What is Fungitell (a diagnostic test) specific for?

Fungitell Specificity for Fungal Infections

Fungitell is a diagnostic test that detects (1,3)-β-D-glucan, a cell wall component present in multiple fungal species, but is not specific for any single fungal pathogen. 1

Fungal Pathogens Detected by Fungitell

Fungitell can detect the presence of:

• Candida species
• Aspergillus species
• Pneumocystis jirovecii
• Fusarium species
• Acremonium species

However, Fungitell notably does not detect:

• Mucorales (causative agents of mucormycosis) due to lack of significant (1,3)-β-D-glucan in their cell walls
• Cryptococcus species (have low levels of (1,3)-β-D-glucan)

Diagnostic Performance

The Fungitell assay demonstrates:

• Sensitivity of approximately 75-80% for invasive candidiasis 1
• Specificity of approximately 80% for invasive fungal infections 1
• High negative predictive value (>85%), making it more useful for excluding fungal infection than confirming it 1, 2

Clinical Applications

Fungitell is FDA-approved as an adjunct to cultures for diagnosing invasive fungal infections, not as a standalone diagnostic test 1. Its primary utility includes:

1. Early detection: Can identify invasive candidiasis days to weeks before positive blood cultures 1
2. Monitoring response: Decreasing β-D-glucan levels may correlate with response to antifungal therapy 1
3. Screening: May be used in high-risk patients, particularly when combined with other diagnostic methods 1

Limitations and False Positives

False positive results can occur with:

• Hemodialysis
• Administration of albumin or immunoglobulins
• Certain antibiotics (particularly some β-lactams like piperacillin-tazobactam)
• Blood product transfusions
• Use of glucan-contaminated blood collection tubes or gauze
• Bacterial infections (particularly gram-positive bacteremia) 1, 2

Diagnostic Strategy

For optimal diagnostic value:

• Serial testing (twice weekly) is recommended rather than a single measurement 1
• Combine with other diagnostic methods such as cultures, imaging, and other biomarkers
• Consider as part of a comprehensive diagnostic approach rather than relying solely on Fungitell results 2

Clinical Recommendation

The Fungitell assay should be used as part of a comprehensive diagnostic strategy for invasive fungal infections, with recognition that a negative result has greater utility for excluding infection than a positive result has for confirming it. 1, 2

When interpreting results, clinicians should consider the patient's risk factors, clinical presentation, and results of other diagnostic tests, while being aware of potential causes of false positive results.