Current Medical Mycology最新文献

Background and purpose: Various species of microorganisms interact in a variety of ecological niches and can lead to infection. A biofilm of one or more species may form during the infectious process. Otomycosis can be brought on by etiologic agents, such as Staphylococcus aureus and Aspergillus niger. This study aimed to survey the antagonistic relationship between the gene expression biofilms of A. niger and S. aureus in the context of otomycosis-related biofilm formation.

Materials and methods: This study examined single-species biofilms of A. niger and S. aureus, as well as mixed-species biofilms of A. niger-S. aureus, over 24 and 48 h. Expression of A. niger biofilm-related genes (eng1, xynB, exo, eglA, eglB, and eglC) was analyzed using real-time polymerase chain reaction (PCR). Impact of S. aureus on the gene expression of A. niger was evaluated and compared to the gene expression of A. niger alone, which served as the control.

Results: Biofilm formation assays showed that A. niger biofilm formation was significantly inhibited when co-cultured with S. aureus, with optical density values dropping from 0.56 (alone) to 0.15 at 24 h and 0.05 at 48 h. Real-time PCR analysis revealed that the expression of A. niger biofilm-related genes, namely eng1, xynB, exo, eglA, eglB, and eglC, increased significantly in single-species biofilms, reaching 2.5, 3, 1.5, 3.5, 2, and 1.7, respectively, at 24 h and 3.5, 4, 2, 4.2, 3, and 2, respectively at 48 h. However, in co-culture with S. aureus, their gene expression was markedly reduced to 0.8, 0.5, 0.4, 0.9, 0.6, 0.5, respectively, at 24 h and 0.5, 1, 0.2, 0.8, 0.6. , and 0.3, respectively, at 48 h, demonstrating a strong inhibitory effect of S. aureus on A. niger biofilm formation and gene expression.

Conclusion: This study described the antagonistic relationship between S. aureus and A. niger on the gene expression biofilm that causes otomycosis, as well as the antibiosis relationship between the two during in vitro biofilm formation. These findings provide new insights into the complex interactions between these microorganisms during infection and may have implications for understanding and managing otomycosis.

Background and purpose: Fungal infections caused by rare pathogens are becoming an increasingly pressing problem in modern healthcare due to the severe course of the disease, high incidence of disability and mortality of patients. To study clinical and laboratory features and treatment of severe fungal infections caused by rare yeast-like pathogens in adult patients.

Materials and methods: The prospective observational non-interventional study (2004-2022) included 310 adult patients with severe fungal infections in the Kashkin Research Institute of Medical Mycology based on North-Western State Medical University named after I.I. Mechnikov, Saint-Petrsburg, Russian Federation (from October 2004 to December 2022). To identify the pathogen, we used direct microscopy, microscopy with calcofluor white, culture isolation from blood and tissue biopsies, cerebrospinal fluid or BAL fluid. Micromycete cultures were identified to species based on morphological characteristics and PCR-test.

Results: We treated 310 adult patients with severe fungal infections -10% of them caused by rare yeast-like pathogens (n=30). Analysis of the data presented a general portrait of the patient: a 30-year-old man who has been in the ICU for more than 14 days (93%). Most often, the pathogen was isolated from the blood or biofilm of the central venous catheter (77%). Isolated damage to organs and tissues (without fungemia) was diagnosed in 23% of patients (involving the central nervous system, lungs and skin). Trichosporon spр. and Rhodotorula spр. were the main pathogens (together - 73%). Despite treatment, mortality remains very high - 37%.

Conclusion: It is necessary to examine the biological substrate from the lesion daily for fungi if there is no effect from standard therapy. It is necessary to perform species identification of the pathogen and determine sensitivity to antimycotics.

Background and purpose: Cryptococcus neoformans is a pathogenic fungus that causes fungal meningitis and other infections in immunocompromised patients. The casein kinase 2 (Ck2) complex regulates cellular processes. This study provides transcriptomics and functional insights into the Ck2 complex and other pathogenic proteins of Cryptococcus neoformans as therapeutic targets.

Materials and methods: The study used computational methods to explore the transcriptomic and functional aspects of the Ck2 complex and other pathogenic proteins in Cryptococcus neoformans. RNA-sequencing analysis of control and experimental cell cultures under three different conditions (cka1Δ mutant vs wild, ckaΔ, ckb1Δ, ckb2Δ [triple] mutants vs wild, and wild vs all mutants) was performed, followed by the STRING analysis of the dysregulated genes to identify the protein-protein interactions, while Cytoscape was used to identify the hub genes in all three conditions.

Results: The RNA-sequencing analysis resulted in various dysregulated genes such as 936 (cka1Δ mutant vs wild), 1154 (triple vs wild), and 1159 (wild vs all mutants). Cellular components, molecular functions, and KEGG pathways in three conditions. The hub genes that elevated the most, Q5KFT2_CRYNJ, ARO1_CRYNJ, Q5KL19_CRYNJ, Q5KC42_CRYNJ, Q5KNI6_CRYNJ, Q5KCS1_CRYNJ, Q5KNH2_CRYNJ, Q5KA46_CRYNJ, Q5KEV1_CRYNJ, Q5KFT0_CRYNJ, Q5KAB9_CRYNJ, Q5KN73_CRYNJ, Q5KLJ6_CRYNJ, and Q5KHQ2_CRYNJ, were selected for FDA-approved drugs screening using GNINA, resulting in three potential drugs (amphotericin B, idarubicin, and candicidin) for respective proteins.

Conclusions: The Ck2 complex in C. neoformans regulates cellular processes, including proliferation and apoptosis. Disruption of this complex affects cellular functions. This study identifies deletion mutations and pathogenic proteins, revealing top-performing drugs. Further clinical investigations are needed to confirm these findings.

Background and purpose: By harnessing the power of nature, researchers can potentially discover new therapeutic options that are safe, effective, and sustainable for the management of diseases. Recently, natural products have been extensively studied for the treatment of diseases due to their diverse chemical composition and potential therapeutic properties. Therefore, this study aimed to investigate the antifungal activity of carvone and linalool against Malassezia species to find alternative treatments for pityriasis versicolor.

Materials and methods: The in vitro antifungal activity of monoterpenes was assessed using a microdilution method, following the guidelines specified in the Clinical and Laboratory Standards Institute document M27-A3 with modifications, including the use of Christensen's urea broth supplemented with various lipids to optimize the growth condition for Malassezia.

Results: The minimum inhibitory concentration ranges for linalool and carvone were found to be 0.3-5.4 and 0.3-24 mg/mL, respectively. Additionally, the growth of Malassezia species was inhibited at concentrations of 0.001-0.003 and 0.006-0.1 mg/mL for amphotericin B and ketoconazole, respectively.

Conclusion: Given the remarkable antifungal properties exhibited by linalool and carvone against Malassezia species, these terpene compounds have the potential to be utilized for the treatment of Malassezia infections, provided that additional research is conducted.

Background and purpose: This study aimed to examine the effects of essential trace elements, namely iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu), combined with D-dextrose on conidial germination and growth of Aspergillus fumigatus and Aspergillus flavus ATCC strains. Trace elements are vital in metabolic processes, acting as cofactors for various enzymes; however, their precise role in fungal pathogenesis remains poorly understood.

Materials and methods: The research involved determining the minimum inhibitory concentrations (MIC) of Fe, Mn, Zn, and Cu for Aspergillus ATCC strains. Following MIC assessment, optimized concentrations of the trace elements (~140 and 550 pM) and various concentrations of D-dextrose (1-3% w/v) were introduced to assess their effects on fungal growth in RPMI 1640 broth. Growth was measured in terms of optical density, while conidial germination rates were also observed.

Results: The MICs for Fe, Mn, and Zn were found to exceed 35 µM, while Cu exhibited lower MICs of 2 and 7.6 µM against A. fumigatus and A. flavus, respectively. At optimized concentrations, Fe, Mn, Zn, and Cu significantly enhanced fungal growth in both Aspergillus species. Additionally, growth rates increased proportionally with higher D-dextrose concentrations. Notably, the combination of enriched trace elements and D-dextrose resulted in up to 98% conidial germination.

Conclusion: The findings demonstrate that optimized concentrations of essential trace elements and D-dextrose significantly promote conidial germination and growth of Aspergillus species in vitro. These results suggest that trace element supplementation might have important implications for immunocompromised and hyperglycemic patients. Further studies are warranted to explore the interactions between these micronutrients in fungal physiology and pathogenesis.

Background and purpose: Yeasts of the Candida genus are responsible for localized and disseminated infections, especially in immunocompromised populations. These infections are exacerbated by the rapid increase in drug-resistant strains, which limits treatment options and increases patient morbidity and mortality. Therefore, the utilization of easily accessible natural products as alternatives to conventional medicines has gained interest. South Africa is home to a rich biodiverse natural flora of which many are known for their antimicrobial activity, including the antifungal effects of their plant extracts. Galenia africana (kraalbos) is a local indigenous plant found to have various traditional uses, including the treatment and prevention of various human infections.

Materials and methods: In this study, the activity of G. africana against Candida albicans and Candida glabrata preformed biofilm formation and its antibiofilm activity were tested using the xCELLigence system, which monitors biofilm formation in real time using impedance.

Results: Presence of G. africana resulted in a dose-dependent decrease in Candida biofilms and was found to be effective in the prevention of Candida biofilm formation and disruption of the existing Candida biofilms.

Conclusion: The xCELLigence impedance-based system proved to be an effective tool for medication screening. To the best of our knowledge, this is the first reported study to use real-time monitoring of a medicinal plant on microbial biofilm formation.

Background and purpose: This study analyzed the species diversity and antifungal drug sensitivity of Candida isolates reported from 2019 to 2023 at our hospital to guide empirical treatment protocols.

Materials and methods: Clinical samples were cultured by standard microbiological techniques; subsequently, yeast isolates deemed clinically significant were identified and tested for antifungal drug sensitivity using the Vitek 2 Compact system (BioMerieux, France). Statistical analysis was performed in SPSS software and P-values of less than 0.05 were considered statistically significant.

Results: Diversity of species as well as the antifungal drug resistance of Candida isolates increased markedly over the period of 5 years. Moreover, a high percentage of isolates resistant to Amphotericin B and Voriconazole was noted.

Conclusion: These findings emphasized the need for caution in the empirical use of antifungal medications. Similar surveillance at regional levels is necessary and antifungal drug sensitivity should be included in hospital antibiograms to prevent the spread of multi-drug-resistant nosocomial strains.

Background and purpose: Dermatophytosis, a fungal infection targeting keratinized tissue, is caused by dermatophytes, commonly affecting skin, hair, and nails. Prevalent in tropical regions, such as India, its treatment typically utilizes systemic and topical antifungal medications. Despite ample research on oral antifungals, data on the susceptibility of topical treatments, especially in India, where they are prevalent, remains scarce. This study aimed to investigate the antifungal susceptibility of efinaconazole, tavaborole, luliconazole, and sertaconazole against dermatophytes isolated from cases of dermatophytosis.

Materials and methods: Samples of all the clinically diagnosed cases of dermatophytosis were subjected to microscopy and culture. All 204 dermatophytes, namely Trichophyton rubrum (n=90), Trichophyton mentagrophytes/interdigitale (n=69), Trichophyton tonsurans (n=44), and Epidermophyton floccosum (n=1) were subjected to antifungal susceptibility testing for efinaconazole, tavaborole, sertaconazole, and luliconazole per Clinical Laboratory Standards Institute broth microdilution method (M38-A3).

Results: The minimum inhibitory concentration values for efinaconazole, tavaborole, sertaconazole, and luliconazole were within the ranges of 0.008-0.5, 1-2, 0.128-2, and 0.004-0.008 µg/ml, respectively across all dermatophytes. Epidemiological cutoff values (ECVs) were 0.004 µg/ml for luliconazole and 2 µg/ml for tavaborole for all dermatophytes. Sertaconazole ECVs were 2 µg/ml for T. rubrum and T. mentagrophytes/interdigitale, 0.5 µg/ml for T. tonsurans, and 1 µg/ml for E. floccosum. Tavaborole ECVs for T. mentagrophytes/interdigitale, T. tonsurans, T. rubrum, and E. floccosum were 0.5, 0.5, 0.25, and 0.016 µg/ml, respectively.

Conclusion: The results from the present study on the in vitro performance of newer topical antifungals suggested that they hold significant promise as prospective candidates for advancing the development of new antifungal treatments for dermatophytosis.

Background and purpose: Due to the ability of Candida auris, a multidrug-resistant human fungal pathogen, to colonize the skin and hospital surfaces, it is pertinent to control its nosocomial outbreaks through rapid diagnosis. Delayed and improper diagnosis of C. auris due to misidentification becomes a major hurdle in the prevention of employment of efficient therapeutics leading to the development of drug resistance. The culture-based methods are slow and less sensitive while PCR-based methods are costly. Loop-mediated amplification (LAMP) is a feasible alternative, but it fails to differentiate between live and dead cells. Therefore, this study aimed to evaluate the diagnostic efficiency of the reverse transcription (RT) LAMP approach and compare it with that of the LAMP assay for the detection of C. auris.

Materials and methods: RT-LAMP method was developed for the detection of C. auris and its clinical isolates. The limit of detection (LOD), sensitivity, and specificity were evaluated for the developed method using culture RNA. The RT-LAMP reaction for C. auris detection was standardized using the primers of a specific 869-bp DNA segment (accession no. XM_018317007), encoding a pyruvate: ferredoxin oxidoreductase domain, from the genome of C. auris.

Results: The LOD for the RT-LAMP method was 1ag contrary to 10fg for LAMP method using DNA. Specificity was 100% as determined using a gram-negative bacteria and several other Candida species. The RT-LAMP method was intraspecific and displayed no cross reaction even with closely related Candida species. The RT-LAMP method was validated on 10 clinical isolates of C. auris and showed 100% concordance with a culture-based method.

Conclusion: The RT-LAMP-based method in the present study offered a proof of concept that warrants clinical validation on a large number of samples. Therefore, its diagnostic potential for the rapid, sensitive, and specific detection of C. auris could be further exploited in resource-limited regions.

Background and purpose: Invasive candidiasis (IC) in the hospitalized population is one of the leading causes of invasive fungal infections (IFIs). Microbiological diagnosis of IC suffers due to poor sensitivity of blood culture and relative inaccessibility to more sensitive modalities. (1, 3)-β-D-glucan (BDG) is a cell wall polysaccharide found in a range of fungi. Various commercial assays are available based on various detection techniques. This study aimed to assess the diagnostic performance of the FungiXpert® Fungus BDG Detection Kit by Genobio Pharmaceutical Co. Ltd. (Tianjin, China), based on chemiluminescent method, for diagnosis of candidemia and deep-seated candidiasis.

Materials and methods: In total, 80 patients (34 males and 46 females) were included with a median age of 35 years old. In accordance with EORTC/MSGERC definitions, 39 patients had proven IC. The number of patients within the probable, possible, and no IC (taken as control) groups were 8, 4, and 29, respectively. Blood samples were collected for fungal blood culture and BDG assay.

Results: After exclusion of cases with evidence of concurrent IFI other than IC, median serum BDG was 0.63 ng/ml for proven IC; while it was 0.04 ng/ml for NO IC. Sensitivity, specificity, positive, and negative predictive values were 60.52%, 81.81%, 85.18%, and 54.54%, respectively. Positive likelihood ratio was 3.32. While the assay performed best for Candida tropicalis with median BDG of 1.92 ng/ml and sensitivity of 92.3%, its performance was worst for Candida parapsilosis, with median BDG of 0.04 ng/ml and sensitivity of 44.44%. Overall mortality rate was 65.62% in the BDG positive group, which was significantly higher than that in the BDG negative group (33.33%).

Conclusion: The performance of the FungiXpert® Fungus BDG Detection Kit was acceptable for invasive candidiasis in the present resource-limited setup. The major advantages of this assay were the ease of performance in a semi-automated cartridge format, relatively lower cost per test, non-reliance on glucan-free procedures or instruments and minimal hands-on procedure.