scholarly journals Antimicrobial activity and mode of action of 1,8-cineol against carbapenemase-producing Klebsiella pneumoniae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chew-Li Moo ◽  
Mohd Azuraidi Osman ◽  
Shun-Kai Yang ◽  
Wai-Sum Yap ◽  
Saila Ismail ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antimicrobial Activity ◽  
Cell Membrane ◽  
Klebsiella Pneumoniae ◽  
Ethidium Bromide ◽  
Bacterial Cell ◽  
Mode Of Action ◽  
Membrane Damage ◽  
Electron Microscopies ◽  
Bacterial Cell Membrane

AbstractAntimicrobial resistance remains one of the most challenging issues that threatens the health of people around the world. Plant-derived natural compounds have received considerable attention for their potential role to mitigate antibiotic resistance. This study was carried out to assess the antimicrobial activity and mode of action of a monoterpene, 1,8-cineol (CN) against carbapenemase-producing Klebsiella pneumoniae (KPC-KP). Results showed that resazurin microplate assay and time-kill analysis revealed bactericidal effects of CN at 28.83 mg/mL. Zeta potential showed that CN increased the surface charge of bacteria and an increase of outer membrane permeability was also detected. CN was able to cause leakage of proteins and nucleic acids in KPC-KP cells upon exposure to CN and ethidium bromide influx/efflux experiment showed the uptake of ethidium bromide into the cell; this was attributed to membrane damage. CN was also found to induce oxidative stress in CN-treated KPC-KP cells through generation of reactive oxygen species which initiated lipid peroxidation and thus damaging the bacterial cell membrane. Scanning and transmission electron microscopies further confirmed the disruption of bacterial cell membrane and loss of intracellular materials. In this study, we demonstrated that CN induced oxidative stress and membrane damage resulting in KPC-KP cell death.

scholarly journals Combinatorial Antimicrobial Efficacy and Mechanism of Linalool Against Clinically Relevant Klebsiella pneumoniae

2021 ◽  
Vol 12 ◽  
Author(s):  
Shun-Kai Yang ◽  
Khatijah Yusoff ◽  
Mokrish Ajat ◽  
Chien-Yeong Wee ◽  
Polly-Soo-Xi Yap ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Membrane Damage ◽  
Bacterial Membrane ◽  
Bacterial Cells ◽  
Bacterial Killing ◽  
Potential Measurement ◽  
Bacterial Surface ◽  
Electron Microscopies

Antibiotic–adjuvant combinatory therapy serves as a viable treatment option in addressing antibiotic resistance in the clinical setting. This study was carried out to assess and characterize the adjuvant potential and mode of action of linalool against carbapenemase-producing Klebsiella pneumoniae (KPC-KP). Linalool exhibited bactericidal activity alone (11,250 μg/ml) and in combination with meropenem (5,625 μg/ml). Comparative proteomic analysis showed significant reduction in the number of cytoplasmic and membrane proteins, indicating membrane damage in linalool-treated KPC-KP cells. Upregulation of oxidative stress regulator proteins and downregulation of oxidative stress-sensitive proteins indicated oxidative stress. Zeta potential measurement and outer membrane permeability assay revealed that linalool increases the bacterial surface charge as well as the membrane permeability. Intracellular leakage of nucleic acid and proteins was detected upon linalool treatment. Scanning and transmission electron microscopies further revealed the breakage of bacterial membrane and loss of intracellular materials. Linalool induced oxidative stress by generating reactive oxygen species (ROS) which initiates lipid peroxidation, leading to damage of the bacterial membrane. This leads to intracellular leakage, eventually killing the KPC-KP cells. Our study demonstrated that linalool possesses great potential in future clinical applications as an adjuvant along with existing antibiotics attributed to their ability in disrupting the bacterial membrane by inducing oxidative stress. This facilitates the uptake of antibiotics into the bacterial cells, enhancing bacterial killing.

scholarly journals Effect of Silver Nanoparticles on Blue Light Phototoxicity against Fusobacterium nucleatum

Biophysica ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 405-412
Author(s):  
Uziel Jeffet ◽  
Shiri Livne ◽  
Arkadi Rahmanov ◽  
Nir Sterer
Keyword(s):  
Silver Nanoparticles ◽  
Cell Membrane ◽  
Blue Light ◽  
Bacterial Cell ◽  
Light Exposure ◽  
Membrane Damage ◽  
Fusobacterium Nucleatum ◽  
Oxygen Species ◽  
Cell Membrane Damage ◽  
Bacterial Cell Membrane

A previous study showed that sub-lethal exposure of blue light caused cell membrane damage in Fusobacterium nucleatum (Fn). The aim of the present study was to test the combined effect of blue light and silver nanoparticles against Fn. Bacterial suspensions were exposed to blue light (400–500 nm) with or without silver nanoparticles (10 nm). Exposed and non-exposed samples were studied for malodor production (Odor judge scores), VSC levels (Halimeter), reactive oxygen species (ROS) production (fluorimeter), and bacterial cell membrane damage (fluorescence microscopy). The results showed that combining blue light exposure and silver nanoparticles significantly reduced malodor and VSC production by Fn concomitant with increased ROS levels and bacterial cell membrane damage. These results suggest that silver nanoparticles may increase blue light phototoxicity against Fn.

scholarly journals Correlative ex situ and Liquid-Cell TEM Observation of Bacterial Cell Membrane Damage Induced by Rough Surface Topology

2020 ◽  
Vol Volume 15 ◽  
pp. 1929-1938 ◽  
Author(s):  
David Banner ◽  
Emre Firlar ◽  
Justas Jakubonis ◽  
Yusuf Baggia ◽  
Jodi Finlay ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Rough Surface ◽  
Bacterial Cell ◽  
Membrane Damage ◽  
Surface Topology ◽  
Ex Situ ◽  
Cell Membrane Damage ◽  
Liquid Cell ◽  
Bacterial Cell Membrane

Design of bio-molecular interfaces using liquid crystals demonstrating endotoxin interactions with bacterial cell wall components

RSC Advances ◽  
2015 ◽  
Vol 5 (81) ◽  
pp. 66476-66486 ◽  
Author(s):  
Dibyendu Das ◽  
Sumyra Sidiq ◽  
Santanu Kumar Pal
Keyword(s):  
Cell Wall ◽  
Liquid Crystals ◽  
Cell Membrane ◽  
Bacterial Cell ◽  
Bacterial Cell Wall ◽  
Cell Wall Components ◽  
Bacterial Cell Membrane ◽  
Membrane Components ◽  
Wall Components

Liquid crystals offer a promising approach to study and quantify the interactions between different bacterial cell membrane components with endotoxin at an aqueous interface.

scholarly journals Insights into the Mode of Action of Chitosan as an Antibacterial Compound

2008 ◽  
Vol 74 (12) ◽  
pp. 3764-3773 ◽  
Author(s):  
Dina Raafat ◽  
Kristine von Bargen ◽  
Albert Haas ◽  
Hans-Georg Sahl
Keyword(s):  
Antimicrobial Activity ◽  
Cell Wall ◽  
Cell Membrane ◽  
Mode Of Action ◽  
Membrane Lipids ◽  
Expression Profiles ◽  
Transcriptional Response ◽  
Response Analysis ◽  
Sequence Of Events ◽  
Wide Range

ABSTRACT Chitosan is a polysaccharide biopolymer that combines a unique set of versatile physicochemical and biological characteristics which allow for a wide range of applications. Although its antimicrobial activity is well documented, its mode of action has hitherto remained only vaguely defined. In this work we investigated the antimicrobial mode of action of chitosan using a combination of approaches, including in vitro assays, killing kinetics, cellular leakage measurements, membrane potential estimations, and electron microscopy, in addition to transcriptional response analysis. Chitosan, whose antimicrobial activity was influenced by several factors, exhibited a dose-dependent growth-inhibitory effect. A simultaneous permeabilization of the cell membrane to small cellular components, coupled to a significant membrane depolarization, was detected. A concomitant interference with cell wall biosynthesis was not observed. Chitosan treatment of Staphylococcus simulans 22 cells did not give rise to cell wall lysis; the cell membrane also remained intact. Analysis of transcriptional response data revealed that chitosan treatment leads to multiple changes in the expression profiles of Staphylococcus aureus SG511 genes involved in the regulation of stress and autolysis, as well as genes associated with energy metabolism. Finally, a possible mechanism for chitosan's activity is postulated. Although we contend that there might not be a single classical target that would explain chitosan's antimicrobial action, we speculate that binding of chitosan to teichoic acids, coupled with a potential extraction of membrane lipids (predominantly lipoteichoic acid) results in a sequence of events, ultimately leading to bacterial death.

scholarly journals Telavancin, a Multifunctional Lipoglycopeptide, Disrupts both Cell Wall Synthesis and Cell Membrane Integrity in Methicillin-Resistant Staphylococcus aureus

2005 ◽  
Vol 49 (3) ◽  
pp. 1127-1134 ◽  
Author(s):  
Deborah L. Higgins ◽  
Ray Chang ◽  
Dmitri V. Debabov ◽  
Joey Leung ◽  
Terry Wu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Bactericidal Activity ◽  
Bacterial Cell ◽  
Cell Membrane Potential ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Bacterial Cell Membrane

ABSTRACTThe emergence and spread of multidrug-resistant gram-positive bacteria represent a serious clinical problem. Telavancin is a novel lipoglycopeptide antibiotic that possesses rapid in vitro bactericidal activity against a broad spectrum of clinically relevant gram-positive pathogens. Here we demonstrate that telavancin's antibacterial activity derives from at least two mechanisms. As observed with vancomycin, telavancin inhibited late-stage peptidoglycan biosynthesis in a substrate-dependent fashion and bound the cell wall, as it did the lipid II surrogate tripeptideN,N′-diacetyl-l-lysinyl-d-alanyl-d-alanine, with high affinity. Telavancin also perturbed bacterial cell membrane potential and permeability. In methicillin-resistantStaphylococcus aureus, telavancin caused rapid, concentration-dependent depolarization of the plasma membrane, increases in permeability, and leakage of cellular ATP and K+. The timing of these changes correlated with rapid , concentration-dependent loss of bacterial viability, suggesting that the early bactericidal activity of telavancin results from dissipation of cell membrane potential and an increase in membrane permeability. Binding and cell fractionation studies provided direct evidence for an interaction of telavancin with the bacterial cell membrane; stronger binding interactions were observed with the bacterial cell wall and cell membrane relative to vancomycin. We suggest that this multifunctional mechanism of action confers advantageous antibacterial properties.

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