Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans, Staphylococcus aureus, and Candida spp.

BACKGROUND: The oral cavity harbors more than 700 species of bacteria, which play crucial roles in the development of various oral diseases including caries, endodontic infection, periodontal infection, and diverse oral diseases. AIM: To investigate the antimicrobial action of Cymbopogon Schoenanthus and Pelargonium graveolens essential oils against Streptococcus mutans, Staphylococcus aureus, Candida albicans, Ca. dubliniensis, and Ca. krusei. METHODS: Minimum microbicidal concentration was determined following Clinical and Laboratory Standards Institute documents. The synergistic antimicrobial activity was evaluated using the Broth microdilution checkerboard method, and the antibiofilm activity was evaluated with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay. Data were analyzed by one-way analysis of variance followed by the Tukey post-hoc test (P ≤ 0.05). RESULTS: C. schoenanthus and P. graveolens essential oils were as effective as 0.12% chlorhexidine against S. mutans and St. aureus monotypic biofilms after 24 h. After 24 h P. graveolens essential oil at 0.25% was more effective than the nystatin group, and C. schoenanthus essential oil at 0.25% was as effective as the nystatin group. CONCLUSION: C. schoenanthus and P. graveolens essential oils are effective against S. mutans, St. aureus, Ca. albicans, Ca. dubliniensis, and Ca. krusei at different concentrations after 5 min and 24 h.

Proposing an Affordable Plasma Device for Polymer Surface Modification and Microbial Inactivation.

This study proposes an affordable plasma device that utilizes a parallel-plate dielectric barrier discharge geometry with a metallic mesh electrode, featuring a straightforward 3D-printed design. Powered by a high-voltage supply adapted from a cosmetic plasma device, it operates on atmospheric air, eliminating the need for gas flux. Surface modification of polyethylene treated with this device was characterized and showed that the elemental composition after 15 min of plasma treatment decreased the amount of C to ~80 at% due to the insertion of O (~15 at%). Tested against Candida albicans and Staphylococcus aureus, the device achieved a reduction of over 99% in microbial load with exposure times ranging from 1 to 10 min. Simultaneously, the Vero cell viability remained consistently high, namely between 91% and 96% across exposure times. These results highlight this device's potential for the surface modification of materials and various infection-related applications, boasting affordability and facilitating effective antimicrobial interventions.

Experimental study of specific and nonspecific blood culture bottles for the diagnosis of candidemia.

BACKGROUND: Early diagnosis of candidemia is critical for the correct management and treatment of patients. AIMS: To test the efficacy of different blood culture bottles in the growth of Candida strains. METHODS: We compared the performance of BD BACTEC™ Plus Aerobic/F (Aero) culture bottles with the specific BD BACTEC™ Mycosis IC/F Lytic (Myco) culture bottles using the BD BACTEC™ FX 40 automated blood culture system to determine the mean time-to-detection (TTD) in Candida species. One isolate each of six Candida species was inoculated into blood culture bottles (final concentration, 1-5CFUml-1) and incubated at 37°C until automated growth detection. RESULTS: Candida albicans and Nakaseomyces glabratus (Candida glabrata) were detected earlier in the specific culture bottle, whereas Candida tropicalis was detected earlier in the nonspecific bottle; Candida parapsilosis, Pichia kudriavzevii (Candida krusei), and Meyerozyma guilliermondii (Candida guilliermondii) presented similar TTD in both bottles. CONCLUSIONS: Our study suggests the suitability of using both bottles in clinical laboratories for a faster diagnosis and prompt starting of any treatment.

Virulence-Related Genes Expression in Planktonic Mixed Cultures of Candida albicans and Non-Albicans Candida Species.

INTRODUCTION: Candida albicans is the most common opportunistic pathogen causing fungal infections worldwide, especially in high-risk patients. Its pathogenicity is related to virulence factors gene expression, such as hyphal growth (HWP1), cell adhesion (ALS3), and protease secretion (SAP1) during infection spreading mechanisms. In recent years, an increase in non-albicans Candida infections has been reported, which may present coinfection or competitive interactions with C. albicans, potentially aggravating the patient's condition. This study aims to evaluate the expression of genes related to virulence factors of C. albicans and non-albicans Candida during planktonic stage. METHODS: C. albicans (ATCC MYA-3573) as well as with three clinical strains (C. albicans DCA53, C. tropicalis DCT6, and C. parapsilosis DCP1) isolated from blood samples, were grown in 24-well plates at 37°C for 20 h, either in monocultures or mixed cultures. Quantitative real-time polymerase chain reaction was used to evaluate the expression levels of the genes HWP1, ALS3, and SAP1 in cells collected during the planktonic stage. In addition, hyphal filamentation was observed using a Scanning Electron Microscope. RESULTS: The overexpression of HWP1 and ASL3 genes in mixed growth conditions between C. albicans and non-albicans Candida species suggests a synergistic relationship as well as an increased capacity for hyphal growth and adhesion. In contrast, C. parapsilosis versus C. tropicalis interaction shows an antagonistic relationship during mixed culture, suggesting a decreased virulence profile of C. parapsilosis during initial coinfection with C. tropicalis. CONCLUSION: The expression of HWP1, ALS3, and SAP1 genes associated with virulence factors varies under competitive conditions among species of the genus Candida during planktonic stage.

Salivary proteins modulate Candida albicans virulence and may prevent oropharingeal candidiasis.

Oral candidiasis can be presented in different ways due to the virulence factors of its etiology such as Candida albicans that have developed an effective set of these factors that are able to improve its pathogenesis. The role of salivary immunological components in the development of candidiasis can provide insights for the development of new methodologies aiming to control this disease. The aim of this study was to evaluate the antifungal activity of two salivary components, histatin 5 and lactoferrin on C. albicans viability and virulence using a fluconazole resistant C. albicans clinical strain. Results showed that histatin 5 and lactoferrin decreased cell viability, and the cell surface hydrophobicity was increased by 18% in presence of 151 µg/mL of histatin 5 but was not altered by lactoferrin. It was observed the reduction of 69.3% in the expression of mannoproteins on C. albicans surface in the presence of 151 µg/mL of histatin, but proteolytic activity of serine proteinases was not inhibited by any of the proteins. Histatin 5 altered cell ultrastructure predominantly in the cytoplasmic compartment. However, this peptide does not interfere with mitochondrial function neither in membrane permeability of the yeasts. The association index between C. albicans and epithelial cells was increased by 51% in presence of 151 µg/mL of histatin. Results suggest that histatin 5 and lactoferrin affects viability and virulence of C. albicans at physiological levels, and the maintenance of these levels may be essential in the prevention of oropharyngeal candidiasis. Exogenous administration of these proteins may become a therapeutic alternative for resistant strains of C. albicans, circumventing toxicity issues, considering their constitutive features.

The arrangement of dual-species biofilms of Candida albicans and Issatchenkia orientalis can be modified by the medium: effect of Voriconazole.

Both Candida albicans and Issatchenkia orientalis have been isolated from different types of infections over the years. They have the ability to form communities of microorganisms known as biofilms. It has been demonstrated that the medium employed in studies may affect the biofilm development. The aim of this study was to investigate the arrangement of dual-species biofilms of C. albicans and I. orientalis cultivated on either RPMI-1640 or Sabouraud Dextrose Broth (SDB), as well as the inhibitory effect of Voriconazole (VRC). For the experiments performed, ATCC strains were used, and yeast-mixed suspensions were inoculated in 96-well plates with either RPMI-1640 or SDB, in the presence or absence of VRC. The results were observed by counting the number of CFU obtained from scraping off the biofilms produced and plating the content on CHROMagar Candida medium. It was observed that for all conditions tested the medium chosen affected the arrangement of dual-species biofilms: when RPMI-1640 was used, there was a prevalence of C. albicans, while the opposite was noted when SDB was used. It could be suggested that the medium and environment could regulate interactions between both yeast species, including the response to different antifungal drugs.

Microbicidal Polymer Nanoparticles Containing Clotrimazole for Treatment of Vulvovaginal Candidiasis.

Vulvovaginal candidiasis (VVC) alters the innate cervicovaginal immunity, which provides an important barrier against viruses and other infections. The incidence of this disease has not decreased in the last 30 years, so effective treatments are still needed. Nanoparticles (NPs) of cellulose acetate phthalate (CAP) and clotrimazole (CLZ) were prepared by the emulsification-diffusion method. NPs were characterized using dynamic light scattering, atomic force microscopy and differential scanning calorimetry; their release profile was determined by the dialysis bag technique and mucoadhesion was evaluated with the mucin-particle method. The growth inhibition study of Candida albicans was carried out using the plate counting technique. Finally, accelerated physical stability tests of NPs were carried out, both in water and in SVF. The CAP-CLZ NPs had an average diameter of 273.4 nm, a PDI of 0.284, smooth surfaces and spherical shapes. In vitro release of CLZ from the CAP NPs was categorized with the Weibull model as a matrix system in which initial release was rapid and subsequently sustained. The inhibition of C. albicans growth by the CAP-CLZ NPs was greater than that of free CLZ, and the CAP-only NPs had a microbicidal effect on C. albicans. The NPs showed poor mucoadhesiveness, which could lead to studies of their mucopenetration capacities. An accelerated physical stability test revealed the erosion of CAP in aqueous media. A nanoparticulate system was developed and provided sustained release of CLZ, and it combined an antifungal agent with a microbial polymer that exhibited antifungal activity against C. albicans.

Can Gentisic Acid Serve as a High-Performance Antioxidant with Lower Toxicity for a Promising New Topical Application?

Gentisic acid (2,5-dihydroxybenzoic acid) is primarily found naturally in plants and has demonstrated a significant range of biological activities; however, its efficacy and safety as a topical application ingredient are not yet well established. Thus, the compound's potential antioxidant and antimicrobial properties were evaluated for efficacy, while the cytotoxicity was evaluated for safety. The antioxidant activity, measured by the DPPH kinetic method, showed an Efficiency Concentration (EC50) of 0.09 with an antioxidant reducing power (ARP) of 11.1. The minimum inhibitory concentration (MIC) against Staphylococcus aureus was 4.15 mg/mL, Escherichia coli was 4.00 mg/mL, Candida albicans was 3.00 mg/mL, and Cutibacterium acnes was 3.60 mg/mL, and the MIC for C. acnes has remained unpublished until now. The substance showed low cytotoxicity by the neutral red uptake (NRU) methodology against HaCat, HDFa, and HepG2 cells at concentrations of up to 10.0, 7.3, and 4.0 mM, respectively, also representing unpublished data. This evidence demonstrates gentisic acid as a promising active substance for skin topical application in the cosmetic or pharmaceutical industry.

Inhibition of Development and Metabolism of Dual-Species Biofilms of Candida albicans and Candida krusei (Pichia kudriavzevii) by Organoselenium Compounds.

Although Candida albicans is the most frequently identified Candida species in clinical settings, a significant number of infections related to the non-albicans Candida (NAC) species, Candida krusei, has been reported. Both species are able to produce biofilms and have been an important resistance-related factor to antimicrobial resistance. In addition, the microbial relationship is common in the human body, contributing to the formation of polymicrobial biofilms. Considering the great number of reports showing the increase in cases of resistance to the available antifungal drugs, the development of new and effective antifungal agents is critical. The inhibitory effect of Organoselenium Compounds (OCs) on the development of Candida albicans and Candida krusei was recently demonstrated, supporting the potential of these compounds as efficient antifungal drugs. In addition, OCs were able to reduce the viability and the development of biofilms, a very important step in colonization and infection caused by fungi. Thus, the objective of this study was to investigate the effect of the Organoselenium Compounds (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2 on the development of dual-species biofilms of Candida albicans and Candida krusei produced using either RPMI-1640 or Sabouraud Dextrose Broth (SDB) media. The development of dual-species biofilms was evaluated by the determination of both metabolic activity, using a metabolic assay based on the reduction of XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide sodium salt) assay and identification of either Candida albicans and Candida krusei on CHROMagar Candida medium. Biofilm formation using RPMI-1640 was inhibited in 90, 55, and 20% by 30 µM (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2, respectively. However, biofilms produced using SDB presented an inhibition of 62, 30 and 15% in the presence of 30 µM (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2, respectively. The metabolic activity of 24 h biofilms was inhibited by 35, 30 and 20% by 30 µM (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2, respectively, with RPMI-1640; however, 24 h biofilms formed using SDB were not modified by the OCs. In addition, a great reduction in the number of CFUs of Candida albicans (93%) in biofilms produced using RPMI-1640 in the presence of 30 µM (p-MeOPhSe)2 was observed. However, biofilms formed using SDB and treated with 30 µM (p-MeOPhSe)2 presented a reduction of 97 and 69% in the number of CFUs of Candida albicans and Candida krusei, respectively. These results demonstrated that Organoselenium Compounds, mainly (p-MeOPhSe)2, are able to decrease the metabolic activity of dual-species biofilms by reducing both Candida albicans and Candida krusei cell number during biofilm formation using either RPMI-1640 or SDB. Taken together, these results demonstrated the potential of the OCs to inhibit the development of dual-species biofilms of Candida albicans and Candida krusei.

Antifungal Synergy: Mechanistic Insights into the R-1-R Peptide and Bidens pilosa Extract as Potent Therapeutics against Candida spp. through Proteomics.

Previous reports have demonstrated that the peptide derived from LfcinB, R-1-R, exhibits anti-Candida activity, which is enhanced when combined with an extract from the Bidens pilosa plant. However, the mechanism of action remains unexplored. In this research, a proteomic study was carried out, followed by a bioinformatic analysis and biological assays in both the SC5314 strain and a fluconazole-resistant isolate of Candida albicans after incubation with R-1-R. The proteomic data revealed that treatment with R-1-R led to the up-regulation of most differentially expressed proteins compared to the controls in both strains. These proteins are primarily involved in membrane and cell wall biosynthesis, membrane transport, oxidative stress response, the mitochondrial respiratory chain, and DNA damage response. Additionally, proteomic analysis of the C. albicans parental strain SC5314 treated with R-1-R combined with an ethanolic extract of B. pilosa was performed. The differentially expressed proteins following this combined treatment were involved in similar functional processes as those treated with the R-1-R peptide alone but were mostly down-regulated (data are available through ProteomeXchange with identifier PXD053558). Biological assays validated the proteomic results, evidencing cell surface damage, reactive oxygen species generation, and decreased mitochondrial membrane potential. These findings provide insights into the complex antifungal mechanisms of the R-1-R peptide and its combination with the B. pilosa extract, potentially informing future studies on natural product derivatives.

The sunflower jacalin Helja: biological and structural insights of its antifungal activity against Candida albicans.

The limited availability of efficient treatments for Candida infections and the increased emergence of antifungal-resistant strains stimulates the search for new antifungal agents. We have previously isolated a sunflower mannose-binding lectin (Helja) with antifungal activity against Candida albicans, capable of binding mannose-bearing oligosaccharides exposed on the cell surface. This work aimed to investigate the biological and biophysical basis of Helja's binding to C. albicans cell wall mannans and its influence on the fungicidal activity of the lectin. We evaluated the interaction of Helja with the cell wall mannans extracted from the isogenic parental strain (WT) and a glycosylation-defective C. albicans with altered cell wall phosphomannosylation (mnn4∆ null mutants) and investigated its antifungal effect. Helja exhibited stronger antifungal activity on the mutant strain, showing greater inhibition of fungal growth, loss of cell viability, morphological alteration, and formation of clusters with agglutinated cells. This differential biological activity of Helja was correlated with the biophysical parameters determined by solid phase assays and isothermal titration calorimetry, which demonstrated that the lectin established stronger interactions with the cell wall mannans of the mnn4∆ null mutant than with the WT strain. In conclusion, our results provide new evidence on the nature of the Helja molecular interactions with cell wall components, i.e. phosphomannan, and its impact on the antifungal activity. This study highlights the relevance of plant lectins in the design of effective antifungal therapies.

Interkingdom biofilm of Streptococcus pyogenes and Candida albicans: establishment of an in vitro model and dose-response validation of antimicrobials.

Although Streptococcus pyogenes and Candida albicans may colonize tonsillar tissues, the interaction between them in mixed biofilms has been poorly explored. This study established an interkingdom biofilm model of S. pyogenes and C. albicans and verified the dose-response validation of antimicrobials. Biofilms were formed on microplates, in the presence or absence of a conditioning layer of human saliva, using Brain Heart Infusion (BHI) broth or artificial saliva (AS) as a culture medium, and with variations in the microorganism inoculation sequence. Biofilms grown in AS showed higher mass than those grown in BHI broth, and an opposite trend was observed for metabolism. The number of S. pyogenes colonies was lower in AS. Amoxicillin and nystatin showed dose-dependent effects. The inoculation of the two species at the same time, without prior exposure to saliva, and using BHI broth would be the model of choice for future studies assessing the effects of antimicrobials on dual S. pyogenes/C. albicans biofilms.

The synergistic effect of photodynamic and sonodynamic inactivation against Candida albicans biofilm.

Candida albicans biofilm can cause diseases that are resistant to conventional antifungal agents. Photodynamic (PDI), sonodynamic (SDI), and sonophotodynamic (SPDI) inactivation have arisen as promising antimicrobial strategies. This study evaluated these treatments mediated by curcumin against C. albicans biofilms. For this, C. albicans biofilms were submitted to PDI, SDI, or SPDI with different light and ultrasound doses, then, the viability assay was performed to measure the effectiveness. Finally, a mathematical model was suggested to fit acquired experimental data and understand the synergistic effect of light and ultrasound in different conditions. The results showed that SPDI, PDI, and SDI reduced the viability in 6 ± 1; 1 ± 1; and 2 ± 1 log, respectively, using light at 60 J/cm2, ultrasound at 3 W/cm2, and 80 µM of curcumin. The viability reduction was proportional to the ultrasound and light doses delivered. These results encourage the use of SPDI for the control of microbial biofilm.

Antimicrobial gel with silver vanadate and silver nanoparticles: antifungal and physicochemical evaluation.

Aim: To develop a ß-AgVO3 gel and evaluate its physicochemical stability and antifungal activity against Candida albicans. Materials & methods: The gel was prepared from the minimum inhibitory concentration (MIC) of ß-AgVO3. The physicochemical stability was evaluated by centrifugation, accelerated stability (AS), storage (St), pH, syringability, viscosity and spreadability tests and antifungal activity by the agar diffusion. Results: The MIC was 62.5 µg/ml. After centrifugation, AS and St gels showed physicochemical stability. Lower viscosity and higher spreadability were observed for the higher ß-AgVO3 concentration and the minimum force for extrusion was similar for all groups. Antifungal effect was observed only for the ß-AgVO3 gel with 20xMIC. Conclusion: The ß-AgVO3 gel showed physicochemical stability and antifungal activity.

We used silver and vanadium to make a gel that can kill fungi in the mouth. We looked at the color of the gel, it's smell and also checked how well it lasted. The gel turned yellow and had no smell and did not spoil for at least 2 months. When we tested the gel against a type of fungus, it worked as well as another medicine called chlorhexidine, which is sold in pharmacies. But when we compared it with another medicine called nystatin, our gel was not as effective in killing the fungus.

Antifungal Activity of Morinda citrifolia Methanolic Extract against Candida albicans: An In Vitro Study.

Aim: Natural medicine used as an alternative and/or complementary treatment to counteract diseases is of great importance in public health. Therefore, the purpose of the present study was to assess the in vitro antifungal activity of Morinda citrifolia methanolic extract of peel, pulp, and seed against Candida albicans. Materials and Methods: The present study was experimental in vitro and cross-sectional. Eight replicates were prepared in Sabouraud dextrose agar with five wells each, where 0.12% chlorhexidine, distilled water, and methanolic extract of seed, peel, and pulp of Morinda citrifolia fruit were placed at concentrations of 10,690, 8,270, and 6,430 mg/mL, respectively, to evaluate sensitivity according to Duraffourd's scale. In addition, the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined by dilution and agar seeding method. Statistical analysis was performed by analysis of variance (ANOVA) and Tukey's post hoc test, considering a significance level of P < 0.05. Results: The inhibition halos of Morinda citrifolia methanolic extract of seed, peel, and pulp against Candida albicans measured on average 15.94, 11.94, and 11.56 mm, respectively. The MIC of seed, peel, and pulp extract were 1366.25, 2067.5, and 1607.5 mg/mL respectively, whereas the MFC for seed, peel, and pulp extract were 2672.50, 2067.5, and 3215 mg/mL, respectively. Moreover, seed extract presented significantly higher antifungal activity than peel and pulp (P < 0.001). Conclusions: Morinda citrifolia methanolic extract of peel, pulp, and seed showed fungistatic and fungicidal effect against Candida albicans, being this very sensitive to seed extract with a MIC of 1366.25 mg/mL and a MFC of 2672.5 mg/mL, which allows recommending the development of effective pharmacological formulations for the control of candidiasis.

Saps1-3 Antigens in Candida albicans: Differential Modulation Following Exposure to Soluble Proteins, Mammalian Cells, and Infection in Mice.

The secreted aspartic peptidases (Saps) of Candida albicans play crucial roles in various steps of fungal-host interactions. Using a flow cytometry approach, this study investigated the expression of Saps1-3 antigens after (i) incubation with soluble proteins, (ii) interaction with mammalian cells, and (iii) infection in immunosuppressed BALB/c mice. Supplementation strategies involving increasing concentrations of bovine serum albumin (BSA) added to yeast carbon base (YCB) medium as the sole nitrogenous source revealed a positive and significant correlation between BSA concentration and both the growth rate and the percentage of fluorescent cells (%FC) labeled with anti-Saps1-3 antibodies. Supplementing the YCB medium with various soluble proteins significantly modulated the expression of Saps1-3 antigens in C. albicans. Specifically, immunoglobulin G, gelatin, and total bovine/human sera significantly reduced the %FC, while laminin, human serum albumin, fibrinogen, hemoglobin, and mucin considerably increased the %FC compared to BSA. Furthermore, co-cultivating C. albicans yeasts with either live epithelial or macrophage cells induced the expression of Saps1-3 antigens in 78% (mean fluorescence intensity [MFI] = 152.1) and 82.7% (MFI = 178.2) of the yeast cells, respectively, compared to BSA, which resulted in 29.3% fluorescent cells (MFI = 50.9). Lastly, the yeasts recovered from the kidneys of infected immunosuppressed mice demonstrated a 4.8-fold increase in the production of Saps1-3 antigens (MFI = 246.6) compared to BSA, with 95.5% of yeasts labeled with anti-Saps1-3 antibodies. Altogether, these results demonstrated the positive modulation of Saps' expression in C. albicans by various key host proteinaceous components, as well as by in vitro and in vivo host challenges.

Unmasking the Antifungal Activity of Anacardium occidentale Leaf Extract against Candida albicans.

Invasive fungal disease causes high morbidity and mortality among immunocompromised patients. Resistance to conventional antifungal drugs and the toxicity associated with high doses highlight the need for effective antifungal therapies. In this study, the antifungal potential of the ethanolic extract of Anacardium occidentale (Cashew Leaf) leaves were evaluated against Candida albicans and C. auris. The antifungal activity was tested by the broth microdilution method and growth kinetic test. To further explore its antifungal action mode, spectrofluorophotometry, confocal microscopy and scanning and transmission electron microscopy were performed. Additionally, heterozygous knockout strains associated with resistance to oxidative stress were included in the study. We found that A. occidentale could inhibit the proliferation and growth of C. albicans at concentrations of 62.5 and 125 µg/mL. The doubling time was also drastically affected, going from 2.8 h to 22.5 h, which was also observed in C. auris. The extract induced the accumulation of intracellular reactive oxygen species (ROS), resulting in endoplasmic reticulum stress and mitochondrial dysfunction, while it did not show cytotoxicity or hemolytic activity at the concentrations evaluated. Our work preliminarily elucidated the potential mechanisms of A. occidentale against C. albicans on a cellular level, and might provide a promising option for the design of a new treatment for invasive candidiasis.

Synthesis and Superficial Modification "In Situ" of Copper Selenide (Cu2-x Se) Nanoparticles and Their Antibacterial Activity.

Copper selenide nanoparticles (Cu2-x Se NPs) have received a lot of attention in recent decades due to their interesting properties and potential applications in various areas such as electronics, health, solar cells, etc. In this study, details of the synthesis and characterization of copper selenide nanoparticles modified with gum arabic (GA) are reported. Also, through transmission electronic microscopy (TEM) analysis, the transformation of the morphology and particle size of copper selenide nanoparticles in aqueous solution was studied. In addition, we present an antimicrobial study with different microorganisms such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Candida albiacans (C. albicans). Copper selenide nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry analysis (DSC) and TEM. XRD confirmed the crystal-line structure of the nanoparticles such as cubic berzelanite with a particle size of 6 nm ± 0.5. FTIR and TGA corroborated the surface modification of copper selenide nanoparticles with gum arabic, and DSC suggested a change in the structural phase from cubic to hexagonal. TEM analysis demonstrated that the surface modification of the Cu2-x Se NPs stabilized the nanostructure of the particles, preventing changes in the morphology and particle size. The antimicrobial susceptibility analysis of copper selenide nanoparticles indicated that they have the ability to inhibit the microbial growth of Staphylococcus aureus, Escherichia coli and Candida albicans.

Synergic Effect of the Antimicrobial Peptide ToAP2 and Fluconazole on Candida albicans Biofilms.

Candida albicans is one of the agents of invasive candidiasis, a life-threatening disease strongly associated with hospitalization, particularly among patients in intensive care units with central venous catheters. This study aimed to evaluate the synergistic activity of the antifungal peptide ToAP2 combined with fluconazole against C. albicans biofilms grown on various materials. We tested combinations of different concentrations of the peptide ToAP2 with fluconazole on C. albicans biofilms. These biofilms were generated on 96-well plates, intravenous catheters, and infusion tubes in RPMI medium at two maturation stages. Scanning electron microscopy and atomic force microscopy were employed to assess the biofilm structure. We also evaluated the expression of genes previously proven to be involved in C. albicans biofilm formation in planktonic and biofilm cells after treatment with the peptide ToAP2 using qPCR. ToAP2 demonstrated a synergistic effect with fluconazole at concentrations up to 25 µM during both the early and mature stages of biofilm formation in 96-well plates and on medical devices. Combinations of 50, 25, and 12.5 µM of ToAP2 with 52 µM of fluconazole significantly reduced the biofilm viability compared to individual treatments and untreated controls. These results were supported by substantial structural changes in the biofilms observed through both scanning and atomic force microscopy. The gene expression analysis of C. albicans cells treated with 25 µM of ToAP2 revealed a decrease in the expression of genes associated with membrane synthesis, along with an increase in the expression of genes involved in efflux pumps, adhesins, and filamentation. Our results highlight the efficacy of the combined ToAP2 and fluconazole treatment against C. albicans biofilms. This combination not only shows therapeutic potential but also suggests its utility in developing preventive biofilm tools for intravenous catheters.

Toll-like receptor 4 (TLR4) is the major pattern recognition receptor triggering the protective effect of a Candida albicans extracellular vesicle-based vaccine prototype in murine systemic candidiasis.

Systemic candidiasis remains a significant public health concern worldwide, with high mortality rates despite available antifungal drugs. Drug-resistant strains add to the urgency for alternative therapies. In this context, vaccination has reemerged as a prominent immune-based strategy. Extracellular vesicles (EVs), nanosized lipid bilayer particles, carry a diverse array of native fungal antigens, including proteins, nucleic acids, lipids, and glycans. Previous studies from our laboratory demonstrated that Candida albicans EVs triggered the innate immune response, activating bone marrow-derived dendritic cells (BMDCs) and potentially acting as a bridge between innate and adaptive immunity. Vaccination with C. albicans EVs induced the production of specific antibodies, modulated cytokine production, and provided protection in immunosuppressed mice infected with lethal C. albicans inoculum. To elucidate the mechanisms underlying EV-induced immune activation, our study investigated pathogen-associated molecular patterns (PAMPs) and pattern recognition receptors (PRRs) involved in EVs-phagocyte engagement. EVs from wild-type and mutant C. albicans strains with truncated mannoproteins were compared for their ability to stimulate BMDCs. Our findings revealed that EV decoration with O- and N-linked mannans and the presence of ß-1,3-glucans and chitin oligomers may modulate the activation of specific PRRs, in particular Toll-like receptor 4 (TLR4) and dectin-1. The protective effect of vaccination with wild-type EVs was found to be dependent on TLR4. These results suggest that fungal EVs can be harnessed in vaccine formulations to selectively activate PRRs in phagocytes, offering potential avenues for combating or preventing candidiasis.IMPORTANCESystemic candidiasis is a serious global health concern with high mortality rates and growing drug resistance. Vaccination offers a promising solution. A unique approach involves using tiny lipid-coated particles called extracellular vesicles (EVs), which carry various fungal components. Previous studies found that Candida albicans EVs activate the immune response and may bridge the gap between innate and adaptive immunity. To understand this better, we investigated how these EVs activate immune cells. We demonstrated that specific components on EV surfaces, such as mannans and glucans, interact with receptors on immune cells, including Toll-like receptor 4 (TLR4) and dectin-1. Moreover, vaccinating with these EVs led to strong immune responses and full protection in mice infected with Candida. This work shows how harnessing fungal EVs might lead to effective vaccines against candidiasis.