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

Abstract

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.

Comparison of molecular and MALDI-TOF MS identification and antifungal susceptibility of clinical Fusarium isolates in Southern China

“…Our results demonstrated FSSC (70.5%, 67/95) was the most prevalent group mainly originating from corneal scrapings (33/45), followed by FFSC (16.8%, 16/95) and FOSC (7.4%, 7/95). The prevalence of Fusarium SC here showed similar as Song's finding in Northern China and Sun's finding in central China (Sun et al, 2015;Song et al, 2021). There were 40.0% (38/95) of isolates in this study that were obtained from skin secretions, a proportion of which were collected from inpatients with burns or diabetes mellitus (data not shown).…”

“…We observed that MALDI-TOF MS had excellent performance of Fusarium identification at the SC level with the correct rate up to 91.6% (87/95), taking DNA sequencing of TEF1α as the gold standard ( Herkert et al, 2019 ; Oliveira et al, 2020 ; Da et al, 2021 ). Similar results were achieved by Paziani et al (94.4%) and Song et al (95.2%; Paziani et al, 2019 ; Song et al, 2021 ). To a large extent, it attributed to a success ratio of 100% correct identifications for the most prevalent SC (FSSC; Table 1 ).…”

“…The clinically relevant Fusarium species are mainly grouped into six species complexes (SC), including the F. solani SC (FSSC), F. oxysporum SC (FOSC), F. fujikuroi SC (FFSC), F. dimerum SC (FDSC), F. incarnatum-equiseti SC (FIESC), and F. chlamydosporum SC (FCSC; Triest et al, 2015 ). It has been found that antifungal susceptibility may vary among different species within a single species complex ( O’Donnell et al, 2008 ; Al-Hatmi et al, 2015b ; Song et al, 2021 ), which indicates it is necessary to identify the aetiological agent up to the species level for clinical treatment. In the clinical laboratory, these closely related species are often morphologically indistinguishable.…”

“…However, it has been reported that clinical Fusaria have relatively decreased susceptibility to these commonly used antifungal drugs ( Taj-Aldeen et al, 2016 ; Rosa et al, 2019 ). Different patterns of in vitro susceptibility have been found in different Fusarium species ( Song et al, 2021 ). Remarkably, since neither clinical breakpoints nor epidemiological cutoff values have been established for Fusarium according to Clinical and Laboratory Standards Institute (CLSI) M59-3ed ( CLSI, 2020 ) and EUCAST database, 1 information on the correlation between minimum inhibitory concentration (MIC) and drug efficacy is not clear.…”

A review of the potential of lichen substances as antifungal agents: the effects of extracts and lichen secondary metabolites on Fusarium fungi

“…Increased resistance of fungal complexes of F. fujikuroi , F. oxysporum and F. solani species may cause human disorders (see: Batista et al 2020 ; Dignani and Anaissie 2004 ; Herkert et al 2019 ; Nelson et al 1994 ; Song et al 2021 ), most commonly onychomycosis, skin infections and keratitis (see: Batista et al 2020 and literature cited therein; Herkert et al 2019 ); they also contribute to systemic conditions, including disorders of the nervous system (see: Dignani and Anaissie 2004 ), the heart (endocarditis: Esnakula et al 2013 ), and tissues, such as the skin, lungs and sinuses (Dignani and Anaissie 2004 ). Their presence may be the cause of the so-called sick-building syndrome (Li and Yang 2004 ; Chróst 2016 ; Nag 2019 ), and together with the mycotoxins produced by Fusarium (Dignani and Anaissie 2004 ), can negatively affect the quality of food products and the health of humans (Köycü 2018 ; Nelson et al 1994 ).…”