Development and regulation of single- and multi-species Candida albicans biofilms

Eicosapentaenoic acid as an antibiofilm agent disrupts mature biofilms of Candida albicans

The biofilm formation of Candida albicans, a major human fungal pathogen, represents a crucial virulence factor during candidiasis. Eicosapentaenoic acid (EPA), a polyunsaturated fatty acid, has emerged as a potential antibiofilm agent against C. albicans. Herein, we aim to investigate the antifungal effect of EPA (1 mM) on the mature biofilm of C. albicans and explore the underlying mechanism. Crystal violet and XTT assays showed that EPA exerted a strong inhibitory efficacy on preformed biofilms in C. albicans. Biofilm architecture and cell viability were observed using scanning electron microscopy and confocal laser scanning microscopy, indicating that EPA could block the yeast-to-hypha transition and damage the structure, thereby exhibiting antibiofilm activity. RNA sequencing analysis revealed that EPA treatment led to the downregulation of genes associated with hyphal formation and biofilm development. From the signaling pathway perspective, EPA regulated the C. albicans biofilms involving two signaling pathways, namely, Ras1-cAMP-PKA and Cek-MAPK pathways. Additionally, the EPA could effectively reduce the production of key messenger cAMP in the Ras1-cAMP-PKA pathway. Interestingly, in response to EPA, ergosterol biosynthesis-related genes were down-regulated, indicating EPA as antifungal agent might reduce the risk of developing drug resistance. The findings of this study highlight the potential of EPA as an alternative or adjunctive antibiofilm agent against C. albicans-related infections.

Fungal biofilms in human health and disease

Increased use of implanted medical devices, use of immunosuppressants and an ageing population have driven the rising frequency of fungal biofilm-related diseases. Fungi are now recognized by the World Health Organization (WHO) as an emergent threat to human health, with most medically important species defined as critical or high-priority organisms capable of forming biofilms. Although we strive for a better understanding of diagnostic and therapeutic approaches to detect and treat these fungal diseases more generally, the issue of hard-to-treat biofilms is an ever-increasing problem. These are communities of interspersed cells that are attached to one another on a surface, such as a catheter, or trapped into a cavity such as a paranasal sinus. Biofilms are difficult to detect, difficult to remove and intrinsically tolerant to most antifungal agents. These factors can lead to devastating consequences for the patient, including unnecessary morbidity and mortality, need for reoperations and prolonged hospital stay. This Review describes the breadth and growing impact fungal biofilms have on patient management and explains the mechanisms promoting biofilm formation, focusing on how targeting these can improve therapeutic options.

Chemical composition of the traditional Chinese medicine compound (ICAM), its antifungal effects against Candida albicans, and the underlying Mechanisms: Therapeutic potential and safety evaluation for vulvovaginal candidiasis

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) compound preparations play a significant role in the clinical treatment of vulvovaginal candidiasis (VVC).

AIM OF THE STUDY

Candida albicans (CA) is an opportunistic fungal pathogen responsible for various human diseases, including vulvovaginal candidiasis (VVC). Hyphal growth and biofilm formation are critical virulence factors contributing to CA's pathogenicity and drug resistance. ICAM, a topical TCM compound preparation developed by our laboratory, was investigated for its chemical component, antifungal mechanisms against CA and therapeutic efficacy against VVC.

MATERIALS AND METHODS

The main components of ICAM were analyzed using the Gas Chromatography-Mass Spectrometry (GC-MS) method. To elucidate the mechanisms underlying ICAM's antifungal activity, we combined phenotypic assays, transcriptomic and proteomic analyses. The therapeutic potential of ICAM for VVC and its irritancy to vaginal tissue were evaluated using cavity model experiments.

RESULTS

ICAM contained a diverse range of phenolic compounds, such as phenol, 2-methoxyphenol, and 4-ethyl-2-methoxyphenol, among others. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of ICAM against CA were 2.50 % and 10.00 % for the standard strain, and 5.00 % and 20.00 % for the clinical strain, respectively. At 1.25 %, ICAM significantly inhibited CA adherence, hyphal growth, and biofilm formation, while also reducing surface hydrophobicity and exopolysaccharide production. Treatment with 10.00 % ICAM completely disrupted CA membrane integrity. Transcriptome analysis revealed that multiple genes associated with biofilm and hyphal formation, including five MAPK signaling pathway genes (Ras1, Cdc24, Ste11, Cek1, Hst7), four hyphae-specific genes (Hgc1, Hwp1, Ece1, Als3), and three additional genes (Tec1, Csh1, Pmt1), were significantly downregulated. Additionally, proteins associated with the MAPK signaling pathway, including the 14-3-3 domain-containing protein, cell wall protein RTB1, Msb2p, Ras family protein, and RhoGAP domain family protein, were significantly downregulated. These findings suggest that the MAPK signaling pathway plays a crucial role in mediating ICAM's inhibition of hyphal growth and biofilm formation in CA. In vivo, 10.00 % ICAM completely eliminated the symptoms of CA infection. The vaginal fungal burden in the 20.00 % and 40.00 % ICAM groups was reduced to zero after 12 days of treatment. Furthermore, 40.00 % ICAM significantly reduced lactate dehydrogenase and inflammatory cytokine levels, demonstrating efficacy comparable to the positive control. ICAM demonstrated excellent mucosal compatibility in the cavity experiment.

CONCLUSIONS

These findings highlight the potential of ICAM as a novel antifungal agent for the treatment of VVC.

Antibiofilm activity of manogepix, ibrexafungerp, amphotericin B, rezafungin, and caspofungin against Candida spp. biofilms of reference and clinical strains

This study comprehensively assessed the activity of manogepix (MNGX), ibrexafungerp (IBF), amphotericin B (AMB), rezafungin (RZF), and caspofungin (CAS) against planktonic cells and mature biofilms of Candida spp.-reference and clinical strains using the Calgary biofilm device. Mature-phase biofilms of C. albicans, C. auris (clades I, II, III, IV), and C. parapsilosis were exposed to a range of drug concentrations (0.12-128 µg/mL). Minimum Inhibitory Concentration (MIC) values for planktonic cells were ≤2 µg/mL for all strains; however, biofilm-associated MICs, minimum biocidal concentration (MBC), minimum biofilm eradication (MBEC), and minimum biofilm damaging concentration (MBDC) were significantly higher (2-4,119 times). Geometric mean (GM) of MBEC values indicated that MNGX had the highest antifungal activity within Candida species, with a GM-MBEC of 5.9 µg/mL. Despite its overall potency, MNGX was less effective against C. auris biofilms from clade IV strains, where IBF showed superior activity. While not the most potent agent overall, AMB induced the smallest fold-change increases (2- to 32-fold) in biofilm-associated states data compared to planktonic MICs. Conversely, CAS exhibited the lowest activity against Candida spp. biofilms. The eradication of C. auris and C. parapsilosis biofilms required substantially higher concentrations than C. albicans, with some agents, such as RZF and CAS, necessitating up to 42-fold increases in dosage. In conclusion, our in vitro model highlights the antibiofilm activity of novel antifungals against major Candida species, revealing significant differences in efficacy among species. MNGX demonstrated the highest activity, underscoring its potential as a promising candidate for the treatment of biofilm-related infections.

Characterization of virulence-related phenotypes of Candida parapsilosis and Rhodotorula mucilaginosa isolated from the International Space Station (ISS)

There is increased interest in characterizing and describing the effects of space stressors on human microflora. This study describes virulence-related phenotypes of two human yeast commensals, Rhodotorula mucilaginosa and Candida parapsilosis, isolated from the International Space Station (ISS). The strains were compared with ATCC control strains to provide insights into adaptation and phenotypic switching of fungal species in spacecraft environments. Strains were grown in media that induce filamentation and capsule production. Antimycotic susceptibility was determined after exposure of liquid cultures to fluconazole, amphotericin B, and caspofungin. Biofilm formation was quantified using the crystal violet assay, and autoinducer (AI) production was detected by activation of a reporter fluorescent gene present in biosensor bacterial strains. In vivo infection studies were conducted using a C. elegans killing model. Results indicated increased filamentation production patterns in ISS Candida parapsilosis and increased capsule production in ISS Rhodotorula. Additionally, there was increased resistance to antifungal activity, biofilm formation, long-chain autoinducer production, and heightened nematode virulence detected in the ISS isolates. These results suggest that space conditions might enhance adaptation and phenotypic plasticity in yeast, leading to increased virulence-related phenotypes.

Vaginal mycobiome characteristics and therapeutic strategies in vulvovaginal candidiasis (VVC): differentiating pathogenic species and microecological features for stratified treatment

SUMMARYVulvovaginal candidiasis (VVC) is a prevalent global health burden, particularly among reproductive-aged women. Recurrent VVC affects a significant proportion of this population, presenting therapeutic challenges. The predominant pathogen, Candida albicans, opportunistically transitions from a commensal organism to a pathogen when microenvironmental conditions become dysregulated. Recently, non-albicans Candida species have gained attention for their reduced antifungal susceptibility and recurrence tendencies. Diagnosis is constrained by the limitations of conventional microbiological techniques, while emerging molecular assays offer enhanced pathogen detection yet lack established thresholds to differentiate between commensal and pathogenic states. Increasing resistance issues are encountered by traditional azole-based antifungals, necessitating innovative approaches that integrate microbiota modulation and precision medicine. Therefore, this review aims to systematically explore the pathogenic diversity, drug resistance mechanisms, and biofilm effects of Candida species. Vaginal microbiota (VMB) alterations associated with VVC were also examined, focusing on the interaction between Lactobacillus spp. and pathogenic fungi, emphasizing the role of microbial dysbiosis in disease progression. Finally, the potential therapeutic approaches for VVC were summarized, with a particular focus on the use of probiotics to modulate the VMB composition and restore a healthy microbial ecosystem as a promising treatment strategy. This review addresses antifungal resistance and adopts a microbiota-centric approach, proposing a comprehensive framework for personalized VVC management to reduce recurrence and improve patient outcomes.

Artificial Bone Materials for Infected Bone Defects: Advances in Antimicrobial Functions

Infected bone defects, caused by bacterial contamination following disease or injury, result in the partial loss or destruction of bone tissue. Traditional bone transplantation and other clinical approaches often fail to address the therapeutic complexities of these conditions effectively. In recent years, advanced biomaterials have attracted significant attention for their potential to enhance treatment outcomes. This review explores the pathogenic mechanisms underlying infected bone defects, including biofilm formation and bacterial internalization into bone cells, which allow bacteria to evade the host immune system. To control bacterial infection and facilitate bone repair, we focus on antibacterial materials for bone regeneration. A detailed introduction is given on intrinsically antibacterial materials (e.g., metal alloys, oxide materials, carbon-based materials, hydroxyapatite, chitosan, and Sericin). The antibacterial functionality of bone repair materials can be enhanced through strategies such as the incorporation of antimicrobial ions, surface modification, and the combined use of multiple materials to treat infected bone defects. Key innovations discussed include biomaterials that release therapeutic agents, functional contact biomaterials, and bioresponsive materials, which collectively enhance antibacterial efficacy. Research on the clinical translation of antimicrobial bone materials has also facilitated their practical application in infection prevention and bone healing. In conclusion, advancements in biomaterials provide promising pathways for developing more biocompatible, effective, and personalized therapies to reconstruct infected bone defects.

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.

Nano Copper-chelate Triggers Cuproptosis-like Death in Fungi and Synergizes with Microneedles for Enhanced Biofilm Removal

Fungal infections pose a significant global public health threat, particularly candidemia and biofilm formation. Current antifungal drugs have limitations due to their toxicity and drug resistance. Ion interference therapy, particularly cuproptosis, shows significant potential for disease treatment. Herein, nano copper-chelate Cu(DDC)2@BSA (CDB) is synthesized for antifungal research and the mechanism of cuproptosis-like death is investigated. Initially, CDB demonstrates a strong inhibitory effect on multiple fungi and exhibits strong antifungal activity against two fluconazole-resistant clinical isolates. The decrease in ATPase activity and mitochondrial membrane potential indicates that the antifungal mechanism may involve mitochondrial dysfunction. Subsequently, transcriptome analysis reveals significant alterations in genes related to copper ions transport and regulation, oxidative phosphorylation, and mitochondrial function. Additionally, copper ions overload is observed, along with an increase in heat shock protein 70 levels and a decrease in lipoic acid synthetase protein expression. Given that biofilms hinder drug penetration, quaternary ammonium chitosan microneedles are employed in combination with CDB to penetrate the biofilm barrier and enhance the antifungal effect. Overall, this study provides new insight into the cuproptosis-like death mechanism in fungi and presents a promising strategy for fungal infection treatment through the combination of nano copper-chelate and microneedle delivery system.

ML-AMPs designed through machine learning show antifungal activity against C. albicans and therapeutic potential on mice model with candidiasis

AIMS

C. albicans resistant strains have led to increasingly severe treatment challenges. Antimicrobial peptides with low resistance-inducing propensity for pathogens have been developed. A series of antimicrobial peptides de novo designed through machine learning by our research team were named ML-AMPs. In the present research, the antifungal activity of ML-AMPs against C. albicans and its therapeutic potential on Candidiasis mice model were studied.

MAIN METHODS

MTT methodology was performed to measure the minimum inhibitory concentrations. Absorbance photometry was utilized to evaluate the erythrocyte toxicity. Optical microscopy was operated to observe C. albicans hyphae. Crystal violet staining was employed to assess biofilm inhibition and reduction. Colony counting was performed to determine the time-kill kinetics. Scanning electron microscopy and fluorescent staining were used to investigate the underlying mechanism of antifungal action. Candidiasis mice model was established to evaluate the in vivo efficacy of ML-AMP2.

KEY FINDINGS

ML-AMPs exhibited strong anti-Candida activity, with minimum inhibitory concentrations against C. albicans ranging from 3.85 to 12.37 μg/mL. Notably, they exhibited robust fungicidal effects on fluconazole-resistant C. albicans. Moreover, they exhibited fast-killing kinetics, as well as low resistance potential. Additionally, ML-AMPs could effectively inhibit the formation of mycelium and biofilm, and more prominently, their ability to reduce biofilm was higher than that of fluconazole. ML-AMPS increased the permeability of C. albicans cell membrane and induced ROS accumulation. Among ML-AMPs, ML-AMP2 performed the best, which promoted the recovery of Candidiasis mice model.

SIGNIFICANCE

ML-AMP2 holds great promise as a candidate molecule for effectively treating drug-resistant C. albicans infections.

Biofilm-Associated Candidiasis: Pathogenesis, Prevalence, Challenges and Therapeutic Options

The rising prevalence of fungal infections, especially those caused by Candida species, presents a major risk to global health. With approximately 1.5 million deaths annually, the urgency for effective treatment options has never been greater. Candida spp. are the leading cause of invasive infections, significantly impacting immunocompromised patients and those in healthcare settings. C. albicans, C. parapsilosis and the emerging species C. auris are categorized as highly dangerous species because of their pathogenic potential and increasing drug resistance. This review comparatively describes the formation of microbial biofilms of both bacterial and fungal origin, including major pathogens, thereby creating a novel focus. Biofilms can further complicate treatment, as these structures provide enhanced resistance to antifungal therapies. Traditional antifungal agents, including polyenes, azoles and echinocandins, have shown effectiveness, yet resistance development continues to rise, necessitating the exploration of novel therapeutic approaches. Antimicrobial peptides (AMPs) such as the anti-biofilm peptides Pom-1 and Cm-p5 originally isolated from snails represent promising candidates due to their unique mechanisms of action and neglectable cytotoxicity. This review article discusses the challenges posed by Candida infections, the characteristics of important species, the role of biofilms in virulence and the potential of new therapeutic options like AMPs.

V-ATPase contributes to the cariogenicity of Candida albicans- Streptococcus mutans biofilm

The interaction between Candida albicans and Streptococcus mutans plays an important role in the progression of dental caries. The vacuolar proton pump (V-ATPase) is a vital enzyme regulating the growth and virulence of C. albicans, which is a potential target for caries prevention. However, the effect of V-ATPase on the cariogenicity of C. albicans-S. mutans biofilm remains to be explored. In this study, the detection rate of C. albicans in caries-active (group CA) (22.03%) was significantly higher than that in caries-free (group CF) children (8.00%), and the expression of V-ATPase related genes were higher in group CA. Then, the higher expressed V-ATPase coding genes VMA3, VMA4 and VMA11 in CA group were knocked out. Compared with the wild type SC5314, the mutants showed slower growth rate, inhibited hyphal growth, and defective integrity of cell wall. The biofilm biomass and extracellular polysaccharide (EPS) production of dual biofilm were significantly reduced, and the biofilm structure was impacted. Transcriptome analysis indicated that V-ATPase participated in various metabolisms and biosynthesis pathways of C. albicans, and influenced EPS metabolism of S. mutans. Finally, compared with the positive control, the caries severity, the biomass and EPS production of dental plaque were significantly reduced after deletion of VMA3, VMA4 and VMA11 in vivo. This study revealed for the first time the regulating effect of V-ATPase on the cariogenicity of C. albicans-S. mutans biofilm and its potential mechanisms. The results may provide basis for new strategies of ecological prevention and treatment of dental caries.

Ribosome profiling reveals differences in global translational vs transcriptional gene expression changes during early Candida albicans biofilm formation

Candida albicans, a major human fungal pathogen, can form biofilms on a variety of inert and biological surfaces. C. albicans biofilms allow for immune evasion, are highly resistant to antifungal therapies, and represent a significant complication for a wide variety of immunocompromised patients in clinical settings. While transcriptional regulators and global transcriptional profiles of C. albicans biofilm formation have been well-characterized, much less is known about translational regulation of this important C. albicans virulence property. Here, using ribosome profiling, we define the first global translational profile of genes that are expressed during early biofilm development in a human fungal pathogen, C. albicans. We show that C. albicans biofilm formation involves altered translational regulation of genes and gene classes associated with protein synthesis, pathogenesis, transport, plasma membrane, polarized growth, cell cycle, secretion, and signal transduction. Interestingly, while similar, but not identical, classes of genes showed transcriptional alterations during early C. albicans biofilm development, we observed very little overlap between specific genes that are upregulated or downregulated at the translational vs transcriptional levels. Our results suggest that distinct translational mechanisms play an important role in regulating early biofilm development of a major human fungal pathogen. These mechanisms, in turn, could serve as potential targets for novel antifungal strategies.IMPORTANCEThe major human fungal pathogen Candida albicans is known to form biofilms or complex aggregated microbial communities encased in an extracellular matrix. These biofilms allow C. albicans to escape detection by the immune system as well as resist a variety of antifungal drugs. In this study, we define the first global profile of genes that show altered translation during C. albicans biofilm formation. These genes are involved in a variety of key cellular processes, including polarized growth, pathogenesis, transport, protein synthesis, cell cycle, plasma membrane, signal transduction, and secretion. Interestingly, while similar classes of genes are induced at both the transcriptional and translational levels during early C. albicans biofilm formation, we observed very little overlap among specific genes with altered transcription and translation. Our results suggest that C. albicans biofilm formation is controlled by distinct translational mechanisms, which could potentially be targeted by novel antifungal drugs.

Efficacy of nitrofuran derivatives against biofilms of Histoplasma capsulatum strains and their in vivo toxicity

AIM

To evaluate the efficacy of two nitrofuran derivatives against biofilms formed by two strains of Histoplasma capsulatum and to study the toxicity of these compounds in alternative models: Caenorhabditis elegans, Galleria mellonella, and zebrafish.

METHODS

The metabolic activity of biofilms was measured after treatment using the XTT reduction assay. Scanning electron microscopy (SEM) and confocal microscopy were used to observe damage to mature biofilms. Survival curves were generated for G. mellonella, while percentage survival was determined for C. elegans and zebrafish.

RESULTS

The compounds showed efficacy against early and mature biofilms at concentrations equal to or up to two times higher than those required to eliminate planktonic fungal cells (3.90 to 31.25 μg/mL). Micrographs showed a reduction in metabolic activity, biofilm thickness, and extracellular matrix. In addition, the compounds showed little or no toxicity in alternative models, even at the highest concentrations tested.

CONCLUSION

These results are promising for the development of new therapeutic alternatives, especially for species, such as H. capsulatum, which are recognized as high-priority pathogens. Few studies have investigated resistance and antifungal treatment targeting biofilms of this species, making this work a relevant contribution to future approaches.

Electrically-driven drug delivery into deep cutaneous tissue by conductive microneedles for fungal infection eradication and protective immunity

Fungal infections affect over 13 million people worldwide and are responsible for 1.5 million deaths annually. Some deep cutaneous fungal infections may extend the dermal barriers to cause systemic infection, resulting in substantial morbidity and mortality. However, the management of deep cutaneous fungal infection is challenging and yet overlooked by traditional treatments, which only offer limited drug availability within deep tissue. In this study, we have developed an electrically stimulated microneedle patch to deliver miconazole into the subcutaneous layer. We tested its antifungal efficacy using in vitro and ex vivo models that mimic fungal infection. Moreover, we confirmed its anti-fungal and wound-healing effects in a murine subcutaneous fungal infection model. Furthermore, our findings also showed that the combination of miconazole and applied current synergistically stimulated the nociceptive sensory nerves, thereby activating protective cutaneous immunity mediated by dermal dendritic and γδ-T cells. Collectively, this study provides a new strategy for minimally invasive delivery of therapeutic agents and the modulation of the neuro-immune axis in deep tissue.

Evaluation of biofilm formation and antimicrobial susceptibility (drug resistance) of Candida albicans isolates

Candida albicans comprises over 80% of isolates from all forms of human candidiasis. Biofilm formation enhances their capacity to withstand therapeutic treatments. In addition to providing protection, biofilm formation by C. albicans enhances its pathogenicity. Understanding the fundamental mechanisms underlying biofilm formation is crucial to advance our understanding and treatment of invasive Candida infections. An initial screening of 57 Candida spp. isolates using CHROMagar Candida (CHROMagar) media revealed that 46 were C. albicans. Of these, 12 isolates (33.3%) had the capacity to form biofilms. These 12 isolates were subjected to multiple biochemical and physiological tests, as well as 18 S rRNA sequencing, to confirm the presence of C. albicans. Upon analysis of their sensitivity to conventional antifungal agents, the isolates showed varying resistance to terbinafine (91.6%), voriconazole (50%), and fluconazole (42%). Among these, only CD50 showed resistance to all antifungal agents. Isolate CD50 also showed the presence of major biofilm-specific genes such as ALS3, EFG1, and BCR1, as confirmed by PCR. Exposure of CD50 to gentamicin-miconazole, a commonly prescribed drug combination to treat skin infections, resulted in elevated levels of gene expression, with ALS3 showing the highest fold increase. These observations highlight the necessity of understanding the proteins involved in biofilm formation and designing ligands with potential antifungal efficacy.

2-Chloromethyl anthraquinone inhibits Candida albicans biofilm formation by inhibiting the Ras1-cAMP-Efg1 pathway

Candida albicans is an opportunistic pathogen, and the formation of its biofilm makes it resistant to traditional antifungal therapy. Anthraquinones have universal antibacterial activity. We evaluated the inhibitory effects of 2-chloromethyl anthraquinone on C. albicans adhesion, mycelial morphology transformation, and biofilm formation. The results showed that 2-chloromethyl anthraquinone could inhibit C. albicans adhesion, mycelium formation, and biofilm formation in a dose-dependent manner at 2 μg/mL. In addition, 2-chloromethyl anthraquinone significantly inhibited the expression of biofilm formation-related genes in C. albicans, including ALS1, CPH1, ECE1, HWP1, TEC1, BCR1, and UME6. In addition, Ras1-cAMP-Efg1 pathway-related genes (RAC1, CYR1, and TPK2) were also significantly down-regulated, indicating that the inhibitory effect of 2-chloromethyl anthraquinone on C. albicans biofilms may be related to the Ras1-cAMP-Efg1 signaling pathway. In summary, the results of this study confirmed the inhibitory mechanism of 2-chloromethyl anthraquinone on the virulence factors of C. albicans, which laid a theoretical foundation for its use as an anti-biofilm agent against C. albicans.

Polymicrobial interactions of Helicobacter pylori and its role in the process of oral diseases

Objective

Helicobacter pylori (H. pylori) infection affects approximately 50% of the global population. The predominant route of H. pylori transmission is through the oral pathway, making the oral cavity highly significant in its infection. This review focuses on the relationship between H. pylori and oral diseases, the influence of H. pylori infection on the oral microbiota, and the potential mechanisms involving certain oral pathogens.

Method

To identify relevant studies, we conducted searches in PubMed, Google Scholar using keywords such as "Helicobacter pylori," "oral diseases, " "oral microorganisms, " without any date restrictions. The retrieved publications were subject to a review.

Results

H. pylori infection is positively correlated with the occurrence of various oral diseases, such as dental caries, periodontitis, and oral lichen planus. H. pylori may affect the oral microbiota through various mechanisms, and there exists an interactive relationship between H. pylori and oral bacteria, including Streptococcus, Porphyromonas gingivalis (P. gingivalis), and Candida albicans (C. albicans).

Conclusions

H. pylori infection has a close relationship with certain oral diseases. H. pylori modulates oral microflora diversity and structure, while eradication therapy and medications have varying impacts on oral microbiota.

Mechanisms of Azole Potentiation: Insights from Drug Repurposing Approaches

The emergence of azole resistance and tolerance in pathogenic fungi has emerged as a significant public health concern, emphasizing the urgency for innovative strategies to bolster the efficacy of azole-based treatments. Drug repurposing stands as a promising and practical avenue for advancing antifungal therapy, with the potential for swift clinical translation. This review offers a comprehensive overview of azole synergistic agents uncovered through drug repurposing strategies, alongside an in-depth exploration of the mechanisms by which these agents augment azole potency. Drawing from these mechanisms, we delineate strategies aimed at enhancing azole effectiveness, such as inhibiting efflux pumps to elevate azole concentrations within fungal cells, intensifying ergosterol synthesis inhibition, mitigating fungal cell resistance to azoles, and disrupting biological processes extending beyond ergosterol synthesis. This review is beneficial for the development of these potentiators, as it meticulously examines instances and provides nuanced discussions on the mechanisms underlying the progression of azole potentiators through drug repurposing strategies.

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.

Who arrived first? Priority effects on Candida albicans and Pseudomonas aeruginosa dual biofilms

Historical processes in community assembly, such as species arrival order, influence interactions, causing priority effects. Candida albicans and Pseudomonas aeruginosa often co-occur in biofilm-based infections of the skin, lungs, and medical devices. Their predominantly antagonistic relationship involves complex physical and chemical interactions. However, the presence and implications of priority effects among these microorganisms remain largely unexplored. Here, we investigate the presence and impact of priority effect in dual-species biofilms using clinical isolates. By varying inoculation order, we observe significant changes in biofilm composition, structure, virulence, and antimicrobial susceptibility. The first colonizer has an advantage for surface colonization. Consecutive colonization increases biofilm virulence and negates C. albicans' protective effect on P. aeruginosa PAET1 against meropenem treatment. Finally, we propose N-acetylcysteine as an adjuvant for treating C. albicans and P. aeruginosa interkingdom infections, working independently of priority effects.

Thiosemicarbazones and analogues as potential biofilm inhibitors of Candida albicans

Biofilms are a virulence factor for Candida albicans, a common pathogen in human fungal infections, making them resistant to many commercial antifungals. Therefore, the discovery of compounds that inhibit and eradicate biofilms is a priority. As thiosemicarbazones have had their effect on Candida biofilms little explored, this study investigated the inhibitory and eradication activity of 30 thiosemicarbazones and analogues against C. albicans biofilms. After initial screening, four compounds were selected and compound 28 emerged as the most potent with BIC50 at 31.55 ± 1.18 µM. By scanning electron microscopy analysis, blastoconidia adhered to the reduced surface and reduced formation of pseudohyphae and hyphae was revealed. Despite the inhibitory activity, the four compounds failed to eradicate the biofilm by more than 50%. Thus, the results suggest that the compounds evaluated are very promising for the development of effective antibiofilm compounds and open up new perspectives for elucidating the mechanism of action.

PPZ1-TORC1 pathway mediates ferroptosis and antifungal resistance in Candida albicans

Candida albicans (C. albicans), a common fungal pathogen, is responsible for infections such as oral candidiasis. Given the widespread misuse of antifungal medications and the increasing resistance, it is critical to explore new strategies to eradicate C. albicans. This study investigates ferroptosis, a form of cell death previously underexplored in fungi, focusing on the role of the fungus-specific protein phosphatase Z1 (PPZ1) in regulating the target of rapamycin complex 1 (TORC1) pathway during tert-butyl hydroperoxide (t-BuOOH)-induced ferroptosis. We demonstrated that ferroptosis induced by t-BuOOH promoted the accumulation of iron-dependent lipid peroxides, leading to the death of C. albicans. Furthermore, PPZ1 deletion impairs TORC1 signaling, activates autophagy, increases sensitivity to ferroptosis following t-BuOOH exposure, and reduces resistance to various antifungal drugs. These findings reveal the role of the PPZ1-TORC1 pathway in ferroptosis and provide a theoretical basis for developing ferroptosis as a novel antifungal strategy to eradicate C. albicans. The potential combined application of ferroptosis and antifungal drugs is expected to improve the efficacy of treating fungal infections.

Strain-limited biofilm regulation through the Brg1-Rme1 circuit in Candida albicans

Prominent virulence traits of Candida albicans include its ability to produce filamentous hyphal cells and grow as a biofilm. These traits are under control of numerous transcription factors (TFs), including Brg1 and Rme1. In the reference strain SC5314, a brg1Δ/Δ mutant has reduced levels of biofilm/filament production; a brg1Δ/Δ rme1Δ/Δ double mutant has wild-type levels of biofilm/filament production. Here, we asked whether this suppression relationship is preserved in four additional strain backgrounds: P76067, P57055, P87, and P75010. These strains represent diverse clades and biofilm/filament production abilities. We find that a rme1Δ/Δ mutation restores biofilm/filament production in a brg1Δ/Δ mutant of P76067, but not in brg1Δ/Δ mutants of P57055, P87, and P75010. We speculate that variation in activities of two functionally related TFs, Nrg1, and Ume6, may cause the strain-limited impact of the rme1Δ/Δ mutation.

IMPORTANCE

Candida albicans is a widespread fungal pathogen. The regulatory circuitry underlying virulence traits is well studied in the reference strain background, but not in other clinical isolate backgrounds. Here, we describe a pronounced example of strain variation in the control of two prominent virulence traits, biofilm formation and filamentation.

Innovative antifungal strategies: enhanced biofilm inhibition of Candida albicans by a modified tea tree oil formulation

Introduction

Candida albicans is a significant human pathogen with the ability to form biofilms, a critical factor in its resistance to antifungal treatments. This study aims to evaluate the antifungal activity and biofilm inhibition potential of Tea Tree Oil (TTO) derived from Melaleuca alternifolia cultivated in Vietnam.

Methods

The antifungal activity of TTO was assessed by determining the Minimum Inhibitory Concentration (MIC), Minimum Fungicidal Concentration (MFC), Minimum Biofilm Inhibitory Concentration (MBIC), and Minimum Biofilm Eradication Concentration (MBEC) using broth dilution methods. The experiments were conducted on C. albicans in both planktonic and biofilm states across concentrations ranging from 0.1 μL/mL to 10 μL/mL.

Results

TTO demonstrated significant antifungal efficacy, with a MIC of 0.1 μL/mL (∼91.217 μg/mL) and an MFC of 10 μL/mL (∼9121.7 μg/mL). It effectively inhibited biofilm formation with a recorded MBIC of 2 μL/mL (∼1824.34 μg/mL). However, MBEC values were not determinable as the concentrations tested did not achieve the eradication of more than 50% of mature biofilm within the experimental conditions.

Discussion

These findings highlight TTO as a promising natural antifungal agent with strong biofilm-inhibitory properties. However, its limited efficacy in eradicating mature biofilms underscores the need for further studies, potentially involving higher concentrations or synergistic combinations with conventional antifungal agents.

The mycobiome in human cancer: analytical challenges, molecular mechanisms, and therapeutic implications

The polymorphic microbiome is considered a new hallmark of cancer. Advances in High-Throughput Sequencing have fostered rapid developments in microbiome research. The interaction between cancer cells, immune cells, and microbiota is defined as the immuno-oncology microbiome (IOM) axis. Fungal microbes (the mycobiome), although representing only ∼ 0.1-1% of the microbiome, are a critical immunologically active component of the tumor microbiome. Accumulating evidence suggests a possible involvement of commensal and pathogenic fungi in cancer initiation, progression, and treatment responsiveness. The tumor-associated mycobiome mainly consists of the gut mycobiome, the oral mycobiome, and the intratumoral mycobiome. However, the role of fungi in cancer remains poorly understood, and the diversity and complexity of analytical methods make it challenging to access this field. This review aims to elucidate the causal and complicit roles of mycobiome in cancer development and progression while highlighting the issues that need to be addressed in executing such research. We systematically summarize the advantages and limitations of current fungal detection and analysis methods. We enumerate and integrate these recent findings into our current understanding of the tumor mycobiome, accompanied by the prospect of novel and exhilarating clinical implications.

Efficacy of lipid nanoparticles-based vaccine to protect against vulvovaginal candidiasis (VVC): Implications for women's reproductive health

AIMS

Vulvovaginal candidiasis (VVC) is a common women's health issue, with rising antifungal resistance. This study was aimed to prepare and evaluate the efficacy of a lipid nanoparticle-based vaccine in a murine model of VVC.

MATERIALS AND METHODS

Dried and reconstituted vesicles containing C. albicans antigens (DRNPs-Ca-Ags) vaccine, formulated with phosphatidylcholine and cholesterol-based lipid nanoparticles via film hydration and freeze-drying. The safety evaluation of DRNPs-CaAgs was conducted by determining hepatic (AST, ALT) or renal (BUN, creatinine) biomarkers. Female mice were immunized with DRNPs-CaAgs or Alum-CaAgs, and immune responses were evaluated via antibody titers, IgG isotypes, and splenocyte proliferation. Protective efficacy of vaccine formulations was assessed through fungal burden, biofilm formation, cytokine levels, and histopathological analysis of vaginal tissues.

KEY FINDINGS

Mice vaccinated with DRNPs-CaAgs showed significantly enhanced immune responses, with higher antibody titers and IgG2a levels as compared to the Alum-CaAgs group. Vaginal fungal burden was dramatically reduced (665 ± 78 CFUs in DRNPs-CaAgs immunized group vs. 12,944 ± 3540 CFUs in Alum-CaAgs group, p < 0.01). Biofilm formation decreased by 45 % (p < 0.05), and inflammatory cytokines were significantly lowered. Histopathological analysis revealed minimal tissue damage in DRNPs-CaAgs vaccinated mice.

SIGNIFICANCE

The findings suggest DRNPs-CaAgs as a promising vaccine for VVC, eliciting strong immunity, reducing fungal load, and minimizing inflammation. While the reliance on a murine model is a limitation, future clinical trials are essential to evaluate its efficacy and safety in humans, offering a potential strategy to combat drug-resistant infections and improve women's reproductive health.

Gelatin Nanoemulsion-Based Co-Delivery of Terbinafine and Essential Oils for Treatment of Candida albicans Biofilms

Fungal infections represent a significant global health challenge. Candida albicans is a particularly widespread pathogen, with both molecular and biofilm-based mechanisms making it resistant to or tolerant of available antifungal drugs. This study reports a combination therapy, active against C. albicans, utilizing terbinafine and essential oils incorporated into a gelatin-based nanoemulsion system (T-GNE). Eugenol and methyl eugenol/terbinafine T-GNEs had an additive efficacy, while carvacrol (CT-GNE) worked synergistically with terbinafine, providing effective antifungal treatment with minimal mammalian cell toxicity. Confocal microscopy demonstrated that CT-GNE penetrated the dense C. albicans biofilm and disrupted the fungal cell membrane. Overall, the combination of essential oils with terbinafine in GNE provided a promising treatment for fungal biofilms.

Miconazole-splitomicin combined β-glucan hydrogel for effective prevention of Candida albicans periprosthetic joint infection

As one of the most common and serious infections caused by Candida albicans (C. albicans), periprosthetic joint infection (PJI) increasingly concerns surgeons and scientists. Generally, biofilms shield C. albicans from antifungal agents and immune clearance and induce drug-resistant strains. Developing novel strategies for PJI to get rid of current drug-resistant problems is highly needed. In our study, splitomicin (SP) can inhibit the mycelium formation of C. albicans and enhance the drug sensitivity of C. albicans to miconazole nitrate (MCZ). The combination of SP and MCZ significantly inhibited the viability, proliferation and adhesion of C. albicans, reduced the yeast to hyphae transition and biofilm formation. When SP and MCZ were coloaded in the β-glucan hydrogel, a viscoelastic solid with porous 3D network, sustained release and erosion properties was obtained. In the in vivo PJI mice model, SP-MCZ-β-glucan hydrogel effectively reduced the colonization and aggregation of C. albicans around the implant, reduced the pathological changes caused by C. albicans in the femur tissue. Therefore, SP-MCZ-β-glucan hydrogel holds a great promise for the management of C. albicans infection around joint prosthesis.

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.

Antifungal activity of essential oils and their potential synergistic effect with amphotericin B

Candida albicans is a common opportunistic pathogen, causing infections ranging from superficial to bloodstream infections. The limited antifungal options and rising drug resistance challenge clinical treatment. We screened 98 essential oils and identified 48 with antifungal activity against Candida albicans at 1% concentration, determining their minimum inhibitory concentrations (MIC). Of these, 14 maintained fungicidal activity at lower concentrations (0.25% and 0.125%). 5 essential oils (Cinnamon, Satureja montana, Palmarosa, Lemon eucalyptus, and Honey myrtle) showed the highest inhibitory effects on stationary-phase Candida albicans and inhibited hyphae elongation. Synergistic effects were observed when combining Palmarosa with amphotericin B (AmB) against growing-phase Candida albicans, while Cinnamon and Satureja montana with AmB showed superior efficacy against stationary-phase infections. We identified the active components of 5 essential oils using gas chromatography-mass spectrometry (GC-MS) and found the following main constituents: Cinnamon primarily contains benzyl benzoate and eugenol, Satureja montana is dominated by carvacrol and cymene, Palmarosa features geraniol and geranyl acetate, Lemon eucalyptus includes dl-Isopulegol and citronellal, and Honey myrtle is characterized by citral and neral. Our results may aid in developing more effective antifungal treatments.

The Cwr1 protein kinase localizes to the plasma membrane and mediates resistance to cell wall stress in Candida albicans

The plasma membrane is critical for the virulence of the human fungal pathogen Candida albicans. In addition to functioning as a protective barrier, the plasma membrane plays dynamic roles in a wide range of functions needed for virulence including nutrient uptake, cell wall synthesis, morphogenesis, resistance to stress, and invasive hyphal growth. Screening a collection of C. albicans mutants identified an understudied gene that is important for invasive hyphal growth, which we have termed CWR1 (Cell Wall Regulatory kinase). A mutant strain lacking CWR1 displayed defects in resisting stressful conditions that exacerbate cell wall defects. The Cwr1 protein shows strong similarity to protein kinases, suggesting it plays a regulatory role in coordinating plasma membrane and cell wall functions. A Cwr1-green fluorescent protein (GFP) fusion protein localized to punctate patches associated with the plasma membrane that partially overlapped Membrane Compartment of Can1 (MCC)/eisosome domains. In contrast to the static MCC/eisosome domains, the Cwr1-GFP patches were very dynamic. Truncation mutants lacking C-terminal sequences distal to the protein kinase domain failed to show detectable localization at the plasma membrane. Surprisingly, these mutant strains did not show the defects of a cwr1Δ mutant, suggesting that localization to punctate patches associated with the plasma membrane is not essential for Cwr1 function. Altogether, these data indicate that Cwr1 contributes to the regulation of plasma membrane functions that promote proper morphogenesis and resistance to cell wall stress, both of which are important for C. albicans virulence.

IMPORTANCE

The ability of Candida albicans to grow invasively in the host and resist stress is critical for it to be an effective human pathogen. Identifying the genes that promote these processes is important for developing new strategies to block infection. Therefore, genetic methods were used in this study to identify a novel gene that is needed for invasive growth and stress resistance (Cell Wall Regulatory kinase [CWR1]). Interestingly, the Cwr1 protein localized to punctate patches in the plasma membrane, some of which co-localized with specialized subdomains of the plasma membrane known as eisosomes that are known to promote stress resistance and invasive growth in the host. Thus, these studies identified a novel regulator of traits that are critical for C. albicans pathogenesis.

Phenotypic and genotypic characterization of Candida species from the oral cavity of healthy individuals in Lublin province, Poland

Background

Candida spp., particularly C. albicans, are commonly isolated fungi in the oral cavity. However, their prevalence in healthy participants and their genotype-phenotype relation remains elusive.

Aim

This study aimed to update the information on Candida species colonizing the oral cavity of healthy population, identify the most common species, and characterize the intraspecific diversity to determine the genotype-phenotype relationship.

Methods

Oral swabs of healthy participants who declared an absence of oral infection were analyzed. Microbiological methods: chromogenic media, sugar assimilation tests, drug susceptibility, filamentation tests, temperature tolerance analysis, and assessment of biofilm formation ability. Genotyping methods: PCR amplification of the internal transcribed spacer (ITS) region with MspI restriction enzyme digestion and 25S rDNA region.

Results

Of the 500 individuals tested, 130 harbored C. albicans in 77%, C. dubliniensis in 12%, Pichia kudriavzevii (previously C. krusei) in 8%, and Nakaseomyces glabrata (previously C. glabrata) in 3%. The microbiological tests yielded conflicting results. Analysis of the 25S rDNA transposable intron region contributed to the identification of individual Candida spp. and intraspecific identification of C. albicans genotypes. Genotype A accounted for 70% (n = 100) of C. albicans isolates, whereas genotypes B, C, and D (C. dubliniensis) accounted for 17%, 9%, and 4% of the isolates, respectively.

Conclusion

The results indicate a complex genotype-phenotype relationship in Candida spp. and recommends combining microbiological and molecular methods for the efficient typing of Candida spp.

The Coexistence of Klebsiella pneumoniae and Candida albicans Enhanced Biofilm Thickness but Induced Less Severe Neutrophil Responses and Less Inflammation in Pneumonia Mice Than K. pneumoniae Alone

Due to the possible coexistence of Klebsiella pneumoniae (KP) and Candida albicans (CA), strains of KP and CA with biofilm production properties clinically isolated from patients were tested. The production of biofilms from the combined organisms (KP+CA) was higher than the biofilms from each organism alone, as indicated by crystal violet and z-stack immunofluorescence. In parallel, the bacterial abundance in KP + CA was similar to KP, but the fungal abundance was higher than CA (culture method), implying that CA grows better in the presence of KP. Proteomic analysis was performed to compare KP + CA biofilm to KP biofilm alone. With isolated mouse neutrophils (thioglycolate induction), KP + CA biofilms induced less prominent responses than KP biofilms, as determined by (i) neutrophilic supernatant cytokines (ELISA) and (ii) neutrophil extracellular traps (NETs), using immunofluorescent images (neutrophil elastase, myeloperoxidase, and citrullinated histone 3), peptidyl arginine deiminase 4 (PAD4) expression, and cell-free DNA. Likewise, intratracheal KP + CA in C57BL/6 mice induces less severe pneumonia than KP alone, as indicated by organ injury (serum creatinine and alanine transaminase) (colorimetric assays), cytokines (ELISA), bronchoalveolar lavage fluid parameters (bacterial culture and neutrophil abundances using a hemocytometer), histology score (H&E stains), and NETs (immunofluorescence on the lung tissue). In conclusion, the biofilm biomass of KP + CA was mostly produced from CA with less potent neutrophil activation and less severe pneumonia than KP alone. Hence, fungi in the respiratory tract might benefit the host in some situations, despite the well-known adverse effects of fungi.

The challenges and prospects of using cold plasma to prevent bacterial contamination and biofilm formation in the meat industry

The risk of foodborne disease outbreaks increases when the pathogenic bacteria are able to form biofilms, and this presents a major threat to public health. An emerging non-thermal cold plasma (CP) technology has proven a highly effective method for decontaminating meats and their products and extended their shelf life. CP treatments have ability to reduce microbial load and, biofilm formation with minimal change of color, pH value, and lipid oxidation of various meat and meat products. The CP technique offers many advantages over conventional processing techniques due to its layout flexibility, nonthermal behavior, affordability, and ecological sustainability. The technology is still in its infancy, and continuous research efforts are needed to realize its full potential in the meat industry. This review addresses the basic principles and the impact of CP technology on biofilm formation, meat quality (including microbiological, color, pH value, texture, and lipid oxidation), and microbial inactivation pathways and also the prospects of this technology.

Mining for antifungal agents to inhibit biofilm formation of Candida albicans: A study on green synthesis, antibiofilm, cytotoxicity, and in silico ADME analysis of 2-amino-4H-pyran-3-carbonitrile derivatives

Candida albicans (C. albicans) biofilm infections are quite difficult to manage due to their resistance against conventional antifungal drugs. To address this issue, there is a desperate need for new therapeutic drugs. In the present study, a green and efficient protocol has been developed for the synthesis of 2-amino-4H-pyran-3-carbonitrile scaffolds 4a-i, 6a-j, and 8a-g by Knoevenagel-Michael-cyclocondensation reaction between aldehydes, malononitrile, and diverse enolizable C-H activated acidic compounds using guanidinium carbonate as a catalyst either under grinding conditions or by stirring at room temperature. This protocol is operationally simple, rapid, inexpensive, has easy workup and column-free purification. A further investigation of the synthesized compounds was conducted to examine their antifungal potential and their ability to inhibit the growth and development of biofilm-forming yeasts like fungus C. albicans. According to our findings, 4b, 4d, 4e, 6e, 6f, 6g, 6i, 8c, 8d, and 8g were found to be active and potential inhibitors for biofilm infection causing C. albicans. The inhibition of biofilm by active compounds were observed using field emission scanning electron microscopy (FESEM). Biofilm inhibiting compounds were also tested for in vitro toxicity by using 3T3-L1 cell line, and 4b, 6e, 6f, 6g, 6i, 8c, and 8d were found to be biocompatible. Furthermore, the in silico ADME descriptors revealed drug-like properties with no violation of Lipinski's rule of five. Hence, the result suggested that synthesized derivatives could serve as a useful aid in the development of novel antifungal compounds for the treatment of fungal infections and virulence in C. albicans.

Characterization of a New Hsp110 Inhibitor as a Potential Antifungal

Fungal infections present a significant global health challenge, prompting ongoing research to discover innovative antifungal agents. The 110 kDa heat shock proteins (Hsp110s) are molecular chaperones essential for maintaining cellular protein homeostasis in eukaryotes. Fungal Hsp110s have emerged as a promising target for innovative antifungal strategies. Notably, 2H stands out as a promising candidate in the endeavor to target Hsp110s and combat fungal infections. Our study reveals that 2H exhibits broad-spectrum antifungal activity, effectively disrupting the in vitro chaperone activity of Hsp110 from Candida auris and inhibiting the growth of Cryptococcus neoformans. Pharmacokinetic analysis indicates that oral administration of 2H may offer enhanced efficacy compared to intravenous delivery, emphasizing the importance of optimizing the AUC/MIC ratio for advancing its clinical therapy.

Improving the Bioactivity and Antibiofilm Properties of Metallic Implant Materials via Controlled Surface Microdeformation

Although metallic implants provide most of the required properties for bone-related applications, especially orthopedic implants, insufficient osseointegration, which may lead to loosening of the implant or prolonged healing time, is still an issue to be resolved. Osseointegration can be improved via application of various surface treatments on the metal surface. The current study focuses on a novel surface microdeformation method, which enables the formation of controlled surface patterns of various parameters. With this purpose, a surface microdeformation procedure was applied on 316L stainless steel surfaces, forming four different patterns which affected various surface parameters such as roughness, surface energy, dislocation activities close to the surface, and wettability. Static immersion tests in a simulated body fluid (SBF) environment showed that modifying the surface parameters via controlled surface patterning promoted the formation of a stable oxide layer and calcium-phosphate (CaP) deposition on the metal surfaces, improving bioactivity. Moreover, the higher amount of CaP deposition and oxide layer formation on the modified surfaces led to reduced ion release, which contributed to improved corrosion resistance. Finally, the effect of the formed surface patterns on antibiofilm formation was investigated via incubation with C. albicans for 24 h, which exhibited that microdeformation patterns remarkably inhibited the biofilm formation. Throughout the experiments, certain patterns yielded outstanding results among the four patterns formed. Overall, it was concluded that forming controlled patterns on stainless steel surfaces via surface microdeformation significantly contributed to the metal's biocompatibility via improving bioactivity, corrosion resistance, and antibiofilm formation properties. Especially, the specific surface properties such as increased surface energy, high surface roughness, and dislocation density close to the metal surface as well as increased hydrophilicity obtained via forming the pattern with relatively deeper and narrowly spaced indents yielded the most promising outcomes. These methodologies constitute novel approaches to be used while designing new methodologies for the surface modification of metallic implant materials for improved osseointegration.

Contact lenses as a potential vehicle of Candida transmission

PURPOSE

Contact lenses can be contaminated with various microorganisms, including pathogenic yeasts of the genus Candida, which are known for their ability to adhere to abiotic surfaces, including plastic materials used for various medical purposes. Microbial contamination of the lenses can lead to infection of the wearer's eyes. The purpose of this study was to simulate the contamination of contact lenses with C. albicans and C. parapsilosis, analyze the interaction of the microorganisms with the lens material, and optimize the protocol for PCR-based analysis of the microbial agents responsible for lens contamination.

METHODS

Hilafilcon lenses were exposed to C. albicans and C. parapsilosis cultures, washed, and examined for their ability to further spread the contamination. Scanning electron microscopy was used to analyze the attachment of yeast cells to the lenses. Infrared spectroscopy was used to examine the potential changes in the lens material due to Candida contamination. The protocol for DNA isolation from contaminated lenses was established to enable PCR analysis of microbes attached to the lenses.

RESULTS

Hilafilcon lenses contaminated with Candida were able to spread the contamination even after washing with saline or with a commercial cleaning solution. In the present experimental settings, the yeasts did not grow into the lenses but began to form biofilms on the surface. However, the ability of the lenses to retain water was altered. The PCR-based protocol could be used to help identify the type of contamination of contact lenses.

CONCLUSION

Once contaminated with Candida albicans or Candida parapsilosis, Hilafilcon contact lenses are difficult to clean. Yeasts began to form biofilms on lens surfaces.

Clinical aPDT's effect on Candida albicans: Antifungal susceptibility, virulence gene expression, and correlation with leukocyte and neutrophil counts

BACKGROUND

Our previous clinical trial demonstrated that antimicrobial photodynamic therapy (aPDT) with methylene blue (MB) and potassium iodide (KI) effectively killed Candida albicans (C. albicans) in adult AIDS patients with oral candidiasis, regardless of biofilm formation or 25S rDNA genotype. This study evaluated changes in antifungal susceptibility and virulence gene expression in C. albicans before and after aPDT, and explored factors related to clinical aPDT efficacy.

METHODS

Twenty-one adult AIDS patients with C. albicans oral candidiasis were divided into Group a (400 μM MB, N = 11) and Group b (600 μM MB, N = 10). Both groups received two aPDT treatments, where MB was applied for 5 min, followed by 300 mM KI, and illuminated for 30 min (37.29 J/cm²). C. albicans isolates were collected before and after treatment to assess antifungal susceptibility (fluconazole, itraconazole, flucytosine, amphotericin B) and gene expression (CAT1, HWP1). Peripheral blood tests were analyzed for correlations with aPDT efficacy.

RESULTS

aPDT reduced minimum inhibitory concentration (MIC) values for amphotericin B, fluconazole, and flucytosine, with significant reductions primarily after the first treatment. MIC reductions differed between groups, with Group a showing greater decreases in flucytosine and fluconazole MICs, and Group b in amphotericin B MICs. No significant changes in CAT1 or HWP1 expression were observed. Clinical efficacy of aPDT negatively correlated with leukocyte and neutrophil levels.

CONCLUSIONS

aPDT effectively reduces MICs of antifungal drugs against C. albicans isolated from treated patients, particularly after the first treatment. The concentration of MB required to reduce MICs varies among different antifungal drugs. aPDT does not alter CAT1 or HWP1 expression, and its clinical efficacy in eradicating C. albicans is negatively associated with leukocyte and neutrophil levels.

Antibiotics stimulates the development of persistent cells in biofilms of Candida albicans bloodstream isolates

Candida albicans invasive candidiasis is considered a global health problem. In such cases, biofilm formation on implanted devices represents a therapeutic challenge and the presence of metabolically inactive persistent cells (PCs) in these communities increases their tolerance to fungicidal drugs. This study investigated the influence of amoxicillin, AMX; cefepime, CEF; gentamicin, GEN; amikacin, AMK; vancomycin, VAN; and ciprofloxacin, CIP; on the production of PCs in biofilms of C. albicans bloodstream isolates. 48 h-mature biofilms (n = 6) grown in RPMI-1640 supplemented with antibiotics were treated with 100 μg ml-1 amphotericin B and then evaluated for PCs. Biofilms grown in the presence of antibiotics produced more PCs, up to 10×, when exposed to AMX and CIP; 5 × to CEF; and 6 × to GEN and VAN. The results indicate that antibiotics can modulate PC production in C. albicans biofilms. This scenario may have clinical repercussions in immunocompromised patients under broad-spectrum antibiotic therapy.

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

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

Recent Challenges in Diagnosis and Treatment of Invasive Candidiasis in Neonates

Invasive Candida infections represent a significant cause of morbidity and mortality in the neonatal intensive care unit (NICU), particularly among preterm and low birth weight neonates. The nonspecific clinical presentation of invasive candidiasis, resembling that of bacterial sepsis with multiorgan involvement, makes the diagnosis challenging. Given the atypical clinical presentation and the potential detrimental effects of delayed treatment, empirical treatment is often initiated in cases with high clinical suspicion. This underscores the need to develop alternative laboratory methods other than cultures, which are known to have low sensitivity and a prolonged detection time, to optimize therapeutic strategies. Serum biomarkers, including mannan antigen/anti-mannan antibody and 1,3-β-D-glucan (BDG), both components of the yeast cell wall, a nano-diagnostic method utilizing T2 magnetic resonance, and Candida DNA detection by PCR-based techniques have been investigated as adjuncts to body fluid cultures and have shown promising results in improving diagnostic efficacy and shortening detection time in neonatal populations. This review aims to provide an overview of the diagnostic tools and the current management strategies for invasive candidiasis in neonates. Timely and accurate diagnosis followed by targeted antifungal treatment can significantly improve the survival and outcome of neonates affected by Candida species.

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.

Study on the chemical composition and anti-fungi activities of anthraquinones and its glycosides from Rumex japonicus Houtt

Fungi, such as Trichophyton rubrum (T. rubrum) and Microsporum canis Bodin Anamorph (M. canis Bodin Anamorph) are the main pathogens of dermatophysis. According to ancient books records, Rumex japonicus Houtt. (RJH) has a miraculous effect on the treatment of dermatophysis. To reveal the anti-fungi (T. rubrum and M. canis Bodin Anamorph) components and its mechanism of the Rumex japonicus Houtt. The vinegar extraction and alcohol precipitation, HPLC and nuclear magnetic resonance spectroscopy (NMR) were employed for analyzing the chemical compositions of RJH; in vitro anti-fungal experiment was investigated including test the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC), spore germination rate, nucleic acid, protein leakage rate, biofilm structure, and the mechanism of anti-fungal and anti-fungal biofilms in RJH. Seven anthraquinones and their glycoside compounds were obtained in this study respectively, such as chrysophanol, physcion, aloe-emodin, emodin, rhein, emodin-8-O-β-D-glucoside and chrysophanol-8-O-β-D-glucoside. In vitro anti-fungal experiment results showed that RJH extracts have good anti-fungal activity for dermatophytic fungi. Among them, the MIC of the rhein, emodin and aloe-emodin against T. rubrum are 1.9 µg/ml, 3.9 µg/ml and 15.6 µg/ml, respectively; the MIC of emodin and aloe-emodin against M. canis Bodin Anamorph are 7.8 µg/ml and 62.5 µg/ml, respectively. In addition, its active components can inhibit fungal spore germination and the formation of bud tube, change cell membrane permeability, prevent hyphal growth, destroy biofilm structure, and down-regulate the expression of agglutinin-like sequence family 1 of the adhesion phase of biofilm growth. The study shows that RJH play a fungicidal role.

Antifungal, molecular docking and cytotoxic effect of the essential oil of Cymbopogon citratus (DC) Stapf. and Cymbopogon nardus (L.) Rendle against Candida albicans

Brazil is renowned for its extensive plant biodiversity, with emphasis on Cymbopogon, C. citratus and C. nardus, with broad antimicrobial potential. Candidemias caused by Candida albicans are highly prevalent in immunosuppressed individuals and are associated with infections by biofilms on medical devices. The aim of this study was to evaluate the antimicrobial potential of essential oils C. citratus and C. nardus against C. albicans in planktonic and biofilm forms. Essential oils were obtained by hydrodistillation and chemical composition evaluated by GC-FID and GC-MS. The minimum inhibitory concentration was determined by the broth microdilution method and the synergy effect of essential oils and amphotericin B were evaluated by the checkerboard test. Biofilm activity was determined by the XTT assay. Cytotoxicity assays performed with VERO cells and molecular docking were performed to predict the effect of oil interaction on the SAP-5 enzyme site. The results showed activity of essential oils against planktonic cells and biofilm of C. albicans. Furthermore, the oils had a synergistic effect, and low cytotoxicity. Molecular docking showed interaction between Cadinene, Caryophyllen oxide, Germacrene D with SAP-5. The results indicate that Cymbopogon spp. studied are anti-Candida, with potential for further application in therapy against infections caused by C. albicans.

Nanorobots to Treat Candida albicans Infection

Candida albicans is an opportunistic fungal pathogen of humans. It causes a variety of infections ranging from superficial mucocutaneous conditions to severe systemic diseases that result in substantial morbidity and mortality. This pathogen frequently forms biofilms resistant to antifungal drugs and the host immune system, leading to treatment failures. Recent research has demonstrated the potential of nanorobots to penetrate biological barriers and disrupt fungal biofilms. In this perspective paper, we provide a brief overview of recent breakthroughs in nanorobots for candidiasis treatment and discuss current challenges and prospects.

The Candida albicans quorum-sensing molecule farnesol alters sphingolipid metabolism in human monocyte-derived dendritic cells

Candida albicans, an opportunistic fungal pathogen, produces the quorum-sensing molecule farnesol, which we have shown alters the transcriptional response and phenotype of human monocyte-derived dendritic cells (DCs), including their cytokine secretion and ability to prime T cells. This is partially dependent on the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ), which has numerous ligands, including the sphingolipid metabolite sphingosine 1-phosphate. Sphingolipids are a vital component of membranes that affect membrane protein arrangement and phagocytosis of C. albicans by DCs. Thus, we quantified sphingolipid metabolites in monocytes differentiating into DCs by High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Farnesol increased the activity of serine palmitoyltransferase, leading to increased levels of 3-keto-dihydrosphingosine, dihydrosphingosine, and dihydrosphingosine 1-phosphate and inhibited dihydroceramide desaturase by inducing oxidative stress, leading to increased levels of dihydroceramide and dihydrosphingomyelin species and reduced ceramide levels. Accumulation of dihydroceramides can inhibit mitochondrial function; accordingly, farnesol reduced mitochondrial respiration. Dihydroceramide desaturase inhibition increases lipid droplet formation, which we observed in farnesol-treated cells, coupled with an increase in intracellular triacylglycerol species. Furthermore, inhibition of dihydroceramide desaturase with either farnesol or specific inhibitors impaired the ability of DCs to prime interferon-γ-producing T cells. The effect of farnesol on sphingolipid metabolism, triacylglycerol synthesis, and mitochondrial respiration was not dependent on PPAR-γ. In summary, our data reveal novel effects of farnesol on sphingolipid metabolism, neutral lipid synthesis, and mitochondrial function in DCs that affect their instruction of T cell cytokine secretion, indicating that C. albicans can manipulate host cell metabolism via farnesol secretion.IMPORTANCECandida albicans is a common commensal yeast, but it is also an opportunistic pathogen which is one of the leading causes of potentially lethal hospital-acquired infections. There is growing evidence that its overgrowth in the gut can influence diseases as diverse as alcohol-associated liver disease and COVID-19. Previously, we found that its quorum-sensing molecule, farnesol, alters the phenotype of dendritic cells differentiating from monocytes, impairing their ability to drive protective T cell responses. Here, we demonstrate that farnesol alters the metabolism of sphingolipids, important structural components of the membrane that also act as signaling molecules. In monocytes differentiating to dendritic cells, farnesol inhibited dihydroceramide desaturase, resulting in the accumulation of dihydroceramides and a reduction in ceramide levels. Farnesol impaired mitochondrial respiration, known to occur with an accumulation of dihydroceramides, and induced the accumulation of triacylglycerol and oil bodies. Inhibition of dihydroceramide desaturase resulted in the impaired ability of DCs to induce interferon-γ production by T cells. Thus, farnesol production by C. albicans could manipulate the function of dendritic cells by altering the sphingolipidome.

An Insight into Rational Drug Design: The Development of In-House Azole Compounds with Antimicrobial Activity

Antimicrobial resistance poses a major threat to global health as the number of efficient antimicrobials decreases and the number of resistant pathogens rises. Our research group has been actively involved in the design of novel antimicrobial drugs. The blueprints of these compounds were azolic heterocycles, particularly thiazole. Starting with oxadiazolines, our research group explored, one by one, the other five-membered heterocycles, developing more or less potent compounds. An overview of this research activity conducted by our research group allowed us to observe an evolution in the methodology used (from inhibition zone diameters to minimal inhibitory concentrations and antibiofilm potential determination) correlated with the design of azole compounds based on results obtained from molecular modeling. The purpose of this review is to present the development of in-house azole compounds with antimicrobial activity, designed over the years by this research group from the departments of Pharmaceutical and Therapeutical Chemistry in Cluj-Napoca.

Invasive Candida Infections in Neonatal Intensive Care Units: Risk Factors and New Insights in Prevention

Invasive Candida infections represent a significant cause of morbidity and mortality in neonatal intensive care units (NICUs), with a particular impact on preterm and low-birth-weight neonates. In addition to prematurity, several predisposing factors for Candida colonization and dissemination during NICU hospitalization have been identified, including prolonged exposure to broad-spectrum antibiotics, central venous catheters, parenteral nutrition, corticosteroids, H2 antagonist administration, and poor adherence to infection control measures. According to the literature, the implementation of antifungal prophylaxis, mainly fluconazole, in high-risk populations has proven to be an effective strategy in reducing the incidence of fungal infections. This review aims to provide an overview of risk factors for invasive Candida infections and current perspectives regarding antifungal prophylaxis use. Recognizing and reducing people's exposure to these modifiable risk factors, in conjunction with the administration of antifungal prophylaxis, has been demonstrated to be an effective method for preventing invasive candidiasis in susceptible neonatal populations.