Candida albicans biofilms: development, regulation, and molecular mechanisms

Nanomaterial-based therapeutics for enhanced antifungal therapy

The application of nanotechnology in antifungal therapy is gaining increasing attention. Current antifungal drugs have significant limitations, such as severe side effects, low bioavailability, and the rapid development of resistance. Nanotechnology offers an innovative solution to address these issues. This review discusses three key strategies of nanotechnology to enhance antifungal efficacy. Firstly, nanomaterials can enhance their interaction with fungal cells via ingenious surface tailoring of nanomaterials. Effective adhesion of nanoparticles to fungal cells can be achieved by electrostatic interaction or specific targeting to the fungal cell wall and cell membrane. Secondly, stimuli-responsive nanomaterials are developed to realize smart release of drugs in the specific microenvironment of pathological tissues, such as the fungal biofilm microenvironment and inflammatory microenvironment. Thirdly, nanomaterials can be designed to cross different physiological barriers, effectively addressing challenges posed by skin, corneal, and blood-brain barriers. Additionally, some new nanomaterial-based strategies in treating fungal infections are discussed, including the development of fungal vaccines, modulation of macrophage activity, phage therapy, the application of high-throughput screening in drug discovery, and so on. Despite the challenges faced in applying nanotechnology to antifungal therapy, its significant potential and innovation open new possibilities for future clinical antifungal applications.

In silico-driven identification and experimental confirmation of antifungal proteins (AFPs) against Candidaalbicans

Mycoses infect millions of people annually across the world. The most common mycosis agent, Candida albicans is responsible for a great deal of illness and death. C. albicans infection is becoming more widespread and the current antifungals polyenes, triazoles, and echinocandins are less efficient against it. Investigating antifungal peptides (AFPs) as therapeutic is gaining momentum. Therefore, we used MALDI-TOF/MS analysis to identify AFPs and protein-protein docking to analyze their interactions with the C. albicans target protein. Some microorganisms with strong antifungal action against C. albicans were selected for the isolation of AFPs. Using MALDI-TOF/MS, we identified 3 AFPs Chitin binding protein (ACW83017.1; Bacillus licheniformis), the bifunctional protein GlmU (BBQ13478.1; Stenotrophomonas maltophilia), and zinc metalloproteinase aureolysin (BBA25172.1; Staphylococcus aureus). These AFPs showed robust interactions with C. albicans target protein Sap5. We deciphered some important residues in identified APFs and highlighted interaction with Sap5 through hydrogen bonds, protein-protein interactions, and salt bridges using protein-protein docking and MD simulations. The three discovered AFPs-Sap5 complexes exhibit different levels of stability, as seen by the RMSD analysis and interaction patterns. Among protein-protein interactions, the remarkable stability of the BBQ25172.1-2QZX complex highlights the role of salt bridges and hydrogen bonds. Identified AFPs could be further studied for developing successful antifungal candidates and peptide-based new antifungal therapeutic strategies as fresh insights into addressing antifungal resistance also.

Evaluation of antifungal spectrum of Cupferron against Candida albicans

Candida albicans is an opportunistic yeast accounting for about 50-90 % of all cases of candidiasis in humans, ranging from superficial to systemic potentially life-threatening infections. The presence of several virulence factors, including biofilm, hyphal transition, and proteolytic enzymes production, worsens the fungal infections burden on healthcare system resources. Hence, developing new bioactive compounds with antifungal activity is a pressing urgence for the scientific community. In this perspective, we evaluated the anti-Candida potential of the N-Nitroso-N-phenylhydroxylamine ammonium salt (cupferron) against standard and clinical C. albicans strains. Firstly, the in vitro cytotoxicity of cupferron was checked in the range 400-12.5 μg/mL against human microglial cells (HMC-3). Secondly, its antifungal spectrum was explored via disk diffusion test, broth-microdilution method, and time-killing curve analysis, validating the obtained results through scanning electron microscopy (SEM) observations. Additionally, we evaluated the cupferron impact on the main virulence determinants of Candida albicans. At non-toxic concentrations (100-12.5 μg/mL), the compound exerted interesting anti-Candida activity, registering a minimum inhibitory concentration (MIC) between 50 and 100 μg/mL against the tested strains, with a fungistatic effect until 100 μg/mL. Furthermore, cupferron was able to counteract fungal virulence at MIC and sub-MIC values (50-12.5 μg/mL). These findings may propose cupferron as a new potential antifungal option for the treatment of Candida albicans infections.

ASLdC3: A Derivative of Acidic Sophorolipid Disrupts Mitochondrial Function, Induces ROS Generation, and Inhibits Biofilm Formation in Candida albicans

Fungal infections account for more than 140 million cases of severe and life-threatening conditions each year, causing approximately 1.7 million deaths annually. Candida albicans and related species are the most common human fungal pathogens, causing both superficial (mucosal and cutaneous) and life-threatening invasive infections (candidemia) with a 40-75% mortality rate. Among many virulence factors of Candida albicans, morphological transition from yeast to hyphae, secretion of hydrolytic enzymes, and formation of biofilms are considered to be crucial for pathogenicity. However, the arsenals for the treatment against these pathogens are restricted to only a few classes of approved drugs, the efficacy of which is being compromised by host toxicity, fungistatic activity, and the emergence of drug resistance. In this study, we have described the development of a molecule, exhibiting excellent antifungal activity (MIC 8 μg/mL), by tailoring acidic sophorolipids with aryl alcohols via enzyme catalysis. This novel derivative, ASLdC3, is a surface-active compound that lowers the surface tension of the air-water interface up to 2-fold before reaching the critical micelle concentration of 25 μg/mL. ASLdC3 exhibits excellent antibiofilm properties against Candida albicans and other nonalbicans Candida species. The molecule primarily exhibits its antifungal activity by perturbing mitochondrial function through the alteration of the mitochondrial membrane potential (MMP) and generation of reactive oxygen species (ROS). The ROS damages fungal cell membrane function and cell wall integrity, eventually leading to cell death. ASLdC3 was found to be nontoxic in in vitro assay and nonhemolytic. Besides, it does not cause toxicity in the C. elegans model. Our study provides a valuable foundation for the potential of acidic sophorolipid as a nontoxic, biodegradable precursor for the design and synthesis of novel molecules for use as antimicrobial drugs as well as for other clinical applications.

Nanoformulations for dismantling fungal biofilms: The latest arsenals of antifungal therapy

Globally, fungal infections have evolved as a strenuous challenge for clinicians, particularly in patients with compromised immunity in intensive care units. Fungal co-infection in Covid-19 patients has made the situation more formidable for healthcare practitioners. Surface adhered fungal population known as biofilm often develop at the diseased site to elicit antifungal tolerance and recalcitrant traits. Thus, an innovative strategy is required to impede/eradicate developed biofilm and avoid the formation of new colonies. The development of nanocomposite-based antibiofilm solutions is the most appropriate way to withstand and dismantle biofilm structures. Nanocomposites can be utilized as a drug delivery medium and for fabrication of anti-biofilm surfaces capable to resist fungal colonization. In this context, the present review comprehensively described different forms of nanocomposites and mode of their action against fungal biofilms. Amongst various nanocomposites, efficacy of metal/organic nanoparticles and nanofibers are particularly emphasized to highlight their role in the pursuit of antibiofilm strategies. Further, the inevitable concern of nanotoxicology has also been introduced and discussed with the exigent need of addressing it while developing nano-based therapies. Further, a list of FDA-approved nano-based antifungal formulations for therapeutic usage available to date has been described. Collectively, the review highlights the potential, scope, and future of nanocomposite-based antibiofilm therapeutics to address the fungal biofilm management issue.

Kinetics characterization of a low immunogenic recombinant l-asparaginase from Phaseolus vulgaris with cytotoxic activity against leukemia cells

l-asparaginases play a crucial role in the treatment of acute lymphoblastic leukemia (ALL), a type of cancer that mostly affects children and teenagers. However, it is common for these molecules to cause adverse reactions during treatment. These downsides ignite the search for novel asparaginases to mitigate these problems. Thus, this work aimed to produce and characterize a recombinant asparaginase from Phaseolus vulgaris (Asp-P). In this study, Asp-P was expressed in Escherichia coli with high yields and optimum activity at 40 °C, pH 9.0. The enzyme Km and Vmax values were 7.05 mM and 1027 U/mg, respectively. Asp-P is specific for l-asparagine, showing no activity against l-glutamine and other amino acids. The enzyme showed a higher cytotoxic effect against Raji than K562 cell lines, but only at high concentrations. In silico analysis indicated that Asp-P has lower immunogenicity than a commercial enzyme. Asp-P induced biofilm formation by Candida sp. due to sublethal dose, showing an underexplored potential of asparaginases. The absence of glutaminase activity, lower immunogenicity and optimal activity similar to physiological temperature conditions are characteristics that indicate Asp-P as a potential new commercial enzyme in the treatment of ALL and its underexplored application in the treatment of other diseases.

Bioinspired ferromagnetic NiFe2O4 nanoparticles: Eradication of fungal and drug-resistant bacterial pathogens and their established biofilm

Nickel ferrite nanoparticles (NiFe2O4 NPs) were synthesized using the medicinally important plant Aloe vera leaf extract, and their structural, morphological, and magnetic properties were characterized by x-ray diffraction (XRD), fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and vibrating sample magnetometer (VSM). The synthesized NPs were soft ferromagnetic and spinel in nature, with an average particle size of 22.2 nm. To the best of our understanding, this is the first comprehensive investigation into the antibacterial, anticandidal, antibiofilm, and antihyphal properties of NiFe2O4 NPs against C. albicans as well as drug-resistant gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and gram-negative multidrug resistant Pseudomonas aeruginosa (MDR-P. aeruginosa) bacteria. NiFe2O4 NPs showed potent antimicrobial activity (MIC 1.6-2 mg/mL) against the test pathogens. NiFe2O4 NPs at 0.5 mg/mL suppressed biofilm formation by 49.5-53.1 % in test pathogens. The study found that the NPs not only prevent the formation of biofilm, but also eliminate existing mature biofilms by 50.5-75.79 % at 0.5 mg/mL, which was further validated by SEM. SEM examination revealed a reduction in the number of cells that form biofilms and adhere to the surface. Additionally, it considerably impeded the colonization and aggregation of the biofilm strains on the glass surface. Light microscopic examination demonstrated that NPs effectively prevent the expansion of hyphae, filaments, and yeast-to-hyphae transformation in C. albicans, resulting in a substantial decrease in their ability to cause infection. Moreover, SEM images of the treated cells exhibited the presence of wrinkles, deformities, and impaired cell walls, which suggests an alteration and instability of the membrane. This study demonstrated the efficacy of the greenly manufactured NPs in suppressing the proliferation of candida, drug-resistant bacteria, and their preexisting biofilms, as well as yeast-to-hyphae transformation. Therefore, these NPs with broad spectrum applications could be utilized in health settings to mitigate biofilm-related health conditions caused by pathogenic microbial strains.

Improvement of a low-cost protocol for a simultaneous comparative evaluation of hydrolytic activity between sessile and planktonic cells: Candida albicans as a study model

Candida albicans is often implicated in nosocomial infections with fatal consequences. Its virulence is contributed to hydrolytic enzymes and biofilm formation. Previous research focused on studying these virulence factors individually. Therefore, this study aimed to investigate the impact of biofilm formation on the hydrolytic activity using an adapted low-cost method. Eleven strains of C. albicans were used. The biofilms were formed on pre-treated silicone discs using 24-well plates and then deposited on the appropriate agar to test each enzyme, while the planktonic cells were conventionally seeded. Biofilms were analysed using Raman spectroscopy, fluorescent and scanning electron microscopy. The adapted method provided an evaluation of hydrolytic enzymes activity in C. albicans biofilm and showed that sessile cells had a higher phospholipase and proteinase activities compared with planktonic cells. These findings were supported by spectroscopic and microscopic analyses, which provided valuable insights into the virulence mechanisms of C. albicans during biofilm formation.

New arsenals for old armour: Biogenic nanoparticles in the battle against drug-resistant Candidaalbicans

Candida albicans is a common commensal fungus and fourth most frequent causative agent of nosocomial infections including life-threatening invasive candidiasis in humans. The effectiveness of present antifungal therapies using azoles, polyenes, flucytosine and echinocandins has plateaued in managing fungal infections. The limitations of these antifungal drugs are related to polymorphic morphology, biofilm formation, emergence of drug-resistant strains and production of several virulence factors. Development of new antifungal agents, which can particularly afflict multiple cellular targets and limiting evolving resistant strains are needed. Recently, metal nanoparticles have emerged as a source of new antifungal agents for antifungal formulations. Furthermore, green nanotechnology deals with the use of biosynthetic routes that offer new avenue for synthesizing antifungal nanoparticles coupled with less toxic chemical inventory and environmental sustainability. This article reviews the recent developments on C. albicans pathogenesis, biofilm formation, drug resistance, mode of action of antifungal drugs and antifungal activities of metal nanoparticles. The antifungal efficacy and mode of action of metal nanoparticles are described in the context of prospective therapeutic applications.

LC-MS/MS profiling and analysis of Bacillus licheniformis extracellular proteins for antifungal potential against Candida albicans

Candida albicans, a significant human pathogenic fungus, employs hydrolytic proteases for host invasion. Conventional antifungal agents are reported with resistance issues from around the world. This study investigates the role of Bacillus licheniformis extracellular proteins (ECP) as effective antifungal peptides (AFPs). The aim was to identify and characterize the ECP of B. licheniformis through LC-MS/MS and bioinformatics analysis. LC-MS/MS analysis identified 326 proteins with 69 putative ECP, further analyzed in silico. Of these, 21 peptides exhibited antifungal properties revealed by classAMP tool and are predominantly anionic. Peptide-protein docking revealed interactions between AFPs like Peptide chain release factor 1 (Q65DV1_Seq1: SASEQLSDAK) and Putative carboxy peptidase (Q65IF0_Seq7: SDSSLEDQDFILESK) with C. albicans virulent SAP5 proteins (PDB ID 2QZX), forming hydrogen bonds and significant Pi-Pi interactions. The identification of B. licheniformis ECP is the novelty of the study that sheds light on their antifungal potential. The identified AFPs, particularly those interacting with bonafide pharmaceutical targets SAP5 of C. albicans represent promising avenues for the development of antifungal treatments with AFPs that could be the pursuit of a novel therapeutic strategy against C. albicans. SIGNIFICANCE OF STUDY: The purpose of this work was to carry out proteomic profiling of the secretome of B. licheniformis. Previously, the efficacy of Bacillus licheniformis extracellular proteins against Candida albicans was investigated and documented in a recently communicated manuscript, showcasing the antifungal activity of these proteins. In order to achieve high-throughput identification of ES (Excretory-secretory) proteins, the utilization of liquid chromatography tandem mass spectrometry (LC-MS) was utilized. There was a lack of comprehensive research on AFPs in B. licheniformis, nevertheless. The proteins secreted by B. licheniformis in liquid medium were initially discovered using liquid chromatography-tandem mass spectrometry (LC-MS) analysis and identification in order to immediately characterize the unidentified active metabolites in fermentation broth.

Fleagrass (Adenosma buchneroides Bonati) Acts as a Fungicide Against Candida albicans by Damaging Its Cell Wall

Fleagrass, a herb known for its pleasant aroma, is widely used as a mosquito repellent, antibacterial agent, and for treating colds, reducing swelling, and alleviating pain. The antifungal effects of the essential oils of fleagrass and carvacrol against Candida albicans were investigated by evaluating the growth and the mycelial and biofilm development of C. albicans. Transmission electron microscopy was used to evaluate the integrity of the cell membrane and cell wall of C. albicans. Fleagrass exhibited high fungicidal activity against C. albicans at concentrations of 0.5% v/v (via the Ras1/cAMP/PKA pathway). Furthermore, transmission electron microscopy revealed damage to the cell wall and membrane after treatment with the essential oil, which was further confirmed by the increased levels of β-1,3-glucan and chitin in the cell wall. This study showed that fleagrass exerts good fungicidal and hyphal growth inhibition activity against C. albicans by disrupting its cell wall, and thus, fleagrass may be a potential antifungal drug.

Biofilm Formation on Denture Base Material Reinforced With a Novel Organic Material

BACKGROUND

Microcrystalline cellulose (MCC) is a novel organic material developed by one of the authors in this study. When MCC was incorporated with conventionally available denture base resin, it demonstrated increased flexural strength and flexural modulus. However, it was speculated that because the material is organic, it can promote the growth of Candida. The purpose of this study is to evaluate the Candida albicans biofilm formation on polymethyl methacrylate (PMMA) denture base resin incorporated with MCC.

MATERIALS AND METHODS

MCC is an organic material extracted from the oil palm empty fruit bunch (OPEFB). The growth of C. albicans and biofilm formation in three test groups were compared by biofilm assay and imaging techniques like microscopy (by safranin staining) and scanning electron microscopy. The three test groups were comprised of MCC-reinforced PMMA containing OPEFB fibers of 50-micrometer thickness at 5% weight reinforcement, conventionally and commercially available heat cure PMMA, and an empty well to assess any discrepancies from the environment.

RESULTS

The test groups showed increased biofilm formation by C. albicans compared to commercially and conventionally available heat cure PMMA. Reinforcement with MCC showed higher biofilm formation of 1.43 times higher compared to conventional PMMA. Biofilms formed by Candida albicans on MCC-reinforced PMMA appeared heterogeneous in structure, comprised of yeast cells and hyphae, surrounded by a higher density of polysaccharide extracellular matrix material compared to that of conventionally available heat cure PMMA.

CONCLUSION

Biofilm formation is increased in denture base resin incorporated with MCC. More investigation is warranted to study the antifungal efficacy of the addition of antifungal agents to the reinforced denture base resin.

Fungal biofilm formation and its regulatory mechanism

Fungal biofilm is a microbial community composed of fungal cells and extracellular polymeric substances (EPS). In recent years, fungal biofilms have played an increasingly important role in many fields. However, there are few studies on fungal biofilms and their related applications and development are still far from enough. Therefore, this review summarizes the composition and function of EPS in fungal biofilms, and improves and refines the formation process of fungal biofilms according to the latest viewpoints. Moreover, based on the study of Saccharomyces cerevisiae and Candida albicans, this review summarizes the gene regulation network of fungal biofilm synthesis, which is crucial for systematically understanding the molecular mechanism of fungal biofilm formation. It is of great significance to further develop effective methods at the molecular level to control harmful biofilms or enhance and regulate the formation of beneficial biofilms. Finally, the quorum sensing factors and mixed biofilms formed by fungi in the current research of fungal biofilms are summarized. These results will help to deepen the understanding of the formation process and internal regulation mechanism of fungal biofilm, provide reference for the study of EPS composition and structure, formation, regulation, group behavior and mixed biofilm formation of other fungal biofilms, and provide strategies and theoretical basis for the control, development and utilization of fungal biofilms.

An Injectable Living Hydrogel with Embedded Probiotics as a Novel Strategy for Combating Multifaceted Pathogen Wound Infections

Wound infections pose a significant challenge in healthcare, and traditional antibiotic treatments often result in the development of resistant pathogens. Addressing this gap, ProGel is introduced, a living hydrogel created by entrapping probiotic Lactobacillus plantarum as a therapeutic component within a gelatin matrix. With a double-syringe system, ProGel can be easily mixed and applied, conforming swiftly to any wound shape and forming hydrogel in situ. It also demonstrates robust mechanical and self-healing properties owing to the Schiff-base bonds. ProGel sustains more than 80% viability of the entrapped L. plantarum while restricting their escape from the hydrogel. After a week of storage, more than 70% viability of the entrapped L. plantarum is preserved. Importantly, ProGel exhibits broad-spectrum antimicrobial efficacy against pathogens commonly associated with wound infections, i.e., Pseudomonas aeruginosa (7Log reduction), Staphylococcus aureus (3-7Log reduction), and Candida albicans (40-70% reduction). Moreover, its cytocompatibility is affirmed through coculture with human dermal fibroblasts. The effectiveness of ProGel is further highlighted in more clinically relevant tests on human skin wound models infected with P. aeruginosa and S. aureus, where it successfully prevents the biofilm formation of these pathogens. This study showcases an injectable living hydrogel system for the management of complex wound infections.

Roles of alcohol dehydrogenase 1 in the biological activities of Candida albicans

Candida albicans stands as the foremost prevalent human commensal pathogen and a significant contributor to nosocomial fungal infections. In the metabolism of C. albicans, alcohol dehydrogenase 1 (Adh1) is one of the important enzymes that converts acetaldehyde produced by pyruvate decarboxylation into ethanol at the end of glycolysis. Leveraging the foundational processes of alcoholic fermentation, Adh1 plays an active role in multiple biological phenomena, including biofilm formation, interactions between different species, the development of drug resistance, and the potential initiation of gastrointestinal cancer. Additionally, Adh1 within C. albicans has demonstrated associations with regulating the cell cycle, stress responses, and various intracellular states. Furthermore, Adh1 is extracellularly localized on the cell wall surface, where it plays roles in processes such as tissue invasion and host immune responses. Drawing from an analysis of ADH1 gene structure, expression patterns, and fundamental functions, this review elucidates the intricate connections between Adh1 and various biological processes within C. albicans, underscoring its potential implications for the prevention, diagnosis, and treatment of candidiasis.

Structure-Based Optimization of Novel Sterol 24-C-Methyltransferase Inhibitors for the Treatment of Candida albicans Infections

Interfering with sterol biosynthesis is an important strategy for developing safe and effective antifungal drugs. We previously identified compound H55 as an allosteric inhibitor of the fungal-specific C-24 sterol methyltransferase Erg6 for treating Candida albicans infections. Herein, 62 derivatives of H55 were designed and synthesized based on target-ligand interactions to identify more active candidates. Among them, d28 displayed the most potent antivirulence ability (MHIC50 = 0.25 μg/mL) by targeting Erg6, exhibiting an 8-fold increase in potency compared with H55. Moreover, d28 significantly outperformed H55 in inhibiting cell adhesion and biofilm formation, and exhibited minimal cytotoxicity and negligible potential to induce drug resistance. Of note, the coadministration of d28 and other sterol biosynthesis inhibitors, such as tridemorph or terbinafine, demonstrated a strong synergistic antifungal action in vitro and in vivo in a murine skin infection model. These results support the potential application of d28 in the treatment of C. albicans infections.

Heterologous expression of the insect SVWC peptide WHIS1 inhibits Candida albicans invasion into A549 and HeLa epithelial cells

Candida albicans (C. albicans), a microbe commonly isolated from Candida vaginitis patients with vaginal tract infections, transforms from yeast to hyphae and produces many toxins, adhesins, and invasins, as well as C. albicans biofilms resistant to antifungal antibiotic treatment. Effective agents against this pathogen are urgently needed. Antimicrobial peptides (AMPs) have been used to cure inflammation and infectious diseases. In this study, we isolated whole housefly larvae insect SVWC peptide 1 (WHIS1), a novel insect single von Willebrand factor C-domain protein (SVWC) peptide from whole housefly larvae. The expression pattern of WHIS1 showed a response to the stimulation of C. albicans. In contrast to other SVWC members, which function as antiviral peptides, interferon (IFN) analogs or pathogen recognition receptors (PRRs), which are the prokaryotically expressed MdWHIS1 protein, inhibit the growth of C. albicans. Eukaryotic heterologous expression of WHIS1 inhibited C. albicans invasion into A549 and HeLa cells. The heterologous expression of WHIS1 clearly inhibited hyphal formation both extracellularly and intracellularly. Furthermore, the mechanism of WHIS1 has demonstrated that it downregulates all key hyphal formation factors (ALS1, ALS3, ALS5, ECE1, HWP1, HGC1, EFG1, and ZAP1) both extracellularly and intracellularly. These data showed that heterologously expressed WHIS1 inhibits C. albicans invasion into epithelial cells by affecting hyphal formation and adhesion factor-related gene expression. These findings provide new potential drug candidates for treating C. albicans infection.

Exploring the dynamics of mixed-species biofilms involving Candida spp. and bacteria in cystic fibrosis

Cystic fibrosis (CF) is an inherited disease that results from mutations in the gene responsible for the cystic fibrosis transmembrane conductance regulator (CFTR). The airways become clogged with thick, viscous mucus that traps microbes in respiratory tracts, facilitating colonization, inflammation and infection. CF is recognized as a biofilm-associated disease, it is commonly polymicrobial and can develop in biofilms. This review discusses Candida spp. and both Gram-positive and Gram-negative bacterial biofilms that affect the airways and cause pulmonary infections in the CF context, with a particular focus on mixed-species biofilms. In addition, the review explores the intricate interactions between fungal and bacterial species within these biofilms and elucidates the underlying molecular mechanisms that govern their dynamics. Moreover, the review addresses the multifaceted issue of antimicrobial resistance in the context of CF-associated biofilms. By synthesizing current knowledge and research findings, this review aims to provide insights into the pathogenesis of CF-related infections and identify potential therapeutic approaches to manage and combat these complex biofilm-mediated infections.

Structure-activity relationship and biofilm formation-related gene targets of oleanolic acid-type saponins from Pulsatilla chinensis against Candida albicans

In the course of our investigations of antifungal natural products, the structure-activity relationship and antifungal activities of oleanolic acid-type saponins (1-28) from Pulsatilla chinensis against human and plant pathogenic fungi were elucidated. The analysis of structure-activity relationship of oleanolic acid-type saponins showed that the free carboxyl at C-28 was essential for their antifungal activities; the free hydroxyl group at the C-23 site of oleanolic acid-type saponins played a crucial role in their antifungal activities; the oligosaccharide chain at C-3 oleanolic acid-type saponins showed significant effects on antifungal efficacy and a disaccharide or trisaccharide moiety at position C-3 displayed optimal antifungal activity. The typical saponin pulchinenoside B3 (16, PB3) displayed satisfactory antifungal activity against human and plant pathogenic fungi, especially, C. albicans with an MIC value of 12.5 μg/mL. Furthermore, PB3 could inhibit the biofilm formation of C. albicans through downregulating the expression of the integrated network of biofilm formation-associated transcription factors (Bcr1 Efg1, Ndt80, Brg1, Rob1 and Tec1) and adhesion-related target genes (HWP1, ALS1, and ALS3). Meanwhile, we found that PB3 could effectively destroy the mature biofilm of C. albicans by the oxidative damage and inducing mitochondria-mediated apoptosis in cells.

Antifungal drug resistance in Candida: a special emphasis on amphotericin B

Invasive fungal infections in humans caused by several Candida species, increased considerably in immunocompromised or critically ill patients, resulting in substantial morbidity and mortality. Candida albicans is the most prevalent species, although the frequency of these organisms varies greatly according to geographic region. Infections with C. albicans and non-albicans Candida species have become more common, especially in the past 20 years, as a result of aging, immunosuppressive medication use, endocrine disorders, malnourishment, extended use of medical equipment, and an increase in immunogenic diseases. Despite C. albicans being the species most frequently associated with human infections, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei also have been identified. Several antifungal drugs with different modes of action are approved for use in clinical settings to treat fungal infections. However, due to the common eukaryotic structure of humans and fungi, only a limited number of antifungal drugs are available for therapeutic use. Furthermore, drug resistance in Candida species has emerged as a result of the growing use of currently available antifungal drugs against fungal infections. Amphotericin B (AmB), a polyene class of antifungal drugs, is mainly used for the treatment of serious systemic fungal infections. AmB interacts with fungal plasma membrane ergosterol, triggering cellular ion leakage via pore formation, or extracting the ergosterol from the plasma membrane inducing cellular death. AmB resistance is primarily caused by changes in the content or structure of ergosterol. This review summarizes the antifungal drug resistance exhibited by Candida species, with a special focus on AmB.

Amphotericin B in the Era of New Antifungals: Where Will It Stand?

Amphotericin B (AmB) has long stood as a cornerstone in the treatment of invasive fungal infections (IFIs), especially among immunocompromised patients. However, the landscape of antifungal therapy is evolving. New antifungal agents, boasting novel mechanisms of action and better safety profiles, are entering the scene, presenting alternatives to AmB's traditional dominance. This shift, prompted by an increase in the incidence of IFIs, the growing demographic of immunocompromised individuals, and changing patterns of fungal resistance, underscores the continuous need for effective treatments. Despite these challenges, AmB's broad efficacy and low resistance rates maintain its essential status in antifungal therapy. Innovations in AmB formulations, such as lipid complexes and liposomal delivery systems, have significantly mitigated its notorious nephrotoxicity and infusion-related reactions, thereby enhancing its clinical utility. Moreover, AmB's efficacy in treating severe and rare fungal infections and its pivotal role as prophylaxis in high-risk settings highlight its value and ongoing relevance. This review examines AmB's standing amidst the ever-changing antifungal landscape, focusing on its enduring significance in current clinical practice and exploring its potential future therapeutic adaptations.

Synthesis of bio-stabilized silver nanoparticles using Roccella montagnei, their anticandidal capacities & potential to inhibit the virulence factors in fluconazole-resistant Candida albicans

Candida species is the causative agent in approximately 80% of invasive mycoses and drug-resistant Candida albicans is among the four strains of 'critical priority group' framed by WHO. Lichens are endowed with some rare phytochemicals and a plethora of therapeutics viz. antifungal capacities of Roccella montagnei. Biosynthesis of silver nanoparticles (AgNPs) using lichen could offer an eco-friendly, and cost-effective alternative against emerging 'microbial resistance.' Therefore, the objective was to biosynthesize silver nanoparticles (Rm-AgNPs) using a Hydro-alcoholic (1:1) extract of R. montagnei to develop a potent anticandidal agent against Fluconazole-resistant C. albicans NBC099. UV-Spectroscopy identified AgNPs specific-peak of Rm-AgNPs at 420-440 nm and FTIR revealed the presence of amines, alcohol, aromatic compounds, and acids. SEM and TEM analysis indicated that Rm-AgNPs are spherical shaped with a size range of 10-50 nm. Zetasizer analysis indicated that particles are highly stable and have a mean hydrodynamic diameter of 116 nm with a zeta potential charge of - 41 mV. XRD analysis suggested face centered cubic crystal lattice structure. Results indicated that Rm-AgNPs strongly inhibited the growth of NBC099 at a minimum inhibitory concentration (IC50) of ≤ 15 µg. C. albicans culture treated with Rm-AgNPs at concentrations below IC50, down-regulates the production of different virulence factors in NBC099, viz. hyphal formation (> 85%), biofilms production (> 80%), phospholipase, esterase, proteinase activity. The apoptosis assay demonstrated the Rm-AgNPs induced apoptosis in NBC099 cells via oxidative stress. Interestingly, Rm-AgNPs showed negligible cytotoxicity (< 6%) in murine RAW 246.7 macrophage cells at a concentration above 15 µg/mL. Therefore, Rm-AgNPs have been offered as an anti-candida alternative that can be utilized to improve the efficacy of already available medications.

Mechanophysical and Anti-Adhesive Properties of a Nanoclay-Containing PMMA Denture Resin

Poly(methyl methacrylate) (PMMA) is commonly used for dental dentures, but it has the drawback of promoting oral health risks due to oral bacterial adhesion. Recently, various nanoparticles have been incorporated into PMMA to tackle these issues. This study aims to investigate the mechanophysical and antimicrobial adhesive properties of a denture resin by incorporating of nanoclay into PMMA. Specimens were prepared by adding 0, 1, 2, and 4 wt % surface-modified nanoclay (Sigma) to self-polymerizing PMMA denture resin. These specimens were then evaluated using FTIR, TGA/DTG, and FE-SEM with EDS. Various mechanical and surface physical properties, including nanoindentation, were measured and compared with those of pure PMMA. Antiadhesion experiments were conducted by applying a Candida albicans (ATCC 11006) suspension to the surface of the specimens. The antiadhesion activity of C. albicans was confirmed through a yeast-wall component (mannan) and mRNA-seq analysis. The bulk mechanical properties of nanoclay-PMMA composites were decreased compared to those of pure PMMA, while the flexural strength and modulus met the ISO 20795-1 requirement. However, there were no significant differences in the nanoindentation hardness and elastic modulus. The surface energy revealed a significant decrease at 4 wt % nanoclay-PMMA. The antiadhesion effect of Candida albicans was evident along with nanoclay content in the nanocomposites and confirmed by the reduced attachment of mannan on nanoclay-PMMA composites. mRNA-seq analysis supported overall transcriptome changes in altering attachment and metabolism behaviors on the surface. The nanoclay-PMMA materials showed a lower surface energy as the content increased, leading to an antiadhesion effect against Candida albicans. These findings indicate that incorporating nanoclay into PMMA surfaces could be a valuable strategy for preventing the fungal biofilm formation of denture base materials.

The antimicrobial property of JY-1, a complex mixture of Traditional Chinese Medicine, is linked to it abilities to suppress biofilm formation and disrupt membrane permeability

The substantial increase of infections, caused by novel, sudden, and drug-resistant pathogens, poses a significant threat to human health. While numerous studies have demonstrated the antibacterial and antiviral effects of Traditional Chinese Medicine, the potential of a complex mixture of traditional Chinese Medicine with a broad-spectrum antimicrobial property remains underexplored. This study aimed to develop a complex mixture of Traditional Chinese Medicine (TCM), JY-1, and investigate its antimicrobial properties, along with its potential mechanism of action against pathogenic microorganisms. Antimicrobial activity was assessed using a zone of inhibition assay and the drop plate method. Hyphal induction of Candida albicans was conducted using RPMI1640 medium containing 10% FBS, followed by microscopic visualization. Quantitative real-time PCR (RT-qPCR) was employed to quantify the transcript levels of hyphal-specific genes such as HWP1 and ALS3. The impact of JY-1 on biofilm formation was evaluated using both the XTT reduction assay and scanning electron microscopy (SEM). Furthermore, the cell membrane integrity was assessed by protein and nucleic acid leakage assays. Our results clearly showed that JY-1 significantly inhibits the vegetative growth of Candida spp. and Cryptococcus spp. In addition, this complex mixture is effectively against a wide range of pathogenic bacteria, including Staphylococcus aureus, Vancomycin-resistant enterococci, Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae. More interestingly, JY-1 plays a direct anti-viral role against the mammalian viral pathogen vesicular stomatitis virus (VSV). Further mechanistic studies indicate that JY-1 acts to reduce the expression of hyphal specific genes HWP1 and ALS3, resulting in the suppression of the hyphal formation of C. albicans. The antimicrobial property of JY-1 could be attributed to its ability to reduce biofilm formation and disrupt the cell membrane permeability, a process resulting in microbial cell death and the release of cellular contents. Taken together, our work identified a potent broad-spectrum antimicrobial agent, a complex mixture of TCM which might be developed as a potential antimicrobial drug.

Artemisinin May Disrupt Hyphae Formation by Suppressing Biofilm-Related Genes of Candida albicans: In Vitro and In Silico Approaches

This study aimed to assess the antifungal and antibiofilm efficacy of artemisinin against Candida (C.) species, analyze its impact on gene expression levels within C. albicans biofilms, and investigate the molecular interactions through molecular docking. The antifungal efficacy of artemisinin on a variety of Candida species, including fluconazole-resistant and -susceptible species, was evaluated by the microdilution method. The effect of artemisinin on C. albicans biofilm formation was investigated by MTT and FESEM. The mRNA expression of the genes related to biofilm was analyzed by qRT-PCR. In addition, molecular docking analysis was used to understand the interaction between artemisinin and C. albicans at the molecular level with RAS1-cAMP-EFG1 and EFG1-regulated genes. Artemisinin showed higher sensitivity against non-albicans Candida strains. Furthermore, artemisinin was strongly inhibitory against C. albicans biofilms at 640 µg/mL. Artemisinin downregulated adhesion-related genes ALS3, HWP1, and ECE1, hyphal development genes UME6 and HGC1, and hyphal CAMP-dependent protein kinase regulators CYR1, RAS1, and EFG1. Furthermore, molecular docking analysis revealed that artemisinin and EFG1 had the highest affinity, followed by UME6. FESEM analysis showed that the fluconazole- and artemisinin-treated groups exhibited a reduced hyphal network, unusual surface bulges, and the formation of pores on the cell surfaces. Our study suggests that artemisinin may have antifungal potential and showed a remarkable antibiofilm activity by significantly suppressing adhesion and hyphal development through interaction with key proteins involved in biofilm formation, such as EFG1.

Pore-forming peptide C14R exhibits potent antifungal activity against clinical isolates of Candida albicans and Candida auris

Introduction

Invasive candidiasis is a global public health problem as it poses a significant threat in hospital-settings. The aim of this study was to evaluate C14R, an analog derived from peptide BP100, as a potential antimicrobial peptide against the prevalent opportunistic yeast Candida albicans and the emergent multidrug-resistant yeast Candida auris.

Methods

Antifungal susceptibility testing of C14R against 99 C. albicans and 105 C. auris clinical isolates from Colombia, was determined by broth microdilution. Fluconazole was used as a control antifungal. The synergy between C14R and fluconazole was assessed in resistant isolates. Assays against fungal biofilm and growth curves were also carried out. Morphological alterations of yeast cell surface were evaluated by scanning electron microscopy. A permeability assay verified the pore-forming ability of C14R.

Results

C. albicans and C. auris isolates had a geometric mean MIC against C14R of 4.42 µg/ml and 5.34 µg/ml, respectively. Notably, none of the isolates of any species exhibited growth at the highest evaluated peptide concentration (200 µg/ml). Synergistic effects were observed when combining the peptide and fluconazole. C14R affects biofilm and growth of C. albicans and C. auris. Cell membrane disruptions were observed in both species after treatment with the peptide. It was confirmed that C14R form pores in C. albicans' membrane.

Discussion

C14R has a potent antifungal activity against a large set of clinical isolates of both C. albicans and C. auris, showing its capacity to disrupt Candida membranes. This antifungal activity remains consistent across isolates regardless of their clinical source. Furthermore, the absence of correlation between MICs to C14R and resistance to fluconazole indicates the peptide's potential effectiveness against fluconazole-resistant strains. Our results suggest the potential of C14R, a pore-forming peptide, as a treatment option for fungal infections, such as invasive candidiasis, including fluconazole and amphotericin B -resistant strains.

Anti-Biofilm Activity of Assamsaponin A, Theasaponin E1, and Theasaponin E2 against Candida albicans

Biofilm formation plays a crucial role in the pathogenesis of Candida albicans and is significantly associated with resistance to antifungal agents. Tea seed saponins, a class of non-ionic triterpenes, have been proven to have fungicidal effects on planktonic C. albicans. However, their anti-biofilm activity and mechanism of action against C. albicans remain unclear. In this study, the effects of three Camellia sinensis seed saponin monomers, namely, theasaponin E1 (TE1), theasaponin E2 (TE2), and assamsaponin A (ASA), on the metabolism, biofilm development, and expression of the virulence genes of C. albicans were evaluated. The results of the XTT reduction assay and crystal violet (CV) staining assay demonstrated that tea seed saponin monomers concentration-dependently suppressed the adhesion and biofilm formation of C. albicans and were able to eradicate mature biofilms. The compounds were in the following order in terms of their inhibitory effects: ASA > TE1 > TE2. The mechanisms were associated with reductions in multiple crucial virulence factors, including cell surface hydrophobicity (CSH), adhesion ability, hyphal morphology conversion, and phospholipase activity. It was further demonstrated through qRT-PCR analysis that the anti-biofilm activity of ASA and TE1 against C. albicans was attributed to the inhibition of RAS1 activation, which consequently suppressed the cAMP-PKA and MAPK signaling pathways. Conversely, TE2 appeared to regulate the morphological turnover and hyphal growth of C. albicans via a pathway that was independent of RAS1. These findings suggest that tea seed saponin monomers are promising innovative agents against C. albicans.

Studying mixed-species biofilms of Candida albicans and Staphylococcus aureus using evolutionary game theory

Mixed-species biofilms of Candida albicans and Staphylococcus aureus pose a significant clinical challenge due to their resistance to the human immune system and antimicrobial therapy. Using evolutionary game theory and nonlinear dynamics, we analyse the complex interactions between these organisms to understand their coexistence in the human host. We determine the Nash equilibria and evolutionary stable strategies of the game between C. albicans and S. aureus and point out different states of the mixed-species biofilm. Using replicator equations we study the fungal-bacterial interactions on a population level. Our focus is on the influence of available nutrients and the quorum sensing molecule farnesol, including the potential therapeutic use of artificially added farnesol. We also investigate the impact of the suggested scavenging of C. albicans hyphae by S. aureus. Contrary to common assumptions, we confirm the hypothesis that under certain conditions, mixed-species biofilms are not universally beneficial. Instead, different Nash equilibria occur depending on encountered conditions (i.e. varying farnesol levels, either produced by C. albicans or artificially added), including antagonism. We further show that the suggested scavenging of C. albicans' hyphae by S. aureus does not influence the overall outcome of the game. Moreover, artificially added farnesol strongly affects the dynamics of the game, although its use as a medical adjuvant (add-on medication) may pose challenges.

Cotton Fibers with a Lactic Acid-Like Surface for Re-establishment of Protective Lactobacillus Microbiota by Selectively Inhibiting Vaginal Pathogens

Failure to reconstruct the Lactobacillus microbiota is the major reason for the recurrence of vaginal infection. However, most empiric therapies focus on the efficacy of pathogen elimination but do not sufficiently consider the viability of Lactobacillus. Herein, cotton fibers with a lactic acid-like surface (LC) are fabricated by NaIO4 oxidation and L-isoserine grafting. The lactic acid analog chain ends and imine structure of LC can penetrate cell walls to cause protein cleavage in Escherichia coli and Candida albicans and inhibit vaginal pathogens. Meanwhile, the viability of Lactobacillus acidophilus is unaffected by the LC treatment, thus revealing a selective way to suppress pathogens as well as provide a positive route to re-establish protective microbiota in the vaginal tract. Moreover, LC has excellent properties such as good biosafety, antiadhesion, water absorption, and weight retention. The strategy proposed here not only is practical, but also provides insights into the treatment of vaginal infections.

Engineering a self-healing grafted chitosan-sodium alginate based hydrogel with potential keratinocyte cell migration property and inhibitory effect against fluconazole resistance Candida albicans biofilm

Biofilms developed by microorganisms cause an extremely severe clinical problem that leads to drug failure. Bioactive polymeric hydrogels display potential for controlling the formation of microorganism-based biofilms, but their rapid biodegradability in these biofilm sites is still a major challenge. To overcome this, chitosan (CS), a natural functional biomaterial, has been used because of its effective penetrability in the cell wall of microorganisms; however, its fast biodegradability has restricted its further use. Hence, in this study, to improve the stability of CS and increase its penetration retention inside a biofilm, grafted CS was prepared and then crosslinked with sodium alginate (SA) to synthesize CS-poly(MA-co-AA)SA hydrogel via a free radical grafting method, therefore enhancing its antibiofilm efficiency against biofilms. The prepared hydrogel demonstrated excellent effectiveness against (≥90 % inhibition) biofilms of Candida albicans. Additionally, in vitro and in vivo safety assays established that the prepared hydrogel can be used in a biofilm microenvironment and might reduce drug resistance burden owing to its long-term antibiofilm effect and improved CS stability at the biofilm site. Furthermore, in vitro wound healing outcomes of hydrogel indicated its potential application for chronic wound treatment. This research opens a new advanced strategy for biofilm-associated infection treatment, including wound treatment.

Red/Orange Autofluorescence in Selected Candida Strains Exposed to 405 nm Laser Light

BACKGROUND

Candida albicans and similar species are significant pathogens in immunocompromised and hospitalized individuals, known for mucosal colonization and bloodstream/organ invasion. Many pathogenic fungi, including these species, exhibit autofluorescence (R/OF) under specific light conditions, a feature crucial for their detection.

AIM

We investigated the use of a 405 nm diode laser for the direct observation of red/orange autofluorescence of Candida spp., common in the oral cavity, exploring its potential in health screenings.

METHODS

This study utilized cultures of Candida spp. on Sabouraud dextrose agar with Qdot 655 and 685 for fluorescence benchmarking, illuminated using a 405 nm diode laser (continuous wave, power 250 mW, 0.0425 J/cm² fluence, 0.0014 W/cm² power density). Images were captured using a yellow-filter camera at set intervals (48 to 144 h). Visual and computational analyses evaluated the R/OF in terms of presence, intensity, coloration, and intra-colony variation.

RESULTS

Most Candida strains displayed red/orange autofluorescence at all observation times, characterized by varied coloration and intra-colony distribution. Initially, there was an increase in R/OF intensity, which then stabilized in the later stages of observation.

CONCLUSIONS

The majority of the Candida strains tested are capable of emitting R/OF under 405 nm laser light. This finding opens up new possibilities for integrating R/OF detection into routine dental screenings for Candida spp.

Cell-free supernatants of probiotic consortia impede hyphal formation and disperse biofilms of vulvovaginal candidiasis causing Candida in an ex-vivo model

Vulvovaginal candidiasis is the second most common vaginal infection caused by drug-resistant Candida species that affects about 70-75% of reproductive age group women across the globe. As current-day antifungal drugs are ineffective against the biofilms formed by the drug-resistant Candida strains, several natural compounds and antagonistic microbes are being explored as alternative antifungal agents. In the present study, we investigated the anti-biofilm activity of Cell-Free Supernatant (CFS) extracted from the commercially available probiotics VSL-3 against the biofilms of Candida species and also evaluated their efficacy in curbing the yeast-to-hyphal transition. Various methodologies like crystal violet staining and scanning electron microscopy were used to study the effect of CFS against the biofilms formed by the species. The ability of CFS to interfere with yeast to hyphal transition in Candida was studied by colony morphology assay and visually confirmed with phase contrast microscopy. The potential of the CFS of the probiotics was also evaluated using goat buccal tissue, a novel ex-vivo model that mimics the vaginal environment. Moreover, the supernatant extracted from VSL-3 had the ability to down-regulate the expression of virulence genes of Candida from the biofilm formed over the ex-vivo model. These results emphasize the anti-fungal and anti-infective properties of the CFS of VSL-3 against drug-resistant Candida strains causing vulvovaginal candidiasis.

Exploring the Therapeutic Potential of Scorpion-Derived Css54 Peptide Against Candida albicans

Candida albicans (C. albicans) is one of the most common opportunistic fungi worldwide, which is associated with a high mortality rate. Despite treatment, C. albicans remains the leading cause of life-threatening invasive infections. Consequently, antimicrobial peptides (AMPs) are potential alternatives as antifungal agents with excellent antifungal activity. We previously reported that Css54, found in the venom of Centrurodies suffusus suffusus (C. s. suffusus) showed antibacterial activity against zoonotic bacteria. However, the antifungal activity of Css54 has not yet been elucidated. The objective of this study was to identify the antifungal activity of Css54 against C. albicans and analyze its mechanism. Css54 showed high antifungal activity against C. albicans. Css54 also inhibited biofilm formation in fluconazole-resistant fungi. The antifungal mechanism of action of Css54 was investigated using membrane-related assays, including the membrane depolarization assay and analysis of the membrane integrity of C. albicans after treatment with Css54. Css54 induced reactive oxygen species (ROS) production in C. albicans, which affected its antifungal activity. Our results indicate that Css54 causes membrane damage in C. albicans, highlighting its value as a potential therapeutic agent against C. albicans infection.

Deciphering the antifungal mechanism and functional components of cinnamomum cassia essential oil against Candida albicans through integration of network-based metabolomics and pharmacology, the greedy algorithm, and molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Fungal pathogens can cause deadly invasive infections and have become a major global public health challenge. There is an urgent need to find new treatment options beyond established antifungal agents, as well as new drug targets that can be used to develop novel antifungal agents. Cinnamomum cassia is a tropical aromatic plant that has a wide range of applications in traditional Chinese medicine, especially in the treatment of bacterial and fungal infections.

AIM OF THE STUDY

The present study aimed to explore the mechanism of action and functional components of Cinnamomum cassia essential oil (CEO) against Candida albicans using an integrated strategy combining network-based metabolomics and pharmacology, the greedy algorithm and molecular docking.

MATERIALS AND METHODS

CEO was extracted using hydrodistillation and its chemical composition was identified by GC-MS. Cluster analysis was performed on the compositions of 19 other CEOs from the published literature, as well as the sample obtained in this study. The damages of C. albicans cells upon treatment with CEO was observed using a scanning electron microscope. The mechanisms of its antifungal effect at a subinhibitory concentration of 0.1 × MIC were determined using microbial metabolomics and network analysis. The functional components were studied using the greedy algorithm and molecular docking.

RESULTS

A total of 69 compounds were identified in the chemical analysis of CEO, which accounted for 90% of the sample. The major compounds were terpenoids (34.04%), aromatic compounds (4.52%), aliphatic compounds (0.9%), and others. Hierarchical cluster analysis of the compositions of 20 essential oils extracted from Cinnamomum cassia grown in different geographical locations showed a wide diversity of chemical composition with four major chemotypes. CEO showed strong antifungal activity and caused destruction of cell membranes in a concentration-dependent way. Metabolic fingerprint analysis identified 29 metabolites associated with lipid metabolism, which were mapped to 23 core targets mainly involved in fatty acid biosynthesis and metabolism. Six antifungal functional components of CEO were identified through network construction, greedy algorithm and molecular docking, including trans-cinnamaldehyde, δ-cadinol, ethylcinnamate, safrole, trans-anethole, and trans-cinnamyl acetate, which showed excellent binding with specific targets of AKR1B1, PPARG, BCHE, CYP19A1, CYP2C19, QPCT, and CYP51A1.

CONCLUSIONS

This study provides a systematic understanding of the antifungal activity of CEO and offers an integrated strategy for deciphering the potential metabolism and material foundation of complex component drugs.

Gold nanoparticle adsorption alters the cell stiffness and cell wall bio-chemical landscape of Candida albicans fungal cells

HYPOTHESIS

Nanomaterials have been extensively investigated for a wide range of biomedical applications, including as antimicrobial agents, drug delivery vehicles, and diagnostic devices. The commonality between these biomedical applications is the necessity for the nanoparticle to interact with or pass through the cellular wall and membrane. Cell-nanomaterial interactions/uptake can occur in various ways, including adhering to the cell wall, forming aggregates on the surface, becoming absorbed within the cell wall itself, or transversing into the cell cytoplasm. These interactions are common to mammalian cells, bacteria, and yeast cells. This variety of interactions can cause changes to the integrity of the cell wall and the cell overall, but the precise mechanisms underpinning such interactions remain poorly understood. Here, we investigate the interaction between commonly investigated gold nanoparticles (AuNPs) and the cell wall/membrane of a model fungal cell to explore the general effects of interaction and uptake.

EXPERIMENTS

The interactions between 100 nm citrate-capped AuNPs and the cell wall of Candida albicans fungal cells were studied using a range of advanced microscopy techniques, including atomic force microscopy, confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, and synchrotron-FTIR micro-spectroscopy.

FINDINGS

In most cases, particles adhered on the cell surface, although instances of particles being up-taken into the cell cytoplasm and localised within the cell wall and membrane were also observed. There was a measurable increase in the stiffness of the fungal cell after AuNPs were introduced. Analysis of the synchrotron-FTIR data showed significant changes in spectral features associated with phospholipids and proteins after exposure to AuNPs.

Supramolecular Self-Associating Amphiphiles Inhibit Biofilm Formation by the Critical Pathogens, Pseudomonas aeruginosa and Candida albicans

In 2019, 4.95 million deaths were directly attributed to antimicrobial-resistant bacterial infections globally. In addition, the mortality associated with fungal infections is estimated at 1.7 million annually, with many of these deaths attributed to species that are no longer susceptible to traditional therapeutic regimes. Herein, we demonstrate the use of a novel class of supramolecular self-associating amphiphilic (SSA) salts as antimicrobial agents against the critical pathogens Pseudomonas aeruginosa and Candida albicans. We also identify preliminary structure-activity relationships for this class of compound that will aid the development of next-generation SSAs demonstrating enhanced antibiofilm activity. To gain insight into the possible mode of action for these agents, a series of microscopy studies were performed, taking advantage of the intrinsic fluorescent nature of benzothiazole-substituted SSAs. Analysis of these data showed that the SSAs interact with the cell surface and that a benzothiazole-containing SSA inhibits hyphal formation by C. albicans.

Effectiveness of Chitosan versus Natural Aloe Vera on Candida Adherence in Denture Soft Lining Material

Background

Soft denture lining materials act as a cushion between the denture base and tissues. Alongside having many advantages, its main problem is candida growth due to its rubbery and porous texture. Many interventions have been performed to halt the growth of candida within soft lining materials such as the use of antifungal therapy and strict oral and denture hygiene but there are consequences such as recurrence, drug resistance, and toxicity related to these interventions. Since natural agents such as aloe vera and chitosan have been proven to have antibacterial and antifungal properties with minimum adverse effects, this study aimed to study the effectiveness of chitosan and aloe vera powders incorporated within denture soft lining materials against candida adherence. Methodology. A total of 60 soft-lining material samples were prepared that were equally divided into three groups, viz., group 1 (chitosan incorporation), group 2 (aloe vera incorporation), and group 3 (control). Candida was obtained from the microbiology lab to form a candidal suspension, diluted in 0.9% NaCl to match the McFarland standard bacteriologic solution. Samples were incubated at 37°C for 24 hours in test tubes containing 100 mL of the candidal suspension and 9.9 mL of the previously prepared Sabouraud dextrose agar. Crystal violet stain was used to stain the adhering cells by fixing them with methanol 80%. For each sample, the adhering candida cells were counted on three standard fields by using an inverted light microscope, and the mean of those fields was recorded.

Results

The mean value for samples containing aloe vera was 41.15, while the mean values for samples containing chitosan and the control group were 16.05 and 79.1, respectively. Of all the three groups, aloe vera powder had a significant efficacy against candida growth as compared to the chitosan and control groups (P value = 0.001).

Conclusion

Both herbal agents were effective against candida growth. In comparison, aloe vera was more effective against candida growth compared to chitosan.

Exploring therapeutic avenues: mesenchymal stem/stromal cells and exosomes in confronting enigmatic biofilm-producing fungi

Fungal infections concomitant with biofilms can demonstrate an elevated capacity to withstand substantially higher concentrations of antifungal agents, contrasted with infectious diseases caused by planktonic cells. This inherent resilience intrinsic to biofilm-associated infections engenders a formidable impediment to effective therapeutic interventions. The different mechanisms that are associated with the intrinsic resistance of Candida species encompass drug sequestration by the matrix, drug efflux pumps, stress response cell density, and the presence of persister cells. These persisters, a subset of fungi capable of surviving hostile conditions, pose a remarkable challenge in clinical settings in virtue of their resistance to conventional antifungal therapies. Hence, an exigent imperative has arisen for the development of novel antifungal therapeutics with specific targeting capabilities focused on these pathogenic persisters. On a global scale, fungal persistence and their resistance within biofilms generate an urgent clinical need for investigating recently introduced therapeutic strategies. This review delves into the unique characteristics of Mesenchymal stem/stromal cells (MSCs) and their secreted exosomes, which notably exhibit immunomodulatory and regenerative properties. By comprehensively assessing the current literature and ongoing research in this field, this review sheds light on the plausible mechanisms by which MSCs and their exosomes can be harnessed to selectively target fungal persisters. Additionally, prospective approaches in the use of cell-based therapeutic modalities are examined, emphasizing the importance of further research to overcome the enigmatic fungal persistence.

Antifungal therapy of Candida biofilms: Past, present and future

Virtually all Candida species linked to clinical candidiasis are capable of forming highly resistant biofilms on different types of surfaces, which poses an additional significant threat and further complicates therapy of these infections. There is a scarcity of antifungal agents, and their effectiveness, particularly against biofilms, is limited. Here we provide a historical perspective on antifungal agents and therapy of Candida biofilms. As we reflect upon the past, consider the present, and look towards the future of antifungal therapy of Candida biofilms, we believe that there are reasons to remain optimistic, and that the major challenges of Candida biofilm therapy can be conquered within a reasonable timeframe.

Anti-Biofilm Activity of Cocultimycin A against Candida albicans

Candida albicans (C. albicans), the most common fungal pathogen, has the ability to form a biofilm, leading to enhanced virulence and antibiotic resistance. Cocultimycin A, a novel antifungal antibiotic isolated from the co-culture of two marine fungi, exhibited a potent inhibitory effect on planktonic C. albicans cells. This study aimed to evaluate the anti-biofilm activity of cocultimycin A against C. albicans and explore its underlying mechanism. Crystal violet staining showed that cocultimycin A remarkably inhibited biofilm formation in a dose-dependent manner and disrupted mature biofilms at higher concentrations. However, the metabolic activity of mature biofilms treated with lower concentrations of cocultimycin A significantly decreased when using the XTT reduction method. Cocultimycin A could inhibit yeast-to-hypha transition and mycelium formation of C. albicans colonies, which was observed through the use of a light microscope. Scanning electron microscopy revealed that biofilms treated with cocultimycin A were disrupted, yeast cells increased, and hypha cells decreased and significantly shortened. The adhesive ability of C. albicans cells treated with cocultimycin A to the medium and HOEC cells significantly decreased. Through the use of a qRT-PCR assay, the expression of multiple genes related to adhesion, hyphal formation and cell membrane changes in relation to biofilm cells treated with cocultimycin A. All these results suggested that cocultimycin A may be considered a potential novel molecule for treating and preventing biofilm-related C. albicans infections.

A Membrane-Targeted Photosensitizer Prevents Drug Resistance and Induces Immune Response in Treating Candidiasis

Candida albicans (C. albicans), a ubiquitous polymorphic fungus in humans, causes different types of candidiasis, including oral candidiasis (OC) and vulvovaginal candidiasis (VVC), which are physically and mentally concerning and financially costly. Thus, developing alternative antifungals that prevent drug resistance and induce immunity to eliminate Candida biofilms is crucial. Herein, a novel membrane-targeted aggregation-induced emission (AIE) photosensitizer (PS), TBTCP-QY, is developed for highly efficient photodynamic therapy (PDT) of candidiasis. TBTCP-QY has a high molar absorption coefficient and an excellent ability to generate 1 O2 and •OH, entering the interior of biofilms due to its high permeability. Furthermore, TBTCP-QY can efficiently inhibit biofilm formation by suppressing the expression of genes related to the adhesion (ALS3, EAP1, and HWP1), invasion (SAP1 and SAP2), and drug resistance (MDR1) of C. albicans, which is also advantageous for eliminating potential fungal resistance to treat clinical infectious diseases. TBTCP-QY-mediated PDT efficiently targets OC and VVC in vivo in a mouse model, induces immune response, relieves inflammation, and accelerates the healing of mucosal defects to combat infections caused by clinically isolated fluconazole-resistant strains. Moreover, TBTCP-QY demonstrates excellent biocompatibility, suggesting its potential applications in the clinical treatment of OC and VVC.

Photodynamic therapy in the treatment of denture stomatitis: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Photodynamic therapy is widely used in dentistry, but limited evidence exists regarding its effectiveness in treating denture stomatitis. High resistance to antifungals has been reported, and photodynamic therapy could be an alternative treatment.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate whether photodynamic therapy is effective in reducing denture stomatitis.

MATERIAL AND METHODS

A systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and recorded in the prospective register of systematic reviews (PROSPERO) (CRD42020205589) to answer the population, intervention, control, outcome (PICO) question: "Is photodynamic therapy effective in the treatment of denture stomatitis when compared with the use of antifungal agents?" Electronic searches were performed in databases PubMed/MEDLINE, Cochrane library, and Web of Science for articles published until February 2021 by using the following terms: (denture stomatitis OR oral candidiasis) AND (low-level light therapy OR laser therapy OR lasers OR photodynamic therapies OR photochemotherapy) AND (antifungal drugs OR antifungal agents OR antimicrobial OR treatment). Clinical trials and randomized clinical trials, studies in the English language, and studies comparing antifungal agents with photodynamic therapy were included.

RESULTS

In total, 5 articles were selected for the qualitative analysis and 3 for the meta-analysis. No significant difference was detected between antifungal therapy and photodynamic therapy in the reduction of colony-forming units on the palate. In a subgroup analysis, a significant difference was found in the reduction of colony-forming units on the palate at 15 days and at the denture surface at 30 days.

CONCLUSIONS

Photodynamic therapy is effective in the treatment of denture stomatitis, but after 30 days and 15 days, the antifungals demonstrated better performance.

Limosilactobacillus reuteri 29A Cell-Free Supernatant Antibiofilm and Antagonistic Effects in Murine Model of Vulvovaginal Candidiasis

Vaginal dysbiosis advocates burgeoning of devious human vaginal pathobionts like Candida species that possess multiple virulence properties and metabolic flexibility to cause infections. Inevitably, antifungal resistance may emerge due to their innate nature (e.g., biofilm formation), which assists in their virulence as well as the formation of persister cells after dispersal. In consequence, the phenomenon of biofilm involvement in vulvovaginal candidiasis (VVC) and its recurrence is becoming paramount. Lactic acid bacteria and their derivatives have proven to be hostile to Candida species. Here, we throw more light on the potency of the derivatives, i.e., cell-free supernatant (CFS) produced by an indigenously isolated vaginal Lactobacillus strain, Limosilactobacillus reuteri 29A. In the present study, we investigated the antibiofilm and antagonistic effects of L. reuteri 29A CFS, against biofilms of Candida species and in murine model of vulvovaginal candidiasis. In our in vitro biofilm study, the CFS disrupted and inhibited preformed biofilms of C. albicans and C. glabrata. Scanning electron microscopy displayed the destruction of preformed biofilms and impediment of C. albicans morphogenesis by the CFS. Gas chromatography-mass spectrometry analysis showed multiple key compounds that may act singly or synergistically. In vivo, the CFS showed no collateral damage to uninfected mice; the integrity of infected vaginal tissues was restored by the administration of the CFS as seen from the cytological, histopathological, and electron microscopical analyses. The results of this study document the potential use of CFS as an adjuvant or prophylactic option in addressing vaginal fungal infections.

The Early Endocytosis Gene PAL1 Contributes to Stress Tolerance and Hyphal Formation in Candida albicans

The endocytic and secretory pathways of the fungal pathogen Candida albicans are fundamental to various key cellular processes such as cell growth, cell wall integrity, protein secretion, hyphal formation, and pathogenesis. Our previous studies focused on several candidate genes involved in early endocytosis, including ENT2 and END3, that play crucial roles in such processes. However, much remains to be discovered about other endocytosis-related genes and their contributions toward Candida albicans secretion and virulence. In this study, we examined the functions of the early endocytosis gene PAL1 using a reverse genetics approach based on CRISPR-Cas9-mediated gene deletion. Saccharomyces cerevisiae Pal1 is a protein in the early coat complex involved in clathrin-mediated endocytosis that is later internalized with the coat. The C. albicans pal1Δ/Δ null mutant demonstrated increased resistance to the antifungal agent caspofungin and the cell wall stressor Congo Red. In contrast, the null mutant was more sensitive to the antifungal drug fluconazole and low concentrations of SDS than the wild type (WT) and the re-integrant (KI). While pal1Δ/Δ can form hyphae and a biofilm, under some hyphal-inducing conditions, it was less able to demonstrate filamentous growth when compared to the WT and KI. The pal1Δ/Δ null mutant had no defect in clathrin-mediated endocytosis, and there were no changes in virulence-related processes compared to controls. Our results suggest that PAL1 has a role in susceptibility to antifungal agents, cell wall integrity, and membrane stability related to early endocytosis.

Biofilm tolerance, resistance and infections increasing threat of public health

Microbial biofilms can cause chronic infection. In the clinical setting, the biofilm-related infections usually persist and reoccur; the main reason is the increased antibiotic resistance of biofilms. Traditional antibiotic therapy is not effective and might increase the threat of antibiotic resistance to public health. Therefore, it is urgent to study the tolerance and resistance mechanism of biofilms to antibiotics and find effective therapies for biofilm-related infections. The tolerance mechanism and host reaction of biofilm to antibiotics are reviewed, and bacterial biofilm related diseases formed by human pathogens are discussed thoroughly. The review also explored the role of biofilms in the development of bacterial resistance mechanisms and proposed therapeutic intervention strategies for biofilm related diseases.

Candida albicans Biofilm-Derived Extracellular Vesicles Are Involved in the Tolerance to Caspofungin, Biofilm Detachment, and Fungal Proteolytic Activity

It has been repeatedly reported that the cells of organisms in all kingdoms of life produce nanometer-sized lipid membrane-enveloped extracellular vesicles (EVs), transporting and protecting various substances of cellular origin. While the composition of EVs produced by human pathogenic fungi has been studied in recent decades, another important challenge is the analysis of their functionality. Thus far, fungal EVs have been shown to play significant roles in intercellular communication, biofilm production, and modulation of host immune cell responses. In this study, we verified the involvement of biofilm-derived EVs produced by two different strains of Candida albicans-C. albicans SC5314 and 3147 (ATCC 10231)-in various aspects of biofilm function by examining its thickness, stability, metabolic activity, and cell viability in the presence of EVs and the antifungal drug caspofungin. Furthermore, the proteolytic activity against the kininogen-derived antimicrobial peptide NAT26 was confirmed by HPLC analysis for C. albicans EVs that are known to carry, among others, particular members of the secreted aspartic proteinases (Saps) family. In conclusion, EVs derived from C. albicans biofilms were shown to be involved in biofilm tolerance to caspofungin, biofilm detachment, and fungal proteolytic activity.

Our current clinical understanding of Candida biofilms: where are we two decades on?

Clinically we have been aware of the concept of Candida biofilms for many decades, though perhaps without the formal designation. Just over 20 years ago the subject emerged on the back of progress made from the bacterial biofilms, and academic progress pace has continued to mirror the bacterial biofilm community, albeit at a decreased volume. It is apparent that Candida species have a considerable capacity to colonize surfaces and interfaces and form tenacious biofilm structures, either alone or in mixed species communities. From the oral cavity, to the respiratory and genitourinary tracts, wounds, or in and around a plethora of biomedical devices, the scope of these infections is vast. These are highly tolerant to antifungal therapies that has a measurable impact on clinical management. This review aims to provide a comprehensive overight of our current clinical understanding of where these biofilms cause infections, and we discuss existing and emerging antifungal therapies and strategies.

Synergistic Effect of Plant Compounds in Combination with Conventional Antimicrobials against Biofilm of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida spp

Bacterial and fungal biofilm has increased antibiotic resistance and plays an essential role in many persistent diseases. Biofilm-associated chronic infections are difficult to treat and reduce the efficacy of medical devices. This global problem has prompted extensive research to find alternative strategies to fight microbial chronic infections. Plant bioactive metabolites with antibiofilm activity are known to be potential resources to alleviate this problem. The phytochemical screening of some medicinal plants showed different active groups, such as stilbenes, tannins, alkaloids, terpenes, polyphenolics, flavonoids, lignans, quinones, and coumarins. Synergistic effects can be observed in the interaction between plant compounds and conventional drugs. This review analyses and summarises the current knowledge on the synergistic effects of plant metabolites in combination with conventional antimicrobials against biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The synergism of conventional antimicrobials with plant compounds can modify and inhibit the mechanisms of acquired resistance, reduce undesirable effects, and obtain an appropriate therapeutic effect at lower doses. A deeper knowledge of these combinations and of their possible antibiofilm targets is needed to develop next-generation novel antimicrobials and/or improve current antimicrobials to fight drug-resistant infections attributed to biofilm.

The Pathogenic Yeast Metschnikowia bicuspidata var. bicuspidata in the Aquacultured Ecosystem and Its Biocontrol

M. bicuspidata var. bicuspidata is a pathogenic yeast which can affect aquacultured and marine-cultured animals such as brine shrimp, ridgetail white prawn, chinook salmon, giant freshwater prawn, the Chinese mitten crab, marine crab, the mud crab, the mangrove land crab, the Chinese grass shrimp, sea urchins, sea urchins, Daphnia dentifera and even snails, causing a milky disease, and it has caused big economic losses in aquacultural and marine-cultural industries in the past. However, the detailed mechanisms and the reasons for the milky disease in the diseased aquatic animals are still completely unknown. So far, only some antimycotics, killer toxins and Massoia lactone haven been found to be able to actively control and kill its growth. The ecofriendly, green and renewable killer toxins and Massoia lactone have high potential for application in controlling the milky disease.