Candida albicans pathogenicity mechanisms

Candida species covered from traditional cheeses: Characterization of C. albicans regarding virulence factors, biofilm formation, caseinase activity, antifungal resistance and phylogeny

This study has provided characterization data (carriage of virulence, antifungal resistance, caseinase activity, biofilm-forming ability and genotyping) of Candida albicans isolates and the occurrence of Candida species in traditional cheeses collected from Kayseri, Türkiye. Phenotypic (E-test, Congo red agar and microtiter plate tests) and molecular tests (identification, virulence factors, biofilm-formation, antifungal susceptibility) were carried out. The phylogenetic relatedness of C. albicans isolates was obtained by constructing the PCA dendrogram from the mass spectra data. Of 102 samples, 13 (12.7%) were found to be contaminated with C. albicans, 15 (14.7%), 10 (9.8%) and five (4.9%) were found to be contaminated with C. krusei, C. lusitane and C. paraplosis, respectively. While seven (16.2%) of 43 Candida spp. isolates were obtained from cheese collected from villages, 36 (83.7%) belonged to cheeses collected from traditional retail stores. The carriage rate of C. albicans isolates belonging to virulence factors HSP90 and PLB1 genes was 30.7%. ALST1, ALST3, BCR, ECE, andHWP (virulence and biofilm-associated) genes were harbored by 30.7%, 23%, 38.4%, 53.8%, and 38.4% of the 13 isolates. According to the microplate test, eight (61.5%) of 13 isolates had strong biofilm production. ERG11 and FKS1 (antifungal resistance genes) were found in 46.1% and 23% of 13 isolates, respectively. Due to missense mutations, K128T, E266D and V488I amino acid changes were detected for some isolates regarding azole resistance. As a result of the E-test, of the 13 isolates, one (7.6%) was resistant to flucytosine, four (30.7%) were resistant to caspofungin, and nine (69.2%) were resistant to fluconazole. The PCA analysis clustered the studied isolates into two major clades. C. albicans isolates of traditional cheese collected from villages were grouped in the same cluster. Among the C. albicans isolates from village cheese, there were those obtained from the same dairy milk at different times. Samples from the same sales points produced at different dairy farms were also contaminated with C. albicans. Concerning food safety standards applied from farm to fork, in order to prevent these pathogenic agents from contaminating cheeses, attention to the hygiene conditions of the sale points, conscious personnel, prevention of cross contamination will greatly reduce public health threats in addition to the application of animal health control, milking hygiene, pasteurization parameters in traditional cheese production.

Cadmium-induced augmentation of fungal translocation promotes systemic infection in mice via gut barrier disruption and immune dysfunction

Cadmium (Cd) disrupts the immune system and intestinal barrier, increasing infection risk and gut dysbiosis. Its impact on intestinal fungi, particularly the opportunistic pathogen Candida albicans, which can cause systemic infections in immunocompromised patients, is not well understood. Our study revealed that C. albicans exhibited high tolerance and maintained its morphogenetic switching in response to Cd. As C. albicans is not naturally found in the mouse gut, we attempted intestinal colonization of C. albicans-SC5314 strain using standard procedures. However, the intestinal fungal load decreased and was undetectable by 15th day. To assess the effects of sub-chronic Cd exposure, both oral and intravenous methods were used. Oral exposure to C. albicans (105 CFU/ml) resulted in a 10-fold increase in intestinal translocation in Cd-exposed mice (0.98 mg/kg) compared to controls. Cd exposure also downregulated intestinal tight junction proteins and increased FITC-dextran permeability, indicating that Cd disrupts the intestinal barrier and facilitates C. albicans translocation. Moreover, Cd-exposed mice showed significant morbidity and higher fungal loads in organs after intravenous non-lethal dose of C. albicans, along with a subdued cytokine response. These findings highlight the significant impact of Cd on fungal pathogenicity and immune response, pointing to the broader health risks of Cd exposure.

Enhanced hemocompatibility, antimicrobial and anti-inflammatory properties of biomolecules stabilized AgNPs with cytotoxic effects on cancer cells

In the current research, we developed a safe method using Iranian yarrow extract for the synthesis of silver nanoparticles (IY-AgNPs) as reducing and stabilizing agents in different conditions. The prepared and stabilized IY-AgNPs under optimal conditions were characterized using FT-IR, XRD, TEM, and UV-vis techniques. Also, the blood-clotting, hemolytic, antioxidant, bactericidal and, fungicidal properties, cytotoxicity effects and inhibition of protein denaturation efficiency of IY-AgNPs were assessed in vitro. The stabilized IY-AgNPs with spherical shape and an average particle size of 19. 25 ± 7.9 nm did not show any hemolytic potential below 1000 µg/mL. These hemo-compatible NPs showed good blood-clotting ability by reducing clotting time (6 min relative to the control). These particles excellently inhibited the denaturation of bovine serum albumin (BSA) by 69.3-80.7% at concentrations ranging from 31.25 to 500 µg/mL compared to a reference drug. The outcomes showed that the IC50 values of IY-AgNPs were below 12.5 µg/mL against A375 cells and between 25 and 50 µg/mL against MCF-7 cancer cells. In addition, IY-AgNPs were bactericidal against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus (especially), and were fungicidal against Candida albicans. Biosynthesized IY-AgNPs indicated a significant antioxidant activity (63.2%) at a concentration of 350 µg/mL. These attained results suggested that bio/hemo-compatible IY-AgNPs may be a promising candidate for applications in the medicinal fields (particularly for wound healing) as anti-bleeding, antimicrobial, antioxidant, anti-inflammatory, and anticancer agents.

Phytochemical profiling, spectroscopic identification of active compounds, and mechanism of the anticandidal properties of Datura stramonium L. using SwissADMET prediction and molecular docking analysis

BACKGROUND

Datura stramonium L., a wild-growing herb, has been traditionally used to treat various ailments, including toothache, asthma, rheumatism, epilepsy, and alopecia. Scientific evidence supports its anticancer, anti-inflammatory, anti-asthmatic, anticholinergic, antifungal, and antibacterial properties.

AIM

This study aimed to isolate, characterize, and identify the most potent anticandidal compounds inhibiting the growth of Candida spp., while also predicting their drug-likeness and toxicity profiles.

METHOD

The anticandidal activity of D. stramonium leaf extracts was assessed using the Agar well-diffusion method and minimum inhibitory concentration (MIC) was determined by the broth dilution method. The most active extract was selected for column chromatography. Different fractions were collected and screened against pathogenic Candida spp. The most active fraction was subjected to Gas chromatography-Mass spectrometry (GC-MS), Fourier Transform-Infrared Spectroscopy (FT-IR), and Nuclear Magnetic Resonance (NMR) analysis. Additionally, computational tools such as molecular docking and ADMET prediction provided further insights into the molecular interactions between the target enzymes.

RESULTS

In vitro anticandidal activity demonstrated that the ethyl acetate extract exhibited significant activity against human pathogenic Candida spp., with the highest zones of inhibition against Candida guilliermondii (20.33 ± 0.56 mm), Candida tropicalis (16.33 ± 0.58 mm), and Candida albicans (14.66 ± 1.05 mm), with a minimum inhibitory concentration (MIC) value of 25 μg/ml. Additionally, the most potent fraction (F8) obtained from the Column revealed significant anticandidal activity. GC-MS analysis of the F8 fraction indicated the presence of 23 compounds, with the major compounds being Phthalic acid, di (2-propylpentyl) ester (Compound 1), Pentadecane (Compound 2), Octadecane (Compound 3), Benzoic acid, 3-Amino-5-Hydroxy-, Methyl ester (Compound 4), and 1,2-Benzenedicarboxylic acid, bis (2-ethylhexyl) ester (Compound 5). This study reports all 23 compounds from D. stramonium for the first time. Furthermore, NMR studies confirmed the presence of Phthalic acid, di (2-propylpentyl) ester as the most abundant compound, designated as compound 1. Finally, docking analysis revealed that compound 1 showed good binding affinities for the tested enzymes, with the highest binding scores of -7.084 kcal/mol and -7.030 kcal/mol with Lanosterol 14-alpha demethylase (PDB ID: 5JLC, 5TZ1). The results of the in silico pharmacokinetic and drug-likeness properties indicated that compound 1 is a potential anticandidal drug candidate.

CONCLUSION

This study highlights that 23 compounds were reported from the leaf extract of D. stramonium for the first time. The findings suggest that compound 1 can be considered a new anticandidal drug candidate.

Exploring the anti-biofilm and gene regulatory effects of anti-inflammatory drugs on Candida albicans

Researchers have repurposed several existing anti-inflammatory drugs as potential antifungal agents in recent years. So, this study aimed to investigate the effects of anti-inflammatory drugs on the growth, biofilm formation, and expression of genes related to morphogenesis and pathogenesis in Candida albicans. The minimum inhibitory concentration (MIC) of anti-inflammatory drugs was assessed using the broth microdilution method. Biofilm formation in C. albicans was evaluated using XTT reduction assay following exposure to different concentrations of drugs. Additionally, the expression of adhesin-related genes (ALS1, ALS3), hyphal cell wall specific genes (EAP1, HWP1), secreted aspartyl proteinase (SAP4, SAP6), and morphogenesis pathway regulatory gene (EFG1) was analyzed using quantitative RT-PCR. Betamethasone and dexamethasone markedly inhibited C. albicans biofilm formation by up to 80% at a concentration of 2 mg/mL. Moreover, the inhibition of C. albicans biofilm formation was significant at concentrations ranging from 0.6 to 10 mg/mL for piroxicam and from 0.75 to 12 mg/mL for diclofenac. The expression of key genes involved in biofilm formation including EFG1, HWP1, and ALS3 was all downregulated under hyphae-inducing conditions. Moreover, the expression proteinase genes of C. albicans were upregulated following exposure with corticosteroids. The data obtained provides valuable insights into the antifungal potential of anti-inflammatory drugs. Our novel findings indicate the downregulation of several Candida genes that are crucial for morphogenesis, pathogenesis, and biofilm formation. However, further research is necessary to fully elucidate the clinical applications and effectiveness of anti-inflammatory drugs as alternative or adjunctive therapies for Candida infections.

Exploring the Biology, Virulence, and General Aspects of Candida dubliniensis

Fungal infections have become a growing public health concern, aggravated by the emergence of new pathogenic species and increasing resistance to antifungal drugs. The most common candidiasis is caused by Candida albicans; however, Candida dubliniensis has become an emerging opportunistic pathogen, and although less prevalent, it can cause superficial and systemic infections, especially in immunocompromised individuals. This yeast can colonize the oral cavity, skin, and other tissues, and has been associated with oral infections in patients with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS), making it difficult to treat. The special interest in the study of this species lies in its ability to evade commonly used antifungal drugs, such as fluconazole, under different concentrations. In addition, it is difficult to identify because it can be confused with the species C. albicans, which could interfere with adequate treatment. Although the study of virulence factors in C. dubliniensis is limited, proteomic comparisons with C. albicans indicate that these virulence factors could be similar between the two species. However, differences could exist considering the evolutionary processes and lifestyle of each species. In this study, a detailed review of the current literature on C. dubliniensis was conducted, considering aspects such as biology, possible virulence factors, immune response, pathogen-host interaction, diagnosis, and treatment.

Invasive Candidiasis

Invasive candidiasis (IC) is a term that refers to a group of infectious syndromes caused by a variety of Candida species, 6 of which cause the vast majority of cases globally. Candidemia is probably the most commonly recognized syndrome associated with IC; however, Candida species can cause invasive infection of any organ, especially visceral organs, vasculature, bones and joints, eyes, and central nervous system. The optimal use of these newer diagnostics coupled with a thoughtful clinical assessment of at-risk patients and the judicious use of effective antifungal therapy is a key to achieving good antifungal stewardship and improved patient outcomes.

Sdd3 regulates the biofilm formation of Candida albicans via the Rho1-PKC-MAPK pathway

Candida albicans, the most frequently isolated fungal pathogen in humans, forms biofilms that enhance resistance to antifungal drugs and host immunity, leading to frequent treatment failure. Understanding the molecular mechanisms governing biofilm formation is crucial for developing anti-biofilm therapies. In this study, we conducted a genetic screen to identify novel genes that regulate biofilm formation in C. albicans. One identified gene is ORF19.6693, a homolog of the Saccharomyces cerevisiae SDD3 gene. The sdd3∆/∆ mutant exhibited severe defects in biofilm formation and significantly reduced chitin content in the cell wall. Overexpression of the constitutively active version of the Rho1 GTPase Rho1G18V, an upstream activator of the protein kinase C (PKC)-mitogen-activated protein kinase (MAPK) cell-wall integrity pathway, rescued these defects. Affinity purification, mass spectrometry, and co-immunoprecipitation revealed Sdd3's physical interaction with Bem2, the GTPase-activating protein of Rho1. Deletion of SDD3 significantly reduced the amount of the active GTP-bound form of Rho1, thereby diminishing PKC-MAPK signaling and downregulating chitin synthase genes CHS2 and CHS8. Taken together, our studies identify a new biofilm regulator, Sdd3, in C. albicans that modulates Rho1 activity through its inhibitory interaction with Bem2, thereby regulating the PKC-MAPK pathway to control chitin biosynthesis, which is critical for biofilm formation. As an upstream component of the pathway and lacking a homolog in mammals, Sdd3 has the potential to serve as an antifungal target for biofilm infections.IMPORTANCEThe human fungal pathogen Candida albicans is categorized as a critical priority pathogen on the World Health Organization's Fungal Priority Pathogens List. A key virulence attribute of this pathogen is its ability to form biofilms on the surfaces of indwelling medical devices. Fungal cells in biofilms are highly resistant to antifungal drugs and host immunity, leading to treatment failure. This study conducted a genetic screen to discover novel genes that regulate biofilm formation. We found that deletion of the SDD3 gene caused severe biofilm defects. Sdd3 negatively regulates the Rho1 GTPase, an upstream activator of the protein kinase C-mitogen-activated protein kinase pathway, through direct interaction with Bem2, the GTPase-activating protein of Rho1, resulting in a significant decrease in chitin content in the fungal cell wall. This chitin synthesis defect leads to biofilm formation failure. Given its essential role in biofilm formation, Sdd3 could serve as an antifungal target for biofilm infections.

Long-chain 4-aminoquinolines inhibit filamentation and increase efficacy of nystatin against Candida albicans infections in vivo

In exploring a growing demand for innovative approaches to tackle emerging and life threatening fungal diseases, we identified long-chain 4-aminoquinoline (4-AQ) derivatives as a new class of anti-virulence agents. For the first time, we demonstrated that 4-AQs effectively prevent filamentation of Candida albicans, a key virulence trait, under multiple triggering conditions. Selected 4-AQ derivatives inhibited filament formation in a zebrafish model of disseminated candidiasis at 1.56 µM, with no toxicity up to 50 µM. Combining nystatin with 4-AQs resulted in a 100% survival rate of infected embryos and complete eradication of C. albicans, compared to 65-75% survival with nystatin alone. The most potent 4-AQ derivatives also showed significant activity against C. albicans biofilms, with derivative 11 suppressing mixed C. albicans-Pseudomonas aeruginosa biofilms. This dual capability highlights the potential of 4-AQs as novel anti-virulence agents to enhance conventional antifungal therapies, marking a significant advance in treating complex fungal infections.

Ellagic Acid Potentiates the Inhibitory Effects of Fluconazole Against Candida albicans

Background/Objectives: Antifungal resistance to azoles, coupled with the increasing prevalence of Candida albicans infections, represents a significant public health challenge and has driven the search for new natural compounds that can act as alternatives or adjuvants to the current antifungals. Ellagic acid (EA) has demonstrated antifungal activity; however, its effects are not fully understood. In this study, we investigated the in vitro anti-Candida activity of EA and its ability to potentiate the effects of fluconazole (FLZ) on C. albicans.Methods: The Minimum Inhibitory Concentration (MIC) of EA was determined by broth microdilution and its interaction with FLZ was assessed using a checkerboard assay. Additionally, we examined the effects of EA on yeast-to-hypha transition, inhibition of biofilm formation, time-kill kinetics, hemolytic activity, and cytotoxicity in HeLa ATCC® CCL-2™ cells. Results: EA exhibited MIC values ranging from 250 to 2000 µg/mL and showed synergistic and additive interactions with FLZ, resulting in a marked reduction in the MIC values of FLZ (up to 32-fold) and EA (up to 16-fold). In the time-kill assay, the most effective combinations were 4× EA MIC, 2× EA MIC, and FIC EA + FLZ, which showed fungicidal activity. Furthermore, EA did not show hemolytic activity and demonstrated low and dose-dependent cytotoxicity in HeLa cells, with no cytotoxic effects observed in combination with FLZ. EA and the synergistic combination of EA and FLZ interfered with both the yeast-to-hypha transition process in C. albicans cells and biofilm formation. In addition to its antifungal efficacy, EA demonstrated a favorable safety profile at the concentrations used. Conclusions: This study presents promising results regarding the potential use of EA in combination with FLZ for the treatment of C. albicans infections.

Evaluating the Antifungal Potential of Cinnamaldehyde: A Study of its Efficacy against Candida Species

Candida species exist as commensals in nature, colonizing the mucous membranes, gastrointestinal tract, vagina as well as the skin and usually cause infections in immunocompromised patients. C. albicans are known to be the most prevalent Candida species associated with infections, while there has been a significant surge in the incidence of Non-Candida albicans Candida species (NCAC) recently. The recent occurrences of the antifungal resistance in Candida, especially in NCAC species are quite alarming which raises the need for a safe and efficient alternative antimycotic drug. This study analyses the efficacy of cinnamaldehyde against Candida species, which is known to cause the majority of the fungal infections in humans. Cinnamaldehyde is a natural antimicrobial compound derived from cinnamon and has demonstrated significant antimycotic properties. Antifungal susceptibility profiles of cinnamaldehyde against Candida species were studied by disc diffusion as well as by broth microdilution assays. The mean diameter of the inhibition zone (IZ) formed by direct contact and disc volatilization assays were 61.26 mM and 65.20 mM, respectively. Both the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of cinnamaldehyde ranged from 16-256 mg/L with mean MIC of 60.61 mg/L and a mean MFC of 81.94 mg/L. Co-incubation of Candida cells with cinnamaldehyde resulted in the loss of viable cells within 4 hours of incubation. Cinnamaldehyde was found to exhibit both fungistatic and fungicidal properties, making it a potent natural alternative for conventional antifungal agents.

Vaginal prevention of Candida albicans: synergistic effect of lactobacilli and mannan oligosaccharides (MOS)

Vulvovaginal candidiasis (VVC) affects approximately 30-50% of women at least once during their lifetime, causing uncomfortable symptoms and limitations in their daily quality of life. Antifungal therapy is not very effective, does not prevent recurrencies and usually causes side effects. Therefore, alternative therapies are urgently needed. The goal of this work was to investigate the potential benefits of using mannan oligosaccharides (MOS) extracts together with a Lactobacillus sp. pool, composed by the most significant species present in the vaginal environment, to prevent infections by Candida albicans. Microbial growth of isolated strains of the main vaginal lactobacilli and Candida strains was assessed in the presence of MOS, to screen their impact upon growth. A pool of the lactobacilli was then tested against C. albicans in competition and prophylaxis studies; bacterial and yeast cell numbers were quantified in specific time points, and the above-mentioned studies were assessed in simulated vaginal fluid (SVF). Finally, adhesion to vaginal epithelial cells (HeLa) was also evaluated, once again resorting to simultaneous exposure (competition) or prophylaxis assays, aiming to measure the effect of MOS presence in pathogen adherence. Results demonstrated that MOS extracts have potential to prevent vaginal candidiasis in synergy with vaginal lactobacilli, with improved results than those obtained when using lactobacilli alone. KEY POINTS: Potential benefits of MOS extracts with vaginal lactobacilli to prevent C. albicans infections. MOS impacts on growth of vaginal lactobacilli pool and C. albicans in SVF. MOS extracts in synergy with L. crispatus inhibit C. albicans adhesion in HeLa cells.

Antifungal activities of Equol against Candida albicans in vitro and in vivo

Candida albicans is an opportunistic fungal pathogen that can cause systemic infections in immunocompromised individuals. Morphological transition and biofilm formation are major virulence factors of C. albicans. Moreover, biofilm enhances resistance to antifungal agents. Therefore, it is urgent to identify new and effective compounds to target the biofilm of C. albicans. In the present study, the antifungal activities of equol against C. albicans were investigated. In vitro, the microdilution analysis and spot assay result showed that equol exhibited potent inhibitory activities against C. albicans. Further investigations confirmed that the antifungal effects of equol involved interference with the transition from yeast to hypha and biofilm formation of C. albicans. In addition, transcriptome sequencing and reverse transcription-quantitative PCR (qRT-PCR) analysis showed that equol significantly downregulated the expression of several genes in the Ras1-cAMP-PKA pathway related to hyphae and biofilm formation and significantly upregulated the expression of the negative transcriptional repressors RFG1 and TUP1. Moreover, equol effectively reduced the production of cAMP, a key messenger in the Ras1-cAMP-PKA pathway, while supplementation with cAMP partly rescued the equol-induced defects in hyphal development. Furthermore, in a mouse model of systemic candidiasis (SC), equol treatment significantly decreased the fungal burden (liver, kidneys, and lung) in mice and local tissue damage, while enhancing the production of interleukin-10 (IL-10). Together, these findings confirm that equol is a potentially effective agent for treatment of SC.

Biodetection Strategies for Selective Identification of Candidiasis

Fungi are among the predominant pathogens seen in a greater proportion of infections acquired in healthcare settings. A common fungus that causes infections in medical settings is Candida species. Hospitalized patients who suffer from fungal diseases such as candidiasis and candidemia often have elevated rates of mortality and morbidity. It is evident that longer hospital stays have the possibility of bacterial and fungal recurrence and also have a negative economic impact. If left untreated, a Candida infection can spread to other organs and cause a systemic infection that can result in sepsis. Clinicians can treat patients quickly when fungal infections are timely detected, this enhances the results of clinical trials. Developing novel, sensitive, and quick methods for detecting Candida species is imperative. Conventional detection techniques are unsuitable for clinical settings and point-of-care systems as they require expensive equipment and take a longer detection time. This review examines a few of the most widely used biosensor systems for the detection of Candida species, their sensitivity, and the limit of detection. It focuses on various biorecognition elements used and follows utilization and advances in nanotechnology in the context of sensing. In addition to enabling general analysis and quick real-time analysis, crucial for detecting Candida species, biosensors provide an intriguing alternative to more conventional techniques.

Streamlined chemical fixation method for morphological investigation of Candida albicans with scanning electron microscopy

This method describes the preparation of Candida albicans specimen for scanning electron microscopy (SEM), starting from specimen collection to obtaining SEM images. Our approach involves preserving cellular structure and preventing cell degradation through chemical fixation and post-fixation without Osmium tetroxide (OsO4), followed by air dried specimen placed onto Si substrate. Additionally, the method outlines the steps for mounting the prepared specimen onto SEM sample holder aluminum stubs, followed by coating with an ultrathin gold layer via thermal evaporation to enhance specimen/substrate/stub conductivity. The specimens are then mounted in the SEM sample holder. This step-by-step procedure demonstrates successful morphological analysis of C. albicans, providing a comprehensive and effective specimen preparation for SEM analysis.•Effective preparation of Candida albicans specimens for SEM analysis, preserving cellular structure.•Step-by-step specimen mounting and gold coating for enhanced detailed SEM imaging.•Chemical fixation of yeast cells for electron microscopy visualization.

Anticandidal effect of cinnamic acid characterized from Cinnamomum cassia bark against the fluconazole resistant strains of Candida

Candida spp., causes invasive fungal infections, especially in immune-compromised patients and the propensity of antifungal resistance against azole-based drugs need to be addressed. This study is thus aimed to characterize the anticandidal effect of the cinnamic acid extracted from the barks of Cinnamomum cassia. Five species of Fluconazole-resistant Candida sp. were retrieved from the department repertoire. The extraction of CA was performed by three different methods followed by silica gel column chromatography. Eluant was subjected to FTIR and XRD analysis for confirmation. The anticandidal activity of the CA was checked by the agar disc diffusion method and the MIC and MFC were determined. The anti-biofilm effect of CA was assessed using the CLSM technique followed by the biocompatibility check using MTT assay in normal HGF cell lines. CA was best extracted with the hot maceration method using ethanol with a maximum yield of 6.73 mg. Purification by column chromatography was achieved using benzene, acetic acid, and water (6:7:3) mobile phase. CA was confirmed by FTIR with absorption peaks and by XDR based on strong intensity. CA was found to possess promising anticandidal activity at 8 µg/mL with MIC and MFC values determined as 0.8 µg/mL and 0.08 µg/mL respectively. Antibiofilm activity by CLSM analysis revealed biofilm inhibition and was biocompatible at 8.5 µg/ml concentrations in HGF cell lines until 24 h. The study findings conclude that CA is the best alternative to treat candidal infection warranting further experimental preclinical studies.

Design and synthesis of betulinic acid-dithiocarbamate conjugates as potential antifungal agents against Candida albicans

Diverse betulinic acid-dithiocarbamate conjugates were designed and synthesized via a two-step reaction at room temperature. Among the fourteen dithiocarbamate analogs of betulinic acid, DTC2 demonstrated the best antifungal activity against Candida albicans, with a minimum inhibitory concentration (MIC) of 4 μg mL-1, achieving 99% fungicidal activity at the same concentration. These compounds were found to be ineffective against common Gram-negative and Gram-positive pathogens, suggesting their specificity to fungi. Furthermore, DTC2 exhibited synergistic effects with the antifungal drugs fluconazole and nystatin, resulting in a significant decrease in MIC by 64 and 16 folds, respectively, when co-administered. Notably, the molecule also hindered hyphae formation in Candida albicans, thereby reducing its pathogenicity. Furthermore, it displayed time- and concentration-dependent kill kinetics, sterilizing C. albicans within 8 hours at 8× MIC. Additionally, DTC2 exhibits greater efficacy against β-carbonic anhydrase with better docking scores and binding patterns than ethoxyzolamide, a well-known inhibitor of β-carbonic anhydrase.

Pullulan nanoparticles inhibit the pathogenicity of Candida albicans by regulating hypha-related gene expression

Candida albicans is a prevalent opportunistic pathogenic fungus that resides in the skin and gastrointestinal (GI) tract of humans. Under specific conditions, C. albicans cells transition from a commensal to a pathogenic state, leading to both superficial and invasive infections. Although systemic candidiasis poses a life-threatening risk, a limited number of antifungal drugs are employed for its treatment. Moreover, the emergence of resistant strains to antifungal agents underscores the pressing need for new treatment options. In this study, we propose the use of polysaccharide nanoparticles as a strategy for treating candidiasis. We synthesized phthalic pullulan nanoparticles (PPNPs) and examined their ability to inhibit the pathogenicity of C. albicans. We observed that PPNPs inhibit hyphal growth, adhesion to abiotic surfaces, and biofilm formation of C. albicans in a dose-dependent manner. This inhibitory effect is mediated by transcriptional modulation, particularly the downregulation of hypha-related genes and the upregulation of stress-responsive genes, involving the Ras/cAMP/PKA signaling pathway. Furthermore, we observed that PPNPs inhibit the adhesion of C. albicans to human epithelial cells without inducing toxicity in human cells. In addition, PPNPs inhibited the in vivo pathogenicity of C. albicans in Caenorhabditis elegans, suggesting an antagonistic effect on candidiasis. Our findings suggest that PPNPs exhibit inhibitory effects on C. albicans biofilm formation and in vivo pathogenicity, indicating their potential as a novel therapeutic agent for candidiasis.

IMPORTANCE

The pathogenic process of Candida albicans, the primary causative species of candidiasis, involves hyphal growth, biofilm formation, and secretion of virulence factors. Of these factors, the biofilm, created by the secretion of extracellular matrix from adherent cells, shields cells from external threats, enabling them to withstand high concentrations of antifungal agents. Therefore, suppressing biofilm formation is a crucial aspect of combating candidiasis. This study developed phthalic pullulan nanoparticles (PPNPs) as a novel material for inhibiting C. albicans' pathogenicity. PPNPs were internalized within Candida cells and reduced pathogenicity at the gene expression level, resulting in reduced in vitro biofilm formation, adhesion to human cells, and mortality of infected Caenorhabditis elegans. Moreover, PPNPs exhibited these effects without toxicity to human cells and host animals. These findings not only indicate that PPNPs can be employed to hinder in vitro biofilm formation but also suggest their potential as a novel treatment for candidiasis.

The Effect of Xanthohumol and Thymol on Candida albicans Filamentation and Its Impact on the Structure, Size, and Cell Viability of Biofilms Developed over Implant Surfaces

The aim of this in vitro study was to evaluate the effect of xanthohumol and thymol on the impact of Candida albicans on the structure, size and cell viability of subgingival biofilms formed on dental implant surfaces. The structure and microbial biomass of biofilms developed after 72 h, treated and untreated with both extracts, were compared by scanning electron microscopy (SEM) and confocal laser microscopy (CLSM). Quantitative polymerase chain reaction (qPCR) was used to quantify the number of viable and total microorganisms of each of the biofilm-forming strains in each condition. A general linear model was used to compare and validate the CLSM and qPCR results. The presence of xanthohumol and thymol during biofilm development inhibited the filamentous growth of C. albicans. The biofilm incubated with xanthohumol had significantly lower bacterial biomass and cell viability than the biofilm not exposed to the extract (p < 0.05). In contrast, these global parameters showed no differences when the biofilm was incubated with thymol. In the presence of xanthohumol, there was a decrease in counts and cell viability of Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. Thymol treatment reduced the viability of F. nucleatum and P. gingivalis. The presence of these vegetable extracts during the development of a dynamic in vitro multispecies biofilm model inhibited the filamentous growth of C. albicans, partially reversing the effect that the fungus exerted on the structure, size and vitality of periodontopathogenic bacteria.

Comparative analysis of the postadmission and antemortem oropharyngeal and rectal swab microbiota of ICU patients

Shotgun metabarcoding was conducted to examine the microbiota in a total of 48 samples from 12 critically ill patients, analyzing samples from both the oropharynx and rectum. We aimed to compare their postadmission microbiota, characterized as moderately dysbiotic, with the severely dysbiotic antemortem microbiota associated with patients' deaths. We found that, compared with postadmission samples, patient antemortem swab samples presented moderate but not significantly decreased diversity indices. The antemortem oropharyngeal samples presented an increase in biofilm-forming bacteria, including Streptococcus oralis, methicillin-resistant Staphylococcus aureus (MRSA), and Enterococcus faecalis. Although the septic shock rate was 67%, no significant differences were detected in the potential pathogen ratios when the microbiota was analyzed. A notable strain-sharing rate between the oropharynx and intestine was noted. By comparing postadmission and antemortem samples, microbial biomarkers of severe dysbiosis were pinpointed through the analysis of differentially abundant and uniquely emerging species in both oropharyngeal and rectal swabs. Demonstrating strong interconnectivity along the oral-intestinal axis, these biomarkers could serve as indicators of the progression of dysbiosis. Furthermore, the microbial networks of the oropharyngeal microbiota in deceased patients presented the lowest modularity, suggesting a vulnerable community structure. Our data also highlight the critical importance of introducing treatments aimed at enhancing the resilience of the oral cavity microbiome, thereby contributing to better patient outcomes.

Vulvovaginal candidiasis in pregnant women attending a tertiary care centre in North-Eastern India

BACKGROUND

Candida colonisation in vagina was found to be 20 %, rising to 30 % during pregnancy. According to studies, the prevalence of VVC during pregnancy is higher than healthy women. During pregnancy, candidal colonisation increases, both symptomatic and asymptomatic. However, the difference between strains causing symptomatic infection and those that cause asymptomatic infection is unknown.

OBJECTIVE

This study aimed to compare the virulence factors of Candida VVC isolates from symptomatic and asymptomatic pregnant women.

METHODS

The study included 120 pregnant women- 60 symptomatic and 60 asymptomatic, who presented to the Obstetrics and Gynaecology Outpatient Department with vaginitis symptoms. High vaginal swabs from the patient and used for gram stain, direct wet mount, pH detection and fungal culture in SDA with and without antibiotics. Germ tube tests, growth in CMA, and HiCrome Candida Differential Agar were used to identify yeast colonies grown in culture. The isolates were then examined for virulence factors like biofilm formation, phospholipase, coagulase, and hemolysin. Antifungal susceptibility was determined using E-test.

RESULTS

The current study reveals a high prevalence of Vulvovaginal Candidiasis in pregnant women(35 %). Asymptomatic patients had lower proportion of VVC than symptomatic patients. Non albicans Candida(NAC) outnumbered Candida albicans. Although Candida albicans growth was predominant in asymptomatic patients. Virulence studies revealed that Candida spp. isolated from symptomatic patients expressed a higher proportion of virulence factors. Besides NAC has higher proportion of expressing virulence factors than Candida albicans and has higher propensity to cause infection especially in symptomatic pregnant women. Antifungal susceptibility testing shows Itraconazole to be most sensitive for VVC treatment but Candida albicans was most susceptible to fluconazole while NAC had the least.

CONCLUSIONS

The study emphasizes the importance of routine screening of symptomatic pregnant women for VVC, as syndromic treatment will increase antifungal resistance, particularly in NAC.

Novel, Speedy, and Eco-Friendly Carboxymethyl Cellulose-Nitrogen Doped Carbon Dots Biosensors with DFT Calculations, Molecular Docking, and Experimental Validation

Carboxymethyl cellulose (CMC) was prepared from sugarcane bagasse (SB) in minutes using a novel microwave method. Additionally, nitrogen-doped carbon dots (N-CDs) were synthesized from SB using the same microwave technique. These materials were crosslinked with CaCl2 to prepare antibacterial/antifungal hydrogel sensors. In this regard, both CMC@Ca and CMC@Ca-N-CDs exhibited antibacterial activity against Escherichia coli (Gram negative), while only CMC@Ca-N-CDs demonstrated antibacterial activity against Staphylococcus aureus (Gram positive). Moreover, both materials showed antifungal activity against Candida albicans. The molecular docking study demonstrated that CMC@Ca-N-CDs showed good binding with proteins with short bond length 2.59, 2.80, and 1.97 A° for Escherichia coli, Staphylococcus aureus, and Candida albicans, respectively. These binding affinities were corroborated by the observed inhibition zone diameters. Furthermore, fluorescence microscope revealed distinct imaging patterns between Gram-positive and Gram-negative bacteria, as well as pathogenic yeast (fungi). CMC@Ca-N-CDs emitted blue light when exposed to Escherichia coli and Candida albicans (i.e., CMC@Ca-N-CDs/Escherichia coli and Candida albicans), whereas it emitted bright-red light when exposed to Staphylococcus aureus (i.e., CMC@Ca-N-CDs/Staphylococcus aureus). This disparity in the fluorescence-emitted colors is due to the difference in the cell wall of these microorganisms. Additionally, DFT calculations were conducted to substantiate the robust chemical interactions between CMC, Ca2+, and N-CDs.

Anti-fungal peptides: an emerging category with enthralling therapeutic prospects in the treatment of candidiasis

Candida infections, particularly invasive candidiasis, pose a serious global health threat. Candida albicans is the most prevalent species causing candidiasis, and resistance to key antifungal drugs, such as azoles, echinocandins, polyenes, and fluoropyrimidines, has emerged. This growing multidrug resistance (MDR) complicates treatment options, highlighting the need for novel therapeutic approaches. Antifungal peptides (AFPs) are gaining recognition for their potential as new antifungal agents due to their diverse structures and functions. These natural or recombinant peptides can effectively target fungal virulence and viability, making them promising candidates for future antifungal development. This review examines infections caused by Candida species, the limitations of current antifungal treatments, and the therapeutic potential of AFPs. It emphasizes the importance of identifying novel AFP targets and their production for advancing treatment strategies. By discussing the therapeutic development of AFPs, the review aims to draw researchers' attention to this promising field. The integration of knowledge about AFPs could pave the way for novel antifungal agents with broad-spectrum activity, reduced toxicity, targeted action, and mechanisms that limit resistance in pathogenic fungi, offering significant advancements in antifungal therapeutics.

Antifungal potential of marine bacterial compounds in inhibiting Candida albicans Yck2 to overcome echinocandin resistance: a molecular dynamics study

Candida albicans (C. albicans), a common fungal pathogen, poses a significant threat to immunocompromised individuals, particularly due to the emergence of resistance against echinocandins, a primary class of antifungal agents. Yck2 protein, a key regulator of cell wall integrity and signaling pathways in C. albicans, was targeted to overcome this resistance. A virtual screening was used to identify Yck2 inhibitors from marine bacterial compounds. Further re-docking, molecular dynamics simulations, and various analyses such as root mean square deviation (RMSD), root mean square fluctuation (RMSF), hydrogen bonding, free binding energy calculations, and RG-RMSD-based free energy landscape were conducted to evaluate the efficacy and stability of the identified compounds. Among the compounds screened, CMNPD27166 and CMNPD27283 emerged as the most promising candidates, demonstrating superior binding affinities, enhanced stability, and favorable interaction dynamics with Yck2, surpassing both the control and other compounds in efficacy. In contrast, CMNPD19660 and CMNPD24402, while effective, showed lesser potential. These findings highlight the utility of computational drug discovery techniques in identifying and optimizing potential therapeutic agents and suggest that marine-derived molecules could significantly impact the development of novel antifungal therapies. Further experimental validation of the leading candidates, CMNPD27166 and CMNPD27283, is recommended to confirm their potential as effective antifungal agents against echinocandin-resistant C. albicans infections.

A novel pH-responsive monomer inhibits Candida albicans via a dual antifungal mode of action

The scarcity of the antifungal drug arsenal highlights an urgent need to develop alternative treatments for candidiasis caused by Candida albicans (C. albicans). As pH is closely associated with C. albicans infection, it could be an essential target in a novel approach for designing antifungal therapy. In this study, a novel intelligent antifungal monomer, dodecylmethylaminoethyl methacrylate (DMAEM), with a pH-responsive tertiary amine group and a methacrylate-derived CC double bond group is developed. It is uncovered that the two functional groups of DMAEM contribute to a dual mode of action. Under acidic pH, the tertiary amine of DMAEM protonates into a cationic fungicide, sharing similar structural and functional characteristics with quaternary ammonium salts, which exerts fungicidal activity by targeting the CHK1 two-component system in C. albicans. At neutral pH, the methacrylate-derived CC double bond group contributes to anti-virulence activity by blocking hyphal formation. In addition, it is also identified that DMAEM suppresses filamentation by altering the extracellular vesicles of C. albicans. These findings support that the novel intelligent pH-responsive monomer could be a therapeutic candidate for treating candidiasis.

Effect of cannabidiol (CBD), a cannabis plant derivative, against Candida albicans growth and biofilm formation

HIGHLIGHTS

Cannabidiol (CBD) decreases the growth of C. albicans. CBD inhibits the yeast-to-hyphae transition. CBD reduces biofilm formation by C. albicans. CBD induces C. albicans death through necrosis.

Expansion microscopy reveals characteristic ultrastructural features of pathogenic budding yeast species

Candida albicans is the most prevalent fungal pathogen associated with candidemia. Similar to other fungi, the complex life cycle of C. albicans has been challenging to study with high-resolution microscopy due to its small size. Here, we employed ultrastructure expansion microscopy (U-ExM) to directly visualise subcellular structures at high resolution in the yeast and during its transition to hyphal growth. N-hydroxysuccinimide (NHS)-ester pan-labelling in combination with immunofluorescence via snapshots of various mitotic stages provided a comprehensive map of nucleolar and mitochondrial segregation dynamics and enabled the resolution of the inner and outer plaque of spindle pole bodies (SPBs). Analyses of microtubules (MTs) and SPBs suggest that C. albicans displays a side-by-side SPB arrangement with a short mitotic spindle and longer astral MTs (aMTs) at the pre-anaphase stage. Modifications to the established U-ExM protocol enabled the expansion of six other human fungal pathogens, revealing that the side-by-side SPB configuration is a plausibly conserved feature shared by many fungal species. We highlight the power of U-ExM to investigate subcellular organisation at high resolution and low cost in poorly studied and medically relevant microbial pathogens.

Immunity to fungi and vaccine considerations

Fungal disease poses a growing threat to public health that our current antifungal therapies are not well equipped to meet. As the population of immunocompromised hosts expands, and ecological changes favor the emergence of fungal pathogens, the development of new antifungal agents, including vaccines, becomes a global priority. Here, we summarize recent advancements in the understanding of fungal pathogenesis, key features of the host antifungal immune response, and how these findings could be leveraged to design novel approaches to deadly fungal disease.

Candida albicans PPR proteins are required for the expression of respiratory Complex I subunits

Pentatricopeptide repeat (PPR) proteins bind RNA and are present in mitochondria and chloroplasts of Eukaryota. In fungi, they are responsible for controlling mitochondrial genome expression, mainly on the posttranscriptional level. Candida albicans is a human opportunistic pathogen with a facultative anaerobic metabolism which, unlike the model yeast Saccharomyces cerevisiae, possesses mitochondrially encoded respiratory Complex I (CI) subunits and does not tolerate loss of mtDNA. We characterized the function of 4 PPR proteins of C. albicans that lack orthologs in S. cerevisiae and found that they are required for the expression of mitochondrially encoded CI subunits. We demonstrated that these proteins localize to mitochondria and are essential to maintain the respiratory capacity of cells. Deletion of genes encoding these PPR proteins results in changes in steady-state levels of mitochondrial RNAs and proteins. We demonstrated that C. albicans cells lacking CaPpr4, CaPpr11, and CaPpr13 proteins show no CI assembly, whereas the lack of CaPpr7p results in a decreased CI activity. CaPpr13p is required to maintain the bicistronic NAD4L-NAD5 mRNA, whereas the other 3 PPR proteins are likely involved in translation-related assembly of mitochondrially encoded CI subunits. In addition, we show that CaAep3p, which is an ortholog of ScAep3p, performs the evolutionary conserved function of controlling expression of the ATP8-ATP6 mRNA. We also show that C. albicans cells lacking PPR proteins express a higher level of the inducible alternative oxidase (AOX2) which likely rescues respiratory defects and compensates for oxidative stress.

Effects of photodynamic therapy using bisdemethoxycurcumin combined with melatonin or acetyl-melatonin on C. Albicans

The current study aims to explore the efficacy of antifungal photodynamic therapy (PDT) on C. albicans biofilms by combining photosensitizers, bisdemethoxycurcumin (BDMC), and melatonin (MLT) or acetyl-melatonin (AcO-MLT). Additionally, the relationship between different types of reactive oxygen species and PDT's antifungal efficacy was investigated. BDMC, MLT and AcO-MLT were applied, alone and in combination, to 48-hour C. albicans biofilm cultures (n = 6/group). Blue and red LED light (250 mW/cm2 with 37.5 J/cm2 for single or 75 J/cm2 for dual photosensitizer groups) were used to irradiate BDMC groups and MLT/AcO-MLT groups, respectively. For combination groups, blue LEDs and subsequently red LEDs were used. Drop plate assays were performed at 0, 1 and 6 h post-treatment. Colony forming units (CFUs) were then counted after 48 h. Hydroxyl radicals and singlet oxygen were measured using fluorescence spectroscopy and electron spin resonance (ESR) spectroscopy. Additionally, cell cytotoxicity was tested on human oral keratinocytes. Significant CFU reductions were observed with combinations 20 µM BDMC + 20 µM AcO-MLT and 60 µM BDMC + 20 µM MLT at 0 and 1 h post-treatment, respectively. Singlet oxygen production increased with the addition of MLT/AcO-MLT and had moderate-substantial correlations with inhibition at all times. Hydroxyl radical production was not significantly different from the control. Additionally, BDMC exhibited subtle cytotoxicity on human oral keratinocytes. PDT using BDMC + MLT or AcO-MLT, with blue and red LED light, effectively inhibits C. albicans biofilm through singlet oxygen generation. Melatonin acts as a photosensitizer in PDT to inhibit fungal infection.

Vaginal candidiasis prevalence, associated factors, and antifungal susceptibility patterns among pregnant women attending antenatal care at bule hora university teaching hospital, Southern Ethiopia

BACKGROUND

Vulvovaginitis is common in women of reproductive age group characterized by purulent white discharge. The incidence of vulvovaginitis has risen recently due to the resistance of Candida species to commonly used antifungal agents and recurrent infections.

OBJECTIVE

The study aimed to determine the prevalence, associated factors, and antifungal susceptibility patterns of vaginal candidiasis among pregnant women attending Bule Hora University Teaching Hospital.

METHODS

A hospital-based cross-sectional study was conducted from May 2023 to August 2023. Using systematic random sampling, 317 pregnant women participated in the study. Sabouraud Dextrose Agar and Chromogenic Candida Differential Agar were used to isolate and identify Candida species from clinical samples. Antifungal susceptibility was performed using a modified disc diffusion method. Epi data version 4.6 was used for data entry and Statistical Packages for Social Sciences version 25 was used for statistical analysis. A P-value < 0.05 was declared statistically significant.

RESULT

The prevalence of vaginal candidiasis was 26.8% (95%, CI 21.9-31.72%). History of using contraceptives (AOR = 5.03, 95%CI, 1.21-11.37), past vaginal candidiasis (AOR = 6, 95%CI, 1.61-12.92), pregnant women infected with human immunodeficiency virus (HIV) (AOR = 4.24, 95%CI, 1.23-14.14), diabetic mellitus (AOR = 2.17, 95%CI, 1.02-4.64), history of antibiotic use (AOR = 3.55, 95%CI, 1.67-12.75), pregnant women in third trimester (AOR = 8.72, 95%CI, 1.30-23.07), were the significantly associated factors for vaginal candidiasis. The study revealed that itraconazole, amphotericin B, and miconazole were the most effective antifungal drugs for all Candida isolates.

CONCLUSION

The present study has identified a high prevalence of vaginal candidiasis among pregnant women. The isolated Candida species showed resistance to fluconazole, ketoconazole, and clotrimazole. Therefore, healthcare providers should increase awareness of the risks of Candida infections to reduce Candida species among pregnant women. Physicians should prescribe suitable medications based on antifungal drug test outcomes to treat pregnant women with vaginal candidiasis.

Studies on the antifungal effects of Hinokitiol on Candida albicans: inhibition of germ tube formation and synergistic pharmacological effects of miconazole

One of the goals of oral healthcare management is to manage dry mouth. Thus, moisturizers containing antimicrobial ingredients, such as hinokitiol (HT), are applied to the oral mucosa after oral care. In this study, we investigated the preventive effect of HT against the growth of Candida albicans (C. al) and its synergistic effect when combined with miconazole (MCZ), an oral treatment for candidiasis. As the concentration of HT increased, the length and percentage of germ tubes (GT) decreased. Larger inhibition circles were observed for MCZ concentrations of 2.0 and 4.0 μg/disc compared to the HT medium without HT. The increased inhibitory effect was observed in both aerobic and anaerobic cultures. This suggests that the production of reactive oxygen species (ROS) by C. al cells increased with the combination of HT and MCZ. The length and percentage of GT increased, whereas the amount of ROS decreased when ROS scavengers were used in combination with the drug. HT led to morphological changes that inhibited the GT associated with pathogenic C. al, exhibited a complementary action against MCZ, and showed a possible association with hydrogen peroxide and superhydroxy anion radicals. These effects suggest that HT is a promising candidate for inhibiting C. al. In conclusion, HT demonstrated a prophylactic effect by inhibiting C. al and a synergistic effect with MCZ, a drug used to treat oral candidiasis. HT may also be useful for suppressing the onset and reducing the severity of oral candidiasis.

Non-canonical IL-22 receptor signaling remodels the mucosal barrier during fungal immunosurveillance

Mucosal barrier integrity is vital for homeostasis with commensal organisms while preventing pathogen invasion. We unexpectedly found that fungal-induced immunosurveillance enhances resistance to fungal outgrowth and tissue invasion by remodeling the oral mucosal epithelial barrier in mouse models of adult and neonatal Candida albicans colonization. Epithelial subset expansion and tissue remodeling were dependent on interleukin-22 (IL-22) and signal transducer and activator of transcription 3 (STAT3) signaling, through a non-canonical receptor complex composed of glycoprotein 130 (gp130) coupled with IL-22RA1 and IL-10RB. Immunosurveillance-induced epithelial remodeling was restricted to the oral mucosa, whereas barrier architecture was reset once fungal-specific immunity developed. Collectively, these findings identify fungal-induced transient mucosal remodeling as a critical determinant of resistance to mucosal fungal infection during early stages of microbial colonization.

A Brg1-Rme1 circuit in Candida albicans hyphal gene regulation

Major Candida albicans virulence traits include its ability to make hyphae, to produce a biofilm, and to damage host cells. These traits depend upon expression of hypha-associated genes. A gene expression comparison among clinical isolates suggested that transcription factor Rme1, established by previous studies to be a positive regulator of chlamydospore formation, may also be a negative regulator of hypha-associated genes. Engineered RME1 overexpression supported this hypothesis, but no relevant rme1Δ/Δ mutant phenotype was detected. We reasoned that Rme1 may function within a specific regulatory pathway. This idea was supported by our finding that an rme1Δ/Δ mutation relieves the need for biofilm regulator Brg1 in biofilm formation. The impact of the rme1Δ/Δ mutation is most prominent under static or "biofilm-like" growth conditions. RNA sequencing (RNA-seq) of cells grown under biofilm-like conditions indicates that Brg1 activates hypha-associated genes indirectly via repression of RME1: hypha-associated gene expression levels are substantially reduced in a brg1Δ/Δ mutant and partially restored in a brg1Δ/Δ rme1Δ/Δ double mutant. An rme1Δ/Δ mutation does not simply bypass Brg1, because iron homeostasis genes depend upon Brg1 regardless of Rme1. Rme1 thus connects Brg1 to the targets relevant to hypha and biofilm formation under biofilm growth conditions.IMPORTANCECandida albicans is a major fungal pathogen of humans, and its ability to grow as a surface-associated biofilm on implanted devices is a common cause of infection. Here, we describe a new regulator of biofilm formation, RME1, whose activity is most prominent under biofilm-like growth conditions.

Exploring Extremotolerant and Extremophilic Microalgae: New Frontiers in Sustainable Biotechnological Applications

Exploring extremotolerant and extremophilic microalgae opens new frontiers in sustainable biotechnological applications. These microorganisms thrive in extreme environments and exhibit specialized metabolic pathways, making them valuable for various industries. The study focuses on the ecological adaptation and biotechnological potential of these microalgae, highlighting their ability to produce bioactive compounds under stress conditions. The literature reveals that extremophilic microalgae can significantly enhance biomass production, reduce contamination risks in large-scale systems, and produce valuable biomolecules such as carotenoids, lipids, and proteins. These insights suggest that extremophilic microalgae have promising applications in food, pharmaceutical, cosmetic, and biofuel industries, offering sustainable and efficient alternatives to traditional resources. The review concludes that further exploration and utilization of these unique microorganisms can lead to innovative and environmentally friendly solutions in biotechnology.

Effectiveness of Lemon Verbena (Cymbopogon citratus) in Oral Candidiasis: A Systematic Review

The rise of phytotherapy has enabled the utilization of various plant species for medicinal purposes, such as Cymbopogon citratus (C. citratus), providing solutions for oral pathologies, such as oral candidiasis. The PubMed, Web of Science, Scopus, and SciELO databases were searched. In vivo and in vitro studies on the action of C. citratus against oral candidiasis were included, and ROBINS-I was used to determine study quality and risk of bias. The search yielded 1922 articles, of which 10 met the inclusion criteria. Limited scientific evidence exists regarding the use of C. citratus for oral candidiasis. However, studies have indicated its potent antifungal effects. Further studies, preferably clinical trials, are necessary to confirm this effect and to enable its clinical use as a therapeutic option.

Cluster analysis allowed to identify antifungal drugs that retain efficacy against Candida albicans isolated from patients with inflammatory diseases of the soft tissues of the maxillofacial area

Physicians are increasingly prescribing antifungal drugs empirically to treat hospital-acquired infections quickly. This makes it obvious that fungal infections require more attention and systematic monitoring of resistance among them. The aim of the study was to identify antifungal drugs that retain their efficacy against C. albicans isolates. There were 17 clinical isolates of Candida albicans obtained from patients and tested for susceptibility to antifungal drugs using the standard double dilution method. Amphotericin B, fluconazole, itraconazole, micafungin, and posaconazole were used in the study. To determine the groups of antimycotics to which the studied microorganisms retain sensitivity, a hierarchical cluster analysis was performed using the Ward's method. The tested representatives of the genus Candida showed the lowest sensitivity to fluconazole. The efficacy of amphotericin B and itraconazole was almost at the same level. In turn, micafungin and posaconazole showed the best results against C. albicans isolates. Ward's cluster analysis combined the results of C. albicans susceptibility to fluconazole, micafungin and itraconazole by the highest mathematical similarity. Amphotericin B and posaconazole were combined into one cluster due to their better efficacy against Candida albicans isolates.

Evaluation of adherence of Candida albicans to differently manufactured acrylic resin denture base materials

STATEMENT OF PROBLEM

Though computer-aided design and computer-aided manufactured (CAD-CAM) denture bases have become popular, evidence on the ability of C. albicans cells to adhere to these denture bases is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the adherence of Candida albicans to differently manufactured acrylic resin denture bases.

MATERIAL AND METHODS

Acrylic resin disks were fabricated using a total of 6 different fabrication methods (compression molding, injection molding, CAD-CAM milling, and rapid prototyping on 3 different printers with 3 different resins). Each material was evaluated for adherence of C. albicans using 2 different experimental methods - suspension in inoculated tryptic soy broth (TSB) or placed onto a uniform lawn of C. albicans on tryptone soya agar (TSA) with 5% sheep's blood. Attached cells were quantified by spiral plating and then used to re-inoculate sterile plates. Logarithmic transformation was completed to normalize data. For the broth suspension, the Kruskal-Wallis test was used to identify any differences between the 6 specimen types in terms of recovery, and the Dunn test was used for post hoc analysis. For the microbial lawn experiment, 1-way analysis of variance (ANOVA) and then the Tukey Honestly Significant Difference (HSD) post hoc test were used.

RESULTS

Statistically significant differences were found between the numbers of adherent cells based on manufacturing method and between experimental designs (P<.05). All resins demonstrated growth with re-inoculation.

CONCLUSIONS

Though statistical significance was noted, neither experimental technique demonstrated what is likely a clinically significant preferential binding to any particular resin surface. Attached Candida cells are effective carriers of pathogens to uninfected surfaces. Further studies are indicated for potential virulence factors and differences in printed resins.

H3K56 acetylation affects Candida albicans morphology and secreted soluble factors interacting with the host

In recent years, epigenetics has been revealed as a mechanism able to modulate the expression of virulence traits in diverse pathogens, including Candida albicans. Indeed, epigenetic regulation can sense environmental changes, leading to the rapid and reversible modulation of gene expression with consequent adaptation to novel environments. How epigenetic changes can impact expression and signalling output, including events associated with mechanisms of morphological transition and virulence, is still poorly studied. Here, using nicotinamide as a sirtuin inhibitor, we explored how the accumulation of the H3K56 acetylation, the most prominent histone acetylation in C. albicans, might affect its interaction with the host. Our experiments demonstrate that H3K56 acetylation profoundly affects the production and/or secretion of soluble factors compromising actin remodelling and cytokine production. ChIP- and RNA-seq analyses highlighted a direct impact of H3K56 acetylation on genes related to phenotypic switching, biofilm formation and cell aggregation. Direct and indirect regulation also involves genes related to cell wall protein biosynthesis, β-glucan and mannan exposure, and hydrolytic secreted enzymes, supporting the hypothesis that the fluctuations of H3K56 acetylation in C. albicans might impair the macrophage response to the yeast and thus promote the host-immune escaping.

Oral Microbiome: A Review of Its Impact on Oral and Systemic Health

PURPOSE OF REVIEW

This review investigates the oral microbiome's composition, functions, influencing factors, connections to oral and systemic diseases, and personalized oral care strategies.

RECENT FINDINGS

The oral microbiome is a complex ecosystem consisting of bacteria, fungi, archaea, and viruses that contribute to oral health. Various factors, such as diet, smoking, alcohol consumption, lifestyle choices, and medical conditions, can affect the balance of the oral microbiome and lead to dysbiosis, which can result in oral health issues like dental caries, gingivitis, periodontitis, oral candidiasis, and halitosis. Importantly, our review explores novel associations between the oral microbiome and systemic diseases including gastrointestinal, cardiovascular, endocrinal, and neurological conditions, autoimmune diseases, and cancer. We comprehensively review the efficacy of interventions like dental probiotics, xylitol, oral rinses, fluoride, essential oils, oil pulling, and peptides in promoting oral health by modulating the oral microbiome.

SUMMARY

This review emphasizes the critical functions of the oral microbiota in dental and overall health, providing insights into the effects of microbial imbalances on various diseases. It underlines the significant connection between the oral microbiota and general health. Furthermore, it explores the advantages of probiotics and other dental care ingredients in promoting oral health and addressing common oral issues, offering a comprehensive strategy for personalized oral care.

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 β-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.

Exploring the Antimicrobial Potential of Hallachrome, a Defensive Anthraquinone from the Marine Worm Halla parthenopeia (Polychaeta)

Antimicrobial resistance is a critical global health issue, with rising resistance among bacteria and fungi. Marine organisms have emerged as promising, but underexplored, sources of new antimicrobial agents. Among them, marine polychaetes, such as Halla parthenopeia, which possess chemical defenses, could attract significant research interest. This study explores the antimicrobial properties of hallachrome, a unique anthraquinone found in the purple mucus of H. parthenopeia, against Gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 9027), Gram-positive bacteria (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228), and the most common human fungal pathogen Candida albicans ATCC 10231. Antibacterial susceptibility testing revealed that Gram-negative bacteria were not inhibited by hallachrome at concentrations ≤2 mM. However, Gram-positive bacteria showed significant growth inhibition at 0.12-0.25 mM, while C. albicans was inhibited at 0.06 mM. Time-kill studies demonstrated dose-dependent growth inhibition of susceptible strains by hallachrome, which exerted its effect by altering the membrane permeability of C. albicans, E. faecalis, and S. epidermidis after 6 h and S. aureus after 24 h. Additionally, hallachrome significantly reduced biofilm formation and mature biofilm in S. aureus, E. faecalis, and C. albicans. Additionally, it inhibited hyphal growth in C. albicans. These findings highlight hallachrome's potential as a novel antimicrobial agent, deserving further exploration for clinical experimentation.

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.

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.

Deletion of the Candida albicans TLO gene family results in alterations in membrane sterol composition and fluconazole tolerance

Development of resistance and tolerance to antifungal drugs in Candida albicans can compromise treatment of infections caused by this pathogenic yeast species. The uniquely expanded C. albicans TLO gene family is comprised of 14 paralogous genes which encode Med2, a subunit of the multiprotein Mediator complex which is involved in the global control of transcription. This study investigates the acquisition of fluconazole tolerance in a mutant in which the entire TLO gene family has been deleted. This phenotype was reversed to varying degrees upon reintroduction of representative members of the alpha- and beta-TLO clades (i.e. TLO1 and TLO2), but not by TLO11, a gamma-clade representative. Comparative RNA sequencing analysis revealed changes in the expression of genes involved in a range of cellular functions, including ergosterol biosynthesis, mitochondrial function, and redox homeostasis. This was supported by the results of mass spectrometry analysis, which revealed alterations in sterol composition of the mutant cell membrane. Our data suggest that members of the C. albicans TLO gene family are involved in the control of ergosterol biosynthesis and mitochondrial function and may play a role in the responses of C. albicans to azole antifungal agents.

Cortactin: A major cellular target of viral, protozoal, and fungal pathogens

Many viral, protozoal, and fungal pathogens represent major human and animal health problems due to their great potential of causing infectious diseases. Research on these pathogens has contributed substantially to our current understanding of both microbial virulence determinants and host key factors during infection. Countless studies have also shed light on the molecular mechanisms of host-pathogen interactions that are employed by these microbes. For example, actin cytoskeletal dynamics play critical roles in effective adhesion, host cell entry, and intracellular movements of intruding pathogens. Cortactin is an eminent host cell protein that stimulates actin polymerization and signal transduction, and recently emerged as fundamental player during host-pathogen crosstalk. Here we review the important role of cortactin as major target for various prominent viral, protozoal and fungal pathogens in humans, and its role in human disease development and cancer progression. Most if not all of these important classes of pathogens have been reported to hijack cortactin during infection through mediating up- or downregulation of cortactin mRNA and protein expression as well as signaling. In particular, pathogen-induced changes in tyrosine and serine phosphorylation status of cortactin at its major phospho-sites (Y-421, Y-470, Y-486, S-113, S-298, S-405, and S-418) are addressed. As has been reported for various Gram-negative and Gram-positive bacteria, many pathogenic viruses, protozoa, and fungi also control these regulatory phospho-sites, for example, by activating kinases such as Src, PAK, ERK1/2, and PKD, which are known to phosphorylate cortactin. In addition, the recruitment of cortactin and its interaction partners, like the Arp2/3 complex and F-actin, to the contact sites between pathogens and host cells is highlighted, as this plays an important role in the infection process and internalization of several pathogens. However, there are also other ways in which the pathogens can exploit the function of cortactin for their needs, as the cortactin-mediated regulation of cellular processes is complex and involves numerous different interaction partners. Here, the current state of knowledge is summarized.

The wound microbiota: microbial mechanisms of impaired wound healing and infection

The skin barrier protects the human body from invasion by exogenous and pathogenic microorganisms. A breach in this barrier exposes the underlying tissue to microbial contamination, which can lead to infection, delayed healing, and further loss of tissue and organ integrity. Delayed wound healing and chronic wounds are associated with comorbidities, including diabetes, advanced age, immunosuppression and autoimmune disease. The wound microbiota can influence each stage of the multi-factorial repair process and influence the likelihood of an infection. Pathogens that commonly infect wounds, such as Staphylococcus aureus and Pseudomonas aeruginosa, express specialized virulence factors that facilitate adherence and invasion. Biofilm formation and other polymicrobial interactions contribute to host immunity evasion and resistance to antimicrobial therapies. Anaerobic organisms, fungal and viral pathogens, and emerging drug-resistant microorganisms present unique challenges for diagnosis and therapy. In this Review, we explore the current understanding of how microorganisms present in wounds impact the process of skin repair and lead to infection through their actions on the host and the other microbial wound inhabitants.