Scytalidium dimidiatum associated invasive fungal sinusitis in an immunocompetent patient

Genotyping and In Vitro Antifungal Susceptibility Profile of Neoscytalidium Species Isolates from Respiratory Tract

The fungus genus Neoscytalidium is mainly distributed in (sub) tropical regions of the world and has been essentially considered as a phytopathogen. There are however several reports of human infection caused by Neoscytalidium spp. through direct or indirect contact with contaminated plants or soil. Reliable and accurate identification to species level is critical for implementing proper therapeutic strategies. In the present study we investigated the genotypes and in vitro antifungal susceptibility patterns of Neoscytalidium species identified from respiratory tracts of patients with various underlying diseases. The identity and diversity of the isolates were done using PCR and sequencing of five different loci (the ITS region, D1/D2 domains of 28S rRNA gene, and part of the beta tubulin, elongation factor 1α and chitin synthase genes). The in-vitro antifungal susceptibility was also performed using the Clinical and Laboratory Standards Institute (CLSI) M38-Ed3-2017 guidelines. Overall, 13 isolates were identified as Neoscytalidium species (eight N. dimidiatum and five N. novaehollandiae). Two sequence types (STs) were identified by the alignment of 1846 combined base pairs among 13 clinical isolates. All isolates classified as N. dimidiatum were clustered in ST6 (61.5%) and those of N. novaehollandiae were in ST7 (38.5%). Luliconazole was the most active antifungal in vitro against species. This is the first report of N. novaehollandiae isolation from respiratory tracts samples. Further study from other regions of the world with a larger set of clinical specimens is required to provide additional insight into diversity of Neoscytalidium species.