Saprochaete clavata Invasive Infections - A New Threat to Hematological-Oncological Patients

Background

Saprochaete clavata (formerly Geotrichum clavatum, now proposed as Magnusiomyces clavatus) is a filamentous yeast-like fungus that has recently been described as an emerging pathogen mostly in patients with acute leukemia.

Methods

This is a retrospective study of patients diagnosed with proven and probable S. clavata infection at the University Hospital, Hradec Králové, Czechia between March 2005 and December 2017. Previous cases were identified from the literature and FungiScope^® database.

Results

Six new cases (5 females, 1 male) of blood-stream S. clavata infections at the hemato-oncological department were described including epidemiological data of additional 48 patients colonized with the species. Overall, 116 strains of S. clavata were isolated from different clinical specimens of 54 patients; most of them belonged to the respiratory tract (60.3%). S. clavata was the most frequent species among arthroconidial yeasts (Trichosporon, Galactomyces, Magnusiomyces) recovered from the blood. All our patients with S. clavata infection had profound neutropenia, a central venous catheter, broad-spectrum antibiotics and antifungal prophylaxis; four had a history of a biliary tract system disease. The diagnosis was based on a positive blood culture in all patients. Four patients died of multiorgan failure and sepsis despite treatment with lipid-based amphotericin B and/or voriconazole. From the literature and FungiScope database, 67 previous cases of S. clavata infections were evaluated in context of our cases.

Conclusion

Saprochaete clavata infection represents a life-threatening mycosis in severely immunocompromised patients. The successful outcome of treatment seems to be critically dependent on the early diagnosis and the recovery of underlying conditions associated with immune dysfunction or deficiency.

Molecular Diagnostics of Arthroconidial Yeasts, Frequent Pulmonary Opportunists

Magnusiomyces capitatus and Saprochaete clavata are members of the clade of arthroconidial yeasts that represent emerging opportunistic pulmonary pathogens in immunocompromised patients. Given that standard ribosomal DNA (rDNA) identification often provides confusing results, in this study, we analyzed 34 isolates with the goal of finding new genetic markers for classification using multilocus sequencing and amplified fragment length polymorphism (AFLP). The interspecific similarity obtained using rDNA markers (the internal transcribed spacer [ITS] and large subunit regions) was in the range of 96 to 99%, whereas that obtained using protein-coding loci (Rbp2, Act, and Tef1α) was lower at 89.4 to 95.2%. Ultimately, Rbp2 was selected as the best marker for species distinction. On the basis of cloned ITS data, some strains proved to be misidentified in comparison with the identities obtained with phenotypic characters, protein sequences, and AFLP profiles, indicating that different copies of the ribosomal operon were present in a single species. Antifungal susceptibility testing revealed that voriconazole had the lowest MIC against M. capitatus, while amphotericin B had the lowest MIC against S. clavata Both species exhibited in vitro resistance to fluconazole and micafungin.

Yeast-like filamentous fungi: Molecular identification and in vitro susceptibility study

Yeast-like filamentous fungi, collected in Italy from 1985 to 2018, were submitted to molecular identification and antifungal susceptibility testings. Clinical isolates were identified as Magnusiomyces capitatus (28), M. clavatus (18), and Geotrichum candidum (2). M. clavatus was prevalent among blood isolates (18/24), M. capitatus among isolates from other biological materials. The intrinsic echinocandin resistance was confirmed. Both species had low minimum inhibitory concentrations (MICs) of itraconazole, posaconazole, and voriconazole, while M. clavatus had lower MIC of flucytosine and higher MIC of isavuconazole than M. capitatus. The intrinsic resistance of these species to echinocandins could be the reason of the recent increase of M. clavatus bloodstream infections.

Degradation of Vinyl Alcohol Oligomers by Geotrichum sp. WF9101

Geotrichum sp. WF9101 isolated from a poly (vinyl alcohol)-degrading mixed culture could utilized vinyl alcohol oligomers, but not the polymers. This strain is proposed to have utilized degradation products of poly (vinyl alcohol) in the mixed culture. Biodegradation of vinyl alcohol oligomers by this strain was discussed using 2,4-pentanediol as a model substrate.

Flavour production by Saprochaete and Geotrichum yeasts and their close relatives

In this study, a total of 30 yeast strains belonging to the genera Dipodascus, Galactomyces, Geotrichum, Magnusiomyces and Saprochaete were investigated for volatile organic compound production using HS-SPME-GC/MS analysis. The resulting flavour profiles, including 36 esters and 6 alcohols compounds, were statistically evaluated by cluster and PCA analysis. Two main groups of strains were extracted from this analysis, namely a group with a low ability to produce flavour and a group producing mainly alcohols. Two other minor groups of strains including Saprochaete suaveolens, Geotrichum marinum and Saprochaete gigas were diverging significantly from the main groups precisely because they showed a good ability to produce a large diversity of esters. In particular, we found that the Saprochaete genus (and their closed relatives) was characterized by a high production of unsaturated esters arising from partial catabolism of branched chain amino-acids. These esters were produced by eight phylogenetically related strains of Saprochaete genus.

First case of invasive Magnusiomyces capitatus infection in Slovakia

Magnusiomyces capitatus (previously known as Geotrichum capitatum or Blastoschizomyces capitatus or Trichosporon capitatum) is a rare cause of fungal infection in immunocompromised patients. Most of these cases (87%) have been reported from the Mediterranean region, as it is extremely rare to recognize it in other regions. Here we report a first case of disseminated M. capitatus infection in Slovakia. The patient – 19 year old woman with myelodysplastic syndrome was diagnosed with M. capitatus fungemia after allogeneic stem cell transplantation. The infection occurred despite antifungal prophylaxis with micafungin, which was in vitro sensitive to the yeast. The treatment according to minimal inhibitory concentrations (micafungin, voriconazol) and granulocyte transfusions were administered. M. capitatus was cleared out from the bloodstream. However, patient died of multiple organ failure. Autopsy showed multiple lesions in organs, but did not prove presence of yeast by histopathology. M. capitatus was confirmed by polymerase chain reaction from all tested organs: heart, brain, lungs, spleen, liver and kidneys. We present the post mortem pictures showing the yeast lesions in affected organs. 2012 Elsevier Ltd. All rights reserved.

[Nondermatophytic and noncandidal fungi isolated in Le Dantec University hospital of Dakar in 2014: Epidemiological, clinical and mycological study]

In recent years, the incidence of superficial fungal infections involving nondermatophytic and noncandidal fungi increased considerably. The objective of this work was to analyze the epidemiological, clinical and mycological fungal infections due to nondermatophytic and noncandidal fungi diagnosed in the laboratory of parasitology-mycology of Le Dantec hospital in Dakar. With a retrospective study of the various cases of nondermatophytic and noncandidal fungi isolated in the laboratory of parasitology-mycology during the period of November 2013 to December 2014, we collected 22 cases of infections in 11 men and 11 women; age ranging from 17 to 75 years with a mean of 45.3 years (sex ratio=1): eight cases of intertrigo, seven cases of onychomycosis, four cases of palmoplantar keratoderma (KPP), a case of onychomycosis associated with interdigital intertrigo, a case of infectious myositis and one case of African histoplasmosis. We have isolated and identified a total of 22 nondermatophytic and noncandidal fungi: ten Fusarium, five Trichosporon, two Chrysosporium, two Geotrichum, one Rhodotorula, one Neoscytalidium dimidiatum and one Histoplasma capsulatum var. duboisii. So we are seeing the emergence of nondermatophytic and noncandidal increasingly isolated from superficial and local lesions. These fungi, generally contaminants or commensal, cause a problem regarding their direct involvement in pathological processes in which they are isolated. So we should respect the recommendations proposed for their involvement in pathological processes and, by a collaboration between clinician and biologist, demonstrate their real involvement through effective, targeted treatment.

Scytalidium candidum 3C is a new name for the Geotrichum candidum Link 3C strain

In the 1970s, the strain Geotrichum candidum Link 3C was isolated from rotting rope and since then has been extensively studied as a source of cellulose and xylan-degrading enzymes. The original identification of the strain was based only on morphological characters of the fungal mycelium in culture. Recent comparison of the internal transcribed spacer (ITS) fragments derived from the draft genome published in 2015 did not show its similarity to G. candidum species. Given the value of the strain 3C in lignocellulosic biomass degradation, we performed morphological and molecular studies to find the appropriate taxonomic placement for this fungal strain within the Ascomycota phylum. ITS, 18S rDNA, 28S rDNA sequences, and RPB2 encoding genes were used to construct phylogenetic trees with Maximum likelihood and Bayesian inference methods. Based on sequence comparison and multiple gene sequencing, we conclude that the fungal strain designated as Geotrichum candidum Link 3C should be placed into the genus Scytalidium (Pezizomycotina, Leotiomycetes) and is redescribed herein as Scytalidium candidum 3C comb. nov.

[Disseminated fungal infection due to Magnusiomyces capitatus in a liver graft patient]

Disseminated fungal infections due to Magnusiomyces capitatus are rare, occurring exclusively in immunocompromised patients. We report the first case in a liver transplant patient with chronic rejection and portal thrombosis who had a M. capitatus fungemia with a refractory septic shock. Despite an antibacterial and antifungal treatment with caspofungin empirical treatment, the patient died from multiple organ failure. Subsequently, mycological examinations of blood cultures, bronchoalveolar lavage fluid and urine were positive to M. capitatus identified by mass spectrometry and confirmed by sequencing respectively. The stain was resistant to caspofungin and fluconazole. The best treatment appears to be the combination of amphotericin B and voriconazole or amphotericin B and 5 fluorocytosine.

Galactomyces candidus diversity in the complex mycobiota of cow-milk bryndza cheese comprising antagonistic and sensitive strains

Galactomyces candidus (orthographic variant: Galactomyces candidum) is a heterogeneous species of Saccharomycetales that comprises dimorphic yeasts described previously under various names (e.g. Geotrichum, Dipodascus). Its strains are common components of the cheese surface mycobiota. This study identified genetically and physiologically heterogeneous G. candidus strains in the complex mycobiota of artisanal cow-milk bryndza samples. The traditional Slovak bryndza is a cheese produced from ewe's milk in cooler mountainous regions and from cow's milk in warmer low-land regions. The taxonomic analysis of the culturable yeasts of the latter version carried out in this study revealed considerable differences from the yeast biota previously described for ovine bryndza. However, the conventional D1/D2- and ITS-based barcode analyses could not assign unanimously all isolates to species because of the intragenomic barcode diversity in certain groups and the discordance between the D1/D2 and ITS results in other groups. The identified species and groups of isolates had different abilities to utilise the carbon and energy sources (lactose, lactate, lipids and proteins) available in milk and ripening cheese. The G. candidus strains did not metabolise lactose and lactate, hydrolysed milk proteins with diverse, usually moderate efficiency and only could grow on certain amino acids as only energy sources. Their preferred substrate was lipid. Under aerobic conditions, its hyphae penetrated the lipid droplets and degraded their content from inside by developing a dense internal mycelium. Sporulation and different MLST (multilocus sequence typing) patterns indicated that the Galactomyces strains could sexually interact and their genomes could recombine. The Galactomyces and Kluyveromyces isolates had antagonistic effects against other members of the mycobiota.

Phenotypic and molecular genetics study of Geotrichum candidumLink (1809) and Geotrichum silvicola Pimenta (2005) cultivated on mitis salivarius agar

BACKGROUND

Geotrichum is a genus of fungi found in different habitats throughout the world. Although Geotrichum and its related species have been extensively reclassified and taxonomically revised, it is still the target for many researches.

METHODS AND RESULTS

In this study, phenotypic and molecular genetics comparisons were performed between Geotrichum candidum and Geotrichum silvicola. Mitis Salivarius Agar was used as the growing medium for the phenotypic comparison study, which was carried out at two temperatures (20-25 and 37 °C). For genotypic comparison, we compared the 18 S, ITS, and 28 S sequences of universal DNA barcode regions of both species. Important findings on the new culture media for fungal isolation were revealed by the results. The phenotypic variation between the two species' colonies, including their shapes, sizes, textures and growth rates, were strikingly different. DNA sequences of both species showed that pairwise identities of the species were 99.9% for 18 S, 100% for ITS and 99.6% for 28 S regions.

CONCLUSIONS

Contrary to what is commonly seen, the results showed that 18 S, ITS and 28 S failed to discriminate the species. The first investigation into the performance of Mitis Salivarius Agar as a fungus culture medium is reported in this work, and proved its efficiency. Additionally, this is the first study to compare G. candidum with G. silvicola by means of both phenotypic and genotypic analysis.

Clincial features and prognostic factors of magnusiomyces (saprochaete) infections in hematology. a multicenter study of seifem/fungiscope

BACKGROUND

Our multicenter study aims to identify baseline factors and provide guidance for therapeutic decisions regarding Magnusiomyces-associated infections, an emerging threat in patients with hematological malignancies.

METHODS

HM patients with proven M. capitatus or M. clavatus (formerly Saprochaete capitata and Saprochaete clavata) infection diagnosed between January 2010 and December 2020 were recorded from the SEIFEM (Sorveglianza Epidemiologica Infezioni nelle Emopatie) group and FungiScope (Global Emerging Fungal Infection Registry). Cases of Magnusiomyces fungemia were compared with candidemia.

RESULTS

Among 90 Magnusiomycescases (60 [66%] M. capitatus and 30 (34%) M. clavatus), median age was 50 years (range 2-78), 46 patients (51%) were female and 67 (74%) had acute leukemia. Thirty-six (40%) of Magnusiomyces-associated infections occurred during antifungal prophylaxis, mainly with posaconazole (n=13, 36%) and echinocandins (n=12, 34%). Instead, the candidemia rarely occurred during prophylaxis (p<0.0001). First-line antifungal therapy with azoles, alone or in combination, was associated with improved response compared to other antifungals (p=0.001). Overall day-30 mortality rate was 43%. Factors associated with higher mortality rates were septic shock (HR 2.696, 95%CI 1.396-5.204, p=.003), corticosteroid treatment longer than 14 days (HR 2.245, 95%CI 1.151-4.376, p=.018), and lack of neutrophil recovery (HR 3.997, 95%CI 2.102-7.601, p<.001). The latter was independently associated with poor outcome (HR 2.495, 95%CI 1.192-5.222, p=.015).

CONCLUSIONS

Magnusiomyces-associated infections are often breakthrough infections. Effective treatment regimens of these infections remain to be determined, but neutrophil recovery appears to play an important role in the favorable outcome.

Impact of Dietary Regime and Seasonality on Hindgut's Mycobiota Diversity in Dairy Cows

We describe and discuss the intestinal mycobiota of dairy cows reared in France following variations in dietary regimes and two seasons. Two groups of 21 animals were followed over a summer and winter period, and another group of 28 animals was followed only during the same summer season. The summer diet was based on grazing supplemented with 3-5 kg/d of maize, grass silage and hay, while the winter diet consisted of 30% maize silage, 25% grass silage, 15% hay and 30% concentrate. A total of 69 DNA samples were extracted from the feces of these cows. Amplification and sequencing of the ITS2 region were used to assess mycobiota diversity. Analyses of alpha and beta diversity were performed and compared statistically. The mycobiota changed significantly from summer to winter conditions with a decrease in its diversity, richness and evenness parameters, while beta diversity analysis showed different mycobiota profiles. Of note, the Geotrichum operational taxonomic unit (OTU) was prevalent in the winter group, with a mean relative abundance (RA) of 65% of the total mycobiota. This Geotrichum OTU was also found in the summer group, but to a lesser extent (5%). In conclusion, a summer grazing diet allowed a higher fecal fungal diversity. These data show, for the first time, that a change in diet associated with seasonality plays a central role in shaping hindgut fungal diversity.

The first case of isolation of Magnusiomyces capitatus from the oral cavity of an addicted patient

Magnusiomyces capitatus (M. capitatus) is an emerging opportunistic yeast, rarely found as a causal agent of invasive fungal infection. In this study, we report a 31-year-old man infected with M. capitatus in the oral cavity, with a history of heroin and amphetamine abuse. M. capitatus was isolated through culture and microscopic analysis and identified by PCR amplification of the ITS DNA region. Based on the in vitro antifungal susceptibility test, the lowest MICs for M. capitatus were recorded for nystatin, itraconazole, and amphotericin, while higher MICs were observed for caspofungin and fluconazole. Treatment with nystatin successfully eliminated M. capitatus and relieved the clinical symptoms. This study presents the first case of M. capitatus in a patient with substance use disorder, manifesting as a plaque-like ulcer in the oral cavity.

Molecular Characterization of Two Totiviruses from the Commensal Yeast Geotrichum candidum

Mycoviruses can infect many of the major taxa of fungi including yeasts. Mycoviruses in the yeast fungus Geotrichum candidum are not well studied with only three G. candidum-associated viral species characterized to date, all of which belong to the Totiviridae genus Totivirus. In this study, we report the molecular characteristics of another two totiviruses co-infecting isolate Gc6 of G. candidum. The two totiviruses were tentatively named Geotrichum candidum totivirus 2 isolate Gc6 (GcTV2-Gc6) and Geotrichum candidum totivirus 4 isolate Gc6 (GcTV4-Gc6). Both viruses have the typical genome organization of totiviruses comprising two ORFs encoding capsid protein (CP) and RNA-dependent RNA polymerase (RdRp) at the N and C termini, respectively. The genomes of GcTV2-Gc6 and GcTV4-Gc6 are 4592 and 4530 bp long, respectively. Both viruses contain the-frameshifting elements and their proteins could be expressed as a single fusion protein. GcTV2-Gc6 is closely related to a totivirus isolated from the same host whereas GcTV4-Gc6 is related to insect-associated totiviruses. The phylogenetic analysis indicated that GcTV2-Gc6 and GcTV4-Gc6 belong to two different sister clades, I-A and I-B, respectively. It is interesting that all viruses identified from G. candidum belong to the genus Totivirus; however, this might be due to the lack of research reporting the characterization of mycoviruses from this fungal host. It is possible that the RNA interference (RNAi) mechanism cannot actively suppress totivirus accumulation in G. candidum Gc6.

Rare Yeasts in Latin America: Uncommon Yet Meaningful

Systemic infections caused by rare yeasts are increasing given the rise in immunocompromised or seriously ill patients. Even though globally, the clinical significance of these emerging opportunistic yeasts is increasingly being recognized, less is known about the epidemiology of rare yeasts in Latin America. This review collects, analyzes, and contributes demographic and clinical data from 495 cases of infection caused by rare yeasts in the region. Among all cases, 32 species of rare yeasts, distributed in 12 genera, have been reported in 8 Latin American countries, with Trichosporon asahii (49.5%), Rhodotorula mucilaginosa (11.1%), and Saccharomyces cerevisiae (7.8%) the most common species found. Patients were mostly male (58.3%), from neonates to 84 years of age. Statistically, surgery and antibiotic use were associated with higher rates of Trichosporon infections, while central venous catheter, leukemia, and cancer were associated with higher rates of Rhodotorula infections. From all cases, fungemia was the predominant diagnosis (50.3%). Patients were mostly treated with amphotericin B (58.7%). Crude mortality was 40.8%, with a higher risk of death from fungemia and T. asahii infections. Culture was the main diagnostic methodology. Antifungal resistance to one or more drugs was reported in various species of rare yeasts.

Two new arthroconidial yeast species from bark and pit mud in China

A study on yeast species from the genera Geotrichum and Magnusiomyces in southwest and central China was conducted based on morphological and molecular phylogenetic analyses using the ITS region and the D1/D2 domain of the LSU rRNA gene. The research identified two new yeast species: Geotrichumhubeiense and Magnusiomycespitmudophilus. The study contributed to understanding arthroconidial yeast diversity in fermentation and natural environments and paved the way for future taxonomic and ecological studies. Descriptions, illustrations, and phylogenetic analysis results of the two new taxa are provided.

The effects of ultrasonic processing on the antioxidant activity of Geotrichum candidum LG-8 and its cell wall extracts

Introduction

Extraction techniques that influence cell wall polysaccharides (EPS) is crucial for maximizing their bioactivity. This study evaluates ultrasound technology for extracting antioxidant polysaccharides from Geotrichum candidum LG-8, assessing its impacton antioxidant activity.

Methods

Ultrasound extraction of EPS from G. candidum LG-8 was optimized (18 min, pH 7.0, 40 W/cm2, 0.75 M NaCl). ABTS scavenging efficiency and monosaccharide composition of LG-EPS1 and LG-EPS3 were analyzed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).

Results

The Results showed that ultrasonic treatment markedly increased the ABTS radical scavenging efficiency of LG-8 cells by 47%. At a concentration of 1 mg/mL, the ultrasonically extracted LG-EPS1 and LG-EPS3 polysaccharides exhibited significant ABTS radical scavenging efficiencies of 26% and 51%, respectively. Monosaccharide composition analysis identified mannose and glucose in LG-EPS1, while LG-EPS3 was primarily composed of mannose. FTIR spectra verified the polysaccharides' presence, and SEM provided visual confirmation of the nanoparticle structures characteristic of LG-EPS1 and LG-EPS3.

Discussion

This research not only underscores the technological merits of ultrasound in polysaccharide extraction but also highlights the potential of G. candidum LG-8 derived polysaccharides as valuable bioactive compounds for antioxidant utilization.

Critically ill patients with severe infections related to Geotrichum species: A French retrospective multicentre study

OBJECTIVES

Geotrichum spp can be responsible for severe infections in immunocompromised patients. We aim to describe Geotrichum-related infections in the ICU and to assess risk factors of mortality.

METHODS

Retrospective multicentre study, conducted in 14 French ICUs between 2002 and 2018, including critically ill adult patients with proven or probable infection related to Geotrichum species. Data were obtained from the medical charts.

RESULTS

Thirty-six patients, median age 60 years IQR [53; 66] were included. Most of the patients had haematological malignancies (78%). The reason for ICU admission was shock in half of the patients (n = 19, 53%) and respiratory failure in thirteen patients (36%). Median SOFA score was 8.5 IQR [7; 15]. Time between ICU admission and fungal diagnosis was 2.5 days [-1; 4]. Infection was disseminated in 27 (75%) patients with positive blood cultures in 25 patients (69%). Thirty patients (83%) received curative antifungal treatment in the ICU, in a median time of 1 day [0;1] after ICU admission. Twenty-four patients (67%) died in the ICU and hospital mortality rate was 69%. The number and extent of organ failures, as represented by SOFA score, were associated with mortality.

CONCLUSIONS

This study demonstrates poor outcome in critically ill patients with Geotrichum-related infections, which encourages a high level of suspicion.