Inhibit Biofilm Formation Research Articles

Streptokinase reduces Streptococcus dysgalactiae subsp. equisimilis biofilm formation

BackgroundStreptococcus dysgalactiae subspecies equisimilis (SDSE) is increasingly recognized as an emerging cause of invasive diseases including necrotizing soft tissue infections (NSTIs). In contrast to the closely related Streptococcus pyogenes, SDSE infections mainly affect older and comorbid patients. Biofilm formation has been demonstrated in soft tissue biopsies of S. pyogenes NSTI cases.ResultsHere, we show that bacterial aggregations indicative of biofilms are also present in SDSE NSTI. Although streptokinase (Ska) activity and biofilm formation did not correlate in a diverse set of clinical SDSE isolates, addition of exogenous Ska at an early time point prevented biofilm formation for selected strains. Deletion of ska in SDSE S118 strain resulted in increased biofilm forming capacity. Ska-deficient mutant strain was characterized by a higher metabolic activity and consequent metabolome profiling of biofilms identified higher deposition of a wide range of metabolites as compared to the wild-type.ConclusionsOur results argue that Ska suppresses biofilm formation in SDSE independent of its original plasminogen converting activity. However, the impact of biofilms and its consequences for patient outcomes in streptococcal NSTIs remain to be elucidated.

Novel nanoconjugates of metal oxides and natural red pigment from the endophyte Monascus ruber using solid-state fermentation

BackgroundAntimicrobial resistance has emerged as a major global health threat, necessitating the urgent development of new antimicrobials through innovative methods to combat the rising prevalence of resistant microbes. With this view, we developed three novel nanoconjugates using microbial natural pigment for effective application against certain pathogenic microbes.ResultsA natural red pigment (RP) extracted from the endophyte Monascus ruber and gamma rays were applied to synthesize RP-ZnO, RP-CuO, and RP-MgO nanoconjugates. The synthesized nanoconjugates were characterized by different techniques to study their properties. The antimicrobial potential of these nanoconjugates was evaluated. Moreover, the antibiofilm, protein leakage, growth curve, and UV light irradiation effect of the synthesized nanoconjugates were also studied. Our results confirmed the nano-size, shape, and stability of the prepared conjugates. RP-ZnO, RP-CuO, and RP-MgO nanoconjugates showed broad antimicrobial potential against the tested bacterial and fungal pathogens. Furthermore, the RP-ZnO nanoconjugate possessed the highest activity, followed by the RP-CuO against the tested microbes. The highest % inhibition of biofilm formation by the RP-ZnO nanoconjugate. Membrane leakage of E. coli and S. aureus by RP-ZnO nanoconjugate was more effective than RP-MgO and RP-CuO nanoconjugates. Finally, UV light irradiation intensified the antibiotic action of the three nanoconjugates and RP-ZnO potential was greater than that of the RP-MgO, and RP-CuO nanoconjugates.ConclusionThese findings pave the way for exploiting the synthesized nanoconjugates as potential materials in biomedical applications, promoting natural, green, and eco-friendly approaches.

Exploring the probiotic potential of Lactiplantibacillus pentosus SM1: Resistance, anti-microbial activity, anti-biofilm, cytotoxic activity, and safety properties

Lactiplantibacillus pentosus SM1 displayed notable resistance to acidic environments, with over 76% survival after 3 h in low pH conditions, and demonstrated viability in simulated gastrointestinal fluids. The Lpb. pentosus SM1 exhibited surface hydrophobicity, auto-aggregation, co-aggregation, and adhesion values of 59.60%, 38.80%, 44.90%, and 13.10% respectively. The anti-adhesion capability of Lpb. pentosus SM1 against Listeria monocytogenes adhesion to Caco-2 cells was demonstrated by its ability to compete with, inhibit, and displace at rates of 54.10%, 48.80%, and 23.90%, respectively. The Lpb. pentosus SM1 exhibited broad-spectrum anti-microbial activity, particularly against Gram-positive bacteria, and inhibited biofilm formation. The strain also showcased antioxidant activity, effectively scavenging DPPH (57.60%) and ABTS (60.54%) radicals. Notably, it absorbed 51.60% of cholesterol, highlighting its potential for cholesterol-lowering benefits. The cytotoxicity values were measured at 36.57 mg/mL for HT-29 and 38.20 mg/mL for Hela cancer cell lines. Importantly, Lpb. pentosus SM1 was free of hemolytic activity and biogenic amines, demonstrating a favorable safety profile. Lpb. pentosus SM1 exhibited the strongest resistance to ampicillin, while its resistance to erythromycin was the weakest, with inhibition zones measuring 15.50 mm and 26.40 mm, respectively. These findings suggest that Lpb. pentosus SM1 has promising applications as a probiotic candidate for promoting gut health and preventing pathogenic infections.

A New Approach for Phage Cocktail Design in the Example of Anti-Mastitis Solution.

The studies on phage therapy have shown an overall protective effect of phages in bacterial infections, thus providing an optimistic outlook on the future benefits of phage-based technologies for treating bacterial diseases. However, the therapeutic effect is highly affected by the proper composition of phage cocktails. The rational approach to the design of bacteriophage cocktails, which is the subject of this study, allowed for development of an effective anti-mastitis solution, composed of virulent bacteriophages acting on Escherichia coli and Staphylococcus aureus. Based on the in-depth bioinformatic characterization of bacteriophages and their in vitro evaluation, the cocktail of five phages against E. coli and three against S. aureus strains was composed. Its testing in the milk model experiment revealed a reduction in the number of S. aureus of 45% and 30% for E. coli strains, and in the study of biofilm prevention, it demonstrated 99% inhibition of biofilm formation for all tested S. aureus strains and a minimum of 50% for 50% of E. coli strains. Such insights justify the need for rational design of cocktails for phage therapy and indicate the potential of the developed cocktail in the treatment of diseased animals, but this requires further investigations to evaluate its in vivo efficacy.

Synthesis and Application of Silver Nanoparticles for Caries Management: A Review.

Silver nanoparticles have unique physical, chemical, and biological properties that make them attractive for medical applications. They have gained attention in dentistry for their potential use in caries management. This study reviews the different synthesis methods of silver nanoparticles and the application of them for caries management. Silver nanoparticles are tiny silver and are typically less than 100 nanometres in size. They have a high surface area-to-volume ratio, making them highly reactive and allowing them to interact with bacteria and other materials at the molecular level. Silver nanoparticles have low toxicity and biocompatibility. Researchers have employed various methods to synthesise silver nanoparticles, including chemical, physical, and biological methods. By controlling the process, silver nanoparticles have defined sizes, shapes, and surface properties for wide use. Silver nanoparticles exhibit strong antibacterial properties, capable of inhibiting a broad range of bacteria, including antibiotic-resistant strains. They inhibit the growth of cariogenic bacteria, such as Streptococcus mutans. They can disrupt bacterial cell membranes, interfere with enzyme activity, and inhibit bacterial replication. Silver nanoparticles can inhibit biofilm formation, reducing the risk of caries development. Additionally, nano silver fluoride prevents dental caries by promoting tooth remineralisation. They can interact with the tooth structure and enhance the deposition of hydroxyapatite, aiding in repairing early-stage carious lesions. Silver nanoparticles can also be incorporated into dental restorative materials such as composite resins and glass ionomer cements. The incorporation can enhance the material's antibacterial properties, reducing the risk of secondary caries and improving the longevity of the restoration.

Assessment of the influence of synthetic peptide of the active center of granulocyte-macrophagal colony-stimulating factor – ZP2 on the growth properties of Corynebacterium spp.

The goal is to study the effect of the synthetic peptide of the active center of the granulocyte-macrophage coline-stimulating factor ZP2 on the growth properties and biofilm formation of microorganisms of the genus Corynebacterium spp. In vitro experiments were carried out on 13 isolates of Corynebacterium spp., including C. amycolatum (n = 7), C. propinquum (n = 2) and C. pseudodiphtheriticum (n = 4)), previously isolated from healthy individuals and are part of the Network Collection of Symbiotic Microorganisms and Their Consortia of the Institute for Cellular and Intracellular Symbiosis UrB RAS (Orenburg, Russia). The effect of different concentrations of the ZP2 peptide on the growth properties (planktonic culture growth and biofilm formation) of test strains was assessed in 96-well polystyrene plates. The inhibitory effect of the ZP2 peptide on the growth of planktonic culture was assessed by the Inhibition Index (%), on biofilm formation – by the Degree of Inhibition of Biofilm Formation (%). It was experimentally established that after 2, 4, 6 and 24 hours, a dose-dependent inhibition of the growth of planktonic cultures of all studied bacterial strains was observed under the influence of various concentrations of ZP2 (0.5-2.0 μg/ml). In this case, the inhibitory effect of the ZP2 peptide depended both on its concentration in the cultivation medium and on the growth phase of the test strain of bacteria. The maximum inhibition of the growth of planktonic culture of all studied bacterial strains under the influence of various concentrations of the ZP2 peptide was observed after 24 hours and ranged from 89.3±1.9 to 94.1±1.8% in C. amycolatum, and in C. propinquum from 90.0±0.6 to 96.7±0.3%, in C. pseudodiphtheriticum from 92.2±2.1 to 95.1±1.3. The ZP2 peptide also had a significant effect on biofilm formation in all test cultures studied. The reduction in biofilm formation depended on the concentration of the peptide and ranged from 62.4 to 78.4% in C. amycolatum, from 70.9 to 79.6% in C. propinquum, and from 76 to 82.7% in C. pseudodiphtheriticum. Thus, the antibacterial effect of the ZP2 peptide was revealed against the studied strains of corynebacteria species C. amycolatum, C. propinquum and C. pseudodiphtheriticum. According to available data, the ZP2 peptide is a drug with a wide spectrum of action that has an inhibitory effect not only on the studied actinobacteria, but also, according to literature data, on staphylococci and enterobacteria. An important prospect of the study is to reveal the mechanism of the antibacterial action of the ZP2 peptide with the characteristics of the effective concentration of the substance against pathogens and representatives of normal flora.

Porphyrinoid macrocycles as potential photosensitizers for photodynamic inhibition of biofilm formation in household water storage systems

AbstractThe issue of biofilm formation by microorganisms in household water storage systems is a problem that lowers the efficiency of disinfectants. Antimicrobial photodynamic inactivation (aPDI) is a potential alternative to the current water disinfection methods. It employs a photosensitizer agent that inactivates microbes by absorbing light of a specific wavelength in the presence of molecular oxygen. Although aPDI has been proven in literature to have a wide spectrum of action, effective against resistant microbes and biofilms, it has not been approved for real-life applications yet. Therefore, there is an ongoing search for ideal photosensitizers that can produce sufficient reactive oxygen species for efficient inactivation of microbes and disruption of biofilms in household water storage systems. This review summarises the developments that have been made so far with porphyrin-, expanded porphyrin-, corrole-, and boron dipyrromethene-based photosensitizers. First, the issues with the current water disinfection methods are described, and then aPDI is also described as a possible alternative to the current methods. Emphasis is put on the antimicrobial activities and the solid support materials that the porphyrinoid family members have been incorporated into for potential application in the disinfection of household water and limitation of biofilm formation in water storage systems.

Universal Receptive System as a novel regulator of transcriptomic activity of Staphylococcus aureus.

Our previous studies revealed the existence of a Universal Receptive System that regulates interactions between cells and their environment. This system is composed of DNA- and RNA-based Teazeled receptors (TezRs) found on the surface of prokaryotic and eukaryotic cells, as well as integrases and recombinases.. In the current study, we aimed to provide further insight into the regulatory role of TezR and its loss in Staphylococcus aureus gene transcription. To this end, transcriptomic analysis of S. aureus MSSA VT209 was performed following the destruction of TezRs. Bacterial RNA samples were extracted from nuclease-treated and untreated S. aureus MSSA VT209. After destruction of the DNA-based-, RNA-, or combined DNA- and RNA-based TezRs of S. aureus , 103, 150, and 93 genes were significantly differently expressed, respectively. The analysis revealed differential clustering of gene expression following the loss of different TezRs, highlighting individual cellular responses following the loss of DNA- and RNA-based TezRs. KEGG pathway gene enrichment analysis revealed that the most upregulated pathways following TezR inactivation included those related to energy metabolism, cell wall metabolism, and secretion systems. Some of the genetic pathways were related to the inhibition of biofilm formation and increased antibiotic resistance, and we confirmed this at the phenotypic level using in vitro studies. The results of this study add another line of evidence that the Universal Receptive System plays an important role in cell regulation, including cell responses to the environmental factors of clinically important pathogens, and that nucleic acid-based TezRs are functionally active parts of the extrabiome.

Coumarins: Quorum Sensing and Biofilm Formation Inhibition.

Quorum sensing (QS) is a bacterial cell-to-cell communication mechanism that plays an essential role in bacterial pathogenesis. QS governs bacterial behavior and controls biofilm formation, which in turn contributes to antibiotic resistance. Therefore, identifying and synthesizing novel compounds to overcome QS and inhibit biofilm formation are essential. Coumarins are important plant-derived natural products with wide-ranging bioactivities and extensive applications, including antibacterial, antifungal, anticoagulant, antioxidant, anticancer, and anti-inflammatory properties. Additionally, coumarins are capable of QS rewiring and biofilm formation inhibition, leading to higher susceptibility to antimicrobial agents and less antibiotic resistance. Therefore, in this review, we aim to provide an overview of QS and biofilm formation. This review also discusses the role of natural and synthesized coumarins in controlling QS, inhibiting biofilm formation, and inducing synergy in antibiotic-coumarin combinations. Hence, this review emphasizes the potential of coumarin compounds to act as antibacterial agents and demonstrates their ability to alleviate antibiotic resistance.

Combined potential of copaifera officinalis oleoresin and chitosan against oral pathogens.

Copaifera officinalis Oleoresin (COR) and Chitosan (CH) were combined to test the potential to inhibit oral bacteria. First, COR was analyzed by GC-MS to identify its main constituents and then Minimum Inhibitory Concentration (MIC) assays and Minimum Microbiocidal Concentration (MMC) of the compounds alone against 17 pathogens were performed. Sixteen primary compounds were identified in COR, but the major constituent was β-Caryophyllene (40.5%). COR showed MIC concentrations of 26.04 to 46.87µg/mL and CH 0.1mg/mL to 0.8mg/mL. Second, the combination against oral bacteria strains was tested using a checkerboard test with the determination of Fractional Inhibitory Concentration (FIC) for synergistic effect, followed by the bacterial biofilm aggregation test using monospecies and mixed biofilm. The combination of COR and CH showed a synergistic effect for S. oralis (ATCC 10557) and an additive effect for the other strains tested, promoting bactericidal activity, as well as reducing the concentrations needed to cause bacterial inhibition. In addition, it showed good activity in inhibiting biofilm formation, with inhibition percentages close to Azithromycin. The results of this study highlight the synergistic potential of COR and CH combination as a promising strategy in the search for innovative antimicrobial therapies for infections related to oral bacterial biofilms.

Evaluating the Efficacy of Actinidia deliciosa (Kiwi Fruit) Extract in Inhibiting Pseudomonas aeruginosa Biofilm Formation: An In Vitro Study With Therapeutic Implications.

Background Gram-negative Pseudomonas aeruginosa is a common bacteria that is well-known for its capacity to build biofilms, which are organized cell communities encased in a self-produced polymeric matrix. Treating infections becomes more challenging due to biofilms' capacity to provide immunity and resistance to antibiotics. The search for novel anti-biofilm agents has gained significant momentum, and the diverse range of bioactive compounds found in natural products offers a promising avenue. Rich in vitamins, antioxidants, and various phytochemicals, Actinidia deliciosa (kiwi fruit) has demonstrated potential as an antibacterial agent. Aim of the study This study aims to assess the efficacy of A. deliciosa extract in inhibiting biofilm formation by P. aeruginosa in vitro, providing valuable insights into its potential as a natural therapeutic agent for preventing recurrent bacterial infections. Materials and methodology The antibacterial and antibiofilm properties of A. deliciosa (kiwi fruit) methanolic extract were assessed in this study against P. aeruginosa (PAO1). The fruit was gathered, examined by a botanist for authenticity, and then cold macerated in methanol to create an extract. A two-fold broth dilution procedure was used to calculate the minimum inhibitory concentration (MIC), and agar well-diffusion was used to evaluate the antimicrobial activity. Pyocyanin pigment quantification was carried out after the extract was applied, and the antibiofilm impact was evaluated using a crystal violet assay. GraphPad Prism (GraphPad Software, San Diego, CA) was used for statistical analysis. Results Based on our findings, A. deliciosa was shown to have significant antibacterial and antibiofilm properties against P. aeruginosa (PAO1). At 5 mg/mL, the methanolic extract of A. deliciosa exhibited antibacterial activity with an 8 mm zone of inhibition and suppressed PAO1 growth. At 2.5 mg/mL and 1.25 mg/mL doses, PAO1 significantly decreased the production of biofilms by 60% and 29%, respectively. In addition, pyocyanin pigment synthesis was decreased by 30% and 9.25%, respectively, at sub-MIC doses of 2.5 mg/mL and 1.25 mg/mL. When evaluated at 2.5 mg/mL, the extract did not, however, appreciably affect bacterial growth. Conclusion This study enhances the understanding of antibiotic resistance, alternative treatments, and pathogenic microbes. The in vitro findings suggest that A. deliciosa fruit extract may inhibit pyocyanin production in PAO1. Further research with different formulations is recommended to explore its anti-biofilm properties and potential pharmacological applications.

Exploring Biosurfactants: Sustainable Solutions for Overcoming Antimicrobial Resistance and Drug Adverse Effects

Antimicrobial resistance (AMR) poses a significant global health threat, necessitating the exploration of alternative strategies to combat microbial pathogens. Biosurfactants, natural compounds produced by microorganisms, have emerged as promising candidates due to their diverse biological activities and sustainable properties. This review aims to provide a comprehensive overview of biosurfactants' potential as sustainable solutions for overcoming AMR and mitigating drug adverse effects. We discuss the mechanisms of action of biosurfactants against microbial pathogens, highlighting their ability to disrupt cell membranes, inhibit biofilm formation, and modulate immune responses. Furthermore, we explore the biocompatibility and eco-friendly nature of biosurfactants, underscoring their advantages over synthetic drugs. However, challenges such as limited scalability and variability in production hinder their widespread adoption in pharmaceutical applications. We propose interdisciplinary research efforts to address these challenges and optimize the use of biosurfactants in combating AMR and minimizing drug adverse effects. Through collaborative initiatives and innovative approaches, biosurfactants hold immense promise as sustainable alternatives to conventional antimicrobial agents, paving the way for a healthier and more resilient future.

Baicalin enhances antioxidant, inflammatory defense, and microbial diversity of yellow catfish (Pelteobagrus fulvidraco) infected with Aeromonas hydrophila.

The aim of this research was to clarify the mechanism through which baicalin exerts its inhibitory effects on Aeromonas hydrophila infection. The antibacterial efficacy of baicalin was assessed by determining its minimum inhibitory concentration (MIC) against A. hydrophila. Various parameters, including the growth curve, cell wall integrity, biofilm formation, AKP content, and morphological alterations of A. hydrophila, were analyzed. In vivo experiments involved the administration of A. hydrophila 4 h postintraperitoneal injection of varying doses of baicalin to induce infection, with subsequent monitoring of mortality rates. After a 3 d period, liver, spleen, and intestinal tissues were harvested to evaluate organ indices, antioxidant and immune parameters, as well as intestinal microbial composition. The findings indicated that baicalin treatment resulted in the disruption of the cell wall of A. hydrophila, leading to the loss of its normal structural integrity. Furthermore, baicalin significantly inhibited biofilm formation and facilitated the release of intracellular proteins (P < 0.05). In vivo, baicalin enhanced the survival rates of yellow catfish infected with A. hydrophila. Compared to the control group, the liver index of yellow catfish was elevated, while the spleen and intestinal indices were reduced in the baicalin-treated group (P < 0.05). Additionally, baicalin at an appropriate dosage was found to increase levels of SOD, GSH, CAT, ACP, and AKP in yellow catfish (P < 0.05), while simultaneously decreasing MDA accumulation and the mRNA expression of inflammatory markers such as Keap1, IL1, IFN-γ, and TNF-α, (P < 0.05). Moreover, baicalin significantly enhanced the operational taxonomic unit (OTU) count in A. hydrophila-infected yellow catfish (P < 0.05), restoring the abundance of Barnesiellaceae, Enterobacteriaceae, Plesiomonas, and UBA1819 (P < 0.05). In summary, baicalin demonstrates the potential to improve the survival rate of yellow catfish subjected to A. hydrophila infection, augment antioxidant and immune responses, mitigate inflammation, and enhance intestinal microbial diversity.

Polymyxin combined with Ocimum gratissimum essential oil: one alternative strategy for combating polymyxin-resistant Klebsiella pneumoniae.

Introduction. Multidrug-resistant infections present a critical public health due to scarce treatment options and high mortality. Ocimum gratissimum L. essential oil (O.geo) is a natural resource rich in eugenol known for its antimicrobial activity.Hypothesis/Gap Statement. O.geo may exert effective antimicrobial activity against polymyxin-resistant Klebsiella pneumoniae and, when combined with Polymyxin B (PMB), may exhibit a synergistic effect, enhancing treatment efficacy and reducing antimicrobial resistance.Aim. This study aims to investigate the antimicrobial activity of O.geo against polymyxin-resistant K. pneumoniae using in vitro tests and an in vivo Caenorhabditis elegans model.Methodology. The O.geo was obtained by hydrodistillation followed by gas chromatography. The MIC and antibiofilm activity were determined using broth microdilution. Checkerboard and time-kill assays evaluated the combination of O.geo and polymyxin B (PMB), whereas a protein leakage assay verified its action.Results. Eugenol (39.67%) was a major constituent identified. The MIC of the O.geo alone ranged from 128 to 512 µg ml-1. The fractional inhibitory concentration index (0.28) and time-kill assay showed a synergism. In addition, O.geo and PMB inhibited biofilm formation and increased protein leakage in the plasma membrane. The treatment was tested in vivo using a Caenorhabditis elegans model, and significantly increased survival without toxicity was observed.Conclusion. O.geo could be used as a potential therapeutic alternative to combat infections caused by multidrug-resistant bacteria, especially in combination with PMB.

Screening of the Pandemic Response Box library identified promising compound candidate drug combinations against extensively drug-resistant Acinetobacter baumannii

Infections caused by antimicrobial-resistant Acinetobacter baumannii pose a significant threat to human health, particularly in the context of hospital-acquired infections. As existing antibiotics lose efficacy against Acinetobacter isolates, there is an urgent need for the development of novel antimicrobial agents. In this study, we assessed 400 structurally diverse compounds from the Medicines for Malaria Pandemic Response Box for their activity against two clinical isolates of A. baumannii: A. baumannii 5075, known for its extensive drug resistance, and A. baumannii QS17-1084, obtained from an infected wound in a Thai patient. Among the compounds tested, seven from the Pathogen box exhibited inhibitory effects on the in vitro growth of A. baumannii isolates, with IC50s ≤ 48 µM for A. baumannii QS17-1084 and IC50s ≤ 17 µM for A. baumannii 5075. Notably, two of these compounds, MUT056399 and MMV1580854, shared chemical scaffolds resembling triclosan. Further investigations involving drug combinations identified five synergistic drug combinations, suggesting potential avenues for therapeutic development. The combination of MUT056399 and brilacidin against A. baumannii QS17-1084 and that of MUT056399 and eravacycline against A. baumannii 5075 showed bactericidal activity. These combinations significantly inhibited biofilm formation produced by both A. baumannii strains. Our findings highlight the drug combinations as promising candidates for further evaluation in murine wound infection models against multidrug-resistant A. baumannii. These compounds hold potential for addressing the critical need for effective antibiotics in the face of rising antimicrobial resistance.

Silver secnidazole nano-hybrid emulsion-based probiotics as a novel antifungal formula against multidrug-resistant vaginal pathogens.

This study presents a novel approach to manage vaginal infections due to Candidiasis, utilizing a novel silver secnidazole nano-hybrid emulsion (Ag-Secn-NHE)-based probiotics and free Ag-Secn-NHE. Ag-Secn-NHE was prepared by simple homogenization‒ultrasonication technique and validated by using a ultraviolet‒visible scan, dynamic light scattering, transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy, and zeta potential. Saccharomyces cerevisiae (RCMB 002Y001) is the most effective probiotic-producing organism that demonstrates significant effects when combined with Ag-Secn-NHE. Ag-Secn-NHE-based probiotics showed significant antifungal effect compared to free Ag-Secn-NHE, silver nitrate, silver nanoparticles, secnidazole, secnidazole nanoemulsion, and commercial vaginal wash against multidrug-resistant vaginal pathogens. The highest inhibitory effect was achieved with Ag-Secn-NHE-based probiotic against Candida auris, Candida albicans, and Cryptococcus neoformans with minimal inhibitory concentration (MIC) 0.625±0.002, 0.00625:1.25±0.012 and 0.00625:1.25±0.032mg/mL, respectively, in comparison with Ag-Secn-NHE that show MIC at 0.00625:1.25±0.612, 0.0125:2.5±0.812, and 0.0125:2.5±0.112mg/mL (Ag:Secn). Ag-Secn-NHE-based- probiotic show minimum fungicidal concentration (MFC) at range from 2.5 to 20mg/mL, wherever free Ag-Secn-NHE show MFC range from 5 to >20mg/mL. Additionally, Ag-Secn-NHE-based probiotics have 75% inhibition of biofilm formation against C. auris and 60% inhibition of biofilm formation against both Cryptococcus neoformans and C. albicans in comparison with free Ag-Secn-NHE. Time-kill curves showed that the antifungal effect of Ag-Secn-NHE-based probiotics was fungistatic at 2MIC value after 4h and after 16h for Ag-Secn-NHE. TEM photographs showed that C. auris cells treated with Ag-Secn-NHE-based probiotic formula revealed severe deformations and distored ultrastructural changes. furthermore, results indicated that the Gamma radiation up to 15kGy increases production of Ag-Secn-NHE in comparison with non-irradiated one.

Antibiofilm activity of truncated Staphylococcus aureus phenol soluble modulin α2 (SaΔ1Δ2PSMα2) against Candida auris in vitro and in an animal model of catheter-associated infection

Candida auris has emerged as a major multidrug-resistant nosocomial pathogen. The organism exhibits a persistent colonising phenotype, and causes recalcitrant infections often strongly linked to biofilm formation. Alternate strategies are urgently needed to combat this yeast and its biofilm-associated phenotype. This work aimed to evaluate the efficacy of select staphylococcal phenol soluble modulins (PSMs), namely, a truncated version of Staphylococcus aureus PSMα2 shortened by two amino acids at the N-terminal (SaΔ1Δ2PSMα2) and Staphylococcus epidermidis PSMδ against C. auris in vitro and in vivo. The antifungal and antibiofilm activity was tested by broth microdilution and XTT dye reduction assay. Combination effect with antifungal drugs was determined by fractional inhibitory concentration test. The efficacy of combination therapy using SaΔ1Δ2PSMα2 with amphotericin B or caspofungin was evaluated in murine model of C. auris catheter-associated infection. Based on antifungal activity, antibiofilm activity and cytotoxicity data, SaΔ1Δ2PSMα2 exhibited promising activity against C. auris biofilms. Nearly 50 % inhibition in biofilm formation was noted with 0.5–2 μM of the peptide against multiple clinical and C. auris colonizing isolates. It was synergistic with amphotericin B (ΣFIC = 0.281) and caspofungin (ΣFIC = 0.047) in vitro, and improved the activity of voriconazole in voriconazole-resistant C. auris. Combination therapy using amphotericin B or caspofungin (1 μg/ml) with SaΔ1Δ2PSMα2 resulted in 99.5 % reduction in C. auris biofilm in murine model, even when the peptide was used at a concentration that was neither fungicidal nor antibiofilm (0.125 μM; ≈0.26 μg/ml). The study provides insight into the potential utility of SaΔ1Δ2PSMα2-antifungal drug combination against C. auris biofilm-associated infections.

Design, synthesis, and molecular dynamic simulations of some novel benzo[d]thiazoles with anti-virulence activity against Pseudomonas aeruginosa

Inhibition of quorum sensing (QS) is an impending approach for targeting bacterial infection. Fourteen benzo[d]thiazole and 2-pyrazolo[1,5-a]pyrimidin-3-yl)benzo[d]thiazoles analogues were designed and synthesized as promising LasR antagonists with QS inhibition activity. Among the investigated compounds, compounds 3c, 3e, and 8d exhibited the highest percentage inhibition in biofilm formation (77 %, 63.9 %, 69.4 %), pyocyanin production (74.6 %, 64.9, 69.4 %), and rhamnolipids production (58.5 %, 51 %, 54.3 %) in P. aeruginosa, respectively. Additionally, compounds 3c, 3e and 8d achieved IC50 values against Las R equal 1.37 ± 0.35, 1.55 ± 0.24, 1.1 ± 0.15 μM respectively. Also, molecular docking of the target compounds into the LasR binding site co-crystalized “odDHL” revealed their binding with the essential residues for protein inhibition. Additionally, molecular dynamics simulation (MDS) experiments over 200 ns of compound 3c showed its ability to interact with the LasR binding site with dissociation of the protein's dimer confirming its action as a LasR antagonist. The obtained findings inspire further investigation for benzo[d]thiazole and 2-pyrazolo[1,5-a]pyrimidin-3-yl)benzo[d]thiazoles aiming to design and synthesize more potential QS inhibitors.

Characterization of Two Novel Endolysins from Bacteriophage PEF1 and Evaluation of Their Combined Effects on the Control of Enterococcus faecalis Planktonic and Biofilm Cells.

Endolysin, a bacteriophage-derived lytic enzyme, has emerged as a promising alternative antimicrobial agent against rising multidrug-resistant bacterial infections. Two novel endolysins LysPEF1-1 and LysPEF1-2 derived from Enterococcus phage PEF1 were cloned and overexpressed in Escherichia coli to test their antimicrobial efficacy against multidrug-resistant E. faecalis strains and their biofilms. LysPEF1-1 comprises an enzymatically active domain and a cell-wall-binding domain originating from the NLPC-P60 and SH3 superfamilies, while LysPEF1-2 contains a putative peptidoglycan recognition domain that belongs to the PGRP superfamily. LysPEF1-1 was active against 89.86% (62/69) of Enterococcus spp. tested, displaying a wider antibacterial spectrum than phage PEF1. Moreover, two endolysins demonstrated lytic activity against additional gram-positive and gram-negative species pretreated with chloroform. LysPEF1-1 showed higher activity against multidrug-resistant E. faecalis strain E5 than LysPEF1-2. The combination of two endolysins effectively reduced planktonic cells of E5 in broth and was more efficient at inhibiting biofilm formation and removing biofilm cells of E. faecalis JCM 7783T than used individually. Especially at 4 °C, they reduced viable biofilm cells by 4.5 log after 2 h of treatment on glass slide surfaces. The results suggest that two novel endolysins could be alternative antimicrobial agents for controlling E. faecalis infections.

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

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