Antibiofilm Activity Of Silver Nanoparticles Research Articles

Antibacterial and antibiofilm activity of silver nanoparticles stabilized with C-phycocyanin against drug-resistant Pseudomonas aeruginosa and Staphylococcus aureus.

Biofilms are bacterial communities that can protect them against external factors, including antibiotics. In this study, silver nanoparticles (AgNPs) were formed by modifying AgNPs with C-phycocyanin (Ag-Pc) to inhibit the growth of carbapenem-resistant Pseudomonas aeruginosa (CR P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) and destroy biofilm of these bacteria. The AgNPs were prepared with the green synthesis method, and Pc was used to stabilize the AgNPs. The Ag-Pc's antibacterial and antibiofilm effects were evaluated using the Microbroth dilution method and microtiter plate assay. The inhibitory effect of Ag-Pc on the expression of biofilm-related genes was evaluated by real-time PCR. Moreover, the MTT assay was used to assess the Ag-Pc toxicity. The Ag-Pc minimum inhibitory concentration (MIC) was 7.4μg/mL for CR P. aeruginosa and MRSA. Pc did not show antibacterial effects against any of the strains. Ag-Pc suppressed biofilm formation and destroyed matured biofilm in both bacteria more efficiently than the AgNPs (P< 0.05). The expression of all genes was not significantly reduced in the presence of synthesized nanoparticles. Finally, the MTT assay results did not show toxicity against a murine fibroblast cell line (L929) at MIC concentration. The present study showed the promising potential of Pc for improving the antibacterial and antibiofilm function of AgNPs and inhibiting drug-resistant bacteria. Therefore, Ag-Pc nanoparticles can be considered a promising therapeutic approach for the managing of the bacterial biofilm.

Antibiofilm Activity of Silver Nanoparticles Synthesized from Seed Extract of Garcinia Kola

Silver nanoparticles from plant extracts are novel compounds with potential antimicrobial properties. Studies on antibiofilm activity of Ag-NPs synthesized from seed extracts of Garcinnia kola (G. kola) were carried out. Garcinnia kola seed were obtained from Keffi market, Nigeria. Green synthesis of Ag-NPs from the seed was carried using 2.0mm silver-nitrate by use of standard method. The Ag-NPs synthesized from the seed were characterized using former transmission infrared (FITR) spectroscopy and scanning election microscope. The antimicrobial activity of the Ag-NPs against Klebsiella pneumonia (Kp) isolates were carried out using agar dilution method. The biofilm formation by the isolates as well as the inhibition and dissolution by Ag-NPs were eval__uated using microplate method. The functional groups detected in the Ag-NPs were N-H, C-O, N-O, and CΞC with peaks 906.5cm-1,1282.2cm-2, 13344cm-1, 1550.6cm-1 and 217.1cm-1 respectively. The size of the particles ranges from 179-296nm. The minimum inhibiting concentration (MICs) of the particles and meropenem against the isolates were 250µg/l and 4.0µg/l. The functional inhibiting concentrates of the particles were 1.0. The optical clarity of biofilm formed by the isolates was 2.073 and 2.049. the percentage biofilm inhibiting effects of the particles was highest apart. KpC (K. Pneumoniae ATCC BAA 1075) with percentage inhibit ranges from 27.28-21.67% at 80-12.5% of the MICs. The percentage inhibiting effect of Ag-NPs in with meropenem was highest at MICs but low in MIC 12.5 with percentage inhibition 28.26% and 27.18%. The Ag-NPs alone and antibacterial activity and biofilm inhibiting effect while Ag-NPs in with meropenem had effect but against isolate but with potential antibiofilm activity.

Synthesis and Antibiofilm Activity of Silver Nanoparticles Fabricated Sodium Alginate–Based Nanocomposite Film

Synthesis and Antibiofilm Activity of Silver Nanoparticles Fabricated Sodium Alginate–Based Nanocomposite Film

Green Synthesis and Antibiofilm Activity of Silver Nanoparticles by Camellia sinensis L. (White Tea Leaf)

Biosynthesis of nanoparticles refers to the production or synthesis of nanoparticles using organisms, such as bacteria, fungi, plants or their byproducts. This approach offers several advantages over conventional chemical methods, including eco-friendliness, cost-effectiveness, and potential for large-scale production. The silver nanoparticles (AgNPs) synthesized using aqueous Camellia sinensis L. (white tea leaf) extracts as reducing and stabilizing agents were reported and evaluated for antibiofilm activity against test microorganisms (Acinetobacter baumanii ATCC 19606 NRRLB 3704, Pseudomonas aeruginosa ATCC 27853 (Gram –), and Bacillus subtilis ATCC 6633, Staphylococcus haemolyticus ATCC 43252 (Gram +), and Candida albicans ATCC 10231) in the study. The synthesized AgNPs were observed and characterized using Uv-Vis spectroscopic analysis, scanning electron and transmission electron microscopy energy-dispersive spectra and Fourier transform infrared spectroscopy. The synthesized AgNP was also screened for antibiofilm activity against test microorganisms. Our results show that the synthesized AgNPs have the potential to be used for antibiofilm materials and different biomedical applications.

Antimicrobial Activity of Bovine Bone Scaffolds Impregnated with Silver Nanoparticles on New Delhi Metallo-β-Lactamase-Producing Gram-Negative Bacilli Biofilms

Introduction: The antibiofilm activity of silver nanoparticles has been extensively investigated in common bacteria. Metallo-β-lactamase-producing Gram-negative bacteria are hard-to-treat microorganisms with few therapeutic options, and silver nanoparticles were not evaluated on the biofilm of these bacteria. Objectives: The aim of this study was to evaluate the antibiofilm activity of a bone scaffold impregnated with silver nanoparticles in NDM-producing Gram-negative bacilli. Methods: Bone scaffolds from bovine femur were used for the tests and impregnated with silver nanoparticles (50 nm) by physical adsorption. Silver nitrate minimal inhibitory and bactericidal concentrations (MIC and MBC) were performed on NDM-producing Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Disc diffusion tests for silver nanoparticles’ susceptibility and the quantification of biofilm production on plate and bone with sessile cell count were performed. Results: The MIC results demonstrated that silver nitrate had an antimicrobial effect on all microorganisms, inactivating the growth of isolates from a concentration of 8 µg/mL. MBC results showed that E. coli 16.211 was the only isolate to present MIC that were different from MBC, with a value of 16 µg/mL. Conclusion: Bone scaffolds impregnated with silver nanoparticles can significantly reduce the biofilm of multidrug-resistant bacteria. This is a strategical material that can be used as bone implant in different clinical conditions.

Antimicrobial and anti-biofilm activity of silver nanoparticles biosynthesized with Cystoseira algae extracts

Antimicrobial resistance is an ever-growing global concern to public health with no clear or immediate solution. Silver nanoparticles (AgNPs) have long been proposed as efficient agents to fight the growing number of antibiotic-resistant strains. However, the synthesis of these particles is often linked to high costs and the use of toxic, hazardous chemicals, with environmental and health impact. In this study, we successfully produced AgNPs by green synthesis with the aid of the extract of two brown algae—Cystoseira baccata (CB) and Cystoseira tamariscifolia (CT)—and characterized their physico-chemical properties. The NPs produced in both cases (Ag@CB and Ag@CT) present similar sizes, with mean diameters of around 22 nm. The antioxidant activity of the extracts and the NPs was evaluated, with the extracts showing important antioxidant activity. The bacteriostatic and bactericidal properties of both Ag@CB and Ag@CT were tested and compared with gold NPs produced in the same algae extracts as previously reported. AgNPs demonstrated the strongest bacteriostatic and bactericidal properties, at concentrations as low as 2.16 µg/mL against Pseudomonas aeruginosa and Escherichia coli. Finally, the capacity of these samples to prevent the formation of biofilms characteristic of infections with a poorer outcome was assessed, obtaining similar results. This work points towards an alternative for the treatment of bacterial infections, even biofilm-inducing, with the possibility of minimizing the risk of drug resistance, albeit the necessary caution implied using metallic NPs.Graphical abstract

Enhancement of anti-bactericidal and anti-biofilm activities of silver nanoparticles against multidrug-resistant enteric pathogens isolated from children with diarrhea

Background: Gastroenteritis has a significant mortality andmorbidity incidence in children globally. Antimicrobial resistance in Enterobacteriaceaeis a serious public health problem, especially in developing countries.Objective: The present study aimed to evaluate the anti-bacterial and anti-biofilmactivities of AgNPs alone and in combination with kanamycin against multidrug-resistant Enterobacteriaceae and P. aeruginosa isolated from diarrheal children.Materials and methods: 90 Enterobacteriaceae and P. aeruginosa isolates fromdiarrheal children were evaluated against 10 antibiotics. Minimum inhibitory doses ofAgNPs and kanamycin were determined using broth microdilution, synergistic wasdetermined using Checkerboard dilution tests, and the Calgary technique was used toanalyze biofilm development.Results: A total of 90 stool cultures were conducted for bacteria associated withdiarrhea among children attending some Baghdad hospitals. The findings revealed thatbacterial diarrhea was most often caused by E. coli 31 (34.5%), followed by S. typhi 19(21.1%), K. pneumoniae 14 (15.5%), P. aeruginosa 11 (12.2%) and S. sonnei 6 (6.7%),and significant variations between the strain&amp;#39;s species were discovered using statisticalanalysis (P &amp;lt; 0.05). The present study&amp;#39;s findings revealed that bacteria isolated fromchildren with diarrhea were spread significantly in age groups of 37–48 months andsignificantly different between age groups (P &amp;lt; 0.05), with a male/female ratio of0.57/1. Imipenem and amikacin were the most active antibiotics compared to penicillin,which was the least effective antibiotic. The combination of sublethal doses of AgNPswith sub-MIC (½MIC) of kanamycin exhibited substantial synergistic bactericidaleffects against MDR-Enterobacteriaceae. AgNPs inhibited biofilm formation by55%–65% for diarrhea-causing bacteria, while the combination of AgNPs withkanamycin demonstrated the strongest biofilm inhibition of around 80%–90% againstMDR-Enterobacteriaceae with a highly significant variation (P &amp;lt; 0.05).Conclusions: The outcomes of the research shows that the combination of AgNPs withkanamycin has remarkable synergistic bactericidal and anti-biofilm effectivenessagainst MDR-Enterobacteriaceae isolated from diarrheal children.

Antimicrobial and antibiofilm activity of silver nanoparticles against Salmonella Enteritidis.

Salmonella enterica serotype Enteritidis is one of the main pathogens associated with foodborne illnesses worldwide. Biofilm formation plays a significant role in the persistence of pathogens in food production environments. Owing to an increase in antimicrobial resistance, there is a growing need to identify alternative methods to control pathogenic microorganisms in poultry environments. Thus, this study aimed to synthesize silver nanoparticles (AgNPs) and evaluate their antibiofilm activity against poultry-origin Salmonella Enteritidis in comparison to a chemical disinfectant. AgNPs were synthesized, characterized, and tested for their minimum inhibitory concentration, minimum bactericidal concentration, and antibiofilm activity against S. Enteritidis strains on polyethylene surfaces. The synthesized AgNPs, dispersed in a liquid medium, were spherical in shape with a mean diameter of 6.2nm. AgNPs exhibited concentration-dependent bactericidal action. The bacterial reduction was significantly higher with AgNPs (3.91 log10 CFU [Formula: see text] cm-2) than that with sanitizer (2.57 log10 CFU∙cm-2). Regarding the time of contact, the bacterial count after a contact time of 30min was significantly lower than that after 10min. The AgNPs exhibited antimicrobial and antibiofilm activity for the removal of biofilms produced by S. Enteritidis, demonstrating its potential as an alternative antimicrobial agent. The bactericidal mechanisms of AgNPs are complex; hence, the risk of bacterial resistance is minimal, making nanoparticles a potential alternative for microbial control in the poultry chain.

P013 Green synthesis of silver nanoparticles using Trillium govanianum and its antifungal potential against Candida auris

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM ObjectiveThis study aimed to evaluate the antifungal and anti-biofilm activities of silver nanoparticles synthesized using Trillium govanianum, a trans-Himalayan medicinal plant extract, against multidrug-resistant Candida auris.MethodsSilver nanoparticles (AgNPs) were synthesized by adopting a green approach. Optimization and characterization of TG-AgNPs were carried out using UV-VIS spectroscopy, TEM, and FTIR. Minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and antibiofilm activity of the crude extract, as well as TG-nanoparticles, were evaluated. Furthermore, their effect on cell morphology and cell permeability was also analyzed using FESEM.ResultsCrude extracts of roots of T. govanianum exerted remarkable antifungal activity against multiple strains of Candida auris. The incorporation of silver nanoparticles to plant extract significantly improved the antifungal and antibiofilm activities against the tested strains in a synergistic manner.ConclusionSilver nanoparticles synthesized using Trillium govanianum extract provide eco-friendly, biocompatible nanostructures with antifungal activity and have the potential for use as a therapeutic/nutraceutical agent.

Antibiofilm activity of silver nanoparticles biosynthesized using viticultural waste.

Green methods have become vital for sustainable development of the scientific and commercial sphere; however, they can bring new challenges, including the need for detailed characterization and elucidation of efficacy of their products. In this study, green method of silver nanoparticles (AgNPs) production was employed using an extract from grapevine canes. The aim of the study was to contribute to the knowledge about biosynthesized AgNPs by focusing on elucidation of their antifungal efficiency based on their size and/or hypothesized synergy with bioactive substances from Vitis vinifera cane extract. The antifungal activity of AgNPs capped and stabilized with bioactive compounds was tested against the opportunistic pathogenic yeast Candida albicans. Two dispersions of nanoparticles with different morphology (characterized by SEM-in-STEM, DLS, UV-Vis, XRD, and AAS) were prepared by modification of reaction conditions suitable for economical production and their long-term stability monitored for six months was confirmed. The aims of the study included the comparison of the antifungal effect against suspension cells and biofilm of small monodisperse AgNPs with narrow size distribution and large polydisperse AgNPs. The hypothesis of synergistic interaction of biologically active molecules from V. vinifera extracts and AgNPs against both cell forms were tested. The interactions of all AgNPs dispersions with the cell surface and changes in cell morphology were imaged using SEM. All variants of AgNPs dispersions were found to be active against suspension and biofilm cells of C. albicans; nevertheless, surprisingly, larger polydisperse AgNPs were found to be more effective. Synergistic action of nanoparticles with biologically active extract compounds was proven for biofilm cells (MBIC80 20 mg/L of polydisperse AgNPs in extract), while isolated nanoparticles suspended in water were more active against suspension cells (MIC 20 mg/L of polydisperse AgNPs dispersed in water). Our results bring new insight into the economical production of AgNPs with defined characteristics, which were proven to target a specific mode of growth of significant pathogen C. albicans.

Antibacterial and Antibiofilm Activity of Silver Nanoparticles Synthesised by Beetroot Containing Betalains Pigment on Clinical Bacterial Isolates

Introduction: Artificial colours have been used in foods for many years with adverse side effects. As a result, many studies have focused on natural dyes, and interest in natural dyes is increasing every day due to the lack of side effects. The betalains are pigments, which are present in the Beta vulgaris L (red beet) roots; these are exploited for native colouring and additive agents in food. These compounds possess many desirable properties such as antioxidant and antimicrobial activity etc., Nanotechnology is currently being used to enhance plant medicinal applications. It is an environmentally non toxic and low cost method. Aim: To examine the role of beetroot containing betalain on synthesising silver nanoparticles (AgNPs) and determine the antibacterial activity. Materials and Methods: This in-vitro study was carried in Department of Botany, KK College in Namakkal, Tamilnadu during the period of December, 2018 to December, 2020. The 2mM of AgNPs was utilised for the preparation of nanoparticles with beetroot containing betalains. The characterisation of synthesised AgNPs was done by Fourier Transform Infrared spectroscopy (FTIR), Ultraviolet-Visible (UV-Vis) spectroscopy, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). In addition, the antibacterial activity of AgNPs was evaluated by the agar well-diffusion method. Results: In this study, the highest concentration of betalains observed at pH 5 in both solvents [ethanol (154.4 mg/100 mg) and water (131.2±0.15/100 mg)] was recorded. The acetone recorded a maximum of 143.8 mg/100 mg at pH 4. Bio sourced AgNPs had antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Proteus sp, Salmonella sp and Acinetobacter baumannii. Furthermore, synthesised AgNPs inhibited the biofilm formation in all isolates. Conclusion: This study reveals that AgNPs exhibit strong antimicrobial activity so that they can be developed as new types of antimicrobial agents to treat bacterial infections, including biofilm bacterial infections, and are attractive and environmentally friendly.

Antibacterial and anti-biofilm activity of silver nanoparticles on multi-drug resistance pseudomonas aeruginosa isolated from dental-implant

AimThe aim of this study was to isolate multi-drug-resistant p. aeruginosa from dental implant, and control the growth and biofilm of isolated p. aeruginosa by silver nanoparticles. Materials and methodsThirty specimens from patients with Peri-implantitis were taken for isolation of p. aeruginosa. Bacterial samples were obtained from the infected peri-implant pocket with sterile paper points (size 30–45 mm). Samples were cultured for isolation of Multi-drug resistance P. aeruginosa. Phenotypical identification was done by the VITEK 2 system. DNA was extracted from the isolates and 16S rDNA-based PCR assay was used to confirm the identification. Susceptibility of isolated p. aeruginosa to 16 antibiotics was evaluated using the VITEK 2 system. The growth inhibition of isolated bacteria by AgNPs was tested by disk-diffusion method. The microtiter plate assay was used to estimate the capacity of P. aeruginosa to from biofilms. Antibiofilm activity of AgNPs was determined by microtiter plate assay. ResultsThree P. aeruginosa were successfully isolated from 30 clinical specimens. P. aeruginoas isolates were resistance to most of used antibiotics. Silver nanoparticles exerted an inhibitory effect on all isolated bacteria. All tested concentration of AgNPS exhibited a greatest anti-biofilm activity against multi-drug resistance (MDR) p. aeruginosa. ConclusionCurrent findings highlight the role of AgNPS in growth inhibition of P. aeruginosa and reveal a potential application of AgNPS in eradication of p. aeruginosa biofilms.

Antimicrobial and Antibiofilm Effects of Silver Nanoparticles Produced byYarrowia lipolyticaAgainst Vegetative and StarvedShigella

Silver nanoparticles have attracted much interest from scientists to develop nanosilver-based disinfectant products due to their unique properties of high antimicrobial activity. This study focused on biosynthesis, characterization, antimicrobial and antibiofilm effects of silver nanoparticles against vegetative and starved Shigella strains. The silver nanoparticles were synthesized using the yeast Yarrowia lipolytica and characterized by ultraviolet–visible spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The antimicrobial and antibiofilm activities of silver nanoparticles were tested against the growth of vegetative and starved Shigella strains. After the addition of silver nitrate solution to the supernatant of Y. lipolytica, we noticed the appearance of a brown-black coloration that suggested the formation of silver nanoparticles. The presence of silver nanoparticles was manifested by a maximum absorption in the ultraviolet–visible range, precisely at the wavelength 420[Formula: see text]nm. The crystalline nature and the stability of silver nanoparticles were confirmed, respectively, by XRD and FTIR analysis. The antibacterial activity of silver nanoparticles showed significant toxicity on Shigella strains indicating that the starved cells were more sensitive to treatment with silver nanoparticles than vegetative cells. Surprisingly, the biofilm formation had not been inhibited by silver nanoparticles for both vegetative and starved cells. In conclusion, a new class of nanosilver containing disinfectant nanoproducts will be promising for advanced environmental treatments including air disinfection, water disinfection, surface disinfection and personal hygiene that will help to prevent the further outbreak of diseases.

Antibiofilm activity of silver nanoparticles against biofilm forming Staphylococcus pseudintermedius isolated from dogs with otitis externa.

BackgroundSilver nanoparticles (AgNPs) are known to possess antimicrobial properties. Although the antibiofilm activity of AgNPs has been demonstrated in humans, this activity has not yet been elucidated in veterinary medicine.ObjectivesThe purpose of this study was to evaluate the antibiofilm activity of silver nanoparticles against Staphylococcus pseudintermedius.MethodsTen isolates of S. pseudintermedius obtained from dogs with otitis externa were treated with AgNPs, and the antibiofilm activity was measured using a modified microtiter plate and Congo red agar (CRA) method and scanning electron microscopy.ResultsAgNPs displayed a significant dose‐dependent antibiofilm activity and reduced biofilm formation at concentrations of 20 and 10 µg/ml (p < 0.05). S. pseudintermedius exposed to 20 µg/ml of AgNPs formed less bacterial slime compared to the controls on CRA plates. Scanning electron micrographs showed that the biofilm had few individually scattered cells along its surface when treated with AgNP concentrations of 20 and 10 µg/ml. Untreated surfaces showed an aggregated biofilm.ConclusionsOur results suggested that AgNP may be a valuable alternative antibiofilm agent for canine otitis externa.

Antibacterial, Antifungal and Antibiofilm Activities of Silver Nanoparticles Supported by Crude Bioactive Metabolites of Bionanofactories Isolated from Lake Mariout.

Lake Mariout is one of the polluted coastal marine ecosystems in Egypt which is considered to be a reservoir of serious effluents from different anthropogenic activities. Such selective pressure enforces indigenous microbial populations to acquire new advantageous themes. Thus, in this study, two Streptomyces strains were screened, from Lake Mariout’s sediment for bioreduction of 5 mM AgNO3. Both strains were identified molecularly; their biochemical and physiological characterization revealed their ability to secrete bioactive metabolites with antagonistic activity. The cultural and incubation conditions influencing AgNPs productivity were evaluated. Subsequently, the physicochemical properties of the biofabricated AgNPs were pursued. UV-Vis spectroscopy detected surface plasmon resonance at range 458–422 nm. XRD indicated crystalline, pure, face-centered cubic AgNPs; EDX demonstrated strong silver signal at 3.5 keV. Besides, FT-IR and TGA analysis unveiled self-stabilization and functionalization of AgNPs by bioorganic molecules. However, electron microscopy micrographs depicted numerous uniform spherical AgNPs (1.17–13.3 nm). Potent bactericidal and fungicide activity were recorded by zone of inhibition assay at 50 μg/mL. Further, the antibiofilm activity was exerted in a dose-dependent manner. Moreover, the conjugation of AgNPs with the crude bioactive metabolites of both bionanofactories ameliorated the antimicrobial potency, reflecting a synergistic efficiency versus examined pathogens (free-living and biofilm).

Silver nanoparticles: A potential antibacterial and antibiofilm agent against biofilm forming multidrug resistant bacteria

Multi-drug resistant (MDR) bacteria are seriously endangering the antibiotics. Different alternative strategies are needed to reinforce antibiotics, of, these; nanostructured materials may play a fruitful role. This study aimed to investigate the antibacterial and antibiofilm activity of silver nanoparticles (AgNPs) against MDR bacteria. Methods: In a cross-sectional study, a total of 33 methicillin resistant Staphylococcus aureus (MRSA) and 52 MDR Pseudomonas aeruginosa (P. aeruginosa) isolates were recovered from intensive care units’ (ICUs) admitted patients over a period of 9 months, from December 2017 to August 2018. The antibacterial activity of AgNPs on the clinical isolates of MRSA and MDR P. aeruginosa was assessed by minimum inhibitory concentrations (MICs) using broth microdilution method. The minimum bactericidal concentrations (MBCs) were determined as the lowest concentrations required to kill 99.9% of the initial inoculum. Tissue culture plate method was used to evaluate the antibiofilm activity. Results: The MIC and MBC values ranged from 1 to 16 μg/ml and 2 to 64 μg/ml, respectively. Silver nanoparticles exerted a significant antibiofilm activity against MRSA and MDR P.aeruginosa at all tested concentrations, recording a maximum inhibition value of (82%) and (91%), respectively. Conclusions: AgNPs exhibited a considerable antibacterial and antibiofilm, effect; it could represent a promising weapon in the fight against biofilm forming MDR organisms.

Inhibitory Activity of Silver Nanoparticles Synthesized Using Lycopersicon Esculentum against Biofilm Formation in Candida Species.

This paper investigated the antifungal and antibiofilm activity of silver nanoparticles synthesized with Lycopersicon esculentum extracts against Candida species. Lycopersicon esculentum extracts obtained by homogenization were mixed with silver nitrate to synthesize silver nanoparticles. Analysis of the particle characteristics by UV–Vis spectrophotometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FT-IR) confirmed that the Lycopersicon esculentum extracts effectively served as reductants and capping agents. Minimum inhibitory concentration (MIC) tests were conducted to confirm antifungal activity against Candida species. In all the tested species, the silver nanoparticles inhibited the growth of Candida. Moreover, the SEM images of Candida species treated with silver nanoparticles synthesized using natural extracts of Lycopersicon esculentum showed that silver nanoparticles adhered to the surface of Candida, which induced pore formation in the membranes and prevented their normal growth. Ultimately, these abnormal forms of Candida were thought to be less able to form biofilms than normal Candida. The antifungal and antibiofilm activities of silver nanoparticles against Candida are expected to be utilized in various fields and contribute in particular to developments in nanomedicine.

Simultaneous Antibacterial and Antibiofilm Activities of three Types of Silver Nanoparticles against Human Bacterial Pathogens.

Emergence of antibiotic resistant bacteria result in an approximately 550,000 deaths from bacterial infections annually. Several studies reported interesting antibacterial and anti-biofilm activities of silver nanoparticles synthesized by different physical, chemical and biological methods as an alternative to antibiotics. However, the resultant nanoparticles were varying in size, shape, and had different antibacterial and antibiofilm activities with different concentrations. Moreover, previous studies had investigated the antibacterial and antibiofilm activities in separate protocols and didn’t investigate the real-time or dual effect of silver nanoparticles on both planktonic and sessile cells within single protocol. This study aimed to synthesize silver nanoparticles through three methods and analyzing the simultaneous antibacterial and antibiofilm activities against planktonic and sessile bacterial cells. Three methods were applied to analyze silver nanoparticles and used to investigate the dual effect against bacterial biomass and biofilm formation. The results showed that synthesized silver nanoparticles cause significant inhibition to bacterial cell biomass and bacterial biofilm formation when compared with controls at low concentration. Significant Higher antibiofilm activity than antibacterial activity was observed at very low concentration (0.0125 µg/ ml). The antibacterial and antibiofilm activity do not differ according to the type of bacteria. Whereas, the antibacterial effect differs significantly according to the methods of silver nanoparticles synthesis.

The Inhibitory Effects of Silver Nanoparticles on Bap Gene Expression in Antibiotic-Resistant Acientobacter bumanni Isolates using Real-Time PCR

Introduction: Acinetobacter bomanni is one of the most common opportunistic pathogens in hospitals that are resistant to many antibiotics due to biofilm production. Nowadays, silver nanoparticles(AgNPs) have received wide attention in medicine due to their physical and chemical properties. This study aimed to evaluate the anti-biofilm activity of silver nanoparticles on antibiotic-resistant A. bumanni strains. Materials & Methods: In this experimental study, A. bumanni was isolates from 100 clinical samples. After identification of A. bummani strains and determination of antibiotic resistant profiles, biofilm-producing isolates were determined using Congo red agar at 37°C after 24 hours. The minimum inhibitory concentration (MIC) of the strains against AgNPs was determined. After 24 hours of exposure of the strains to sub-MIC concentration of AgNPs, RNA extraction and cDNA synthesis were performed. Finally, Bap gene expression was measured using real time PCR method. Finding: Out of 100 clinical isolates, 12 belonged to A. bummani, and all the strains were resistant to antibiotics, except for colistin. Real-time PCR results show that all the strains had a significant down-regulation in Bap gene expression compared to the control gene (P less-than 0.05). Discussion & Conclusions: According to the anti-biofilm effects of AgNPs, it seems that AgNPs can be used as drug candidates in pharmaceutical industries.

Evaluation of bactericidal and anti-biofilm activities of silver nanoparticles against multidrug-resistant Gram-negative bacilli isolated from burn wound infections

Background: The emergence and spread of multidrug-resistant Gram-negative bacilliin burn wound infections related to biofilm formation, which lend to challenge in treatment with conventional antibiotics andprompting to search for novel antimicrobial agents to control the infections.Silver nanoparticles (AgNPs) have wide spectrum biological properties with different mechanisms of action and less toxicity towards human cells.&#x0D; Objective:The goal of this study was to evaluated the anti-bacterial and anti-biofilm activities of AgNPs alone and in combination with aminoglycoside (Amikacin) and β-lactam (Ampicillin) antibiotics against multidrug resistant Gram-negative bacilli (Pseudomonas aeruginosa, Escherichia coli, klebsiellapneumoniae) isolated from burn wound infections. Type of the study: Cross –sectional study.&#x0D; Methods: 70 clinical isolates of GNBtested for susceptibility tests by disk diffusion method against 10 antibiotics. The minimum inhibitory concentrations (MICs) of AgNPs and antibiotics were carried out according to the standard broth microdilution method, while synergistic interactions were evaluated by time kill-kinetic assays. Calgary method was applied for anti-biofilm activity.&#x0D; Results:Pseudomonas aeruginosa represented the majority of GNBisolated from burn wound infections 34 (48.5 %)followed by Klebsiella pneumonia 21 (30 %) and Escherichia coli 15 (21.5 %). Silver nanoparticles showed remarkable antibacterial activity against GNB that isolated from burn wound infections with the MICs between 25- 75 µg/ml. Aztreonam, amikacin and cefepime were the most effective antimicrobial drugagainst GNB isolates.Synergistic bactericidal effects were observed in two-drug combinations of AgNPswith broad-spectrum aminoglycoside (Amikacin) and β-lactam (Ampicillin) antibiotics against multidrug resistant GNB. In addition,AgNPsalone or in combination with ampicillin inhibited biofilm activity about 60 % – 75 % ofGNB,while combination of AgNPs withamikacin exhibited a powerful anti-biofilm activity and inhibition biofilm formation by 75% to 80%.&#x0D; Conclusion: The results confirmed a synergistic bactericidal effects and significant enhancing of anti-biofilm activity of AgNPs in combination with antibiotics (amikacin and ampicillin) against multidrug resistant GNB isolated from burn wound infections. These data suggest that AgNPs could beapplied as nanodrug for treatment of burn wound infections