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

Candida spp. isolated from recreational coastal waters of Rio de Janeiro - Brazil: Focus on antifungal resistance and virulence attributes

The use of recreational waters is a widespread activity worldwide, and one of the risks associated with this practice is the exposure of bathers to microorganisms that may arise due to pollution caused by inadequate infrastructure and sanitation. In the present work, we isolated Candida spp. (n = 24) from five recreational beaches in Rio de Janeiro, Brazil, in order to evaluate their susceptibility to antifungals, the production of virulence attributes and the in vivo virulence using Tenebrio molitor larvae as a model. The ITS1-5.8S-ITS2 gene sequencing identified thirteen isolates (54.1 %) as C. tropicalis, seven (29.1 %) as C. krusei (Pichia kudriavzevii), one (4.2 %) as C. rugosa (Diutina rugosa), one (4.2 %) as C. mesorugosa (Diutina mesorugosa), one (4.2 %) as C. utilis (Cyberlindnera jadinii) and one (4.2 %) as C. parapsilosis. C. tropicalis isolates showed resistance to azoles and susceptibility to amphotericin B, flucytosine and caspofungin. C. krusei isolates were resistant to fluconazole, caspofungin and itraconazole, with 42.8 % resistance to flucytosine, besides susceptibility to voriconazole and amphotericin B. The remaining species were susceptible to all tested antifungals. All Candida isolates adhered to abiotic surfaces and formed biofilm on polystyrene, albeit to varying degrees, and produced aspartic protease and hemolytic activity, which are considered fungal virulence attributes. C. tropicalis, C. krusei and C. utilis isolates produced phytase, while the only esterase producer was C. tropicalis. Regarding resistance to osmotic stress, all isolates of C. tropicalis, C. parapsilosis and C. mesorugosa grew up to 7.5 % NaCl; the remaining isolates grew up to 1.87-3.75 % NaCl. The mortality caused by fungal challenges in T. molitor larvae was variable, with C. tropicalis, C. utilis and C. parapsilosis being more virulent than C. krusei and C. rugosa complex. Collectively, the presence of these yeasts, particularly the virulent and resistant isolates, in recreational waters can pose a significant health risk to bathers.

What are the 100 most cited fungal genera?

The global diversity of fungi has been estimated between 2 to 11 million species, of which only about 155 000 have been named. Most fungi are invisible to the unaided eye, but they represent a major component of biodiversity on our planet, and play essential ecological roles, supporting life as we know it. Although approximately 20 000 fungal genera are presently recognised, the ecology of most remains undetermined. Despite all this diversity, the mycological community actively researches some fungal genera more commonly than others. This poses an interesting question: why have some fungal genera impacted mycology and related fields more than others? To address this issue, we conducted a bibliometric analysis to identify the top 100 most cited fungal genera. A thorough database search of the Web of Science, Google Scholar, and PubMed was performed to establish which genera are most cited. The most cited 10 genera are Saccharomyces, Candida, Aspergillus, Fusarium, Penicillium, Trichoderma, Botrytis, Pichia, Cryptococcus and Alternaria. Case studies are presented for the 100 most cited genera with general background, notes on their ecology and economic significance and important research advances. This paper provides a historic overview of scientific research of these genera and the prospect for further research. Citation: Bhunjun CS, Chen YJ, Phukhamsakda C, Boekhout T, Groenewald JZ, McKenzie EHC, Francisco EC, Frisvad JC, Groenewald M, Hurdeal VG, Luangsa-ard J, Perrone G, Visagie CM, Bai FY, Błaszkowski J, Braun U, de Souza FA, de Queiroz MB, Dutta AK, Gonkhom D, Goto BT, Guarnaccia V, Hagen F, Houbraken J, Lachance MA, Li JJ, Luo KY, Magurno F, Mongkolsamrit S, Robert V, Roy N, Tibpromma S, Wanasinghe DN, Wang DQ, Wei DP, Zhao CL, Aiphuk W, Ajayi-Oyetunde O, Arantes TD, Araujo JC, Begerow D, Bakhshi M, Barbosa RN, Behrens FH, Bensch K, Bezerra JDP, Bilański P, Bradley CA, Bubner B, Burgess TI, Buyck B, Čadež N, Cai L, Calaça FJS, Campbell LJ, Chaverri P, Chen YY, Chethana KWT, Coetzee B, Costa MM, Chen Q, Custódio FA, Dai YC, Damm U, de Azevedo Santiago ALCM, De Miccolis Angelini RM, Dijksterhuis J, Dissanayake AJ, Doilom M, Dong W, Alvarez-Duarte E, Fischer M, Gajanayake AJ, Gené J, Gomdola D, Gomes AAM, Hausner G, He MQ, Hou L, Iturrieta-González I, Jami F, Jankowiak R, Jayawardena RS, Kandemir H, Kiss L, Kobmoo N, Kowalski T, Landi L, Lin CG, Liu JK, Liu XB, Loizides M, Luangharn T, Maharachchikumbura SSN, Makhathini Mkhwanazi GJ, Manawasinghe IS, Marin-Felix Y, McTaggart AR, Moreau PA, Morozova OV, Mostert L, Osiewacz HD, Pem D, Phookamsak R, Pollastro S, Pordel A, Poyntner C, Phillips AJL, Phonemany M, Promputtha I, Rathnayaka AR, Rodrigues AM, Romanazzi G, Rothmann L, Salgado-Salazar C, Sandoval-Denis M, Saupe SJ, Scholler M, Scott P, Shivas RG, Silar P, Souza-Motta CM, Silva-Filho AGS, Spies CFJ, Stchigel AM, Sterflinger K, Summerbell RC, Svetasheva TY, Takamatsu S, Theelen B, Theodoro RC, Thines M, Thongklang N, Torres R, Turchetti B, van den Brule T, Wang XW, Wartchow F, Welti S, Wijesinghe SN, Wu F, Xu R, Yang ZL, Yilmaz N, Yurkov A, Zhao L, Zhao RL, Zhou N, Hyde KD, Crous PW (2024). What are the 100 most cited fungal genera? Studies in Mycology 108: 1-411. doi: 10.3114/sim.2024.108.01.

Isolation and identification of Wickerhamiella tropicalis from blood culture by MALDI-MS

Wickerhamiella is a genus of budding yeast that is mainly isolated from environmental samples, and 40 species have been detected. The yeast isolated from human clinical samples usually only contain three species: W. infanticola, W. pararugosa and W. sorbophila. In this study, we isolated W. tropicalis from a blood sample of a six-year-old female with a history of B-cell precursor lymphoblastic leukemia in Japan in 2022. Though the strain was morphologically identified as Candida species by routine microbiological examinations, it was subsequently identified as W. tropicalis by sequencing the internal transcribed spacer (ITS) of ribosomal DNA (rDNA). The isolate had amino acid substitutions in ERG11 and FKS1 associated with azole and echinocandin resistance, respectively, in Candida species and showed intermediate-resistant to fluconazole and micafungin. The patient was successfully treated with micafungin. Furthermore, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) detected three novel peaks that are specific for W. tropicalis, indicating that MALDI-MS analysis is useful for rapid detection of Wickerhamiella species in routine microbiological examinations.

Kodamaea ohmeri Leg Skin Ulcer Infection in an Immunocompetent Patient: A Case Report

INTRODUCTION

Kodamaea ohmeri is an emerging fungus recognised as an important pathogen in immunocompromised hosts, responsible for life-threatening infections.

CASE PRESENTATION

We describe a case of a 69-year-old immunocompetent man with a long history of leg skin ulcers infected by K. ohmeri. This is the first case of leg wounds infected by K. ohmeri in an immunocompetent patient. The infection was successfully treated with voriconazole 200 mg daily.

CONCLUSION

Though rare, K. ohmeri should be considered in patients with skin ulcers that are poorly responsive to medical treatment, even if not immunocompromised.

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.

Characterization of the Pathogenic Potential of the Beach Sand Microbiome and Assessment of Quicklime as a Remediation Tool

Beach sand may act as a reservoir for potential human pathogens, posing a public health risk. Despite this, the microbiological monitoring of sand microbiome is rarely performed to determine beach quality. In this study, the sand microbial population of a Northern Adriatic Sea beach sand was profiled by microbiological (CFU counts) and molecular methods (WGS, microarray), showing significant presence of potential human pathogens including drug-resistant strains. Consistent with these results, the potential of quicklime as a restoring method was tested in vitro and on-field. Collected data showed that adding 1-3% quicklime (w/w) to sand provided an up to -99% of bacteria, fungi, and viruses, in a dose- and time-dependent manner, till 45 days post-treatment. In conclusion, data suggest that accurate monitoring of sand microbiome may be essential, besides water, to assess beach quality and safety. Moreover, first evidences of quicklime potential for sand decontamination are provided, suggesting its usage as a possible way to restore the microbiological quality of sand in highly contaminated areas.

Glucose-enhanced oxidative stress resistance-A protective anticipatory response that enhances the fitness of Candida albicans during systemic infection

Most microbes have developed responses that protect them against stresses relevant to their niches. Some that inhabit reasonably predictable environments have evolved anticipatory responses that protect against impending stresses that are likely to be encountered in their niches-termed "adaptive prediction". Unlike yeasts such as Saccharomyces cerevisiae, Kluyveromyces lactis and Yarrowia lipolytica and other pathogenic Candida species we examined, the major fungal pathogen of humans, Candida albicans, activates an oxidative stress response following exposure to physiological glucose levels before an oxidative stress is even encountered. Why? Using competition assays with isogenic barcoded strains, we show that "glucose-enhanced oxidative stress resistance" phenotype enhances the fitness of C. albicans during neutrophil attack and during systemic infection in mice. This anticipatory response is dependent on glucose signalling rather than glucose metabolism. Our analysis of C. albicans signalling mutants reveals that the phenotype is not dependent on the sugar receptor repressor pathway, but is modulated by the glucose repression pathway and down-regulated by the cyclic AMP-protein kinase A pathway. Changes in catalase or glutathione levels do not correlate with the phenotype, but resistance to hydrogen peroxide is dependent on glucose-enhanced trehalose accumulation. The data suggest that the evolution of this anticipatory response has involved the recruitment of conserved signalling pathways and downstream cellular responses, and that this phenotype protects C. albicans from innate immune killing, thereby promoting the fitness of C. albicans in host niches.

Preclinical safety evaluation of Lipase OF from Candida cylindracea

Triacylglycerol lipases are enzymes commonly used to process foods and beverages such as oils, wines, and cheeses through catalyzation of long-chain triglyceride hydrolysis. Lipase OF derived from Candida cylindracea (strain MS-5-OF) is only intended for use as a processing aid in food production applications; however, it may be present at trace levels in some products. As such, the safety of Lipase OF was evaluated in this study that included a bacterial reverse mutation assay, an in vitro chromosome aberration test, and a 90-day subchronic toxicity study in rats. In the in vitro bacterial reverse mutation and chromosome aberration assays, Lipase OF was not observed to be mutagenic at concentrations up to 5000 μg/plate and 50 μg/ml, respectively, in the presence or absence of metabolic activation. Results from the 90-day subchronic toxicity study indicated only minimal adverse effects (i.e., increased platelet count and prothrombin time) in male rats from the high-dose group following administration of Lipase OF via the diet at levels of 0, 1.0, 2.5, and 5.0 w/w%. The no-observed-adverse-effect level (NOAEL) for Lipase OF was therefore considered 2.5 w/w% (1597.6 mg/kg body weight/day [1027.3 mg TOS/kg body weight/day]) in males and 5.0 w/w% (3700.4 mg/kg body weight/day [2379.4 mg TOS/kg body weight/day]) in females under the test conditions. Thus, the evidence presented within this study supports the safe use of Lipase OF as a processing aid in various food production applications for human consumption.

Occurrence, Diversity and Anti-Fungal Resistance of Fungi in Sand of an Urban Beach in Slovenia—Environmental Monitoring with Possible Health Risk Implications

Beach safety regulation is based on faecal indicators in water, leaving out sand and fungi, whose presence in both matrices has often been reported. To study the abundance, diversity and possible fluctuations of mycobiota, fungi from sand and seawater were isolated from the Portorož beach (Slovenia) during a 1-year period. Sand analyses yielded 64 species of 43 genera, whereas seawater samples yielded 29 species of 18 genera. Environmental and taxonomical data of fungal communities were analysed using machine learning approaches. Changes in the air and water temperature, sunshine hours, humidity and precipitation, air pressure and wind speed appeared to affect mycobiota. The core genera Aphanoascus, Aspergillus, Fusarium, Bisifusarium, Penicillium, Talaromyces, and Rhizopus were found to compose a stable community within sand, although their presence and abundance fluctuated along with weather changes. Aspergillus spp. were the most abundant and thus tested against nine antimycotics using Sensititre Yeast One kit. Aspergillus niger and A. welwitschiae isolates were found to be resistant to amphotericin B. Additionally, four possible human pollution indicators were isolated during the bathing season, including Meyerozyma, which can be used in beach microbial regulation. Our findings provide the foundations for additional research on sand and seawater mycobiota and show the potential effect of global warming and extreme weather events on fungi in sand and sea.

Candida species contamination in drinking groundwater from residence wells in three municipalities of midwestern Brazil and the potential human health risks

Groundwater represents one of the largest safe drinking water sources worldwide; however, it has been threatened by increased human activities in recent years. Candida species express virulence factors that contribute to the establishment and worsening of infections, although little is known about the virulence profiles of these species in potable groundwater. The aim of this study was to detect the presence of yeasts in groundwater from residential wells and to evaluate the antifungal susceptibility profile, hydrolytic enzyme production, adhesion capacity, and biofilm formation of Candida spp. Fifty yeasts representing nine genera were isolated: Candida (48%), Meyerozyma (20%), Pichia (8%), Exophiala (8%), Clavispora (4%), Kodamaea (4%), Rhodotorula (4%), Hanseniaspora (2%), and Kazachstania (2%). Candida parapsilosis was the most commonly isolated species, and approximately 29% of the Candida isolates were resistant to at least one azole. All Candida isolates were able to produce hydrolytic enzymes and adhere to polystyrene, and most were classified as hydrophobic. Candida spp. can establish and form biofilms when cultivated in different media such as Sabouraud broth, water, and calcium hypochlorite. The use of contaminated groundwater for human consumption represents a possible route for the transmission of clinically relevant yeasts that can cause fungal infections, especially in immunocompromised individuals. Therefore, it is important to evaluate and establish effective measures for groundwater treatment to ensure the quality and safety for consumption.

Collateral consequences of agricultural fungicides on pathogenic yeasts: A One Health perspective to tackle azole resistance

Candida and Cryptococcus affect millions of people yearly, being responsible for a wide array of clinical presentations, including life-threatening diseases. Interestingly, most human pathogenic yeasts are not restricted to the clinical setting, as they are also ubiquitous in the environment. Recent studies raise concern regarding the potential impact of agricultural use of azoles on resistance to medical antifungals in yeasts, as previously outlined with Aspergillus fumigatus. Thus, we undertook a narrative review of the literature and provide lines of evidence suggesting that an alternative, environmental route of azole resistance, may develop in pathogenic yeasts, in addition to patient route. However, it warrants sound evidence to support that pathogenic yeasts cross border between plants, animals and humans and that environmental reservoirs may contribute to azole resistance in Candida or other yeasts for humans. As these possibilities could concern public health, we propose a road map for future studies under the One Health perspective.

Extensive Diversity and Prevalent Fluconazole Resistance among Environmental Yeasts from Tropical China

Yeasts play important roles in both the environment and in human welfare. While some environmental yeasts positively contribute to nutrient cycling and food production, a significant number of yeast species are opportunistic human pathogens, including several that are tolerant/resistant to commonly used antifungal drugs. At present, most of our understanding of environmental yeasts has come from a few terrestrial environments in selected geographic regions. Relatively little is known about yeast diversity in tropical environments and their potential impacts on human health. Here, we characterize culturable yeasts in 968 environmental samples from eight regions in tropical China. Among the 516 soil, 273 freshwater, and 179 seawater samples, 71.5%, 85.7%, and 43.6% contained yeasts, respectively. A total of 984 yeast isolates were analyzed for their DNA barcode sequences and their susceptibilities to fluconazole. DNA sequence comparisons revealed that the 984 yeast isolates likely belonged to 144 species, including 106 known species and 38 putative novel species. About 38% of the 984 isolates belonged to known human pathogens and the most common species was Candida tropicalis, accounting for 21% (207/984) of all isolates. Further analyses based on multi-locus sequence typing revealed that some of these environmental C. tropicalis shared identical genotypes with clinical isolates previously reported from tropical China and elsewhere. Importantly, 374 of the 984 (38%) yeast isolates showed intermediate susceptibility or resistance to fluconazole. Our results suggest that these environmental yeasts could have significant negative impacts on human health.

Performance of Meyerozyma caribbica as a novel manganese peroxidase-producing yeast inhabiting wood-feeding termite gut symbionts for azo dye decolorization and detoxification

For hazardous toxic pollutants such as textile wastewater and azo dyes, microbial-based and peroxidase-assisted remediation represents a highly promising and environmentally friendly alternative. Under this scope, gut symbionts of the wood-feeding termites Coptotermes formosanus and Reticulitermes chinenesis were used for the screening of manganese peroxidase (MnP) producing yeasts intended for decolorization and detoxification of textile azo dyes, such as Acid Orange 7 (AO7). To this end, nine out of 38 yeast isolates exhibited high levels of extracellular MnP activity ranging from 23 to 27 U/mL. The isolate PPY-27, which had the highest MnP activity, was able to decolorize various azo dyes with an efficiency ranging from 87.2 to 98.8%. This isolate, which represents the molecularly identified species Meyerozyma caribbica, was successfully characterized in terms of morphological and physiological traits, as well as enzymatic activities. Almost complete decolorization was achieved by the MnP-producing M. caribbica strain SSA1654 after 6 h of incubation with 50 mg/L of the sulfonated azo dye AO7 at 28 °C with an agitation speed of 150 rpm. The maximum decolorization efficiency of AO7 reached 93.8% at 400 mg/L. The decolorization of AO7 was confirmed by Fourier transform infrared (FTIR) and UV-Vis spectral analysis. High performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) were used to identify AO7 decomposition intermediates. Based on UV-Vis spectra, FTIR, HPLC, and GC-MS analyses, a plausible AO7 biodegradation mechanism pathway was explored, showing azo bond (-N=N-) cleavage and toxic aromatic amines mineralization CO₂ and H₂O. Microtox® and phytotoxicity assays confirmed that the AO7 metabolites produced by the strain SSA1654 were almost non-toxic compared to the original sulfonated azo dye.

Wickerhamiella martinezcruziae f. a., sp. nov., a yeast species isolated from tropical habitats

Four yeast isolates with an affinity to the genus Wickerhamiella were obtained from beach sand, a marine zoanthid and a tree exudate at different localities in Brazil. Two other isolates with almost identical ITS and D1/D2 sequences of the large subunit rRNA gene were isolated from the small intestine of cattle and a grease trap in Thailand. These isolates represent a novel species phylogenetically related to Wickerhamiella verensis, Wickerhamiella osmotolerans, Wickerhamiella tropicalis, Wickerhamiella sorbophila and Wickerhamiella infanticola. The novel species differs by 15-30 nucleotide differences from these species in the D1/D2 sequences. The name Wickerhamiella martinezcruziae f.a., sp. nov. is proposed. The holotype of Wickerhamiella martinezcruziae sp. nov. is CBS 16104^T. The MycoBank number is MB 839328.

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

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

Mycosands: Fungal diversity and abundance in beach sand and recreational waters - Relevance to human health

The goal of most studies published on sand contaminants is to gather and discuss knowledge to avoid faecal contamination of water by run-offs and tide-retractions. Other life forms in the sand, however, are seldom studied but always pointed out as relevant. The Mycosands initiative was created to generate data on fungi in beach sands and waters, of both coastal and freshwater inland bathing sites. A team of medical mycologists and water quality specialists explored the sand culturable mycobiota of 91 bathing sites, and water of 67 of these, spanning from the Atlantic to the Eastern Mediterranean coasts, including the Italian lakes and the Adriatic, Baltic, and Black Seas. Sydney (Australia) was also included in the study. Thirteen countries took part in the initiative. The present study considered several fungal parameters (all fungi, several species of the genus Aspergillus and Candida and the genera themselves, plus other yeasts, allergenic fungi, dematiaceous fungi and dermatophytes). The study considered four variables that the team expected would influence the results of the analytical parameters, such as coast or inland location, urban and non-urban sites, period of the year, geographical proximity and type of sediment. The genera most frequently found were Aspergillus spp., Candida spp., Fusarium spp. and Cryptococcus spp. both in sand and in water. A site-blind median was found to be 89 Colony-Forming Units (CFU) of fungi per gram of sand in coastal and inland freshwaters, with variability between 0 and 6400 CFU/g. For freshwater sites, that number was 201.7 CFU/g (0, 6400 CFU/g (p = 0.01)) and for coastal sites was 76.7 CFU/g (0, 3497.5 CFU/g). For coastal waters and all waters, the median was 0 CFU/ml (0, 1592 CFU/ml) and for freshwaters 6.7 (0, 310.0) CFU/ml (p < 0.001). The results advocate that beaches should be monitored for fungi for safer use and better management.

Safety Evaluation of Yeasts With Probiotic Potential

This work has evaluated the safety aspects of 20 yeast strains, isolated from food environments, selected in previous works due to their probiotic potential. Among the different strains, there are Saccharomyces and non-Saccharomyces yeasts. Before safety evaluation, differentiation of Saccharomyces cerevisiae strains was done by PCR amplification of inter-δ region with pairs of primers δ2-12 and δ12-21, which showed that they were all different from each other and also had different profiles to Saccharomyces boulardii (the only commercial probiotic yeast). The non-Saccharomyces ones were already known. The evaluation tests carried out were antibiotic and antifungal resistance, production of biogenic amines, deconjugation activity of bile salts, and different enzymatic activities: coagulase, deoxyribonuclease, hemolysin, proteolytic, and phospholipase. None of the studied strains demonstrated coagulase, hemolytic or DNase capacity (clear virulence factors), although all of them showed protease activity, some showed phospholipase activity, and half of the yeasts were capable of conjugating bile salts. Regarding antimicrobial compounds, all were resistant to antibiotics but showed sensitivity to the antimycotics used. Nevertheless, only one strain of Hanseniaspora osmophila was excluded for use in the food industry, due to its high production of tyramine.

The impact of the Fungus-Host-Microbiota interplay upon Candida albicans infections: current knowledge and new perspectives

Candida albicans is a major fungal pathogen of humans. It exists as a commensal in the oral cavity, gut or genital tract of most individuals, constrained by the local microbiota, epithelial barriers and immune defences. Their perturbation can lead to fungal outgrowth and the development of mucosal infections such as oropharyngeal or vulvovaginal candidiasis, and patients with compromised immunity are susceptible to life-threatening systemic infections. The importance of the interplay between fungus, host and microbiota in driving the transition from C. albicans commensalism to pathogenicity is widely appreciated. However, the complexity of these interactions, and the significant impact of fungal, host and microbiota variability upon disease severity and outcome, are less well understood. Therefore, we summarise the features of the fungus that promote infection, and how genetic variation between clinical isolates influences pathogenicity. We discuss antifungal immunity, how this differs between mucosae, and how individual variation influences a person's susceptibility to infection. Also, we describe factors that influence the composition of gut, oral and vaginal microbiotas, and how these affect fungal colonisation and antifungal immunity. We argue that a detailed understanding of these variables, which underlie fungal-host-microbiota interactions, will present opportunities for directed antifungal therapies that benefit vulnerable patients.

Anticipatory Stress Responses and Immune Evasion in Fungal Pathogens

In certain niches, microbes encounter environmental challenges that are temporally linked. In such cases, microbial fitness is enhanced by the evolution of anticipatory responses where the initial challenge simultaneously activates pre-emptive protection against the second impending challenge. The accumulation of anticipatory responses in domesticated yeasts, which have been termed 'adaptive prediction', has led to the emergence of 'core stress responses' that provide stress cross-protection. Protective anticipatory responses also seem to be common in fungal pathogens of humans. These responses reflect the selective pressures that these fungi have faced relatively recently in their evolutionary history. Consequently, some pathogens have evolved 'core environmental responses' which exploit host signals to trigger immune evasion strategies that protect them against imminent immune attack.

Physiological characterization and molecular identification of some rare yeast species causing onychomycosis

INTRODUCTION

Onychomycosis are infections with a variety of etiological agents. Although dermatophytes are responsible for most infections, yeasts are gaining importance as agents of these pathologies. The use of antifungals has increased the incidence of what had been considered rare or novel pathogens. We reidentify three rare yeasts from a culture collection of onychomycosis agents by matrix-assisted laser desorption/ionization time of flight/mass spectrometry (MALDI-TOF/MS) and sequencing the internal transcribed spacer (ITS) regions or the intergenic spacer (IGS) 1 region of ribosomal DNA (rDNA), and present their enzymatic and antifungal susceptibility profiles.

MATERIAL AND METHODS

We performed a phenotypical characterization and molecular identification of five yeast isolates. We tested the urease, gelatinase, DNase, phospholipase, protease, and esterase activities, as well as the hemolytic activity. We evaluated the antifungal susceptibility to amphotericin B, fluconazole, anidulafungin and caspofungin.

RESULTS

Phenotypic methods could not identify the isolates. MALDI-TOF/MS was able to properly identify Candida duobushameulonii. The five isolates were successfully identified by sequence analysis as Candida duobushaemulonii, Meyerozyma caribbica and Cutaneotrichosporon dermatis. Candida duobushameulonii showed hemolytic, phospholipase, and protease activities. Meyerozyma caribbica was positive for gelatinase and protease activities. All antifungals exhibited minimum inhibitory concentrations (MICs) ≤2μg/mL against both species. The three isolates of Cutaneotrichosporon dermatis showed urease, DNase, and esterase activities, and resistance to echinocandins (MICs ≥8μg/mL), while amphotericin B and fluconazole exhibited low MICs against these isolates (0.50-2μg/mL).

DISCUSSION

Sequencing of the ITS or IGS1 regions of rDNA remains the best method for identifying cryptic species over other commercially available systems. More reports are needed to define the enzymatic and antifungal profiles for these species. This is the first report of Meyerozyma caribbica and Cutaneotrichosporon dermatis as etiological agents of onychomycosis.

Preliminary Studies on Fungal Contamination of Two Rupestrian Churches from Matera (Southern Italy)

The Sassi, a UNESCO World Heritage Site and its rupestrian churches, are richly decorated and visited by thousands of visitors every year. It is important to preserve this heritage which shows signs of deterioration due to abiotic and/or biotic factors. Aiming to carry out in the future an environmental-friendly restoration, a screening of the fungi present on walls and frescoes of two rupestrian churches “Santa Lucia alle Malve” and “La Madonna dei derelitti” located, respectively, in the “Sasso Caveoso” and in the “Sasso Barisano” was performed. Isolation and characterization of fungal species from investigated sites was carried out. Total genomic DNA (gDNA) was extracted from pure fungal cultures and subsequently utilized in PCRs using primers that amplify a portion of the ribosomal DNA (ITS5/ITS4) or the β-tubulin gene (Bt2a/Bt2b). The amplicons were directly sequenced. Obtained nucleotide sequences were compared to those present in the GenBank (NCBI) showing a very high similarity (99–100%) with the following species: Parengyodontium album, Alternaria alternata, Cladosporium cladosporioides, Lecanicillium psalliotae, Meyerozyma guilliermondii and Botryotrichum atrogriseum. All sequences from this study were deposited in the EMBL database. Detailed knowledge about fungi isolated from stone is indispensable not only to counter/reduce the structural and aesthetic damage but also to protect the health of both guardians and visitors who may develop different pathologies due to the spores diffused in the environment.

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.

Virulence properties and sensitivity profile of Candida parapsilosis complex species and Kodamaea ohmeri isolates from onychomycosis of HIV/AIDS patients

Cutaneous fungal infections include onychomycosis, an infection of the nail that affects both healthy and immunocompromised patients. This study investigated the in vitro hydrolytic enzymes production, adhesion and biofilm formation capacity of Candida parapsilosis complex species and Kodamaea ohmeri isolates from onychomycoses of HIV/AIDS patients and also established the antifungal sensitivity profiles of these isolates. Onychomycosis in HIV/AIDS patients showed a high prevalence of emerging yeasts, among which C. parapsilosis complex species and K. ohmeri were the most frequent. Three C. parapsilosis sensu stricto and two C. orthopsilosis isolates were resistant to amphotericin B and 83% of isolates were resistant to terbinafine. All three different species evaluated were proteinase and hemolysin producers. All isolates adhered to stainless steel and siliconized latex surfaces, and carbohydrates intensified adhesion of all isolates. Isolates adhered to keratinous nail and 50% formed biofilms with strong intensity. In multispecies or polymicrobial biofilms, C. albicans and Staphylococcus aureus regulated the biofilm formation of the analyzed species, decreasing the number of their cells in biofilms. The isolation of emerging yeast species from onychomycosis which are great producers of hydrolytic enzymes and with high adhesion and biofilm formation capacity is a result that should be considered relevant in clinical practice. In addition, half of the isolates was resistant to at least one of the tested antifungals. Taken together these data corroborate the infectious capacity and viability of these isolates under favorable conditions.