Mucormycosis is known to be a rare opportunistic infection caused by Syncephalastrum species, which are Mucorales fungi of the Zygomycetes class. These moulds are rarely involved in clinical diseases and are generally seen as contaminants in the clinical laboratory. However, in recent years, case reports of human infections due to Syncephalastrum have increased, especially in immunocompromised hosts. In this study, we describe two new Syncephalastrum species, which were isolated from human nails and sputum samples from two different patients.
We used several methods of genomic and phenotypic characterisation. The phenotypic analysis, relied on morphological features, analysed both by optical and scanning electron microscopy. We used Matrix Assisted Laser Desorption Ionization-Time of Flight mass spectrometry, energy-dispersive X-ray spectroscopy, and BiologTM technology to characterise the proteomic, chemical mapping, and carbon source assimilation profiles, respectively. The genomic analysis relied on multilocus sequence analysis of the rRNA internal transcribed spacers and D1/D2 large-subunit domains, and fragments of the translation elongation factor 1-alpha, and the β-tubulin genes.
The two novel species in the genus Syncephalastrum, namely S. massiliense PMMF0073 and S. timoneanum PMMF0107, have a similar morphology to S. racemosum, but each display distinct phenotypic and genotypic features. The polyphasic approach, combining the results of complementary phenotypic and genomic assays, was instrumental in describing and characterising these two new Syncephalastrum species.