scholarly journals Broad-Spectrum Bactericidal Activity of a Synthetic Random Copolymer Based on 2-Methoxy-6-(4-Vinylbenzyloxy)-Benzylammonium Hydrochloride

2021 ◽  
Vol 22 (9) ◽  
pp. 5021
Author(s):  
Anna Maria Schito ◽  
Gabriela Piatti ◽  
Debora Caviglia ◽  
Guendalina Zuccari ◽  
Silvana Alfei
Keyword(s):  
Antibacterial Activity ◽  
Bactericidal Activity ◽  
Random Copolymer ◽  
Multidrug Resistant ◽  
Water Soluble ◽  
Ammonium Salts ◽  
Gram Negative ◽  
Minimal Inhibitory Concentrations ◽  
Bacterial Membranes ◽  
Different Strains

Low-molecular-weight organic ammonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Unfortunately, short-term functionality and high toxicity limit their clinical application. On the contrary, the equivalent macromolecular ammonium salts, derived from the polymerization of monomeric ammonium salts, have demonstrated improved antibacterial potency, a lower tendency to develop resistance, higher stability, long-term activity, and reduced toxicity. A water-soluble non-quaternary copolymeric ammonium salt (P7) was herein synthetized by copolymerizing 2-methoxy-6-(4-vinylbenzyloxy)-benzylammonium hydrochloride monomer with N, N-di-methyl-acrylamide. The antibacterial activity of P7 was assessed against several multidrug-resistant (MDR) clinical isolates of both Gram-positive and Gram-negative species. Except for colistin-resistant Pseudomonas aeruginosa, most isolates were susceptible to P7, also including some Gram-negative bacteria with a modified charge in the external membrane. P7 showed remarkable antibacterial activity against isolates of Enterococcus, Staphylococcus, Acinetobacter, and Pseudomonas, and on different strains of Escherichia coli and Stenotrophomonas maltophylia, regardless of their antibiotic resistance. The lowest minimal inhibitory concentrations (MICs) observed were 0.6–1.2 µM and the minimal bactericidal concentrations (MBC) were frequently overlapping with the MICs. In 24-h time–kill and turbidimetric studies, P7 displayed a rapid non-lytic bactericidal activity. P7 could therefore represent a novel and potent tool capable of counteracting infections sustained by several bacteria that are resistant to the presently available antibiotics.

scholarly journals Synthesis, Characterization and Bactericidal Activity of a 4-Ammoniumbuthylstyrene-Based Random Copolymer

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1140
Author(s):  
Silvana Alfei ◽  
Gabriella Piatti ◽  
Debora Caviglia ◽  
Anna Maria Schito
Keyword(s):  
Antibacterial Activity ◽  
Bactericidal Activity ◽  
Antimicrobial Agents ◽  
Water Solubility ◽  
Physicochemical Characterization ◽  
Random Copolymer ◽  
Water Soluble ◽  
Cationic Polymers ◽  
Severe Infections

The growing resistance of bacteria to current chemotherapy is a global concern that urgently requires new and effective antimicrobial agents, aimed at curing untreatable infection, reducing unacceptable healthcare costs and human mortality. Cationic polymers, that mimic antimicrobial cationic peptides, represent promising broad-spectrum agents, being less susceptible to develop resistance than low molecular weight antibiotics. We, thus, designed, and herein report, the synthesis and physicochemical characterization of a water-soluble cationic copolymer (P5), obtained by copolymerizing the laboratory-made monomer 4-ammoniumbuthylstyrene hydrochloride with di-methyl-acrylamide as uncharged diluent. The antibacterial activity of P5 was assessed against several multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species. Except for strains characterized by modifications of the membrane charge, most of the tested isolates were sensible to the new molecule. P5 showed remarkable antibacterial activity against several isolates of genera Enterococcus, Staphylococcus, Pseudomonas, Klebsiella, and against Escherichia coli, Acinetobacter baumannii and Stenotrophomonas maltophilia, displaying a minimum MIC value of 3.15 µM. In time-killing and turbidimetric studies, P5 displayed a rapid non-lytic bactericidal activity. Due to its water-solubility and wide bactericidal spectrum, P5 could represent a promising novel agent capable of overcoming severe infections sustained by bacteria resistant the presently available antibiotics.

scholarly journals The Zeamine Antibiotics Affect the Integrity of Bacterial Membranes

2014 ◽  
Vol 81 (3) ◽  
pp. 1139-1146 ◽  
Author(s):  
Joleen Masschelein ◽  
Charlien Clauwers ◽  
Karen Stalmans ◽  
Koen Nuyts ◽  
Wim De Borggraeve ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Electrostatic Interactions ◽  
Direct Consequence ◽  
Time Lapse ◽  
Multidrug Resistant ◽  
Peptide Antibiotics ◽  
Serratia Plymuthica ◽  
Gram Negative ◽  
Content Type ◽  
Bacterial Membranes

ABSTRACTThe zeamines (zeamine, zeamine I, and zeamine II) constitute an unusual class of cationic polyamine-polyketide-nonribosomal peptide antibiotics produced bySerratia plymuthicaRVH1. They exhibit potent bactericidal activity, killing a broad range of Gram-negative and Gram-positive bacteria, including multidrug-resistant pathogens. Examination of their specific mode of action and molecular target revealed that the zeamines affect the integrity of cell membranes. The zeamines provoke rapid release of carboxyfluorescein from unilamellar vesicles with different phospholipid compositions, demonstrating that they can interact directly with the lipid bilayer in the absence of a specific target. DNA, RNA, fatty acid, and protein biosynthetic processes ceased simultaneously at subinhibitory levels of the antibiotics, presumably as a direct consequence of membrane disruption. The zeamine antibiotics also facilitated the uptake of small molecules, such as 1-N-phenylnaphtylamine, indicating their ability to permeabilize the Gram-negative outer membrane (OM). The valine-linked polyketide moiety present in zeamine and zeamine I was found to increase the efficiency of this process. In contrast, translocation of the large hydrophilic fluorescent peptidoglycan binding protein PBDKZ-GFP was not facilitated, suggesting that the zeamines cause subtle perturbation of the OM rather than drastic alterations or defined pore formation. At zeamine concentrations above those required for growth inhibition, membrane lysis occurred as indicated by time-lapse microscopy. Together, these findings show that the bactericidal activity of the zeamines derives from generalized membrane permeabilization, which likely is initiated by electrostatic interactions with negatively charged membrane components.

scholarly journals Antibacterial Activity of a Cationic Antimicrobial Peptide against Multidrug-Resistant Gram-Negative Clinical Isolates and Their Potential Molecular Targets

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5035
Author(s):  
Sandra Patricia Rivera-Sánchez ◽  
Helen Astrid Agudelo-Góngora ◽  
José Oñate-Garzón ◽  
Liliana Janeth Flórez-Elvira ◽  
Adriana Correa ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Genomic Dna ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Bacterial Strains ◽  
Scanning Calorimetry ◽  
Cationic Antimicrobial Peptide ◽  
Gram Negative ◽  
Bacterial Membranes ◽  
Membrane Models

Antimicrobial resistance reduces the efficacy of antibiotics. Infections caused by multidrug-resistant (MDR), Gram-negative bacterial strains, such as Klebsiella pneumoniae (MDRKp) and Pseudomonas aeruginosa (MDRPa), are a serious threat to global health. However, cationic antimicrobial peptides (CAMPs) are promising as an alternative therapeutic strategy against MDR strains. In this study, the inhibitory activity of a cationic peptide, derived from cecropin D-like (ΔM2), against MDRKp and MDRPa clinical isolates, and its interaction with membrane models and bacterial genomic DNA were evaluated. In vitro antibacterial activity was determined using the broth microdilution test, whereas interactions with lipids and DNA were studied by differential scanning calorimetry and electronic absorption, respectively. A strong bactericidal effect of ΔM2 against MDR strains, with minimal inhibitory concentration (MIC) and minimal bactericidal concentrations (MBC) between 4 and 16 μg/mL, was observed. The peptide had a pronounced effect on the thermotropic behavior of the 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/1,2-dimyristoyl-sn-glycero-3-phosphorylglycerol (DMPG) membrane models that mimic bacterial membranes. Finally, the interaction between the peptide and genomic DNA (gDNA) showed a hyperchromic effect, which indicates that ΔM2 can denature bacterial DNA strands via the grooves.

scholarly journals In Vitro Antibacterial Activity of Propyl-Propane-Thiosulfinate and Propyl-Propane-Thiosulfonate Derived from Allium spp. against Gram-Negative and Gram-Positive Multidrug-Resistant Bacteria Isolated from Human Samples

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Antonio Sorlozano-Puerto ◽  
Maria Albertuz-Crespo ◽  
Isaac Lopez-Machado ◽  
Juan Jose Ariza-Romero ◽  
Alberto Baños-Arjona ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bactericidal Activity ◽  
Multidrug Resistant ◽  
Clinical Samples ◽  
Resistant Bacteria ◽  
Moderate Activity ◽  
Gram Positive ◽  
Gram Negative ◽  
Multiresistant Bacteria

Background. The aim of this study was to compare the in vitro antibacterial activity of two compounds derived from Alliaceae, PTS (propyl-propane-thiosulfinate), and PTSO (propyl-propane-thiosulfonate), with that of other antibiotics commonly used against bacteria isolated from humans. Materials and Methods. A total of 212 gram-negative bacilli and 267 gram-positive cocci isolated from human clinical samples and resistant to at least one group of antibiotics were selected. In order to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) to various antibiotics as well as PTS and PTSO, all isolates underwent broth microdilution assay. Results. PTS showed moderate activity against Enterobacteriaceae with MIC50 (and MBC50) and MIC90 (and MBC90) values of 256-512 mg/L, while PTSO showed greater activity with MIC50 and MIC90 values of 64-128 mg/L and MBC50 and MBC90 values of 128-512 mg/L. These data show the bactericidal activity of both compounds and indicate that PTSO was more active than PTS against this group of bacteria. Both compounds showed lower activity against P. aeruginosa (MIC50 = 1024 mg/L, MIC90 = 2048 mg/L, MBC50 = 2048 mg/L, and MBC90 = 2048 mg/L, for PTS; MIC50 = 512 mg/L, MIC90 = 1024 mg/L, MBC50 = 512 mg/L, and MBC90 = 2048 mg/L, for PTSO) compared to those obtained in others nonfermenting gram-negative bacilli (MIC50 = 128 mg/L, MIC90 = 512 mg/L, MBC50 = 128 mg/L, and MBC90 = 512 mg/L, for PTS; MIC50 = 64 mg/L, MIC90 = 256 mg/L, MBC50 = 64 mg/L, and MBC90 = 256 mg/L, for PTSO) and also indicate the bactericidal activity of both compounds against these groups of bacteria. Finally, the activity against S. aureus, E. faecalis, and S. agalactiae was higher than that observed against enterobacteria, especially in the case of PTSO (MIC50 = 8 mg/L, MIC90 = 8 mg/L, MBC50 = 32 mg/L, and MBC90 = 64 mg/L, in S. aureus; MIC50 = 4 mg/L, MIC90 = 8 mg/L, MBC50 = 8 mg/L, and MBC90 = 16 mg/L, in E. faecalis and S. agalactiae). Conclusion. PTS and PTSO have a significant broad spectrum antibacterial activity against multiresistant bacteria isolated from human clinical samples. Preliminary results in present work provide basic and useful information for development and potential use of these compounds in the treatment of human infections.

scholarly journals Facile fabrication of Tl4HgI6 nanostructures as a novel antibacterial and antibiofilm agents

2020 ◽  
Author(s):  
Maryam Karami ◽  
Mojgan Ghanbari ◽  
Omid Amiri ◽  
MASOUD SALAVATI-NIASARI ◽  
Somaye Rashki
Keyword(s):  
Raman Spectroscopy ◽  
Antibacterial Activity ◽  
Bactericidal Activity ◽  
Stoichiometric Ratio ◽  
Raman Spectrometry ◽  
Gram Negative ◽  
Biofilm Production ◽  
Facile Fabrication ◽  
Antibiofilm Agents ◽  
The Impact

Abstract In the present study, Tl4HgI6 nanostructures have been successfully fabricated through a simple precipitation route. The impact of TlI stoichiometric ratio to HgI2, and kind of surfactants was explored on purity, structure, and shape of samples. The as-fabricated Tl4HgI6 was characterized via XRD, EDX, FESEM, TEM, HRTEM, and Raman spectroscopy. Raman spectrometry corroborated the XRD outcomes, and revealed that the Tl4HgI6 nanoparticles were successfully fabricated. The structure, shape, and scale of the products were studied through FESEM images. It was observed that different factors have a notable aspect on the morphology and size of the products. The maximum antibacterial activity of Tl4HgI6 was perceived against S. aureus, E.coli and M. catarils. These outcomes demonstrate that Tl4HgI6 displays efficient bactericidal activity against Gram-positive and Gram-negative microorganisms. The anti-biofilm activity revealed that the best reduction of biofilm was recognized in higher Tl4HgI6 concentrations (2×MIC). Tl4HgI6 at 2×MIC concentration inhibits biofilm production by S. aureus and E. feacalis with an inhibition percentage of 95% and 90%, respectively.

scholarly journals Cyathea gigantea (Cyatheaceae) as an antimicrobial agent against multidrug resistant organisms

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Kathakali Nath ◽  
Anupam Das Talukdar ◽  
Mrinal Kanti Bhattacharya ◽  
Deepshikha Bhowmik ◽  
Shiela Chetri ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Antibacterial Property ◽  
Treatment Options ◽  
Multidrug Resistant ◽  
Diffusion Method ◽  
Synergistic Activity ◽  
Gram Positive ◽  
Traditional Use ◽  
Gram Negative ◽  
Multidrug Resistant Organisms

Abstract Background Rapid emergence of multidrug resistant (MDR) organisms in hospital and community settings often result into treatment failure, thus leading the clinicians with fewer treatment options. Cyathea gigantea, an ethnomedicinally important fern used in cuts and wound infections. So, if this medicinal plant is used in treating the MDR infections then it might bring certain relief in future treatment options. Methods Antibacterial activity of C. gigantea against MDR bacteria was assed using well diffusion and broth microdilution methods to determine the diameters of growth inhibition zones, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Synergistic activity was also determined with the conventional antibiotics by disc diffusion method followed by FIC index of each of the tested antibiotic was calculated. The active extract was then subjected to fractionation by column chromatography and antibacterial activity was done with each of the collected fractions. Results Crude extract of C. gigantea was found to be active against all the tested organisms. The MIC was 200 μg/ml against Gram-positive i.e., Staphylococcus aureus ATCC 25923 and 400 μg/ml against Gram-negative i.e., Escherichia coli ATCC 25922 and Pseudomonas aeruginosa PAO1, while the MBC was 400 μg/ml in case of Gram-positive and 800 μg/ml for Gram-negative. The synergistic activity revealed that the plant extract increased the antibacterial property of the studied antibiotics and the FIC index showed that significant synergistic activity was shown by ciprofloxacin followed by tetracycline, ampicillin and oxacillin. Antibacterial activity with the fractionated extract showed that the FR II, FR III and FR IV were active against both Gram-positive and Gram-negative bacteria, whereas FR I, FR V and FR VI did not show antibacterial property against any of the tested bacteria. Conclusions Extracts of C. gigantea was found active against both selected Gram-positive and Gram-negative organisms and thus offers the scientific basis for the traditional use of the fern. The present study also provides the basis for future study to validate the possible use against multidrug resistant organisms.

scholarly journals In Vitro Bactericidal Activity of Human β-Defensin 3 against Multidrug-Resistant Nosocomial Strains

2006 ◽  
Vol 50 (2) ◽  
pp. 806-809 ◽  
Author(s):  
Giuseppantonio Maisetta ◽  
Giovanna Batoni ◽  
Semih Esin ◽  
Walter Florio ◽  
Daria Bottai ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Bactericidal Activity ◽  
Stenotrophomonas Maltophilia ◽  
Bactericidal Effect ◽  
Multidrug Resistant ◽  
Bacterial Strains ◽  
Gram Negative

ABSTRACT The antimicrobial activity of human β-defensin 3 (hBD-3) against multidrug-resistant clinical isolates of Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii was evaluated. A fast bactericidal effect (within 20 min) against all bacterial strains tested was observed. The presence of 20% human serum abolished the bactericidal activity of hBD-3 against gram-negative strains and reduced the activity of the peptide against gram-positive strains.

scholarly journals Polymyxins and Bacterial Membranes: A Review of Antibacterial Activity and Mechanisms of Resistance

Membranes ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 181 ◽  
Author(s):  
Carole Ayoub Moubareck
Keyword(s):  
Current Knowledge ◽  
Acquired Resistance ◽  
Epidemiological Studies ◽  
Multidrug Resistant ◽  
Gram Negative ◽  
Bacterial Membranes ◽  
Antibiotic Development ◽  
Outer Membranes ◽  
Initial Discovery ◽  
Clinical Interest

Following their initial discovery in the 1940s, polymyxin antibiotics fell into disfavor due to their potential clinical toxicity, especially nephrotoxicity. However, the dry antibiotic development pipeline, together with the rising global prevalence of infections caused by multidrug-resistant (MDR) Gram-negative bacteria have both rejuvenated clinical interest in these polypeptide antibiotics. Parallel to the revival of their use, investigations into the mechanisms of action and resistance to polymyxins have intensified. With an initial known effect on biological membranes, research has uncovered the detailed molecular and chemical interactions that polymyxins have with Gram-negative outer membranes and lipopolysaccharide structure. In addition, genetic and epidemiological studies have revealed the basis of resistance to these agents. Nowadays, resistance to polymyxins in MDR Gram-negative pathogens is well elucidated, with chromosomal as well as plasmid-encoded, transferrable pathways. The aims of the current review are to highlight the important chemical, microbiological, and pharmacological properties of polymyxins, to discuss their mechanistic effects on bacterial membranes, and to revise the current knowledge about Gram-negative acquired resistance to these agents. Finally, recent research, directed towards new perspectives for improving these old agents utilized in the 21st century, to combat drug-resistant pathogens, is summarized.

scholarly journals CHLOROFORM FRACTION OF PARKIA JAVANICA BARK POSSESSES ANTIBACTERIAL ACTIVITY AGAINST MULTIDRUG RESISTANT GRAM NEGATIVE BACTERIA PREDOMINANTLY FOUND IN SKIN WOUND

2018 ◽  
Vol 8 (5) ◽  
pp. 184-189
Author(s):  
S Saha ◽  
P Karmakar ◽  
Samir Kumar Sil
Keyword(s):  
Antibacterial Activity ◽  
Cell Damage ◽  
Multidrug Resistant ◽  
Skin Wound ◽  
Lag Phase ◽  
Klebsiella Pneumonia ◽  
Chloroform Fraction ◽  
Bacterial Strains ◽  
Gram Negative ◽  
Antimicrobial Substances

Aim: To evaluate the antibacterial activity of Parkia javanica against gram negative MDR bacterial strains which are predominantly found in skin wound. Methods: The 5 different solvent fractions of Parkia javanica were screened for antibacterial activity against gram negative multi drug resistant bacterial strains namely Enterobacter aerugenes, Pseudomonas aeruginosa and Klebsiella pneumonia by serial dilution technique. Growth kinetics study was performed and percentage of ROS production was measured by NBT reduction assay. Results: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were obtained with a range of IC100 0.08-0.31 mg/ml in case of MDR bacterial strains. The lag phase of all extract treated bacteria is extended compared to untreated cells. The normalized % of ROS is increased in presence of Parkia javanica extract. Conclusions: This study suggests that, chloroform fraction of Parkia javanica possesses promising antimicrobial substances which are having activity against MDR bacterial strains and ROS induced bacterial cell damage could be the possible mediator of its antimicrobial activity. Keywords:   Parkia javanica, antibacterial activity, MDR bacterial strains, growth curve, ROS.

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