First fungemia case due to environmental yeast Wickerhamomyces myanmarensis: detection by multiplex qPCR and antifungal susceptibility

Diversity of Wickerhamomyces (Wickerhamomycetaceae, Saccharomycetales) in China with the description of four new species

Wickerhamomyces is a well-known genus of the family Wickerhamomycetaceae in the class Ascomycetes. These fungi can survive in a variety of substrates and environments and perform many valuable roles in both industrial processes and the natural ecosystems. During our investigation of yeast diversity associated with plant materials, 53 Wickerhamomyces isolates were obtained from rotting wood and plant leaves collected in Fujian, Guizhou, Henan, and Yunnan Provinces of China. Isolates were identified as 14 Wickerhamomyces species, including 1 species known previously to occur in China (W. anomalus), 9 new record species in China (W. arborarius, W. ciferrii, W. edaphicus, W. lynferdii, W. pijperi, W. subpelliculosa, W. xylosica, W. strasburgensis, and W. sydowiorum), and 4 novel species (W. guiyangensis sp. nov., W. paramyanmarensis sp. nov., W. quanzhouensis sp. nov., and W. phyllophilus sp. nov.). This study presents a detailed account of these new species, illustrating their morphology and analyzing their phylogenetic relationships with other Wickerhamomyces species. Our study is the first comprehensive study on Wickerhamomyces species associated with plant materials from tropical and subtropical China. The results of this study update our understanding of the phylogenetic relationships, systematics, and ecology of Wickerhamomyces.

Port implantation-related bloodstream infection caused by Wickerhamomyces myanmarensis: A case report

Background and Purpose

Wickerhamomyces myanmarensis is a new opportunistic yeast previously named Pichai myanmarensis, which belongs to the order Saccharomycetales. Since its discovery, one environmental isolate of W. myanmarensis has been reported from Myanmar, and one clinical sample from Iran.

Case Report

We report a case of bloodstream infection related to an implantable venous access port. W. myanmarensis was isolated from patient's blood after chemotherapy, which was meant to control and heal T-cell lymphoblastic lymphoma. Broth dilution minimum inhibitory concentrations were performed according to the CLSI M27-A3 document. The patient recovered with intravenous voriconazole and was discharged with the recommended prescription of oral voriconazole as a maintenance drug.

Conclusion

So far, only one case of W. myanmarensis fungemia has been reported in the world in 2019. This is the second case of bloodstream infection with this yeast from a patient undergoing chemotherapy in Iran.

Yeasts originating from fermented foods, their potential as probiotics and therapeutic implication for human health and disease

Yeasts derived from fermented foods have historically been known for their organoleptic properties, enriching nutritional values, and producing bioactive metabolites with therapeutic potential. In this review, we discuss the yeast flora in fermented foods, their functional aspects in fermentation, as well as their probiotic and biotherapeutic properties. These yeasts have numerous physical and biochemical characteristics, such as larger cells as compared to bacteria, a rigid cell wall composed primarily of glucans and mannans, natural resistance to antibiotics, and the secretion of secondary metabolites that are both pleasing to the consumer and beneficial to the host's health and well-being. The review also focused on therapeutic applications of probiotic yeasts derived from fermented foods on infections associated with Candida species. These potential probiotic yeasts present an additional avenue to treat dysbiosis of the gut microbiota and prevent health complications that arise from opportunistic fungal colonization, especially drug-resistant superbugs, which are highlighted in this review.

An Updated Global Species Diversity and Phylogeny in the Genus Wickerhamomyces with Addition of Two New Species from Thailand

Ascomycetous yeast species in the genus Wickerhamomyces (Saccharomycetales, Wickerhamomycetaceae) are isolated from various habitats and distributed throughout the world. Prior to this study, 35 species had been validly published and accepted into this genus. Beneficially, Wickerhamomyces species have been used in a number of biotechnologically applications of environment, food, beverage industries, biofuel, medicine and agriculture. However, in some studies, Wickerhamomyces species have been identified as an opportunistic human pathogen. Through an overview of diversity, taxonomy and recently published literature, we have updated a brief review of Wickerhamomyces. Moreover, two new Wickerhamomyces species were isolated from the soil samples of Assam tea (Camellia sinensis var. assamica) that were collected from plantations in northern Thailand. Herein, we have identified these species as W. lannaensis and W. nanensis. The identification of these species was based on phenotypic (morphological, biochemical and physiological characteristics) and molecular analyses. Phylogenetic analyses of a combination of the internal transcribed spacer (ITS) region and the D1/D2 domains of the large subunit (LSU) of ribosomal DNA genes support that W. lannaensis and W. nanensis are distinct from other species within the genus Wickerhamomyces. A full description, illustrations and a phylogenetic tree showing the position of both new species have been provided. Accordingly, a new combination species, W. myanmarensis has been proposed based on the phylogenetic results. A new key for species identification is provided.

A high-risk airway mycobiome is associated with frequent exacerbation and mortality in COPD

INTRODUCTION

The chronic obstructive pulmonary disease (COPD) bacteriome associates with disease severity, exacerbations and mortality. While COPD patients are susceptible to fungal sensitisation, the role of the fungal mycobiome remains uncertain.

METHODS

We report the largest multicentre evaluation of the COPD airway mycobiome to date, including participants from Asia (Singapore and Malaysia) and the UK (Scotland) when stable (n=337) and during exacerbations (n=66) as well as nondiseased (healthy) controls (n=47). Longitudinal mycobiome analysis was performed during and following COPD exacerbations (n=34), and examined in terms of exacerbation frequency, 2-year mortality and occurrence of serum specific IgE (sIgE) against selected fungi.

RESULTS

A distinct mycobiome profile is observed in COPD compared with controls as evidenced by increased α-diversity (Shannon index; p<0.001). Significant airway mycobiome differences, including greater interfungal interaction (by co-occurrence), characterise very frequent COPD exacerbators (three or more exacerbations per year) (permutational multivariate ANOVA; adjusted p<0.001). Longitudinal analyses during exacerbations and following treatment with antibiotics and corticosteroids did not reveal any significant change in airway mycobiome profile. Unsupervised clustering resulted in two clinically distinct COPD groups: one with increased symptoms (COPD Assessment Test score) and Saccharomyces dominance, and another with very frequent exacerbations and higher mortality characterised by Aspergillus, Curvularia and Penicillium with a concomitant increase in serum sIgE levels against the same fungi. During acute exacerbations of COPD, lower fungal diversity associates with higher 2-year mortality.

CONCLUSION

The airway mycobiome in COPD is characterised by specific fungal genera associated with exacerbations and increased mortality.

Fatal Case of Fungemia by Wickerhamomyces anomalus in a Pediatric Patient Diagnosed in a Teaching Hospital from Brazil

In recent decades, emerging fungal infections have changed the clinical mycology scenario as a consequence of the advances in medical diagnostics and therapeutic procedures, long hospitalization times, and the growing number of individuals with debilitating chronic diseases and impaired immune systems. This report presents a 19 months old Brazilian female patient who developed a severe fungal sepsis by an uncommon yeast. She was admitted at the intensive care unit with severe pneumonia, bronchopulmonary dysplasia, and weight-for-age z score of less than −2. She remained more than 30 days in the intensive care unit where she had a femoral venous catheter placement, enteral nutrition, broad-spectrum antibiotic therapy, and prophylaxis with fluconazole. Moreover, pericardiocentesis was performed due to cardiac tamponade. She had a previous history of prematurity, cardiac surgery due to patent ductus arteriosus, and a long period of hospital stay. Despite the antifungal prophylaxis, two yeast isolates were recovered from blood and then identified by classical mycological methods and internal transcribed spacer (ITS) sequencing as Wickerhamomyces anomalus. Both isolates exhibited susceptibility to amphotericin B, ketoconazole, itraconazole, voriconazole, and fluconazole. Her clinical state worsened, presenting anasarca, epistaxis, and hemorrhagic suffusions in the mouth, sclera, oliguria, and bradycardia. Two days after the first positive culture, she presented a gradual reduction of the white blood cells count, with severe leukopenia and neutropenia. She died five days after.

Epidemiology of candidemia in Shiraz, southern Iran: A prospective multicenter study (2016-2018)

Systematic candidemia studies, especially in southern Iran, are scarce. In the current prospective study, we investigated candidemia in three major healthcare centers of Shiraz, the largest city in southern Iran. Yeast isolates from blood and other sterile body fluids were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and subjected to antifungal susceptibility testing (AFST) using the broth microdilution method. Clinical data were retrieved from patients' medical records. In total, 113 yeast isolates were recovered from 109 patients, over 60% of whom received fluconazole. Antifungal drugs were prescribed without considering species identification or AFST. The all-cause mortality rate was 28%. Almost 30% of the patients were from intensive care units (ICUs). Candida albicans (56/113; 49.5%) was the most prevalent species followed by C. glabrata (26/113; 23%), C. parapsilosis (13/113; 11.5%), C. tropicalis (7/113; 6.2%), and C. dubliniensis (5/113; 4.4%). Only five isolates showed antifungal resistance or decreased susceptibility to fluconazole: one C. orthopsilosis isolate from an azole-naïve patient and two C. glabrata, one C. albicans, and one C. dubliniensis isolates from patients treated with azoles, who developed therapeutic failure against azoles later. Our results revealed a low level of antifungal resistance but a notable rate of azole therapeutic failure among patients with candidemia due to non-albicans Candida species, which threaten the efficacy of fluconazole, the most widely used antifungal in southern regions of Iran. Candidemia studies should not be confined to ICUs and treatment should be administered based on species identification and AFST results.

Identification of Mycoses in Developing Countries

Extensive advances in technology offer a vast variety of diagnostic methods that save time and costs, but identification of fungal species causing human infections remains challenging in developing countries. Since the echinocandins, antifungals widely used to treat invasive mycoses, are still unavailable in developing countries where a considerable number of problematic fungal species are present, rapid and reliable identification is of paramount importance. Unaffordability, large footprints, lack of skilled personnel, and high costs associated with maintenance and infrastructure are the main factors precluding the establishment of high-precision technologies that can replace inexpensive yet time-consuming and inaccurate phenotypic methods. In addition, point-of-care lateral flow assay tests are available for the diagnosis of Aspergillus and Cryptococcus and are highly relevant for developing countries. An Aspergillus galactomannan lateral flow assay is also now available. Real-time PCR remains difficult to standardize and is not widespread in countries with limited resources. Isothermal and conventional PCR-based amplification assays may be alternative solutions. The combination of real-time PCR and serological assays can significantly increase diagnostic efficiency. However, this approach is too expensive for medical institutions in developing countries. Further advances in next-generation sequencing and other innovative technologies such as clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostic tools may lead to efficient, alternate methods that can be used in point-of-care assays, which may supplement or replace some of the current technologies and improve the diagnostics of fungal infections in developing countries.