Exploring the antibiofilm and toxicity of tin oxide nanoparticles: Insights from in vitro and in vivo investigations.

BACKGROUND INFORMATION: The advancement of biological-mediated nanoscience towards higher levels and novel benchmarks is readily apparent, owing to the use of non-toxic synthesis processes and the incorporation of various additional benefits. This study aimed to synthesize stable tin oxide nanoparticles (SnO2-NPs) using S. rhizophila as a mediator. METHODS: The nanoparticles that were created by biosynthesis was examined using several analytical techniques, including Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), UV-visible (UV-vis) spectroscopy, and energy dispersive X-ray spectroscopy (EDS). RESULTS: The results obtained from the characterization techniques suggest that S. rhizophila effectively catalyzed the reduction of SnCl2 to SnO2-NPs duration of 90 min at ambient temperature with the ƛmax of 328 nm. The size of the nano crystallite formations was measured to be 23 nm. The present study investigates nanoscale applications' antibacterial efficacy against four bacterial strains, including Klebsiella Sp, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The observed zone of inhibition for the nanoparticles (NPs) varied from 10 to 25 mm. The research findings demonstrate that the nanoparticles (NPs) are effective as antibacterial, phytotoxic, and cytotoxic agents.

Ascorbic acid potentiates photodynamic inactivation mediated by octyl gallate and blue light for rapid eradication of planktonic bacteria and biofilms.

This study reported for the first time that Ascorbic acid (AA) could appreciably boost the efficiency of Octyl gallate (OG)-mediated photodynamic inactivation (PDI) on Escherichia coli and Staphylococcus aureus in planktonic and biofilm states. The combination of OG (0.075 mM) and AA (200 mM) with 420 nm blue light (212 mW/cm2) led to a >6 Log killing within only 5 min for E. coli and S. aureus and rapid eradication of biofilms. The mechanism of action appears to be the generation of highly toxic hydroxyl radicals (•OH) via photochemical pathways. OG was exposed to BL irradiation to generate various reactive oxygen radicals (ROS) and the addition of AA could transform singlet oxygen (1O2) into hydrogen peroxide (H2O2), which could further react with AA to generate enormous •OH. These ROS jeopardized bacteria and biofilms by nonspecifically attacking various biomacromolecules. Overall, this PDI strategy provides a powerful microbiological decontamination modality to guarantee safe food products.

Antimicrobial resistance and carbapenemase dissemination in Pseudomonas aeruginosa isolates from Libyan hospitals: a call for surveillance and intervention.

Pseudomonas aeruginosa is a multidrug-resistant bacterium capable of forming biofilms. This study aimed to assess resistance of clinical isolates from Libyan hospitals to antipseudomonal antibiotics, the prevalence of selected extended-spectrum ß-lactamases and carbapenemase genes among these isolates, and the microorganisms' capacity for alginate and biofilm production. Forty-five isolates were collected from four hospitals in Benghazi and Derna, Libya. Antimicrobial susceptibility was determined using agar disc diffusion. The presence of resistance genes (blaCTXM, blaTEM, blaSHV-1, blaGES-1, blaKPC, and blaNDM) was screened using PCR. Biofilm formation was quantified via the crystal violet assay, while alginate production was measured spectrophotometrically. Resistance to antipseudomonal antibiotics ranged from 48.9% to 75.6%. The most prevalent resistance gene was blaNDM (26.7%), followed by blaGES-1 (17.8%). Moreover, all isolates demonstrated varying degrees of biofilm-forming ability and alginate production. No statistically significant correlation was found between biofilm formation and alginate production. The dissemination of resistant genes in P. aeruginosa, particularly carbapenemases, is of great concern. This issue is compounded by the bacteria's biofilm-forming capability. Urgent intervention and continuous surveillance are imperative to prevent further deterioration and the catastrophic spread of resistance among these formidable bacteria.

Antibacterial and antibiofilm activities of iodinated hydrocarbons against Vibrio parahaemolyticus and Staphylococcus aureus.

Food-related illnesses have become a growing public concern due to their considerable socioeconomic and medical impacts. Vibrio parahaemolyticus and Staphylococcus aureus have been implicated as causative organisms of food-related infections and poisoning, and both can form biofilms which confer antibiotic resistance. Hence, the need for continuous search for compounds with antibiofilm and antivirulence properties. In this study, 22 iodinated hydrocarbons were screened for their antibiofilm activity, and of these, iodopropynyl butylcarbamate (IPBC) was found to effectively control biofilm formation of both pathogens with a MIC of 50 µg/mL which was bactericidal to V. parahaemolyticus and S. aureus. Microscopic studies confirmed IPBC inhibits biofilm formation of both bacteria and also disrupted their mixed biofilm formation. Furthermore, IPBC suppressed virulence activities such as motility and hemolytic activity of V. parahaemolyticus and the cell surface hydrophobicity of S. aureus. It exhibited a preservative potential against both pathogens in a shrimp model. IPBC disrupted the cell membrane of S. aureus and V. parahaemolyticus and differentially affected gene expressions related to biofilm formation and virulence. Additionally, it displayed broad-spectrum antibiofilm activities against other clinically relevant pathogens. These findings indicate IPBC offers a potential means of controlling infections mediated by Vibrio and Staphylococcus biofilms.

Phytochemical screening of Podocarpus lambertii Klotzch ex Endl. leaf extracts and potential antimicrobial, antioxidant and antibiofilm activity.

Species of the genus Podocarpus L'Hér. ex Pers.present biological activities, such as analgesic, antioxidant, antifungal, acting in the fight against anemia, depurative and fortifying. Podocarpus lambertii Klotzch ex Endl. is a Brazilian native species popularly known as maritime pine and lacks information about its phytochemical profile and possible biological activities. The study was conducted to determine the phytochemical composition of soluble plant extracts of acetone (EA), ethyl acetate (EAE) and hexane (HE) from leaves of P. lambertii; evaluate the antimicrobial potential by the broth microdilution technique; antioxidant potential by the DPPH method, as well as to evaluate the biofilm inhibition capacity by the crystal violet assay and reduction of the yellow tetrazolium salt (MTT). Phytochemical screening detected the presence of flavonoids, triterpenoids, steroids, tannins, alkaloids and saponins. All extracts showed antimicrobial activity on the microorganisms tested, and the EA showed the best results. High free radical scavenging potential was observed only in EAE (96.35%). The antibiofilm potential was observed in the EAE extract. The results contribute to the knowledge of the species and indicate the potential of P. lambertii extracts as a source of plant bioactives for the development of new alternative strategies to control resistant microorganisms.

Antifungal and Antivirulence Activity of Vanillin and Tannic Acid Against Aspergillus fumigatus and Fusarium solani.

Aspergillus fumigatus and Fusarium solani infections have become severe health threat; both pathogens are considered a priority due to the increasing emergence of antifungal-resistant strains and high mortality rates. Therefore, the discovery of new therapeutic strategies has become crucial. In this study, we evaluated the antifungal and antivirulence effects of vanillin and tannic acid against Aspergillus fumigatus and Fusarium solani. The minimum inhibitory concentrations of the compounds were determined by the microdilution method in RPMI broth in 96-well microplates according to CLSI. Conidial germination, protease production, biofilm formation, and in vivo therapeutic efficacy assays were performed. The results demonstrated that vanillin and tannic acid had antifungal activity against Aspergillus fumigatus, while tannic acid only exhibited antifungal activity against Fusarium solani. We found that vanillin and tannic acid inhibited conidial germination and secreted protease production and biofilm formation of the fungal pathogens using sub-inhibitory concentrations. Besides, vanillin and tannic acid altered the fungal membrane permeability, and both compounds showed therapeutic effect against aspergillosis and fusariosis in an infection model in Galleria mellonella larvae. Our results highlight the antivirulence effect of vanillin and tannic acid against priority pathogenic fungi as a possible therapeutic alternative for human fungal infections.

Antibacterial effect and biocompatibility of silver nanoparticle-coated bone allograft substitutes.

Osteoinduction, and/or osteoconduction, and antibacterial characteristics are prerequisites for achieving successful bone grafting. This study aimed to coat bone allografts with silver nanoparticles and assess their antibacterial activity and biocompatibility compared to uncoated bone allografts. In this study, the bone allografts were coated with varying concentrations of silver nanoparticles (5 mg/l, 10 mg/l, and 50 mg/l) through a simple adsorption technique. Subsequently, the coated samples underwent characterization using SEM, FTIR, EDS, and XRD. The Minimal Inhibitory Concentration (MIC) of the silver nanoparticles was determined against Staphylococcus aureus and Streptococcus mutans. Bacterial growth inhibition was evaluated by measuring turbidity and performing a disk diffusion test. Moreover, qualitative investigation of biofilm formation on the coated bone allograft was conducted using SEM. Following this, MG-63 cell lines, resembling osteoblasts, were cultured on the bone allografts coated with 5 mg/l of silver nanoparticles, as well as on uncoated bone allografts, to assess biocompatibility. The MIC results demonstrated that silver nanoparticles exhibited antimicrobial effects on both microorganisms, inhibiting the growth of isolates at concentrations of 0.78 mg/L for Staphylococcus aureus and 0.39 mg/L for Streptococcus mutans. The bone allografts coated with varying concentrations of silver nanoparticles exhibited significant antibacterial activity against the tested bacteria, completely eradicating bacterial growth and preventing biofilm formation. The osteoblast-like MG-63 cells thrived on the bone allografts coated with 5 mg/l of silver nanoparticles, displaying no significant differences compared to both the uncoated bone allografts and the control group.  Within the limit of this study, it can be concluded that silver nanoparticles have a positive role in controlling graft infection. In addition, simple adsorption technique showed an effective method of coating without overwhelming the healing of the graft.

Targeting bacterial growth in biofilm conditions: rational design of novel inhibitors to mitigate clinical and food contamination using QSAR.

Antimicrobial resistance (AMR) is a pressing global issue exacerbated by the abuse of antibiotics and the formation of bacterial biofilms, which cause up to 80% of human bacterial infections. This study presents a computational strategy to address AMR by developing three novel quantitative structure-activity relationship (QSAR) models based on molecular topology to identify potential anti-biofilm and antibacterial agents. The models aim to determine the chemo-topological pattern of Gram (+) antibacterial, Gram (-) antibacterial, and biofilm formation inhibition activity. The models were applied to the virtual screening of a commercial chemical database, resulting in the selection of 58 compounds. Subsequent in vitro assays showed that three of these compounds exhibited the most promising antibacterial activity, with potential applications in enhancing food and medical device safety.

Phage-antibiotic combinations to control Pseudomonas aeruginosa-Candida two-species biofilms.

Phage-antibiotic combinations to treat bacterial infections are gaining increased attention due to the synergistic effects often observed when applying both components together. Most studies however focus on a single pathogen, although in many clinical cases multiple species are present at the site of infection. The aim of this study was to investigate the anti-biofilm activity of phage-antibiotic/antifungal combinations on single- and dual-species biofilms formed by P. aeruginosa and the fungal pathogen Candida albicans. The Pseudomonas phage Motto in combination with ciprofloxacin had significant anti-biofilm activity. We then compared biofilms formed by P. aeruginosa alone with the dual-species biofilms formed by bacteria and C. albicans. Here, we found that the phage together with the antifungal fluconazole was active against 6-h-old dual-species biofilms but showed only negligible activity against 24-h-old biofilms. This study lays the first foundation for potential therapeutic approaches to treat co-infections caused by bacteria and fungi using phage-antibiotic combinations.

Unveilling genetic profiles and correlations of biofilm-associated genes, quorum sensing, and antibiotic resistance in Staphylococcus aureus isolated from a Malaysian Teaching Hospital.

BACKGROUND: Staphylococcus aureus is a notorious multidrug resistant pathogen prevalent in healthcare facilities worldwide. Unveiling the mechanisms underlying biofilm formation, quorum sensing and antibiotic resistance can help in developing more effective therapy for S. aureus infection. There is a scarcity of literature addressing the genetic profiles and correlations of biofilm-associated genes, quorum sensing, and antibiotic resistance among S. aureus isolates from Malaysia. METHODS: Biofilm and slime production of 68 methicillin-susceptible S. aureus (MSSA) and 54 methicillin-resistant (MRSA) isolates were determined using a a plate-based crystal violet assay and Congo Red agar method, respectively. The minimum inhibitory concentration values against 14 antibiotics were determined using VITEK® AST-GP67 cards and interpreted according to CLSI-M100 guidelines. Genetic profiling of 11 S. aureus biofilm-associated genes and agr/sar quorum sensing genes was performed using single or multiplex polymerase chain reaction (PCR) assays. RESULTS: In this study, 75.9% (n = 41) of MRSA and 83.8% (n = 57) of MSSA isolates showed strong biofilm-forming capabilities. Intermediate slime production was detected in approximately 70% of the isolates. Compared to MSSA, significantly higher resistance of clindamycin, erythromycin, and fluoroquinolones was noted among the MRSA isolates. The presence of intracellular adhesion A (icaA) gene was detected in all S. aureus isolates. All MSSA isolates harbored the laminin-binding protein (eno) gene, while all MRSA isolates harbored intracellular adhesion D (icaD), clumping factors A and B (clfA and clfB) genes. The presence of agrI and elastin-binding protein (ebpS) genes was significantly associated with biofilm production in MSSA and MRSA isolates, respectively. In addition, agrI gene was also significantly correlated with oxacillin, cefoxitin, and fluoroquinolone resistance. CONCLUSIONS: The high prevalence of biofilm and slime production among MSSA and MRSA isolates correlates well with the detection of a high prevalence of biofilm-associated genes and agr quorum sensing system. A significant association of agrI gene was found with cefoxitin, oxacillin, and fluoroquinolone resistance. A more focused approach targeting biofilm-associated and quorum sensing genes is important in developing new surveillance and treatment strategies against S. aureus biofilm infection.

[Characteristics of drug resistance and biofilm formation in carbapenem-resistant Acinetobacter baumannii in hospitalized children]. / 住院患儿耐碳青霉烯类鲍曼不动杆菌的耐药及生物膜特征分析.

OBJECTIVES: To study the distribution, drug resistance, and biofilm characteristics of carbapenem-resistant Acinetobacter baumannii (CRAB) isolated from hospitalized children, providing a reference for the prevention and treatment of CRAB infections in hospitalized children. METHODS: Forty-eight CRAB strains isolated from January 2019 to December 2022 were classified into epidemic and sporadic strains using repetitive extragenic palindromic sequence-based polymerase chain reaction. The drug resistance, biofilm phenotypes, and gene carriage of these two types of strains were compared. RESULTS: Both the 22 epidemic strains and the 26 sporadic strains were producers of Class D carbapenemases or extended-spectrum ß-lactamases with downregulated outer membrane porins, harboring the VIM, OXA-23, and OXA-51 genes. The biofilm formation capability of the sporadic strains was stronger than that of the epidemic strains (P<0.05). Genes related to biofilm formation, including Bap, bfs, OmpA, CsuE, and intI1, were detected in both epidemic and sporadic strains, with a higher detection rate of the intI1 gene in epidemic strains (P<0.05). CONCLUSIONS: CRAB strains are colonized in the hospital, with sporadic strains having a stronger ability to form biofilms, suggesting the potential for forming new clonal transmissions in the hospital. Continuous monitoring of the epidemic trends of CRAB and early warning of the distribution of epidemic strains are necessary to reduce the risk of CRAB infections in hospitalized children.

Measurement and analysis of microbial fluoride resistance in dental biofilm models.

The interactions between communities of microorganisms inhabiting the dental biofilm is a major determinant of oral health. These biofilms are periodically exposed to high concentrations of fluoride, which is present in almost all oral healthcare products. The microbes resist fluoride through the action of membrane export proteins. This chapter describes the culture, growth and harvest conditions of model three-species dental biofilm comprised of cariogenic pathogens Streptococcus mutans and Candida albicans and the commensal bacterium Streptococcus gordonii. In order to examine the role of fluoride export by S. mutans in model biofilms, procedures for generating a strain of S. mutans with a genetic knockout of the fluoride exporter are described. We present a case study examining the effects of this mutant strain on the biofilm mass, acid production and mineral dissolution under exposure to low levels of fluoride. These general approaches can be applied to study the effects of any gene of interest in physiologically realistic multispecies oral biofilms.

Antimicrobial activity of essential oils against biofilms formed in dental acrylic resin: a systematic review of in vitro studies.

This study aimed to answer the question formulated according to the PICO strategy: 'Which essential oils show antimicrobial activity against biofilms formed on dental acrylic resin?' composed by population (dental acrylic resin), intervention (application of essential oils), comparison (denture cleansers, antifungal drugs, chlorhexidine, and oral mouthwashes), and outcome (antibiofilm activity). In vitro experimental studies evaluating the activity of EOs on biofilm formed on acrylic resin were included. PRISMA guidelines were followed, and the search was performed in the PubMed, Science Direct, Embase, and Lilacs databases and in the gray literature using Google Scholar and ProQuest in December 2023. A manual search of the reference lists of the included primary studies was performed. Of the 1467 articles identified, 37 were selected for full-text reading and 12 were included. Twelve EOs were evaluated, of which 11 showed activity against Candida spp., 3 against Staphylococcus aureus, and 1 against Pseudomonas aeruginosa. The EOs of Cymbopogon citratus, Cinnamomum zeylanicum, and Cymbopogon nardus showed higher action than chlorhexidine, C. nardus higher than Listerine, C. citratus higher than nystatin, and Melaleuca alternifolia higher than fluconazole and nystatin. However, chlorhexidine was more effective than Lippia sidoides and Salvia officinalis, sodium hypochlorite was more effective than L. sidoides, nystatin was more effective than Zingiber officinale, Amphotericin B more effective than Eucalyptus globulus and M. alternifolia. In conclusion, the EOs of C. zeylanicum, C. citratus, C. nardus, and M. alternifolia showed antimicrobial activity to reduce biofilm on dental acrylic resin.

New sensitive tools to characterize meta-metabolome response to short- and long-term cobalt exposure in dynamic river biofilm communities.

Untargeted metabolomics is a non-a priori analysis of biomolecules that characterizes the metabolome variations induced by short- and long-term exposures to stressors. Even if the metabolite annotation remains lacunar due to database gaps, the global metabolomic fingerprint allows for trend analyses of dose-response curves for hundreds of cellular metabolites. Analysis of dose/time-response curve trends (biphasic or monotonic) of untargeted metabolomic features would thus allow the use of all the chemical signals obtained in order to determine stress levels (defense or damage) in organisms. To develop this approach in a context of time-dependent microbial community changes, mature river biofilms were exposed for 1 month to four cobalt (Co) concentrations (from background concentration to 1 × 10-6 M) in an open system of artificial streams. The meta-metabolomic response of biofilms was compared against a multitude of biological parameters (including bioaccumulation, biomass, chlorophyll a content, composition and structure of prokaryotic and eukaryotic communities) monitored at set exposure times (from 1 h to 28 d). Cobalt exposure induced extremely rapid responses of the meta-metabolome, with time range inducing defense responses (TRIDeR) of around 10 s, and time range inducing damage responses (TRIDaR) of several hours. Even in biofilms whose structure had been altered by Co bioaccumulation (reduced biomass, chlorophyll a contents and changes in the composition and diversity of prokaryotic and eukaryotic communities), concentration range inducing defense responses (CRIDeR) with similar initiation thresholds (1.41 ± 0.77 × 10-10 M Co2+ added in the exposure medium) were set up at the meta-metabolome level at every time point. In contrast, the concentration range inducing damage responses (CRIDaR) initiation thresholds increased by 10 times in long-term Co exposed biofilms. The present study demonstrates that defense and damage responses of biofilm meta-metabolome exposed to Co are rapidly and sustainably impacted, even within tolerant and resistant microbial communities.

Lipopeptide biosurfactant as a potential root canal irrigation agent: Antimicrobial and anti-biofilm evaluation.

OBJECTIVES: Lipopeptide Biosurfactant (LB) is a bacteria derived compound able to reduce surface tension between water and hydrophobic substances and exhibit antimicrobial and anti-biofilm properties. This study aimed to investigate the antimicrobial and anti-biofilm effect of a Lipopeptide Biosurfactant (LB) on Enterococcus faecalis, and its potential use in root canal treatment, either as a standalone irrigation solution or in conjunction with sodium hypochlorite (NaOCl). METHODS: LB was extracted from Bacillus clausii isolate and the dry extract was diluted in deionized water. The antimicrobial effect of LB against planktonic E. faecalis was evaluated by determining the Minimal Inhibitory Concentration (MIC50). The anti-biofilm effect was evaluated by Minimal Biofilm Inhibitory Concentration (MBIC50) and Minimal Biofilm Eradication Concentration (MBEC50) assays on biofilm grown on dentin specimen surface. To evaluate the effectiveness of LB as a single irrigation solution and as a pre-irrigation prior to NaOCl, live and dead bacterial cells were quantified using Confocal Laser Scanning Microscopy (CLSM), and cell biomass was assessed. RESULTS: LB exhibited an MIC50 and MBIC50 of 100 ppm, with an MBEC50 of 1000 ppm, resulting in 52.94 % biofilm inhibition and 60.95 % biofilm eradication on dentin specimens. The effectiveness was concentration-dependent, at 500 ppm, LB demonstrated comparable antimicrobial efficacy to 2.5 % NaOCl. Pre-irrigation with LB resulted in lower biofilm biomass compared to NaOCl alone. CONCLUSION: Pre-irrigation with LB enhanced the antimicrobial effect when followed by NaOCl irrigation. Consequently, LB shows promise as both a standalone root canal irrigation solution and as an adjunct to NaOCl in root canal treatment. CLINICAL SIGNIFICANCE: The study highlights the potential of Lipopeptide Biosurfactant (LB) as an environmentally friendly irrigation solution for root canal treatment, demonstrating potent antimicrobial and anti-biofilm properties against Enterococcus faecalis. LB exhibits concentration-dependent efficacy comparable to 2.5 % NaOCl and can be used as a standalone irrigation solution or in conjunction with NaOCl.

Enhanced cavitation dose and reactive oxygen species production in microbubble-mediated sonodynamic therapy for inhibition of Escherichia coli and biofilm.

Sonodynamic therapy (SDT) is an emerging antibacterial therapy. This work selected hematoporphyrin monomethyl ether (HMME) as the sonosensitizer, and studied the enhanced inhibition effect of Escherichia coli and biofilm by microbubble-mediated cavitation in SDT. Firstly, the influence of microbubble-mediated cavitation effect on different concentrations of HMME (10 µg/ml, 30 µg/ml, 50 µg/ml) was studied. Using 1,3-diphenylisobenzofuran (DPBF) as an indicator, the effect of microbubble-mediated cavitation on the production of reactive oxygen species (ROS) was studied by absorption spectroscopy. Secondly, using agar medium, laser confocal microscopy and scanning electron microscopy, the effect of microbubble-mediated cavitation on the activity and morphology of bacteria was studied. Finally, the inhibitory effect of cavitation combined with SDT on biofilm was evaluated by laser confocal microscopy. The research results indicate that: (1) Microbubble-mediated ultrasound cavitation can significantly increase cavitation intensity and production of ROS. (2) Microbubble-mediated acoustic cavitation can alter the morphological structure of bacteria. (3) It can significantly enhance the inhibition of SDT on the activity of Escherichia coli and its biofilm. Compared with the control group, the addition of microbubbles resulted in an increase in the number of dead bacteria by 61.7 %, 71.6 %, and 76.2 %, respectively. The fluorescence intensity of the biofilm decreased by 27.1 %, 80.3 %, and 98.2 %, respectively. On the basis of adding microbubbles to ensure antibacterial and biofilm inhibition effects, this work studied the influence of cavitation effect in SDT on bacterial structure, providing a foundation for further revealing the intrinsic mechanism of SDT.

Meta-metabolomic responses of river biofilms to cobalt exposure and use of dose-response model trends as an indicator of effects.

The response of the meta-metabolome is rarely used to characterize the effects of contaminants on a whole community. Here, the meta-metabolomic fingerprints of biofilms were examined after 1, 3 and 7 days of exposure to five concentrations of cobalt (from background concentration to 1 × 10-5 M) in aquatic microcosms. The untargeted metabolomic data were processed using the DRomics tool to build dose-response models and to calculate benchmark-doses. This approach made it possible to use 100% of the chemical signal instead of being limited to the very few annotated metabolites (7%). These benchmark-doses were further aggregated into an empirical cumulative density function. A trend analysis of the untargeted meta-metabolomic feature dose-response curves after 7 days of exposure suggested the presence of a concentration range inducing defense responses between 1.7 × 10-9 and 2.7 × 10-6 M, and of a concentration range inducing damage responses from 2.7 × 10-6 M and above. This distinction was in good agreement with changes in the other biological parameters studied (biomass and chlorophyll content). This study demonstrated that the molecular defense and damage responses can be related to contaminant concentrations and represents a promising approach for environmental risk assessment of metals.

Biological activity of silver nanoparticles synthesized using viticultural waste.

This research paper presents a novel approach to the green synthesis of silver nanoparticles (AgNPs) using viticultural waste, allowing to obtain NP dispersions with distinct properties and morphologies (monodisperse and polydisperse AgNPs, referred to as mAgNPs and pAgNPs) and to compare their biological activities. Our synthesis method utilized the ethanolic extract of Vitis vinifera pruning residues, resulting in the production of mAgNPs and pAgNPs with average sizes of 12 ± 5 nm and 19 ± 14 nm, respectively. Both these AgNPs preparations demonstrated an exceptional stability in terms of size distribution, which was maintained for one year. Antimicrobial testing revealed that both types of AgNPs inhibited either the growth of planktonic cells or the metabolic activity of biofilm sessile cells in Gram-negative bacteria and yeasts. No comparable activity was found towards Gram-positives. Overall, pAgNPs exhibited a higher antimicrobial efficacy compared to their monodisperse counterparts, suggesting that their size and shape may provide a broader spectrum of interactions with target cells. Both AgNP preparations showed no cytotoxicity towards a human keratinocyte cell line. Furthermore, in vivo tests using a silkworm animal model indicated the biocompatibility of the phytosynthesized AgNPs, as they had no adverse effects on insect larvae viability. These findings emphasize the potential of targeted AgNPs synthesized from viticultural waste as environmentally friendly antimicrobial agents with minimal impact on higher organisms.

Application of cuminaldehyde and ciprofloxacin for the effective control of biofilm assembly of Pseudomonas aeruginosa: A combinatorial study.

Pseudomonas aeruginosa is widely associated with biofilm-mediated antibiotic resistant chronic and acute infections which constitute a persistent healthcare challenges. Addressing this threat requires exploration of novel therapeutic strategies involving the combination of natural compounds and conventional antibiotics. Hence, our study has focused on two compounds; cuminaldehyde and ciprofloxacin, which were strategically combined to target the biofilm challenge of P. aeruginosa. The minimum inhibitory concentration (MIC) of cuminaldehyde and ciprofloxacin was found to be 400 µg/mL and 0.4 µg/mL, respectively. Moreover, the fractional inhibitory concentration index (FICI = 0.62) indicated an additive interaction prevailed between cuminaldehyde and ciprofloxacin. Subsequently, sub-MIC doses of cuminaldehyde (25 µg/mL) and ciprofloxacin (0.05 µg/mL) were selected for an array of antibiofilm assays which confirmed their biofilm inhibitory potential without exhibiting any antimicrobial activity. Furthermore, selected doses of the mentioned compounds could manage biofilm on catheter surface by inhibiting and disintegrating existing biofilm. Additionally, the test combination of the mentioned compounds reduced virulence factors secretion, accumulated reactive oxygen species and increased cell-membrane permeability. Thus, the combination of cuminaldehyde and ciprofloxacin demonstrates potential in combating biofilm-associated Pseudomonal threats.

Host antimicrobial peptide S100A12 disrupts the fungal membrane by direct binding and inhibits growth and biofilm formation of Fusarium species.

Fungal keratitis is the foremost cause of corneal infections worldwide, of which Fusariumspp. is the common etiological agent that causes loss of vision and warrants surgical intervention. An increase in resistance to the available drugs along with severe side effects of the existing antifungals demands for new effective antimycotics. Here, we demonstrate that antimicrobial peptide S100A12 directly binds to the phospholipids of the fungal membrane, disrupts the structural integrity, and induces generation of reactive oxygen species in fungus. In addition, it inhibits biofilm formation by Fusariumspp. and exhibits antifungal property against Fusariumspp. both in vitro and in vivo. Taken together, our results delve into specific effect of S100A12 against Fusariumspp. with an aim to investigate new antifungal compounds to combat fungal keratitis.