scholarly journals BioSAXS measurements reveal that two antimicrobial peptides induce similar molecular changes in Gram-negative and Gram-positive bacteria

2019 ◽  
Author(s):  
A.R. von Gundlach ◽  
M. Ashby ◽  
J. Gani ◽  
P. M. Lopez-Perez ◽  
A. Cookson ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Mode Of Action ◽  
Bacterial Load ◽  
Ultrastructural Changes ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria

AbstractTwo highly active short broad-spectrum AMPs (14D and 69D) with unknown mode of action have been investigated in regards to their effect against the Gram-negative bacteriaE. coliand the Gram-positive bacteria methicillin-resistantStaphylococcus aureus(MRSA). Minimal inhibitory concentration (MIC) measurements using a cell density of 108cfu/ml resulted in values between 16 and 32 μg/ml. Time kill experiments using 108cfu/ml revealed complete killing, except for 69D in combination with MRSA, where bacterial load was reduced a million times. Small angle X-ray scattering of biological samples (BioSAXS) at 108cfu/ml was applied to investigate the ultrastructural changes inE. coliand MRSA in response to these two broad-spectrum AMPs. In addition, electron microscopy (EM) was performed to visualize the treated and non-treated bacteria. As expected, the scattering curves generated using BioSAXS show the ultrastructure of the Gram-positive and Gram-negative bacteria to be very different (BioSAXS is not susceptible to the outer shape). After treatment with either peptide, the scattering curves ofE. coliand MRSA cells are much more alike. This data in conjunction with the EM indicates that ribosomes might be effected by the treatment as well as changes in the nucleoid occurs. Whereas in EM it is notoriously difficult to observe changes for spherical Gram-positives, the BioSAXS results are superior and reveal strongly similar effects for both peptides induced in Gram-positive as well as Gram-negative bacteria. Given the high-throughput possibility and robust statistics BioSAXS can support and speed up mode of action research in AMPs and other antimicrobial compounds, making a contribution towards the development of urgently needed drugs against resistant bacteria.

scholarly journals Water-dispersible glycosylated poly(2,5′-thienylene)porphyrin-based nanoparticles for antibacterial photodynamic therapy

2019 ◽  
Vol 18 (5) ◽  
pp. 1147-1155 ◽  
Author(s):  
Rehan Khan ◽  
Melis Özkan ◽  
Aisan Khaligh ◽  
Dönüs Tuncel
Keyword(s):  
Antibacterial Activity ◽  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Water Dispersible ◽  
Gram Positive Bacteria ◽  
High Yields

Water-dispersible glycosylated poly(2,5′-thienylene)porphyrin-based nanoparticles have the ability to generate singlet oxygen in high yields and exhibit light-triggered antibacterial activity against Gram negative bacteria, E. coli as well as Gram positive bacteria, B. subtilis.

scholarly journals Synthesis and Antibacterial Activity of Chalcones and Pyrimidine-2-ones

2005 ◽  
Vol 2 (2) ◽  
pp. 109-112
Author(s):  
A. K. Parekh ◽  
K. K. Desai
Keyword(s):  
Antibacterial Activity ◽  
Spectral Data ◽  
Elemental Analysis ◽  
Aromatic Aldehydes ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
H Nmr

Some new chalcones have been prepared by Claisen-schmidt condensation of ketone and different aromatic aldehydes. These chalcones on condensation with urea in presence of acid gave Pyrimidine-2-ones. The synthesized compounds have been characterized by elemental analysis, IR and1H NMR spectral data. They have been screened for their antibacterial activity against Gram positive bacteria B. subtillis & S. aureus and Gram negative bacteria E. coli & S. typhi.

scholarly journals Different Modes of Action of Naphthyridones in Gram-Positive and Gram-Negative Bacteria

2006 ◽  
Vol 50 (1) ◽  
pp. 385-387 ◽  
Author(s):  
Ed T. Buurman ◽  
Kenneth D. Johnson ◽  
Roxanne K. Kelly ◽  
Kathy MacCormack
Keyword(s):  
Escherichia Coli ◽  
Haemophilus Influenzae ◽  
Mode Of Action ◽  
Bacterial Pathogens ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Modes Of Action

ABSTRACT Naphthyridones that were recently described as a class of translation inhibitors in gram-positive bacteria mediate their mode of action via GyrA in Haemophilus influenzae and Escherichia coli. These are the first examples of compounds in which modes of action in different bacterial pathogens are mediated through widely different targets.

scholarly journals Potential Assessment of Rumex spp. as a Source of Bioactive Compounds and Biological Activity

2021 ◽  
Vol 12 (2) ◽  
pp. 1824-1834
Keyword(s):  
Antioxidant Activity ◽  
Broad Spectrum ◽  
Pathogenic Bacteria ◽  
Gram Negative Bacteria ◽  
Meoh Extract ◽  
Gram Positive ◽  
Filter Paper Disc ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Antibacterial Performance

Secondary metabolites from the shoots and roots of three Rumex species collected from three different habitats were investigated (Rumex dentatus collected from cultivated land, R. pictus collected from the coastal desert and R. vesicarius collected from the inland desert) and tested for antioxidant activity as well as for anti-microbial activity against some human pathogenic bacteria. The present study indicated that the quantitative analysis of shoot and root extracts of three Rumex spp. were found to be rich in tannins and phenolics composition. The aerial parts of the three plants exhibited the highest significant values compared to the root parts. The MeOH extracts of Rumex species showed adequate antioxidant activity, wherein the IC50 values of the MeOH from the cultivated sample was 41.61 and 31.31 mg mL-1, coastal samples were 34.99 and 23.99 mg mL-1, while the sample of inland showed IC50 value of 41.59 and 31.67 mg mL-1, for root and shoot, respectively. Furthermore, using a filter paper disc assay, the MeOH extracts of the three Rumex species showed a substantial anti-microbial inhibitory effect on the growth of 10 pathogenic bacteria. According to sensitivity, the tested organisms could be sequenced as following: E. coli < K. pneumoniae ˂ S. typhi < P. aeruginosa for Gram-negative bacteria and B. subtilis < S. pneumoniae ˂ L. monocytoyenes < S. epidermis < S. aureus < B. cereus for Gram-positive bacteria. In addition, the antibacterial performance of R. dentatus root and R. vesicarius shoot MeOH extract is 100% broad spectrum against Gram-negative bacteria. A shoot of R. dentatus and R. pictus MeOH extract against Gram-positive bacteria is 83.3% broad spectrum. A further study is recommended for more characterization of the major compounds and assesses their efficiency and biosafety.

scholarly journals Molecular Characterization of Zinc (Zn) Resistant Bacteria in Banger River, Pekalongan, Indonesia

2018 ◽  
Vol 10 (3) ◽  
pp. 622-628
Author(s):  
Fitri Arum Sasi ◽  
Hermin Pancasakti Kusumaningrum ◽  
Anto Budiharjo
Keyword(s):  
Bacterial Species ◽  
Selective Medium ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Indigenous Bacteria ◽  
Gram Positive Bacteria ◽  
Sequences Analysis

Indigenous bacteria are able to remove the metals contamination in environment. This study aimed to assess the resistance of bacterial species to Zinc (Zn) in Banger River, Pekalongan City. The bacteria from three different parts of Banger River were isolated and inoculated in Zn-selective medium. Then, molecular identification to determine the bacteria species was conducted using polymerase chain reaction (PCR) by applying forward-reverse 16SrRNA gene primers. The sequences analysis was conducted using MUSCLE and MEGA6. There were seven dominant species that possibly resistant to Zn. Approximately, every isolate could reach more than 95 % from 2000 ppm of Zn in the medium. The higher absorption of Zn was found in Z5 isolate. The seven bacteria species were clustered into nine genera i.e. Klebsiela, Xenorhabdus, Cronobacter, Enterobacter, Escherichia, Shigella and Sporomusa known as Gram Negative bacteria and Clostridium and Bacillus as Gram Positive bacteria. In Gram Positive bacteria, especially Bacillus sp, carboxyl group in peptidoglycan play a role as metal binder. In Gram-negative bacteria, lipopolysaccharide (LPS) which is highly anionic component on the outer membrane, able to catch the Zn. Besides that, Enterobacter activates endogen antioxidants such as glutathione peroxidase (GSHPx), glutathione reductase (GR), catalase (CAT) and superoxide dismutase (SOD). The research found there was possible seven novel indigenous bacteria species in Banger that able to remove Zn from the sediment extremely. This finding can be developed as an eco-friendly approach to reduce metals pollution using local microorganisms.

scholarly journals Mode of action of the 2-phenylquinoline efflux inhibitor PQQ4R againstEscherichia coli

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3168 ◽  
Author(s):  
Diana Machado ◽  
Laura Fernandes ◽  
Sofia S. Costa ◽  
Rolando Cannalire ◽  
Giuseppe Manfroni ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Synergistic Activity ◽  
Dependent Manner ◽  
Gram Negative ◽  
E Coli ◽  
Efflux Pump Inhibitors

Efflux pump inhibitors are of great interest since their use as adjuvants of bacterial chemotherapy can increase the intracellular concentrations of the antibiotics and assist in the battle against the rising of antibiotic-resistant bacteria. In this work, we have described the mode of action of the 2-phenylquinoline efflux inhibitor (4-(2-(piperazin-1-yl)ethoxy)-2-(4-propoxyphenyl) quinolone – PQQ4R), againstEscherichia coli,by studding its efflux inhibitory ability, its synergistic activity in combination with antibiotics, and compared its effects with the inhibitors phenyl-arginine-β-naphthylamide (PAβN) and chlorpromazine (CPZ). The results showed that PQQ4R acts synergistically, in a concentration dependent manner, with antibiotics known to be subject to efflux inE. colireducing their MIC in correlation with the inhibition of their efflux. Real-time fluorometry assays demonstrated that PQQ4R at sub-inhibitory concentrations promote the intracellular accumulation of ethidium bromide inhibiting its efflux similarly to PAβN or CPZ, well-known and described efflux pump inhibitors for Gram-negative bacteria and whose clinical usage is limited by their levels of toxicity at clinical and bacteriological effective concentrations. The time-kill studies showed that PQQ4R, at bactericidal concentrations, has a rapid antimicrobial activity associated with a fast decrease of the intracellular ATP levels. The results also indicated that the mode of action of PQQ4R involves the destabilization of theE. coliinner membrane potential and ATP production impairment, ultimately leading to efflux pump inhibition by interference with the energy required by the efflux systems. At bactericidal concentrations, membrane permeabilization increases and finally ATP is totally depleted leading to cell death. Since drug resistance mediated by the activity of efflux pumps depends largely on the proton motive force (PMF), dissipaters of PMF such as PQQ4R, can be regarded as future adjuvants of conventional therapy againstE. coliand other Gram-negative bacteria, especially their multidrug resistant forms. Their major limitation is the high toxicity for human cells at the concentrations needed to be effective against bacteria. Their future molecular optimization to improve the efflux inhibitory properties and reduce relative toxicity will optimize their potential for clinical usage against multi-drug resistant bacterial infections due to efflux.

scholarly journals Development of Methionyl-tRNA Synthetase Inhibitors as Antibiotics for Gram-Positive Bacterial Infections

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Omeed Faghih ◽  
Zhongsheng Zhang ◽  
Ranae M. Ranade ◽  
J. Robert Gillespie ◽  
Sharon A. Creason ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Bacterial Species ◽  
Bacterial Load ◽  
Trna Synthetase ◽  
Resistant Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Methionyl Trna Synthetase

ABSTRACT Antibiotic-resistant bacteria are widespread and pose a growing threat to human health. New antibiotics acting by novel mechanisms of action are needed to address this challenge. The bacterial methionyl-tRNA synthetase (MetRS) enzyme is essential for protein synthesis, and the type found in Gram-positive bacteria is substantially different from its counterpart found in the mammalian cytoplasm. Both previously published and new selective inhibitors were shown to be highly active against Gram-positive bacteria with MICs of ≤1.3 μg/ml against Staphylococcus, Enterococcus, and Streptococcus strains. Incorporation of radioactive precursors demonstrated that the mechanism of activity was due to the inhibition of protein synthesis. Little activity against Gram-negative bacteria was observed, consistent with the fact that Gram-negative bacterial species contain a different type of MetRS enzyme. The ratio of the MIC to the minimum bactericidal concentration (MBC) was consistent with a bacteriostatic mechanism. The level of protein binding of the compounds was high (>95%), and this translated to a substantial increase in MICs when the compounds were tested in the presence of serum. Despite this, the compounds were very active when they were tested in a Staphylococcus aureus murine thigh infection model. Compounds 1717 and 2144, given by oral gavage, resulted in 3- to 4-log decreases in the bacterial load compared to that in vehicle-treated mice, which was comparable to the results observed with the comparator drugs, vancomycin and linezolid. In summary, the research describes MetRS inhibitors with oral bioavailability that represent a class of compounds acting by a novel mechanism with excellent potential for clinical development.

scholarly journals Categorization of Bacterial Pathogens Present in Infected Wounds and their Antibiotic Resistance Profile Recovered from Patients Attending Rizgary Hospital-Erbil

2021 ◽  
Vol 9 (2) ◽  
pp. 64-70
Author(s):  
Ahmed A. Al-Naqshbandi ◽  
Hedy A. Hassan ◽  
Mahmoud A. Chawsheen ◽  
Haval H. Abdul Qader
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Staphylococcus Epidermidis ◽  
Resistant Bacteria ◽  
Antibiotic Prescribing ◽  
Gram Negative Bacteria ◽  
Wound Infections ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Wound infection with antibiotic-resistant bacteria can extend a patients’ debility and increase the expense of treatment in the long term; therefore, careful management of patients with wound infections is necessary to avoid complications. The usage of antimicrobial agent is a major factor in resistance development. This study aims to understand the causes of wound infections, as well as the criteria for diagnosing them for more sensible antibiotic prescribing. Samples from 269 wound patients were collected, and cultured for bacterial growth. Gram stain technique, bacterial identification via VITEK 2 compact system were investigated in this study. Gram negative bacteria accounted for 59.15% of the total isolates, while pathogenic gram positive bacteria accounted for 40.85% of total isolates. Escherichia coli and Pseudomonas aeruginosa are the dominant pathogenic gram negative bacteria in wounds, while Staphylococcus aureus, and Staphylococcus epidermidis are the dominant pathogenic gram positive bacteria. Pseudomonas aeruginosa showed 100% resistance to the majority of antibiotic tested, including Ampicillin, Amoxicillin/Clavulanic Acid, Aztreona, Ceftriaxone, and others. Staphylococcus aureus and Staphylococcus epidermidis are 100% resistant to Ampicillin, Ceftriaxone, and Cefotaxime. For more efficient antibiotic prescriptions, the causative microorganisms, and their current susceptibility patterns need to be mandated for testing before prescribing any antibiotics to patients. Prescriptions are frequently based solely on general information about the antibiotic's function, rather than on individual response variation to the pathogen and the antibiotic. Particularly when the common pathogens in this study show multidrug resistance in wounds.

scholarly journals In VitroAntimicrobial Activity and Effect on Biofilm Production of a White Grape Juice (Vitis vinifera) Extract

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Angela Filocamo ◽  
Carlo Bisignano ◽  
Giuseppina Mandalari ◽  
Michele Navarra
Keyword(s):  
Aspergillus Niger ◽  
Grape Juice ◽  
Antimicrobial Effect ◽  
Gram Negative Bacteria ◽  
Respiratory Pathogens ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria

Background. The aim of the present study was to evaluate the antimicrobial effect of a white grape juice extract (WGJe) against a range of Gram-positive and Gram-negative bacteria, yeasts, and the fungusAspergillus niger. WGJe was also tested on the production of bacterial biofilmsin vitro.Results. WGJe inhibitedin vitromost Gram-positive bacteria tested,Staphylococcus aureusATCC 6538P being the most sensitive strain (MIC values of 3.9 μg/mL). The effect was bactericidal at the concentration of 500 μg/mL. Amongst the Gram-negative bacteria,Escherichia coliwas the only susceptible strain (MIC and MBC of 2000 μg/mL). No effect on the growth ofCandidasp. and the fungusAspergillus nigerwas detected (MIC values > 2000 μg/mL). WGJe inhibited the biofilms formation ofE. coliandPseudomonas aeruginosawith a dose-dependent effect.Conclusions. WGJe exerted both bacteriostatic and bactericidal activityin vitro. The presented results could be used to develop novel strategies for the treatment of skin infections and against potential respiratory pathogens.

scholarly journals Identification of Ly2 members as antimicrobial peptides from zebrafish Danio rerio

2017 ◽  
Vol 37 (1) ◽  
Author(s):  
Xuemin Liu ◽  
Xuwen Cao ◽  
Su Wang ◽  
Guangdong Ji ◽  
Shicui Zhang ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Recombinant Proteins ◽  
Mammalian Cells ◽  
Multidrug Resistant ◽  
Scatchard Analysis ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria

The emergence of multidrug-resistant (MDR) microbes caused by overuse of antibiotics leads to urgent demands for novel antibiotics exploration. Our recent data showed that Ly2.1–3 (a novel lymphocyte antigen 6 (Ly6) gene cluster) were proteins with cationic nature and rich in cysteine content, that are characteristic of antimicrobial peptides (AMPs) and their expression were all significantly up-regulated after challenge with lipopolysaccharide (LPS). These strongly suggested that Ly2.1–3 are potential AMPs, but firm evidence are lacking. Here, we clearly showed that the recombinant proteins of Ly2.1–3 were capable of killing Gram-negative bacteria Aeromonas hydrophila and Escherichia coli, while they had little bactericidal activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis. We also showed that recombinant proteins Ly2.1–3 (rLy2.1–3) were able to bind to the Gram-negative bacteria A. hydrophila, E. coli and the microbial signature molecule LPS, but not to the Gram-positive bacteria S. aureus and B. subtilis as well as the microbial signature molecule LTA. Moreover, the Scatchard analysis revealed that rLy2.1–3 could specifically bind to LPS. Finally, we found that Ly2.1–3 were not cytotoxic to mammalian cells. All these together indicate that Ly2.1–3 can function as AMPs.

Sign in / Sign up

Export Citation Format

Share Document