Gram-negative Strains Research Articles

Bio-based polylactic acid labware as a sustainable alternative for microbial cultivation in life science laboratories

Single-use plastics (SUPs) in life science laboratories account for approximately 5.5 million tonnes of waste per year globally. Of SUPs used in life science laboratories, Petri dishes, centrifuge tubes, and inoculation loops are some of the most common. In order to reduce the reliance on petrochemical-based SUPs in the life science research laboratory and minimize the negative environmental impacts associated with SUPs, this research investigates the applicability of polylactic acid (PLA) in single-use labware as a replacement for petrochemical-based plastics. PLA is one of the most well-studied biodegradable plastics that can be produced from sustainable resources. Commercially available PLA was used to 3D print a select range of labware to test the suitability of PLA-based material for routine microbiology work. An injection moulded PLA-based Petri dish was also designed and produced, for increased optical clarity. The biocompatibility was tested against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) strains of bacteria. The PLA-based labware did not negatively impact the cell growth, viability, and metabolic activity of the bacterial cultures. The injection moulded PLA Petri dish showed a reduced colony forming unit count for the Gram-negative E. coli strain compared to the polystyrene Petri dish, ∼1.5 × 109 CFU/mL and ∼3.0 × 109 CFU/mL respectively, during late-exponential growth. The colony counts were, however, in the same order of magnitude. This observed difference may be due to the internal environment inside the Petri dish, hence the internal O2 concentration, humidity, and temperature during bacterial growth were investigated. This work demonstrates, for the first time, a full successful workflow of bacterial growth using a sustainable bioplastic, providing a pathway to reducing the environmental impacts of SUPs in life science laboratories.

Biogenic Synthesis, Optimization, and characterization of zinc oxide nanoparticles using Rumex abyssinicus Jacq root extract for antioxidant and antibacterial activities

Nanoparticles may be synthesized through chemical, physical, and biological strategies, but the former strategies contain critical troubles, including environmental toxicity and cost-effectiveness. This work addresses adopting a green synthesis method for ZnO NPs using Rumex abyssinicus Jacq root extract for antibacterial and antioxidant programs. A UV–vis spectrophotometer optimized various factors, including temperature, pH, time, zinc acetate dihydrate attention, and the volume ratio of zinc acetate dihydrate to plant root extract. The biosynthesized ZnO NPs had been examined using exclusive characterization instrunments. ZnO NPs and Rumex abyssinicus Jacq root extract confirmed enormous inhibitory effects on pathogenic bacterial lines, inclusive of the gram-negative bacterial strains Escherichia coli and Staphylococcus typhi and the gram-positive bacterial pressure Staphylococcus aureus. ZnO NPs and Rumex abyssinicus Jacq root extract exhibited the best antioxidant sports. consequently, this has a look at confirmed that Rumex abyssinicus Jacq root extract is an effective decreasing agent for the synthesis of ZnO NPs, which exhibit antibacterial and antioxidant activities.

Novel Co(II), Cu(II) and Zn(II) complexes derived from thiazole containing Schiff base ligands: Green synthesis, antimicrobial and anti-cancer studies

Six novel metal complexes of Co(II), Cu(II), and Zn(II) were synthesized using a microwave-assisted method. These complexes were derived from Schiff base ligands prepared through the condensation of 4-(p-fluorophenyl)-5-methyl-2-aminothiazole with 3-methoxysalicyldehyde (L1) and 2-hydroxynaphthaldehyde (L2). Characterization techniques, including UV–vis, IR, NMR, and HR-MS confirm the tridentate nature of Co(II), Zn(II), and bidentate nature of Cu(II) complexes. Elemental and thermogravimetric analysis showed 1:2 (M: L) stoichiometry in metal complexes. Meanwhile, magnetic susceptibility and powder X-ray diffraction express the geometry and crystal systems of complexes. The antimicrobial analysis of the synthesized compounds indicates Cu(II) complexes have greater potency against gram-positive bacterial and fungal strains while Zn(II) complexes show a greater zone of inhibition against gram-negative bacterial strains. Moreover, MIC values of the most potent complexes [Cu(L2)2] and [Zn(L2)2] range from 190-375 µg/mL. Furthermore, ligands and their complexes have been tested for anticancer potential against MDA-MB 231 and A549 cell lines by MTT assay. [Zn(L1)2] and [Zn(L2)2] complexes were found to have potent activity with IC50 values of 16.7 µM, 24.1 µM, and 8.7 µM, 13.4 µM respectively on MDA-MB-231 and A549 cell lines compared to other complexes and parent ligands. Molecular docking study performed using the PyRx 0.8 (with RF-Score V2 scoring function) program against EGFR (PDB: 5XGM) showed strong binding interactions which supports the experimental results.

Green synthesis and antibacterial potency of Ag/CuO/ZnO nanoparticles derived from Psidium guajava L. extracts

Nanoparticles, characterized by their unique physicochemical properties, represent a significant frontier in interdisciplinary research, particularly within the realms of biomedicine and environmental science. This investigation delves into the eco-friendly synthesis of silver (Ag), copper oxide (CuO) and zinc oxide (ZnO) nanoparticles utilizing extracts derived from Psidium guajava L. The utilization of these botanical extracts presents a sustainable alternative to traditional nanoparticle fabrication methodologies, aligning with global sustainability imperatives and fostering environmentally conscious practices. The escalating global nanoparticle market, valued at over $30 billion in 2020 and projected to surpass $90 billion by 2027, underscores the economic significance and industrial relevance of nanoparticle research. This research trajectory fuels innovation across a spectrum of sectors, including healthcare, cosmetics and environmental remediation. The commercialization of nanoparticle-based products not only drives substantial revenue streams but also catalyzes advancements in research, development and manufacturing endeavors. Drawing upon aqueous extracts sourced from P. guajava., leaves and fruits, this study capitalizes on their inherent phytochemical composition to serve as stabilizing, reducing and capping agents during nanoparticle synthesis. Employing state-of-the-art characterization techniques such as UV-Vis spectroscopy, FTIR spectroscopy, FE-SEM and EDS facilitates a comprehensive analysis of the synthesized nanoparticles' physicochemical attributes. Assessment of the nanoparticles' antibacterial efficacy against gram-positive (Bacillus subtilis, Staphylococcus aureus) and gram-negative (Escherichia coli, Proteus vulgaris) bacterial strains reveals compelling results. Minimum inhibitory concentrations (MIC) elucidate notable efficacy, notably against P. vulgaris (3.75 mg/mL), S. aureus (7.5 mg/mL) and B. subtilis (10 mg/mL and 12.5 mg/mL), indicative of their potential biomedical applications in combating microbial infections.

Antibacterial and Cell-Viability of Hydroxyapatite Derived from Waste Marine Shell for Biomedical Applications

The present study discusses on the functional groups, structural characterization and thermal behaviour of Crassostrea angulata shell used for the synthesis of a biocompatible hydroxyapatite material. The hydroxyapatite was synthesized from C. angulata shell through precipitation method and characterized using XRD, FTIR, FE-SEM, EDX mapping, HR-TEM and SAED pattern. The formation of hydroxyapatite was confirmed from the high intense X-ray diffraction lines and by the presence of chemical groups such as PO43–, OH– and CO32–. The structural changes during the formation of hydroxyapatite from the thermal decomposition of C. angulata shell were studied through XRD and TG-DTA. The morphology study by FE-SEM indicates that the synthesized hydroxyapatite materials were in the form of clusters of rod-like particles. The SAED patterns and XRD spectral lines confirmed the crystalline nature of the synthesized hydroxyapatite. The antibacterial activity and cell viability assay of prepared hydroxyapatite were studied to assess its suitability in various biomedical applications. The antibacterial activity of hydroxyapatite was assessed against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus saprophyticus) bacterial strains. The cytocompatibility of hydroxyapatite was assessed through an MTT assay using osteoblast cells (MG-63 cell). Thus, the prepared hydroxyapatite shows good antibacterial action and cell viability nature and it can be applied in various biomedical applications.

Uropathogenic Bacterial Detection and Surveillance of Antimicrobial Resistance Pattern in Urine Specimens Referred to Al anbar Province

For clinicians treating patients, antimicrobial resistance is becoming a significant concern. This brief study was therefore conducted to find out how common it is for bacterial isolates that are resistant to multiple drugs (MDR), XDR, and PDR, as well as extensively drug-resistant (XDR), in Anbar hospital. The microbiology department cultivated the clinical samples and identified the bacterial strains. The detection of MDR, XDR, and PDR microorganisms was accomplished by analyzing the antibiotic susceptibility profile of various bacterial isolates. 257 children and adult patients from both sexes were included in this study. The total number of urine samples that gave positive bacterial culture results were 114 (44.4%) and the number of samples that gave negative results was 143(55.6%) . The antibiotic susceptibility profile of 114 bacterial strains was studied. 90(78.9) of gram-negative bacteria strains were MDR, (8.9%) (72.2%) XDR, and (18.9%) PDR was isolated. 24 (21.1%) Gram positive bacterial egative bacteria strains were MDR, (33.3%) (54.2%) XDR, and (12.5%) PDR was isolated. To effectively combat the threat of antibiotic resistance, all clinical microbiology laboratories need to closely monitor MDR, XDR, and PDR.

Antimicrobial and Enzymatic Activities of Mangrove-associated Actinomycetes

This study delves into the enzymatic and antimicrobial capabilities of actinomycetes isolated from the Setiu Wetland mangrove in Terengganu, Malaysia. A total of eighteen actinomycete bacteria were isolated and characterized from the site. These isolates underwent antimicrobial assessments targeting a representative range of Gram-positive bacteria, Gram-negative bacteria and a fungus were employed for the testing. The results of the antimicrobial evaluations demonstrated pronounced effectiveness of the majority of isolated actinomycetes against Gram-negative bacterial strains. Intriguingly, a notable observation was the inhibition against Streptococcus uberis on nutrient agar by 27.7% of the isolates. In conjunction with the antimicrobial investigations, an array of enzymatic assays encompassing amylase, protease, lipase, phosphate solubilization, urease, and cellulase were executed. The outcomes revealed that a substantial portion of the examined actinomycetes exhibited positive reactions in at least half of the conducted assays, with amylase and protease production being particularly prominent, were observed from 94% of the isolates. These findings, drawn from the amassed dataset, underscore the remarkable diversity of antimicrobial and enzymatic activities within the actinomycetes thriving in the mangrove environment. This diversity exemplifies the adaptability of these mangrove-associated actinomycetes, underscoring their capacity to generate a versatile spectrum of secondary metabolites and biochemical responses as a strategy for survival within this unique ecosystem.

Formulation and Evaluation of Antibacterial and Anti-Inflammatory Emulgel Containing Eugenia caryophyllus Buds Extract

ABSTRACT: Background: Eugenia caryophyllus is a valuable aromatic spice used in household cooking. Traditional healers frequently employ the plant, which is said to have therapeutic qualities, in herbal concoctions to treat a variety of illnesses and conditions. Objective: Eugenia caryophyllus clove buds have antibacterial, analgesic, and anti-inflammatory properties. The formulation of clove emulgel and its assessment using a variety of evaluation criteria were the main objectives of the current study. Clove emulgel was evaluated for its anti-inflammatory and anti-microbial properties. Materials and Procedures: We extracted and assessed the oils from Eugenia caryophyllus buds for phytochemical testing using solvents such as methanol, ethanol, petroleum ether, and N-hexane. We prepare emulgel and test it for spreadability, pH, and other organoleptic characteristics. We used egg albumin denaturation as a protein to measure the in vitro anti-inflammatory efficacy. We tested the antibacterial susceptibility using the agar-well diffusion method. Results: Alkaloids, saponins, tannins, steroids, carbohydrates, and glycosides were the phytochemical components found in clove bud extract. Physical factors such as color, consistency, and state—such as semi-solid, smooth, and brownish-gummy—are included in this category of evaluation parameters. The emulgel's pH was 5.35, its spreadability ranged from 1.6 to 2.5 cm, and no phase separation was noticed while the emulgel was stored. An in vitro anti-inflammatory test (spectroscopy method) and an antimicrobial test (zone of inhibition) were used to evaluate the anti-inflammatory activity of emulgel. Comparing clove oil emulgel to a typical medication, these evaluations found that it demonstrates strong anti-inflammatory and antibacterial resistance. Conclusion: In conclusion, Clove Buds Emulgel has demonstrated antibacterial activity against both gram-positive and gram-negative bacterial strains. Emulgel demonstrated the inhibitory response percentage in relation to the standard. This validates the roles that E. caryophyllus has been shown to play in protecting human health. This innovative emulgel mixture was applied to arthritis to lessen microbial infection and joint discomfort. In addition, more preclinical and clinical trials will be needed for this research in order to successfully commercialize the emulgel formulation for the treatment of inflammation and antimicrobial activity.

Flavobacterium nakdongensis sp. nov., Isolated from Fresh Water during the Cyanobacterial Bloom Period.

A novel Gram-negative bacterial strain, 20NA77.7T , was isolated from fresh water of the Nakdong River. Strain 20NA77.7T shared the highest similarity with Flavobacterium indicum GPTSA100-9T (97.91%) and Flavobacterium urocaniciphilum DSM 27078T (96.24%) in the 16S rRNA gene sequence. The digital DNA-DNA hybridization and average nucleotide identity values for strain 20NA77.7T with Flavobacterium species were below 20.8% and 77.33%, respectively. The major fatty acids of strain 20NA77.7T were identified as iso-C15:0, iso-C16:0, iso-C15:1 G, anteiso-C15:0, iso-C15:0 3OH, and isoC16:0 3OH. Strain 20NA77.7T contained phosphatidylethanolamine, one unidentified aminolipid, and three unidentified lipids as polar lipids and menaquinone-6 as menaquinone. The polyphasic evidence supports the classification of strain 20NA77.7T as a novel species belonging to the genus Flavobacterium, for which the name Flavobacterium nakdongensis is proposed. The type strain is 20NA77.7T (= KCTC 102000T = LMG 33137T ).

Understanding of the effect of concentration of green polysaccharide-based TiO2 for photoelectrochemical, photocatalytic, and antibacterial properties

Composites formed by TiO2/babassu mesocarp were synthesized by the sol-gel method with a percentage variation of 3 % and 5 % (w/v) called 3BBT and 5BBT, respectively. The materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV–Vis Diffuse Reflectance Spectroscopy, and surface area was calculated by the Brunauer–Emmett–Teller method (BET). Electrochemical studies were carried out, and photocurrent data was obtained as a function of the variation in gallic acid concentration and applied potential. The photocatalytic efficiency of the material was investigated by the degradation of the Methylene Blue (MB) dye under light. The antimicrobial activity of the materials was tested on Gram-positive and Gram-negative strains. XRD showed that the composites obtained are in the anatase crystallographic phase, and the increase in the percentage of babassu mesocarp influenced the reduction of peak intensity and crystallite size. The microscopy showed a more porous aspect of the 3BBT material and a denser aspect of the 5BBT material. It was confirmed by textural characterizations, which showed reduced pore volume and specific surface area of 5BBT compared to 3BBT. Increasing the percentage of polysaccharides caused a reduction in the band gap energy of TiO2 (Eg = 2.90 eV and Eg = 2.47 eV for 3BBT and 5BBT, respectively). The electrochemical study showed that the composites could detect gallic acid, providing increased sensitivity according to the increased applied photocurrent. They also showed good precision for the photoelectrochemical measurements, as verified in the repeatability test (2.66 % and 3.68 % RPD for 3BBT and 5BBT, respectively). The 3BBT showed greater photocatalytic capacity, discoloring 63.4 % of the MB dye in 120 min under light and electrons are the main species involved in photocatalytic activity demonstrated by 3BBT. Antibacterial tests indicated that the 5BBT material exhibits a greater capacity to inhibit E. coli and S. aureus bacteria.

Ultrasonic-aided preparation of poly(vanillin-co-thiophene)/green Fe₃O₄ nanocomposites via solution mixing for methyl orange adsorption and antibacterial applications

This work describes the preparation of novel nanocomposite materials comprising a newly synthesized semiconducting copolymer, poly(vanillin-co-thiophene) (PVTH), blended with different weight proportions (3 %, 6 %, and 9 % by weight) of greenly synthesized magnetite nanoparticles (GFe3O4 MNPs) via solution mixing, assisted by ultrasonic irradiation. PVTH copolymer was synthesized through the polycondensation of vanillin, a bioderived aldehyde, and thiophene, catalyzed by sulfuric acid. GFe3O4 MNPs were prepared via the coprecipitation method with mint extract as an environmentally friendly stabilizer. The physicochemical properties of the prepared samples were investigated by 1H NMR, 13C NMR, FTIR, XRD, UV–vis, TGA, FE-SEM/Eds, AFM, VSM, tauc plot method and the four-points probe measurement. The samples were evaluated for two applications: methyl orange (MO) adsorption from aqueous solutions and antibacterial activities against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus) bacterial strains. The results showed that ultrasound irradiation facilitated the easy preparation of well-dispersed and homogeneous nanocomposites with combined semiconducting and magnetic properties and improved thermal stability compared to the parent PVTH. The most effective nanocomposite for MO removal was the sample containing 9 % GFe3O4 MNPs, whose adsorption behavior followed pseudo-second-order kinetics and Freundlich isotherm. Its maximum adsorption capacity was 103.79 mg g−1. In addition, all samples showed antibacterial action against the tested bacterial strains, with PVTH showing the highest efficacy, followed by PVTH/GFe3O4 nanocomposites.

Adsorptive potential of dispersible chitosan-coated biogenic iron oxide nanocomposite for enhanced anti-bacterial activity against gram-positive and gram-negative bacterial pathogens

The use of various biomaterials, such as plants or microbes, to create nanoparticles (NPs), is seen as a viable strategy in green nanotechnology. The synthesis of low-cost, energy-efficient, nontoxic, ecologically acceptable metallic nanoparticles has recently become a critical topic. The biosynthesis of iron oxide NPs using pomegranate peel extract has been investigated. Biogenic iron oxide NPs were coated with highly porous chitosan as a supporting material to enhance applicability of NPs for wastewater remediation. Biogenic magnetic NPs and its composite were characterized by scanning electron microscope, X-ray diffraction, and Fourier Transformer Infrared spectroscopy (FTIR). Our study focused on the ability of biogenic magnetite Fe3O4 NPs and its bio-composite for removal of As+5 ions from wastewater. Adsorption isotherms were obtained using metal ion concentrations ranging from 5 to 25 mg/L. The Langmuir adsorption model was validated by our data. The reaction kinetics of the adsorption process were pseudo-second order. Interestingly, the bio-composite achieved 90% As+5 removal at pH4. In addition, the prepared nanocomposite was characterized using various analytical techniques to confirm its physicochemical properties. The adsorptive capacity of the nanocomposite was evaluated by studying the removal of pollutants and contaminants from aqueous solutions. Additionally, the antibacterial activity of the nanocomposite was assessed against a panel of clinically relevant Gram-positive and Gram-negative bacterial strains, including Staphylococcus epidermidis (RCMB 9241, ATCC 12228), Staphylococcus saprophyticus (RCMB 010028, ATCC 15305), Enterococcus faecalis (RCMB 010052), Streptococcus salivarius (ATCC 13415), Escherichia coli (RCMB 010052, ATCC 25922), Salmonella enterica serovar Typhimurium (RCMB 006(1), ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853). Our findings have important implications in the field of low-cost, easy, and environmentally friendly water bioremediation.

Assessment of Bryophyllum pinnatum mediated Ag and ZnO nanoparticles as efficient antimicrobial and cytotoxic agent.

Bryophyllum pinnatum is used to cure infections worldwide. Although the flavonoids of this plant are well known, it is still unknown how much of the plant's Ag and ZnO nanoparticles are beneficial. In the current research work, silver and zinc oxide nanoparticles were prepared using Bryophyllum pinnatum extract. The synthesized particles were characterized by UV-visible spectroscopy, SEM, EDS, XRD and FTIR. Synthesized particles were subjected to evaluation of their bactericidal and antifungal activity at various doses. Uv vis spectra at 400nm corresponding to AgNPs confirmed their synthesis. Strong peaks in the EDS spectra of Ag and ZnO indicate the purity of the sample. The scanning electron microscopic images of ZnONPs showed a size of about 60nm ± 3nm, which demonstrated the presence of triangular-shaped ZnO nanoparticles. Green synthesized nanoparticles showed bactericidal activity against both Gram-positive (Micrococcus luteus, Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Agrobacterium tumifaciens, Salmonella setubal, Enterobacter aerogenes) strains. AgNPs proved to be more effective against Gram-negative bacterial strains compared to Gram-positive owing to MIC values (10 ppm and 20 ppm respectively). Whereas, ZnONPs were found more effective against Gram-positive bacteria with lower MIC values (10 ppm) as compared to Gram-negative ones (20 ppm). Also, the synthesized nanoparticles exhibited moderate dose-dependent antifungal activity against tested fungal strains ranging from 10 to 70%. Cytotoxicity of nanoparticles was found significant using Brine shrimp's lethality assay with IC50 values of 4.09 ppm for AgNPs, 13.72 ppm for ZnONPs, and 24.83 ppm for plant extract. Conclusively, Ag and ZnO nanoparticles were more effective than plant extract and AgNPs had higher activities than those of ZnONPs. Further research is warranted to explore the precise mechanism of action and the potential applications of these nanoparticles in the medical field.

Unprecedented one-pot synthesis of 3,4-dihydropyrimidine-2-(1h)-ones catalyzed by hydrazine sulfate through Biginelli reaction, ADMET property, molecular docking studies and their antibacterial activity on Bacillus brevis and E. coli

The syntheses of 3,4-dihydropyrimidin-2(1H)-ones by one-pot, three-component condensation of aldehydes, β-ketoesters and urea or thiourea have been made more simple and efficient by using 20 mol% hydrazine sulfate as catalyst. Aldehydes, β-ketoesters and urea are cyclocondensed in the presence of hydrazine sulfate to produce dihydropyrimidines in ethanol under reflux conditions. The advantages of using hydrazine sulfate as a catalyst over the traditional Biginelli reaction conditions include outstanding yields (80–91%) and a shorter (10–15 hours) reaction time. In order to evaluate the antibacterial efficiencies of the synthesized compounds, we have studied the inhibitions of microbial proliferation of both Gram-positive (Bacillus brevis) and Gram-negative (E. coli) bacterial strains in comparison to a control group. The microbial inhibitions occur in the range of 40–98% by different derivatives of dihydropyrimidinones. Molecular docking studies of the synthesized compounds have also been done using software tools such as SwissADME.

Suspension-Sprayed Calcium Phosphate Coatings with Antibacterial Properties.

Prosthesis loosening due to lack of osteointegration between an implant and surrounding bone tissue is one of the most common causes of implant failure. Further, bacterial contamination and biofilm formation onto implants represent a serious complication after surgery. The enhancement of osteointegration can be achieved by using bioconductive materials that promote biological responses in the body, stimulating bone growth and thus bonding to tissue. Through the incorporation of antibacterial substances in bioconductive, biodegradable calcium phosphate (CaP) coatings, faster osteointegration and bactericidal properties can be achieved. In this study, Cu-doped CaP supraparticles are spray-dried and suspension-sprayed CaP ceramic coatings with antibacterial properties are prepared using high-velocity suspension flame spraying (HVSFS). The objective was to increase the coatings' porosity and investigate which Cu-doped supraparticles have the strongest antibacterial properties when introduced into the coating layers. Biocompatibility was tested on human Osteosarcoma cells MG63. A porosity of at least 13% was achieved and the supraparticles could be implemented, enhancing it up to 16%. The results showed that the addition of Cu-doped supraparticles did not significantly reduce the number of viable cells compared to the Cu-free sample, demonstrating good biocompatibility. The antimicrobial activity was assessed against the bacterial strains Escherichia coli and Staphylococcus aureus, with Safe Airborne Antibacterial testing showing a significant reduction in both Gram-positive and Gram-negative strains on the Cu-doped coatings.

Thymus algeriensis essential oil: Phytochemical investigation, bactericidal activity, synergistic effect with colistin, molecular docking, and dynamics analysis against Gram-negative bacteria resistant to colistin

Due to the increasing resistance prevalence to the last line of antibiotics, such as colistin, and the rising threat of multi-drug resistant bacteria, it is crucial to find alternative therapeutic options. The current study focuses on evaluating antibacterial activities alone and in combination with colistin of Thymus algeriensis essential oil (TA-EO) against colistin-resistant Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli co-harboring mcr-1 gene. GC/MS was used to determine the chemical composition of TA-EO. Disc diffusion and microdilution techniques were used to evaluate the antimicrobial activities of TA-EO. Synergism between colistin and TA-EO was evaluated by checkerboard assay. The major compounds of TA-EO were docked with known enzymes involved in resistance to colistin, as well as the biosynthesis of peptidoglycan and amino acids. GC/MS revealed that TA-EO was of carvacrol chemotype (67.94 %). The TA-EO showed remarkable antibacterial activities against all Gram-negative bacterial strains, with the diameter of inhibition zones varied between 30 and 50 mm and a ratio MBC/MIC equal to 1 for the vast majority of bacterial isolates. Interestingly, the checkerboard showed synergism between TA-EO and colistin against colistin-resistant Escherichia coli co-harboring mcr-1 gene (FICI˂1) and reduced the MIC of colistin by 16- to 512-fold and those of TA-EO by 4- to 16-fold. The docking study demonstrated that carvacrol had high binding free energies against MCR-1, a phosphoethanolamine transferase extracellular domain, and its catalytic domain implicated in resistance to colistin, and undecaprenyl pyrophosphate synthase in complex with magnesium which is involved in bacterial peptidoglycan biosynthesis. The molecular dynamics study for 100-ns also revealed the stability of the MCR-1/carvacrol complex with a constant surface area over the simulation. These results support using carvacrol or TA-EO as a bactericidal agent, either alone or in combination with colistin, to treat infections caused by colistin-resistant Gram-negative bacteria.

Investigating the Efficacy of Various Natural Products in Raw Form against Multidrug-Resistant Bacteria.

The alarming increase in antibiotic resistance urges alternative and efficacious antimicrobial solutions. Historically, medicinal plants have been used for therapeutic purposes, such as relieving pain and healing wounds. However, the evaluation of the natural therapeutic effects of medicinal plants in a manner that resembles how humans typically consume them is lacking. Therefore, in this study, many medicinal plants known to have some antimicrobial effects, including Frankincense, Garlic, Myrrh, and Ginger, were evaluated for their direct antibacterial activity in raw form. The direct antimicrobial activity of medicinal plants was evaluated against a variety of Gram-positive and Gram-negative bacterial strains, such as Staphylococcus aureus (S. Aureus), Acinetobacter baumannii and Klebsiella pneumoniae using agar well diffusion method and turbidity measurements in suspension culture. Out of all the tested medicinal plants, only raw garlic (Allium sativum) powder, when dissolved in water or vinegar, offered a straightforward antibacterial activity. A combination of garlic extract and vinegar increased antibacterial activity. Aqueous garlic extracts displayed robust antimicrobial activity against many resistant bacteria. Other medicinal plants used in this study had absent or minimal antibacterial effects. Only garlic in its raw form was effective against antibiotic-resistant bacteria. The increase in the antibacterial activity of garlic when combined with vinegar suggests the synergistic activity of garlic. The straightforward antibacterial action of raw garlic may be strategically harnessed to combat the continuous challenge of increasing antibiotic resistance. This work promotes additional testing of more natural products (in raw form) and assesses their therapeutic effects clinically.

Antibacterial and cytocompatible silver coating for titanium Boston Keratoprosthesis.

The Boston Keratoprosthesis (BKPro) serves as a medical solution for restoring vision in complex cases of corneal blindness. Comprising a front plate made of polymethylmethacrylate (PMMA) and a back plate of titanium (Ti), this device utilizes the beneficial biomaterial properties of Ti. While BKPro demonstrates promising retention rates, infection emerges as a significant concern that impacts its long-term efficacy. However, limited research exists on enhancement of BKPros through intrinsic infection-preventing mechanisms. In this regard, metal ions, especially the well-known Ag+ ions, are a promising alternative to obtain implants with innate antibacterial properties. However, little information is available about the effects of Ag in corneal tissue, especially within human corneal keratocytes (HCKs). In this work, an electrodeposition treatment using a constant pulse is proposed to attach Ag complexes onto rough Ti surfaces, thus providing antibacterial properties without inducing cytotoxicity. Complete physicochemical characterization and ion release studies were carried out with both control and Ag-treated samples. The possible cytotoxic effects in the short and long term were evaluated in vitro with HCKs. Moreover, the antibacterial properties of the silver-treated surfaces were tested against the gram-negative bacterial strain Pseudomonas aeruginosa and the gram-positive strain Staphylococcus epidermidis, that are common contributors to infections in BKPros. Physicochemical characterization confirmed the presence of silver, predominantly in oxide form, with low release of Ag+ ions. Ag-treated surfaces demonstrated no cytotoxicity and promoted long-term proliferation of HCKs. Furthermore, the silver-treated surfaces exhibited a potent antibacterial effect, causing a reduction in bacterial adhesion and evident damage to the bacterial cell walls of P. aeruginosa and S. epidermidis. The low release of Ag+ ions suggested reactive oxygen species (ROS)-mediated oxidative stress imbalance as the bactericidal mechanism of the silver deposits. In conclusion, the proposed electrodeposition technique confers antibacterial protection to the Ti backplate of BKPro, mitigating implant-threatening infections while ensuring non-cytotoxicity within the corneal tissue.

In-vitro activities of essential antimicrobial agents including aztreonam/avibactam, eravacycline, colistin and other comparators against carbapenem-resistant bacteria with different carbapenemase genes: A multi-centre study in China, 2021

Carbapenem-resistant bacteria (CRB), including carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Enterobacterales (CRE), pose a considerable threat to public health in China. Eravacycline, aztreonam/avibactam and colistin are important antimicrobial agents for the treatment of serious infections caused by CRB. This study aimed to evaluate the prevalence of CRB strains, and the susceptibility of commonly used clinical antimicrobial agents against strains with different carbapenemase genes. In total, 7194 gram-negative bacteria strains were collected from different regions of China, and 924 carbapenem-resistant strains were identified. All strains were from confirmed infections. Antimicrobial susceptibility testing, covering 21 antimicrobial agents including aztreonam/avibactam, eravacycline, colistin and other comparators, was performed using the broth microdilution method. Carbapenemase genes (blaKPC, blaNDM, blaOXA, blaIMP and blaVIM) were screened using polymerase chain reaction amplification and sequence analysis. All statistical analyses were performed using Statistical Package for the Social Sciences Version 23.0. The isolation rates of CRE, CRAB and CRPA were 6.31% (332/5265), 62.95% (440/699) and 15.20% (152/1000), respectively. The predominant carbapenemase in carbapenem-resistant Escherichia coli (CRECO) was NDM, while in carbapenem-resistant Klebsiella pneumoniae (CRKP), it was KPC. All CRAB produced OXA-23, and 85.52% of CRPA did not produce any of the following carbapenemases: NDM, KPC, VIM, IMP and OXA. Aztreonam/avibactam, colistin and eravacycline exhibited high antimicrobial activity against different species producing various carbapenemases. Compared with ceftazidime/avibactam, aztreonam/avibactam demonstrated superior antimicrobial activity, particularly pronounced in CRECO and strains producing metallo-beta-lactamases. In comparisons between tigecycline and eravacycline, the latter maintained higher antimicrobial activity across different species. Antimicrobial agents exhibited varying levels of activity against strains with different resistance mechanisms. Using aztreonam/avibactam, eravacycline and colistin to treat infections caused by CRB offers significant advantages. These findings will guide clinical practice and optimize antimicrobial administration.

Antimicrobial effect of lactoferrin and glycerol monolaurate on selected bacteria associated with newborn infections

Human breast milk contains a rich array of bioactive substances, such as immunoglobulins, lactoferrin antimicrobial peptides, and glycerol monolaurate, which play a crucial role in providing immune protection to infants. Infant formula manufacturers strive to match mother's milk's nutritional makeup, including immune-boosting ingredients. Lactoferrin and glycerol monolaurate (GML) are important antibacterial compounds in human milk. The study aimed to investigate the effect of bovine lactoferrin (bLf) and GML in preventing the growth of inoculated bacteria into infant formula. The study examined both individual and combined use of these components. The bacteria that were tested included: 1) Gram-negative bacteria: Cronobacter sakazakii strains 12868 and 29004, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, and 2) Gram-positive bacteria: Methicillin-resistant Staphylococcus aureus (MRSA), and Listeria monocytogenes. The result of the agar diffusion assays showed that bLf, at a concentration of 16 mg/disc, exhibited strong inhibition (≥20 mm) of all the selected bacterial strains. On the other hand, GML at a concentration of 8 mg/disc showed strong inhibition of all strains; however, Gram-positive bacteria were more susceptible, so a concentration of 5 mg/disc was enough to achieve strong inhibition of these strains. The minimal bactericidal concentrations (MBC) analysis aimed to achieve a >3-log reduction in the growth of various bacterial strains. The results showed that S. enterica Typhimurium and L. monocytogenes were more susceptible to bLf than the other strains (MBC: 7 and 4.8 mg/ml, respectively, vs. 14.9–18.4 mg/ml for the other strains). In contrast, MRSA and L. monocytogenes were more susceptible to GML (MBC: 6 and 10 mg/ml, respectively, vs. 16–18 mg/ml for Gram-negative strains). The results of reconstituted powdered infant formulas (RPIF), with the addition of bLf, GML, or both at pathogen-specific MBC, showed significant log reductions in the growth of experimentally inoculated bacteria compared to the control at different time intervals. All bacterial strains exposed to bLf and GML exhibited >3-log reduction within 72 h, with Gram-positive strains showing >7-log reduction. GML and bLf combined had a stronger anti-bacterial activity than individual components, indicating the potential of combining GML and bLf as natural agents against specific pathogenic bacteria. Future studies are needed to understand the potential use of these compounds in different food matrices and clinical settings.