From the Research
A cerebrospinal fluid (CSF) Aspergillus galactomannan antigen index value of ≥0.7 is generally considered positive for central nervous system aspergillosis, as indicated by the most recent study 1. This cutoff represents a threshold used in clinical practice for diagnosing central nervous system aspergillosis. The test detects galactomannan, a polysaccharide component of the Aspergillus cell wall that is released during fungal growth. Some key points to consider when interpreting CSF galactomannan results include:
- The sensitivity and specificity of CSF galactomannan vary depending on the patient population and whether antifungal therapy has been initiated prior to testing, as noted in studies such as 2 and 1.
- False positives can occur with cross-reacting antigens from other fungi or certain antibiotics like piperacillin-tazobactam.
- False negatives may result from low fungal burden or prior antifungal therapy.
- Clinicians should consider the test in conjunction with clinical presentation, imaging findings, and other microbiological data, as suggested by studies including 3, 4, and 5. The most recent and highest quality study, 1, provides the best evidence for the cutoff value of ≥0.7, which is used to determine the presence of central nervous system aspergillosis.