Albicans Strains Research Articles

The microbial ecology of Candida albicans strains CHN1 and SC5314 in mice

Strain SC5314 is the most widely studied strain of Candida albicans. Despite C. albicans being the most commonly isolated yeast from the human gastrointestinal (GI) microbiome, strain SC5314 does not stably colonize the mouse GI tract long term, even after antibiotic disruption. In contrast, strain CHN1 will stably colonize the mouse GI tract long term. Comparative genomic analysis of strain CHN1 indicates that it belongs to a different evolutionary clade of C. albicans than strain SC5314. Previous studies from our laboratory have shown that colonization by strain CHN1 causes a change in the GI bacterial microbiome of mice and predisposes them to more robust Th2 immune responses. Despite this, little is known about the GI microbial ecology of SC5314 vs. CHN1 and subsequent host responses. Using a short-term antibiotic disruption model in C57BL/6 mice, we have been able to observe significantly different colonization kinetics between these two C. albicans strains, with CHN1 establishing stable long-term colonization. In contrast, colonization by SC5314 was lower, highly variable and cage-dependent. C. albicans colonization kinetics impacted the composition of the bacterial microbiome with a marked effect on the levels of Lactobacillus and Enterococcus. qPCR analysis of 46 host immune response genes did not detect significant differences in host gene expression between SC5134 and CHN1 colonized mice, except for chitinase expression. Thus, these studies suggest that yeast-bacteria interactions in the microbiome may be far more important in determining long-term colonization potential of C. albicans and secondary immunomodulatory effects.

A novel CRISPRi platform to study the role of essential genes in antifungal drug-resistant Candida albicans isolates

With the emergence of antifungal resistant Candida albicans strains, the need for new antifungal drugs is critical in combating this fungal pathogen. Investigating essential genes in C. albicans is a vital step in characterizing putative antifungal drug targets. As some of these essential genes are conserved between fungal organisms, developed therapies targeting these genes have the potential to be broad range antifungals. In order to study these essential genes, classical genetic knockout or CRISPR-based approaches cannot be used as disrupting essential genes leads to lethality in the organism. Fortunately, a variation of the CRISPR system (CRISPR interference or CRISPRi) exists that enables precise transcriptional repression of the gene of interest without introducing genetic mutations. CRISPRi utilizes an endonuclease dead Cas9 protein that can be targeted to a precise location but lacks the ability to create a double-stranded break. The binding of the dCas9 protein to DNA prevents the binding of RNA polymerase to the promoter through steric hindrance thereby reducing expression. We recently published the novel use of this technology in C. albicans and are currently working on expanding this technology to large scale repression of essential genes. Through the construction of an essential gene CRISPRi-sgRNA library, we can begin to study the function of essential genes under different conditions and identify genes that are involved in critical processes such as drug tolerance in antifungal resistant background strains. These genes can ultimately be characterized as putative targets for novel antifungal drug development, or targeted as a means to sensitize drug-resistant strains to antifungal treatment.

Proteogenomics analysis of CUG codon translation in the human pathogen Candida albicans

BackgroundYeasts of the CTG-clade lineage, which includes the human-infecting Candida albicans, Candida parapsilosis and Candida tropicalis species, are characterized by an altered genetic code. Instead of translating CUG codons as leucine, as happens in most eukaryotes, these yeasts, whose ancestors are thought to have lost the relevant leucine-tRNA gene, translate CUG codons as serine using a serine-tRNA with a mutated anticodon, {mathrm{tRNA}}_{mathrm{CAG}}^{mathrm{Ser}} . Previously reported experiments have suggested that 3–5% of the CTG-clade CUG codons are mistranslated as leucine due to mischarging of the {mathrm{tRNA}}_{mathrm{CAG}}^{mathrm{Ser}} . The mistranslation was suggested to result in variable surface proteins explaining fast host adaptation and pathogenicity.ResultsIn this study, we reassess this potential mistranslation by high-resolution mass spectrometry-based proteogenomics of multiple CTG-clade yeasts, including various C. albicans strains, isolated from colonized and from infected human body sites, and C. albicans grown in yeast and hyphal forms. Our data do not support a bias towards CUG codon mistranslation as leucine. Instead, our data suggest that (i) CUG codons are mistranslated at a frequency corresponding to the normal extent of ribosomal mistranslation with no preference for specific amino acids, (ii) CUG codons are as unambiguous (or ambiguous) as the related CUU leucine and UCC serine codons, (iii) tRNA anticodon loop variation across the CTG-clade yeasts does not result in any difference of the mistranslation level, and (iv) CUG codon unambiguity is independent of C. albicans’ strain pathogenicity or growth form.ConclusionsOur findings imply that C. albicans does not decode CUG ambiguously. This suggests that the proposed misleucylation of the {mathrm{tRNA}}_{mathrm{CAG}}^{mathrm{Ser}} might be as prevalent as every other misacylation or mistranslation event and, if at all, be just one of many reasons causing phenotypic diversity.

Kefir 유래 유산균 Lactobacillus pentosus Strains의 항균 및 항산화 효과

In this study, useful lactic acid bacteria were isolated from kefir, which contains complexes of bacteria, yeast and serves as a reservoir for beneficial strains. As a result of 16s rRNA sequence analysis of 2 strains of kefir-derived lactic acid bacteria with remarkable antimicrobial activity, both BMSE-K006 and K009 showed 99.86% homology with Lactobacillus pentosus DSM 20314. The availability of carbohydrate fermentation patterns of L. pentosus BMSE-K006 and K009 were similar, and the availability of D-galactose and lactose was observed, confirming the availability of sugar in milk or dairy products. Also the antimicrobial activity of L. pentosus BMSE-K006 and K009 showed the highest against pathogenic bacteria such as Staphylococcus spp., Escherichia spp., Pseudomonas aeruginosa, but no antifungal effect was observed against Candida albicans strains. L. pentosus BMSE-K006 and K009 cultured supernatant showed DPPH radical scavenging activity of 69.02% and 65.88%, respectively. Therefore, these results are expected that L. pentosus BMSE-K006 and K009 could be potential resources as useful lactic acid bacteria isolated from kefir.

Gut-Evolved Candida albicans Induces Metabolic Changes in Neutrophils.

Serial passaging of the human fungal pathogen Candida albicans in the gastrointestinal tract of antibiotics-treated mice selects for virulence-attenuated strains. These gut-evolved strains protect the host from infection by a wide range of pathogens via trained immunity. Here, we further investigated the molecular and cellular mechanisms underlying this innate immune memory. Both Dectin-1 (the main receptor for β-glucan; a well-described immune training molecule in the fungal cell wall) and Nod2 (a receptor described to mediate BCG-induced trained immunity), were redundant for the protection induced by gut-evolved C. albicans against a virulent C. albicans strain, suggesting that gut-evolved C. albicans strains induce trained immunity via other pathways. Cytometry by time of flight (CyTOF) analysis of mouse splenocytes revealed that immunization with gut-evolved C. albicans resulted in an expansion of neutrophils and a reduction in natural killer (NK) cells, but no significant numeric changes in monocytes, macrophages or dendritic cell populations. Systemic depletion of phagocytes or neutrophils, but not of macrophages or NK cells, reduced protection mediated by gut-evolved C. albicans. Splenocytes and bone marrow cells of mice immunized with gut-evolved C. albicans demonstrated metabolic changes. In particular, splenic neutrophils displayed significantly elevated glycolytic and respiratory activity in comparison to those from mock-immunized mice. Although further investigation is required for fully deciphering the trained immunity mechanism induced by gut-evolved C. albicans strains, this data is consistent with the existence of several mechanisms of trained immunity, triggered by different training stimuli and involving different immune molecules and cell types.

Polydopamine-Assisted Surface Modification of Ti-6Al-4V Alloy with Anti-Biofilm Activity for Dental Implantology Applications

Coating the surfaces of implantable materials with various active principles to ensure inhibition of microbial adhesion, is a solution to reduce infections associated with dental implant. The aim of the study was to optimize the polydopamine films coating on the Ti-6Al-6V alloy surface in order to obtain a maximum of antimicrobial/antibiofilm efficacy and reduced cytotoxicity. Surface characterization was performed by evaluating the morphology (SEM, AFM) and structures (Solid-state 13C NMR and EPR). Antimicrobial activity was assessed by logarithmic reduction of CFU/mL, and the antibiofilm activity by reducing the adhesion of Escherichia coli, Staphylococcus aureus, and Candida albicans strains. The release of NO was observed especially for C. albicans strain, which confirms the results obtained for microbial adhesion. Among the PDA coatings, for 0.45:0.88 (KMnO4:dopamine) molar ratio the optimal compromise was obtained in terms of antimicrobial activity and cytotoxicity, while the 0.1:1.5 ratio (KMnO4:dopamine) led to higher NO release and implicitly the reduction of the adhesion capacities only for C. albicans, being slightly cytotoxic but with moderate release of LDH. The proposed materials can be used to reduce the adhesion of yeast to the implantable material and thus inhibit the formation of microbial biofilms.

Candida albicans blastospores and hyphae respond differentially to fluconazole: additional virulence factor of germination process

Background: The morphologic transition from yeasts (blastospores) to hyphae, through the germination process, is a crucial virulence factor of Candida albicans ( C. albicans), as it enhances adherence, tissue invasion and biofilm formation. The study aimed at comparing fluconazole susceptibility patterns of C. albicans yeast and germinated forms. Methods: Six C. albicans strains, including C. albicans ATCC 10231 and 5 clinical isolates were tested in yeast forms and germinated forms for fluconazole susceptibility using CLSI M27-A3 broth microdilution and CLSI M44-A2 disk diffusion reference methods. Results: Fluconazole minimal inhibitory concentrations (MICs) were 0.125-1 µg/ml and 0.25-4 µg/ml for yeasts and germinated forms, respectively. The sensitivities of yeasts were higher than those of their corresponding germinated forms with 1 to 4-fold dilutions differences. The MIC50s of yeasts and germinated forms were 0.125 and 1 µg/ml, respectively, with 3-fold dilution difference, while MIC90s were 1 and 4 µg/ml for yeasts and germinated forms, respectively, with 2-fold dilution difference. Means of inhibition zones were 31-46.7 mm and 29.3-43.7 mm for yeasts and germinated forms, respectively. The germinated forms of all tested strains had inhibition zones smaller than those of their corresponding yeast forms with 0.2-4.8 mm differences. There was significant statistical difference in sizes of inhibition zones between yeasts and germinated forms (p = 0.043). Conclusions: Yeast and hyphae of C. albicans, both in planktonic state, respond differentially to fluconazole, as the hyphae are less sensitive than their yeasts counterparts, which can be considered as a virulence factor for hyphae, which should be considered in treatment plans of candidal infections.

Candida albicans Isolates 529L and CHN1 Exhibit Stable Colonization of the Murine Gastrointestinal Tract.

ABSTRACTCandida albicans is a pathobiont that colonizes multiple niches in the body including the gastrointestinal (GI) tract but is also responsible for both mucosal and systemic infections. Despite its prevalence as a human commensal, the murine GI tract is generally refractory to colonization with the C. albicans reference isolate SC5314. Here, we identify two C. albicans isolates, 529L and CHN1, that stably colonize the murine GI tract in three different animal facilities under conditions where SC5314 is lost from this niche. Analysis of the bacterial microbiota did not show notable differences among mice colonized with the three C. albicans strains. We compared the genotypes and phenotypes of these three strains and identified thousands of single nucleotide polymorphisms (SNPs) and multiple phenotypic differences, including their ability to grow and filament in response to nutritional cues. Despite striking filamentation differences under laboratory conditions, however, analysis of cell morphology in the GI tract revealed that the three isolates exhibited similar filamentation properties in this in vivo niche. Notably, we found that SC5314 is more sensitive to the antimicrobial peptide CRAMP, and the use of CRAMP-deficient mice modestly increased the ability of SC5314 to colonize the GI tract relative to CHN1 and 529L. These studies provide new insights into how strain-specific differences impact C. albicans traits in the host and advance CHN1 and 529L as relevant strains to study C. albicans pathobiology in its natural host niche.

Impact of Diuretics on Metabolic Activity of Urogenital Tract Microbiota in Women

Limited knowledge exists about the effects of commonly used diuretic medications on the human normal flora. Thus, we investigated potential stimulatory effects of diuretic drug furosemide on urogenital tract microbiota in women. Three strains of E. coli and C. albicans with different biofilm forming capacities were obtained from female patients diagnosed with urinary tract infections. All tested strains were treated with two different concentrations of furosemide drug, in comparison to non-treated strains as the negative control. At specific time intervals, samples were obtained from growing culture and analyzed for their proliferation rate, aspartyl proteinase excretion and biofilm formation ability. E. coli and C. albicans strains significantly increased their aspartyl proteinase excretion under furosemide treatment. This effect was frequently observed after 16 hours of incubation at 37oC. This drug has also increased the biofilm forming capacities of E. coli and C. albicans strains. Interestingly, both E. coli and C. albicans non-biofilm former strains, gained the capacity of biofilm formation when treated with furosemide at certain concentrations. E. coli control became a weak biofilm former after 48 hours of incubation, while non-biofilm former C. albicans strain became a weak biofilm former in dose-dependent fashion, after 48 hours incubation with furosemide in concentration of 0.1 mg/mL, and after 16 hours of incubation with furosemide in concentration of 0.5 mg/mL. Loop diuretic drug furosemide is able to increase the microbial virulence and turn commensal microbes into opportunistic pathogens. Additionally, the results suggest that enzyme aspartyl proteinase might act as a signal molecule for the biofilm formation, leading to the increased microbial pathogenicity.

Antifungal Effects of Voriconazole-Loaded Nano-Liposome on Fluconazole-Resistant Clinical Isolates of Candida albicans, Biological Activity and ERG11, CDR1, and CDR2 Gene Expression.

This study aimed to assess the effect of voriconazole (VCZ)-loaded nano-liposomes on biological activity and expression of ERG11, CDR1, and CDR2 genes in fluconazole (FCZ)-resistant Candida albicans. In this study, 5 resistant isolates of C. albicans and 3 susceptible clinical isolates to FCZ were scrutinized from 60 patients suspected of candidiasis. The liposomal formulation of VCZ was produced. After that, the minimum biofilm inhibitory concentration (MBIC) testing was performed and the percentage of growth inhibition was determined. Finally, ERG11, CDR1, and CDR2 mRNA levels were amplified by the quantitative reverse transcription PCR (qRT-PCR) instrument. The obtained results unveiled that VCZ-loaded nano-liposome reduction of minimum inhibitory concentration in C. albicans isolates was remarkable. The results of the MBIC in the most optimum inhibitory concentration of VCZ-loaded nano-liposome were determined to be 4.54 and 4.88 μg/mL for susceptible isolate and resistant isolate, respectively. The ERG11 gene expression in FCZ-resistant C. albicans strains in VCZ-treated, liposomal formulation of VCZ-treated, and nontreated specimens stood at 91%, 63%, and 100%, respectively. Expression levels of CDR1 genes in FCZ-resistant C. albicans were shown to be 91%, 88%, and 100%, respectively. Concerning CDR2 genes, this rate varied to 91%, 78%, and 100% in FCZ resistant, respectively. What our study unveiled was that the use of liposomal VCZ formulation could further reduce the expression of azole-resistant genes compared to VCZ itself. In addition, thanks to more efficacious penetration of the liposomal form, the rate of growth inhibition was considerably higher.

Preparation, spectroscopic characterization and antitumor-antimicrobial studies of some Schiff base transition and inner transition mixed ligand complexes

Mixed ligand complexes of Mn(II), Ni(II), Zn(II), La(III), Er(III) and Yb(III) metal ions were prepared from bidentate Schiff base ligand (L) as a primary ligand, derived from condensation of benzophenone and 1,8-naphthylenediamine, and 1,10-phenanthroline (Phen) as a secondary ligand. The new Schiff base ligand (N1-(diphenylmethylene)naphthalene-1,8-diamine) and its mixed ligand complexes were characterized by using elemental microanalysis, conductometric measurements, magnetic susceptibility and spectroscopic studies (UV–Vis, mass spectral analysis, IR, 1H NMR and SEM). In addition, their thermal analytical (TG and DTG) behavior has been reported. Measurements of the molar conductivity of the complexes in DMF solvent pointed out the electrolytic nature of all complexes except Mn(II) and Zn(II) complexes were non electrolytes. According to the elemental analyses data, it was observed that the mixed ligand chelates had the general formulae [M(L)(Phen)Cl2]Cl.2H2O (M = La(III), Er(III) and Yb(III)), [M(L)(Phen)Cl2].H2O (M = Mn(II) and Zn(II)) and [Ni(L)(Phen)Cl(H2O)]Cl.H2O. Based on these findings, all mixed ligand complexes had octahedral geometry. The SEM image of the Schiff base ligand illustrated its rods like morphology with and average particle size of 77 nm while, the image of Ni(II) complex showed non-uniform platelets structure with some scattered rods with an average particle size of 54 nm. Considerable applications were done to ensure the biological significance of Schiff base ligand and its new mixed ligand complexes with Phen against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Bacillus subtilis) and fungal (Aspergillus flavus and Candida albicans) strains and anti-cancer activities against (MCF7 breast cancer cell line). The results obtained revealed that the complexes exhibited promising biological and anticancer activity. Moreover, molecular docking studies were applied to determine the probable binding mode among the Schiff base ligand and the active site of the crystal structure of E. coli YcbB acylated with meropenem (PDB ID: 6NTW) and breast cancer estrogen mutant L536S (PDB ID: 6SBO) receptors.

Biophysical experiments reveal a protective role of protein phosphatase Z1 against oxidative damage of the cell membrane in Candida albicans

Protein phosphatase Z1 (Ppz1) has been shown to take part in important physiological functions in fungi including a contribution to virulence of Candida albicans. Although its involvement in the oxidative stress response has also been documented, the exact mechanism of action of its protective effect against oxidative damage remains unknown. By developing a pipeline to analyze the biophysical properties of the cell membrane in fungi, we demonstrate that the plasma membrane of Ppz1-KO Candida albicans displays increased sensitivity to tert-butyl-hydroperoxide-induced oxidative damage. In particular, the response to the oxidizing agent, characterized by increased lipid peroxidation, reduced lipid order, and inhibited lateral mobility of plasma membrane components, is significantly more pronounced in the Ppz1-KO C. albicans strain than in the wild-type counterpart. Remarkably, membrane constituents became almost completely immobile in the phosphatase deletion mutant exposed to oxidative stress. Furthermore, moderately elevated membrane lipid peroxidation accompanied by the aforementioned changes in the biophysical characteristics of the plasma membrane are already detectable in untreated Ppz1-KO cells indicating latent membrane damage even in the absence of oxidative stress. In conclusion, the hypersensitivity of cells lacking Ppz1 to oxidative damage establishes that potential Ppz1 inhibitors may synergize with oxidizing agents in prospective anti-fungal combination therapies.

Methanolic extract of Mitracarpus frigidus inhibits filamentation and biofilm mode of growth from multidrug resistant Candida albicans

The battery of antifungals available to treat infections caused by Candida albicans is limited and can lead to adverse effects. Treatment of these infections continues to be a challenge mainly because of the Candida resistance to multiple antifungals. The aim of this work was to investigate the antifungal activity of Mitracarpus frigidus (Willd. Ex Roem. Schult.) K. Schum methanolic extract (MFM) against virulence factors of a multidrug-resistant C. albicans strain (ATCC® 10231™). Fungal viability and morphogenesis were evaluated through microscopy techniques associated with molecular markers to detect metabolic activity and pseudohyphae formation. The potential action of MFM against biofilm proliferation and adhesion was investigated with the use of different approaches - whole slide imaging (WSI), which enables quantification of the total biofilm area, scanning electron microscopy (SEM), and analysis of the biochemical composition of the extracellular polymeric matrix. MFM treatment significantly decreased the yeast metabolic activity and the proportion of pseudohyphae. Remarkably, MFM also reduced the C. albicans pre-established biofilm and interfered with its adhesion, as identified by both WSI and SEM. Moreover, MFM affected the biofilm matrix biochemical composition by reducing mainly the concentrations of total carbohydrates and eDNA. Our findings demonstrate that the MFM has a therapeutic potential with good activity against the C. albicans virulence factors by acting against filamentation and biofilm mode of growth of this species.

Mucoadhesive gellan gum hydrogel containing diphenyl diselenide-loaded nanocapsules presents improved anti-candida action in a mouse model of vulvovaginal candidiasis

The aim of this study was to evaluate the in vitro antifungal action of a diphenyl diselenide-loaded poly(ε-caprolactone) nanocapsules suspension (NC-1) and incorporate it into a gellan gum hydrogel formulation in order to assess its in vivo efficacy in an animal model of vulvovaginal candidiasis. Nanocapsules suspensions containing the compound (NC-1 ∼ 5 mg/mL) or not (NC-B) were prepared by the interfacial deposition of preformed polymer method. To estimate in vitro antifungal effect, the broth microdilution test was applied. The results showed that NC-1 had equal or lower MIC values when compared to free compound against fifteen Candida strains. Following, the hydrogel was prepared by direct thickening of the nanocapsules suspension by gellan gum addition. The animal model of vulvovaginal candidiasis was induced by infecting female Swiss mice with Candida albicans strains. The animals were topically treated with 20 µL of hydrogels (NC-1 and free compound - 0.1 mg of diphenyl diselenide/once a day for seven days) and then the total fungal burden was assessed after the euthanasia. The results showed that the hydrogels presented pH in the acidic range, compound content close to theoretical value, homogeneous particle distribution with nanometric size, high physicochemical and microbiological stability as well as great bioadhesive property. The nano-based presented superior pharmacological action in comparison to the hydrogel containing non-encapsulated diphenyl diselenide. The results demonstrated that the nanoencapsulation maintained the effective antifungal action of diphenyl diselenide. The nano-based hydrogel formulation may be considered a promising approach against vulvovaginal candidiasis.

Candida biofilm matrix as a resistance mechanism against photodynamic therapy

BackgroundAntimicrobial photodynamic therapy (aPDT) efficiency on Candida albicans is recognized in free-floating cultures. Though, the lack of aPDT effectiveness against C. albicans organized in biofilms is still unclear. This study aimed to explore the role of the extracellular matrix (ECM) in the protection against aPDT in C. albicans biofilms. MethodsC. albicans SN 425 wild-type and two mutant strains CNJ 2302; Δ/Δefg1 and CJN 2330; Δ/Δtec1 (ECM deficient) were used. Biofilms were grown on 24-well plates and exposed twice-daily to aPDT with 44 μM toluidine blue-O (TBO) for 5 min followed by red light (635 nm) for 1 min (87.6 J/cm²) or 2 min (175.2 J/cm2). Application of just TBO, light, 0.12% chlorhexidine, and ultrapure water were used as controls. After 48 h, biofilms were assessed for dry-weight (DW), colony forming units (CFU), extracellular DNA (eDNA), soluble and insoluble protein (SP/IP), water-insoluble (alkali-soluble) polysaccharide (ASP), water-soluble polysaccharides (WSP), and confocal scanning laser microscopy. ResultsThe strains with ECM deficient were affected by aPDT. For the mutant strain Δ/Δefg1, aPDT significantly reduced CFU, ASP, DW, eDNA, WSP and IP when compared to NC (p<0.001) and for the Δ/Δtec1, aPDT significantly reduced CFU, eDNA, IP and SP. Whereas CFU, DW, ASP of the wild-type strain biofilms were not reduced (p>0.05). ConclusionsC. albicans strains with reduced ECM compounds were more sensitive to aPDT suggesting that the ECM may have a significant protection role from aPDT in C. albicans biofilms.

Immunopathogenesis of Emerging Candida auris and Candida haemulonii Strains.

The emergence of a multidrug-resistant Candida species, C. auris and C. haemulonii, has been reported worldwide. In Thailand, information on them is limited. We collected clinical isolates from Thai patients with invasive candidiasis. Both species were compared with a laboratory C. albicans strain. In vitro antifungal susceptibility and thermotolerance, and pathogenesis in the zebrafish model of infection were investigated. Both species demonstrated high minimal inhibitory concentrations to fluconazole and amphotericin B. Only C. auris tolerated high temperatures, like C. albicans. In a zebrafish swim-bladder-inoculation model, the C. auris-infected group had the highest mortality rate and infectivity, suggesting the highest virulence. The case fatality rates of C. auris, C. haemulonii, and C. albicans were 100%, 83.33%, and 51.52%, respectively. Further immunological studies revealed that both emerging Candida species stimulated genes involved in the proinflammatory cytokine group. Interestingly, the genes relating to leukocyte recruitment were downregulated only for C. auris infections. Almost all immune response genes to C. auris had a peak response at an early infection time, which contrasted with C. haemulonii. In conclusion, both emerging species were virulent in a zebrafish model of infection and could activate the inflammatory pathway. This study serves as a stepping stone for further pathogenesis studies of these important emerging species.

In vitro Insights into Prospect of Cnestis ferruginea Pulp Extract as an Antimicrobial Agent

Sensitivity study of Cnestis ferruginea pulp extract with respect to the reference commercial antibiotics was tested against four bacteria (Staphylococcus aureus, Bacillus subtilis, Proteus mirabilis, and Klebsiella pneumoniae) and three fungi (Trichoderum rubrum, Aspergillus niger, and Candida albicans) strains isolated in man with a view to elucidating the inhibitory potency of the plant pulp’ extract using an agar well diffusion assay. The investigation discovered that the extract had 71% inhibitory activities against the microbial isolates tested either in sterilized or non-sterilized form and in the two different concentrations examined, which compared favourably with reference antibiotics used. The optimal performance of the pulp extract against the test organisms could be due to the presence of the metabolites such as alkaloids, flavonoids, steroids, saponins, and polyphenols found in ample form in the extract. This study has revealed the possible utilization of Cnestis ferrugineain the treatment of wound, urinary infections and in the management of oral-related infections.

Synthesis, Cytotoxicity Evaluation, and Antifungal Activity of Novel Nitroglycerin Derivatives against Clinical Candida albicans Isolates.

Background:Candida albicans remains the main cause of candidiasis in most clinical settings. Available drugs for candidiasis treatment have many side effects. In this work, novel nitroglycerin derivatives were synthesized and their cytotoxic and antifungal effects evaluated against fluconazole susceptible and resistant clinical C. albicans isolates.Methods:This experimental study was performed in Tehran University of Medical Sciences and Baqiatallah University of Medical Sciences, Tehran, Iran between Feb to Dec 2019. The in vitro activities of two novel nitroglycerin derivatives (1b and 2b) against 25 clinical fluconazole-susceptible and resistant C. albicans isolates and four standard C. albicans strains were determined according to CLSI reference M27-A3 documents. The cytotoxicity of chemical compounds was investigated near the SNL76/7 cells by colorimetric assay. Real-time PCRs were performed to evaluate the alterations in the regulation of ERG11 and CDR1 genes under nitroglycerin derivatives-treated and untreated conditions.Results:The derivatives 1b and 2b exhibited potent antifungal activity against C. albicans isolates; MICs and MFCs varied from 18 μg/ml to 72 μg/ml and 36 μg/ml to 144 μg/ml, respectively. The cell viability evaluation demonstrated that both chemical compounds are safe within 24h. The nitroglycerin derivatives were able to reduce the transcription level of CDR1 and ERG11 genes in all susceptible and resistant C. albicans isolates.Conclusion:Considering the potential and efficacy of these compounds against clinical C. albicans isolates, the complementary in vivo and clinical trials should be investigated.

Identification of Clinical Isolates of Candida albicans with Increased Fitness in Colonization of the Murine Gut.

The commensal and opportunistic pathogen Candida albicans is an important cause of fungal diseases in humans, with the gastrointestinal tract being an important reservoir for its infections. The study of the mechanisms promoting the C. albicans commensal state has attracted considerable attention over the last few years, and several studies have focused on the identification of the intestinal human mycobiota and the characterization of Candida genes involved in its establishment as a commensal. In this work, we have barcoded 114 clinical C. albicans isolates to identify strains with an enhanced fitness in a murine gastrointestinal commensalism model. The 114 barcoded clinical isolates were pooled in four groups of 28 to 30 strains that were inoculated by gavage in mice previously treated with antibacterial therapy. Eight strains that either exhibited higher colonization load and/or remained in the gut after antibiotic removal were selected. The phenotypic analysis of these strains compared to an RFP-tagged SC5314 wild type strain did not reveal any specific trait associated with its increased colonization; all strains were able to filament and six of the eight strains displayed invasive growth on Spider medium. Analysis of one of these strains, CaORAL3, revealed that although mice required previous bacterial microbiota reduction with antibiotics to be able to be colonized, removal of this procedure could take place the same day (or even before) Candida inoculation. This strain was able to colonize the intestine of mice already colonized with Candida without antibiotic treatment in co-housing experiments. CaORAL3 was also able to be established as a commensal in mice previously colonized by another (CaHG43) or the same (CaORAL3) C. albicans strain. Therefore, we have identified C. albicans isolates that display higher colonization load than the standard strain SC5314 which will surely facilitate the analysis of the factors that regulate fungal colonization.

Anticandidal activity of dichloromethane extract obtained from the red algae A. armata of the Algerian coast

This work reports for the first time the anticandidal activity of the dichloromethane (DCM) extract from the Algerian invasive red marine algae A. armata Harvey. In a preliminary assessment, the DCM extract was screened for its antifungal activity against two strains of Candida albicans, namely (IP 444) and (ATCC 10231). As a well-established approach, the anticandidal activity was expressed as zone of inhibition by agar well and disk diffusion methods. The minimum inhibitory concentration (MIC) was also determined for the two fungal strains. Within this framework, the DCM extract of the red algae A. armata has a strong inhibition effect against the considered Candida albicans strains. In addition, Candida albicans IP444 (MIC = 0.58 mg/mL) was more sensitive to DCM algal extract when compared to Candida albicans ATCC 10231 (MIC = 2.34 mg/mL). GC–MS analysis suggested that brominated compounds and fatty acids are responsible for anticandidal activity of dichloromethane extract of A. armata. These preliminary results may constitute a future applied of lipophilic extract of the red algae A. armata as a promising source of natural compounds with antifungal properties.