Pseudozyma aphidis fungaemia with invasive fungal pneumonia in a patient with acute myeloid leukaemia: case report and literature review

High-quality genome resource of a basidiomycetous yeast, Moesziomyces antarcticus isolate RS1, isolated from rice seed

Moesziomyces antarcticus (anamorph: Pseudozyma antarctica) is a basidiomycetous yeast in the Ustilaginaceae family and is a core member of the rice seed microbiome. M. antarcticus RS1 was isolated from surface-sterilized rice seeds. This 18.287 Mb draft genome of M. antarcticus RS1 is comprised of a 60.8% GC content and 6,817 protein-coding genes.

First Case of Subcutaneous Mycoses Caused by Dirkmeia churashimaensis and a Literature Review of Human Ustilaginales Infections

Objective

Dirkmeia churashimaensis, belonging to Ustilaginales fungi, has never been reported as clinical pathogenic until very recently. In this study, we report an unusual subcutaneous infection with Dirkmeia churashimaensis and reviewed all human Ustilaginales infections. The aim is to better understand their epidemiology, infection type, risk factors, and the sensitivity to antifungal agents.

Methods

An 80-year-old female farmer developed extensive plaques and nodules on her left arm within 2 years. Pathological and microbiological examinations identified a new pathological agent, Dirkmeia churashimaensis, as the cause of this infection. The patient was successfully cured by oral itraconazole. We reviewed a total of 31 cases of Ustilaginales cases, among of which only three were skin infections.

Results

Local barrier damage (i.e., surgery, trauma, and basic dermatosis) and systemic immunodeficiency (i.e., preterm and low birthweight, Crohn’s disease, malignant cancer, and chemotherapy) are risk factors for Ustilaginales infection. The D1/D2 and ITS regions are the frequently used loci for identifying the pathogens together with phenotype. Most patients could survive due to antifungal treatment, whereas seven patients died. Amphotericin B, posaconazole, itraconazole, and voriconazole showed good activity against these reported strains, whereas fluconazole, 5-flucytosine, and echinocandins usually showed low susceptibility. Itraconazole had good efficiency for subcutaneous infections.

Conclusions

The present case study and literature review reveal that Ustilaginales can be opportunistic pathogenic normally in immunocompromised and barrier damage people. A proper identification of fungi can be crucial for clinical treatment, and more data of antifungal are needed for choice of medication against this kind of infections.

Pseudozyma spp. human infections: A systematic review

Pseudozyma spp. are described as environmental yeasts but have also been identified as rare human pathogens found in immunocompromised patients. This systematic review details the clinical manifestations, diagnostic methodology, and empirical anti-fungal therapy for this rare yeast. PubMed, LILACS, Scielo, and Web of Science databases were searched for articles about Pseudozyma spp. infections from inception to June 2019. Inclusion criteria were any published studies that included patients with Pseudozyma spp. infection. Infections were identified using criteria set forth by the European Organization for Research and Treatment of Cancer, and were further classified according to clinical, laboratory, or radiologic findings, microbiologic confirmation, and response to therapy. Eleven articles were included with 15 patients. Oncological and/or hematological disorders were the most reported risk factors. Nontraditional microbiological methods correctly identified Pseudozyma spp., whereas traditional methods failed to identify fungal genus. Species were identified by sequencing, and most demonstrated a higher minimal inhibitory concentration (MIC) for fluconazole and echinocandins. MICs for itraconazole, voriconazole, and posaconazole varied by species. All isolates were susceptible to amphotericin B, which was the most used treatment. Pseudozyma spp. infections usually present with fever and are diagnosed by blood culture. Most species studied appeared to be resistant to fluconazole and echinocandin. Voriconazole, posaconazole, and amphotericin were effective in treating P. aphidis. However, more studies are needed to evaluate voriconazole and posaconazole in species other than P. aphidis.

Pseudozyma aphidis bloodstream infection in a patient with aggressive lymphoma and a history of intravenous drug use: Case report and review of the literature

Pseudozyma aphidis is an environmental fungus which causes opportunistic infections in immunocompromised patients. Here we report the case of a 54-year-old, intravenous drug user woman, newly diagnosed to have an aggressive lymphoma, who developed a bloodstream infection caused by P. aphidis treated successfully with amphotericin-B therapy. The precise identification was assessed by sequencing. We propose to consider intravenous drug use as a risk factor for invasive infections due to this environmental yeast.

Investigating the Smuts: Common Cues, Signaling Pathways, and the Role of MAT in Dimorphic Switching and Pathogenesis

The corn smut fungus Ustilago maydis serves as a model species for studying fungal dimorphism and its role in phytopathogenic development. The pathogen has two growth phases: a saprobic yeast phase and a pathogenic filamentous phase. Dimorphic transition of U. maydis involves complex processes of signal perception, mating, and cellular reprogramming. Recent advances in improvement of reference genomes, high-throughput sequencing and molecular genetics studies have been expanding research in this field. However, the biology of other non-model species is frequently overlooked. This leads to uncertainty regarding how much of what is known in U. maydis is applicable to other dimorphic fungi. In this review, we will discuss dimorphic fungi in the aspects of physiology, reproductive biology, genomics, and molecular genetics. We also perform comparative analyses between U. maydis and other fungi in Ustilaginomycotina, the subphylum to which U. maydis belongs. We find that lipid/hydrophobicity is a potential common cue for dimorphic transition in plant-associated dimorphic fungi. However, genomic profiles alone are not adequate to explain dimorphism across different fungi.

Pseudozyma aphidis endophthalmitis post-cataract operation: Case discussion and management

Purpose

To present a case of fungal endophthalmitis with a novel organism and our management.

Observations

A 46 year old male presented with delayed-onset acute endophthalmitis 6 weeks after routine phacoemulsification and intraocular lens implantation. Initial treatment with intravitreal antibiotics did not improve his condition. With repeated vitreal taps, the causative organism was eventually identified as a fungus, Pseudozyma aphidis. Treatment with oral and intravitreal voriconazole, as well as pars plana vitrectomy, led to resolution of the endophthalmitis and recovery of vision to 20/25.

Conclusions and importance

Fungal endophthalmitis is a rare, potentially blinding complication of cataract surgery. We report our approach to this previously unreported organism, that led to an excellent visual outcome. There are no specific guidelines for fungal endophthalmitis. The management approach has to be tailored to the clinical response and emerging laboratory data from the microbiologist. Identification of the organism will require specialist laboratory references that may not be available in all hospitals. Ophthalmologists must work closely with microbiologists in order to ensure an optimal outcome.

Morphology and Molecular Analysis of Moesziomyces antarcticus Isolated From the Blood Samples of a Chinese Patient

Objective: To identify the pathogen causing fungemia in a Chinese patient and describe its morphological and molecular characterizes. Methods: Samples of central and peripheral venous blood were collected for blood culture. Morphology and drug sensitivities of the isolated yeast-like fungus were analyzed. rDNA sequencing and molecular phylogenetic analysis of the isolated strains were performed using DNAMAN and MEGA software. Results: A strain of yeast-like fungi was repeatedly isolated from blood samples of a Chinese patient. The isolates grew well on sabouraud medium broth plate. The colonies were smooth and round at 28°C, and were of rough surface and irregular shape at 35°C. Molecular phylogenetic trees constructed based on the internal transcribed spacer (ITS) and D1/D2 domains of 28S rDNA gene demonstrated the isolated yeast-like fungus was Moesziomyces antarcticus. Drug susceptibility test showed that this isolated M. antarcticus was resistant or had relatively low susceptibility to flucytosine, fluconazole, voriconazole, and itraconazole, and only sensitive to amphotericin. Conclusion: This study provided more information for the molecular and morphology characteristics of M. antarcticus and reviewed the species information of Moesziomyces associated with human infections, which will contribute to the identification and diagnosis of Moesziomyces infections.

Pseudozyma and other non-Candida opportunistic yeast bloodstream infections in a large stem cell transplant center

Non-Candida opportunistic yeasts are emerging causes of bloodstream infection (BSI) in immunocompromised hosts. However, their clinical presentation, management, and outcomes in stem cell transplant (SCT) recipients are not well described. We report the first case to our knowledge of Pseudozyma BSI in a SCT recipient. He had evidence of cutaneous involvement, which has not been previously described in the literature. He became infected while neutropenic and receiving empiric micafungin, which is notable because Pseudozyma is reported to be resistant to echinocandins. He was successfully treated with the sequential use of liposomal amphotericin B and voriconazole. A review of the literature revealed nine reported instances of Pseudozyma fungemia. We performed a retrospective review of 3557 SCT recipients at our institution from January 2000 to June 2015 and identified four additional cases of non-Candida yeast BSIs. These include two with Cryptococcus, one with Trichosporon, and one with Saccharomyces. Pseudozyma and other non-Candida yeasts are emerging pathogens that can cause severe and disseminated infections in SCT recipients and other immunocompromised hosts. Clinicians should have a high degree of suspicion for echinocandin-resistant yeasts, if patients develop breakthrough yeast BSIs while receiving echinocandin therapy.