Biomarkers in Invasive Pulmonary Fungal Infections: Where Do We Stand?

Invasive pulmonary fungal infections remain a major cause of morbidity and mortality among immunocompromised and critically ill patients. Rapid and accurate diagnosis is crucial for improving outcomes, yet conventional methods such as culture and histopathology suffer from limited sensitivity and slow turnaround times. Recently, significant progress has been made in the development and standardization of serological and molecular biomarkers that enhance the early detection of the key pulmonary fungal diseases, particularly invasive pulmonary aspergillosis and pneumocystosis. Diagnostic tools for mucormycosis, however, remain scarce. PCR tools have strong potential to significantly improve early detection, but they are not yet widely implemented, and standardized commercial assays remain limited. Accessible antigen-based tests with robust performance are highly anticipated and expected to become available soon. This review summarizes the current evidence regarding the optimal use of galactomannan, β-D-glucan and PCR-based assays, emphasizing how their performance varies according to the pathogen, the type of specimen and the host population. Specific challenges, such as differentiating colonization from infection in non-HIV Pneumocystis pneumonia or interpreting galactomannan and PCR in patients receiving mold-active prophylaxis, are highlighted. We also discuss how combining biomarkers can enhance diagnostic accuracy and support timely therapeutic decisions. A clear understanding of the strengths, limitations and appropriate interpretation of these diagnostic tools is crucial in an era of increasing host complexity, shifting fungal epidemiology, and expanding antifungal options.