Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user’s needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option available.
Members of the genus Curvularia are melanin-producing dematiaceous fungi of increasing clinical importance as causal agents of both local and invasive infections. This study contributes to the taxonomical and clinical knowledge of this genus by describing two new Curvularia species based on isolates from corneal scrapings of South Indian fungal keratitis patients. The phylogeny of the genus was updated based on three phylogenetic markers: the internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster as well as fragments of the glyceraldehyde-3-phosphate dehydrogenase (gpdh) and translation elongation factor 1-α (tef1α) genes. The maximum likelihood phylogenetic tree constructed from the alignment of the three concatenated loci revealed that the examined isolates are representing two new, yet undescribed, Curvularia species. Examination of colony and microscopic morphology revealed differences between the two species as well as between the new species and their close relatives. The new species were formally described as Curvularia tamilnaduensis N. Kiss & S. Kocsubé sp. nov. and Curvularia coimbatorensis N. Kiss & S. Kocsubé sp. nov. Antifungal susceptibility testing by the broth microdilution method of CLSI (Clinical & Laboratory Standards Institute) revealed that the type strain of C. coimbatorensis is less susceptible to a series of antifungals than the C. tamilnaduensis strains.
14 April 2017 in Annals of Clinical Microbiology and Antimicrobials
Scedosporium apiospermum is an emerging opportunistic filamentous fungus, which is notorious for its high levels of antifungal-resistance. It is able to cause localized cutaneous or subcutaneous infections in both immunocompromised and immunocompetent persons, pulmonary infections in patients with predisposing pulmonary diseases and invasive mycoses in immunocompromised patients. Subcutaneous infections caused by this fungus frequently show chronic mycetomatous manifestation. We report the case of a 70-year-old immunocompromised man, who developed a fungal mycetomatous infection on his right leg. There was no history of trauma; the aetiological agent was identified by microscopic examination and ITS sequencing. This is the second reported case of S. apiospermum subcutaneous infections in Hungary, which was successfully treated by surgical excision and terbinafine treatment. After 7 months, the patient remained asymptomatic. Considering the antifungal susceptibility and increasing incidence of the fungus, Scedosporium related subcutaneous infections reported in the past quarter of century in European countries were also reviewed. Corticosteroid treatment represents a serious risk factor of S. apiospermum infections, especially if the patient get in touch with manure-enriched or polluted soil or water. Such infections have emerged several times in European countries in the past decades. The presented data suggest that besides the commonly applied voriconazole, terbinafine may be an alternative for the therapy of mycetomatous Scedosporium infections.
The present study was carried out to investigate the antifungal effects of Cinnamomum zeylanicum, Citrus limon, Juniperus communis, Eucalyptus citriodora, Gaultheria procumbens, Melaleuca alternifolia, Origanum majorana, Salvia sclarea, and Thymus vulgaris essential oils against Fusarium species, the most common etiologic agents of filamentous fungal keratitis in South India. C. zeylanicum essential oil showed strong anti-Fusarium activity, whereas all the other tested essential oils proved to be less effective. The main component of C. zeylanicum essential oil, trans-cinnamaldehyde, was also tested and showed a similar effect as the oil. The in vitro interaction between trans-cinnamaldehyde and natamycin, the first-line therapeutic agent of Fusarium keratitis, was also investigated; an enhanced fungal growth inhibition was observed when these agents were applied in combination. Light and fluorescent microscopic observations revealed that C. zeylanicum essential oil/trans-cinnamaldehyde reduces the cellular metabolism and inhibits the conidia germination. Furthermore, necrotic events were significantly more frequent in the presence of these two compounds. According to our results, C. zeylanicum essential oil/trans-cinnamaldehyde provides a promising basis to develop a novel strategy for the treatment of Fusarium keratitis.
Members of the Scedosporium apiospermum species complex are the second most frequently isolated pathogens after Aspergillus fumigatus from cystic fibrosis (CF) patients with fungal pulmonary infections. Even so, the main risk factors for the infection are unrevealed. According to previous studies, bacterial infections might reduce the risk of a fungal infection, but an antibacterial therapy may contribute to the airway colonization by several fungal pathogens. Furthermore, corticosteroids, which are often used to reduce lung inflammation in children and adults with CF, are also proved to enhance the growth of A. fumigatus in vitro. Considering all the above discussed points, we aimed to test how Pseudomonas aeruginosa influences the growth of scedosporia and to investigate the potential effect of commonly applied antibacterial agents and corticosteroids on Scedosporium species. Direct interactions between fungal and bacterial strains were tested using the disk inhibition method. Indirect interactions via volatile compounds were investigated by the plate-in-plate method, while the effect of bacterial media-soluble molecules was tested using a modified cellophane assay and also in liquid culture media conditioned by P. aeruginosa. To test the effect of bacterial signal molecules, antibacterial agents and corticosteroids on the fungal growth, the broth microdilution method was used. We also investigated the germination ability of Scedosporium conidia in the presence of pyocyanin and diffusible signal factor by microscopy. According to our results, P. aeruginosa either inhibited or enhanced the growth of scedosporia depending on the culture conditions and the mode of interactions. When the two pathogens were cultured physically separately from each other in the plate-in-plate tests, the presence of the bacteria was able to stimulate the growth of several fungal isolates. While in direct physical contact, bacterial strains inhibited the fungal growth. This effect might be attributed to bacterial signal molecules, which also proved to inhibit the germination and growth of scedosporia. In addition, antibacterial agents showed growth-promoting, while corticosteroids exhibited growth inhibitory effect on several Scedosporium isolates. These data raise the possibility that a P. aeruginosa infection or a previously administered antibacterial therapy might be able to increase the chance of a Scedosporium colonization in a CF lung.
Mucor lusitanicus and some other members of the fungal order Mucorales display the phenomenon of morphological dimorphism. This means that these fungi aerobically produce filamentous hyphae, developing a coenocytic mycelium, but they grow in a multipolar yeast-like form under anaerobiosis. Revealing the molecular mechanism of the reversible yeast-hyphal transition can be interesting for both the biotechnological application and in the understanding of the pathomechanism of mucormycosis. In the present study, transcriptomic analyses were carried out after cultivating the fungus either aerobically or anaerobically revealing significant changes in gene expression under the two conditions. In total, 539 differentially expressed genes (FDR < 0.05, |log2FC| ≥ 3) were identified, including 190 upregulated and 349 downregulated transcripts. Within the metabolism-related genes, carbohydrate metabolism was proven to be especially affected. Anaerobiosis also affected the transcription of transporters: among the 14 up- and 42 downregulated transporters, several putative sugar transporters were detected. Moreover, a considerable number of transcripts related to amino acid transport and metabolism, lipid transport and metabolism, and energy production and conversion were proven to be downregulated when the culture had been transferred into an anaerobic atmosphere.