Comparison of fungemia caused by Candida and non-Candida rare yeasts: a retrospective study from a tertiary care hospital

Although Candida species are the most common cause of fungemia, non-Candida rare yeasts (NCY) have been increasingly reported worldwide. Although the importance of these yeast infections is recognized, current epidemiological information about these pathogens is limited, and they have variable antifungal susceptibility profiles. In this study, we aimed to evaluate the clinical characteristics for fungemia caused by NCY by comparing with candidemia. The episodes of NCY fungemia between January 2011 and August 2023 were retrospectively evaluated in terms of clinical characteristics, predisposing factor, and outcome. In addition, a candidemia group, including patients in the same period was conducted for comparison. Antifungal susceptibility tests were performed according to the reference method. A total of 85 patients with fungemia episodes were included: 25 with NCY fungemia and 60 with candidemia. Fluconazole had high minimal inhibitory concentration (MIC) values against almost all NCY isolates. The MIC values for voriconazole, posaconazole, and amphotericin B were ≤ 2 µg/ml, and for caspofungin and anidulafungin were ≥ 1 µg/ml against most of isolates. Hematological malignancies, immunosuppressive therapy, neutropenia and prolonged neutropenia, polymicrobial bacteremia/fungemia, preexposure to antifungal drugs, and breakthrough fungemia were associated with NCY fungemia, whereas intensive care unit admission, diabetes mellitus, urinary catheters, and total parenteral nutrition were associated with candidemia. In conclusion, the majority of fungemia due to NCY species was the problem, particularly in hematology units and patients with hematological malignancy. Preexposure to antifungal drugs likely causes a change in the epidemiology of fungemia in favor of non-albicans Candida and/or NCY.

Rare multi-fungal sepsis: a case of triple-impact immunoparalysis

Patients with burn injury and inhalation injury are highly susceptible to infectious complications, including opportunistic pathogens, due to the loss of skin cover and mucosal damage of respiratory tract as well as the disruption of homeostasis. This case report, a 34-year-old man suffered critical burns, provides the first literature description of triple-impact immunoparalysis (critical burns, inhalation injury, and SARS-CoV-2 infection), leading to a lethal multifocal infection caused by several fungi including very rare environmental representatives Metschnikowia pulcherrima and Wickerhamomyces anomalus. The co-infection by these common environmental yeasts in a human is unique and has not yet been described in the literature. Importantly, our patient developed refractory septic shock and died despite targeted antifungal therapy including the most potent current antifungal agent-isavuconazole. It can be assumed that besides immunoparalysis, effectiveness of therapy by isavuconazole was impaired by the large distribution volume in this case. As this is a common situation in intensive care patients, routine monitoring of plasmatic concentration of isavuconazole can be helpful in personalization of the treatment and dose optimization. Whatmore, many fungal species often remain underdiagnosed during infectious complications, which could be prevented by implementation of new methods, such as next-generation sequencing, into clinical practice.

Lodderomyces elongisporus as causative organism of oropharyngeal infections - Two case reports

We report two cases of patients with oropharyngeal infection by Lodderomyces elongisporus. The identification of the two isolates was confirmed after sequencing the ITS1 and ITS4 regions. The antifungal susceptibility test revealed low MIC values for the different antifungals tested. This is the first reported case of L. elongisporus present during an oropharyngeal infection and describes the laboratory methodology employed in the diagnosis.

Saprochaete/Magnusiomyces: identification, virulence factors, and antifungal susceptibility of a challenging rare yeast

Saprochaete/Magnusiomyces is among rare yeasts which might emerge as causes of breakthrough infections and nosocomial outbreaks. Identification to the species level might be a challenge in clinical laboratories. Data on virulence factors are scarce and antifungal susceptibility testing methodology is not definite. The aim of this study was to confirm species identification of clinical Saprochaete/Magnusiomyces isolates, find out their virulence factors, and obtain antifungal minimum inhibitory concentrations with two reference methods. Of the 57 isolates included, 54 were Saprochaete capitata and four were Saprochaete clavata as identified by ID32C, MALDI-TOF MS, and sequencing. When tested using phenotypic methods, all isolates were negative for coagulase, hemolysis, acid proteinase, and phospholipase, 56.1% were positive for esterase, and 19.3% had intermediate surface hydrophobicity. All isolates formed biofilms, with 40.4% of the isolates producing more biomass than biofilm-positive reference strain Candida albicans MYA-274. Antifungal susceptibility testing needed an adjusted spectrophotometric inoculum than recommended in reference methods for Candida/Cryptococcus. In conclusion, Saprochaete/Magnusiomyces species could be identified using methods available in the clinical laboratories. Despite the disadvantages of the phenotypic methods, esterase positivity was observed for the first time. A high biomass production was observed in biofilms. The need for standardization of antifungal susceptibility testing was brought to attention.

Neonatal fungemia caused by Lodderomyces elongisporus: first case report in Latin America

Premature hospitalized neonates have a greater risk for candidemia, however, fungemia due to rare opportunistic yeasts have been recently reported and is associated with high mortality rates. We herein report the first case in Latin America of Lodderomyces elongisporus fungemia in a premature neonate with a fatal outcome.

Seasonal Variation in Fungi in Beach Sand in Summertime: Stintino (Italy)

BACKGROUND

The goal of this study was to monitor the microbial biodiversity in beach sand that is heavily visited by tourists during the summer, and to determinate whether the high presence of bathers (around 5000 per day) can modify sand microbial composition.

METHODS

Between 2016 and 2020, 150 sand samples were collected from nine different points at La Pelosa beach in Sardinia, Italy. Non-culturing methods were used; DNA extraction and meta-barcode sequencing were performed. All samples were analyzed with sequencing methods for 16S and ITS sequences.

RESULTS

Fungal genera differ on the three beaches and in the winter/summer zones. The ITS sequence showed the most common presence of Candida during summer and Paradendryphiella in the winter. The greatest diversity was found in the dune during winter, while in other parts of the beach, there are differences between bacteria and fungi, particularly in the wash zone during the winter, with high diversity for 16S sequences but low diversity for ITS sequences.

CONCLUSIONS

It appears reasonable that the sands, even on non-urban beaches, should be included in health monitoring programs in addition to the waters, and that access to them should be regulated by limiting the number of bathers with the aim of reducing the presence of pathogenic fungal species.

Subacute infective endocarditis due to Lodderomyces elongisporus: a case report and review of the literature

Lodderomyces elongisporus, a rare emerging pathogen, can cause fungemia often related to immunosuppression or intravenous devices. Herein, we report the case of a 58-year-old woman with subacute infective endocarditis due to Lodderomyces elongisporus identified by blood fungal culture and whole-genome sequencing, who was treated with antifungals, mitral replacement and endocardial vegetation removal surgery.

Wickerhamomyces Anomalus Postoperative Endophthalmitis

INTRODUCTION

We describe the case of a postoperative fungal endophthalmitis caused by Wickerhamomyces anomalus, an opportunistic yeast common in nature but rare as a causative agent in ocular infections. This would be the second reported case of W. anomalus endophthalmitis.

CASE REPORT

A patient came to our hospital with a dense hemovitreous caused by an inadvertent ocular perforation and retinal detachment during a cataract surgery. In the days following the first vitreoretinal surgery a chronic postoperative endophthalmitis was evidenced. Only after several surgeries as well as intravitreal antibiotics and sample takings, Wickerhamomyces was detected. The treatment with oral voriconazole and an intraocular lens extraction controlled the infection.

DISCUSSION

Wickerhamomyces anomalus, despite not being particularly aggressive in our case, was resistant to various consequent vitreoretinal surgeries. The unresponsiveness to treatment led us to contemplate the fungal etiology, and fortunately the cultures were positive for this yeast. In conjunction to antifungal therapy, it is possible that the IOL explantation played an important role in the treatment.

CONCLUSION

A high index of suspicion must be held in cases of fungal endophthalmitis. Both IOL explantation and oral antifungal therapy are useful treatment options in cases of W. anomalus endophthalmitis.

The Epidemiology and Clinical Characteristics of Fungemia in a Tertiary Hospital in Southern China: A 6-Year Retrospective Study

Knowledge of the epidemiology and clinical characteristics of fungemia in southern China is limited. We conducted a six-year retrospective descriptive study to analyze the epidemiological and clinical characteristics of fungemia at the largest tertiary hospital in Guangxi, southern China. Data were obtained from the laboratory registry of patients with fungemia between January 2014 and December 2019. Demographic characteristics, underlying medical conditions, and outcomes for each case were analyzed. A total of 455 patients with fungemia were identified. Unexpectedly, Talaromyces marneffei (T. marneffei) was the most frequently isolated agent causing fungemia in the region (149/475, 31.4%), and Candida albicans (C. albicans) was the most commonly isolated Candida spp. (100/475, 21.1%). We identified that more than 70% of talaromycosis fungemia developed in AIDS patients, whereas candidemia was most commonly associated with a history of recent surgery. Notably, the total mortality rate of fungemia and the mortality rate in patients with T. marneffei and Cryptococcus neoformans (C. neoformans) fungemia were significantly higher in HIV-uninfected patients than in HIV-infected patients. In conclusion, the clinical pattern of fungemia in Guangxi is different from that in previous studies. Our study may provide new guidance for the early diagnosis and prompt treatment of fungemia in similar geographic regions.

Fungemia due to rare non-Candida yeasts between 2018 and 2021 in a Greek tertiary care university hospital

INTRODUCTION

Non-Candida yeasts, although rare, are increasingly encountered and recognized as a growing threat.

METHODS

Cases of bloodstream infections (BSIs) due to non-Candida yeasts (NCYs) during the last four years (2018-2021) are presented.

RESULTS

During the study period, 16 cases caused by non-Candida yeasts out of 400 cases of yeast BSIs were recorded, corresponding to an incidence of 4%. Yeasts that were isolated included Cryptococcus spp (4 isolates-25%), Rhodotorula mucilaginosa (2 isolates-12.5%), Trichosporon asahii (7 isolates-43.75%) and Saccharomyces cerevisiae (3 isolates-18.75%). Predisposing factors involved mostly hematological malignancies, long term hospitalization or major surgical interventions. Most isolates, 15 out of 16 were susceptible to amphotericin B. Voriconazole was the most active azole in vitro. All isolates, except Saccharomyces spp., were resistant to echinocandins.

DISCUSSION

Early recognition of rare yeasts as causative agents of BSIs and prompt initiation of appropriate treatment based on current guidelines and expertise remain crucial in efficient patient management.

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.

The first case of Wickerhamomyces anomalus fungemia in Iran in an immuneodeficient child, a review on the literature

The incidence of invasive candidiasis in pediatric patients is increasing and is associated with significant morbidity and mortality. C. pelliculosa has been rarely reported as a human pathogen, however, it has been associated with serious nosocomial infections and clonal outbreaks with poor clinical outcomes in immunocompromised children were reported. Here, we describe the first case of candidemia due to Candida pelliculosa in a 5-year-old immunocompromised male suffered from Griscelli syndrome with hemophagocytic syndrome hospitalized in the pediatric intensive care unit (PICU), Tehran, Iran. In addition, the history of reported cases or case-series due to C. pelliculosa is reviewed.

Gut-derived fungemia due to Kodamaea ohmeri combined with invasive pulmonary aspergillosis: a case report

BACKGROUND

Kodamaea ohmeri is a rare pathogen with high mortality and is found among blood samples in a considerable proportion; however, gastrointestinal infection of K. ohmeri is extremely rare. Invasive pulmonary aspergillosis is also an uncommon fungal; these two fungal infections reported concomitantly are unprecedented.

CASE PRESENTATION

We described a case of a 37-year-old male who got infected with K. ohmeri and invasive pulmonary aspergillosis. We used the mass spectrometry and histopathology to identify these two fungal infections separately. For the treatment of K. ohmeri, we chose caspofungin. As for invasive pulmonary aspergillosis, we used voriconazole, amphotericin B, and then surgery. The patient was treated successfully through the collaboration of multiple disciplines.

CONCLUSIONS

We speculate that the destruction of the intestinal mucosa barrier can make the intestine one of the ways for certain fungi to infect the human body.

Fatal Lodderomyces elongisporus Fungemia in a Premature, Extremely Low-Birth-Weight Neonate

Many rare yeasts are emerging as pathogens, causing invasive infections in susceptible hosts that are associated with poor clinical outcome. Here, we describe the first and fatal case of Lodderomyces elongisporus fungemia in a premature, extremely low-birth-weight neonate after spontaneous vaginal delivery. The bloodstream isolate was identified as C. parapsilosis by the VITEK 2 yeast identification system and as L. elongisporus by PCR-sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA. Antifungal susceptibility testing data for the isolate, performed by the broth microdilution-based MICRONAUT-AM assay, showed susceptibility to all nine antifungal drugs tested. Despite the initiation of treatment with liposomal amphotericin B, the patient died on the same day that the blood culture yielded yeast growth. This is the first report of L. elongisporus bloodstream infection in a neonate as the previous nine cases reported in the literature occurred in adult patients. The crude mortality rate for invasive L. elongisporus infection is 50%, as only 5 of 10 patients survived.

A Pragmatic Approach to Susceptibility Classification of Yeasts without EUCAST Clinical Breakpoints

EUCAST has established clinical breakpoints for the six most common Candida species and Cryptococcus neoformans but not for less common yeasts because sufficient evidence is lacking. Consequently, the question “How to interpret the MIC?” for other yeasts often arises. We propose a pragmatic classification for amphotericin B, anidulafungin, fluconazole, and voriconazole MICs against 30 different rare yeasts. This classification takes advantage of MIC data for more than 4000 isolates generated in the EUCAST Development Laboratory for Fungi validated by alignment to published EUCAST MIC data. The classification relies on the following two important assumptions: first, that when isolates are genetically related, pathogenicity and intrinsic susceptibility patterns may be similar; and second, that even if species are not phylogenetically related, the rare yeasts will likely respond to therapy, provided the MIC is comparable to that against wild-type isolates of more prevalent susceptible species because rare yeasts are most likely “rare” due to a lower pathogenicity. In addition, the treatment recommendations available in the current guidelines based on the in vivo efficacy data and clinical experience are taken into consideration. Needless to say, it is of utmost importance (a) to ascertain that the species identification is correct (using MALDI-TOF or sequencing), and (b) to re-test the isolate once or twice to confirm that the MIC is representative for the isolate (because of the inherent variability in MIC determinations). We hope this pragmatic guidance is helpful until evidence-based EUCAST breakpoints can be formally established.

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.

The Flo Adhesin Family

The first step in the infection of fungal pathogens in humans is the adhesion of the pathogen to host tissue cells or abiotic surfaces such as catheters and implants. One of the main players involved in this are the expressed cell wall adhesins. Here, we review the Flo adhesin family and their involvement in the adhesion of these yeasts during human infections. Firstly, we redefined the Flo adhesin family based on the domain architectures that are present in the Flo adhesins and their functions, and set up a new classification of Flo adhesins. Next, the structure, function, and adhesion mechanisms of the Flo adhesins whose structure has been solved are discussed in detail. Finally, we identified from Pfam database datamining yeasts that could express Flo adhesins and are encountered in human infections and their adhesin architectures. These yeasts are discussed in relation to their adhesion characteristics and involvement in infections.

Insight into the antifungals used to address human infection due to Trichosporon spp.: a scoping review

Trichosporonosis infections have been increasing worldwide. Providing adequate treatment for these infections remains a challenge. This scoping review contains information about potential antifungals to treat this pathology. Using online databases, we found 76 articles published between 2010 and 2020 related to this topic. Classic antifungals, molecules and biomolecules, repositioned drugs and natural products have been tested against species of Trichosporon. Experimental research has lacked depth or was limited to in vitro and in vivo tests, so there are no promising new candidates for the clinical treatment of patients with trichosporonosis. Furthermore, most studies did not present appropriate scientific criteria for drug tests, compromising their quality.

Kodamaea ohmeri as an Emerging Human Pathogen: A Review and Update

Background: Kodamaea ohmeri, previously known as Pichia ohmeri or Yamadazyma ohmeri, has been regarded as an emerging human pathogen in recent decades, and has caused various types of infections with high mortality. This study systematically reviewed all the published cases of K. ohmeri infection, aiming to have a better understanding of the clinical and epidemiological characteristics of the organism. Methods: All the published literature (as of March 31, 2021) on K. ohmeri, in four databases: PubMed, Embase, Web of Science, and CNKI, were systematically reviewed to select appropriate studies for summarizing the demographic information, clinical and microbiological characteristics of relevant infections. Results: A total of 51 studies involving 67 patients were included for final analysis, including 49 sporadic cases and two clusters of outbreaks. Neonates and the elderly constituted the majority of patients, and fungemia was the dominant infection type. Comorbidities (like malignancy, diabetes, and rheumatism), invasive operations, previous antibiotic use and prematurity, were commonly described in patients. Gene sequencing and broth microdilution method, were the most reliable way for the identification and antifungal susceptibility testing of K. ohmeri, respectively. Amphotericin B and fluconazole were the commonest antifungal therapies administered. The calculated mortality rates for K. ohmeri infection was higher than that of common candidemia. Conclusion: In this study, we systematically reviewed the epidemiology, clinical characteristics, microbiological features, treatment, and outcomes, of all the published cases on K. ohmeri. Early recognition and increased awareness of K. ohmeri as an emerging human pathogen by clinicians and microbiologists is important for effective management of this organism.

The first described case of Lodderomyces elongisporus meningitis

We describe the first documented case of meningitis caused by Lodderomyces elongisporus. Identification of L. elongisporus was made on the basis of an arachnoid biopsy with pathology samples sent for fungal internal transcribed spacer sequencing after multiple central nervous system (CNS) fungal culture specimens were negative. After final diagnosis, treatment was transitioned from amphotericin to fluconazole, which, combined with insertion of lumbar drain followed by a permanent ventriculopleural shunt, resulted in significant clinical improvement. Our report reviews the literature of (1) cases of L. elongisporus, which almost exclusively describe fungemia or endocarditis; (2) CNS infections caused by Candida parapsilosis, an organism with which L. elongisporus was previously conflated; and (3) management of fungal meningitis-associated hydrocephalus.

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.

A Survival Analysis of Invasive Fungal Diseases in Children with Cancer

Objective This study aimed to determine the survival in a retrospective cohort of 152 patients treated for invasive fungal diseases (IFD) (133 proven and 19 probable) in 9 years.

Methods Our study included patients aged 0 to 18 years diagnosed with cancer at our institution and with proven or probable IFD, treated from 2011 to 2019. Weibull distribution was used for hazard ratios and accelerated failure time models for the outcome “death attributed to IFD.”

Results Our median age was 97 months. The most frequent diagnosis was leukemia (39, 25.7%). A total of 37 patients received prophylaxis with fluconazole (24.3%). Among 133 fungal isolates, the most frequent were Candida species in blood 81 (53.2%). Moreover, 43 deaths were attributed to IFD (28.3%). Survival probabilities were lower for pulmonary IFD (46.9%, p = 0.0017), leukemia (62.5%, p = 0.004), and neutropenia <500 cells/mm3 (55.4%, p < 0.0001). For Candida fungemia, survival probabilities were 76.6% (p = 0.043). In Weibull models, the diagnosis of leukemia shortened survival times by a factor of 0.006, relapse of disease by 0.05, lymphoma by 0.04, pulmonary IFD by 0.04, and neutropenia by 0.015. Hematopoietic stem cell transplantation did not affect the survival times as well as prophylaxis with fluconazole.

Conclusion Host factors, such as neutropenia, relapse of disease, and hematologic malignancies, are determinants in the survival times of children with IFD as well as pulmonary involvement.

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.

Azole Susceptibility Profiles of More than 9,000 Clinical Yeast Isolates Belonging to 40 Common and Rare Species

Invasive yeast infections represent a major global public health issue, and only few antifungal agents are available. Azoles are one of the classes of antifungals used for treatment of invasive candidiasis. The determination of antifungal susceptibility profiles using standardized methods is important to identify resistant isolates and to uncover the potential emergence of intrinsically resistant species. Here, we report data on 9,319 clinical isolates belonging to 40 pathogenic yeast species recovered in France over 17 years. The antifungal susceptibility profiles were all determined at the National Reference Center for Invasive Mycoses and Antifungals based on the EUCAST broth microdilution method. The centralized collection and analysis allowed us to describe the trends of azole susceptibility of isolates belonging to common species, confirming the high susceptibility for Candida albicans (n = 3,295), Candida tropicalis (n = 641), and Candida parapsilosis (n = 820) and decreased susceptibility for Candida glabrata (n = 1,274) and Pichia kudriavzevii (n = 343). These profiles also provide interesting data concerning azole susceptibility of Cryptococcus neoformans species complex, showing comparable MIC distributions for the three species but lower MIC₅₀s and MIC₉₀s for serotype D (n = 208) compared to serotype A (n = 949) and AD hybrids (n = 177). Finally, these data provide useful information for rare and/or emerging species, such as Clavispora lusitaniae (n = 221), Saprochaete clavata (n = 184), Meyerozyma guilliermondii complex (n = 150), Candida haemulonii complex (n = 87), Rhodotorula mucilaginosa (n = 55), and Wickerhamomyces anomalus (n = 36).

Saprochaete clavata Infection in Immunosuppressed Patients: Systematic Review of Cases and Report of the First Oral Manifestation, Focusing on Differential Diagnosis

Background: Saprochaete clavata infection is an emerging issue in immunosuppressed patients, causing fulminant fungaemia. The purpose of this systematic review of cases is to retrieve all cases of S. clavata infection and describe oral lesions as the first manifestation of S. clavata infection. Methods: We report the first case of intraoral S. clavata infection in Acute Myeloid Leukemia (AML) affected subject, presenting as multiple grayish rapidly growing ulcerated swellings, and provide a review of all published cases of infection caused by S. clavata, according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, conducted by searching SCOPUS, Medline, and CENTRAL databases. Only articles in English were considered. Individual patient data were analyzed to identify risk factors for S. clavata infection. Results: Seventeen of 68 retrieved articles were included in the review reporting data on 96 patients (mean age 51.8 years, 57 males and 38 females). Most cases were disseminated (86) with a 60.2% mortality rate. Ninety-five were hematological patients, with AML being the most common (57 cases). Conclusions:S. clavata infection in immunosuppressed patients has a poor prognosis: middle-age patients, male gender and Acute Myeloid Leukemia should be considered risk factors. In immunosuppressed patients, the clinical presentation can be particularly unusual, imposing difficult differential diagnosis, as in the reported case.

Yeasts Associated with Various Amazonian Native Fruits

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.

Microbiological and virulence aspects of Rhodotorula mucilaginosa

We aimed to characterize microbiologically clinical isolates of R. mucilaginosa isolated from colonization of a patient with chronic renal disease (CKD), as well as to evaluate their phylogeny, antifungal susceptibility, virulence, and pathogenicity in order to infer the potential to become a possible infective agent. For this study, two isolates of R. mucilaginosa from oral colonization of a CKD patient were isolated, identified and characterized by classical (genotypic and phenotypic) methods. Susceptibility to conventional antifungals was evaluated, followed by biofilm production, measured by different techniques (total biomass, metabolic activity, colony forming units and extracellular matrix quantification). Finally, the pathogenicity of yeast was evaluated by infection of Tenebrio molitor larvae. All isolates were resistant to azole and sensitive to polyenes and they were able to adhere and form biofilm on the abiotic surface of polystyrene. In general, similar profiles among isolates were observed over the observed periods (2, 24, 48 and 72 hours). Regarding extracellular matrix components of biofilms at different maturation ages, R. mucilaginosa was able to produce eDNA, eRNA, proteins, and polysaccharides that varied according to time and the strain. The death curve in vivo model showed a large reduction in the survival percentage of the larvae was observed in the first 24 hours, with only 40 % survival at the end of the evaluation. We infer that colonization of chronic renal patients by R. mucilaginosa offers a high risk of serious infection. And also emphasize that the correct identification of yeast is the main means for an efficient treatment.

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.

Kodamaea ohmeri infections in humans: A systematic review

BACKGROUND

Kodamaea ohmeri, previously known as Pichia ohmeri or Yamadazyma ohmeri, belongs to the Saccharomycetaceae family and the Ascomycetae class, is the telomorphic form of C guilliermondii var. membranaefaciens and is frequently mistaken for Candida, as they belong to the same family. It has been isolated from environmental sources, such as sand, pools, seawater and fruits, while the last decades it is recognised as a rare pathogen that causes life-threatening infections in humans. The purpose of this study was to systemically review all published cases of K ohmeri infections in the literature and describe the epidemiology, microbiology, antimicrobial susceptibility, treatment and outcomes of these infections in humans.

METHODS

Systematic review of PubMed (through 27th December 2019) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of K ohmeri infections.

RESULTS

A total of 35 studies, containing data of 44 patients, were included in the analysis. The most common K ohmeri infections were those of the bloodstream, infective endocarditis and onychomycosis. Previous antibiotic use, presence of a central venous catheter, parenteral nutrition and cancer were very common among patients. Mortality was high in the case of fungemias but low for other types of infections. Amphotericin B and fluconazole are the most common agents used for treatment, even though alarming MICs for fluconazole were noted.

CONCLUSIONS

This systematic review thoroughly describes infections by K ohmeri and provides information on their epidemiology, clinical presentation, microbiology, antibiotic resistance patterns, treatment and outcomes.

Fungaemia due to rare yeasts in a tertiary care university centre within 18 years

BACKGROUND

Fungaemia due to rare yeasts has been recognised as an emerging, clinically relevant, but less investigated condition. Intrinsic resistance or reduced susceptibility of these species to echinocandins or fluconazole remains as a challenge in empirical treatment.

OBJECTIVES

To describe the clinical characteristics, administered antifungal agents, outcomes of patients with rare yeasts other than Candida (RY-OTC) fungaemia and determine the antifungal susceptibility profiles of the isolates.

PATIENTS AND METHODS

RY-OTC fungaemia between January-2001 and December-2018 were retrospectively evaluated. Antifungal susceptibility tests were performed according to CLSI M27-A3.

RESULTS

We identified 19 patients with fungaemia due to 20 RY-OTC (8 Trichosporon asahii, 4 Cryptococcus neoformans, 4 Saprochaete capitata, 3 Rhodotorula mucilaginosa, 1 Trichosporon mucoides) with an incidence of 2.2% among 859 fungaemia episodes. Haematological malignancy was the most common (42%) underlying disorder. In 6 patients, RY-OTC fungaemia developed as breakthrough infection while receiving echinocandins, amphotericin B or fluconazole. Amphotericin B, fluconazole or voriconazole were the drugs of choice for the initial treatment of breakthrough fungaemia. Among patients without previous exposure to antifungals, the most common empirical treatment was an echinocandin (50%), followed by fluconazole (42%) and amphotericin B (8%). Overall mortality was 47%. Worse outcome was most common among patients receiving echinocandins (83% vs 25%, P < .05). Voriconazole and posaconazole showed the highest in vitro activity against all the isolates tested. Amphotericin B MICs were relatively higher and the degree of activity of fluconazole and itraconazole was variable.

CONCLUSIONS

Early recognition of RY-OTC and knowledge about their susceptibility patterns remain crucial in initial treatment pending susceptibility data of isolates.

Elevated minimum inhibitory concentrations to antifungal drugs prevail in 14 rare species of candidemia-causing Saccharomycotina yeasts

Antifungal susceptibility profiles of rare Saccharomycotina yeasts remain missing, even though an increase in prevalence of such rare Candida species was reported in candidemia. Majority of these rare yeast species carry intrinsic resistances against at least one antifungal compound. Some species are known to be cross-resistant (against multiple drugs of the same drug class) or even multi-drug resistant (against multiple drugs of different drug classes). We performed antifungal susceptibility testing (AFST) according to EUCAST broth microdilution for 14 rare species (Clavispora lusitaniae, Candida intermedia, Candida auris, Diutina rugosa, Wickerhamiella pararugosa, Yarrowia lipolytica, Pichia norvegensis, Candida nivariensis, Kluyveromyces marxianus, Wickerhamomyces anomalus, Candida palmioleophila, Meyerozyma guilliermondii, Meyerozyma caribbica, and Debaryomyces hansenii) known to cause candidemia. In total, 234 isolates were tested for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, micafungin, and caspofungin. Amphothericin B had the broadest efficiency against the 14 tested rare yeast species, while high minimum inhibitory concentrations (MICs) against azole drugs and echinocandins were common. Voriconazole was the most efficient azole drug. Multidrug resistance was observed for the species C. auris and K. marxianus. Multidrug resistant individual isolates were found for Y. lipolytica and M. caribbica. In conclusion, the observed high MIC values of the rare Saccharomycotina species tested limit antifungal treatment options, complicating the management of such infections.

Scientific Opinion on the update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA (2017-2019)

The qualified presumption of safety (QPS) was developed to provide a safety pre-assessment within EFSA for microorganisms. Strains belonging to QPS taxonomic units (TUs) still require an assessment based on a specific data package, but QPS status facilitates fast track evaluation. QPS TUs are unambiguously defined biological agents assessed for the body of knowledge, their safety and their end use. Safety concerns are, where possible, to be confirmed at strain or product level, and reflected as 'qualifications'. Qualifications need to be evaluated at strain level by the respective EFSA units. The lowest QPS TU is the species level for bacteria, yeasts and protists/algae, and the family for viruses. The QPS concept is also applicable to genetically modified microorganisms used for production purposes if the recipient strain qualifies for the QPS status, and if the genetic modification does not indicate a concern. Based on the actual body of knowledge and/or an ambiguous taxonomic position, the following TUs were excluded from the QPS assessment: filamentous fungi, oomycetes, streptomycetes, Enterococcus faecium, Escherichia coli and bacteriophages. The list of QPS-recommended biological agents was reviewed and updated in the current opinion and therefore now becomes the valid list. For this update, reports on the safety of previously assessed microorganisms, including bacteria, yeasts and viruses (the latter only when used for plant protection purposes) were reviewed, following an Extensive Literature Search strategy. All TUs previously recommended for 2016 QPS list had their status reconfirmed as well as their qualifications. The TUs related to the new notifications received since the 2016 QPS opinion was periodically evaluated for QPS status in the Statements of the BIOHAZ Panel, and the QPS list was also periodically updated. In total, 14 new TUs received a QPS status between 2017 and 2019: three yeasts, eight bacteria and three algae/protists.

Unequivocal identification of an underestimated opportunistic yeast species, Cyberlindnera fabianii, and its close relatives using a dual-function PCR and literature review of published cases

Although Cyberlindnera fabinaii is a rare opportunist yeast species, its ability to cause septicemia, produce biofilm, and rapid acquisition of resistance to fluconazole and voriconazole, reinforced the urge for its identification from its closely related species. Widely used biochemical assays mainly identify Cyberlindnera fabinaii as Cyberlindnera jadinii and Wickerhamomyces anomalus, resulting in underestimation of this yeast in clinical settings. Moreover, the urge for a reliable molecular means of identification remains unsolved for 28 years. In order to unequivocally differentiate Cy. fabianii, Cy. mississipiensis, Cy. jadinii, and W. anomalus, we designed a dual-function multiplex polymerase chain reaction (PCR) assay. Challenging our dual-function multiplex PCR assay with 30 most clinically important yeast species, proved its specificity. Although conventional PCR could differentiate four target species, the real-time PCR counterpart due to Tm overlap misidentified Cy. mississipiensis as Cy. jadinii. Alongside of presenting a comprehensive literature review of published cases of Cy. fabianii from 1990 to 2018, we collected various clinical isolates from Tehran, Shiraz, and Fasa (July 1, 2017, to December 31, 2017) to find a passive relative distribution of these closely-related species in Iran. Subjecting our Iranian collection of yeast isolates to matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) MS and LSU and ITS rDNA sequencing revealed six isolates of Cy. fabianii (central venous catheter n = 2 and vaginal swabs n = 4) and one isolate of Cy. jadinii (vaginal swabs). Due to the use of biochemical assays in global ARTEMIS study, we encourage reidentification of clinical isolates of Cy. jadinii and Cy. jadinii using MALDI-TOF or Sanger sequencing that might lead to correcting the distribution of this fungus.

Necessity to identify candida species accurately with minimum inhibitory concentration determination in each case of bloodstream infections

BACKGROUND

Bloodstream Candida infection is a life-threatening event among ICU admitted patients. This infection is caused by a diverse range of Candida species having varied minimum inhibitory concentrations.

OBJECTIVES

To identify Candida species causing bloodstream infections with their antifungal susceptibility determination.

METHODS

Candida species isolated from the blood of ICU admitted patients were identified by phenotypic as well as by molecular methods including PCR-RFLP using MspI restriction enzyme and MALDI TOF MS. The minimum inhibitory concentration of fluconazole, voriconazole, amphotericin B and caspofungin was determined against isolated Candida species by CLSI M27A₃ guidelines.

RESULTS

A total of 119 Candida species were isolated. Among them, C. tropicalis(n=29) was the predominant isolate followed by C. parapsilosis(n=18), C. glabrata (n=12), C. krusei (n=11) and C. albicans(n=11). Uncommon Candida species isolated were; Wickerhamomyces anomalus(n=15), Kodaemia ohmeri(n=8), C. lusitaniae (n=5) and C. auris (n=2). A varied antifungal MIC values were observed. Caspofungin had the lowest MIC among the tested antifungals. Increased fluconazole MIC was observed against the isolated Candida species including C. tropicalis. All the isolated C. lusitaniae and C. auris strains have ≥1mcg/ml amphotericin B MIC. In comparison to fluconazole, voriconazole was more effective when tested in vitro.

CONCLUSION

Emergence of uncommon Candida species having varied antifungal MIC warns the physicians to have a prompt, accurate identification with antifungal MIC determination in each case of bloodstream Candida infections.

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.

Saprochaete clavata infections in patients undergoing treatment for haematological malignancies: A report of a monocentric outbreak and review of the literature

Saprochaete clavata is a rare cause of fungaemia with deep organ involvement in patients with haematological malignancies with reported mortality rates of 60%-80%. We describe four cases of S clavata infection in a haematology unit over several months that were treated with voriconazole-based regimens. We also review the literature on factors that could contribute to earlier recognition and effective treatment of S clavata. We included all cases of culture-positive S clavata from sterile sites with associated signs of infection in patients undergoing treatment for a haematological malignancy. Isolates were identified by MALDI-TOF MS, and spectrum profiles were used to prepare clustering analysis of isolates. Susceptibility testing was performed using a commercial microtitre methods. Saprochaete clavata was isolated from the bloodstream in three cases and bronchial alveolar lavage (BAL) fluid in one case. Clustering analysis suggested strains of S clavata were clonal without evidence of divergence although a common source was not identified. Susceptibility testing yielded elevated MICs to fluconazole (8 mg/L) and echinocandins (>1-8 mg/L). All patients were treated with voriconazole-based regimens resulting in survival of 3/4 patients, who continued chemotherapy for their underlying malignancy without evidence of relapse. Saprochaete clavata is a rare but aggressive cause of breakthrough yeast infection in patients undergoing treatment for haematological malignancies, particularly patients with a prior history of echinocandin treatment. Timely initiation of appropriate treatment, aided by more rapid identification in microbiology laboratory, can reduce the risk of deep organ dissemination and patient death.

Magnusiomyces capitatus fungemia: The value of direct microscopy in early diagnosis

Two cases of fungemia caused by Magnusiomyces capitatus, an arthroconidial yeast-like fungus, in non-hematologic immunocompromised patients are described. Both patients died before definite diagnosis of M. capitatus was made. The report highlights that pending confirmation of the isolate by phenotypic and/or molecular methods, the characteristic morphologic features observed in Gram-stained smears of blood culture positive bottles can lead to early preliminary diagnosis, thus significantly reducing time required for initiating appropriate antifungal therapy.

Multiple organ dysfunction syndrome and death secondary to Cyberlindnera fabianii

Cyberlindnera fabianii is a yeast present in soil rarely associated with invasive infection. Due to advanced diagnostic and therapeutic techniques, pathogenicity is increasingly recognized.

A 37-year-old male with B cell lymphoma on rituximab developed multiple organ dysfunction syndrome secondary to C. fabianii bacteremia. Specialized species identification techniques were required after failure of standard methods. Despite extracroporeal membrane oxygenation (ECMO) the patient died on day 26 after admission.

Identification and antifungal susceptibility profiles of Kodamaea ohmeri based on a seven-year multicenter surveillance study

Background

Kodamaea ohmeri has been a rare fungal pathogen in the past decades but is now becoming more common in various invasive fungal diseases, with high mortality. There are limited data on the occurrence and distribution of K. ohmeri.

Methods

Sixty-two K. ohmeri isolates collected from 24 hospitals in China over a 7-year period were studied. Performance of three phenotypic methods in the identification of this organism was assessed against a gold standard, 26S rDNA sequencing. Original identification results submitted by the participating local hospitals were reviewed. The Sensititre YeastOne YO10 (SYY) was evaluated in determining the in vitro antifungal susceptibilities using standard broth microdilution method (BMD) as a reference, and essential agreement (EA) was calculated.

Results

Accurate species identification was achieved in 82.3% and 96.8% of the cases by Vitek 2 Compact and Vitek mass spectrometry (MS), respectively. For Bruker MS, 12.9% and 96.8% of the isolates were correctly identified to species level using the direct transfer and protein extraction methods, respectively. Only 29 (46.8%) isolates were initially correctly identified as K. ohmeri by the local hospitals. The highest misidentification rate (100%, 16/16) was observed in CHROMagar. According to BMD, the highest MIC₉₀ was seen in fluconazole (8 μg/mL), followed by 1 μg/mL for micafungin, caspofungin, 5-fluorocytosine, and amphotericin B, 0.5 μg/mL for itraconazole, 0.25 μg/mL for posaconazole and voriconazole. Significant differences in EAs for different drugs were observed, ranging from 95.2% for amphotericin B to 22.6% for itraconazole between SYY and BMD.

Conclusion

Our study emphasizes the need for accurate identification of clinical K. ohmeri isolates and the importance of validating antifungal susceptibility by standard BMD.

Occurrence, antifungal susceptibility, and virulence factors of opportunistic yeasts isolated from Brazilian beaches

BACKGROUND

Opportunistic pathogenic yeast species are frequently associated with water habitats that have pollution sources of human or animal origin. Candida albicans has already been suggested as a faecal indicator microorganism for aquatic environments.

OBJECTIVES

The goal of this study was to investigate the occurrence of C. albicans and other opportunistic yeasts in sand and seawater samples from beaches in Brazil to assess their correlation with Escherichia coli, and to characterise the pathogenic potential of the yeast isolates.

METHODS

Opportunistic species (yeasts that grow at 37ºC) were isolated from sand and seawater samples from eight beaches in Brazil during the summer and the winter. Opportunistic yeast species were evaluated for their susceptibility to antifungal drugs, virulence factors, and the in vitro and in vivo biofilm formation. Strains were selected to carry out virulence tests using BALB/c mice.

FINDINGS

Several water samples could be classified as inappropriate for primary contact recreation in relation to E. coli densities. C. albicans was isolated in low densities. Of the 144 opportunistic yeasts evaluated, 61% displayed resistance or dose-dependent sensitivity to at least one tested drug, and 40% produced proteinase. Strains of C. albicans and Kodamaea ohmeri exhibited the highest rates of adhesion to buccal epithelial cells. All the C. albicans strains that were tested were able to undergo morphogenesis and form a biofilm on catheter fragments in both in vitro and in vivo experiments. It was possible to confirm the pathogenic potential of three of these strains during the disseminated infection test.

MAIN CONCLUSIONS

The identification of opportunistic yeast species in seawater and sand samples from Brazilian beaches suggest a potential risk to the health of people who use these environments for recreational purposes.

Yeasts isolated from tropical fruit ice creams: diversity, antifungal susceptibility and adherence to buccal epithelial cells

Abstract Fruit-based ice creams are products widely consumed in tropical countries and, because of their composition, can be a good source for microbial growth, including opportunistic pathogens. The aims of this study were to characterize the yeast populations present in Brazilian fruit-based ice creams, and to investigate the antifungal susceptibility to amphotericin B, fluconazole and itraconazole, and the ability of the isolates that were able to grow at 37 ºC to adhere to buccal epithelial cells (BEC). Two hundred and sixty-seven yeast isolates obtained from the ice cream samples were identified as belonging to 29 species, with counts that ranged from 1.5 to 5.2 log CFU/mL. The predominant species were Candida intermedia, Torulaspora delbrueckii, C. parapsilosis, Clavispora lusitaniae, Saccharomyces cerevisiae and Pichia kudriavzevii. At least 16 yeast species isolated in this study have been reported as opportunistic pathogens. Forty-one yeast isolates showed resistance or dose-dependent susceptibility to at least one of the antifungal drugs tested. One isolate of C. parapsilosis was resistant to all the antifungals tested and showed ability to adhere to BEC. The percentage of adhesion to BEC was high mainly for isolates of P. kudriavzevii, Meyerozyma guilliermondii, C. parapsilosis, S. cerevisiae and Debaromyces hansenii. The data suggest that the presence of these opportunistic yeasts as contaminants in ice creams may represent a potential risk to the final consumer, especially to immunocompromised individuals who may consume these products.

Genome sequence of the opportunistic human pathogen Magnusiomyces capitatus

The yeast Magnusiomyces capitatus is an opportunistic human pathogen causing rare yet severe infections, especially in patients with hematological malignancies. Here, we report the 20.2 megabase genome sequence of an environmental strain of this species as well as the genome sequences of eight additional isolates from human and animal sources providing an insight into intraspecies variation. The distribution of single-nucleotide variants is indicative of genetic recombination events, supporting evidence for sexual reproduction in this heterothallic yeast. Using RNAseq-aided annotation, we identified genes for 6518 proteins including several expanded families such as kexin proteases and Hsp70 molecular chaperones. Several of these families are potentially associated with the ability of M. capitatus to infect and colonize humans. For the purpose of comparative analysis, we also determined the genome sequence of a closely related yeast, Magnusiomyces ingens. The genome sequences of M. capitatus and M. ingens exhibit many distinct features and represent a basis for further comparative and functional studies.