invasive aspergillosis or positive serum GM but confounding factors for false-positive GM results, as stated by the American Thoracic Society in 2019 1. In terms of the procedure, BAL is usually performed in the segmental or subsegmental bronchus of the most affected area of the lung based on a recent CT scan, with a recommended instilled volume of at least 100 mL, as suggested by the Infectious Diseases Society of America in 2016 1. The diagnostic yield of BAL also varies by the type of radiographic lesion, with consolidations and tree-in-bud–type abnormalities having a higher yield, as reported in the practice guidelines for the diagnosis and management of aspergillosis in 2016 1.
From the Research
BAL Findings in Fungal Infections
The following are the BAL findings in fungal infections:
- The presence of Aspergillus hyphae in BAL samples has a 53% sensitivity, 97% specificity, and 75% positive predictive value for the diagnosis of invasive pulmonary aspergillosis 2
- BAL galactomannan (GM) has a sensitivity of 0.84 (95% CI, 0.73-0.91) and specificity of 0.88 (95% CI, 0.81-0.91) in patients with impaired immunity suspected of having invasive aspergillosis 3
- BAL PCR in patients at high risk for invasive aspergillosis has a high sensitivity of 0.90 (95% CI, 0.77-0.96) and specificity of 0.96 (95% CI, 0.93-0.98) for diagnosing invasive aspergillosis 3
- The sensitivity, specificity, and positive and negative predictive values of BAL (+ fungi) were 85.1% (63/74), 81.4% (140/172), 66.3% (63/95), and 92.7% (140/151), respectively, in non-neutropenic intensive-care unit patients with suspected tracheobronchial fungal infection 4
- Galactomannan in BAL provided 50% sensitivity, 73.0% specificity, 16% positive predictive value, and 93% negative predictive value for diagnosing proven+probable invasive fungal disease in hematologic malignancies 5
Diagnostic Utility of BAL
The diagnostic utility of BAL in fungal infections is as follows:
- BAL is a valuable first procedure for diagnosing invasive pulmonary aspergillosis in the compromised host 2
- Observing sticky secretions, hyperaemic mucosa, and whitish plaques by bronchoscopy is faster than and may be as reliable as microbiology for diagnosing tracheobronchial fungal infection 4
- BAL and biopsy in children with an oncological diagnosis or those undergoing HSCT only infrequently lead to changes in management in the era of empiric therapy with broad-spectrum anti-fungal agents 6
- GM in BAL had modest agreement with EORTC/MSG criteria for diagnosing invasive fungal disease in immunocompromised patients with a high degree of antifungal exposure 5