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

Correlation analysis of vaginal microecology and different types of human papillomavirus infection: a study conducted at a hospital in northwest China

Background

Vaginal microecology has a definite influence on human papillomavirus (HPV) infection and clearance, but the specific correlation is still controversial. This research aimed to investigate the differences in the vaginal microenvironment of different types of HPV infection and also provide data supporting clinical diagnosis and treatment.

Methods

According to strict inclusion and exclusion criteria, the case data of 2,358 female patients who underwent vaginal microecology and HPV-DNA tests at the same time in the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Xi'an Jiaotong University from May 2021 to March 2022 were retrospectively analyzed. The population was divided into two groups: an HPV-positive group and an HPV-negative group. HPV-positive patients were further classified into HPV16/18-positive group and HPV other subtypes positive group. The vaginal microecology of HPV-infected patients was analyzed using the chi-square test, Fisher's exact test, and logistic regression.

Results

Among the 2,358 female patients, the HPV infection rate was 20.27% (478/2,358), of which the HPV16/18 infection rate was 25.73% (123/478), and the HPV other subtypes infection rate was 74.27% (355/478). The difference in HPV infection rates between the age groups was statistically significant (P < 0.01). The prevalence of mixed vaginitis was 14.37% (339/2,358), with bacterial vaginosis (BV) paired with aerobic vaginitis (AV) accounting for the majority (66.37%). The difference in HPV infection rates among mixed vaginitis was not statistically significant (P > 0.05). The prevalence of single vaginitis was 24.22% (571/2,358), with the most frequent being vulvovaginal Candidiasis (VVC; 47.29%, 270/571), and there was a significant difference in HPV infection rates among single vaginitis (P < 0.001). Patients with BV had a higher risk of being positive for HPV16/18 (OR: 1.815, 95% CI: 1.050-3.139) and other subtypes (OR: 1.830, 95% CI: 1.254-2.669). Patients with Trichomoniasis were at higher odds of other HPV subtype infections (OR: 1.857, 95% CI: 1.004-3.437). On the contrary, patients with VVC had lower odds of becoming infected with other HPV subtypes (OR: 0.562, 95% CI: 0.380-0.831).

Conclusion

There were disparities in HPV infection among different age groups; therefore, we should pay attention to the prevention and treatment of susceptible individuals. BV and Trichomoniasis are linked to HPV infection; hence, restoring the balance of vaginal microecology could assist in the prevention of HPV infection. As a protective factor for other HPV subtype infections, VVC may provide new insights into the development of immunotherapeutic therapies.

Relationships between Secreted Aspartyl Proteinase 2 and General Control Nonderepressible 4 gene in the Candida albicans resistant to itraconazole under planktonic and biofilm conditions

This study aimed to explore the roles of SAP2 and GCN4 in itraconazole (ITR) resistance of C. albicans under different conditions, and their correlations. A total of 20 clinical strains of C. albicans, including 10 ITR resistant strains and 10 sensitive strains, were used. Then, SAP2 sequencing and GCN4 sequencing were performed, and the biofilm formation ability of different C. albicans strains was determined. Finally, real-time quantitative PCR was used to measure the expression of SAP2 and GCN4 in C. albicans under planktonic and biofilm conditions, as well as their correlation was also analyzed. No missense mutations and three synonymous mutation sites, including T276A, G543A, and A675C, were found in SAP2 sequencing. GCN4 sequencing showed one missense mutation site (A106T (T36S)) and six synonymous mutation sites (A147C, C426T, T513C, T576A, G624A and C732T). The biofilm formation ability of drug-resistant C. albicans strains was significantly higher than that of sensitive strains (P < 0.05). Additionally, SAP2 and GCN4 were up-regulated in the ITR-resistant strains, and were both significantly higher in C. albicans under biofilm condition. The mRNA expression levels of SAP2 and GCN4 had significantly positive correlation. The higher expression levels of SAP2 and GCN4 were observed in the ITR-resistant strains of C. albicans under planktonic and biofilm conditions, as well as there was a positive correlation between SAP2 and GCN4 mRNA expression.

Yeast biofilms on abiotic surfaces: Adhesion factors and control methods

Biofilms are highly resistant to antimicrobials and are a common problem in many industries, including pharmaceutical, food and beverage. Yeast biofilms can be formed by various yeast species, including Candida albicans, Saccharomyces cerevisiae, and Cryptococcus neoformans. Yeast biofilm formation is a complex process that involves several stages, including reversible adhesion, followed by irreversible adhesion, colonization, exopolysaccharide matrix formation, maturation and dispersion. Intercellular communication in yeast biofilms (quorum-sensing mechanism), environmental factors (pH, temperature, composition of the culture medium), and physicochemical factors (hydrophobicity, Lifshitz-van der Waals and Lewis acid-base properties, and electrostatic interactions) are essential to the adhesion process. Studies on the adhesion of yeast to abiotic surfaces such as stainless steel, wood, plastic polymers, and glass are still scarce, representing a gap in the field. The biofilm control formation can be a challenging task for food industry. However, some strategies can help to reduce biofilm formation, such as good hygiene practices, including regular cleaning and disinfection of surfaces. The use of antimicrobials and alternative methods to remove the yeast biofilms may also be helpful to ensure food safety. Furthermore, physical control measures such as biosensors and advanced identification techniques are promising for yeast biofilms control. However, there is a gap in understanding why some yeast strains are more tolerant or resistant to sanitization methods. A better understanding of tolerance and resistance mechanisms can help researchers and industry professionals to develop more effective and targeted sanitization strategies to prevent bacterial contamination and ensure product quality. This review aimed to identify the most important information about yeast biofilms in the food industry, followed by the removal of these biofilms by antimicrobial agents. In addition, the review summarizes the alternative sanitizing methods and future perspectives for controlling yeast biofilm formation by biosensors.

Candida albicans Adhesins Als1 and Hwp1 Modulate Interactions with Streptococcus mutans

Candida albicans and Streptococcus mutans are known to synergistically interact with each other in the oral cavity. For example, glucosyltransferase B (GtfB), secreted by S. mutans, can bind to the C. albicans cell surface, promoting dual-species biofilm formation. However, the fungal factors mediating interactions with S. mutans are unknown. The C. albicans adhesins Als1, Als3, and Hwp1 are key players in C. albicans single-species biofilm formation, but their roles, if any, in interacting with S. mutans have not been assessed. Here, we investigated the roles of the C. albicans cell wall adhesins Als1, Als3, and Hwp1 on forming dual-species biofilms with S. mutans. We assessed the abilities of the C. albicans wild-type als1Δ/Δ, als3Δ/Δ, als1Δ/Δ/als3Δ/Δ, and hwp1Δ/Δ strains to form dual-species biofilms with S. mutans by measuring optical density, metabolic activity, cell enumeration, biomass, thickness, and architecture of the biofilms. We observed that the C. albicans wild-type strain formed enhanced dual-species biofilms in the presence of S. mutans in these different biofilm assays, confirming that C. albicans and S. mutans synergistically interact in the context of biofilms. Our results reveal that C. albicans Als1 and Hwp1 are major players in interacting with S. mutans, since dual-species biofilm formation was not enhanced when the als1Δ/Δ or hwp1Δ/Δ strains were cultured with S. mutans in dual-species biofilms. Als3, however, does not seem to play a clear role in interacting with S. mutans in dual-species biofilm formation. Overall, our data suggest that the C. albicans adhesins Als1 and Hwp1 function to modulate interactions with S. mutans and could be potential targets for future therapeutics.

A first-in-class inhibitor of Hsp110 molecular chaperones of pathogenic fungi

Proteins of the Hsp110 family are molecular chaperones that play important roles in protein homeostasis in eukaryotes. The pathogenic fungus Candida albicans, which causes infections in humans, has a single Hsp110, termed Msi3. Here, we provide proof-of-principle evidence supporting fungal Hsp110s as targets for the development of new antifungal drugs. We identify a pyrazolo[3,4-b] pyridine derivative, termed HLQ2H (or 2H), that inhibits the biochemical and chaperone activities of Msi3, as well as the growth and viability of C. albicans. Moreover, the fungicidal activity of 2H correlates with its inhibition of in vivo protein folding. We propose 2H and related compounds as promising leads for development of new antifungals and as pharmacological tools for the study of the molecular mechanisms and functions of Hsp110s.

Bacterial-fungal interactions and their impact on microbial pathogenesis

Microbial communities of the human microbiota exhibit diverse effects on human health and disease. Microbial homeostasis is important for normal physiological functions and changes to the microbiota are associated with many human diseases including diabetes, cancer, and colitis. In addition, there are many microorganisms that are either commensal or acquired from environmental reservoirs that can cause diverse pathologies. Importantly, the balance between health and disease is intricately connected to how members of the microbiota interact and affect one another's growth and pathogenicity. However, the mechanisms that govern these interactions are only beginning to be understood. In this review, we outline bacterial-fungal interactions in the human body, including examining the mechanisms by which bacteria govern fungal growth and virulence, as well as how fungi regulate bacterial pathogenesis. We summarize advances in the understanding of chemical, physical, and protein-based interactions, and their role in exacerbating or impeding human disease. We focus on the three fungal species responsible for the majority of systemic fungal infections in humans: Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus. We conclude by summarizing recent studies that have mined microbes for novel antimicrobials and antivirulence factors, highlighting the potential of the human microbiota as a rich resource for small molecule discovery.

Psychrophilic and mesophilic anaerobic treatment of synthetic dairy wastewater with long chain fatty acids: Process performances and microbial community dynamics

Facilitating the anaerobic degradation of long chain fatty acids (LCFA) is the key to unlock the energy potential of lipids-rich wastewater. In this study, the feasibility of psychrophilic anaerobic treatment of LCFA-containing dairy wastewater was assessed and compared to mesophilic anaerobic treatment. The results showed that psychrophilic treatment at 15 ℃ was feasible for LCFA-containing dairy wastewater, with high removal rates of soluble COD (>90%) and LCFA (∼100%). However, efficient long-term treatment required prior acclimation of the biomass to psychrophilic temperatures. The microbial community analysis revealed that putative syntrophic fatty acid bacteria and Methanocorpusculum played a crucial role in LCFA degradation during both mesophilic and psychrophilic treatments. Additionally, a fungal-bacterial biofilm was found to be important during the psychrophilic treatment. Overall, these findings demonstrate the potential of psychrophilic anaerobic treatment for industrial wastewaters and highlight the importance of understanding the microbial communities involved in the process.

Rapid Inactivation of mixed biofilms of Candida albicans and Candida tropicalis using antibacterial photodynamic therapy: Based on PAD™ Plus

Background

To investigate the sterilizing effect of antimicrobial photodynamic therapy (aPDT) based on PAD™ Plus on mixed biofilms of Candida albicans and Candida tropicalis.

Methods

A mature mixed biofilm model of C. albicans and C. tropicalis was constructed in vitro. FITC-concanavalin A staining was conducted to observe the formation of the extracellular matrix. MTT assay was performed to determine biofilm viability. The chromogenic medium was used to examine the Candida composition of the mixed biofilms. For aPDT treatment, based on PAD™ Plus, the biofilms were incubated with 1 mg/mL TBO for 1, 5, or 10 min, followed by 500 or 750 mW LED illumination for 1 or 2 min. The live/dead fungi were detected by SYTO9/propidium iodide staining. A multivariate factorial design was conducted to analyze the correlations of parameters with the inactivation effect of the mixed biofilms.

Results

Mature mixed biofilms formed at 24 h after seeding. Compared with untreated biofilms, following 1-min TBO incubation, 500 mW LED illumination for 1 min inactivated more than 90% of the fungi. Extending the incubation time did not significantly improve the inactivation effect. Application of 750 mW output power or 2 min LED illumination inactivated more than 99% of the fungi without increasing other parameters.

Conclusions

PAD™ Plus combined with 1 mg/mL TBO can rapidly inactivate the mature mixed biofilms of C. albicans and C. tropicalis, serving as a robust platform for the treatment of mixed infections of C. albicans and C. tropicalis.

Candida Species in Children Undergoing Orthodontic Treatment with Removable Appliances: A Pilot Study

The purpose of this study was to analyze the effect of orthodontic treatment with removable appliances on the growth of Candida spp. in children undergoing orthodontic treatment. The study included 60 patients of equal numbers as to gender from the orthodontics department of the Pomeranian Medical University in Szczecin, Poland. All patients were aged 6-12 years and were qualified for orthodontic treatment with removable appliances. The following examinations were performed on the day of treatment initiation (T1) and 6 months after the start of treatment (T2); a collection of oral swabs for culture on Sabouraud's medium and the identification of fungal colonies using the VITEK^®2 YST. At T1, 42 (70%) subjects, were free of Candida, while after 6 months of treatment, the number decreased to 25 (41.67%). Two types of fungi, C. albicans and C. parapsilosis, predominated in the test performed at T1. The study at T2 showed that C. albicans most frequently colonized the oral cavity in 23 children (38.33%). Three new strains C. dubliniensis, C. kefyr, and C. krusei were identified at T2. Statistical analysis showed a significant correlation between the culture results and the age of the patient at T2. Patients older than 9 years had significantly more positive tests. Orthodontic treatment with removable appliances contributes to increased oral colonization by Candida spp.

Human Tooth as a Fungal Niche: Candida albicans Traits in Dental Plaque Isolates

Candida albicans, a fungus typically found in the mucosal niche, is frequently detected in biofilms formed on teeth (dental plaque) of toddlers with severe childhood caries, a global public health problem that causes rampant tooth decay. However, knowledge about fungal traits on the tooth surface remains limited. Here, we assess the phylogeny, phenotype, and interkingdom interactions of C. albicans isolated from plaque of diseased toddlers and compare their properties to reference strains, including 529L (mucosal isolate). C. albicans isolates exhibit broad phenotypic variations, but all display cariogenic traits, including high proteinase activity, acidogenicity, and acid tolerance. Unexpectedly, we find distinctive variations in filamentous growth, ranging from hyphal defective to hyperfilamentous. We then investigate the ability of tooth isolates to form interkingdom biofilms with Streptococcus mutans (cariogenic partner) and Streptococcus gordonii (mucosal partner). The hyphal-defective isolate lacks cobinding with S. gordonii, but all C. albicans isolates develop robust biofilms with S. mutans irrespective of their filamentation state. Moreover, either type of C. albicans (hyphae defective or hyperfilamentous) enhances sucrose metabolism and biofilm acidogenicity, creating highly acidic environmental pH (<5.5). Notably, C. albicans isolates show altered transcriptomes associated with pH, adhesion, and cell wall composition (versus reference strains), further supporting niche-associated traits. Our data reveal that C. albicans displays distinctive adaptive mechanisms on the tooth surface and develops interactions with pathogenic bacteria while creating an acidogenic state regardless of fungal morphology, contrasting with interkingdom partnerships in mucosal infections. Human tooth may provide new insights into fungal colonization/adaptation, interkingdom biofilms, and contributions to disease pathogenesis. IMPORTANCE Severe early childhood caries is a widespread global public health problem causing extensive tooth decay and systemic complications. Candida albicans, a fungus typically found in mucosal surfaces, is frequently detected in dental plaque formed on teeth of diseased toddlers. However, the clinical traits of C. albicans isolated from tooth remain underexplored. Here, we find that C. albicans tooth isolates exhibit unique biological and transcriptomic traits. Notably, interkingdom biofilms with S. mutans can be formed irrespective of their filamentation state. Furthermore, tooth isolates commonly share dental caries-promoting functions, including acidogenesis, proteolytic activity, and enhanced sugar metabolism, while displaying increased expression of pH-responsive and adhesion genes. Our findings reveal that C. albicans colonizing human teeth displays distinctive adaptive mechanisms to mediate interkingdom interactions associated with a disease-causing state on a mineralized surface, providing new insights into Candida pathobiology and its role in a costly pediatric disease.

QCR7 affects the virulence of Candida albicans and the uptake of multiple carbon sources present in different host niches

Background

Candida albicans is a commensal yeast that may cause life-threatening infections. Studies have shown that the cytochrome b-c1 complex subunit 7 gene (QCR7) of C. albicans encodes a protein that forms a component of the mitochondrial electron transport chain complex III, making it an important target for studying the virulence of this yeast. However, to the best of our knowledge, the functions of QCR7 have not yet been characterized.

Methods

A QCR7 knockout strain was constructed using SN152, and BALb/c mice were used as model animals to determine the role of QCR7 in the virulence of C. albicans. Subsequently, the effects of QCR7 on mitochondrial functions and use of carbon sources were investigated. Next, its mutant biofilm formation and hyphal growth maintenance were compared with those of the wild type. Furthermore, the transcriptome of the qcr7Δ/Δ mutant was compared with that of the WT strain to explore pathogenic mechanisms.

Results

Defective QCR7 reduced recruitment of inflammatory cells and attenuated the virulence of C. albicans infection in vivo. Furthermore, the mutant influenced the use of multiple alternative carbon sources that exist in several host niches (GlcNAc, lactic acid, and amino acid, etc.). Moreover, it led to mitochondrial dysfunction. Furthermore, the QCR7 knockout strain showed defects in biofilm formation or the maintenance of filamentous growth. The overexpression of cell-surface-associated genes (HWP1, YWP1, XOG1, and SAP6) can restore defective virulence phenotypes and the carbon-source utilization of qcr7Δ/Δ.

Conclusion

This study provides new insights into the mitochondria-based metabolism of C. albicans, accounting for its virulence and the use of variable carbon sources that promote C. albicans to colonize host niches.

Effects of TiS2 on Inhibiting Candida albicans Biofilm Formation and Its Compatibility with Human Gingival Fibroblasts in Titanium Implants

Titanium is widely used in medical devices, such as dental and orthopedic implants, due to its excellent mechanical properties, low toxicity, and biocompatibility. However, the titanium surface has the risk of microbial biofilm formation, which results in infections from species such as Candida albicans (C. albicans). This kind of biofilm prevents antifungal therapy and complicates the treatment of infectious diseases associated with implanted devices. It is critical to developing a feasible surface to decrease microbial growth while not interfering with the growth of the host cells. This study reports the influence of titanium surface modification to titanium disulfide (TiS₂) on inhibiting C. albicans biofilm formation while allowing the attachment of human gingival fibroblasts (HGFs) on their surface. The surface of titanium parts is directly converted to structured titanium and TiS₂ using direct laser processing and crystal growth methods. C. albicans adhesion and colonization are then investigated on these surfaces by the colony counting assay and reactive oxygen species (ROS) assay, using 2',7'-dichlorofluorescin diacetate (DCFH-DA) and microscopy images. Also, the viability and adhesion of HGFs on these surfaces are investigated to show their adhesion and biocompatibility. Titanium samples with the TiS₂ surface show both C. albicans biofilm inhibition and HGF attachment. This study provides insight into designing and manufacturing titanium biomedical implants.

Inhibitory effect of lactobacilli supernatants on biofilm and filamentation of Candida albicans, Candida tropicalis, and Candida parapsilosis

Introduction

Probiotic Lactobacillus strains had been investigated for the potential to protect against infection caused by the major fungal pathogen of human, Candida albicans. Besides antifungal activity, lactobacilli demonstrated a promising inhibitory effect on biofilm formation and filamentation of C. albicans. On the other hand, two commonly isolated non-albicans Candida species, C. tropicalis and C. parapsilosis, have similar characteristics in filamentation and biofilm formation with C. albicans. However, there is scant information of the effect of lactobacilli on the two species.

Methods

In this study, biofilm inhibitory effects of L. rhamnosus ATCC 53103, L. plantarum ATCC 8014, and L. acidophilus ATCC 4356 were tested on the reference strain C. albicans SC5314 and six bloodstream isolated clinical strains, two each of C. albicans, C. tropicalis, and C. parapsilosis.

Results and Discussion

Cell-free culture supernatants (CFSs) of L. rhamnosus and L. plantarum significantly inhibited in vitro biofilm growth of C. albicans and C. tropicalis. L. acidophilus, conversely, had little effect on C. albicans and C. tropicalis but was more effective on inhibiting C. parapsilosis biofilms. Neutralized L. rhamnosus CFS at pH 7 retained the inhibitory effect, suggesting that exometabolites other than lactic acid produced by the Lactobacillus strain might be accounted for the effect. Furthermore, we evaluated the inhibitory effects of L. rhamnosus and L. plantarum CFSs on the filamentation of C. albicans and C. tropicalis strains. Significantly less Candida filaments were observed after co-incubating with CFSs under hyphae-inducing conditions. Expressions of six biofilm-related genes (ALS1, ALS3, BCR1, EFG1, TEC1, and UME6 in C. albicans and corresponding orthologs in C. tropicalis) in biofilms co-incubated with CFSs were analyzed using quantitative real-time PCR. When compared to untreated control, the expressions of ALS1, ALS3, EFG1, and TEC1 genes were downregulated in C. albicans biofilm. In C. tropicalis biofilms, ALS3 and UME6 were downregulated while TEC1 was upregulated. Taken together, the L. rhamnosus and L. plantarum strains demonstrated an inhibitory effect, which is likely mediated by the metabolites secreted into culture medium, on filamentation and biofilm formation of C. albicans and C. tropicalis. Our finding suggested an alternative to antifungals for controlling Candida biofilm.

Antifungal drug-resistance mechanisms in Candida biofilms

Infections caused by the Candida species of human fungal pathogens are a significant medical problem because they can disseminate to nearly every organ of the body. In addition, there are only a few classes of antifungal drugs available to treat patients with invasive fungal infections. Candida infections that are associated with biofilms can withstand much higher concentrations of antifungal drugs compared with infections caused by planktonic cells, thus making biofilm infections particularly challenging to treat. Candida albicans is among the most prevalent fungal species of the human microbiota, asymptomatically colonizing several niches of the body, including the gastrointestinal tract, genitourinary tract, mouth, and skin. Immunocompromised health conditions, dysbiosis of the microbiota, or environmental changes, however, can lead to C. albicans overgrowth, causing infections that range from superficial mucosal infections to severe hematogenously disseminated infections. Here, we review the current knowledge of antifungal drug-resistance mechanisms occurring in Candida biofilms.

Instantaneous Clearing of Biofilm (iCBiofilm): an optical approach to revisit bacterial and fungal biofilm imaging

Whole-biofilm imaging at single-cell resolution is necessary for system-level analysis of cellular heterogeneity, identification of key matrix component functions and response to immune cells and antimicrobials. To this end, we developed a whole-biofilm clearing and imaging method, termed instantaneous clearing of biofilm (iCBiofilm). iCBiofilm is a simple, rapid, and efficient method involving the immersion of biofilm samples in a refractive index-matching medium, enabling instant whole-biofilm imaging with confocal laser scanning microscopy. We also developed non-fixing iCBiofilm, enabling live and dynamic imaging of biofilm development and actions of antimicrobials. iCBiofilm is applicable for multicolor imaging of fluorescent proteins, immunostained matrix components, and fluorescence labeled cells in biofilms with a thickness of several hundred micrometers. iCBiofilm is scalable from bacterial to fungal biofilms and can be used to observe biofilm-neutrophil interactions. iCBiofilm therefore represents an important advance for examining the dynamics and functions of biofilms and revisiting bacterial and fungal biofilm formation.

Triazine-Based Small Molecules: A Potential New Class of Compounds in the Antifungal Toolbox

Invasive fungal infections caused by Candida species remain a significant public health problem worldwide. The increasing prevalence of drug-resistant infections and a limited arsenal of antifungal drugs underscore the need for novel interventions. Here, we screened several classes of pharmacologically active compounds against mammalian diseases for antifungal activity. We found that the synthetic triazine-based compound melanogenin (Mel) 56 is fungicidal in Candida albicans laboratory and clinical strains with minimal inhibitory concentrations of 8−16 µg/mL. Furthermore, Mel56 has general antifungal activity in several non-albicans Candida species and the non-pathogenic yeast Saccharomyces cerevisiae. Surprisingly, Mel56 inhibited the yeast-to-hyphae transition at sublethal concentrations, revealing a new role for triazine-based compounds in fungi. In human cancer cell lines, Mel56 targets the inner mitochondrial integral membrane prohibitin proteins, PHB1 and PHB2. However, Mel56 treatment did not impact C. albicans mitochondrial activity, and antifungal activity was similar in prohibitin single, double, and triple homozygous mutant strains compared to the wild-type parental strain. These results suggests that Mel56 has a novel mechanism-of-action in C. albicans. Therefore, Mel56 is a promising antifungal candidate warranting further analyses.

Metal Nanoparticles to Combat Candida albicans Infections: An Update

Candidiasis is an opportunistic mycosis with high annual incidence worldwide. In these infections, Candida albicans is the chief pathogen owing to its multiple virulence factors. C. albicans infections are usually treated with azoles, polyenes and echinocandins. However, these antifungals may have limitations regarding toxicity, relapse of infections, high cost, and emergence of antifungal resistance. Thus, the development of nanocarrier systems, such as metal nanoparticles, has been widely investigated. Metal nanoparticles are particulate dispersions or solid particles 10-100 nm in size, with unique physical and chemical properties that make them useful in biomedical applications. In this review, we focus on the activity of silver, gold, and iron nanoparticles against C. albicans. We discuss the use of metal nanoparticles as delivery vehicles for antifungal drugs or natural compounds to increase their biocompatibility and effectiveness. Promisingly, most of these nanoparticles exhibit potential antifungal activity through multi-target mechanisms in C. albicans cells and biofilms, which can minimize the emergence of antifungal resistance. The cytotoxicity of metal nanoparticles is a concern, and adjustments in synthesis approaches or coating techniques have been addressed to overcome these limitations, with great emphasis on green synthesis.

Asian Ancistrocladus Lianas as Creative Producers of Naphthylisoquinoline Alkaloids

This book describes a unique class of secondary metabolites, the mono- and dimeric naphthylisoquinoline alkaloids. They occur in lianas of the paleotropical Ancistrocladaceae and Dioncophyllaceae families, exclusively. Their unprecedented structures include stereogenic centers and rotationally hindered, and thus likewise stereogenic, axes. Extended recent investigations on six Ancistrocladus species from Asia, as reported in this review, shed light on their fascinating phytochemical productivity, with over 100 such intriguing natural products. This high chemodiversity arises from a likewise unique biosynthesis from acetate-malonate units, following a novel polyketidic pathway to plant-derived isoquinoline alkaloids. Some of the compounds show most promising antiparasitic activities. Likewise presented are strategies for the regio- and stereoselective total synthesis of the alkaloids, including the directed construction of the chiral axis.

Inhibitory effects of vaginal Lactobacilli on Candida albicans growth, hyphal formation, biofilm development, and epithelial cell adhesion

Introduction

Antifungal agents are not always efficient in resolving vulvovaginal candidiasis (VVC), a common genital infection caused by the overgrowth of Candida spp., including Candida albicans, or in preventing recurrent infections. Although lactobacilli (which are dominant microorganisms constituting healthy human vaginal microbiota) are important barriers against VVC, the Lactobacillus metabolite concentration needed to suppress VVC is unknown.

Methods

We quantitatively evaluated Lactobacillus metabolite concentrations to determine their effect on Candida spp., including 27 vaginal strains of Lactobacillus crispatus, L. jensenii, L. gasseri, Lacticaseibacillus rhamnosus, and Limosilactobacillus vaginalis, with inhibitory abilities against biofilms of C. albicans clinical isolates.

Results

Lactobacillus culture supernatants suppressed viable fungi by approximately 24%-92% relative to preformed C. albicans biofilms; however, their suppression differed among strains and not species. A moderate negative correlation was found between Lactobacillus lactate production and biofilm formation, but no correlation was observed between hydrogen peroxide production and biofilm formation. Both lactate and hydrogen peroxide were required to suppress C. albicans planktonic cell growth. Lactobacillus strains that significantly inhibited biofilm formation in culture supernatant also inhibited C. albicans adhesion to epithelial cells in an actual live bacterial adhesion competition test.

Discussion

Healthy human microflora and their metabolites may play important roles in the development of new antifungal agent against C. albicans-induced VVC.

Calcofluor white-cholesteryl hydrogen succinate conjugate mediated liposomes for enhanced targeted delivery of voriconazole into Candida albicans

A nano antifungal-drug delivery system is designed to increase voriconazole efficacy by specifically binding to chitin in the fungal cell wall.

Candida albicans-enteric viral interactions-The prostaglandin E2 connection and host immune responses

The human microbiome comprises trillions of microorganisms residing within different mucosal cavities and across the body surface. The gut microbiota modulates host susceptibility to viral infections in several ways, and microbial interkingdom interactions increase viral infectivity within the gut. Candida albicans, a frequently encountered fungal species in the gut, produces highly structured biofilms and eicosanoids such as prostaglandin E₂ (PGE₂), which aid in viral protection and replication. These biofilms encompass viruses and provide a shield from antiviral drugs or the immune system. PGE₂ is a key modulator of active inflammation with the potential to regulate interferon signaling upon microbial invasion or viral infections. In this review, we raise the perspective of gut interkingdom interactions involving C. albicans and enteric viruses, with a special focus on biofilms, PGE₂, and viral replication. Ultimately, we discuss the possible implications of C. albicans-enteric virus associations on host immune responses, particularly the interferon signaling pathway.

Hexyl-Aminolevulinate Ethosomes: a Novel Antibiofilm Agent Targeting Zinc Homeostasis in Candida albicans

Substantial drug resistance afforded by Candida albicans biofilms results in ineffective treatment with conventional drugs and persistent infection. Our previous study showed that hexyl-aminolevulinate ethosomes (HAL-ES) act against C. albicans biofilms and weaken their drug resistance and pathogenicity; however, the mechanism involved remains unclear. Here, we systematically evaluated the effects and mechanisms of HAL-ES on biofilm formation and drug resistance. We found that, in addition to mediating antifungal photodynamic therapy, HAL-ES inhibited the early, developmental, and mature stages of biofilm formation compared with fluconazole, HAL, or ES. Notably, adhesion and hyphal formation were significantly inhibited by postdrug effects even after brief exposure (2 h) to HAL-ES. Its therapeutic effect in vivo also has been demonstrated in cutaneous candidiasis. RNA sequencing and quantitative PCR showed that HAL-ES inhibited ribosome biogenesis by disrupting zinc homeostasis in C. albicans, thereby reducing the translation process during protein synthesis. Furthermore, HAL-ES downregulated the expression of multidrug resistance genes and increased fluconazole susceptibility in C. albicans. Our findings provide a novel and efficient method for the treatment of biofilm resistance in C. albicans infection as well as a basis for the application of HAL-ES. We also describe a new strategy for the treatment of biofilm-related infections via zinc restriction. IMPORTANCE Candida albicans is the most prevalent fungal species of the human microbiota. The medical impact of C. albicans on its human host depends on its ability to form biofilms. The intrinsic resistance conferred by biofilms to conventional antifungal drugs makes biofilm-based infections a significant clinical challenge. In this study, we demonstrate the attenuating effect of HAL-ES on C. albicans biofilm formation and drug resistance. Furthermore, we propose that HAL-ES inhibits protein translation by disrupting zinc homeostasis in C. albicans. This study not only provides a novel and effective therapeutic strategy against C. albicans biofilm but also proposes a new strategy to resolve C. albicans biofilm infection by disrupting zinc homeostasis.

Extracellular Vesicles Contribute to Mixed-Fungal Species Competition during Biofilm Initiation

Extracellular vesicles commonly modulate interactions among cellular communities. Recent studies demonstrate that biofilm maturation features, including matrix production, drug resistance, and dispersion, require the delivery of a core protein and carbohydrate vesicle cargo in Candida species. The function of the vesicle cargo for these advanced-phase biofilm characteristics appears to be conserved across Candida species. Mixed-species interactions in mature biofilms indicate that vesicle cargo serves a cooperative role in preserving the community. Here, we define the function of biofilm-associated vesicles for biofilm initiation both within and among five species across the Candida genus. We found similar vesicle cargo functions for several conserved proteins across species, based on the behavior of mutants. Repletion of the adhesion environment with wild-type vesicles returned the community phenotype toward reference levels in intraspecies experiments. However, cross-species vesicle complementation did not restore the wild-type biology and in fact drove the phenotype in the opposite direction for most cross-species interactions. Further study of mixed-species biofilm adhesion and exogenous wild-type vesicle administration similarly demonstrated competitive interactions. Our studies indicate that similar vesicle cargoes contribute to biofilm initiation. However, vesicles from disparate species serve an interference competitive role in mixed-Candida species scenarios. IMPORTANCE Candida species commonly form mixed-species biofilms with other Candida species and bacteria. In the established biofilm state, vesicle cargo delivers public goods to support the mature community. At biofilm initiation, however, vesicles play a negative role in cross-species interactions, presumably to allow species to gain a survival advantage. These observations and recent reports reveal that vesicle cargo has both cooperative and competitive roles among Candida species, depending on the needs of the community biofilm formation.

The Anti-Virulence Effect of Vismia guianensis against Candida albicans and Candida glabrata

In folk medicine, Vismia guianensis is used to treat skin diseases and mycoses in the Amazon region. We evaluated the anti-Candida activity of the hydroalcoholic extract from the leaves of Vismia guianensis (EHVG). HPLC-PDA and FIA-ESI-IT-MSⁿ were used to chemically characterize EHVG. The anti-Candida activity was determined in vitro by the minimum inhibitory concentrations (MIC) against Candida glabrata (ATCC-2001); Candida albicans (ATCC-90028, ATCC-14053, and ATCC-SC5314), and C. albicans clinical isolates. EHVG effects on adhesion, growth, and biofilm formation were also determined. Molecular docking was used to predict targets for EHVG compounds. The main compounds identified included anthraquinone, vismione D, kaempferol, quercetin, and vitexin. EHVG was fungicidal against all tested strains. C. albicans ATCC 14053 and C. glabrata ATCC 2001 were the most sensitive strains, as the extract inhibited their virulence factors. In silico analysis indicated that vismione D presented the best antifungal activity, since it was the most effective in inhibiting CaCYP51, and may act as anti-inflammatory and antioxidant agent, according to the online PASS prediction. Overall, the data demonstrate that EHVG has an anti-Candida effect by inhibiting virulence factors of the fungi. This activity may be related to its vismione D content, indicating this compound may represent a new perspective for treating diseases caused by Candida sp.

Correlation Between Drug Resistance and Virulence of Candida Isolates from Patients with Candidiasis

Purpose

This article aims to provide a theoretical basis for new or adjuvant strategies to facilitate the early diagnosis and treatment of candidiasis and to determine if drug-resistant Candida would affect virulence.

Patients and Methods

Our strains were collected from patients diagnosed with candidiasis in our hospital. The strains were identified by MALDI-TOF system and ITS sequencing. Antifungal sensitivity testing in vitro was performed to evaluate susceptibility of these isolates to current widely used antifungal drugs. The Galleria mellonella larvae model infected by Candida spp. was used to compare the virulence of drug-resistant and susceptible Candida spp.

Results

A total of 206 Candida strains were collected from clinical specimens. Candida albicans was the most common species among them, and was predominantly isolated from male patients aged over 40 years in ICU environments suffering from pulmonary and/or cerebral conditions. The accuracy rate of MALDI TOF-MS identification was 92.72% when compared with ITS sequencing as the standard method. Most Candida species, except for C. tropicalis which showed high resistance to micafungin, showed high susceptibilities to voriconazole, itraconazole, amphotericin B and micafungin but were highly resistant to terbinafine. For each specific Candida species, the G. mellonella larvae model revealed that the virulence of drug-resistant Candida isolates did not markedly differ from that of the drug-susceptible isolates, however, the virulence was dose-dependent on inoculated fungal cells in this model.

Conclusion

The possibility of Candida infection should not be neglected in patients at critical care hospital settings and C. albicans is the most common causative agent. MALDI-TOF MS has the advantages of rapidity and high accuracy, and should be a preferred method for identification of Candida spp. in a clinical laboratory. Voriconazole, itraconazole, amphotericin B and micafungin can still be recommended as the first line antifungals to treat candidiasis.

Visualized Gallium/Lyticase-Integrated Antifungal Strategy for Fungal Keratitis Treatment

Fungal keratitis has been one of the common corneal infections that causes blindness, but an effective antifungal strategy remains a challenge. The exopolysaccharides both in the fungal cell walls and biofilms are a key that acts as a permeation barrier to weaken the therapeutic effect of antifungal agents. Herein, lyticase and gallium ions co-integrated nanosystems (MLPGa) are presented that can degrade exopolysaccharides and then effectively eradicate both planktonic Candida albicans and mature biofilms. The potential antifungal mechanism involves reactive oxygen species (ROS) production and metabolic interference of antioxidant-related genes, exopolysaccharide-related genes, iron-ion-utilization-related genes, fungal/biofilm-development-related genes, and virulence genes. Meanwhile, the Raman signals generated by the chelation between the nanosystems and the gallium ions provide a real-time visualization tool to monitor Ga release. Finally, the MLPGa-based antifungal strategy with good biocompatibility achieves a satisfactory therapeutic effect in a fungal keratitis mouse model. This study provides a unique approach to the effective treatment of fungal keratitis in clinical practice.

The Bovhyaluronidase Azoximer (Longidaza®) Disrupts Candida albicans and Candida albicans-Bacterial Mixed Biofilms and Increases the Efficacy of Antifungals

Background and Objectives: Candida albicans causes various diseases ranging from superficial mycoses to life-threatening systemic infections often associated with biofilm formation, including mixed fungal−bacterial consortia. The biofilm matrix protects cells, making Candida extremely resistant to treatment. Here, we show that the bovhyaluronidase azoximer (Longidaza®) in vitro destroys the biofilm formed by either C. albicans alone or mixed with bacteria, this way decreasing the concentrations of antimicrobials required for the pathogen’s eradication. Materials and Methods: Bovhyaluronidase azoximer, Longidaza® was obtained from NPO Petrovax Pharm Ltd., Moscow, Russia as lyophilized powder. The antifungal activity was assessed by microdilution assay and CFUs counting. Antibiofilm activity was evaluated via biofilms staining and scanning electron microscopy. Results: Thus, treatment with Longidaza® reduced the biofilm biomass of nine C. albicans clinical isolates by 30−60%, while mixed biofilms of C. albicans with various bacteria were destroyed by 30−40%. Furthermore, the concentration of fluconazole required to achieve a similar reduction of the residual respiratory activity of detached cell clumps of four C. albicans isolates has been reduced four-fold when combined with Longidaza®. While in the biofilm, two of four isolates became significantly more susceptible to fluconazole in combination with Longidaza®. Conclusion: Taken together, our data indicate that Longidaza® is capable of suppression of tissues and artificial surfaces biofouling by C. albicans biofilms, as well as facilitating drug penetration into the cell clumps, this way decreasing the effective MIC of antifungals.

Capsules with bacteria and fungi in distinct compartments: A platform for studying microbes from different kingdoms and their cross-communication

Recently, we have created ‘artificial cells’ with an architecture mimicking that of typical eukaryotic cells. Our design uses common biopolymers like alginate and chitosan to create multi-compartment capsules (MCCs) via oil-free microfluidics. MCCs (~ 500 μm in diameter) can be engineered with multiple inner compartments, each with a distinct payload. This mimics the distinct organelles in eukaryotic cells, each of which has unique properties. In this study, we encapsulate microbial cells from two distinct kingdoms — Pseudomonas aeruginosa (bacteria) and Candida albicans (fungi) — in the inner compartments of MCCs. The two microbes are commonly found in biofilms at sites of infection in humans. We first demonstrate that the MCC can serve as a simple platform to observe the comparative growth of the cells in real time. Unlike typical co-culture in solution or on agar plates, the cells can grow in their own compartments without direct physical contact. Moreover, the hydrogel matrix in the compartments mimics the three-dimensional (3-D) environment that cells naturally encounter during their growth. Small molecules added to the solution are shown to permeate through the capsule walls and affect cell growth: for example, cationic surfactants inhibit the fungi but not the bacteria. Conversely, low pH and kanamycin inhibit the bacteria but not the fungi. Also, when the bacteria are present in adjacent compartments, the fungal cells mostly stay in a yeast morphology, meaning as spheroidal cells. In contrast, in the absence of the bacteria, the fungi transition into hyphae, i.e., long multicellular filaments. The inhibition of this morphological switch in fungal cells is shown to be induced by signaling molecules (specifically, the quorum sensing autoinducer-1 or AI-1) secreted by the bacteria. Thus, the MCC platform can also be used to detect cross-kingdom signaling between the compartmentalized microbes.

Cross-kingdom interaction between Candida albicans and oral bacteria

Candida albicans is a symbiotic fungus that commonly colonizes on oral mucosal surfaces and mainly affects immuno-compromised individuals. Polymicrobial interactions between C. albicans and oral microbes influence the cellular and biochemical composition of the biofilm, contributing to change clinically relevant outcomes of biofilm-related oral diseases, such as pathogenesis, virulence, and drug-resistance. Notably, the symbiotic relationships between C. albicans and oral bacteria have been well-documented in dental caries, oral mucositis, endodontic and periodontal diseases, implant-related infections, and oral cancer. C. albicans interacts with co-existing oral bacteria through physical attachment, extracellular signals, and metabolic cross-feeding. This review discusses the bacterial-fungal interactions between C. albicans and different oral bacteria, with a particular focus on the underlying mechanism and its relevance to the development and clinical management of oral diseases.

Menthol Inhibits Candida albicans Growth by Affecting the Membrane Integrity Followed by Apoptosis

Inclusion of Candida albicans in the list of pathogens with potential drug resistance threat in recent years has compelled scientists to explore novel and potent antifungal agents. In this study, we have evaluated anti-Candida potential of menthol against different growth forms and synergistic potential with fluconazole. Menthol inhibited planktonic growth of all the isolates completely at ≤3.58 mM and killed 99.9% inoculum at MIC, indicating that menthol is fungicidal. Menthol inhibited hyphal form growth completely at 0.62 mM. It has inhibited developing a biofilm by 79% at 3.58 mM, exhibiting excellent activity against recalcitrant biofilms. FIC index values of 0.182 and 0.093 indicate excellent synergistic activity between fluconazole and menthol against planktonic and biofilm growth, respectively. Menthol enhanced rate of OxPhos among 22% cells; arrested 71% cells at G2-M phase of cell cycle and induced apoptosis in 15% cells. Thus, menthol exhibits excellent anti-Candida activity against differentially susceptible isolates as well as various growth and morphological forms of C. albicans. Menthol affects membrane integrity thereby inducing oxidative stress followed by cell cycle arrest and apoptosis. Considering the excellent anti-Candida potential and as it is Generally Recognized as Safe by the Food and Drug Administration, it may find use in antifungal chemotherapy, alone or in combination.

Effects of Hst3p inhibition in Candida albicans: a genome-wide H3K56 acetylation analysis

Candida spp. represent the third most frequent worldwide cause of infection in Intensive Care Units with a mortality rate of almost 40%. The classes of antifungals currently available include azoles, polyenes, echinocandins, pyrimidine derivatives, and allylamines. However, the therapeutical options for the treatment of candidiasis are drastically reduced by the increasing antifungal resistance. The growing need for a more targeted antifungal therapy is limited by the concern of finding molecules that specifically recognize the microbial cell without damaging the host. Epigenetic writers and erasers have emerged as promising targets in different contexts, including the treatment of fungal infections. In C. albicans, Hst3p, a sirtuin that deacetylates H3K56ac, represents an attractive antifungal target as it is essential for the fungus viability and virulence. Although the relevance of such epigenetic regulator is documented for the development of new antifungal therapies, the molecular mechanism behind Hst3p-mediated epigenetic regulation remains unrevealed. Here, we provide the first genome-wide profiling of H3K56ac in C. albicans resulting in H3K56ac enriched regions associated with Candida sp. pathogenicity. Upon Hst3p inhibition, 447 regions gain H3K56ac. Importantly, these genomic areas contain genes encoding for adhesin proteins, degradative enzymes, and white-opaque switching. Moreover, our RNA-seq analysis revealed 1330 upregulated and 1081 downregulated transcripts upon Hst3p inhibition, and among them, we identified 87 genes whose transcriptional increase well correlates with the enrichment of H3K56 acetylation on their promoters, including some well-known regulators of phenotypic switching and virulence. Based on our evidence, Hst3p is an appealing target for the development of new potential antifungal drugs.

The Antimicrobial Peptide AMP-17 Derived from Musca domestica Inhibits Biofilm Formation and Eradicates Mature Biofilm in Candida albicans

The biofilm formation of C. albicans represents a major virulence factor during candidiasis. Biofilm-mediated drug resistance has necessitated the search for a new antifungal treatment strategy. In our previous study, a novel antimicrobial peptide named AMP-17 derived from Musca domestica was confirmed to have significant antifungal activity and suppress hyphal growth greatly in C. albicans. In the current work, we aimed to investigate the antibiofilm property of AMP-17 in C. albicans and explore the underlying mechanism. An antifungal susceptibility assay showed that AMP-17 exerted a strong inhibitory efficacy on both biofilm formation and preformed biofilms in C. albicans. Furthermore, AMP-17 was found to block the yeast-to-hypha transition and inhibit the adhesion of biofilm cells with a reduction in cellular surface hydrophobicity. A morphological analysis revealed that AMP-17 indeed suppressed typical biofilm formation and damaged the structures of the preformed biofilm. The RNA-seq showed that the MAPK pathway, biosynthesis of antibiotics, and essential components of the cell were mainly enriched in the biofilm-forming stage, while the citrate cycle (TCA cycle), phenylamine metabolism, and propanoate metabolism were enriched after the biofilm matured. Moreover, the co-expressed DEGs in the two pairwise comparisons highlighted the terms of transmembrane transporter activity, regulation of filamentation, and biofilm formation as important roles in the antibiofilm effect of AMP-17. Additionally, qRT-PCR confirmed that the level of the genes involved in cell adhesion, filamentous growth, MAPK, biofilm matrix, and cell dispersal was correspondingly altered after AMP-17 treatment. Overall, our findings reveal the underlying antibiofilm mechanisms of AMPs in C. albicans, providing an interesting perspective for the development of effective antifungal agents with antibiofilm efficacy in Candida spp.

Anti-Candida albicans Activity of Ononin and Other Secondary Metabolites from Platonia Insignis MART

Candida albicans is a human pathogen that is part of the healthy microbiome. However, it is often associated with opportunistic fungal infections. The treatment of these infections is challenging because prolonged exposure to antifungal drugs can culminate in fungal resistance during therapy, and there is a limited number of available drugs. Therefore, this study investigated the antifungal activity of ononin by in silico and in vitro assays, and in Tenebrio molitor as an alternative in vivo model of infection caused by C. albicans. Ononin is an isoflavone glycoside derived from formononetin that has various biological activities. According in silico evaluation, ononin showed the best electron affinity in molecular docking with CaCYP51, with a binding free energy of -10.89 kcal/mol, superior to that of the antifungal drugs fluconazole and posaconazole. The ononin + CaCYP51 complex formed hydrogen bonds with Tyr132, Ser378, Phe380, and Met508, as well as hydrophobic connections with Tyr118, Leu121, Phe126, Leu131, Ile304, and Leu309, and interactions with the heme group. Ononin exerted anti-Candida albicans activity, with MIC between 3.9 and 7.8 µg/mL, and inhibited young and mature biofilms, with a reduction in cell density and metabolic activity of 50 to 80%. The compound was not cytotoxic to sheep red blood cells at concentrations up to 1000 µg/mL. Larvae of the mealworm T. molitor were used as an alternative in vivo model of C. albicans infection. Ononin was able to prolong larval survival at concentrations of 0.5, 1, and 5 mg/kg, and was not toxic up to a concentration of 20 mg/kg. Moreover, ononin reduced the fungal charge in treated animals. In conclusion, our results suggest that ononin has anti-Candida albicans activity and is a potential candidate for the development of new therapeutic alternatives.

Filamentous fungal biofilms: Conserved and unique aspects of extracellular matrix composition, mechanisms of drug resistance and regulatory networks in Aspergillus fumigatus

The filamentous fungus Aspergillus fumigatus is an ubiquitous mold that can cause invasive pulmonary infections in immunocompromised patients. Within the lung, A. fumigatus forms biofilms that can enhance resistance to antifungals and immune defenses, highlighting the importance of defining the mechanisms underlying biofilm development and associated emergent properties. A. fumigatus biofilms display a morphology and architecture that is distinct from bacterial and yeast biofilms. Moreover, A. fumigatus biofilms display unique characteristics in the composition of their extracellular matrix (ECM) and the regulatory networks governing biofilm formation. This review will discuss our current understanding of the form and function of A. fumigatus biofilms, including the unique components of ECM matrix, potential drug resistance mechanisms, the regulatory networks governing A. fumigatus biofilm formation, and potential therapeutics targeting these structures.

Interkingdom assemblages in human saliva display group-level surface mobility and disease-promoting emergent functions

Fungi and bacteria form multicellular biofilms causing many human infections. How such distinctive microbes act in concert spatiotemporally to coordinate disease-promoting functionality remains understudied. Using multiscale real-time microscopy and computational analysis, we investigate the dynamics of fungal and bacterial interactions in human saliva and their biofilm development on tooth surfaces. We discovered structured interkingdom assemblages displaying emergent functionalities to enhance collective surface colonization, survival, and growth. Further analyses revealed an unexpected group-level surface mobility with coordinated “leaping-like” and “walking-like” motions while continuously growing. These mobile groups of growing cells promote rapid spatial spreading of both species across surfaces, causing more extensive tooth decay. Our findings show multicellular interkingdom assemblages acting like supraorganisms with functionalities that cannot be achieved without coassembly.

Fungi and bacteria often engage in complex interactions, such as the formation of multicellular biofilms within the human body. Knowledge about how interkingdom biofilms initiate and coalesce into higher-level communities and which functions the different species carry out during biofilm formation remain limited. We found native-state assemblages of Candida albicans (fungi) and Streptococcus mutans (bacteria) with highly structured arrangement in saliva from diseased patients with childhood tooth decay. Further analyses revealed that bacterial clusters are attached within a network of fungal yeasts, hyphae, and exopolysaccharides, which bind to surfaces as a preassembled cell group. The interkingdom assemblages exhibit emergent functions, including enhanced surface colonization and growth rate, stronger tolerance to antimicrobials, and improved shear resistance, compared to either species alone. Notably, we discovered that the interkingdom assemblages display a unique form of migratory spatial mobility that enables fast spreading of biofilms across surfaces and causes enhanced, more extensive tooth decay. Using mutants, selective inactivation of species, and selective matrix removal, we demonstrate that the enhanced stress resistance and surface mobility arise from the exopolymeric matrix and require the presence of both species in the assemblage. The mobility is directed by fungal filamentation as hyphae extend and contact the surface, lifting the assemblage with a “forward-leaping motion.” Bacterial cell clusters can “hitchhike” on this mobile unit while continuously growing, to spread across the surface three-dimensionally and merge with other assemblages, promoting community expansion. Together, our results reveal an interkingdom assemblage in human saliva that behaves like a supraorganism, with disease-causing emergent functionalities that cannot be achieved without coassembly.

Identification and functional characterization of ORF19.5274, a novel gene involved in both azoles susceptibility and hypha development in Candida albicans

Azole resistance is becoming increasingly serious due to the frequent recurrence of fungal infections and the need for long-term clinical prevention. In our previous study, we discovered ORF19.5274 with an unknown function by TMT^™ quantitative proteomics technology after fluconazole (FLC) treatment of Candida albicans. In this study, we created the target gene deletion strain using CRISPR-Cas9 editing technology to see if ORF19.5274 regulates azole sensitivity. The data showed that ORF19.5274 was involved in hyphal development and susceptibility to antifungal azoles. Deleting this gene resulted in defective hyphal growth in solid medium, while only a weak lag in the initiation of hyphal development and restoring hyphal growth during the hyphal maintenance phase under liquid conditions. Moreover, intracellular reactive oxygen species (ROS) assay and propidium iodide staining assays showed increased endogenous ROS levels and membrane permeability, but decreased metabolic activity of biofilm in orf19.5274Δ/Δ after treatment with FLC in comparison with either SC5314 or orf19.5274Δ/Δ::ORF19.5274 strains. More importantly, orf19.5274Δ/Δ significantly enhanced the FLC efficacy against C. albicans in infected Galleria mellonella larvae. The above characteristics were fully or partially restored in the complemented strain indicating that the changes caused by ORF19.5274 deletion were specific. In summary, the ORF19.5274 gene is required for hyphal development of C. albicans, and is correlated with the response to antifungal azoles in vitro and in vivo. The identification of ORF19.5275 is promising to expand the potential candidate targets for azoles.

The research progress in the interaction between Candida albicans and cancers

Candida albicans is an opportunistic pathogenic fungus, which tends to infect the host with defective immune function including cancer patients. A growing number of studies have shown that C. albicans infection increases the host susceptibility to cancer such as oral, gastric, and colorectal cancer. Cancer and anti-cancer treatment may also affect the colonization of C. albicans. C. albicans may promote the development of cancer by damaging mucosal epithelium, inducing the production of carcinogens, triggering chronic inflammation including Th17 cell-mediated immune response. In this article, we aim to elaborate the interaction between C. albicans and cancers development and summarize the potential molecular mechanisms, so as to provide theoretical basis for prevention, diagnosis and treatment of cancers.

A common vesicle proteome drives fungal biofilm development

Candida species are commensal organisms commonly interacting in the same host niche. In the pathogenic state, they frequently grow as a biofilm, often in mixed infections. The present studies observe a reliance upon common extracellular vesicle cargo for biofilm structure and function supporting interactions among species. The results reveal a vesicle cargo-driven coordination among Candida species during biofilm formation.

Extracellular vesicles mediate community interactions among cells ranging from unicellular microbes to complex vertebrates. Extracellular vesicles of the fungal pathogen Candida albicans are vital for biofilm communities to produce matrix, which confers environmental protection and modulates community dispersion. Infections are increasingly due to diverse Candida species, such as the emerging pathogen Candida auris, as well as mixed Candida communities. Here, we define the composition and function of biofilm-associated vesicles among five species across the Candida genus. We find similarities in vesicle size and release over the biofilm lifespan. Whereas overall cargo proteomes differ dramatically among species, a group of 36 common proteins is enriched for orthologs of C. albicans biofilm mediators. To understand the function of this set of proteins, we asked whether mutants in select components were important for key biofilm processes, including drug tolerance and dispersion. We found that the majority of these cargo components impact one or both biofilm processes across all five species. Exogenous delivery of wild-type vesicle cargo returned mutant phenotypes toward wild type. To assess the impact of vesicle cargo on interspecies interactions, we performed cross-species vesicle addition and observed functional complementation for both biofilm phenotypes. We explored the biologic relevance of this cross-species biofilm interaction in mixed species and mutant studies examining the drug-resistance phenotype. We found a majority of biofilm interactions among species restored the community’s wild-type behavior. Our studies indicate that vesicles influence the development of protective monomicrobial and mixed microbial biofilm communities.

Characterization of Cervus timorensis Velvet Antler and its Effect on Biofilm Formation of Candida Species

Oral biofilms comprise extracellular polysaccharides and polymicrobial microorganisms. The objectives of the study were to characterize the deer velvet antler (DVA) compounds and their effect on Candida species biofilm formation with the hypothesis that DVA inhibits the biofilm of Candida spp. Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry (LC-QTOF-MS) was conducted to characterize the DVA compounds. To study the effect of DVA on biofilm, Candida albicans ATCC MYA-4901 (ALT5), AIDS isolate (ALC2), oral cancer isolate (ALC3), C. dubliniensis ATCC MYA-2975, C. glabrata ATCC 90030, C. krusei 14 243, C. lusitaniae ATCC 34449, C. parapsilosis ATCC 22019, and C. tropicalis ATCC 13803 were inoculated with DVA in separate wells of a 96-well plate containing RPMI-1640 followed by 72 h incubation. A total of 45 compounds were detected in the DVA extract. C. lusitaniae exhibited a higher percentage of biofilm biomass reduction when treated with DVA extract (66.10% ± 5.33), followed by ALC3 (44.12% ± 6.24). However, C. glabrata, C. krusei, and C. parapsilosis showed no reduction in biofilm biomass after being treated with DVA extract. Most Candida strains also exhibited decreased total cell count when treated with DVA extract, except for ALC3 and C. krusei. ALT5 had the lowest total cell count (0.17 × 105 cells/mL) when cultured with DVA extract. In conclusion, DVA extract inhibits Candida spp. biofilm formation except for C. glabrata, C. krusei, and C. parapsilosis.

Network Analysis Guided Designing of Multi-Targeted Anti-Fungal Agents: Synthesis and Biological Evaluation

During the ongoing pandemic, there have been increasing reports of invasive fungal disease (IFD), particularly among immunocompromised populations. Candida albicans is one of the most common clinical pathogenic microorganisms which have become a serious health threat to population either infected with Covid-19 or on treatment with immunosuppressant's/broad-range antibiotics. Currently, benzothiazole is a well explored scaffold for anti-fungal activity, especially mercapto substituted benzothiazoles. It is reported that exploring the 2nd position of benzothiazoles yield improved anti-fungal molecules. Therefore, in the current study, lead optimization approach using bioisosteric replacement protocol was followed to improve the anti-fungal activity of an already reported benzothiazole derivative, N-(1,3-benzothiazole-2-yl)-2-(pyridine-3-ylformohydrazido) acetamide. To rationally identify the putative anti-candida targets of this derivative, network analysis was carried out. Complexes of designed compounds and identified putative targets were further analyzed for the docking interactions and their consequent retention after the completion of exhaustive MD simulations. Top seven designed compounds were synthesized and evaluated for in-vitro anti-fungal property against Candida, which indicated that compounds 1.2c and 1.2f possess improved and comparable anti-fungal activity to N-(1,3-benzothiazole-2-yl)-2-(pyridine-3-ylformohydrazido) acetamide and Nystatin, respectively.

Tachyplesin I Analogue Peptide as an Effective Antimicrobial Agent against Candida albicans-Staphylococcus aureus Poly-Biofilm Formation and Mixed Infection

Microbial biofilms are difficult to tackle in many infectious diseases. Candida albicans and Staphylococcus aureus are prevalent symbiotic strains in polymicrobial biofilms, which showed enhanced antimicrobial resistance and made identifying effective treatment techniques more difficult. The antibiofilm abilities of tachplesin I analogue peptide (TP11A) and tachplesin I were investigated quantitatively in this study. Both inhibited C. albicans monomicrobial, S. aureus monomicrobial, and C. albicans-S. aureus polymicrobial biofilms quite well. TP11A suppressed the biofilm- and virulence-related genes of C. albicans (hwp 1) and S. aureus (ica A, fnb B, agr A, hla, nor A, and sig B) in the mixed biofilm, according to quantitative reverse transcription polymerase chain reaction analysis. We created an injectable thermosensitive in situ PLEL@TP11A gel system by simply adding TP11A into poly(d,l-lactide)-poly(ethylene glycol)-poly(d,l-lactide) (PLEL). Using C. albicans-S. aureus mixed infected wound models of mice, the in vivo therapeutic effect of TP11A and PLEL@TP11A in polymicrobial infections was investigated. The findings revealed that TP11A and PLEL@TP11A could efficiently reduce bacterial and fungal burden in wound infections, as well as accelerated wound healing. Based on above findings, TP11A might be an effective antimicrobial against C. albicans-S. aureus poly-biofilm formation and mixed infection.

Biofilm Alterations on the Stepwise Acquisition of Fluconazole-resistant Candida Albicans Isolates

By assessing and comparing the phenotypic changes on the stepwise acquisition of fluconazole resistant Candida albicans isolates, we could find and describe the relationship between drug resistance and biofilm formation ability in a series of clonal strains.

Development and research progress of anti-drug resistant fungal drugs

With the widespread use of immunosuppressive agents and the increase in patients with severe infections, the incidence of fungal infections worldwide has increased year by year. The fungal pathogens Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus cause a total of more than 1 million deaths each year. Long-term use of antifungal drugs can easily lead to fungal resistance, and the prevalence of drug-resistant fungi is a major global health challenge. In order to effectively control global fungal infections, there is an urgent need for new drugs that can exert effective antifungal activity and overcome drug resistance. We must promote the discovery of new antifungal targets and drugs, and find effective ways to control drug-resistant fungi through different ways, so as to reduce the threat of drug-resistant fungi to human life, health and safety. In the past few years, certain progress has been made in the research and development of antifungal drugs. In addition to summarizing some of the antifungal drugs currently approved by the FDA, this review also focuses on potential antifungal drugs, the repositioned drugs, and drugs that can treat drug-resistant bacteria and fungal infections, and provide new ideas for the development of antifungal drugs in the future.

Mixed Fungal Biofilms: From Mycobiota to Devices, a New Challenge on Clinical Practice

Most current protocols for the diagnosis of fungal infections are based on culture-dependent methods that allow the evaluation of fungal morphology and the identification of the etiologic agent of mycosis. Most current protocols for the diagnosis of fungal infections are based on culture-dependent methods that enable the examination of the fungi for further identification of the etiological agent of the mycosis. The isolation of fungi from pure cultures is typically recommended, as when more than one species is identified, the second agent is considered a contaminant. Fungi mostly survive in highly organized communities that provoke changes in phenotypic profile, increase resistance to antifungals and environmental stresses, and facilitate evasion from the immune system. Mixed fungal biofilms (MFB) harbor more than one fungal species, wherein exchange can occur that potentialize the effects of these virulence factors. However, little is known about MFB and their role in infectious processes, particularly in terms of how each species may synergistically contribute to the pathogenesis. Here, we review fungi present in MFB that are commensals of the human body, forming the mycobiota, and how their participation in MFB affects the maintenance of homeostasis. In addition, we discuss how MFB are formed on both biotic and abiotic surfaces, thus being a significant reservoir of microorganisms that have already been associated in infectious processes of high morbidity and mortality.