Correlation of Trichosporon asahii Genotypes with Anatomical Sites and Antifungal Susceptibility Profiles: Data Analyses from 284 Isolates Collected in the Last 22 Years across 24 Medical Centers

Unveiling Trichosporon austroamericanum sp. nov.: A Novel Emerging Opportunistic Basidiomycetous Yeast Species

During an epidemiological survey, a potential novel species within the basidiomycetous yeast genus Trichosporon was observed. The clinical strain was obtained from a urine sample taken from a Brazilian kidney transplant recipient. The strain was molecularly identified using the intergenic spacer (IGS1) ribosomal DNA locus and a subsequent phylogenetic analysis showed that multiple strains that were previously reported by other studies shared an identical IGS1-genotype most closely related to that of Trichosporon inkin. However, none of these studies provided an in-depth characterization of the involved strains to describe it as a new taxon. Here, we present the novel clinically relevant yeast for which we propose the name Trichosporon austroamericanum sp. nov. (holotype CBS H-24937). T. austroamericanum can be distinguished from other siblings in the genus Trichosporon using morphological, physiological, and phylogenetic characters.

The Potential Use of Peptides in the Fight against Chagas Disease and Leishmaniasis

Chagas disease and leishmaniasis are both neglected tropical diseases that affect millions of people around the world. Leishmaniasis is currently the second most widespread vector-borne parasitic disease after malaria. The World Health Organization records approximately 0.7-1 million newly diagnosed leishmaniasis cases each year, resulting in approximately 20,000-30,000 deaths. Also, 25 million people worldwide are at risk of Chagas disease and an estimated 6 million people are infected with Trypanosoma cruzi. Pentavalent antimonials, amphotericin B, miltefosine, paromomycin, and pentamidine are currently used to treat leishmaniasis. Also, nifurtimox and benznidazole are two drugs currently used to treat Chagas disease. These drugs are associated with toxicity problems such as nephrotoxicity and cardiotoxicity, in addition to resistance problems. As a result, the discovery of novel therapeutic agents has emerged as a top priority and a promising alternative. Overall, there is a need for new and effective treatments for Chagas disease and leishmaniasis, as the current drugs have significant limitations. Peptide-based drugs are attractive due to their high selectiveness, effectiveness, low toxicity, and ease of production. This paper reviews the potential use of peptides in the treatment of Chagas disease and leishmaniasis. Several studies have demonstrated that peptides are effective against Chagas disease and leishmaniasis, suggesting their use in drug therapy for these diseases. Overall, peptides have the potential to be effective therapeutic agents against Chagas disease and leishmaniasis, but more research is needed to fully investigate their potential.

Genome-Wide Identification and Characterization of the Medium-Chain Dehydrogenase/Reductase Superfamily of Trichosporon asahii and Its Involvement in the Regulation of Fluconazole Resistance

The medium-chain dehydrogenase/reductase (MDR) superfamily contains many members that are widely present in organisms and play important roles in growth, metabolism, and stress resistance but have not been studied in Trichosporon asahii. In this study, bioinformatics and RNA sequencing methods were used to analyze the MDR superfamily of T. asahii and its regulatory effect on fluconazole resistance. A phylogenetic tree was constructed using Saccharomyces cerevisiae, Candida albicans, Cryptococcus neoformans, and T. asahii, and 73 MDRs were identified, all of which contained NADPH-binding motifs. T. asahii contained 20 MDRs that were unevenly distributed across six chromosomes. T. asahii MDRs (TaMDRs) had similar 3D structures but varied greatly in their genetic evolution at different phylum levels. RNA-seq and gene expression analyses revealed that the fluconazole-resistant T. asahii strain upregulates xylitol dehydrogenase, and downregulated alcohol dehydrogenase and sorbitol dehydrogenase concluded that the fluconazole-resistant T. asahii strain was less selective toward carbon sources and had higher adaptability to the environment. Overall, our study contributes to our understanding of TaMDRs, providing a basis for further analysis of the genes associated with drug resistance in T. asahii.

In vitro activity of isavuconazole against clinically relevant Trichosporon species: a comparative evaluation of EUCAST broth microdilution and MIC Test Strip methods

OBJECTIVES

To evaluate the in vitro activity of isavuconazole on 154 clinical and reference strains of Trichosporon asahii, Trichosporon asteroides, Trichosporon coremiiforme, Trichosporon faecale and Trichosporon inkin by using the EUCAST broth microdilution method (BMD) and Liofilchem MIC Test Strips (MTS).

METHODS

Antifungal susceptibility testing for isavuconazole, fluconazole, voriconazole and posaconazole was assessed by EUCAST E.DEF 7.3.2. MIC values of isavuconazole obtained by BMD after 48 h of incubation were compared with MTS MICs after 24 and 48 h of incubation.

RESULTS

T. asahii and T. asteroides showed the highest isavuconazole MIC90 values (0.5 mg/L). In clinical isolates, T. asahii exhibited the highest MIC90 values (0.5 mg/L) compared with non-T. asahii (0.06-0.25 mg/L). The five non-WT T. asahii isolates for fluconazole, voriconazole and posaconazole also exhibited high MICs of isavuconazole (≥0.5 mg/L). A better correlation between MTS and BMD MICs was observed after 24 h incubation for all species tested. MTS measurements performed at 48 h increased by at least 122% the number of isolates with >2 dilutions compared with the standard method.

CONCLUSIONS

Isavuconazole exhibited variable in vitro activity among the Trichosporon species tested, showing higher or equal MICs than the other azoles. The five non-WT T. asahii clinical isolates tested also exhibited high isavuconazole MICs, suggesting the occurrence of triazole cross-resistance. Our MTS data indicate that there is no advantage in extended reading time for MTS from 24 to 48 h for Trichosporon yeasts.

JMM Profile: Trichosporon yeasts: from superficial pathogen to threat for haematological-neutropenic patients

Trichosporon yeasts are classical agents of superficial mycoses, and they are ranked as the first to second predominant basidiomycetous yeast able to cause invasive infections. The clinical presentation of Trichosporon infections varies with the affected anatomical site, with fungaemia present in the majority of invasive trichosporonosis cases. Only a limited number of antifungal compounds can be used to treat Trichosporon infections. Azoles are the first choice due to their intrinsic resistance to echinocandins. Better laboratory methods and up-to-date databases of commercial platforms are required to improve identification, susceptibility testing and surveillance of this potentially threating infection.

Genotyping, antifungal susceptibility testing, and biofilm formation of Trichosporon spp. isolated from urine samples in a University Hospital in Bangkok, Thailand

The basidiomycetes yeast Trichosporon is widespread in the natural environment, but can cause disease, mainly in immunocompromised patients. However, there have been only few studies about this infection in Thailand. In this study, we characterized 53 Trichosporon spp. isolated from urine samples from patients admitted to a single hospital in Bangkok, Thailand over a one-year period from 2019 to 2020. The strains were identified using colony morphology, microscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and nucleotide sequence analysis of intergenic spacer 1 (IGS1). Fifty-one isolates were Trichosporon asahii, and the remaining isolates were Trichosporon inkin and other Trichosporon species. Three genotypes of IGS1-1, 3, and 7 were observed among T. asahii. The sensitivity of the yeasts to the antifungal drugs amphotericin B, fluconazole, and voriconazole ranged from 0.25 to >16 μg ml-1, 0.5-8 μg ml-1, and 0.01-0.25 μg ml-1, respectively. We investigated biofilm formation by the isolates, and no biofilm production was found in one isolate, low biofilm production in forty-four isolates, and medium biofilm production in six isolates. T. inkin produced biofilms at low levels, and Trichosporon spp. produced biofilms at medium levels. This research increases our understanding of the molecular epidemiology of Trichosporon spp. isolated from one university hospital in Bangkok, Thailand, and reveals their genetic diversity, antifungal susceptibility profiles, and capacity for in vitro biofilm production.

Short sequence repeats of the intergenic spacer regions of ribosomal RNA genes in Malassezia globosa and M. restricta colonizing the scalps of male individuals with and without androgenetic alopecia

We analyzed the short sequence repeats (SSRs) of the intergenic spacer (IGS) region 1 of the rRNA genes in Malassezia globosa and M. restricta, which predominantly colonize the scalp in androgenetic alopecia (AGA). No AGA-specific SSRs were found in the M. globosa IGS region, whereas a (CT)₆ :(AT)₈ SSR was predominantly detected in the M. restricta IGS region in the AGA group. Malassezia colonization was higher in the scalps of patients with M. restricta (CT)₆ :(AT)₈ SSRs than in the scalps of patients without M. restricta (CT)₆ :(AT)₈ SSRs. These observations suggest that this specific SSR type in M. restricta is involved in the development or exacerbation of AGA. This article is protected by copyright. All rights reserved.

Fatal fungemia by biofilm-producing Trichosporon asahii in a liver transplant candidate

Acute-on-chronic liver failure (ACLF) is often associated with a dismal outcome. Infections might preclude access to liver transplantation (LT) for these patients, further reducing their chance of survival. We report the case of a patient with ACLF who died before LT for biofilm-producing Trichosporon asahii fungemia. The patient early started antifungal therapy with anidulafungin, but T. asahii was not susceptible to echinocandins, delaying the start of active antifungal therapy. Although rare, invasive infections by Trichosporon spp. are associated with high mortality rates due to low antimicrobial susceptibility and production of biofilms on indwelling devices. Early diagnosis and treatment are crucial to reduce mortality and enhance patient survival.

MALDI-TOF MS characterisation, genetic diversity and antifungal susceptibility of Trichosporon species from Iranian clinical samples

BACKGROUND

Trichosporonosis is an emerging fungal infection caused by Trichosporon species, a genus of yeast-like fungi, which are frequently encountered in human infections ranging from mild cutaneous lesions to fungemia in immunocompromised patients. The incidence of trichosporonosis has increased in recent years, owing to higher numbers of individuals at risk for this infection. Although amphotericin B, posaconazole and isavuconazole are generally effective against Trichosporon species, some isolates may have variable susceptibility to these antifungals.

OBJECTIVES

Herein, we evaluated the species distribution, genetic diversity and antifungal susceptibility profiles of Trichosporon isolates in Iran.

METHODS

The yeasts were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Phylogenetic analysis was performed based on amplified fragment length polymorphism (AFLP). The in vitro susceptibilities of eight antifungal agents were analysed using the Clinical and Laboratory Standards Institute broth microdilution methods.

RESULTS

The isolates belonged to the species T asahii (n = 20), T japonicum (n = 4) and T faecale (n = 3). A dendrogram of the AFLP analysis demonstrated that T asahii and non-asahii Trichosporon strains (T japonicum and T faecale) are phylogenetically distinct. While voriconazole was the most active agent (GM MIC = 0.075 μg/ml), high fluconazole MICs (8 μg/ml) were observed for a quarter of Trichosporon isolates. The GM MIC value of amphotericin B for T asahii and non-asahii Trichosporon species was 0.9 μg/ml.

CONCLUSIONS

The distribution and antifungal susceptibility patterns of the identified Trichosporon species could inform therapeutic choices for treating these emerging life-threatening fungi.