Aspergillus Galactomannan Antigen

A positive Aspergillus galactomannan antigen test means galactomannan — a cell‑wall component of Aspergillus — was detected, raising suspicion for invasive aspergillosis, especially in immunocompromised people. The test isn’t definitive: sensitivity varies and false positives can occur (e.g., certain antibiotics or cross-reacting organisms). Clinical context, imaging, and additional tests (culture, PCR, repeat antigen) are needed to confirm diagnosis.

Aspergillus antigen is usually reported as a galactomannan optical density index. A normal (negative) result is generally an index below 0.5 in serum. Bronchoalveolar lavage thresholds vary—many labs use <0.5 as negative, while cutoffs of 0.5–1.0 or ≥1.0 may define positivity. Measured by enzyme immunoassay, values are reported as index values and must be correlated clinically.

Patients at high risk of invasive aspergillosis should get galactomannan testing: immunocompromised individuals — prolonged neutropenia, hematologic malignancies, bone marrow or solid-organ transplant recipients, and those on high-dose corticosteroids or other immunosuppressants. Also consider testing in ICU patients with persistent fever or new respiratory symptoms unresponsive to antibiotics. Serum and bronchoalveolar lavage samples help diagnose and monitor therapy.

The Aspergillus galactomannan test is an enzyme immunoassay that detects galactomannan antigen in serum, bronchoalveolar lavage (BAL) fluid, or cerebrospinal fluid to help diagnose invasive aspergillosis. Results are reported as an optical density index; common positivity cut-offs are ≥0.5 in serum and ≥1.0 in BAL. It can yield false positives with some antibiotics and foods, so repeat testing and clinical correlation are recommended.

Aspergillus infections are often treatable but whether they are curable depends on the form and the person’s immune status. Allergic or superficial disease is usually manageable; chronic pulmonary forms commonly require long-term antifungal therapy and sometimes surgery. Invasive aspergillosis is serious and can be life‑threatening but may be cured with prompt, aggressive antifungal treatment.

No — Aspergillus is a genus of mold (a fungus), not tuberculosis. TB is caused by the bacterium Mycobacterium tuberculosis. Aspergillus can infect the lungs (aspergillosis), sometimes mimicking TB or colonizing old TB cavities (aspergilloma), but diagnosis and treatment differ: antifungal therapy for Aspergillus versus antibiotics for TB. Proper testing distinguishes them.