Antibacterial Effect Research Articles

Studying the Effect of Magnetron Copper Deposition on the Surface Topography of Biodegradable Antibacterial Coating

Background: The surface properties of the materials used significantly influence the success and longevity of medical implants. Increasing surface roughness promotes osteoblast activity and osseointegration, while biodegradable materials such as copper have shown potential for antimicrobial applications. However, the effect of coating parameters on surface topography is not well investigated. Methods: Sputtering of copper was performed using EPOS-PVD-440 system (Zelenograd, Russia). The samples were examined by Scanning Electron Microscopy (SEM) with subsequent image processing in Mountains software (Digital Surf). Antibacterial efficacy was evaluated against Staphylococcus aureus by measuring the zone of inhibition. Additionally, copper ion release was monitored over time to assess its correlation with changes in surface topography. Results: Higher sputtering currents increased surface roughness and particle size, with a significant release of copper ions within the first 24 hr of immersion. Samples sputtered at higher currents exhibited coarser grain structures. The release of copper ions in the simulated biological environment led to further changes in surface topography, highlighting the critical influence of sputtering parameters on coating properties. Conclusion: Optimizing magnetron copper deposition parameters enhances the surface topography and antibacterial effectiveness of biodegradable coatings on implants.

In vitro antimicrobial activity of silver nanoparticles against selected Gram-negative and Gram-positive pathogens

Background and aim. Infections caused by pathogenic bacteria increase patient morbidity and mortality and significantly raise treatment costs. The use of silver nanoparticles as an alternative treatment for S aureus, E coli, MRSA, E faecalis, K pneumoniae and P aeruginosa indicates their antibacterial effect and prompts medical research to consider the next generation of antibacterial drugs that could change antibiotic therapy. By combining silver nanoparticles with different classes of antibiotics, the antibacterial effect is evidenced by increased values of the inhibition zone compared to the values obtained for some antibiotics commonly used in the treatment of bacterial infections. This study focuses on comparing the antibacterial activity of antibiotics versus antibiotics combined with silver nanoparticles against various bacteria, by comparing inhibition zones obtained for both. We aim to prove that the size of the inhibition zone for antibiotics combined with silver nanoparticles is greater, thus confirming the improved antibacterial effect. Metods. In this study we tested the antibacterial activity of solutions of silver nanoparticles alone or in combination with different antibiotics. We used standard bacterial strains, ATCC, both Gram positive bacteria Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, as well as Gram negative bacteria Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, but also on clinical isolates: a strain MRSA (Methicillin Resistant Staphylococcus aureus) and a PDR strain (pan drug resistant) of Klebsiella pneumoniae. Bacterial identification was performed using Vitek MS analyzer (bioMerieux). Antibiotic susceptibility determination was performed with VITEK2 COMPACT SYSTEM (bio Merieux, Inc Durham NC) with ready to use VITEK AST cards. The interpretation of the results was done in compliance with EUCAST 2023-2024 standards. Testing was performed for several classes of antibiotics, silver nanoparticle solutions in 2 concentrations (10 μg/mL and 100 μg/mL) and for combinations of antibiotics with silver nanoparticle solutions. The diameter of the inhibition zone (ZOI) for silver nanoparticles, antibiotics and silver nanoparticles combined with antibiotic against each bacterium was expressed in millimeters. The Kirby-Bauer disk-diffusion method, in accordance with current EUCAST standards, was used to analyze the antibacterial effect of antibiotics, silver nanoparticles, and antibiotics combined with silver nanoparticles at biocompatible doses of 10 and 100 μg/mL. The experiments were conducted in triplicate, and the results were almost identical. Results. The results of this study show that the silver nanoparticles displayed antibacterial activity, proven by the appearance of the inhibition zone, in various sizes, for all bacteria studied. The antibiotic classes tested were beta-lactamins, first, second, third and fourth generation cephalosporins, macrolides, fluoroquinolones, lincosamides, aminoglycosides, glycopeptides, tetracyclines, oxazolidinones, sulfonamides, rifamycins, amphenicols. Testing S aureus ATCC 29213, the highest zone of inhibition was demonstrated for cephalosporins (32.6667 ± 0.701 mm), macrolides (31.6667 ± 0.701 mm, and lincosamides (29.6667 ± 0.701 mm). Testing MRSA (internal code GR0333), the highest zone of inhibition for combination of silver nanoparticles and antibiotics was demonstrated for fluoroquinolones (36.3333 ± 0.701 mm), lincosamides (32.3333 ± 0.701 mm), Fusid acid (32.3333 ± 0.701 mm) and aminoglicosides (31.3333 ± 0.701 mm). Testing E coli ATCC 25922 the highest zone of inhibition was for Fosfomycine, 39 mm and for E faecalis ATCC 29212 for aminoglicosides was 19 mm. For K pneumoniae (internal code GQ8575) the inhibition zone for silver nanoparticles 100 μg/mL was 12.3333 ± 0.701 mm and for P aeruginosa ATCC 27253 was 16 ± 1.214 mm. Conclusions. The use of metallic nanoparticles, especially silver ones, as antimicrobial agents with definite bactericidal activity has led medical specialists to consider this new treatment which may change antibacterial therapy. Studies of in vitro combinations between silver nanoparticles and different classes of antibiotics represent a highly efficient and effective new antibacterial treatment against multidrug-resistant bacteria. To avoid the problem of antimicrobial resistance associated with conventional antibiotics, it is necessary to understand the adaptive mechanisms of bacteria under the action of metal nanoparticles, which could be exploited in future studies. Further in vitro and in vivo studies that would assess specify the biocompatibility and toxicity of silver nanoparticles will make these super nanomaterials the medicines of the future.

Synergistic Bactericidal Effects of Quaternary Ammonium Compounds with Essential Oil Constituents.

Antimicrobial tolerance is a significant concern in the food industry, as it poses risks to food safety and public health. To overcome this challenge, synergistic combinations of antimicrobials have emerged as a potential solution. In this study, the combinations of two essential oil constituents (EOCs), namely carvacrol (CAR) and eugenol (EUG), with the quaternary ammonium compounds (QACs) benzalkonium chloride (BAC) and didecyldimethylammonium chloride (DDAC) were evaluated for their antimicrobial effects against Escherichia coli and Bacillus cereus, two common foodborne bacteria. The checkerboard assay was employed to determine the fractional inhibitory concentration index (FICI) and the fractional bactericidal concentration index (FBCI), indicating the presence of bactericidal, but not bacteriostatic, synergy in all QAC-EOC combinations. Bactericidal synergism was clearly supported by Bliss independence analysis. The bactericidal activity of the promising synergistic combinations was further validated by time-kill curves, achieving a >4-log10 reduction of initial bacterial load, which is significant compared to typical industry standards. The combinations containing DDAC showed the highest efficiency, resulting in the eradication of bacterial population in less than 2-4 h. These findings emphasize the importance of considering both bacteriostatic and bactericidal effects when evaluating antimicrobial combinations and the potential of EOC-QAC combinations for sanitization and disinfection in the food industry.

Comparative evaluation of the remineralizing potential of Salvadora persica and probiotic yogurt on incipient enamel lesions: An ex-vivo study.

Salvadora persica (miswak) is known to exert antibacterial, antifungal, antioxidant, and anticariogenic effects by elevating the pH of plaque after the consumption of sucrose. The study aimed to compare the effectiveness of S. persica and probiotic yogurt in the remineralization of tooth enamel on artificially produced enamel lesions. A total of 40 intact human premolars were collected and each tooth was sectioned longitudinally into 2 identical halves in a buccolingual direction. The buccal halves were selected for inclusion in this study, and standardized windows (5 mm× 3 mm) were isolated on the buccal surface of the enamel. The samples were incubated in a demineralizing solution at 37°C for 96 h. Subsequently, they were randomly selected for treatment with one of the experimental remineralizing solutions (S. persica or probiotic yogurt). After treatment, the samples were examined using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and polarized light microscopy at baseline, after demineralization and after remineralization. The remineralizing effect of S. persica was found to be greater than that of probiotic yogurt. With regard to mineral content, S. persica exhibited the highest calcium and phosphorus levels among all groups. No significant differences were observed between the samples treated with S. persica and normal enamel. Salvadora persica extract has been demonstrated to effectively reduce the demineralization of enamel in experimental conditions. Furthermore, it has the potential to restore the mineral content to its original level.

Comparative Effect of Antioxidant and Antibacterial Potential of Zinc Oxide Nanoparticles from Aqueous Extract of Nepeta nepetella through Different Precursor Concentrations.

Antibiotic resistance is a global health crisis caused by the overuse and misuse of antibiotics. Accordingly, bacteria have developed mechanisms to resist antibiotics. This crisis endangers public health systems and medical procedures, underscoring the urgent need for novel antimicrobial agents. This study focuses on the green synthesis of ZnO nanoparticles (NPs) using aqueous extracts from Nepeta nepetella subps. amethystine leaves and stems, employing different zinc sulfate concentrations (0.5, 1, and 2 M). NP characterization included transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), along with Fourier transform infrared spectroscopy (FTIR) analysis. This study aimed to assess the efficacy of ZnO NPs, prepared at varying concentrations of zinc sulfate, for their capacity to inhibit both Gram-positive and Gram-negative bacteria, as well as their antioxidant potential using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. SEM and TEM results showed predominantly spherical NPs. The smallest size (18.5 ± 1.3 nm for leaves and 18.1 ± 1.3 nm for stems) occurred with the 0.5 M precursor concentration. These NPs also exhibited remarkable antibacterial activity against both Gram-positive and Gram-negative bacteria at 10 µg/mL, as well as the highest antioxidant activity, with an IC50 (the concentration of NPs that scavenge 50% of the initial DPPH radicals) of 62 ± 0.8 (µg/mL) for the leaves and 35 ± 0.6 (µg/mL) for the stems. NPs and precursor concentrations were modeled to assess their impact on bacteria using a 2D polynomial equation. Response surface plots identified optimal concentration conditions for antibacterial effectiveness against each species, promising in combating antibiotic resistance.

Experimental study of the antibacterial effect of anodic dissolution of a copper electrode used in endodontic treatment of teeth

BACKGROUND: One of the possible ways to improve the quality of dental treatment with obliterated root canals is the use of transcanal direct current exposure. AIM: The aim of the study was to investigate the comparative antibacterial activity of anodic dissolution of copper and silver-copper electrodes used in the endodontic treatment of teeth in the experiment. MATERIALS AND METHODS: An experimental study was performed by implementing a technique for the automatic cultivation of microorganisms in liquid culture media. We used for the study clinical isolates of individual strains of bacteria and yeasts, namely: S. constellatus, P. intermedia, C. albicans, as well as mixed cultures: 1) S. constellatus + F. nucleatum; 2) Streptococcus sanguis + Enterococcus faecium obtained from the root canals of the teeth during treatment of chronic pulpitis. RESULTS: The results of the study showed that anodic dissolution of both silver-copper and copper electrodes had a significant and, in general, unidirectional antibacterial effect. At the same time, it was found that, if for clinical isolate of P. intermedia the use of a silver-copper electrode was more effective, then for S. constellatus and C. Albicans strains, as well as for mixed cultures of pathogenic microorganisms S. constellatus + F. nucleatum and Streptococcus sanguis + Enterococcus faecium anodic dissolution of a copper electrode showed a more pronounced antibacterial effect. CONCLUSION: In endodontic treatment of teeth with partially obliterated root canals, along with anodic dissolution of silver-copper electrodes, it is possible to use anodic dissolution of copper electrodes as a means capable of having a pronounced antibacterial effect.

Strain-Programmed Adhesive Patch for Accelerated Photodynamic Wound Healing.

As an alternative to tissue adhesives, photochemical tissue bonding has been investigated for advanced wound healing. However, these techniques suffer from relatively slow wound healing with bleeding and bacterial infections. Here, we present the versatile attributes of afterglow luminescent particles (ALPs) embedded in dopamine-modified hyaluronate (HA-DOPA) patches for accelerated wound healing. ALPs enhance the viscoelastic properties of the patches, and the photoluminescence (PL) and afterglow luminescence (AL) of ALPs maximize singlet oxygen generation and collagen fibrillogenesis for effective healing in the infected wounds. The patches are optimized to achieve the strong and rapid adhesion in the wound sites. In addition, the swelling and shrinking properties of adhesive patches contribute to a non-linear behavior in the wound recovery, playing an important role as a strain-programmed patch. The protective patch prevents secondary infection and skin adhesion, and the patch seamlessly detaches during wound healing, enabling efficient residue clearance. In vitro, in vivo, and ex vivo model tests confirm the biocompatibility, antibacterial effect, hemostatic capability, and collagen restructuring for the accelerated wound healing. Taken together, this research collectively demonstrates the feasibility of HA-DOPA/ALP patches as a versatile and promoting solution for advanced accelerated wound healing, particularly in scenarios involving bleeding and bacterial infections. This article is protected by copyright. All rights reserved.

In silico and in vitro inhibition abilities of novel benzene sulfonamides on carbonic anhydrase and choline esterases

Compounds that possess a benzene sulfonamide structure are utilized in a wide range of fields. It is reported in the literature that many compounds belonging to this class of compounds exhibit various pharmacological properties such as antibacterial, antifungal, antiviral, anticancer, inflammatory, antiglaucoma, and anticholinergic effects. Carbonic anhydrase (CA) enzymes play a critical role in pH regulation, long-term synaptic turnover and are therefore thought to be associated with such diseases as mental retardation, Alzheimer’s disease (AD) and Down syndrome. Studies have reported that there is an increase in the levels of hCA-I and hCA-II isoenzymes in AD. AD is a complex, multifactorial disorder, so therapy should probably address not only the cholinergic system but also additional systems. Based on these features, a series of novel substituted benzene sulfonamides were synthesized from 1,2,3-trimethoxy-5-methylbenzene. Sulfonyl chloride 9 was synthesized from the reaction of 1,2,3-trimethoxy-5-methylbenzene and excess chlorosulfonic acid. The reaction of the obtained sulfonyl chloride with NH3 and N-alkyl amines, aniline, and phenethylamine gave substituted benzene sulfonamide derivatives 10–16. The synthesized compounds were evaluated for their carbonic anhydrase (hCA I-II), acetyl cholinesterase (AChE) and butyryl cholinesterase (BChE) inhibitory properties. Some of the substituted benzene sulfonamide derivatives 10–16 showed inhibitory effect on hCA isoenzymes. The Ki values determined for the hCA I enzyme are in the range of 102.01–147.19 µM. Benzene sulfonamide derivatives 10–16 showed an inhibitory effect on AChE and BChE. The Ki values determined for AChE and BChE enzymes are in the range of 28.76–308.08 µM and 42.80–445.60 µM, respectively. It was determined that sulfonamides 15–16 were selective inhibitors for the hCA I and 10 showed 11-fold more selectivity on AChE than BChE. In addition, the in-silico SAR and ADME properties of the synthesized compounds were also investigated.

Laser Therapy Versus Traditional Scaling and Root Planing: A Comparative Review.

Scaling and root planing (SRP) removes bacterial plaque, calculus, and associated microorganisms from the surface of the tooth and the surrounding soft tissue. While complete eradication of pathogenic microbes is impossible, gross removal can lower the microbial load, which in turn reduces inflammation and contributes to positive clinical outcomes. Instrumentation in limited-access anatomic areas like furcation, grooves, deep pockets, concavities, and distal molar areas is technically demanding with traditional mechanical debridement. However, emerging advanced systems such as lasers with bactericidal and detoxification effects offer the benefit of reaching limited-access areas that traditional SRP cannot reach. A digitized search was done on PubMed, Embase, Medline, and Google Scholar using the keywords "lasers","periodontal therapy", "scaling", and "root planing". Upon screening and reviewing, the shortlisted articles comprised narrative reviews, systematic reviews, randomized controlled trials, comparative studies, split-mouth studies, case series, and reports of non-surgical laser therapy and lasers as an adjunct to SRP. This review presents a comprehensive comparative evaluation of different laser modalities utilized in non-surgical periodontal treatment in contrast to standard SRP, rather than an exhaustive article review. It delves into the history and development of lasers, highlighting key advancements made in the realm of periodontics and dental care. This review includes an elucidation of the theory behind laser operation, along with an exploration of its intrinsic characteristics and breakdown of the various types of lasers that are currently available, and an examination of existing literature in both present and historical contexts regarding the comparison of various types of lasers with traditional periodontal treatment.

Antibacterial Effect, ADMET Properties, and Molecular Docking of Morpholine Derivatives with Varying Alkyl Chain Length Against Methicillin Resistant Staphylococcus aureus (MRSA) Isolates

AbstractIn this work, we synthesized a series of nine tetraalkylammonium salts derived from N‐methyl morpholine and assessed their antibacterial efficacy against Methicillin‐Resistant Staphylococcus aureus (MRSA). The investigated morpholinium cations differ by the length of one linear alkyl chain, which ranges from 1 to 18 carbon atoms. We found that compounds with alkyl chains in the n‐C12H25‐(n‐dodecyl) to C16H33‐(n‐hexadecyl) display the highest bactericidal effects, exhibiting Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of 3.9 μg/mL – surpassing the effectiveness of the commercial drug Linezolid. Conversely, compounds with shorter chains (<5 carbon atoms) are inactive against MRSA, establishing a clear structure‐activity relationship. Assays on A. salina reveal that short‐alkyl‐chain morpholinium derivatives, inactive against MRSA), are moderately toxic, while the strongest bactericides of our set demonstrate high or extreme toxicity to A. salina. Our findings underscore the potential of morpholine derivatives as a means to control Methicillin‐Resistant Staphylococcus aureus and pinpoint the need to develop safe applications for these compounds given their potential toxicity.

The need for in-house efficacy testing and assessment of the antimicrobial properties of silver nanoparticle (Ag+)-impregnated showerheads against Pseudomonas aeruginosa intended for healthcare waters in high-risk patient settings

Pseudomonas aeruginosa is a Gram-negative water-borne opportunistic pathogen. Reservoirs of bacteria can infect vulnerable populations. Mitigation of this risk in healthcare includes regular microbiology monitoring and chemical/thermal disinfection of outlets. Where contamination is persistent, point-of-use filters/antimicrobial showers may be used to reduce bioburden. In this study, the efficacy of a silver-impregnated (Ag+) antimicrobial showerhead against P. aeruginosa was tested, under simulated conditions.Test (excised from antimicrobial [Ag+] showerhead) and control (stainless-steel) coupons (∼1cm2; n=108) were inoculated with 10μL (∼103 colony forming units [CFU]) P. aeruginosa (NCTC 10662 and wild-types) and overlaid with coverslips. Coupons were incubated at ambient temperature (∼40% relative humidity) for 0 minutes, 30 minutes, 2 hours, 4 hours, 24 hours. Coupons and coverslips were transferred to neutraliser solution followed by bead washing for bacterial recovery and enumeration.Contamination ranged from ∼2.90-log10 CFU (±0.14-log10; type-strain) to ∼3.02-log10 CFU (±0.16-log10; wild-types). No significant reductions in P. aeruginosa bioburden were observed against either of the three strains (P>0.05). Analogous bacterial decline was noted between the test and control (falling to below the detection limit) between 4-24 hours, possibly due to desiccation.Whilst being an economically and environmentally friendly option, antimicrobial showers may not be appropriate to lessen bioburden in healthcare waters. Previous research has demonstrated the bactericidal effects of silver-ions, however this was not established in our study. Although the concentration of silver in the test materials was unknown, our findings suggest that antimicrobial showerheads may require higher concentrations of silver-ions, to display antimicrobial activity. Further testing is required to determine efficacy against biofilms.

MXene@Fe3O4/PDA nanosheets with photothermal-magnetically coupled antibacterial properties

Pathogenic infections pose a major threat to global public health, and what's worse is that the bacteria in infected places often exist in the form of biofilms, making it impossible for antibiotics and other contact bactericidal substances to penetrate their interior. Therefore, looking for an effective method with synergistic antibacterial and biofilm removal properties is a key challenge. A kind of magnetic MXene@Fe3O4/PDA nanosheets with antibacterial properties of photothermal magnetic coupling are reported in this paper. Fe3O4 was grown in situ on MXene nanosheets and then coated with a layer of polydopamine (PDA). MXene@Fe3O4/PDA nanosheet (120 μg/mL) showed an over 95% inhibition rate against E. coli and S. aureus under 808 nm laser irradiation. In addition, peroxidase-like activity can produce reactive oxygen species. The photothermal antibacterial properties were further enhanced under the action of rotating magnetic field. The antibacterial activity was increased to close to 99.99%, and the removal effect of biofilm was also very good. The photothermal and magnetic coupled antibacterial effects can reduce the amount of MXene@Fe3O4/PDA, thus it is expected to reduce the damage caused by overheating normal tissues and is safer than pure photothermal therapy.

Polyacrylamide/Gel-based Self-healing Artificial Tympanic Membrane for Drug Delivery of Otitis Treatment

Polyacrylamide/Gel-based Self-healing Artificial Tympanic Membrane for Drug Delivery of Otitis Treatment

Biocompatibility and Antibacterial Properties of NiTiAg Porous Alloys for Bone Implants.

In order to reduce infections, porous NiTi alloys with 62% porosity were obtained by self-propagating high-temperature synthesis with the addition of 0.2 and 0.5 at. % silver nanoparticles. Silver significantly improved the alloys' antibacterial activity without compromising cytocompatibility. An alloy with 0.5 at. % Ag showed the best antibacterial ability against Staphylococcus epidermidis. All alloys exhibited good biocompatibility with no cellular toxicity against embryonic fibroblast 3T3 cells. Clinical evaluation of the results after implantation showed a complete absence of purulent-inflammatory complications in all animals. Even distribution of silver nanoparticles in the surface layer of the porous NiTi alloy provides a uniform antibacterial effect.

Bactericidal effect of tetracycline in E. coli strain ED1a may be associated with ribosome dysfunction

Ribosomes translate the genetic code into proteins. Recent technical advances have facilitated in situ structural analyses of ribosome functional states inside eukaryotic cells and the minimal bacterium Mycoplasma. However, such analyses of Gram-negative bacteria are lacking, despite their ribosomes being major antimicrobial drug targets. Here we compare two E. coli strains, a lab E. coli K-12 and human gut isolate E. coli ED1a, for which tetracycline exhibits bacteriostatic and bactericidal action, respectively. Using our approach for close-to-native E. coli sample preparation, we assess the two strains by cryo-ET and visualize their ribosomes at high resolution in situ. Upon tetracycline treatment, these exhibit virtually identical drug binding sites, yet the conformation distribution of ribosomal complexes differs. While K-12 retains ribosomes in a translation-competent state, tRNAs are lost in the vast majority of ED1a ribosomes. These structural findings together with the proteome-wide abundance and thermal stability assessments indicate that antibiotic responses are complex in cells and can differ between different strains of a single species, thus arguing that all relevant bacterial strains should be analyzed in situ when addressing antibiotic mode of action.

Efficacy of ceftazidime/avibactam and plazomicin on carbapenem-resistant Klebsiella pneumoniae and Escherichia coli.

Carbapenem-resistant Enterobacterales (CRE) have become a major public health problem worldwide. The aim of this study was to investigate efficacy of ceftazidime/avibactam and plazomicin on carbapenem-resistant Klebsiella pneumoniae and Escherichia coli isolates. Susceptibility of imipenem, meropenem, ertapenem, ceftazidime/avibactam and plazomicin was investigated by broth-microdilution method. Major carbapenemases NDM, VIM, IMP, KPC, OXA-48 as well as other β-lactamases namely, TEM, SHV, OXA-1-like, CTX-M, ACC, FOX, MOX, DHA, CIT, EBC, VEB, GES, PER were investigated by PCR. A total of 120 carbapenem-resistant isolates (60 E. coli and 60 K. pneumoniae) were included in this study and blaOXA-48-like was found in 78.33%, blaNDM in 26.66%, blaKPC in 7.5%, blaIMP in 5.83%, and blaVIM in 5%. Among 94 isolates with the blaOXA-48-like gene, 22.3% were resistant to ceftazidime/avibactam and 51.1% were resistant to plazomicin. Of 32 isolates with blaNDM, 31 (96.9%) were resistant to ceftazidime/avibactam and 30 (93.75%) were resistant to plazomicin, and both antibiotics had limited effects against blaNDM carriers (P < 0.001). Of the 12 isolates with blaNDM+OXA-48 combination, 11 (91.7%) were resistant to ceftazidime/avibactam and plazomicin. The effect of both antibiotics was significantly lower in strains with blaNDM+OXA-48 combination (P < 0.005).The most common carbapenemase genes in this study were blaOXA-48-like and blaNDM. Ceftazidime/avibactam demonstrated a good efficacy among OXA-48 producing K. pneumoniae and E. coli, however, plazomicin had a significantly lower antibacterial effect in our study. Both antimicrobial agents should be considered as an option by evaluating combined susceptibility results and gene patterns obtained by regional and global molecular data in the treatment of CRE infections.

Synthesis, Antibacterial Activity and In Silico Study of 1-(2-ethyl acetate)- 2-styryl 5-nitroimidazole Derivatives

Background: For more than six decades, the use of metronidazole has been limited to anaerobic microorganisms. However, there are accounts of metronidazole derivatives exhibiting strong effectiveness against facultative anaerobic bacteria, suggesting that there may be another mechanism of action for metronidazole. Recent studies have shown that the enzyme FabH (β-ketoacyl-acyl carrier protein synthase III), responsible for the first step of fatty acid biosynthesis (FAB), is a promising target for nitroimidazole derivatives that can be used as an effective anti-infective agent. Objective: This study aimed to synthesize 1-(2-ethyl acetate)-2-styryl nitroimidazole derivatives and evaluate their in vitro and in silico antibacterial activity Methods: We synthesized 2-styryl 5-nitroimidazole derivatives by first condensing metronidazole with benzaldehydes and then carrying out an acetylation reaction. We evaluated the antimicrobial activity of the synthesized compounds against three Gram-positive bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus agalactiae) and three Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) using a two-fold serial dilution MTT (3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide) assay. Results: Compounds 2 and 4 exhibited the highest level of antibacterial effectiveness, with minimum inhibitory concentrations (MIC) of 1.56 μg/mL against S. agalactiae and 3.13 μg/mL against P. aeruginosa. Compounds 2 and 4 also exhibited potent activity against K. pneumonia, with an MIC value of 6.25 μg/mL and 12.5 μg/mL, respectively. Molecular docking studies revealed that both compounds have favorable hydrophobic and electrostatic interactions with conserved residues in the binding site of the E. coli β-Ketoacyl-acyl carrier protein synthase III (FabH) complex. Conclusion: Acetylation of 2-styryl-5-nitroimidazoles improved both their biological activity and binding interaction with the target protein

Antibacterial and antibiofilm activity of mint leaves (Mentha piperita L) extracts against Streptococcus mutans UA159: a laboratory experiment

Introduction: Oral health is a major concern in healthcare worldwide, with dental caries being a prevalent issue among children and adults. Streptococcus mutans is a primary bacterium implicated in the development of dental caries due to its acidogenic nature. Mint leaf (Mentha piperita L.) is a unique herbal plant that has antibacterial and antibiofilm properties against S. mutans and minimal side effects. The purpose of this study was to analyze the antibacterial effectiveness of mint leaf against the growth of S. mutans UA159 and its antibiofilm effects. Methods: This study was conducted experimentally with the posttest-only control group design, using the broth microdilution method in 6 test groups, namely mint leaf extract with a concentration of 3.125, 6.25, 12.5, 25, 50, and 100% and also two control groups, namely the negative control using aquadest and the positive control using 0.2% chlorhexidine. Biofilm growth is determined by comparing Optical Density (OD) values and then calculating the percentage of eradication of S. mutans biofilm formation. Results: The results indicated that the mint leaf extract exhibited antibacterial effects against S. mutans, with the largest inhibition zone diameter observed at a 100% concentration. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)90 values using the broth microdilution method in this study were 12.5% and 100% concentrations, respectively. Mint leaf extract has been shown to significantly inhibit the growth of S. mutans (p&lt;0.05). The results of the inhibition test on biofilm formation at a concentration of 100% averaged 87.39%. Conclusion: Mint leaf extract has an antibacterial and antibiofilm effect on the growth of S. mutans. The level of inhibition of mint leaf extract on the growth of S. mutans is proportional to its concentration; the higher the concentration of the extract, the stronger the inhibitory ability.KeywordAnti-Bacterial agents, biofilms, Mentha piperita, oral health, Streptococcus mutans.

In Silico Design and in Vitro Assessment of Bicyclic Trifluoromethylated Pyrroles as New Antibacterial and Antifungal Agents.

QSAR studies on the number of compounds tested as S. aureus inhibitors were performed using an interactive Online Chemical Database and Modeling Environment (OCHEM) web platform. The predictive ability of the developed consensus QSAR model was q2 = 0.79 ± 0.02. The consensus prediction for the external evaluation set afforded high predictive power (q2 = 0.82 ± 0.03). The models were applied to screen a virtual chemical library with anti-S. aureus activity. Six promising new bicyclic trifluoromethylated pyrroles were identified, synthesized and evaluated in vitro against S. aureus, E. coli, and A. baumannii for their antibacterial activity and against C. albicans, C. krusei and C. glabrata for their antifungal activity. The synthesized compounds were characterized by 1H, 19F, and 13C NMR and elemental analysis. The antimicrobial activity assessment indicated that trifluoromethylated pyrroles 9 and 11 demonstrated the greatest antibacterial and antifungal effects against all the tested pathogens, especially against multidrug-resistant strains. The acute toxicity of the compounds to Daphnia magna ranged from 1.21 to 33.39 mg/L (moderately and slightly toxic). Based on the docking results, it can be suggested that the antibacterial and antifungal effects of the compounds can be explained by the inhibition of bacterial wall component synthesis.

Mechanisms of Triton X-100 reducing the Ag+-resistance of Enterococcus faecalis.

To investigate the mechanism of Triton X-100 (TX-100) reducing the Ag+-resistance of Enterococcus faecalis (E. faecalis), and evaluate the antibacterial effect of TX-100+Ag+ against the induced Ag+-resistant E. faecalis (AREf). The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of AgNO3 against E. faecalis with/without TX-100 were determined to verify the enhanced antibacterial activity. Transmission electron microscopy (TEM) was used to observe the morphological changes of E. faecalis after treatment. The intra- and extracellular concentration of Ag+ in treated E. faecalis was evaluated using inductively coupled plasma mass spectrometer (ICP-MS). The changes in cell membrane potential and integrity of treated E. faecalis were also observed using the flow cytometer. Moreover, AREf was induced through continuous exposure to sub-MIC of Ag+ and the antibacterial effect of TX-100+Ag+ on AREf was further evaluated. The addition of 0.04% TX-100 showed maximal enhanced antibacterial effect of Ag+ against E. faecalis. The TEM and ICP-MS results demonstrated that TX-100 could facilitate Ag+ to enter E. faecalis through changing the membrane structure and integrity. Flow cytometry further showed the effect of TX-100 on membrane potential and permeability of E. faecalis. In addition, the enhanced antibacterial effect of TX-100+Ag+ was also confirmed on induced AREf. TX-100 can facilitate Ag+ to enter E. faecalis through disrupting the membrane structure and changing the membrane potential and permeability, thus reducing the Ag+-resistance of E. faecalis and enhancing the antibacterial effect against either normal E. faecalis or induced AREf.