Search

The increasing prevalence of fungal strains showing acquired resistance and multidrug resistance is an increasing therapeutic problem, especially in patients with a severely weakened immune system and undergoing chemotherapy. What is also extremely disturbing is the similarity of the resistance mechanisms of fungal cells and other eukaryotic cells, including human cells, which may contribute to the development of cross-resistance in fungi in response to substances used in e.g. anticancer treatment. An example of such a drug is methotrexate, which is pumped out of eukaryotic cells by ABC transmembrane transporters - in fungi, used to remove azoles from fungal cells. For this reason, the aim of the study was to analyze the expression levels of genes: ERG11, MDR1 and CDR1, potentially responsible for the occurrence of cross-resistance in Candida albicans and Candida parapsilosis as a result of fungal exposure to methotrexate (MTX). In vitro exposure of C. albicans and C. parapsilosis strains to methotrexate showed a high increase in resistance to fluconazole and a partial increase in resistance to voriconazole. Analysis of the expression of resistance genes showed varied responses of the tested strains depending on the species. In the case of C. albicans, an increase in the expression of the MDR1 gene was observed, and a decrease in ERG11 and CDR1. However, for C. parapsilosis there was an increase in the expression of the CDR1 gene and a decrease in ERG11 and MDR1. We noted the relationship between the level of resistance to voriconazole and the level of ERG11 gene expression in C. albicans. This indicates that this type of relationship is different for each species. Our research confirms that the mechanisms by which fungi acquire resistance and develop cross-resistance are highly complex and most likely involve several pathways simultaneously. The emergence of multidrug resistance may be related to the possibility of developing tolerance to antimycotics by fungi., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Interactions between C. albicans and the microbiota play an important role in maintaining the balance between commensal and pathogenic organisms. Although the exact role of bacteria in reducing the pathogenicity of yeast remains poorly understood, a few examples have been documented so far: probiotics administration effectively reduces the formation of biofilm and bacterial metabolites inhibit the formation of hyphae. The aim of the study was to analyze C. albicans virulence levels based on the changes in the morphological structure and enzymatic profile in experimental cultures mixed with Escherichia coli. Viable cell abundance, cell pleomorphism and enzymatic profile were analyzed in single and mixed cultures (C. albicans + E. coli). The microscope analysis showed a large decrease in the number of viable C. albicans cells in mixed cultures with E. coli from 485.3±132.1 immediately after the establishment of the culture to 238.1±71.2 after an hour of incubation and 24.4±5.4 after 24 h. The length of C. albicans cells differed significantly between the single-species cultures and the mixed cultures for 24 h. Our present findings indicate a significant reduction in the secretion of several enzymes by fungi following contact with E. coli, including acid phosphatase, N-acetyl-β-glucosaminidase, naphthol-AS-BI-phosphohydrolase and leucine arylamidase. The interactions between fungi and bacteria appear to be extremely complex. On the one hand, during C. albicans with E. coli co-incubation, the bacteria stimulated the elongation of yeast cells, leading to the formation of a filamentous form; however, the number of yeast cells and their enzymatic activity decreased significantly. Therefore, it can be concluded that while E. coli stimulates some pathogenic properties, e.g. cell elongation, it also inhibits other virulence features, e.g. enzymatic activity of C. albicans., Competing Interests: Declaration of Competing Interest All authors have seen and approved the final version of the manuscript being submitted. We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. No funding was received for this work., (Copyright © 2023 SFMM. Published by Elsevier Masson SAS. All rights reserved.)

The increasing prevalence of fungal strains showing acquired resistance and multidrug resistance is an increasing therapeutic problem, especially in patients with a severely weakened immune system and undergoing chemotherapy. What is also extremely disturbing is the similarity of the resistance mechanisms of fungal cells and other eukaryotic cells, including human cells, which may contribute to the development of cross-resistance in fungi in response to substances used in e.g. anticancer treatment. An example of such a drug is methotrexate, which is pumped out of eukaryotic cells by ABC transmembrane transporters - in fungi, used to remove azoles from fungal cells. For this reason, the aim of the study was to analyze the expression levels of genes: ERG11, MDR1 and CDR1 , potentially responsible for the occurrence of cross-resistance in Candida albicans and Candida parapsilosis as a result of fungal exposure to methotrexate (MTX). In vitro exposure of C. albicans and C. parapsilosis strains to methotrexate showed a high increase in resistance to fluconazole and a partial increase in resistance to voriconazole. Analysis of the expression of resistance genes showed varied responses of the tested strains depending on the species. In the case of C. albicans , an increase in the expression of the MDR1 gene was observed, and a decrease in ERG11 and CDR1. However, for C. parapsilosis there was an increase in the expression of the CDR1 gene and a decrease in ERG11 and MDR1. We noted the relationship between the level of resistance to voriconazole and the level of ERG11 gene expression in C. albicans. This indicates that this type of relationship is different for each species. Our research confirms that the mechanisms by which fungi acquire resistance and develop cross-resistance are highly complex and most likely involve several pathways simultaneously. The emergence of multidrug resistance may be related to the possibility of developing tolerance to antimycotics by fungi. [ABSTRACT FROM AUTHOR]

In recent years, there has been a rapid increase in the incidence of Candida infections. The different species of the genus Candida vary in their virulence abilities and susceptibility to antifungal agents, depending on several external factors. The result of such modifications may be cross-resistance, which is understood as an acquired resistance to a certain antimicrobial agent after exposure to another drug. The aim of this study was to determine the possibility of cross-resistance between fluconazole, voriconazole, itraconazole, and methotrexate in Candida albicans and Meyerozyma guilliermondii (syn. Candida guilliermondii). Fieen strains of M. guilliermondii and eight strains of C. albicans, including the standard strains, were tested. For all strains, the minimum inhibitory concentrations (MICs) for fluconazole, voriconazole, and itraconazole were determined before and after stimulation with methotrexate. The median MICs in M. guilliermondii before and after stimulation were 9.333 and 64 mg/L (p =0.005) for fluconazole; 0.917 and 1.667 mg/L (p =0.001) for itraconazole, respectively. No significant change in MIC was observed for voriconazole. For C. albicans strains, the median MICs before and after stimulation were 0.917 and 64 mg/L (p =0.012) for fluconazole; 0.344 and 1.135 mg/L (p =0.018) for voriconazole, respectively. There was no significant change in MIC values for itraconazole. Thus, this study demonstrates the presence of cross-resistance between voriconazole, itraconazole, fluconazole, and methotrexate for the selected strains. Methotrexate exposure induces different responses when certain drugs are used for various species. Therefore, if a patient was previously exposed to methotrexate, there may be a higher risk of treatment failure with fluconazole than with other azoles such as voriconazole for fungemia caused by M. guilliermondii or itraconazole for C. albicans infection. [ABSTRACT FROM AUTHOR]

Fungal infections are commonly reported among outdoor bathers. Recreational water reservoirs are an important element of the mycosis epidemiological chain in the biosphere because they can be a source of fungi from municipal wastes, of asymptomatic carriers or bathers carrying mycoses. Yeast-like fungi and moulds were isolated from samples of four surface water baths and five swimming pools in 2011-2012. Membrane filters and standard laboratory-based protocols were used to identify the isolated fungi. In total, 51 saprotrophic and potentially pathogenic species classified in the biosafety level-2 group were found. In one of the eutrophic lakes, a positive correlation was observed between the frequency of trading and the presence of coliform yeasts, while in the second, a correlation was found between the number of species of fungi and the presence of faecal streptococci. In swimming pool waters, the key factors that determined higher numbers of fungi were increased temperature, followed by low concentrations of chlorine ions. Together with the bacteriological and physicochemical analysis, constant mycological monitoring of recreational water (lake pools and swimming pools) should be a standard inspection element to reduce sanitary and epidemiologic risks to people using these water reservoirs for recreational purposes. [ABSTRACT FROM AUTHOR]

Migratory water birds, including the Mallard (Anas platyrhynchos) – one of the most abundant waterfowl species – are involved in the dispersal of microfungi. This study was undertaken to collect data on the possible differences in fungal biota between mallards in urban and non-urban areas. In total, 53 species of microfungi were found in samples taken from the bill cavity and the cloaca. Among them, 19% are pathogens of humans, including the most common fungus, Candida albicans (18.0% of all isolates). Mallards living in proximity to humans were colonised with a higher number of fungal species than were birds living in non-urban areas. This might be the result of conditions that are favourable for microfungi in cities. The differences between the urban and non-urban environments are responsible for the higher levels of similarity in the species structure of the fungi found in the bill cavity and the cloaca within the same environment rather than in the same ontocenoses from different sites. [ABSTRACT FROM AUTHOR]

Introduction: An increasing number of reports have been issued in the recent years on considerably increased frequency of yeast-like fungi and yeast in organ ontocenoses of man. This applies in particular the respiratory and digestive systems. Aim of the study: The aim of this study was the taxonomical analysis of yeast and yeast-like fungi from the respiratory system and gastrointestinal tract of human with particular emphasis on the number of taxa and attention to the dominant species and rare species in the different sections of studied ontocenosis. Material and methods: The experimental material were yeast-like fungi and yeasts isolated from the respiratory and the digestive system of human. The fungi were cultured and identified following standard principles of mycological diagnostics. Results: The fungi isolated from the respiratory system were classified to 37 species and from the gastrointestinal tract – to 23 species. The predominating species turned out to be the Candida albicans, constituting 19.49% in the respiratory system and 27.87% in the digestive system. Conclusions: Five species have been isolated for the first time in Poland. The abundance of the species detected and the presence of perfect stages in the material examined imply a successive increase in the expansiveness of fungi towards human tissues. Results obtained confirms that the respiratory systems affords the fungi better conditions for the survival and growth. [ABSTRACT FROM AUTHOR]