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.

Extracellular Vesicles from Candida haemulonii var. vulnera Modulate Macrophage Oxidative Burst.

Members of the Candida haemulonii species complex are multidrug-resistant emergent yeast pathogens able to cause superficial and invasive infections in risk populations. Fungal extracellular vesicles (EVs) play a critical role in the pathogenicity and virulence of several species and may perform essential functions during infections, such as carrying virulence factors that behave in two-way communications with the host, affecting survival and fungal resistance. Our study aimed to describe EV production from Candida haemulonii var. vulnera and evaluate whether murine macrophage RAW 264.7 cells respond to their stimuli by generating an oxidative response after 24 h. For this purpose, reactive oxygen species detection assays demonstrated that high concentrations of yeast and EVs (1010 particles/mL) of Candida haemulonii did not change macrophage viability. However, the macrophages recognized these EVs and triggered an oxidative response through the classical NOX-2 pathway, increasing O2•- and H2O2 levels. However, this stress did not cause lipid peroxidation in the RAW 264.7 cells and neither lead to the activation of the COX-2-PGE2 pathway. Thus, our data suggest that low concentrations of C. haemulonii EVs are not recognized by the classical pathway of the oxidative burst generated by macrophages, which might be an advantage allowing the transport of virulence factors via EVs, not identified by the host immune system that could work as fine tube regulators during infections caused by C. haemulonii. In contrast, C. haemulonii var. vulnera and high EV concentrations activated microbicidal actions in macrophages. Therefore, we propose that EVs could participate in the virulence of the species and that these particles could be a source of antigens to be exploited as new therapeutic targets.

Novel Non-Hot Spot Modification in Fks1 of Candida auris Confers Echinocandin Resistance.

We determined the echinocandin susceptibility and FKS1 genotypes of 13 clinical isolates of Candida auris that were recovered from 4 patients at a tertiary care center in Salvador, Brazil. Three isolates were categorized as echinocandin-resistant, and they harbored a novel FKS1 mutation that led to an amino acid change W691L located downstream from hot spot 1. When introduced to echinocandin-susceptible C. auris strains by CRISPR/Cas9, Fks1 W691L induced elevated MIC values to all echinocandins (anidulafungin, 16 to 32×; caspofungin, >64×; micafungin, >64×).

Short Tandem Repeat Genotyping and Antifungal Susceptibility Testing of Latin American Candida tropicalis Isolates.

Candida tropicalis is emerging as one of the most common Candida species causing opportunistic infections in Latin America. Outbreak events caused by C. tropicalis were reported, and antifungal resistant isolates are on the rise. In order to investigate population genomics and look into antifungal resistance, we applied a short tandem repeat (STR) genotyping scheme and antifungal susceptibility testing (AFST) to 230 clinical and environmental C. tropicalis isolates from Latin American countries. STR genotyping identified 164 genotypes, including 11 clusters comprised of three to seven isolates, indicating outbreak events. AFST identified one isolate as anidulafungin-resistant and harboring a FKS1 S659P substitution. Moreover, we identified 24 clinical and environmental isolates with intermediate susceptibility or resistance to one or more azoles. ERG11 sequencing revealed each of these isolates harboring a Y132F and/or Y257H/N substitution. All of these isolates, except one, were clustered together in two groups of closely related STR genotypes, with each group harboring distinct ERG11 substitutions. The ancestral C. tropicalis strain of these isolates likely acquired the azole resistance-associated substitutions and subsequently spread across vast distances within Brazil. Altogether, this STR genotyping scheme for C. tropicalis proved to be useful for identifying unrecognized outbreak events and better understanding population genomics, including the spread of antifungal-resistant isolates.

Invasive Aspergillosis in Patients with Acute Leukemia: Comparison Between Acute Myeloid and Acute Lymphoid Leukemia.

BACKGROUND: The epidemiology of invasive aspergillosis (IA) in patients with acute lymphoid leukemia (ALL) has not been well characterized. OBJECTIVES: To identify potential peculiarities in the natural history, treatment response and outcome of IA diagnosed in patients with ALL and AML. METHODS: This is a retrospective cohort study conducted in seven tertiary-care hospitals between 2009 and 2017 of all consecutive episodes of IA occurring in adult patients with acute leukemia. Demographic characteristics, underlying disease and recent treatment, antifungal prophylaxis, neutropenia, receipt of corticosteroids, clinical and radiological findings, mycological results, antifungal therapy, and 6-week and 12-week survival were recorded. RESULTS: We identified 77 cases of IA in 54 patients with AML and 23 patients with ALL. The majority of patients developed IA in the context of induction chemotherapy for newly diagnosed (48.0%) or relapsed (41.6%) leukemia, with no differences between ALL and AML. Lung involvement was more frequent in AML (96.3% vs. 82.6%, p = 0.06) and rhinosinusitis was more common in ALL (43.5% vs. 24.1%, p = 0.09). Galactomannan was the microbiologic documentation of IA in 76.6%, with similar patterns of positivity in AML and ALL. The 6-week survival of IA in patients with AML and ALL was 63.0% and 56.5%, respectively (p = 0.60). CONCLUSIONS: The epidemiology, clinical presentation, diagnosis and outcome of IA in ALL patients are similar to patients with AML.

ERG11 Analysis among Clinical Isolates of Trichosporon asahii with Different Azole Susceptibility Profiles.

We analyzed a cohort of Trichosporon asahii strains with different MICs of fluconazole and voriconazole and evaluated the presence of ERG11 mutations. ERG11 mutation conferring an amino acid change was found and its resistance potential was evaluated by cloning into Saccharomyces cerevisiae susceptible host strain. Transformants were not resistant to either fluconazole nor voriconazole. Our results suggest that ERG11 variants exist among T. asahii isolates, but are not responsible for resistance phenotypes.

Quandaries of deciding when to change first-line therapy in invasive pulmonary aspergillosis.

We read the excellent viewpoint by Slavin et al. (J Antimicrob Chemother 2022; 77: 16-23) that draws upon the experience of an advisory board of notable experts to comprehensively address many of the clinical factors that drive the need for changes in antifungal therapy for invasive aspergillosis (IA). As noted by the authors, there remains a paucity of quality data to support many of the decisions faced by clinicians managing patients with IA. However, we would like to highlight several other important issues, not fully addressed in that viewpoint, that play an important role in deciding when to change antifungal therapy for IA.

The emerging threat antifungal-resistant Candida tropicalis in humans, animals, and environment.

Antifungal resistance in humans, animals, and the environment is an emerging problem. Among the different fungal species that can develop resistance, Candida tropicalis is ubiquitous and causes infections in animals and humans. In Asia and some Latin American countries, C. tropicalis is among the most common species related to candidemia, and mortality rates are usually above 40%. Fluconazole resistance is especially reported in Asian countries and clonal spread in humans and the environment has been investigated in some studies. In Brazil, high rates of azole resistance have been found in animals and the environment. Multidrug resistance is still rare, but recent reports of clinical multidrug-resistant isolates are worrisome. The molecular apparatus of antifungal resistance has been majorly investigated in clinical C. tropicalis isolates, revealing that this species can develop resistance through the conjunction of different adaptative mechanisms. In this review article, we summarize the main findings regarding antifungal resistance and Candida tropicalis through an "One Health" approach.

Nanopore Genome Sequencing and Variant Analysis of the Susceptible Candida auris Strain L1537/2020, Salvador, Brazil.

Candida auris has been reported worldwide, but only in December 2020, the first strain from a COVID-19 patient in Brazil was isolated. Here, we describe the genome sequence of this susceptible C. auris strain and performed variant analysis of the genetic relatedness with strains from other geographic localities.

Global guideline for the diagnosis and management of rare yeast infections: an initiative of the ECMM in cooperation with ISHAM and ASM.

Uncommon, or rare, yeast infections are on the rise given increasing numbers of patients who are immunocompromised or seriously ill. The major pathogens include those of the genera Geotrichum, Saprochaete, Magnusiomyces, and Trichosporon (ie, basidiomycetes) and Kodamaea, Malassezia, Pseudozyma (ie, now Moesziomyces or Dirkmeia), Rhodotorula, Saccharomyces, and Sporobolomyces (ie, ascomycetes). A considered approach to the complex, multidisciplinary management of infections that are caused by these pathogens is essential to optimising patient outcomes; however, management guidelines are either region-specific or require updating. In alignment with the One World-One Guideline initiative to incorporate regional differences, experts from diverse geographical regions analysed publications describing the epidemiology and management of the previously mentioned rare yeasts. This guideline summarises the consensus recommendations with regards to the diagnostic and therapeutic options for patients with these rare yeast infections, with the intent of providing practical assistance in clinical decision making. Because there is less clinical experience of patients with rare yeast infections and studies on these patients were not randomised, nor were groups compared, most recommendations are not robust in their validation but represent insights by use of expert opinions and in-vitro susceptibility results. In this Review, we report the key features of the epidemiology, diagnosis, antifungal susceptibility, and treatment outcomes of patients with Geotrichum, Saprochaete, Magnusiomyces, and Trichosporon spp infections.

Axillary Digital Thermometers uplifted a multidrug-susceptible Candida auris outbreak among COVID-19 patients in Brazil.

OBJECTIVES: To describe the first outbreak of Candida auris in Brazil, including epidemiological, clinical and microbiological data. METHODS: After the first Candida auris-colonised patient was diagnosed in a COVID-19 ICU at a hospital in Salvador, Brazil, a multidisciplinary team conducted a local C. auris prevalence investigation. Screening cultures for C. auris were collected from patients, healthcare workers and inanimate surfaces. Risk factors for C. auris colonisation were evaluated, and the fungemia episodes that occurred after the investigation were also analysed and described. Antifungal susceptibility of the C. auris isolates was determined, and they were genotyped with microsatellite analysis. RESULTS: Among body swabs collected from 47 patients, eight (n = 8/47, 17%) samples from the axillae were positive for C. auris. Among samples collected from inanimate surfaces, digital thermometers had the highest rate of positive cultures (n = 8/47, 17%). Antifungal susceptibility testing showed MICs of 0.5 to 1 mg/L for AMB, 0.03 to 0.06 mg/L for voriconazole, 2 to 4 mg/L for fluconazole and 0.03 to 0.06 mg/L for anidulafungin. Microsatellite analysis revealed that all C. auris isolates belong to the South Asian clade (Clade I) and had different genotypes. In multivariate analysis, having a colonised digital thermometer was the only independent risk factor associated with C. auris colonisation. Three episodes of C. auris fungemia occurred after the investigation, with 30-day attributable mortality of 33.3%. CONCLUSIONS: Emergence of C. auris in Salvador, Brazil, may be related to local C. auris clade I closely related genotypes. Contaminated axillary monitoring thermometers may facilitate the dissemination of C. auris reinforcing the concept that these reusable devices should be carefully cleaned with an effective disinfectant or replaced by other temperature monitoring methods.

Emergence of Candida auris in Brazil in a COVID-19 Intensive Care Unit.

In December 2020, Candida auris emerged in Brazil in the city of Salvador. The first two C. auris colonized patients were in the same COVID-19 intensive care unit. Antifungal susceptibility testing showed low minimal inhibitory concentrations of 1 µg/mL, 2 µg/mL, 0.03 µg/L, and 0.06 µg/mL for amphotericin B, fluconazole, voriconazole, and anidulafungin, respectively. Microsatellite typing revealed that the strains are clonal and belong to the South Asian clade C. auris. The travel restrictions during the COVID-19 pandemic and the absence of travel history among the colonized patients lead to the hypothesis that this species was introduced several months before the recognition of the first case and/or emerged locally in the coastline Salvador area.

Epidemiology, clinical aspects, outcomes and prognostic factors associated with Trichosporon fungaemia: results of an international multicentre study carried out at 23 medical centres.

BACKGROUND: Trichosporon fungaemia (TF) episodes have increased in recent years and mortality rates remain high despite the advances in the management of sepsis. New concepts about its clinical course, treatment and microbiology need to be investigated for the better management of this infection. OBJECTIVES: To describe the aetiology, natural history, clinical management and prognostic factors of TF. METHODS: TF episodes documented between 2005 and 2018 in 23 South American centres were retrospectively investigated by using a standard clinical form. Molecular identification, antifungal susceptibility testing and biofilm production were also performed. RESULTS: Eighty-eight TF episodes were studied. Patients had several underlying conditions, including haematological diseases (47.7%), post-operative status (34%), solid organ transplants (n = 7, 7.9%), among others. Seventy-three (82.9%) patients had a central venous catheter (CVC) at TF diagnosis. The 30 day mortality rate was 51.1%. Voriconazole-based therapy was given to 34 patients (38.6%), with a 30 day mortality rate of 38.2%. Multivariate predictors of 30 day mortality were age (OR 1.036), mechanical ventilation (OR 8.25) and persistent neutropenia (OR 9.299). CVC removal was associated with over 75% decreased risk of 30 day mortality (OR 0.241). Microbiological analyses revealed that 77.7% of the strains were identified as Trichosporon asahii, and voriconazole showed the strongest in vitro activity against Trichosporon spp. Most of the strains (63%) were considered medium or high biofilm producers. CONCLUSIONS: Older age, mechanical ventilation and persistent neutropenia were associated with poor prognosis. CVC may play a role in the pathogenicity of TF and its removal was associated with a better prognosis.

Trends towards lower azole susceptibility among 200 Candida tropicalis bloodstream isolates from Brazilian medical centres.

OBJECTIVES: Candida tropicalis is one of the three most frequent species causing candidaemia in Latin America. Despite the high prevalence of C. tropicalis in candidaemia cases in Brazil, little is known about the trends in fluconazole susceptibility over time. The objective of this study was to evaluate temporal trends in azole resistance rates among C. tropicalis bloodstream isolates from patients treated in six Brazilian medical centres over a 12-year period. METHODS: We selected 200 C. tropicalis bloodstream isolates from six medical centres in Brazil collected between 2007 and 2018. Species identification was confirmed by MALDI-TOF/MS. Antifungal susceptibility testing for four antifungal agents was performed by the Clinical and Laboratory Standards Institute (CLSI) microbroth method. RESULTS: Overall, rates of non-susceptibility were 4% and 3.5% to fluconazole and voriconazole, respectively. All isolates were susceptible to amphotericin B and only one isolate was resistant to echinocandins. CONCLUSION: Although we failed to demonstrate statistical differences in the rates of azole resistance documented during the period of analysis, trends towards lower susceptibility to fluconazole and voriconazole were shown.

Lack of relationship between genotype and virulence in Candida species / Ausencia de relación entre el genotipo y la virulencia en especies de Candida

BACKGROUND: The virulence of isolates among different Candida species causing candidemia may play a role in the prognosis of the patients. Furthermore, the potential relationship between genotype and virulence is still unclear and need to be further studied. AIMS: We aim to assess the relationship between genotype and virulence in Candida species using a Galleria mellonella larvae infection model. METHODS: One hundred and ninety-four isolates from 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) were compared against the same number of each species singleton genotypes in terms of survival of G. mellonella larvae. RESULTS: The median of survival and the IQR ranges of clusters and singleton were as follows: C. albicans (2 days, IQR 1.5-2 vs. 2 days, IQR 1-2.25), C. parapsilosis (2 days, IQR 1.5-2.6 vs. 2 days, IQR 2-3.3), and C. tropicalis (1 day, IQR 1-3.5 vs. 2 days, IQR 2-3.5; p < 0.05). High intra-cluster variability in terms of median of survival was found regardless the species. CONCLUSIONS: No relationship between genotype and virulence in Candida was observed with the G. mellonella model

ANTECEDENTES: La virulencia de cepas de diferentes especies de Candida causantes de candidemia puede jugar un papel en el pronóstico de los pacientes, y su estudio en el modelo de infección en Galleria mellonella puede ser útil para entender su contribución general a la infección. Además, la potencial relación entre genotipo y virulencia requiere de más estudios. OBJETIVOS: Se evaluó la relación entre genotipo y virulencia en especies de Candida mediante el modelo de infección de larvas de G. mellonella. MÉTODOS: Se estudió la supervivencia de las larvas infectadas con 194 aislados incluidos en 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) y con el mismo número de aislados con genotipos únicos por especie. RESULTADOS: La mediana de supervivencia y los rangos intercuartílicos (IQR) de clusters y genotipos únicos se muestra a continuación: C. albicans (2 días, IQR: 1,5-2 vs. 2 días, IQR: 1-2,25), C. parapsilosis (2 días, IQR: 1,5-2,6 vs. 2 días, IQR: 2-3,3), y C. tropicalis (un día, IQR: 1-3,5 vs. 2 días, IQR: 2-3,5; p < 0,05). Encontramos una importante variabilidad en la mediana de supervivencia entre cepas del mismo cluster, independientemente de la especie analizada. CONCLUSIONES: No se encontró relación entre el genotipo y la virulencia entre los aislados de Candida evaluados mediante el modelo de infección de G. mellonella

Do high MICs predict the outcome in invasive fusariosis?

BACKGROUND: Invasive fusariosis (IF) affects mostly severely immunocompromised hosts and is associated with poor outcome. Since Fusarium species exhibit high MICs for most antifungal agents, this could explain the poor prognosis. However, a clear-cut correlation between MIC and outcome has not been established. OBJECTIVE: To evaluate the correlation between MIC and outcome (6 week death rate) in patients with IF. METHODS: We performed a multicentre retrospective study of patients with IF who received treatment and had MIC levels determined by EUCAST or CLSI for the drug(s) used during treatment. We compared the MIC50 and MIC distribution among survivors and patients who died within 6 weeks from the diagnosis of IF. RESULTS: Among 88 patients with IF, 74 had haematological diseases. Primary treatment was monotherapy in 52 patients (voriconazole in 27) and combination therapy in 36 patients (liposomal amphotericin B + voriconazole in 23). The MIC50 and range for the five most frequent agents tested were: voriconazole 8 mg/L (range 0.5-64), amphotericin B 2 mg/L (range 0.25-64), posaconazole 16 mg/L (range 0.5-64), itraconazole 32 mg/L (range 4-64), and isavuconazole 32 mg/L (range 8-64). There was no difference in MIC50 and MIC distribution among survivors and patients who died. By contrast, persistent neutropenia and receipt of corticosteroids were strong predictors of 6 week mortality. CONCLUSIONS: Our study did not show any correlation between MIC and mortality at 6 weeks in patients with IF.

Lack of relationship between genotype and virulence in Candida species.

BACKGROUND: The virulence of isolates among different Candida species causing candidemia may play a role in the prognosis of the patients. Furthermore, the potential relationship between genotype and virulence is still unclear and need to be further studied. AIMS: We aim to assess the relationship between genotype and virulence in Candida species using a Galleria mellonella larvae infection model. METHODS: One hundred and ninety-four isolates from 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) were compared against the same number of each species singleton genotypes in terms of survival of G. mellonella larvae. RESULTS: The median of survival and the IQR ranges of clusters and singleton were as follows: C. albicans (2 days, IQR 1.5-2 vs. 2 days, IQR 1-2.25), C. parapsilosis (2 days, IQR 1.5-2.6 vs. 2 days, IQR 2-3.3), and C. tropicalis (1 day, IQR 1-3.5 vs. 2 days, IQR 2-3.5; p<0.05). High intra-cluster variability in terms of median of survival was found regardless the species. CONCLUSIONS: No relationship between genotype and virulence in Candida was observed with the G. mellonella model.

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.

Trichosporon asahii is an opportunistic fungal pathogen that can cause severe infections with high mortality rates. Azole derivatives are the best-targeted therapy for T. asahii invasive infections, but azole-resistant isolates have been reported. To investigate peculiarities in the antifungal susceptibility profile (ASP) of T. asahii clinical isolates, we analyzed the genotype distribution, isolation sources, and ASP of 284 strains collected from 1997 to 2019 in different Brazilian medical centers. Species identification and genotype characterization were performed by analysis of the intergenic spacer (IGS1) region of the ribosomal DNA (rDNA). Antifungal susceptibility testing (AST) for amphotericin B and azoles was with the CLSI M27, 4th edition, microdilution broth method. Trends in the ASP of Brazilian T. asahii isolates were investigated using epidemiological cutoff values. Five different genotypes were found among the 284 isolates tested (G1, 76%; G3, 10%; G4, 3%; G5, 7%; and G7, 4%). The isolates were collected mainly from urine (55%) and blood/catheter tip samples (25%) where G1 was the most frequent genotype found (P < 0.05). The G7 isolates exhibited the highest MIC90 values for azoles compared to those for the other genotypes (P < 0.05). Genotype 7 isolates also contributed to the increasing rates of voriconazole non-wild-type isolates found in recent years (P = 0.02). No significant differences were found among the AST results generated by isolates cultured from different anatomical sites. Monitoring T. asahii genotype distributions and antifungal susceptibility profiles is warranted to prevent the spread of azole-resistant isolates.

(1,3)-ß-D-glucan is able to predict therapeutic failure of patients with candidemia and not only mortality.

BACKGROUND: Candidemia is a major cause of bloodstream infection in tertiary hospitals worldwide and fungal biomarkers may provide early diagnosis. OBJECTIVES: To evaluate the performance of (1-3)-ß-D-glucan (BDG) in the diagnosis of candidemia and its ability to predict therapeutic failure. PATIENTS AND METHODS: This was a prospective, multi-centre study conducted in 3 Brazilian hospitals. Clinical outcome was evaluated along 2 weeks of treatment, and therapeutic failure was defined as the occurrence of persistent candidemia, Candida deep-seated infection or death. Baseline BDG detection was performed with the Fungitell® assay (Associates of Cape Cod, Falmouth-USA). RESULTS: We enrolled a total of 71 patients with candidemia and a control group with 110 healthy volunteers. The sensitivity and specificity of BDG for diagnosing candidemia were as follows: 71.8% (95% confidence interval [95% CI] 59.7% - 81.5%) and 98.2% (95% CI 92.9% - 99.7%), respectively. The only predictor of therapeutic failure was a higher BDG value at diagnosis of candidemia; a value > 226 pg/mL predicted failure with sensitivity and specificity of 75% and 78%, respectively. CONCLUSIONS: A high baseline serum BDG value was associated with therapeutic failure.