Aspergillus Galactofuranose Antigen by EIA, Urine

Invasive aspergillosis (IA) is an opportunistic infection caused by Aspergillus species. Individuals with weakened immune systems are most at risk for developing IA. ^,  Detection of Aspergillus galactomannan, a fungal cell wall polysaccharide, in serum or bronchoalveolar lavage fluid, is commonly used as an aid in the diagnosis of IA. Galactofuranose is an additional antigen that can be detected in the urine of individuals with IA.  Galactofuranose urine testing may be used as an aid in the diagnosis of IA when clinically suspected in individuals with immunosuppression, or as a screening tool in high-risk populations, such as those with prolonged neutropenia. ^, 

Test Interpretation

This is a qualitative test; concentrations of galactofuranose are reported as an enzyme immunoassay (EIA) index. Results should be interpreted in the context of patient history, clinical signs/symptoms, and other routine diagnostic tests (histopathologic, radiographic, and culture examination).  There is a risk of false-positive results in the presence of other ascomycetes fungi. Cross-reactivity has been observed with Histoplasma, Blastomyces, and Fusarium. False-positive results may also occur in the presence of certain interfering substances, including high concentrations of topical antifungal creams (e.g., butenafine, clotrimazole, miconazole, and tioconazole), benzocaine cream, or vaginal contraceptive gel; elevated bilirubin and hemoglobin concentrations; or high concentrations of the dietary compounds betanin and caffeine.

Clinical Sensitivity and Specificity

According to the manufacturer, the clinical sensitivity and specificity of this assay for IA are 90.5% and 89.2%, respectively. 

Analytic Sensitivity

The limit of detection (LOD) for this test is 3 ng/mL. 

Results

Limitations

This test has not been validated for use in pediatric patient populations, individuals who have received previous antifungal therapy, or lung transplant recipients.