Antibacterial Effect of Chitosan–Gold Nanoparticles and Computational Modeling of the Interaction between Chitosan and a Lipid Bilayer Model

Pathogenic bacteria have the ability to develop antibiotic resistance mechanisms. Their action consists mainly in the production of bacterial enzymes that inactivate antibiotics or the appearance of modifications that prevent the arrival of the drug at the target point or the alteration of the target point itself, becoming a growing problem for health systems. Chitosan–gold nanoparticles (Cs-AuNPs) have been shown as effective bactericidal materials avoiding damage to human cells. In this work, Cs-AuNPs were synthesized using chitosan as the reducing agent, and a systematic analysis of the influence of the synthesis parameters on the size and zeta potential of the Cs-AuNPs and their UV-vis spectra was carried out. We used a simulation model to characterize the interaction of chitosan with bacterial membranes, using a symmetric charged bilayer and two different chitosan models with different degrees of the chitosan amine protonation as a function of pH, with the aim to elucidate the antibacterial mechanism involving the cell wall disruption. The Cs-AuNP antibacterial activity was evaluated to check the simulation model.

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Two-Step Triethylamine-Based Synthesis of MgO Nanoparticles and Their Antibacterial Effect against Pathogenic Bacteria

Nanomaterials ◽

10.3390/nano11020410 ◽

2021 ◽

Vol 11 (2) ◽

pp. 410

Author(s):

Ramiro Muñiz Diaz ◽

Pablo Eduardo Cardoso-Avila ◽

José Antonio Pérez Tavares ◽

Rita Patakfalvi ◽

Virginia Villa Cruz ◽

...

Keyword(s):

Pathogenic Bacteria ◽

Structural Changes ◽

Antibacterial Effect ◽

Precipitation Method ◽

Gram Positive ◽

Gram Negative ◽

Bacterial Membranes ◽

Force Microscopy ◽

Mean Size ◽

Escherichia Coli Bacteria

Magnesium oxide nanoparticles (MgO NPs) were obtained by the calcination of precursor microparticles (PM) synthesized by a novel triethylamine-based precipitation method. Scanning electron microscopy (SEM) revealed a mean size of 120 nm for the MgO NPs. The results of the characterizations for MgO NPs support the suggestion that our material has the capacity to attack, and have an antibacterial effect against, Gram-negative and Gram-positive bacteria strains. The ability of the MgO NPs to produce reactive oxygen species (ROS), such as superoxide anion radicals (O2•−) or hydrogen peroxide (H2O2), was demonstrated by the corresponding quantitative assays. The MgO antibacterial activity was evaluated against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria, with minimum inhibitory concentrations (MICs) of 250 and 500 ppm on the microdilution assays, respectively. Structural changes in the bacteria, such as membrane collapse; surface changes, such as vesicular formation; and changes in the longitudinal and horizontal sizes, as well as the circumference, were observed using atomic force microscopy (AFM). The lipidic peroxidation of the bacterial membranes was quantified, and finally, a bactericidal mechanism for the MgO NPs was also proposed.

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The Antibacterial Effect of Bacteriophage-Like Gold Nanoparticles

NANO ◽

10.1142/s1793292021500752 ◽

2021 ◽

pp. 2150075

Author(s):

Xiuzhen Huang ◽

Benben Lu ◽

Yingxian Zhao ◽

Zhiqiang Wang ◽

Hongwei Wang ◽

...

Keyword(s):

Gold Nanoparticles ◽

Pathogenic Bacteria ◽

Near Infrared ◽

Antibacterial Effect ◽

Environmental Engineering ◽

Oxygen Species ◽

Surrounding Environment ◽

Low Concentrations ◽

Effective Inhibition

The growth of pathogenic bacteria seriously threatens human health. Effective inhibition of pathogenic bacteria in the human body and the surrounding environment is of great urgency. In this work, we propose a strategy in preparing bacteriophage-like gold nanoparticles (B-AuNPs) for antibacterial applications. B-AuNPs were prepared by multiple in-situ reducing reactions on the surface of AuNPs. It was shown that the secondary-reduced AuNPs (B1-AuNPs) have a bacteriophage shaped morphology. Under near infrared laser, B1-AuNPs could almost completely inhibit bacterial growth at low concentrations within 5 min, due to the combined effects of increased temperature and reactive oxygen species (ROS). Moreover, B-AuNPs can be easily separated from the dead bacteria and the recycled B-AuNPs remain the high antibacterial efficiency. It is concluded that B-AuNPs have great potentials in the antibacterial researches for biocontrol, biomedicine and environmental engineering.

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Antibiotics Application Strategies to Control Biofilm Formation in Pathogenic Bacteria

Current Pharmaceutical Biotechnology ◽

10.2174/1389201020666191112155905 ◽

2020 ◽

Vol 21 (4) ◽

pp. 270-286 ◽

Cited By ~ 2

Author(s):

Fazlurrahman Khan ◽

Dung T.N. Pham ◽

Sandra F. Oloketuyi ◽

Young-Mog Kim

Keyword(s):

Biofilm Formation ◽

Pathogenic Bacteria ◽

Extracellular Polymeric Substances ◽

Quorum Quenching ◽

Resistance Mechanisms ◽

Bacterial Biofilm ◽

Bacterial Cells ◽

High Concentration ◽

Biofilm Inhibition ◽

Abiotic Surfaces

Background: The establishment of a biofilm by most pathogenic bacteria has been known as one of the resistance mechanisms against antibiotics. A biofilm is a structural component where the bacterial community adheres to the biotic or abiotic surfaces by the help of Extracellular Polymeric Substances (EPS) produced by bacterial cells. The biofilm matrix possesses the ability to resist several adverse environmental factors, including the effect of antibiotics. Therefore, the resistance of bacterial biofilm-forming cells could be increased up to 1000 times than the planktonic cells, hence requiring a significantly high concentration of antibiotics for treatment. Methods: Up to the present, several methodologies employing antibiotics as an anti-biofilm, antivirulence or quorum quenching agent have been developed for biofilm inhibition and eradication of a pre-formed mature biofilm. Results: Among the anti-biofilm strategies being tested, the sub-minimal inhibitory concentration of several antibiotics either alone or in combination has been shown to inhibit biofilm formation and down-regulate the production of virulence factors. The combinatorial strategies include (1) combination of multiple antibiotics, (2) combination of antibiotics with non-antibiotic agents and (3) loading of antibiotics onto a carrier. Conclusion: The present review paper describes the role of several antibiotics as biofilm inhibitors and also the alternative strategies adopted for applications in eradicating and inhibiting the formation of biofilm by pathogenic bacteria.

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Antimicrobial properties of actively purified secondary metabolites isolated from different marine organisms

Current Pharmaceutical Biotechnology ◽

10.2174/1389201021666200730144536 ◽

2020 ◽

Vol 21 ◽

Author(s):

Nilushi Indika Bamunu Arachchige ◽

Fazlurrahman Khan ◽

Young-Mog Kim

Keyword(s):

Secondary Metabolites ◽

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Bacterial Species ◽

Antimicrobial Properties ◽

Antimicrobial Effect ◽

Cost Effective ◽

Resistance Mechanisms ◽

Marine Organisms ◽

Antimicrobial Compounds

Background: The treatment of infection caused by pathogenic bacteria becomes one of the serious concerns globally. The failure in the treatment was found due to the exhibition of multiple resistance mechanisms against the antimicrobial agents. Emergence of resistant bacterial species has also been observed due to prolong treatment using conventional antibiotics. To combat these problems, several alternative strategies have been employed using biological and chemically synthesized compounds as antibacterial agents. Marine organisms considered as one of the potential sources for the isolation of bioactive compounds due to the easily available, cost-effective, and eco-friendly. Methods: The online search methodology was adapted for the collection of information related to the antimicrobial properties of marine-derived compounds. These compound has been isolated and purified by different purification techniques, and their structure also characterized. Furthermore, the antibacterial activities have been reported by using broth microdilution as well as disc diffusion assays. Results: The present review paper describes the antimicrobial effect of diverse secondary metabolites which are isolated and purified from the different marine organisms. The structural elucidation of each secondary metabolite has also been done in the present paper, which will help for the in silico designing of the novel and potent antimicrobial compounds. Conclusion: A thorough literature search has been made and summarizes the list of antimicrobial compounds that are isolated from both prokaryotic and eukaryotic marine organisms. The information obtained from the present paper will be helpful for the application of marine compounds as antimicrobial agents against different antibiotic-resistant human pathogenic bacteria.

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Varied-shaped gold nanoparticles with nanogram killing efficiency as potential antimicrobial surface coatings for the medical devices

Scientific Reports ◽

10.1038/s41598-021-91847-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ewelina Piktel ◽

Łukasz Suprewicz ◽

Joanna Depciuch ◽

Sylwia Chmielewska ◽

Karol Skłodowski ◽

...

Keyword(s):

Gold Nanoparticles ◽

Medical Devices ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Antimicrobial Spectrum ◽

Antimicrobial Coatings ◽

Low Toxicity ◽

Spherical Gold Nanoparticles ◽

Cost Efficient ◽

Bactericidal Efficiency

AbstractMedical device-associated infections are a serious medical threat, particularly for patients with impaired mobility and/or advanced age. Despite a variety of antimicrobial coatings for medical devices being explored to date, only a limited number have been introduced for clinical use. Research into new bactericidal agents with the ability to eradicate pathogens, limit biofilm formation, and exhibit satisfactory biocompatibility, is therefore necessary and urgent. In this study, a series of varied-morphology gold nanoparticles in shapes of rods, peanuts, stars and spherical-like, porous ones with potent antibacterial activity were synthesized and thoroughly tested against spectrum of Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus clinical strains, as well as spectrum of uropathogenic Escherichia coli isolates. The optimization of gold nanoparticles synthesis allowed to develop nanomaterials, which are proved to be significantly more potent against tested microbes compared with the gold nanoformulations reported to date. Notably, their antimicrobial spectrum includes strains with different drug resistance mechanisms. Facile and cost-efficient synthesis of gold nanoparticles, remarkable bactericidal efficiency at nanogram doses, and low toxicity, underline their potential for development as a new coatings, as indicated by the example of urological catheters. The presented research fills a gap in microbial studies of non-spherical gold nanoparticles for the development of antimicrobial coatings targeting multidrug-resistant pathogens responsible for device-associated nosocomial infections.

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Structural and functional insights into esterase-mediated macrolide resistance

Nature Communications ◽

10.1038/s41467-021-22016-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Michał Zieliński ◽

Jaeok Park ◽

Barry Sleno ◽

Albert M. Berghuis

Keyword(s):

Active Site ◽

Pathogenic Bacteria ◽

Catalytic Mechanism ◽

Three Dimensional ◽

Resistance Mechanisms ◽

Docking Studies ◽

Macrolide Resistance ◽

Flexible Docking ◽

Sequence Identity ◽

Substrate Spectrum

AbstractMacrolides are a class of antibiotics widely used in both medicine and agriculture. Unsurprisingly, as a consequence of their exensive usage a plethora of resistance mechanisms have been encountered in pathogenic bacteria. One of these resistance mechanisms entails the enzymatic cleavage of the macrolides’ macrolactone ring by erythromycin esterases (Eres). The most frequently identified Ere enzyme is EreA, which confers resistance to the majority of clinically used macrolides. Despite the role Eres play in macrolide resistance, research into this family enzymes has been sparse. Here, we report the first three-dimensional structures of an erythromycin esterase, EreC. EreC is an extremely close homologue of EreA, displaying more than 90% sequence identity. Two structures of this enzyme, in conjunction with in silico flexible docking studies and previously reported mutagenesis data allowed for the proposal of a detailed catalytic mechanism for the Ere family of enzymes, labeling them as metal-independent hydrolases. Also presented are substrate spectrum assays for different members of the Ere family. The results from these assays together with an examination of residue conservation for the macrolide binding site in Eres, suggests two distinct active site archetypes within the Ere enzyme family.

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Sorting out the Superbugs: Potential of Sortase A Inhibitors among Other Antimicrobial Strategies to Tackle the Problem of Antibiotic Resistance

Antibiotics ◽

10.3390/antibiotics10020164 ◽

2021 ◽

Vol 10 (2) ◽

pp. 164 ◽

Cited By ~ 1

Author(s):

Nikita Zrelovs ◽

Viktorija Kurbatska ◽

Zhanna Rudevica ◽

Ainars Leonchiks ◽

Davids Fridmanis

Keyword(s):

Cell Wall ◽

Antibiotic Resistance ◽

Pathogenic Bacteria ◽

Resistance Mechanisms ◽

Surface Proteins ◽

Sortase A ◽

Inhibitory Compounds ◽

Alternative Means ◽

Alternative Approaches ◽

Conventional Antibiotics

Rapid spread of antibiotic resistance throughout the kingdom bacteria is inevitably bringing humanity towards the “post-antibiotic” era. The emergence of so-called “superbugs”—pathogen strains that develop resistance to multiple conventional antibiotics—is urging researchers around the globe to work on the development or perfecting of alternative means of tackling the pathogenic bacteria infections. Although various conceptually different approaches are being considered, each comes with its advantages and drawbacks. While drug-resistant pathogens are undoubtedly represented by both Gram(+) and Gram(−) bacteria, possible target spectrum across the proposed alternative approaches of tackling them is variable. Numerous anti-virulence strategies aimed at reducing the pathogenicity of target bacteria rather than eliminating them are being considered among such alternative approaches. Sortase A (SrtA) is a membrane-associated cysteine protease that catalyzes a cell wall sorting reaction by which surface proteins, including virulence factors, are anchored to the bacterial cell wall of Gram(+) bacteria. Although SrtA inhibition seems perspective among the Gram-positive pathogen-targeted antivirulence strategies, it still remains less popular than other alternatives. A decrease in virulence due to inactivation of SrtA activity has been extensively studied in Staphylococcus aureus, but it has also been demonstrated in other Gram(+) species. In this manuscript, results of past studies on the discovery of novel SrtA inhibitory compounds and evaluation of their potency were summarized and commented on. Here, we discussed the rationale behind the inhibition of SrtA, raised some concerns on the comparability of the results from different studies, and touched upon the possible resistance mechanisms as a response to implementation of such therapy in practice. The goal of this article is to encourage further studies of SrtA inhibitory compounds.

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Antibacterial Compounds from Mushrooms: A Lead to Fight ESKAPEE Pathogenic Bacteria?

Planta Medica ◽

10.1055/a-1266-6980 ◽

2020 ◽

Author(s):

Violette Hamers ◽

Clément Huguet ◽

Mélanie Bourjot ◽

Aurélie Urbain

Keyword(s):

Antibiotic Resistance ◽

Global Health ◽

Pathogenic Bacteria ◽

Resistance Mechanisms ◽

Pathogenic Microorganisms ◽

Bacterial Strains ◽

Antibacterial Compounds ◽

New Antibiotics ◽

Hospital Stays ◽

Antibacterial Potential

AbstractInfectious diseases are among the greatest threats to global health in the 21st century, and one critical concern is due to antibiotic resistance developed by an increasing number of bacterial strains. New resistance mechanisms are emerging with many infections becoming more and more difficult if not impossible to treat. This growing phenomenon not only is associated with increased mortality but also with longer hospital stays and higher medical costs. For these reasons, there is an urgent need to find new antibiotics targeting pathogenic microorganisms such as ESKAPEE bacteria. Most of currently approved antibiotics are derived from microorganisms, but higher fungi could constitute an alternative and remarkable reservoir of anti-infectious compounds. For instance, pleuromutilins constitute the first class of antibiotics derived from mushrooms. However, macromycetes still represent a largely unexplored source. Publications reporting the antibacterial potential of mushroom extracts are emerging, but few purified compounds have been evaluated for their bioactivity on pathogenic bacterial strains. Therefore, the aim of this review is to compile up-to-date data about natural products isolated from fruiting body fungi, which significantly inhibit the growth of ESKAPEE pathogenic bacteria. When available, data regarding modes of action and cytotoxicity, mandatory when considering a possible drug development, have been discussed in order to highlight the most promising compounds.

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Selective point-of-care detection of pathogenic bacteria using sialic acid functionalized gold nanoparticles

Talanta ◽

10.1016/j.talanta.2021.122644 ◽

2021 ◽

pp. 122644

Author(s):

Guillermo Landa ◽

Laura G. Miranda-Calderón ◽

Victor Sebastian ◽

Silvia Irusta ◽

Gracia Mendoza ◽

...

Keyword(s):

Gold Nanoparticles ◽

Sialic Acid ◽

Pathogenic Bacteria ◽

Point Of Care ◽

Functionalized Gold Nanoparticles ◽

Point Of Care Detection

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Comparative Evaluation of the Sterilization Effect of Six Kinds of Commercial Disinfectants against Four Pathogenic Bacteria

10.21203/rs.3.rs-652081/v1 ◽

2021 ◽

Author(s):

Wenxia Wang ◽

Xiaoting Liang ◽

Junxia Zheng ◽

Qi He

Keyword(s):

Sodium Hypochlorite ◽

Peracetic Acid ◽

Pathogenic Bacteria ◽

Antibacterial Effect ◽

Antibacterial Properties ◽

Water Soluble ◽

Absolute Ethanol ◽

Dilution Method ◽

Clostridium Sporogenes ◽

Sterilization Effect

Abstract In this work, we systematically investigate the sterilization effect of six kinds of commonly used commercial disinfectants, including the DuPont Virkon disinfectant, peracetic acid disinfectant, sodium hypochlorite, bromogeramine disinfectant, water-soluble allicin, and absolute ethanol, against the Escherichia coli, Staphylococcus aureus, Monilia albican and Clostridium sporogenes. The inhibition zone was used to qualitatively determine the antibacterial effects of the six disinfectants, and then the minimum two-fold dilution method was used to quantitatively determine the minimum inhibitory concentration and minimum bactericidal concentration of the six disinfectants on the four pathogens. The result illustrated that the antibacterial effect of peracetic acid disinfectant is the best, and clostridium sporogenes is the most sensitive to it, followed by bromogermine disinfectant, which can inhibit the four pathogenic bacteria at the concentration recommended by the manufacturer. The antibacterial effect of DuPont Virkon disinfectant, sodium hypochlorite, water-soluble allicin and absolute ethanol is not as good as expected, and cannot inhibit the four kinds of pathogenic bacteria at the recommended concentration. In summary, the antibacterial effect of peracetic acid disinfectant is the strongest, followed by the bromogermine disinfectant, DuPont Virkon disinfectant, sodium hypochlorite and water-soluble allicin. The absolute ethanol exhibits the worst antibacterial properties.

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