Molecular and MALDI-ToF MS differentiation and antifungal susceptibility of prevalent clinical Fusarium species in China

Background Fusarium species are emerging causative agents of superficial and disseminated human infections. Early diagnosis and treatment contribute to better prognosis of severe infection. Objectives To detect the effectiveness of matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF MS) for Fusarium identification, and evaluate the susceptibility profiles to clinical available antifungals. Methods All 203 clinical Fusarium isolates and 25 environmental isolates were identified by using translation elongation factor 1-alpha (TEF1) and RNA polymerase subunit II (RPB2) sequencing and MALDI-ToF MS. Antifungal susceptibility testing was determined by a microdilution method following the CLSI approved standard M38-A3 document. Results Correct identification rates at the species and genus levels were 89.04% (203/228) and 95.18% (217/228), respectively, using Bruker Filamentous Fungi Library 1.0 combined with the novel database. Seven species complexes with 19 Fusarium species were identified, including F. solani (59.21%, n = 135), F. verticillioides (17.54%, n = 40), F. proliferatum (6.58%, n = 15) and F. oxysporum (4.39%, n = 10). Four uncommon species complexes (F. incarnatum-equiseti SC, F. dimerum SC, F. redolens SC and F. sporotrichioides SC) were also identified. A high degree of antifungal resistance was observed. Fusarium isolates exhibited lower MICs to luliconazole and terbinafine compared with amphotericin B and voriconazole, which in turn were significantly more active than amorolfine, fluconazole and itraconazole. Conclusions MALDI-ToF MS showed good performance in Fusarium species with an adapted Bruker library and expanded database. Fusarium isolates exhibited lower MICs to luliconazole and terbinafine compared to amphotericin B and voriconazole.