Molecular diagnostics in fungal infections

Abstract

Invasive fungal disease (IFD) causes significant morbidity and mortality in hospitalised patients, despite advances in antifungal therapies. Rapid, accurate diagnostic tests are essential for improving patient outcomes. Molecular diagnostic methods, including both broad-range and specific PCR assays, and proteomic approaches such as matrix-assisted laser desorption ionisation-time of flight mass spectroscopy (MALDI-TOF MS) have great potential to enhance sensitivity and speed to diagnosis of IFD, but have varying specificities. These assays are mainly used to complement conventional methods as they lack clinical validation and require standardisation before they can be recommended for widespread implementation. To date no molecular based assays have been incorporated into diagnostic criteria for defining IFD, however the development of commercial assays is likely to assist standardisation. The emergence of antifungal drug resistance in Candida spp. and Aspergillus spp. is concerning. Molecular methods, including PCR and next generation sequencing, have been developed for the detection of azole and echinocandin resistance in Candida species and azole resistance in Aspergillus species. These tests are not widely available to diagnostic laboratories, but are likely to be key for epidemiological surveillance of antifungal resistance in coming years.