Tissue Diagnosis of Invasive Fungal Infections: Current Limitations and the Emerging Use of Molecular Techniques

Abstract

Invasive fungal diseases (IFD) due to opportunistic fungi are commonly treated using empirical antifungal therapy. Therefore, a comprehensive study of organisms associated with IFD is essential to define successful empiric therapies in each setting. Current diagnostic tests, such as culture, histology and serology are suboptimal, leading to delays in the initiation of antifungal therapies and resulting in high mortality rates despite the availability of several new antifungal agents. Using molecular methods to identify fungal pathogens directly from formalin-fixed, paraffin-embedded tissues is emerging as a diagnostic approach. The goal of this molecular approach is to complement conventional diagnostic tests through the reliable detection and identification of fungal nucleic acids or antigens in tissues so as to direct antiinfective therapies and improve patient outcomes. Here we review challenges and recent advances in the identification of fungal pathogens from tissue samples by conventional and molecular methods.