Showing papers on "Antibacterial activity published in 2012"
TL;DR: Reasonable bactericidal activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was demonstrated and the standard dilution micromethod determining the minimum inhibitory concentration leading to inhibition of bacterial growth was still under way.
714 citations
TL;DR: The antibacterial activity of CuO nanoparticles was found to be size-dependent and the highly stable minimum-sized monodispersed copper oxide nanoparticles synthesized during this study demonstrated a significant increase in antibacterial activities against both Gram-positive and -negative bacterial strains.
Abstract: Background
CuO is one of the most important transition metal oxides due to its captivating properties. It is used in various technological applications such as high critical temperature superconductors, gas sensors, in photoconductive applications, and so on. Recently, it has been used as an antimicrobial agent against various bacterial species. Here we synthesized different sized CuO nanoparticles and explored the size-dependent antibacterial activity of each CuO nanoparticles preparation.
620 citations
TL;DR: It is confirmed that the antibacterial effect of bare as well as TG capped ZnO NPs were due to membrane lipid peroxidation caused by the ROS generated during Zn O NPs interaction in culture medium.
371 citations
TL;DR: In this paper, the antimicrobial activity of ZnO nanoparticles against gram-negative and gram-positive bacteria was determined using bacteriological tests such as disc and well diffusion agar methods, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC).
Abstract: The aim of the present study is to determine the antimicrobial activity of ZnO nanoparticles against Gram-negative and Gram-positive bacteria Escherichia coli (E coli) and Staphylococcus aureus (S aureus) were used as test microorganisms The effects of particle size and concentration on the antibacterial activity of ZnO nanoparticles was studied using bacteriological tests such as disc and well diffusion agar methods, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) These tests were performed in nutrient broth and nutrient agar following standard methods In addition, the effect of different concentrations of ZnO nanoparticles on the growth of E coli and S aureus was measured with respect of time The minimum inhibitory concentration was determined using seven different concentrations of ZnO nanoparticles including 16, 8, 4, 2, 1 and 05 mg/ml The MIC value for E coli and S aureus was 1 and 05 mg/ml, respectively The results showed that ZnO nanoparticles have antibacterial inhibition zone of 29 and 19 mm at the concentration of 10 mg/ml against E coli and S aureus, respectively Gram-negative bacteria seemed to be more resistant to ZnO nanoparticles than Gram-positive bacteria It was found that the antibacterial activity of ZnO nanoparticles increased with decreasing particle size and increasing powder concentration The antibacterial effect of ZnO nanoparticles was time dependent and takes effect gradually ZnO bulk powder showed no significant antibacterial activity
Key word: ZnO nanoparticle, Escherichia coli, Staphylococcus aureus, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC)
362 citations
TL;DR: The activity of the individual compounds, their contribution to the complex antibacterial activity of honey, a novel approach to identify additional honey antibacterial compounds, and the implications of the novel developments for standardization of honey for medical applications are discussed.
Abstract: The antibacterial activity of honey has been known since the 19th century. Recently, the potent activity of honey against antibiotic-resistant bacteria has further increased the interest for application of honey, but incomplete knowledge of the antibacterial activity is a major obstacle for clinical applicability. The high sugar concentration, hydrogen peroxide, and the low pH are well-known antibacterial factors in honey and more recently, methylglyoxal and the antimicrobial peptide bee defensin-1 were identified as important antibacterial compounds in honey. The antibacterial activity of honey is highly complex due to the involvement of multiple compounds and due to the large variation in the concentrations of these compounds among honeys. The current review will elaborate on the antibacterial compounds in honey. We discuss the activity of the individual compounds, their contribution to the complex antibacterial activity of honey, a novel approach to identify additional honey antibacterial compounds, and the implications of the novel developments for standardization of honey for medical applications.
335 citations
TL;DR: Evaluated the antibacterial activity of starch-stabilized AgNPs against a panel of human pathogens commonly associated with air, water and food borne infections and suggested Ag NPs as a promising template for the design of novel antibacterial agents.
301 citations
TL;DR: In this paper, a polyethersulfone (PES) hollow fiber membrane was used to obtain both organic antifouling and antibacterial properties, and the silver nanoparticles were detected by X-ray photoelectron spectroscopy and transmission electron microscopy.
258 citations
TL;DR: The results indicated that 5 mg/L AgNPs inhibited ~50% of the growth of 106 colony forming units per milliliter (cfu/mL) E. coli cells in liquid Luria–Bertani (LB) medium, and dose-dependent antimicrobial activity was higher at increased temperature (37°C) but was lower when the AgNPS were treated with acid at pH 2 before exposure to the bacteria.
Abstract: In this study, the conditions and mechanism of antibacterial activity of hydrophilic polymer coated silver nanoparticles (AgNPs) against E. coli O157:H7 (CMCC44828) as model pathogen was studied. The AgNPs were coated with amphiphilic polymer that introduced carboxyl groups on the surface to make it water-soluble. The AgNPs were exposed to various treatment conditions of pH and temperature before these were combined with the E. coli. The mechanism of the antibacterial activity was studied through the formation of reactive oxygen species (ROS) that was later suppressed with antioxidant to establish correlation with the AgNPs antimicrobial activity. Studies were carried out at both anaerobic and aerobic conditions. The results indicated that 5 mg/L AgNPs inhibited ~50% of the growth of 106 colony forming units per milliliter (cfu/mL) E. coli cells in liquid Luria–Bertani (LB) medium. This dose-dependent antimicrobial activity was higher at increased temperature (37°C) but was lower when the AgNPs were treated with acid at pH 2 before exposure to the bacteria. It was also established that the conditions of higher antimicrobial effect generated more ROS that was dependent on the presence of oxygen. The antibacterial activity was suppressed in the presence of an antioxidant.
233 citations
TL;DR: Silver nanoparticles have potential as a combination therapeutic agent for the treatment of infectious diseases by bacteria and were found to have antibacterial effects and synergistic activities.
Abstract: Silver nanoparticles (nano-Ags), which have well-known antimicrobial properties, are used extensively in various medical and general applications. In this study, the combination effects between nano-Ags and the conventional antibiotics ampicillin, chloramphenicol and kanamycin against various pathogenic bacteria were investigated. The MIC and fractional inhibitory concentration index (FICI) were determined to confirm antibacterial susceptibility and synergistic effects. The results showed that nano-Ags possessed antibacterial effects and synergistic activities. The antibiofilm activities of nano-Ags alone or in combination with antibiotics were also investigated. Formation of biofilm is associated with resistance to antimicrobial agents and chronic bacterial infections. The results indicated that nano-Ags also had antibiofilm activities. To understand these effects of nano-Ags, an ATPase inhibitor assay, permeability assay and hydroxyl radical assay were conducted. The antibacterial activity of nano-Ags was influenced by ATP-associated metabolism rather than by the permeability of the outer membrane. Additionally, nano-Ags generated hydroxyl radicals, a highly reactive oxygen species induced by bactericidal agents. It was concluded that nano-Ags have potential as a combination therapeutic agent for the treatment of infectious diseases by bacteria.
220 citations
TL;DR: It is demonstrated that sulfone derivatives containing 1,3,4-oxadiazole can be used to develop potential bactericides for plants and the control effect of compound 5'j against tobacco bacterial wilt was better than that of the commercial bactericide Saisentong.
Abstract: A series of new sulfone compounds containing the 1,3,4-oxadiazole moiety were designed and synthesized. Their structures were identified by 1H and 13C nuclear magnetic resonance and elemental analyses. Antibacterial bioassays indicated that most compounds exhibited promising in vitro antibacterial bioactivities against tobacco bacterial wilt at 200 μg/mL. The relationship between structure and antibacterial activity was also discussed. Among the title compounds, 5′c, 5′h, 5′i, and 5′j could inhibit mycelia growth of Ralstonia solanacearum in vitro by approximately 50% (EC50) at 39.8, 60.3, 47.9, and 32.1 μg/mL, respectively. Among them, compound 5′j was identified as the most promising candidate due to its stronger effect than that of Kocide 3000 [Cu(OH)2] within the same concentration range. Field trials demonstrated that the control effect of compound 5′j against tobacco bacterial wilt was better than that of the commercial bactericide Saisentong. For the first time, the present work demonstrated that s...
219 citations
TL;DR: In this study, Rosmarinus officinalis L. essential oil showed greater activity than its components in both antibacterial and anticancer test systems, and the activities were mostly related to their concentrations.
Abstract: In this study, Rosmarinus officinalis L. essential oil and three of its main components 1,8-cineole (27.23%), α-pinene (19.43%) and β-pinene (6.71%) were evaluated for their in vitro antibacterial activities and toxicology properties. R. officinalis L. essential oil possessed similar antibacterial activities to α-pinene, and a little bit better than β-pinene, while 1,8-cineole possessed the lowest antibacterial activities. R. officinalis L. essential oil exhibited the strongest cytotoxicity towards three human cancer cells. Its inhibition concentration 50% (IC50) values on SK-OV-3, HO-8910 and Bel-7402 were 0.025‰, 0.076‰ and 0.13‰ (v/v), respectively. The cytotoxicity of all the test samples on SK-OV-3 was significantly stronger than on HO-8910 and Bel-7402. In general, R. officinalis L. essential oil showed greater activity than its components in both antibacterial and anticancer test systems, and the activities were mostly related to their concentrations.
TL;DR: An antibacterial effect of Cu-NPs was observed in Gram-positive Bacillus subtilis and Staphylococcus aureus, for which the values of minimum inhibitory concentration and minimum bactericidal concentration were close to that for E. coli.
Abstract: A method for preparation of copper nanoparticles (Cu-NPs) was developed by simple reduction of CuCl2 in the presence of gelatin as a stabilizer and without applying stringent conditions like purging with nitrogen. The NPs were characterized by spectrophotometry, dynamic light scattering, x-ray diffraction, transmission electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy. The particles were about 50-60 nm in size and highly stable. The antibacterial activity of this Cu-NP on Gram-negative Escherichia coli was demonstrated by the methods of agar plating, flow cytometry and phase contrast microscopy. The minimum inhibitory concentration (3.0 µg ml(-1)), minimum bactericidal concentration (7.5 µg ml(-1)) and susceptibility constant (0.92) showed that this Cu-NP is highly effective against E. coli at a much lower concentration than that reported previously. Treatment with Cu-NPs made E. coli cells filamentous. The higher the concentration of Cu-NPs, the greater the population of filamentous cells; average filament size varied from 7 to 20 µm compared to the normal cell size of ∼2.5 µm. Both filamentation and killing of cells by Cu-NPs (7.5 µg ml(-1)) also occurred in an E. coli strain resistant to multiple antibiotics. Moreover, an antibacterial effect of Cu-NPs was also observed in Gram-positive Bacillus subtilis and Staphylococcus aureus, for which the values of minimum inhibitory concentration and minimum bactericidal concentration were close to that for E. coli.
TL;DR: It was suggested that the mechanism of the antibacterial activity of the MgO NPs relied on the presence of defects or oxygen vacancy at the surface of the nanoparticle which led to the lipid peroxidation and reactive oxygen species generation.
Abstract: Antibacterial activity of MgO nanoparticles (NPs) was evaluated against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa as well as the Gram-positive bacterium Staphylococcus aureus by microtitre plate-based assay incorporating resazurin as an indicator of cell growth. MgO NPs exhibited antibacterial activity with minimal inhibitory concentration of 500 μg/mL against E. coli and 1,000 μg/mL for P. aeruginosa and S. aureus. MgO NPs enhanced ultrasound-induced lipid peroxidation in the liposomal membrane. It was suggested that the mechanism of the antibacterial activity of the MgO NPs relied on the presence of defects or oxygen vacancy at the surface of the nanoparticle which led to the lipid peroxidation and reactive oxygen species generation.
TL;DR: It is concluded that at a specific dose, chitosan-based AgNPs kill bacteria without harming the host cells, thus representing a potential template for the design of antibacterial agents to decrease bacterial colonization and to overcome the problem of drug resistance.
Abstract: Background: Pathogenic bacteria are able to develop various strategies to counteract the bactericidal action of antibiotics. Silver nanoparticles (AgNPs) have emerged as a potential alternative to conventional antibiotics because of their potent antimicrobial properties. The purpose of this study was to synthesize chitosan-stabilized AgNPs (CS-AgNPs) and test for their cytotoxic, genotoxic, macrophage cell uptake, antibacterial, and antibiofilm activities. Methods: AgNPs were synthesized using chitosan as both a stabilizing and a reducing agent. Antibacterial activity was determined by colony-forming unit assay and scanning electron microscopy. Genotoxic and cytotoxic activity were determined by DNA fragmentation, comet, and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays. Cellular uptake and intracellular antibacterial activity were tested on macrophages. Results: CS-AgNPs exhibited potent antibacterial activity against different human pathogens and also impeded bacterial biofilm formation. Scanning electron microscopy analysis indicated that CS-AgNPs kill bacteria by disrupting the cell membrane. CS-AgNPs showed no significant cytotoxic or DNA damage effect on macrophages at the bactericidal dose. Propidium iodide staining indicated active endocytosis of CS-AgNPs resulting in reduced intracellular bacterial survival in macrophages. Conclusion: The present study concludes that at a specific dose, chitosan-based AgNPs kill bacteria without harming the host cells, thus representing a potential template for the design of antibacterial agents to decrease bacterial colonization and to overcome the problem of drug
TL;DR: SAR studies show that arginine content largely influences the hydrogel's antibacterial activity, and influences their bulk rheological properties, and culminated in an optimized gel, composed of the peptide PEP6R (VKVRVRVRV(D)PPTRVRVRVKV).
TL;DR: Since MWCNTs have lower cytotoxicity than single-walled carbon nanotubes, their functionalization with cationic amino acids could be a beneficial approach in the disinfection industry.
TL;DR: The results suggest that the use of grape seed extract is a feasible alternative as antibacterial and antioxidant agents to prevent the deterioration of stored foods by bacteria and oxidation.
TL;DR: This study presents a highly efficient process for the synthesis of optically active pyranocoumarins and 2-amino-4H-chromenes through an organocatalytic Knoevenagel/Michael/cyclization sequence, and the preliminary biological studies of these new heterocyclic compounds revealed potent antibacterial activity.
Abstract: Function-oriented design and synthesis of chiral small molecules with novel activity is a key goal in modern organic chemistry. As multiple antibiotic-resistant pathogens are emerging and causing serious diseases, the need for practical routes for the development of new types of antibacterial agents is very urgent. Herein, we present a highly efficient process for the synthesis of optically active pyranocoumarins and 2-amino-4H-chromenes through an organocatalytic Knoevenagel/Michael/cyclization sequence, and the preliminary biological studies of these new heterocyclic compounds revealed potent antibacterial activity. This study provides a novel strategy for further research and development of new types of antibacterial agents effective against human pathogens.
TL;DR: How various classes of dendrimers have the potential to improve upon or replace certain antibiotics are described and how the unexplored areas in this field of research will be mentioned to present opportunities for additional studies regarding the use of dendedrimers as antimicrobial agents.
Abstract: The emergence and re-emergence of bacterial strains that are resistant to current antibiotics reveal the clinical need for new agents that possess broad-spectrum antibacterial activity. Furthermore, bacteriophobic coatings that repel bacteria are important for medical devices, as the lifetime, reliability, and performance of implant devices are hindered by bacterial adhesion and infection. Dendrimers, a specific class of monodisperse macromolecules, have recently shown potential to function as both antibacterial agents and antimicrobial surface coatings. This review discusses the limitations with currently used antibacterial agents and describes how various classes of dendrimers, including glycodendrimers, cationic dendrimers, anionic dendrimers, and peptide dendrimers, have the potential to improve upon or replace certain antibiotics. Furthermore, the unexplored areas in this field of research will be mentioned to present opportunities for additional studies regarding the use of dendrimers as antimicrobial agents.
TL;DR: The effect of surface modifications on antibacterial activity of ZnO under ambient illumination is investigated, and it is found that nanoparticles coated with different surface modifying reagents could exhibit higher or lower toxicity compared to bare ZNO, depending on the surface modifyingReagent used.
Abstract: In various practical applications, nanomaterials typically have functionalized surfaces. Yet, the studies of toxicity and antibacterial activity of functionalized nanoparticles are scarce. We investigated the effect of surface modifications on antibacterial activity of ZnO under ambient illumination, and we found that nanoparticles coated with different surface modifying reagents could exhibit higher or lower toxicity compared to bare ZnO, depending on the surface modifying reagent used. Different surface modifying reagent molecules resulted in differences in the release of Zn2+ ions and the production of reactive oxygen species (ROS). However, the antibacterial activity did not correlate with the ROS levels or the Zn2+ ion release. One of the surface-modified ZnO samples exhibited significantly lower Zn2+ ion release while at the same time exhibiting improved antibacterial activity. In all cases, damage of the cell wall membranes and/or changes in the membrane permeability have been observed, together with the changes in ATR-FTIR spectra indicating differences in protein conformation. Mechanisms of antibacterial activity are discussed.
TL;DR: In the current work chitosan was extracted from shrimp shells and then used as antibacterial exhaust finishing agent for grafted bamboo rayon and showed antibacterial activity against both types of bacterias which was durable till 30 washes.
TL;DR: In this paper, an environmentally benign and facile approach for production of silver nanoparticles (AgNPs) was proposed for the first time by hydrothermal synthesis using bacterial cellulose (BC) as both the reducing and stabilizing agent, without any chemical reagents introduced.
TL;DR: Results show that the 0.3 Ag coatings offer conditions for optimum cell growth next to antibacterial properties, which makes them extremely useful for the development of new antibacterial dental and orthopedic implants.
TL;DR: The use of microtitre plates enabled a variety of sol-gel coatings to be screened for their antibacterial activity against a wide range of bacteria in a relatively short time and the broad-spectrum antib bacterial activity of the silver doped Sol-gel showed its potential for use as a coating for biomaterials.
TL;DR: It is found that SNPSA exhibited strong antibacterial activity in vitro and ex vivo, and promoted MC3T3-E1 pre-osteoblasts proliferation and maturation in vitro, and induced osteogenesis while suppressing bacterial survival in contaminated rat femoral canals.
TL;DR: In this article, the use of nanostructured silver vanadate as a promising antibacterial additive to water-based paints that has potential for applications in bathrooms, kitchens, and hospital environments was reported.
TL;DR: The essential oil and its major components exhibited broad spectrum inhibition against all the bacterial strains with Gram-positive being more susceptible to the oil than Gram-negative bacteria.
TL;DR: The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii.
Abstract: Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg=0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a=b=9.435 A, c=6.876 A for xAg=0.05, a=b=9.443 A, c=6.875 A for xAg=0.2, and a=b=9.445 A, c=6.877 A for xAg=0.3 are in good agreement with the standard of a=b=9.418 A, c=6.884 A (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg=0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii).
01 Jan 2012
TL;DR: Results of antibacterial tests show that this hybrid nanomaterial has a promising antibacterial activity against several types of bacteria strains, such as methicillin-resistant Staphylococcus aureas, Enterococcus faecalis, Escherichia coli, and Salmonella enterica Typhimurium.
Abstract: Inthisarticle,wereporttheuseofnanostructuredsilvervanadateasapromisingantibacterialadditivetowater-basedpaintsthathaspotential for applications in bathrooms, kitchens, and hospital environments. This hybrid nanomaterial was prepared by a simple and fast precipitation reaction involving silver nitrate and ammonium vanadate, dismissing the hydrothermal treatment. The preparation involved using Ag vanadate nanowires(β-AgVO3)withdiametersrangingfrom20to60nmanddecoratedwithsilver(Ag)nanoparticles(NPs)withdiametersrangingfrom 5 to 40 nm. Results of antibacterial tests show that this hybrid material has a promising antibacterial activity against several types of bacteria strains, such as methicillin-resistant Staphylococcus aureas (MRSA), Enterococcus faecalis, Escherichia coli, and Salmonella enterica Typhimurium. The evaluated material exhibits antibacterial activity 30 times larger than that of Oxacillin. In addition, this nanomaterial was tested as an antibacterial additive to water-based paints, and formulations with 1% show a 4-mm inhibition zone against a MRSA strain. From the Clinical Editor: In this study, silver nanoparticles are studied as additives to water based paints to provide antibacterial properties. With the rise of multi-resistant organisms, the methods outlined in this work may enable the establishment of improved sanitary conditions for health care workers and beyond.
DOI•
05 Jun 2012
TL;DR: The results suggest that the extracts of boldo, hops, licorice and yerba mansa could be considered as potentially effective antibacterial agents against Gram-positive bacteria including MRSA.
Abstract: Medicinal plant extracts prepared with selected ethanol concentrations from eight species, Peumus boldus (boldo leaf), Agathosma betulina (buchu leaf), Echinacea angustifolia (echinacea root), Humulus lupulus (hops strobile), Glycyrrhiza glabra (licorice root), Mahonia aquifolium (Oregon grape root), Usnea barbata (usnea lichen), and Anemopsis californica (yerba mansa root), were screened for antibacterial activity against four Gram-positive and four Gram-negative pathogens. The antibacterial activity of the extracts (50, 70, and 90% ethanol) was evaluated using a standard well assay and microbroth dilution method. Minimum bactericidal concentrations (MBCs) were also determined for each extract. Plant extracts showed strong antibacterial action against Gram-positive bacteria, Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Streptococcus pyogenes, while negligible to no inhibitory activity against Gram-negative bacteria; Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enteritidis was observed. Among the plant extracts, the boldo, hops, licorice and yerba mansa exhibited a strong antibacterial action at all three ethanol concentrations. Of these four, hops showed the strongest activity at 90% ethanol. Echinacea angustifolia extracts did not show any considerable antibacterial activity, while usnea showed strong activity only at 90% against S. epidermis. Except Echinacea angustifolia and usnea, the plant extracts were strongly inhibitory towards the MRSA strain. Buchu, yerba mansa and Oregon grape showed higher activity at 50% or 70% on MRSA. MBCs varied from 1/4 to >1/256 dilution levels and were in agreement with well assay results. The results suggest that the extracts of boldo, hops, licorice and yerba mansa could be considered as potentially effective antibacterial agents against Gram-positive bacteria including MRSA. For hops, buchu, Oregon grape and usnea, the activity is dependent on the concentration of ethanol used in the extraction procedure. The ratio of ethanol/water mixture used for extraction of medicinal plants is an important factor to obtain optimum antibacterial activity.