Can Clavispora lusitaniae Cause Elevated Fungitell Results?
Yes, Clavispora lusitaniae (formerly Candida lusitaniae) infection will cause elevated serum (1→3)-β-D-glucan (Fungitell) results, as this organism contains β-D-glucan in its cell wall like other Candida species.
Mechanism and Expected Results
β-D-glucan is a cell wall component of most pathogenic fungi, including all Candida species, and the Fungitell assay detects this polysaccharide when invasive fungal infection is present 1.
C. lusitaniae, being a Candida species, possesses (1→3)-β-D-glucan in its cell wall structure, making it detectable by the Fungitell assay just like C. albicans, C. glabrata, C. parapsilosis, and other Candida species 1.
In documented candidemia cases (including all Candida species), all culture-proven samples showed BDG values >80 pg/ml (mean 1247 pg/ml; range 116-2990 pg/ml) using the automated Fungitell assay 2.
Clinical Context for C. lusitaniae
C. lusitaniae is an emerging opportunistic pathogen that causes breakthrough fungemia in immunocompromised patients, particularly those with hematologic malignancies, bone marrow transplant recipients, and neutropenic patients 3.
This organism has characteristic resistance patterns, including documented amphotericin B resistance and rapid development of multidrug resistance during echinocandin therapy 4, 3.
C. lusitaniae can be confused with other fungal species such as C. tropicalis, C. parapsilosis, and even Saccharomyces cerevisiae due to morphologic similarities, making biomarker testing particularly valuable 5.
Diagnostic Performance Considerations
The Fungitell assay has a pooled sensitivity of 75-80% and specificity of approximately 80% for invasive fungal infections, with results available within 45 minutes to 24 hours 1, 6, 2.
The test cannot distinguish between different fungal species - a positive result indicates invasive fungal infection but does not differentiate C. lusitaniae from other Candida species, Aspergillus, Fusarium, or Pneumocystis jirovecii 7, 8.
Blood culture sensitivity for candidemia ranges from only 21-71%, so negative cultures do not rule out infection, making BDG testing a valuable adjunct 6.
Important Caveats
False-positive BDG results are common in ICU patients, those receiving hemodialysis, albumin or IVIG infusions, certain antibiotics (particularly amoxicillin-clavulanate, piperacillin-tazobactam), and those with mucositis or gastrointestinal mucosal disruption 1, 6, 8.
Requiring consecutive positive results rather than a single positive test improves specificity and reduces false-positive interpretation 1, 8.
A positive Fungitell result should prompt blood cultures, site-specific cultures, and consideration of empiric antifungal therapy in high-risk patients with clinical signs of infection 6.