Candida Albicans Strains Research Articles

BIOLOGICAL ACTIVITY EVALUATION OF THREE Hypericum L. SPECIES

This study was performed in order to evaluate in vitro antioxidant, anti-Trichomonas vaginalis, antimicrobial and cytotoxic activities of methanol extracts of aerial parts of Hypericum perforatum L., H. thymbrifolium Boiss. & Noë and H. thymopsis Boiss. The antioxidant activity of methanol extracts was tested with 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging and iron chelating assays. The total phenol and flavonoid contents were also determined spectrophotometrically. Cytotoxicity and apoptosis were evaluated on MCF-7 breast cancer and PC3 prostate cancer cell line. Antimicrobial activities were evaluated by the microdilution method on the bacterial strains Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853) Escherichia coli (ATCC 25922) and the fungal strain Candida albicans (ATCC 10231). All extracts demonstrated cytotoxic activity on PC3 prostat cancer cell line with a concentration dependent manner, while H. thymopsis extract was the most active against cancer cell growth. The obtained results of the present study revealed that the methanol extract of H. perforatum, H. thymbrifolium and H. thymopsis have significant antioxidant and cytotoxic activities. The results provided the basic research data for further phytochemical and biological activity guided investigations on these species for identication and isolation of potential drug active compounds.

Metallacarborane Derivatives as Innovative Anti-Candida albicans Agents.

Infections caused by Candida species have increased significantly in the past decades and are among the leading causes of morbidity and mortality worldwide, resulting in serious public health problems. Currently, conventional antifungals are often ineffective as Candida spp. have developed growing resistance to systemic drugs. Since inorganic metallacarboranes are known to affect cellular events, new derivatives of these abiotic compounds were tested against Candida albicans. Compounds based on cobalt bis-dicarbollide [COSAN] were studied on Candida albicans strains, including a panel of 100 clinical isolates. The presented data prove that metallacarborane derivatives are effective against clinical isolates of Candida albicans, even those resistant to systemic drugs, and show synergistic potential in combination with amphotericin B, and low toxicity against human cells and Danio rerio embryos. This paper is a consequential step in the investigations of the broad spectrum and valuable future medical applications of metallacarboranes, especially in the fight against drug-resistant pathogens.

Phytochemical Screening, Antioxidant, and Antimicrobial Activities of Seven Underinvestigated Medicinal Plants against Microbial Pathogens.

Background Plants are a rich source of therapeutic compounds that have tremendous applications in the pharmaceutical industry. This study aimed to identify the phytochemicals present in the seven selected medicinal plants as well as their antioxidant and antimicrobial activities. Methods Phytochemical screening, total phenolic, and flavonoid contents were determined using standard methods. The antioxidant activity of plant extracts was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), and nitric oxide (NO) radical scavenging assays. The antimicrobial activity of the plant extracts was determined by the broth microdilution method. Results The results of phytochemical analysis showed the presence of phenols, flavonoids, and steroids in all plant extracts. The extract of Psychotria peduncularis showed the highest total phenolic and flavonoid contents (5.57 ± 0.22 mg GAE/g and 1.38 ± 0.06 mg QE/g, respectively). All plant extracts showed very strong antioxidant activity against DPPH and NO radical scavenging with IC50 values ranging from 0.55 to 49.43 µg/mL and 0.65 to 13.7 µg/mL, respectively. The extracts of Tristemma mauritianum and P. peduncularis displayed significant antibacterial activity with MIC values ranging from 16 to 1024 µg/mL. T. mauritianum extract showed bactericidal activity against all tested species. The extracts of Alsophila manianna and P. peduncularis showed significant antifungal activity (MIC = 64 µg/mL) against Candida albicans strain. Conclusion The screened extracts of medicinal plants used in our study can be used as potential antioxidant and antimicrobial agents, and resources for the development of new drugs.

Biased Genotype Distributions of Candida albicans Strains Associated with 649 Clinical Vulvovaginal Candidiasis in China.

Vulvovaginal candidiasis (VVC), which is most frequently caused by Candida albicans, is a common problem worldwide. Despite the fact that extensive epidemiological studies have been performed, the cause of recurrent VVC (RVVC) remains uncertain. The aims of this work were to compare the genotypes of C. albicans strains causing different conditions of VVC, and explore the relationship between the drug resistance and genotype of C. albicans strains. In our study, we collected 649 independent strains from VVC patients in China. Isolates were tested for in vitro susceptibility to fluconazole, itraconazole, voriconazole, amphotericin B and caspofungin in accordance with the Clinical Laboratory Standards Institute (CLSI) document M27-A3. Genotyping was performed using PCR targeting specific CAI locus marker. C. albicans is the main pathogen of VVC, but the proportion of non-candida albicans (NAC) infection is also increasing, and we also found increased cases of mixed infection. Some C. albicans are resistant to multiple drugs. The strains with the genotypes including 16-16, 18-18 and 22-22 was likely to be the dominant genotype of uncomplicated VVC (p < 0.05). The genotypes of complicated VVC are mainly distributed in 30-45, 33-45, 32-46 and 39-45. Strains of 30-45, 32-45, 30-47 and 30-46 genotypes showed resistance to fluconazole, itraconazole, voriconazole and amphotericin B respectively. Our work suggests that the dominant genotypes with higher repeat number of C. albicans strains were more prevalent in patients with RVVC and drug-resistant strains, however, strains with uncomplicated VVC were more likely to distribute in homozygous. Identification of specific genotypes that correlate with different conditions of VVC and drug resistant is also of diagnostic and therapeutic significance.

Green Preparation of Antimicrobial 1D-Coordination Polymers: [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞ by Ultrasonication of Zn(II) Salts and 4,4'-Bipyridine.

We report on the green preparation of one-dimensional metal coordination polymers by sonochemical approach. The spacer ligand 4,4′-bipyridine was ultrasonicated with chloride or acetate zinc salts to obtain [Zn(4,4′-bipy)Cl2]∞ and [Zn(4,4′-bipy)2(OAc)2]∞, respectively. Benign solvents such as ethanol and water were selected as reaction media, and the synthesis took place in a few minutes—a very short time compared to conventional methods where some days’ synthesis is required. X-ray powder diffraction, Fourier transform infrared spectroscopy, thermal analysis (thermogravimetric and differential scanning calorimetry), and CHN techniques investigated the influence of using different reaction solvents on the chemical, structural, and thermal properties of the final products. The 1D [Zn(4,4′-bipy)Cl2]∞ and [Zn(4,4′-bipy)2(OAc)2]∞ polymers, in agreement with the structures reported in the literature, were obtained in the form of nanocrystals with an average crystal size around 100 nm. As a proof of concept, a set of Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae), and three yeast strains (Candida albicans, Candida krusei, Candida glabrata) were tested to evaluate the antimicrobial activity of the coordination polymers, following the Kirby–Bauer procedure and microplate dilution method. Thus, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimal biofilm inhibitory concentration (MBIC) were evaluated. Except for Candida krusei, the compounds showed an appreciable antimicrobial and antibiofilm activity against these strains grown in the liquid medium.

Evaluation of the Antifungal Activity of Five Medicinal Plants on the in vitro Growth of a Multi-resistant Strain of Candida Albicans

This study was conducted to determine the antifungal potential of plants traditionally used in the treatment of infections. Five (5) plants were collected. The anti-candida albicans activity was evaluated by the double dilution method in tilted tubes with the aqueous and hydroethanolic extracts of the different plants. The results showed that the 70% ethanolic extracts were more active than the aqueous extracts for all plants. The 70% ethanolic extract of T. ivorensis (FMC = 1.56 mg/ml) was the most active on the tested strain. It was followed by T. superba (MFC = 3.125 mg/ml) D. benthamianus (MFC = 50 mg/mL), G. arborea (MFC= 50 mg/mL) and J. secunda (MFC ˃ 50 mg/mL). The phytochemical screening revealed the presence of seven major groups of compounds, among which saponins and catechins are the most abundant in the aqueous extracts. Polyphenols, Flavonoids, Polyterpenes and Sterols as well as Tannins are equally present in the alcoholic and aqueous extracts of the different plants at variable levels. These compounds could justify its activity and its traditional use.

Synthesis of the novel cage amides and imides and evaluation of their antibacterial and antifungal activity

Cage amides and imides bearing bicyclo[2.2.1]- and bicyclo[2.2.2]-subunits were synthesized and evaluated both for antimicrobial activity toward five key ESKAPE pathogenic bacteria: one Gram‐positive bacteria methicillin‐resistant Staphylococcus aureus (ATCC 43300), four Gram‐negative bacteria Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 700603), Acinetobacter baumannii (ATCC 19606) and Pseudomonas aeruginosa (ATCC 27853) and for antifungal activity towards pathogenic fungal strains Candida albicans (ATCC 90028) and Cryptococcus neoformans var. Grubii (H99; ATCC 208821). Compound VP-4539 with bicyclo[2.2.2]octene motif demonstrated the highest cytotoxic activity towards C. neoformans, while human keratinocytes of HaCaT line, murine fibroblasts of Balb/c 3T3 line and mitogen-activated lymphocytes of peripheral human blood were found to be tolerant to its action. VP-4539 compound did not intercalate into salmon sperm DNA indicating that its cytotoxicity is not related to intercalation into nucleic acid. Keywords: antifungal, antimicrobial, bicyclo[2.2.1]heptane, bicyclo[2.2.2]octene, cytotoxicity, DNA intercalation, human keratinocytes, lymphocytes, сage compounds

Design, synthesis and antimicrobial studies of novel imine derivatives of 2-(6H-indolo[2,3-b]quinoxalin-6-yl)-1-phenylethan-1-ones

A series of new imine derivatives 2-(6H-indolo[2,3-b]quinoxalin-6-yl)-1-phenylethan-1-ones was synthesized by various methods in good yields and characterized through IR, NMR and Mass spectral analysis. Some compounds were screened for their in vitro antimicrobial activity against five bacterial and one fungal pathogens. Compound 4a showed greater efficiency than Rivanol against gram-negative bacteria Escherichia coli and Proteus Vulgaris and a fungal strain of Candida albicans.

Tropical Medicinal Plant Extracts from Indonesia as Antifungal Agents against Candida Albicans.

Candida albicans is responsible for a wide range of medical ailments, from harmless cutaneous to life-threatening bloodstream infections. Growing cases of antifungal-drug resistance strains of C. albicans become a rationale to explore and develop novel anti-candida agents. In this paper, we assessed the anti-candida activity of the methanolic extracts of various tropical medicinal plants from Myrtaceae, Poaceae, and Zingiberaceae, commonly used in Indonesia to treat fungal infections. Candida albicans strain ATCC 10231 was used as a subject to assess the anti-Candida activities of plant methanolic extracts through disc diffusion assay. Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) were observed. All plant extracts in this study showed antifungal activities against C. albicans. Among them, Cymbopogon citratus, Curcuma xanthorrhiza, Curcuma aeruginosa, and Zingiber officinale var. rubrum showed the lowest MIC and MFC value of 3.8 mg/mL. The growth inhibition of C. albicans on disc diffusion assay was demonstrated by Z. officinale var. rubrum and C. longa, which were comparable to antifungal nystatin. Further investigation of the chemical constituents of the extracts and the cytotoxicity test is needed to further develop plant-derived anti-candida agents.

Assessment of Biofilm Formation by Candida albicans Strains Isolated from Hemocultures and Their Role in Pathogenesis in the Zebrafish Model.

Candida albicans, an opportunistic pathogen, has the ability to form biofilms in the host or within medical devices in the body. Biofilms have been associated with disseminated/invasive disease with increased severity of infection by disrupting the host immune response and prolonging antifungal treatment. In this study, the in vivo virulence of three strains with different biofilm formation strengths, that is, non-, weak-, and strong biofilm formers, was evaluated using the zebrafish model. The survival assay and fungal tissue burden were measured. Biofilm-related gene expressions were also investigated. The survival of zebrafish, inoculated with strong biofilms forming C. albicans,, was significantly shorter than strains without biofilms forming C. albicans. However, there were no statistical differences in the burden of viable colonogenic cell number between the groups of the three strains tested. We observed that the stronger the biofilm formation, the higher up-regulation of biofilm-associated genes. The biofilm-forming strain (140 and 57), injected into zebrafish larvae, possessed a higher level of expression of genes associated with adhesion, attachment, filamentation, and cell proliferation, including eap1, als3, hwp1, bcr1, and mkc1 at 8 h. The results suggested that, despite the difference in genetic background, biofilm formation is an important virulence factor for the pathogenesis of C. albicans. However, the association between biofilm formation strength and in vivo virulence is controversial and needs to be further studied.

Correlation between SAP2 and CAP1 in clinical strains of Candida albicans at planktonic and biofilm states.

This study aimed to explore the influences of SAP2 and CAP1 on itraconazole (ITR) resistance of Candida albicans at different states. A total of 10 ITR-resistant strains and 10 ITR-sensitive strains were used for SAP2 sequencing and CAP1 sequencing. SAP2 sequencing showed no missense mutation, and three synonymous mutations. CAP1 gene sequencing identified two missense mutations M140I (8) and K191Q (4), and 14 synonymous mutations G201A (1), A246C (5), C282T (6), G288A (6), C321T (7), A399C (16), C432T (16), C465T (11), G552A (16), G669T (1), G672A (1), G681T (2), T783C (1), and T819A (2). The biofilm formation capacity of resistant C. albicans strains, including the CAP1∆/∆ strain, was stronger. Afterward, real-time quantitative PCR was used to analyze the expression of SAP2 and CAP1. Compared with the sensitive strains, SAP2 and CAP1 expressions were both significantly upregulated in resistant strains at planktonic and biofilm states (P<0.05). Compared with the strains at planktonic state, SAP2 was significantly upregulated, while CAP1 was significantly downregulated at biofilm states (P<0.05). Additionally, SAP2 expression in the CAP1 knocked down strain of C. albicans was significantly upregulated, and SAP2 expression was evidently downregulated in the CAP1∆/∆ strain at biofilm states compared with that at planktonic states (P<0.05). Loss of CAP1 can increase SAP2 level and may influence the biofilm formation of C. albicans, thus increasing ITR resistance ofC. albicans.

An in vitro study of interactions of Candida albicans with Klebsiella pneumoniae and Enterococcus faecalis isolated from intestinal microbiome of HIV infected patients

The aim: In vitro identification of targets for antagonism factors in klebsiellas and enterococci for Candida albicans isolated from the intestinal microbiome of HIV infected patients.Materials and methods. The tests were performed using 38 Candida albicans strains, 28 Klebsiella pneumoniae strains, and 30 Enterococcus faecalis strains isolated from the intestinal microbiome of 89 HIV infected children. The mean age of the patients was 24 ± 2 months; the group consisted of 49 (55%) boys and 40 (45%) girls. Microorganisms were isolated from the intestinal biotope using such selective media as HiChrome Candida Agar, HiChrome Klebsiella Selective Agar Base, and Enterococcus Agar; the study included identification of species. Model experiments were performed to study anti-catalase activity of E. faecalis exometabolites and the impact of K. pneumoniae on morphological transformation of C. albicans fungi.Results. Klebsiellas decrease the intensity of germ tube formation in C. albicans by 58.7% (p 0.01). When cocultured, 12.3% of the yeast cells produce germ tubes, while 29.8% of transformed cells was detected in the fungal monoculture. It has been found that exometabolites of 65.7% of E. faecalis strains decrease production of catalase in C. albicans. The initial catalase level in untreated cultures of C. albicans averages 1.02 µmol/min of optical density; after they are treated with E. faecalis exometabolites, the level decreases to 0.55 µmol/min, i.e. by 46.1% (p 0.05).Conclusions. K. pneumoniae and E. faecalis demonstrate antagonism of different intensity toward C. albicans. Morphological transformation and catalase production are targets for antagonism factors of facultative microbiota in C. albicans.

Woodfordia fruticosa extract nanoemulsion: Influence of processing treatment on droplet size and its assessment for in vitro antimicrobial and anti-inflammatory activity.

Recently, plant-derived bioactive compounds have been utilized in the preparation of several functional food products; however, stability and water solubility are major constraints to these compounds. Therefore, to overcome this problem, the synthesis of nanoemulsion (oil in water) with varying concentrations of Woodfordia fruticosa flower extract (1%−10% w/v) was carried out and characterization of nanoemulsion was done. The average droplet size of nanoemulsion samples ranges from 149.25 to 244.33 nm. The control and WFNE3 nanoemulsion showed significantly (p < 0.05) higher thermal stability when correlated with average droplet size. An insignificant difference (p > 0.05) was observed in the average droplet size and zeta potential WFNE3 (−30.3mV) with the increased temperature rate. At varied pH ranges, WFNE3 showed significantly higher (p < 0.05) stability in comparison with the control nanoemulsion sample. In terms of ionic strength, WFNE3 nanoemulsion sample showed significantly (p < 0.05) higher stability, and with an increasing concentration of salt, the colloidal system of the WFNE3 sample showed significantly (p < 0.05) higher droplet size (318.91 nm). Therefore, the antimicrobial potential of WFNE3 nanoemulsion in comparison with extract of W. fruticosa flower extract was studied against Gram-positive Staphylococcus aureus, Gram-negative bacteria Pseudomonas aeruginosa, and fungal strain Candida albicans, respectively. WFNE3 nanoemulsion sample in comparison to flower extract showed a significantly higher (p < 0.05) zone of inhibition against gram-negative bacteria as compared to the control nanoemulsion sample upon storage for 7 days. WFNE3 nanoemulsion sample showed significant (p < 0.05) higher inhibition of protein denaturation (57.89%−87.65%) and (55.36%−83.58%) in comparison to control nanoemulsion sample (54.67%−80.28%) and flower extract (51.56%−79.36%), respectively. Due to these biological activities, the WFNE3 nanoemulsion sample could be scaled up to the industrial level for the formulation of varied types of functional foods.

Evaluation of the Antifungal Activity of Five Medicinal Plants on the in vitro Growth of a Multi-resistant Strain of Candida Albicans

This study was conducted to determine the antifungal potential of plants traditionally used in the treatment of infections. Five (5) plants were collected. The anti-candida albicans activity was evaluated by the double dilution method in tilted tubes with the aqueous and hydroethanolic extracts of the different plants. The results showed that the 70% ethanolic extracts were more active than the aqueous extracts for all plants. The 70% ethanolic extract of T. ivorensis (FMC = 1.56 mg/ml) was the most active on the tested strain. It was followed by T. superba (MFC = 3.125 mg/ml) D. benthamianus (MFC = 50 mg/mL), G. arborea (MFC= 50 mg/mL) and J. secunda (MFC ˃ 50 mg/mL). The phytochemical screening revealed the presence of seven major groups of compounds, among which saponins and catechins are the most abundant in the aqueous extracts. Polyphenols, Flavonoids, Polyterpenes and Sterols as well as Tannins are equally present in the alcoholic and aqueous extracts of the different plants at variable levels. These compounds could justify its activity and its traditional use.

Anti-Candida activity and industrial properties of Pediococcus pentosaceus NOA-2142 isolate from traditional pickled gherkin

Antifungal activities of LAB have increased in many environments, especially in foods, due to the harms of chemical preservatives, as they are natural and capable of preventing both spoilage and infections. This antifungal activity is associated with metabolic compounds of LAB such as cyclic dipeptides, fatty acids, hydrogen peroxide, organic acids, and phenyl lactic acid (PLA) which are produced directly or indirectly. On the other hand, many Candida sp. such as Candida albicans is an opportunistic pathogen and can cause diseases ranging from superficial mucosal to life-threatening systemic infections, and spoilage in food. Therefore, the anti-candida activity of LAB is an important issue. In this study, it was aimed to reveal the anti-candida activity of Pediococcus pentosaceus NOA-2142 which isolated from a traditional pickled gherkin, and to investigate the industrial properties of this strain for widespread use. In the study, the NOA-2142 isolate was selected for its high anti-candida activity, and was determined to belong to P. pentosaceus species. Subsequently, the minimum inhibitory concentration (MIC) of the cell-free supernatant (CFS) of this isolate against pathogen strains of Candida albicans and Candida tropicalis was determined as 1/128 and 1/64, respectively. In addition, the D-3-phenyllactic acid content, which is the most likely cause of the anti-candida activity of the CFS, was determined as 163.21 mg/L. Moreover, the isolate were revealed to have the ability to grow at temperatures of 15oC and above, and in the range of 3–12% NaCl concentration and 3.0–9 pH value. The NOA-2142 isolate showed the highest susceptibility with 40.53 mm zone diameter to the clindamycin antibiotic disc. As a result, the P. pentosaceus NOA-2142 with antifungal potential could be a proper candidate as bio-preservative starter or adjunct culture, or the CFS of P. pentosaceus NOA-2142 could be used as a natural additive.

In Vitro Antibacterial Activity of Some Plant Essential Oils against Four Different Microbial Strains

This study evaluates the antimicrobial and antioxidant activities of five essential oils (EO): pine oil, thyme oil, sage oil, fennel oil, and eucalyptus essential oils. To identify the chemical composition of the essential oils, we used gas chromatography coupled to a mass spectrometer (GC-MS). EO are predominantly characterized by the presence of monoterpene hydrocarbons and oxygenated monoterpenes, except in the case of fennel essential oil which contains phenylpropanoids as its main components. The antimicrobial activity of the EO was highlighted on four standard microbial strains (two Gram-negative strains-Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853; one Gram-positive strain Staphylococcus aureus ATCC 25923, and one yeast strain-Candida albicans ATCC 10231). Antimicrobial activity was assessed by measuring the diameter of the inhibition zone, and by determining the values of the minimum inhibitory concentration (MIC) and minimum concentration of biofilm eradication (MCBE). Analyzing the diameter values of the inhibition zones we observed increased efficiency of thyme essential oil, which showed the highest values for all tested microbial species. The results of tests performed in a liquid confirm the high sensitivity of the standard strain Escherichia coli ATCC 25922 to the action of all essential oils, the lowest values of MIC being recorded for sage and thyme essential oils. For the most essential oils tested in this study, the MCBE values are close to the MIC values, except for the pine EO which seems to have stimulated the adhesion of the yeast strain at concentrations lower than 5%. The study highlights the antimicrobial activity of the tested essential oils on Gram-positive and Gram-negative strains.

P003 Synthetic antifungal peptide mimic kills Candida albicans by targeting protein glycosylation and synergistically prevents infection

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMFungal infections represent a serious burden on human health. Increasing numbers of susceptible hosts, a limited set of approved antifungal drugs which frequently trigger undesired side effects, and the emergence of resistant strains highlight the urgent demand for novel antifungal drug formulations. However, the biological similarity of human and fungal cells hampers the development of new antifungals which do not also harm humans. In nature, organisms in almost all domains of life produce antimicrobial peptides to combat microbial pathogens. Those peptides share certain characteristics, such as being short, amphiphilic molecules with a positive net charge.1 We designed synthetic polyacrylamides which mimic the properties of naturally occurring antifungal peptides. These positively charged, amphiphilic polymers are advantageous over peptides because of their easy synthesis and stability against proteases. Initial structure-activity relationship studies revealed an optimal cLogP (the calculated hydrophobicity of a molecule) around 1.5 to ensure activity against C. albicans and simultaneous biocompatibility with host cells.2 Additionally, shorter polymers with a length of 20 subunits were more effective than their longer versions.2 In terms of their therapeutic index, certain compositions outperformed the broad-spectrum antifungal amphotericin B and were even effective against drug-resistant clinical isolates of C. albicans.2 Candida albicans strains with known antifungal drug-resistance mutations were not affected in their susceptibility to the polymers. Therefore, investigations were carried out to elucidate the mode of action of the polymers. The transcriptome of C. albicans cells treated with subinhibitory concentrations of the polymers revealed an increased expression of genes involved in general stress response and upregulation in protein processing in the endoplasmic reticulum, particularly glycosylation and degradation. These findings, together with electron microscopy observations, indicated damage to the mannoproteins in the cell wall of the fungus. Membrane damage was also observed utilizing a C. albicans strain expressing GFP intracellularly. The in vitro therapeutic potential of the most promising polymer was tested in a human epithelial cell (HEC) model simulating C. albicans infection. The polymer alone was not able to prevent C. albicans infection of HECs. However, the combination of polymer with caspofungin or fluconazole showed very strong synergistic effects at otherwise non-inhibitory concentrations of the individual antifungals, successfully stopping fungal infection in vitro without damaging the HECs. These results underline the potential of synthetic polymers as an alternative treatment for fungal infections with low toxicity to human cells and a novel mode of action.Sources1. Fernández de Ullivarri, M., Arbulu, S., Garcia-Gutierrez, E. and Cotter, P.D. Antifungal peptides as therapeutic agents. Front Cell Infect Microbiol 10, 00 105 (2020).2. Schaefer, S. et al. Rational design of an antifungal polyacrylamide library with reduced host-cell toxicity. ACS Appl Mater Interfaces 13, 27430-27444 (2021).

P342 Lactobacillus rhamnosus protection against Candida-induced vaginal epithelial cell damage is Candida albicans strain-dependent

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PMMicrobial dysbiosis can lead to vulvovaginal candidiasis (VVC) which is characterized by a pathogenicity-induced inflammatory response progressing to neutrophil-driven immunopathology. Probiotic treatment has varied success rates and some women still experience VVC despite being colonized by lactobacilli. It is, therefore, imperative to identify factors that influence the success of probiotic treatment for VVC.We aimed to evaluate how Candida albicans strain differences contribute to the varying degrees to which probiotics such as Lactobacillus rhamnosus protect against Candida-induced epithelial tissue damage. We screened the commonly used highly virulent C. albicans laboratory strain SC5314, 24 C. albicans strains from different clades, and several vaginal C. albicans isolates. L. rhamnosus was used to colonize vaginal epithelial cells prior to C. albicans infection and vaginal epithelial cell damage was measured.Compared to SC5314, most C. albicans strains induced relatively low or no epithelial cell damage. Even increased multiplicities of infection did not increase epithelial damage to the level of SC5314. Three groups were identified based on the effect of L. rhamnosus on Candida-induced epithelial cell damage. Bacterial colonization decreased, did not affect, or even increased tissue damage during infection.The different C. albicans clades showed no correlation with the protective phenotypes. However, increased epithelial tissue damage in the presence of lactobacilli was generally observed with strains that alone were unable to damage the epithelium. Some strains had an enhanced potential to grow at low pH, yet growth at low pH alone was not able to distinguish the three groups.The protective potential of L. rhamnosus is highly C. albicans strain-dependent. Our data hint toward a potential multifactorial effect involving stress-resistance and metabolic interplay. Elucidating the processes that lead to epithelial protection or enhanced damage will be crucial to predict whether probiotic lactobacilli may be beneficial or detrimental for a patient and may help to design generally protective probiotics.

Antioxidative and Photo-Induced Effects of Different Types of N-Doped Graphene Quantum Dots.

Due to the increasing number of bacterial infections and the development of resistivity toward antibiotics, new materials and approaches for treatments must be urgently developed. The production of new materials should be ecologically friendly considering overall pollution with chemicals and economically acceptable and accessible to the wide population. Thus, the possibility of using biocompatible graphene quantum dots (GQDs) as an agent in photodynamic therapy was studied. First, dots were obtained using electrochemical cutting of graphite. In only one synthetic step using gamma irradiation, GQDs were doped with N atoms without any reagent. Obtained dots showed blue photoluminescence, with a diameter of 19–89 nm and optical band gap of 3.23–4.73 eV, featuring oxygen-containing, amino, and amide functional groups. Dots showed antioxidative activity; they quenched •OH at a concentration of 10 μg·mL−1, scavenged DPPH• radicals even at 5 μg·mL−1, and caused discoloration of KMnO4 at 30 μg·mL−1. Under light irradiation, dots were able to produce singlet oxygen, which remained stable for 10 min. Photoinduced effects by GQDs were studied on several bacterial strains (Listeria monocytogenes, Bacillus cereus, clinical strains of Streptococcus mutans, S. pyogenes, and S. sangunis, Pseudomonas aeruginosa, and one yeast strain Candida albicans) but antibacterial effects were not noticed.

Chelerythrine reverses the drug resistance of resistant Candida albicans and the biofilm to fluconazole.

Aim: To evaluate the antifungal activity of chelerythrine in combination with fluconazole against planktonic Candidaalbicans strains and preformed biofilm. Materials & methods: A broth microdilution assay was used to reveal the antifungal activity of chelerythrine combined with fluconazole against C. albicans and the preformed biofilm. A fractional inhibitory concentration index model was used to evaluate the interaction. Results: Chelerythrine strongly synergized with fluconazole against fluconazole-resistant C. albicans and the biofilm preformed forless than 12h. In addition, chelerythrine combined with fluconazole exhibited asynergistic effect against C. albicans morphogenesis. Conclusion: Chelerythrine could reverse the drug resistance of resistant C. albicans and its biofilm to fluconazole, providing new insights for overcoming the drug resistance of C. albicans.