FatalTrichosporonfungemia in patients with hematologic malignancies

Erythematous ulcero-proliferative exophytic lesion in an oral squamous cell carcinoma patient- An unusual case of Trichosporonosis

ABSTRACT

The emergence of non-Candida yeast infections in humans has been increasingly recognized over the last decades. Trichosporon is the third most isolated non-candidal yeast in patients with an impaired immune system. We report a rare case of Trichosporon asahii causing erythematous oral lesion in a patient with squamous cell carcinoma. Our case highlights the occurrence of unusual yeast pathogens in patients with cancer with typical clinical presentations and warrants suspicion of fungal etiology to prevent misdiagnosis of trichosporonosis.

Genetic analysis of emerging fungal pathogens: Trichosporon asahii

Trichosporon asahii is an emerging opportunistic fungus that mainly causes fatal disseminated trichosporonosis, especially in immunocompromised patients. T. asahii infection has been reported in Thailand, but few studies of this fungus have been published. Therefore, this study investigated the genetic diversity of 51 clinical strains of T. asahii from urine samples in Thailand. We sequenced and characterized the beta-1-tubulin (TUB1), copper-exporting ATPase (ATP), phosphate carrier protein (PHCP), and topoisomerase-1 (TOP1) genes. In addition, intergenic spacer 1 (IGS1) sequences from our previous studies were investigated. The numbers of haplotypes were 3, 3, 2, 2, and 2 for IGS1, TUB1, ATP, PHCP, and TOP1, respectively. The results suggested a relatively low level of genetic diversity among the strains. The findings illustrated that IGS1, TUB1, ATP, PHCP, and TOP1 can be collectively used as an alternative molecular typing tool for investigating the population diversity and structure of T. asahii.

Challenges in management of invasive fungal infections in stem cell transplant

Invasive fungal infections cause significant morbidity and mortality in hematopoietic stem cell transplant recipients. In order to minimize these infections, prophylaxis has become routine, although the agents used have changed over time. This presents new challenges as we consider an approach to breakthrough infections and recognize the epidemiologic shift toward isolates with higher rates of drug resistance. This review outlines the management of the most common pathogens (Candida, Aspergillus, Mucorales) as well as rarer pathogens that have higher rates of resistance (Trichosporon, Fusarium, Scedosporium, and Lomentospora). We discuss potential approaches to proven or possible breakthrough infections with yeast and pulmonary mold disease. Finally, we outline the role for combination therapy and newer antifungals, acknowledging current knowledge gaps and areas for future exploration.

Fungal Spectrum and Susceptibility Against Nine Antifungal Agents in 525 Deep Fungal Infected Cases

Background

Deep fungal infection has become an important cause of infection and death in hospitalized patients, and this has worsened with increasing antifungal drug resistance.

Objective

A 3-year retrospective study was conducted to investigate the clinical characteristics, pathogen spectrum, and drug resistance of deep fungal infection in a regional hospital of Guangzhou, China.

Methods

Non-duplicate fungi isolates recovered from blood and other sterile body fluids of in-patients of the clinical department were identified using biochemical tests of pure culture with the API20C AUX and CHROMagar medium. Antifungal susceptibilities were determined by Sensititre YeastOne^® panel trays.

Results

In this study, 525 patients (283 female, 242 male) with deep fungal infection were included, half of them were elderly patients (≥60 years) (54.67%, n=286). A total of 605 non-repetitive fungi were finally isolated from sterile samples, of which urine specimens accounted for 66.12% (n=400). Surgery, ICU, and internal medicine were the top three departments that fungi were frequently detected. The mainly isolated fungal species were Candida albicans (43.97%, n=266), Candida glabrata (20.00%, n=121), and Candida tropicalis (17.02%, n=103), which contributed to over 80% of fungal infection. The susceptibility of the Candida spp. to echinocandins, 5-fluorocytosine, and amphotericin B remained above 95%, while C. glabrata and C. tropicalis to itraconazole were about 95%, and the dose-dependent susceptibility of C. glabrata to fluconazole was more than 90%. The echinocandins had no antifungal activity against Trichosporon asahi in vitro (MIC₉₀>8 μg/mL), but azole drugs were good, especially voriconazole and itraconazole (MIC₉₀ = 0.25 μg/mL).

Conclusion

The main causative agents of fungal infection were still the genus of Candida. Echinocandins were the first choice for clinical therapy of Candida infection, followed with 5-fluorocytosine and amphotericin B. Azole antifungal agents should be used with caution in Candida glabrata and Candida tropicalis infections.

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.

Tacrolimus inhibits stress responses and hyphal formation via the calcineurin signaling pathway in Trichosporon asahii

The pathogenic fungus Trichosporon asahii causes fatal deep-seated mycosis in immunocompromised patients. Calcineurin, which is widely conserved in eukaryotes, regulates cell growth and various stress responses in fungi. Tacrolimus (FK506), a calcineurin inhibitor, induces sensitivity to compounds that cause stress on the cell membrane and cell wall integrity. In this study, we demonstrated that FK506 affects stress responses and hyphal formation in T. asahii. In silico structural analysis revealed that amino acid residues in the binding site of the calcineurin-FKBP12 complex that interact with FK506 are conserved in T. asahii. The growth of T. asahii was delayed by FK506 in the presence of SDS or Congo red but not in the presence of calcium chloride. FK506 also inhibited hyphal formation in T. asahii. A mutant deficient of the cnb gene, which encodes the regulatory subunit B of calcineurin, exhibited stress sensitivities on exposure to SDS and Congo red and reduced the hyphal forming ability of T. asahii. In the cnb-deficient mutant, FK506 did not increase the stress sensitivity or reduce hyphal forming ability. These results suggest that FK506 affects stress responses and hyphal formation in T. asahii via the calcineurin signaling pathway.

Circulating microbial content in myeloid malignancy patients is associated with disease subtypes and patient outcomes

Although recent work has described the microbiome in solid tumors, microbial content in hematological malignancies is not well-characterized. Here we analyze existing deep DNA sequence data from the blood and bone marrow of 1870 patients with myeloid malignancies, along with healthy controls, for bacterial, fungal, and viral content. After strict quality filtering, we find evidence for dysbiosis in disease cases, and distinct microbial signatures among disease subtypes. We also find that microbial content is associated with host gene mutations and with myeloblast cell percentages. In patients with low-risk myelodysplastic syndrome, we provide evidence that Epstein-Barr virus status refines risk stratification into more precise categories than the current standard. Motivated by these observations, we construct machine-learning classifiers that can discriminate among disease subtypes based solely on bacterial content. Our study highlights the association between the circulating microbiome and patient outcome, and its relationship with disease subtype.

Invasive Trichosporonosis in Neonates and Pediatric Patients with Malignancies or Hematologic Disorders

(1) Background: Trichosporon species have emerged as important opportunistic fungal pathogens, with Trichosporon asahii being the leading and most frequent cause of invasive disease. (2) Methods: We performed a global review focused on invasive trichosporonosis in neonates and pediatric patients with malignancies or hematologic disorders. We reviewed case reports and case series of trichosporonosis due to T. asahii published since 1994, the year of the revised taxonomic classification. (3) Results: Twenty-four cases of invasive trichosporonosis were identified in neonates with the presence of central venous catheter and use of broad-spectrum antibiotics recognized as the main predisposing factors. Thirty-two cases were identified in children with malignancies or hematologic disorders, predominantly with severe neutropenia. Trichosporon asahii was isolated from blood in 24/32 (75%) pediatric cases. Cutaneous involvement was frequently observed in invasive trichosporonosis. Micafungin was the most commonly used prophylactic agent (9/22; 41%). Ten patients receiving prophylactic echinocandins were identified with breakthrough infections. A favorable outcome was reported in 12/16 (75%) pediatric patients receiving targeted monotherapy with voriconazole or combined with liposomal amphotericin B. Overall mortality in neonates and children with malignancy was 67% and 60%, respectively. (4) Conclusions: Voriconazole is advocated for the treatment of invasive trichosporonosis given the intrinsic resistance to echinocandins and poor susceptibility to polyenes.

OUP accepted manuscript

Background

Invasive infections due to Trichosporon spp. are life-threatening opportunistic fungal infections that require complex clinical management. Guidelines assist clinicians but can be challenging to comply with.

Objectives

To develop a scoring tool to facilitate and quantify adherence to current guideline recommendations for invasive trichosporonosis.

Methods

We reviewed the current guideline for managing rare yeast infections (ECMM, ISHAM and ASM). The most important recommendations for diagnosis, treatment and follow-up were assembled and weighted according to their strength of recommendation and level of evidence. Additional items considered highly relevant for clinical management were also included.

Results

The resulting EQUAL Trichosporon Score 2022 comprises 18 items, with a maximum score of 39 points. For diagnostics, seven or eight items, depending on whether organ involvement is present or not, apply, resulting in a maximum of 18 or 21 points. Recommendations on diagnostics include imaging, infectious diseases expert consultation, culture, microscopy, molecular techniques, histopathology, and susceptibility testing. For treatment, six recommendations with a maximum of ten points were identified, with two additional points for organ involvement and one point for second-line treatment in uncontrolled disease. Treatment recommendations include immediate initiation, source control, pharmacological treatment, therapeutic drug monitoring, treatment duration and surgical intervention. Follow-up comprises two items with five points maximum, covering follow-up blood cultures and imaging.

Conclusions

The EQUAL Trichosporon Score weighs and aggregates factors recommended for optimal management of Trichosporon infections. It provides a tool for antifungal stewardship as well as for measuring guideline adherence, but remains to be correlated with patient outcomes.

Consensus guidelines for the diagnosis and management of cryptococcosis and rare yeast infections in the haematology/oncology setting, 2021

Cryptococcosis caused by the Cryptococcus neoformans-Cryptococcus gattii complex is an important opportunistic infection in people with immunodeficiency, including in the haematology/oncology setting. This may manifest clinically as cryptococcal meningitis or pulmonary cryptococcosis, or be detected incidentally by cryptococcal antigenemia, a positive sputum culture or radiological imaging. Non-Candida, non-Cryptococcus spp. rare yeast fungaemia are increasingly common in this population. These consensus guidelines aim to provide clinicians working in the Australian and New Zealand haematology/oncology setting with clear guiding principles and practical recommendations for the management of cryptococcosis, while also highlighting important and emerging rare yeast infections and their recommended management.

Strain Typing of Trichosporon asahii Clinical Isolates by Random Amplification of Polymorphic DNA (RAPD) Analysis

Objective The aim of this study was to identify and isolate Trichosporon asahii ( T. asahii ) from clinical samples and to assess the genetic relatedness of the most frequently isolated strains of T. asahii using random amplification of polymorphic DNA (RAPD) primers GAC-1 and M13.

Methods All the clinical samples that grew Trichosporon species, identified and confirmed by polymerase chain reaction (PCR) using Trichosporon genus-specific primers, were considered for the study. Confirmation of the species T. asahii was carried out by T. asahii- specific PCR. Fingerprinting of the most frequently isolated T. asahii isolates was carried out by RAPD using random primers GAC-1 and M13.

Results Among the 72 clinical isolates of Trichosporon sp. confirmed by Trichosporon -specific PCR, 65 were found to be T. asahii as identified by T. asahii- specific PCR. Fingerprinting of the 65 isolates confirmed as T. asahii using GAC-1 RAPD primer yielded 11 different patterns, whereas that of M13 primer produced only 5 patterns. The pattern I was found to be the most predominant type (29.2%) followed by pattern III (16.9%) by GAC-1 primer.

Conclusions This study being the first of its kind in India on strain typing of T. asahii isolates by adopting RAPD analysis throws light on genetic diversity among the T. asahii isolates from clinical samples. Fingerprinting by RAPD primer GAC-1 identified more heterogeneity among the T. asahii isolates than M13.

Comparison of the characteristics of patients with invasive infections and noninvasive infections caused by Trichosporon asahii

We performed retrospective study to identify the characteristics of invasive Trichosporon asahii infection. A total of 102 patients with T. asahii were identified including 18 (18%) with invasive infection. Invasive infection was associated with indwelling central venous catheter (94% vs 54%, P = .001), prior antifungal agent use (50% vs 18%, P = .01), hematologic malignancy (33% vs 7%, P = .006), and end-stage renal disease (28% vs 7%, P = .02). Patients with invasive infections had higher in-hospital mortality than patients with noninvasive infections (61% vs 27%, P = .006). Those with the above risk factors should be monitored for the development of invasive T. asahii infection.

LAY SUMMARY

Patients with indwelling central venous catheter, prior antifungal agent use, hematologic malignancy, and end-stage renal disease were associated with invasive Trichosporon asahii infection. Patients with invasive infections had higher in-hospital mortality than patients without invasive infection.

A Comprehensive Review of Trichosporon spp.: An Invasive and Emerging Fungus

Trichosporon species are basidiomycetous yeast-like organisms found ubiquitous in nature. They are increasingly been recognized as opportunistic pathogens capable of causing life-threatening invasive diseases (trichosporonosis), especially in immuno-suppressed patients and rarely in immuno-competent patients too. Earlier multiple members of the genus Trichosporon were clubbed together as T. beigelli but after the advent of molecular techniques, more than 50 different subspecies and around 16 different strains causing human diseases are reported. It is known to cause a wide range of diseases, from superficial to probable and proven invasive diseases to summer hypersensitivity. The ability of Trichosporon strains to form biofilms on implanted devices, glucuronoxylomannan in their cell walls, and production of proteases and lipases lead to the virulence of this genus. This ubiquitous fungus exhibits intrinsic resistance to echinocandins, variable minimum inhibitory concentrations (MIC) for amphotericin B, and moderate susceptibility to fluconazole and Itraconazole, which are the commonly used anti-fungal agents for any invasive fungal infections which lead to the re-emergence of this notorious yet neglected pathogen and hence the reports of breakthrough infections among patients receiving these antifungals. This review is to understand the epidemiological, clinical details, and antifungal susceptibility pattern of various Trichosporon infections and it highlights the importance of early detection and treatment for this emerging yeast and also will add to the ongoing surveillance for the anti-fungal susceptibility pattern for this fungus.

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.

Multidrug-resistant Trichosporon species: underestimated fungal pathogens posing imminent threats in clinical settings

Species of Trichosporon and related genera are widely used in biotechnology and, hence, many species have their genome sequenced. Importantly, yeasts of the genus Trichosporon have been increasingly identified as a cause of life-threatening invasive trichosporonosis (IT) in humans and are associated with an exceptionally high mortality rate. Trichosporon spp. are intrinsically resistant to frontline antifungal agents, which accounts for numerous reports of therapeutic failure when echinocandins are used to treat IT. Moreover, these fungi have low sensitivity to polyenes and azoles and, therefore, are potentially regarded as multidrug-resistant pathogens. However, despite the clinical importance of Trichosporon spp., our understanding of their antifungal resistance mechanisms is quite limited. Furthermore, antifungal susceptibility testing is not standardized, and there is a lack of interpretive epidemiological cut-off values for minimal inhibitory concentrations to distinguish non-wild type Trichosporon isolates. The route of infection remains obscure and detailed clinical and environmental studies are required to determine whether the Trichosporon infections are endogenous or exogenous in nature. Although our knowledge on effective IT treatments is rather limited and future randomized clinical trials are required to identify the best antifungal agent, the current paradigm advocates the use of voriconazole, removal of central venous catheters and recovery from neutropenia.

Emerging Fungal Infections

Various uncommon fungal pathogens have been increasingly identified as causes of disseminated and invasive fungal disease (IFD) worldwide. Growing recognition and clinical knowledge of these emerging fungal pathogens has occurred through improved molecular diagnostics, nucleic sequence databases, and taxonomic reclassification of medically significant fungi. However, emerging fungal diseases carry significant morbidity and mortality and, due to a paucity of published literature, the collective clinical experience with these fungi is often limited. In this review, we focus on unusual emerging fungal pathogens not extensively covered elsewhere in this issue of Infectious Diseases Clinics of North America.

Assessment of the Role of 1,3-β-d-Glucan Testing for the Diagnosis of Invasive Fungal Infections in Adults

Detection of 1,3-β-d-glucan (BDG) in serum has been evaluated for its inclusion as a mycological criterion of invasive fungal infections (IFI) according to EORTC and Mycoses Study Group (MSG) definitions. BDG testing may be useful for the diagnosis of both invasive aspergillosis and invasive candidiasis, when interpreted in conjunction with other clinical/radiological signs and microbiological markers of IFI. However, its performance and utility vary according to patient population (hematologic cancer patients, solid-organ transplant recipients, intensive care unit patients) and pretest likelihood of IFI. The objectives of this article are to provide a systematic review of the performance of BDG testing and to assess recommendations for its use and interpretation in different clinical settings.

Implication of efflux pumps and ERG11 genes in resistance of clinical Trichosporon asahii isolates to fluconazole

Introduction. Trichosporon asahii has been recognized as an opportunistic agent having a limited sensitivity to antifungal treatment.Hypothesis/Gap Statement. Molecular mechanisms of azole resistance have been rarely reported for Trichosproron asahii. Similar to other fungi, we hypothesized that both ERG11 gene mutation and efflux pumps genes hyper-expression were implicated.Aim. The current work aimed to study the sensitivity of clinical T. asahii isolates to different antifungal agents and to explore their resistance mechanisms by molecular methods including real-time PCR and gene sequencing.Methods. The sensitivity of T. asahii isolates to fluconazole, amphotericin B and voriconazole was estimated by the Etest method. Real-time PCR was used to measure the relative expression of Pdr11, Mdr and ERG11 genes via the ACT1 housekeeping gene. Three pairs of primers were also chosen to sequence the ERG11 gene. This exploration was followed by statistical study including the receiver operating characteristic (ROC) curve analysis to identify a relationship between gene mean expression and the sensitivity of isolates.Results. In 31 clinical isolates, the resistance frequencies were 87, 16.1 and 3.2 %, respectively, for amphotericin B, fluconazole and voriconazole. Quantitative real-time PCR demonstrated that only Mdr over-expression was significantly associated with FCZ resistance confirmed by univariate statistical study and the ROC curve analysis (P <0.05). The ERG11 sequencing revealed two mutations H380G and S381A in TN325U11 (MIC FCZ=8 µg ml^-1) and H437R in TN114U09 (MIC FCZ=256 µg ml^-1) in highly conserved regions (close to the haem-binding domain) but their involvement in the resistance mechanism has not yet been assigned.Conclusion. T. asahii FCZ resistance mechanisms are proven to be much more complex and gene alteration sequence and/or expression can be involved. Only Mdr gene over-expression was significantly associated with FCZ resistance and no good correlation was observed between FCZ and VCZ MIC values and relative gene expression. ERG11 sequence alteration seems to play a major role in T. asahii FCZ resistance mechanism but their involvement needs further confirmation.

Histopathological study on the prevalence of trichosporonosis in formalin-fixed and paraffin-embedded tissue autopsy sections by in situ hybridization with peptide nucleic acid probe

Trichosporon species are some of the most common pathogenic yeasts in Asia, and many are resistant to echinocandin antifungal drugs. Effective treatment of fungal infections requires the selection of appropriate antifungals and the accurate identification of the causal organism. However, in histopathological specimens Trichosporon spp. are often misidentified as Candida species due to morphological similarities. In situ hybridization (ISH) is a useful technique for identifying fungal species in formalin-fixed and paraffin-embedded (FFPE) tissue sections. Although many novel probes for ISH are available, the practical use of ISH for identification of fungi remains limited, in part due to the lack of adequate verifications. We conducted a two-center retrospective observational study in which the ISH technique was used to differentiate Trichosporon spp. and C. albicans in FFPE tissue from autopsy specimens. The study included 88 cases with blood stream yeast infection without Cryptococci extracted from 459 autopsy files of cases with proven invasive fungal infection (IFI). Positive signals for the Trichosporon spp. protein nucleic acid (PNA) probe and C. albicans PNA probe were seen for 7 and 35 cases, respectively, whereas the remaining 46 were negative for both. For the Trichosporon spp.- positive specimens, 5/7 were reported as candidiasis in autopsy records. Our results suggested that accurate histological identification of fungal infections remains challenging, but ISH may be a suitable approach to support histological findings. In addition, this retrospective study suggested that trichosporonosis may have high prevalence among cases of bloodstream yeast infections in Japan.

Successful Treatment of Breakthrough Trichosporon asahii Fungemia by the Combination Therapy of Fluconazole and Liposomal Amphotericin B in a Patient with Follicular Lymphoma

Invasive trichosporonosis is a rare and lethal fungal infection that occurs in immunocompromised patients. Breakthrough trichosporonosis can occur in patients treated with echinocandins since Trichosporon spp. are resistant to these antifungal agents. We report a case of breakthrough Trichosporon asahii fungemia. A 62-year-old Japanese woman with relapsed follicular lymphoma was treated empirically with broad-spectrum antibiotics and micafungin due to an intermittent fever during reinduction chemotherapy. After four cycles of anti-cancer chemotherapy, she experienced a high neutropenic fever and T. asahii was subsequently detected from a blood culture. The patient was not given voriconazole due to the contraindication for use with carbamazepine, and she was successfully treated with fluconazole plus liposomal amphotericin B without any serious complications. The combined therapy of fluconazole and liposomal amphotericin B may therefore be useful in treating T. asahii fungemia, especially in patients receiving antiepileptic agents.

A real-world prospective observational study on the efficacy and safety of liposomal amphotericin B in 426 patients with persistent neutropenia and fever

INTRODUCTION

Invasive fungal diseases are crucial causes of morbidity and mortality among patients with febrile neutropenia (FN). Though liposomal amphotericin B (L-AMB) is one of the agents recommended for first-line empirical antifungal therapy in patients with FN, large-scale clinical studies have not been performed in Japan.

METHODS

An open-label prospective multi-center study was carried out to evaluate the safety and efficacy of L-AMB in Japanese patients with FN suspected of having fungal infection.

RESULTS

Of the 426 patients registered, safety and efficacy evaluations were conducted for 424 and 399, respectively. By clinical response criteria using 5 composite endpoints, the response rate was 46.6% (186/399). The response rate by age were 54.5% (child: 30/55), 47.5% (adult: 97/204), 42.1% (elderly: 59/140) respectively. Regarding the composite endpoints, resolution of fever was observed in 61.2% (244/399), no breakthrough fungal infection in 99.0% (395/399), survival for 7 days or longer after the completion of treatment in 83.7% (334/399), no discontinuation of treatment due to toxicity or lack of efficacy in 60.9% (243/399), and successful treatment of any baseline fungal infection in 10/18. Adverse drug reactions (ADRs) developed in 61.1% (259/424), and frequent ADRs were hypokalemia, kidney dysfunction, and liver dysfunction, as previously reported.

CONCLUSIONS

The safety and efficacy profile of L-AMB in Japanese patients with FN suspected of having fungal infection were elucidated for the first time, through the analysis of a large number of cases including pediatric patients under real-world clinical settings collected in this nationwide study.

Role of arthroconidia in biofilm formation by Trichosporon asahii

BACKGROUND

Trichosporon asahii is the major causative agent of disseminated and deep-seated trichosporonosis. It is capable of forming biofilms on surfaces, leading to medical device-related infection.Trichosporon asahii may be present as yeast form, hyphae and/or arthroconidia; however, the relationship between its biofilm-forming ability and its morphological transition is unclear.

OBJECTIVES

We investigated whether the T. asahii morphological transition contributes to its biofilm formation. We also determined the conditions required to induce each of the morphologies.

METHODS

Three high- and three low-biofilm-producing strains (HBS and LBS, respectively) were selected using a biofilm formation assay, and the cell surface hydrophobicity of these six strains was measured. For each strain, the morphology was observed and the number of each morphological form (yeast form, hypha and arthroconidium) was counted to calculate the ratio. Finally, the ability of cells each morphological type to adhere to the polystyrene substrate was evaluated.

RESULTS

The HBS exhibited abundant arthroconidia and hyphae; in contrast, the LBS produced mainly hyphae with few or no arthroconidia. The production of hyphae was increased by nitrogen-containing medium, and the production of arthroconidia was increased by nitrogen-deficient medium. Cells incubated under nitrogen-deficient conditions showed higher adherence to a polystyrene surface than those incubated in the presence of nitrogen.

CONCLUSION

Arthroconidia of T. asahii play a key role in biofilm formation by promoting cellular adhesion.

Epidemiological study of Trichosporon asahii infections over the past 23 years

Trichosporon is a yeast-like basidiomycete, a conditional pathogenic fungus that is rare in the clinic but often causes fatal infections in immunocompromised individuals. Trichosporon asahii is the most common pathogenic fungus in this genus and the occurrence of infections has dramatically increased in recent years. Here, we report a systematic literature review detailing 140 cases of T. asahii infection reported during the past 23 years. Statistical analysis shows that T. asahii infections were most frequently reported within immunodeficient or immunocompromised patients commonly with blood diseases. Antibiotic use, invasive medical equipment and chemotherapy were the leading risk factors for acquiring infection. In vitro susceptibility, clinical information and prognosis analysis showed that voriconazole is the primary drug of choice in the treatment of T. asahii infection. Combination treatment with voriconazole and amphotericin B did not show superiority over either drug alone. Finally, we found that the types of infections prevalent in China are significantly different from those in other countries. These results provide detailed information and relevant clinical treatment strategies for the diagnosis and treatment of T. asahii infection.

Trichosporonosis Presenting as an Exophytic Cutaneous Mass Lesion

Opportunistic fungal pathogens have increased in frequency with the growing immunosuppressed population. New and emerging pathogens, including the rare yeasts, continue to cause significant morbidity and mortality and frequently develop despite prophylaxis with antifungal agents. We report a previously unreported manifestation of disseminated trichosporonosis. Our patient with underlying acute myeloid leukemia presented with as an exophytic toe lesion found secondary to Trichosporon asahii. We highlight the need for a high index of suspicion to diagnose breakthrough infections and the need for aggressive treatment.

An Overview of the Management of the Most Important Invasive Fungal Infections in Patients with Blood Malignancies

In patients with hematologic malignancies due to immune system disorders, especially persistent febrile neutropenia, invasive fungal infections (IFI) occur with high mortality. Aspergillosis, candidiasis, fusariosis, mucormycosis, cryptococcosis and trichosporonosis are the most important infections reported in patients with hematologic malignancies that undergo hematopoietic stem cell transplantation. These infections are caused by opportunistic fungal pathogens that do not cause severe issues in healthy individuals, but in patients with hematologic malignancies lead to disseminated infection with different clinical manifestations. Prophylaxis and creating a safe environment with proper filters and air pressure for patients to avoid contact with the pathogens in the surrounding environment can prevent IFI. Furthermore, due to the absence of specific symptoms in IFI, rapid and accurate diagnosis reduces the mortality rate of these infections and using molecular techniques along with standard mycological methods will improve the diagnosis of disseminated fungal infection in patients with hematologic disorders. Amphotericin B products, extended-spectrum azoles, and echinocandins are the essential drugs to control invasive fungal infections in patients with hematologic malignancies, and according to various conditions of patients, different results of treatment with these drugs have been reported in different studies. On the other hand, drug resistance in recent years has led to therapeutic failures and deaths in patients with blood malignancies, which indicates the need for antifungal susceptibility tests to use appropriate therapies. Life-threatening fungal infections have become more prevalent in patients with hematologic malignancies in recent years due to the emergence of new risk factors, new species, and increased drug resistance. Therefore, in this review, we discuss the different dimensions of the most critical invasive fungal infections in patients with hematologic malignancies and present a list of these infections with different clinical manifestations, treatment, and outcomes.

Treatment of invasive fungal diseases in cancer patients-Revised 2019 Recommendations of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

BACKGROUND

Invasive fungal diseases remain a major cause of morbidity and mortality in cancer patients undergoing intensive cytotoxic therapy. The choice of the most appropriate antifungal treatment (AFT) depends on the fungal species suspected or identified, the patient's risk factors (eg length and depth of granulocytopenia) and the expected side effects.

OBJECTIVES

Since the last edition of recommendations for 'Treatment of invasive fungal infections in cancer patients' of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) in 2013, treatment strategies were gradually moving away from solely empirical therapy of presumed or possible invasive fungal diseases (IFDs) towards pre-emptive therapy of probable IFD.

METHODS

The guideline was prepared by German clinical experts for infections in cancer patients in a stepwise consensus process. MEDLINE was systematically searched for English-language publications from January 1975 up to September 2019 using the key terms such as 'invasive fungal infection' and/or 'invasive fungal disease' and at least one of the following: antifungal agents, cancer, haematological malignancy, antifungal therapy, neutropenia, granulocytopenia, mycoses, aspergillosis, candidosis and mucormycosis.

RESULTS

AFT of IFDs in cancer patients may include not only antifungal agents but also non-pharmacologic treatment. In addition, the armamentarium of antifungals for treatment of IFDs has been broadened (eg licensing of isavuconazole). Additional antifungals are currently under investigation or in clinical trials.

CONCLUSIONS

Here, updated recommendations for the treatment of proven or probable IFDs are given. All recommendations including the levels of evidence are summarised in tables to give the reader rapid access to key information.

Make Sure You Have a Safety Net: Updates in the Prevention and Management of Infectious Complications in Stem Cell Transplant Recipients

Hematopoietic stem cell transplant recipients are at increased risk of infection and immune dysregulation due to reception of cytotoxic chemotherapy; development of graft versus host disease, which necessitates treatment with immunosuppressive medications; and placement of invasive catheters. The prevention and management of infections in these vulnerable hosts is of utmost importance and a key “safety net” in stem cell transplantation. In this review, we provide updates on the prevention and management of CMV infection; invasive fungal infections; bacterial infections; Clostridium difficile infection; and EBV, HHV-6, adenovirus and BK infections. We discuss novel drugs, such as letermovir, isavuconazole, meropenem-vaborbactam and bezlotoxumab; weigh the pros and cons of using fluoroquinolone prophylaxis during neutropenia after stem cell transplantation; and provide updates on important viral infections after hematopoietic stem cell transplant (HSCT). Optimizing the prevention and management of infectious diseases by using the best available evidence will contribute to better outcomes for stem cell transplant recipients, and provide the best possible “safety net” for these immunocompromised hosts.

N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, a zinc chelator, inhibits biofilm and hyphal formation in Trichosporon asahii

Objective

Trichosporon asahii is the major causative fungus of disseminated or deep-seated trichosporonosis and forms a biofilm on medical devices. Biofilm formation leads to antifungal drug resistance, so biofilm-related infections are relatively difficult to treat and infected devices often require surgical removal. Therefore, prevention of biofilm formation is important in clinical settings. In this study, to identify metal cations that affect biofilm formation, we evaluated the effects of cation chelators on biofilm formation in T. asahii.

Results

We evaluated the effect of cation chelators on biofilm formation, since microorganisms must assimilate essential nutrients from their hosts to form and maintain biofilms. The inhibition by N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) was greater than those by other cation chelators, such as deferoxamine, triethylenetetramine, and ethylenediaminetetraacetic acid. The inhibitory effect of TPEN was suppressed by the addition of zinc. TPEN also inhibited T. asahii hyphal formation, which is related to biofilm formation, and the inhibition was suppressed by the addition of zinc. These results suggest that zinc is essential for biofilm formation and hyphal formation. Thus, zinc chelators have the potential to be developed into a new treatment for biofilm-related infection caused by T. asahii.

Fatal Disseminated Infection by Trichosporon asahii Under Voriconazole Therapy in a Patient with Acute Myeloid Leukemia: A Review of Breakthrough Infections by Trichosporon spp

INTRODUCTION

Cases of invasive Trichosporon infections have increasingly emerged; it is now the second leading cause of yeast bloodstream infections after Candida spp., particularly in the immunosuppressed population, where it often causes breakthrough fungemia with high mortality.

METHODS

We present a case report of a breakthrough Trichosporon asahii infection in a patient with acute myeloid leukemia and review all of the cases of breakthrough Trichosporon spp. infections published in the literature to date.

RESULTS

We extracted 68 cases of breakthrough Trichosporon spp. infections, wherein 95.5% patients had hematological malignancy, 61.8% of them occurred in the presence of echinocandins, 22% of triazoles, 13.2% of amphotericin and 3% of other combinations of antifungals. The most prevalent manifestation was fungemia (94%); 82.8% of these were associated with the presence of a central venous catheter. The overall mortality was 68.7%; the patients who survived recovered from the neutropenic event.

CONCLUSIONS

Invasive trichosporonosis is an acute fatal condition that occurs in immunosuppressed patients, usually under antifungal selective pressure. Typically, neutropenia and its underlying diseases are associated with adverse outcomes.

Epidemiology and Antifungal Susceptibility of Infections Caused by Trichosporon Species: An Emerging Non-Candida and Non-Cryptococcus Yeast Worldwide

Introduction

Over the past four decades, there has been an increase in the number of fatal opportunistic invasive trichosporonosis cases especially in immunocompromised hosts.

Objective

The objective of the study is to evaluate the epidemiological, clinical details and antifungal susceptibility pattern of the patients with Trichosporon infections.

Materials and Methods

Twenty-four clinical isolates of Trichosporon species isolated from blood, samples, pleural fluid and nail were included in this study, over a period of 12 years (2005-2016) in a tertiary hospital in North India. The isolates were characterised phenotypically and few representative isolates were sequenced also. The minimum inhibitory concentration (MIC) was determined as per Clinical and Laboratory Standards Institute, 2012.

Results

Trichosporon spp. from blood culture (57.78%), nail (37.5%) and pleural fluid (4.17%). On phenotypic tests, 79.16% of the isolates were Trichosporon asahii, followed by Trichosporon dermatis (8.33%), Trichosporon japonicum (4.17%), Trichosporon ovoides (4.17%) and Trichosporon mucoides (4.17%). The MIC range of Trichosporon species from invasive infections were fluconazole (0.06-256 μg/ml), amphotericin B (0.125-16 μg/ml), voriconazole (0.0616-8 μg/ml), posaconazole (0.0616-32 μg/ml) and caspofungin (8-32 μg/ml). The isolates from superficial infection were resistant to fluconazole (0.06-256 μg/ml) and itraconazole (0.125-32 μg/ml), all were susceptible to ketoconazole and while only two were resistant to voriconazole (0.25-4 μg/ml).

Conclusion

T. asahii was the most common isolate. Disseminated trichosporonosis is being increasingly reported worldwide including India and represents a challenge for both diagnosis and species identification. Prognosis is limited, and antifungal regimens containing triazoles appear to be the best therapeutic approach. In addition, accurate identification, removal of central venous lines and voriconazole-based treatment along with control of underlying conditions were associated with favourable outcomes.

Exploring the resistance mechanisms in Trichosporon asahii: Triazoles as the last defense for invasive trichosporonosis

Trichosporon asahii has recently been recognized as an emergent fungal pathogen able to cause invasive infections in neutropenic cancer patients as well as in critically ill patients submitted to invasive medical procedures and broad-spectrum antibiotic therapy. T. asahii is the main pathogen associated with invasive trichosporonosis worldwide. Treatment of patients with invasive trichosporonosis remains a controversial issue, but triazoles are mentioned by most authors as the best first-line antifungal therapy. There is mounting evidence supporting the claim that fluconazole (FLC) resistance in T. asahii is emerging worldwide. Since 2000, 15 publications involving large collections of T. asahii isolates described non-wild type isolates for FLC and/or voriconazole. However, very few papers have addressed the epidemiology and molecular mechanism of antifungal resistance in Trichosporon spp. Data available suggest that continuous exposure to azoles can induce mutations in the ERG11 gene, resulting in resistance to this class of antifungal drugs. A recent report characterizing T. asahii azole-resistant strains found several genes differentially expressed and highly mutated, including genes related to the Target of Rapamycin (TOR) pathway, indicating that evolutionary modifications on this pathway induced by FLC stress may be involved in developing azole resistance. Finally, we provided new data suggesting that hyperactive efflux pumps may play a role as drug transporters in FLC resistant T. asahii strains.

Apiotrichum veenhuisii isolated from a pediatric patient with acute myeloid leukemia: The first case in humans

This is the first report of the yeast Apiotrichum veenhuisii (formerly Trichosporon veenhuisii) causing disease in humans; its virulence and in vitro behavior against antifungals were also studied. The sample was isolated from biopsy fragments of disseminated lesions on the skin of a pediatric patient with acute myeloid leukemia. The studied virulence factors evidenced that the strain tested negative for secretion of the enzymes proteinase, phospholipase, and hemolysin. The isolate was characterized as low biofilm producer. Except for amphotericin B and voriconazole, the sample presented high minimum inhibitory concentration values against azole and echinocandins.

In vivo pathogenicity of Trichosporon asahii isolates with different in vitro enzymatic profiles in an immunocompetent murine model of systemic trichosporonosis

Trichosporon asahii is an opportunistic yeastlike fungus that colonizes the gastrointestinal and respiratory tracts and human skin. Although it is an important cause of disseminated infections by non-Candida species, there are a few reports related to its virulence factors and their possible role in in vivo pathogenicity. We developed a murine model of disseminated trichosporonosis in immunocompetent mice for the evaluation of the in vivo pathogenicity of 6 T. asahii isolates with different in vitro virulence factor profiles. Tissue fungal burden was determined on days 1, 3, 7, 15, and 25 post-challenge. Overall, the largest fungal load was detected in the kidney on the 5 experimental days, while brain, spleen, and liver displayed a comparatively low fungal count. We observed a fungal burden decrease in most experimental groups from day 15. Histological analysis showed the presence of T. asahii in tissue and a generalized inflammatory infiltrate of polymorphonuclear cells in the kidney, liver, red pulp of the spleen, and the hippocampus. Even though our isolates showed different in vitro virulence factors profiles, we did not detect relevant differences when assayed in vivo, except for a higher persistence of a protease- and biofilm-producing strain in kidney, liver, and brain.

Isavuconazole for treatment of rare invasive fungal diseases

Data regarding treatment of rare invasive fungal diseases (IFDs) are scarce. We documented the efficacy and safety of isavuconazole for treatment of uncommonly diagnosed IFDs. VITAL was a single-arm, international, open-label study evaluating the efficacy and safety of isavuconazole (200 mg orally or intravenously every 8 hours for 48 hours, then once daily). The primary outcome was overall response at Day 42; key secondary outcomes were overall responses at Day 84 and end of treatment (EOT), mortality at Days 42 and 84, and safety. This analysis includes patients with IFD caused by rare or unidentified pathogens. Twenty-six patients with IFDs caused by rare moulds (n = 17), non-Candida yeasts (n = 2), or unidentified moulds (n = 7) were enrolled (median treatment duration [range], 114.5 [1-496]) days. Overall treatment success was observed in 11/26 (42.3%), 10/26 (38.5%), and 15/26 (57.7%) patients at Days 42, 84, and EOT, respectively. All-cause mortality rates were 2/26 patients (7.7%) at Day 42 and 4/26 patients (15.4%) at Day 84; another two patients died after Day 84. All patients had ≥1 treatment-emergent adverse event (TEAE); 15 patients (57.7%) had serious TEAEs, and TEAEs led to discontinuation of isavuconazole in four patients (15.4%). Isavuconazole may be efficacious for treatment of a range of rare IFDs.

Deep cutaneous Trichosporon asahii infection in a patient recovering from toxic epidermal necrolysis

Patients with toxic epidermal necrolysis, a condition that causes full thickness epidermal necrosis that affects over 30% of the skin surface and mucosal membranes, often develop comorbid infections throughout the recovery of the disease [1]. While most commonly these are related to a bacterial source, infections due to viral, mycobacterial, and rarely fungal organisms occur. We present a case of a patient who developed a deep cutaneous fungal infection caused by Trichosporon asahii and discuss the management.

Trichosporon loubieri Fungemia in a 39-Year-Old Caucasian Woman With B-Cell Lymphoblastic Leukemia

We report a case of Trichosporon loubieri (T. loubieri) fungemia with likely liver involvement in a 39-year-old Caucasian patient with relapsed B-cell acute lymphoblastic leukemia after an allogeneic hematopoietic cell transplant. This is the fifth published case of T. loubieri infection and only the third case of T. loubieri fungemia, to our knowledge. All 3 cases of T. loubieri infection with fungemia had liver involvement.

Catheter-Related Trichosporon asahii Bloodstream Infection in a Neutropenic Patient with Myelodysplastic Syndrome

Because primary antifungal prophylaxis is widely used for immunocompromised hosts, the incidences of unusual fungal infections have increased. Trichosporon asahii has emerged as an important life-threatening opportunistic systemic pathogen because of the increased use of cytotoxic or immunosuppressant agents, along with high mortality rates. Here, we describe a case of catheter-related T. asahii bloodstream infection with multiple septic skin nodules in both the arms and legs of the patient who was in the neutropenic period after allogeneic stem cell transplantation for myelodysplastic syndrome treated with prophylactic ciprofloxacin and itraconazole. We successfully treated her with intravenous voriconazole for more than a month without any complications. Clinicians should consider breakthrough Trichosporon infections when clinical progress in an immunocompromised patient with unexplained infection signs and symptoms does not improve despite proper treatment with antibiotics or various antifungal agents. In addition, voriconazole can be a good treatment choice for achieving better treatment results and prognosis.

Performance of VITEK mass spectrometry V3.0 for rapid identification of clinical Aspergillus fumigatus in different culture conditions based on ribosomal proteins

Fast and accurate discrimination of Aspergillus fumigatus is significant, since misidentification may lead to inappropriate clinical therapy. This study assessed VITEK mass spectrometry (MS) V3.0 for A. fumigatus identification using extracted fungal ribosomal proteins. A total of 52 isolates preliminarily identified as A. fumigatus by traditional morphological methods were inoculated in three different culture media and cultured at two different temperatures. The specific spectral fingerprints of different culture time points (48, 72, 96, and 120 h) were obtained. Of all strains, 88.5% (46/52) were discriminated as A. fumigatus, while the remaining 11.5% (6/52) produced results inconsistent with morphological analysis. Molecular sequencing, as a reference method for species identification, was used to validate the morphological analysis and matrix-assisted laser desorption/ionization time of flight MS. Chi-square tests (χ² test, P=0.05) demonstrated that the culture medium and incubation temperature had no effects on identification accuracy; however, identification accuracy of the strains in the 48-h group was lower than that in other groups. In addition, we found that ribosomal proteins extracted from A. fumigatus can be stored in different environments for at least 1 week, with their profiles remaining stable and strain identification results showing no change. This is beneficial for medical institutions with no mass spectrometer at hand. Overall, this study showed the powerful ability of VITEK MS V 3.0 in identifying A. fumigatus.

Successful treatment of breakthrough disseminated Trichosporon asahii fungemia in a patient with acute myeloid leukemia receiving itraconazole prophylaxis

We encountered a case of a 73-year-old man with acute myeloid leukemia who developed Trichosporon asahii systemic infection while on itraconazole prophylaxis during severe neutropenia. Cryptococcal antigen was useful for diagnosis. Although itraconazole was ineffective in protecting against trichosporonosis, treatment was successful with voriconazole following liposomal amphotericin B.

Yeasts

Yeasts are unicellular organisms that reproduce mostly by budding and less often by fission. Most medically important yeasts originate from Ascomycota or Basidiomycota. Here, we review taxonomy, epidemiology, disease spectrum, antifungal drug susceptibility patterns of medically important yeast, laboratory diagnosis, and diagnostic strategies.

The Cell Biology of the Trichosporon-Host Interaction

Fungi of the genus Trichosporon are increasingly recognized as causative agents of superficial and invasive fungal disease in humans. Although most species are considered commensals of the human skin and gastrointestinal tract, these basidiomycetes are an increasing cause of fungal disease among immunocompromised hosts, such as hematological patients and solid organ transplant recipients. The initiation of commensal or pathogenic programs by Trichosporon spp. involves the adaptation to the host microenvironment and its immune system. However, the exact virulence factors activated upon the transition to a pathogenic lifestyle, including the intricate biology of the cell wall, and how these interact with and subvert the host immune responses remain largely unknown. Here, we revisit our current understanding of the virulence attributes of Trichosporon spp., particularly T. asahii, and their interaction with the host immune system, and accommodate this knowledge within novel perspectives on fungal diagnostics and therapeutics.