Clinical Utility and Diagnostic Performance of (1→3)-β-D-Glucan in Invasive Mycoses

The BDG assay is a non-culture-based biomarker widely used in the diagnosis of invasive fungal infections, particularly among immunocompromised patients. Conventional diagnostic methods, including culture and histopathology, are limited by low sensitivity and delayed turnaround times, prompting increased reliance on adjunctive serologic markers.

BDG, a conserved component of the fungal cell wall, is detectable in serum across multiple clinically relevant fungi, including Candida spp., Aspergillus spp., and Pneumocystis jirovecii, but is absent or minimally expressed in organisms such as Blastomyces spp., Cryptococcus spp., and Mucorales. Multiple commercial BDG assays are available globally and differ in methodology, performance characteristics, and geographic availability, contributing to interassay variability and challenges in interpretation. Diagnostic performance also varies by pathogen and host population.

Optimal use of BDG requires integration into a structured diagnostic framework incorporating host risk factors, imaging, microbiology, and complementary fungal biomarkers. Diagnostic stewardship is essential, as testing in low pretest probability settings reduces positive predictive value and may lead to inappropriate antifungal use. Emerging simplified assay formats and improved diagnostic algorithms may enhance turnaround time and clinical applicability.

Overall, BDG is a valuable but imperfect adjunctive biomarker whose most promising utility lies in supporting clinical decision-making and antifungal stewardship in appropriately selected high-risk populations.