Hybrid Drug Delivery Patches Based on Spherical Cellulose Nanocrystals and Colloid Titania—Synthesis and Antibacterial Properties

PubMed Central

Svensson, Fredric G.; Agafonov, Alexander V.; Håkansson, Sebastian; Seisenbaeva, Gulaim A.

2018-01-01

Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H2SO4. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus. It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents. PMID:29642486

Hybrid Drug Delivery Patches Based on Spherical Cellulose Nanocrystals and Colloid Titania-Synthesis and Antibacterial Properties.

PubMed

Evdokimova, Olga L; Svensson, Fredric G; Agafonov, Alexander V; Håkansson, Sebastian; Seisenbaeva, Gulaim A; Kessler, Vadim G

2018-04-08

Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H₂SO₄. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus . It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents.

[Association between use of antibacterial agents in the first year of life and childhood asthma: a Meta analysis].

PubMed

Xie, Meng-Yao; Yuan, Yong-Hua; Liu, Li-Mei; Gu, Rong; Zhao, Xiao-Dong

2016-10-01

To evaluate the association between the use of antibacterial agents in the first years of life and childhood asthma. The Chinese and English databases CNKI, Wanfang Data, VIP, PubMed, and EBSCO were searched for prospective cohort studies on the association between the use of antibacterial agents in the first years of life and childhood asthma. Stata12.0 software was used to analyze the association through a Meta analysis. The articles with a high quality score and adjusted effective values for factors for lower respiratory tract infection were pooled, and a total of 8 studies were included. The results of the Meta analysis showed that the use of antibacterial agents in the first years of life increased the risk of childhood asthma (OR=1.14, 95%CI: 1.10-1.17, P<0.05). Compared with the children who used antibacterial agents 0-1 times in the first years of life, those who used more than 4 times had an increased risk of asthma (OR=1.28, 95%CI: 1.19-1.38, P<0.05). High-risk children (at least one immediate family member had asthma) who used antibacterial agents had an increased risk of asthma (OR=1.47, 95%CI: 1.20-1.81, P<0.05). The use of antibacterial agents in the first years of life increases the risk of childhood asthma. High-risk children who use antibacterial agents have an increased risk of asthma. The increased frequency of use of antibacterial agents in the first years of life is associated with an increased risk of childhood asthma, but the detailed dose relationship needs further investigation.

Effect of hydrogen peroxide on antibacterial activities of Canadian honeys.

PubMed

Brudzynski, Katrina

2006-12-01

Honey is recognized as an efficacious topical antimicrobial agent in the treatment of burns and wounds. The antimicrobial activity in some honeys depends on the endogenous hydrogen peroxide content. This study was aimed to determine whether honey's hydrogen peroxide level could serve as a honey-specific, activity-associated biomarker that would allow predicting and assessing the therapeutic effects of honey. Using a broth microdilution assay, I analyzed antibacterial activities of 42 Canadian honeys against two bacterial strains: Escherichia coli (ATCC 14948) and Bacillus subtilis (ATCC 6633). The MIC90 and MIC50 were established from the dose-response relationship between antibacterial activities and honey concentrations. The impact of H2O2 on antibacterial activity was determined (i) by measuring the levels of H2O2 before and after its removal by catalase and (ii) by correlating the results with levels of antibacterial activities. Canadian honeys demonstrated moderate to high antibacterial activity against both bacterial species. Both MIC90 and MIC50 revealed that the honeys exhibited a selective growth inhibitory activity against E. coli, and this activity was strongly influenced by endogenous H2O2 concentrations. Bacillus subtilis activity was marginally significantly correlated with H2O2 content. The removal of H2O2 by catalase reduced the honeys' antibacterial activity, but the enzyme was unable to completely decompose endogenous H2O2. The 25%-30% H2O2 "leftover" was significantly correlated with the honeys' residual antibacterial activity against E. coli. These data indicate that all Canadian honeys exhibited antibacterial activity, with higher selectivity against E. coli than B. subtilis, and that these antibacterial activities were correlated with hydrogen peroxide production in honeys. Hydrogen peroxide levels in honey, therefore, is a strong predictor of the honey's antibacterial activity.

Study of zwitterionic sulfopropylbetaine containing reactive siloxanes for application in antibacterial materials.

PubMed

Chen, Shiguo; Chen, Shaojun; Jiang, Song; Mo, Yangmiao; Luo, Junxuan; Tang, Jiaoning; Ge, Zaochuan

2011-07-01

Antibacterial agents receive a great deal of attention around the world due to the interesting academic problems of how to combat bacteria and of the beneficial health, social and economic effects of successful agents. Scientists are actively developing new antibacterial agents for biomaterial applications. This paper reports the novel antibacterial agent siloxane sulfopropylbetaine (SSPB), which contains reactive alkoxysilane groups. The structure and properties of SSPB were systematically investigated, with the results showing that SSPB contains both quaternary ammonium compounds and reactive siloxane groups. SSPB has good antibacterial activity against both Escherichia coli (E. coli, 8099) and Staphylococcus aureus (S. aureus, ATCC 6538). The minimal inhibition concentration is 70 μmol/ml SSPB against both E. coli and S. aureus. In addition, the SSPB antibacterial agent can be used in both weak acid and weak alkaline environments, functioning within the wide pH range of 4.0-9.0. The SSPB-modified glass surface killed 99.96% of both S. aureus and E. coli organisms within 24 h. No significant decrease was observed in this antibacterial activity after 20 washes. Moreover, SSPB does not induce a skin reaction and is nontoxic to animals. Thus, SSPB is an ideal candidate for future applications as a safe, environmentally friendly antibacterial agent. Copyright © 2011 Elsevier B.V. All rights reserved.

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment.

PubMed

Bílek, František; Křížová, Táňa; Lehocký, Marián

2011-11-01

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition zone on agar was used as in vitro test of antibacterial properties on two representative gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) strains. It was confirmed, that after grafting of polyallyamine, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity was observed by the sample containing triclosan. Samples covered by bronopol did not show significant antibacterial activity. Copyright © 2011 Elsevier B.V. All rights reserved.

In vitro toxicity testing for antibacterials against human keratinocytes.

PubMed

Smoot, E C; Kucan, J O; Roth, A; Mody, N; Debs, N

1991-05-01

The use of cultured human keratinocytes in an in vitro comparison of topical antibacterial toxicity for epithelial cells was examined. The complement of three assessments allows testing of epithelial migration, growth, and survival. The three assessments included (1) flow cytometry for determination of cell survival, (2) a comparison of confluent cell culture growth after antibacterial exposures, and (3) an evaluation of cell migration using a technique of dermal explants to study radial migration. A comparative ranking of the toxicities of the various topical antibacterials was determined with the three assessments. This has confirmed anecdotal reports that many of the topical antibacterials are cell-toxic and may inhibit wound healing. This information can be directly extrapolated to the clinical setting, unlike many of the animal data for wound healing that currently exist.

Shape-Dependent Skin Penetration of Silver Nanoparticles: Does It Really Matter?

PubMed Central

Tak, Yu Kyung; Pal, Sukdeb; Naoghare, Pravin K.; Rangasamy, Sabarinathan; Song, Joon Myong

2015-01-01

Advancements in nano-structured materials have facilitated several applications of nanoparticles (NPs). Skin penetration of NPs is a crucial factor for designing suitable topical antibacterial agents with low systemic toxicity. Available reports focus on size-dependent skin penetration of NPs, mainly through follicular pathways. Herein, for the first time, we demonstrate a proof-of-concept study that entails variations in skin permeability and diffusion coefficients, penetration rates and depth-of-penetration of differently shaped silver NPs (AgNPs) via intercellular pathways using both in vitro and in vivo models. The antimicrobial activity of AgNPs is known. Different shapes of AgNPs may exhibit diverse antimicrobial activities and skin penetration capabilities depending upon their active metallic facets. Consideration of the shape dependency of AgNPs in antimicrobial formulations could help developing an ideal topical agent with the highest efficacy and low systemic toxicity. PMID:26584777

Antibiotics and Resistance: Glossary

MedlinePlus

... R S T U V W X Y Z Antibacterials (see Antibacterial agents ) Antibiotics (see About bacteria and antibiotics ) Antibiotic ... antibiotic resistance? When and how to take antibiotics Antibacterial agents Bioterrorism & stockpiling antibiotics The Cost of Resistance ...

Antibacterial Resistance, Wayampis Amerindians, French Guyana

PubMed Central

Grenet, Karine; Guillemot, Didier; Jarlier, Vincent; Moreau, Brigitte; Dubourdieu, Stéphane; Ruimy, Raymond; Armand-Lefevre, Laurence; Bau, Pierre

2004-01-01

Drug resistance in fecal bacteria was high in Wayampis Amerindians who did not take antibacterial agents and were not hospitalized for 1 year. In the Wayampis Amerindians, an isolated traditional community in French Guyana, antibacterial use was 0.64 treatments per person per year. Hospitalization rate was 6.1% per year. Antibacterial drug–resistant bacteria can spread in persons who are not taking antibacterial agents. PMID:15207074

Nanosilver–Silica Composite: Prolonged Antibacterial Effects and Bacterial Interaction Mechanisms for Wound Dressings

PubMed Central

Ge, Yanling; Palva, Airi; Nordström, Katrina

2017-01-01

Infected superficial wounds were traditionally controlled by topical antibiotics until the emergence of antibiotic-resistant bacteria. Silver (Ag) is a kernel for alternative antibacterial agents to fight this resistance quandary. The present study demonstrates a method for immobilizing small-sized (~5 nm) silver nanoparticles on silica matrix to form a nanosilver–silica (Ag–SiO2) composite and shows the prolonged antibacterial effects of the composite in vitro. The composite exhibited a rapid initial Ag release after 24 h and a slower leaching after 48 and 72 h and was effective against both methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). Ultraviolet (UV)-irradiation was superior to filter-sterilization in retaining the antibacterial effects of the composite, through the higher remaining Ag concentration. A gauze, impregnated with the Ag–SiO2 composite, showed higher antibacterial effects against MRSA and E. coli than a commercial Ag-containing dressing, indicating a potential for the management and infection control of superficial wounds. Transmission and scanning transmission electron microscope analyses of the composite-treated MRSA revealed an interaction of the released silver ions with the bacterial cytoplasmic constituents, causing ultimately the loss of bacterial membranes. The present results indicate that the Ag–SiO2 composite, with prolonged antibacterial effects, is a promising candidate for wound dressing applications. PMID:28878170

Antibacterial property of fabrics coated by magnesium-based brucites

NASA Astrophysics Data System (ADS)

Wang, Ying; Sha, Lin; Zhao, Jiao; Li, Qian; Zhu, Yimin; Wang, Ninghui

2017-04-01

A kind of environmental-friendly magnesium-based antibacterial agent was reported for the first time, which was composited by brucites with different particle sizes. The antibacterial fabrics were produced by coating the magnesium-based antibacterial agents on the 260T polyester pongee fabrics with waterborne polyurethane. The coating process was simple, low-cost, and harmless to human health and environment. Characteristics of the antibacterial agents and fabrics were studied by particulate size distribution analyzer (PSDA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrated that the coating layer was covered tightly on the fabrics and compositing of different particles by a certain proportion made full filling of the coating layer. Meanwhile, compositing did not change the structure of brucites. The antibacterial fabrics presented strong antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with the reduction percentage of 96.6% and 100%, respectively, and the antibacterial fabrics attained excellent washing durability.

Role of Honey in Topical and Systemic Bacterial Infections.

PubMed

Hussain, Muhammad Barkaat

2018-01-01

The development of bacterial resistance to antibiotics has made it more difficult and expensive to treat infections. Honey is getting worldwide attention as a topical therapeutic agent for wound infections and potential future candidate for systemic infections. The purpose of this review was to summarise different antibacterial bio-active compounds in honey, their synergistic interaction and their clinical implications in topical and systemic infections. In addition, contemporary testing methods for evaluating peroxide and non-peroxide antibacterial activity of honey were also critically appraised. MEDLINE, EMBASE, Cochrane Library, Pub Med, reference lists and databases were used to review the literature. Honey contains several unique antibacterial components. These components are believed to act on diverse bacterial targets, are broad spectrum, operate synergistically, prevent biofilm formation, and decrease production of virulence factors. Moreover, honey has the ability to block bacterial communication (quorum sensing), and therefore, it is unlikely that bacteria develop resistance against honey. Bacterial resistance against honey has not been documented so far. Unlike conventional antibiotics, honey only targets pathogenic bacteria without disturbing the growth of normal gastrointestinal flora when taken orally. It also contains prebiotics, probiotics, and zinc and enhances the growth of beneficial gut flora. The presence of such plethora of antibacterial properties in one product makes it a promising candidate not only in wound infections but also in systemic and particularly for gastrointestinal infections. Agar diffusion assay, being used for evaluating antibacterial activity of honey, is not the most appropriate and sensitive assay as it only detects non-peroxide activity when present at a higher level. Therefore, there is a need to develop more sensitive techniques that may be capable of detecting and evaluating different important components in honey as well as their synergistic interaction. Keeping in view the current guidelines for treatment of diarrhea, honey is considered one of the potential candidates for treatment of diarrhea because it contains a natural combination of probiotics, prebiotics, and zinc. Therefore, it would be worthwhile if such a combination is tested in RCTs for treatment of diarrhea.

Topical application of zinc oxide nanoparticles reduces bacterial skin infection in mice and exhibits antibacterial activity by inducing oxidative stress response and cell membrane disintegration in macrophages.

PubMed

Pati, Rashmirekha; Mehta, Ranjit Kumar; Mohanty, Soumitra; Padhi, Avinash; Sengupta, Mitali; Vaseeharan, Baskarlingam; Goswami, Chandan; Sonawane, Avinash

2014-08-01

Here we studied immunological and antibacterial mechanisms of zinc oxide nanoparticles (ZnO-NPs) against human pathogens. ZnO-NPs showed more activity against Staphylococcus aureus and least against Mycobacterium bovis-BCG. However, BCG killing was significantly increased in synergy with antituberculous-drug rifampicin. Antibacterial mechanistic studies showed that ZnO-NPs disrupt bacterial cell membrane integrity, reduce cell surface hydrophobicity and down-regulate the transcription of oxidative stress-resistance genes in bacteria. ZnO-NP treatment also augmented the intracellular bacterial killing by inducing reactive oxygen species production and co-localization with Mycobacterium smegmatis-GFP in macrophages. Moreover, ZnO-NPs disrupted biofilm formation and inhibited hemolysis by hemolysin toxin producing S. aureus. Intradermal administration of ZnO-NPs significantly reduced the skin infection, bacterial load and inflammation in mice, and also improved infected skin architecture. We envision that this study offers novel insights into antimicrobial actions of ZnO-NPs and also demonstrates ZnO-NPs as a novel class of topical anti-infective agent for the treatment of skin infections. This in-depth study demonstrates properties of ZnO nanoparticles in infection prevention and treatment in several skin infection models, dissecting the potential mechanisms of action of these nanoparticles and paving the way to human applications. Copyright © 2014 Elsevier Inc. All rights reserved.

Potential Use of Essential Oil Isolated from Cleistocalyx operculatus Leaves as a Topical Dermatological Agent for Treatment of Burn Wound

PubMed Central

Le, Nghia-Thu Tram; Dam, Sao-Mai

2018-01-01

Several herbal remedies have been used as topical agents to cure burn wound, one of the most common injuries in worldwide. In this study, we investigated the potential use of Cleistocalyx operculatus essential oil to treat the burn wound. We identified a total of 13 bioactive compounds of essential oil, several of which exhibited the anti-inflammatory and antimicrobial activities. Furthermore, the essential oil showed the antibacterial effect against S. aureus but not with P. aeruginosa. The supportive effect of essential oil on burn wound healing process also has been proven. Among three groups of mice, wound contraction rate of essential oil treated group (100%) was significantly higher than tamanu oil treated (79%) and control mice (71%) after 20 days (0.22 ± 0.03 versus 0.31 ± 0.02 cm2, resp., p < 0.05). Histological studies revealed that burn wounds treated with essential oil formed a complete epidermal structure, thick and neatly arranged fibers, and scattered immune cells in burn wound. On the contrary, saline treated burn wound formed uneven epidermal layer with necrotic ulcer, infiltration of immune cells, and existence of granulation tissue. This finding demonstrated Cleistocalyx operculatus essential oil as promising topical dermatological agent to treat burn wound. PMID:29692805

Potential Use of Essential Oil Isolated from Cleistocalyx operculatus Leaves as a Topical Dermatological Agent for Treatment of Burn Wound.

PubMed

Tran, Gia-Buu; Le, Nghia-Thu Tram; Dam, Sao-Mai

2018-01-01

Several herbal remedies have been used as topical agents to cure burn wound, one of the most common injuries in worldwide. In this study, we investigated the potential use of Cleistocalyx operculatus essential oil to treat the burn wound. We identified a total of 13 bioactive compounds of essential oil, several of which exhibited the anti-inflammatory and antimicrobial activities. Furthermore, the essential oil showed the antibacterial effect against S. aureus but not with P. aeruginosa. The supportive effect of essential oil on burn wound healing process also has been proven. Among three groups of mice, wound contraction rate of essential oil treated group (100%) was significantly higher than tamanu oil treated (79%) and control mice (71%) after 20 days (0.22 ± 0.03 versus 0.31 ± 0.02 cm 2 , resp., p < 0.05). Histological studies revealed that burn wounds treated with essential oil formed a complete epidermal structure, thick and neatly arranged fibers, and scattered immune cells in burn wound. On the contrary, saline treated burn wound formed uneven epidermal layer with necrotic ulcer, infiltration of immune cells, and existence of granulation tissue. This finding demonstrated Cleistocalyx operculatus essential oil as promising topical dermatological agent to treat burn wound.

One-step synthesis and characterization of polyaniline nanofiber/silver nanoparticle composite networks as antibacterial agents.

PubMed

Poyraz, Selcuk; Cerkez, Idris; Huang, Tung Shi; Liu, Zhen; Kang, Litao; Luo, Jujie; Zhang, Xinyu

2014-11-26

Through a facile and effective seeding polymerization reaction via a one-step redox/complexation process, which took place in aqueous medium at ambient temperature, silver nanoparticles (Ag NPs) embedded polyaniline nanofiber (PANI NF) networks were synthesized as antibacterial agents. During the reaction, not only NF morphology formation of the resulting conducting polymers (CPs) but also amplification of the aqueous silver nitrate (AgNO3) solutions' oxidative potentials were managed by vanadium pentoxide (V2O5) sol-gel nanofibers, which acted as well-known nanofibrous seeding agents and the auxiliary oxidative agent at the same time. The PANI/Ag nanocomposites were proven to exhibit excellent antibacterial property against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Antibacterial property performance and average life span of the nanocomposite network were optimized through the homogeneous distribution/embedment of Ag NPs within one-dimensional (1-D) PANI NF matrix. The antibacterial efficacy tests and nanocomposite material characterization results further indicated that the sole components of PANI/Ag have a synergistic effect to each other in terms of antibacterial property. Thus, this well-known catalytic seeding approach via a one-step oxidative polymerization reaction can be considered as a general methodology and a substantial fabrication tool to synthesize Ag NP decorated nanofibrillar PANI networks as advanced antibacterial agents.

Investigation of the in vitro photocatalytic antibacterial activity of nanocrystalline TiO2 and coupled TiO2/Ag containing copolymer on the surface of medical grade titanium.

PubMed

Györgyey, Ágnes; Janovák, László; Ádám, András; Kopniczky, Judit; Tóth, Krisztián L; Deák, Ágota; Panayotov, Ivan; Cuisinier, Frédéric; Dékány, Imre; Turzó, Kinga

2016-07-01

Antibacterial surfaces have been in the focus of research for years, driven by an unmet clinical need to manage an increasing incidence of implant-associated infections. The use of silver has become a topic of interest because of its proven broad-spectrum antibacterial activity and track record as a coating agent of soft tissue implants and catheters. However, for the time being, the translation of these technological achievements for the improvement of the antibacterial property of hard tissue titanium (Ti) implants remains unsolved. In our study, we focused on the investigation of the photocatalysis mediated antibacterial activity of silver (Ag), and Ti nanoparticles instead of their pharmacological effects. We found that the photosensitisation of commercially pure titanium discs by coating them with an acrylate-based copolymer that embeds coupled Ag/Ti nanoparticles can initiate the photocatalytic decomposition of adsorbed S. salivarius after the irradiation with an ordinary visible light source. The clinical isolate of S. salivarius was characterised with MALDI-TOF mass spectrometer, while the multiplication of the bacteria on the surface of the discs was followed-up by MTT assay. Concerning practical relevance, the infected implant surfaces can be made accessible and irradiated by dental curing units with LED and plasma arc light sources, our research suggests that photocatalytic copolymer coating films may offer a promising solution for the improvement of the antibacterial properties of dental implants. © The Author(s) 2016.

Investigation of Mg(OH)2 nanoparticles as an antibacterial agent

NASA Astrophysics Data System (ADS)

Dong, Chunxu; Cairney, John; Sun, Qunhui; Maddan, Orville Lee; He, Gaohong; Deng, Yulin

2010-08-01

Our experimental results of using Mg(OH)2 nanoparticles as an antibacterial agent are reported in this study. The antibacterial behavior of Mg(OH)2 nanoparticles in liquid culture and in paper sheets was investigated. The colony forming units (CFU) counting and the headspace gas chromatography (HS-GC) measurement were used to determine the cell viability. Results indicate that Mg(OH)2 nanoparticles are effective antibacterial agent against Escherichia coli ( E. coli) and Burkholderia phytofirmans, and the OH- and Mg2+ ions in Mg(OH)2 water suspension were found not to be the reason for killing the bacteria. Mg(OH)2 nanoparticles could be added directly to wood pulp to make paper sheets, whose antibacterial efficiency increased with the increase of the nanoparticle amount. The possible mechanism of antibacterial effect of Mg(OH)2 nanoparticles is discussed.

Investigation of functional selenium nanoparticles as potent antimicrobial agents against superbugs.

PubMed

Huang, Xiaoquan; Chen, Xu; Chen, Qingchang; Yu, Qianqian; Sun, Dongdong; Liu, Jie

2016-01-01

Developing highly effective antibacterial agents is important for a wide range of applications. However, the emergence of multiple antibiotic-resistant bacteria poses a public health threat. Many developed agents have limited practical application due to chemical instability, low biocompatibility, and poor long-term antibacterial efficiency. In the following study, we synthesize a synergistic nanocomposite by conjugating quercetin (Qu) and acetylcholine (Ach) to the surface of Se nanoparticles (Qu-Ach@SeNPs). Quercetin has been reported to exhibit a wide range of biological activities related to their antibacterial activity and acetylcholine as a neurotransmitter, which can combine with the receptor on the bacterial cell. Arrows indicate NPs and arrowheads indicate compromised cell walls. The study demonstrated how Qu-Ach@SeNPs exhibit a synergistically enhanced antibacterial performance against the multidrug-resistant superbugs (MDRs) compared to Qu@SeNPs and Ach@SeNPs alone. Qu-Ach@SeNPs are effective against MDRs, such as Methicillin-resistant Staphylococcus aureus (MRSA), at a low dose. The mechanistic studies showed that Qu-Ach@SeNPs attach to the bacterial cell wall, causing irreversible damage to the membrane, and thereby achieving a remarkable synergistic antibacterial effect to inhibit MRSA. The findings suggested that the synergistic properties of quercetin and acetylcholine enhance the antibacterial activity of SeNPs. In this way, Qu-Ach@SeNPs comprise a new class of inorganic nano-antibacterial agents that can be used as useful applications in biomedical devices. The Qu-Ach@SeNPs have low cytotoxicity when tested on normal human cells in vitro. Qu-Ach@SeNPs are effective against MDRs, such as Methicillin-resistant S. aureus (MRSA), at a low dose. Importantly, Qu-Ach@SeNPs showed no emergence of resistance. These results suggest that Qu-Ach@SeNPs have excellent antibacterial activities. These agents can serve as good antibacterial agents against superbugs. Our data suggest that these antibacterial agents may have widespread application in the field of medicine for combating infectious diseases caused by MDRs, as well as other infectious diseases. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Preparation of active antibacterial LDPE surface through multistep physicochemical approach II: graft type effect on antibacterial properties.

PubMed

Bílek, František; Sulovská, Kateřina; Lehocký, Marián; Sáha, Petr; Humpolíček, Petr; Mozetič, Miran; Junkar, Ita

2013-02-01

Three monomers (allylamine, N-allylmethylamine and N,N-dimethylallylamine) were used for grafting onto air plasma activated LDPE surface. Antibacterial agent triclosan was anchored on such substrates. Influence of graft type on the antibacterial properties was determined. Increase of antibacterial activity and amount of deposited antibacterial agent for N-allylmethylamine and N,N-dimethylallylamine monomers were examined. Surface characteristics were measured by means of static contact angle measurement with surface energy evaluation, ATR-FTIR spectroscopy, XPS and SEM characterization analysis. Antibacterial properties were tested in vitro by inhibition zone method on agar plates for Staphylococcus aureus and Escherichia coli strains. Copyright © 2012 Elsevier B.V. All rights reserved.

Polyethyleneimine Capped Silver Nanoclusters as Efficient Antibacterial Agents.

PubMed

Xu, Dong; Wang, Qingyun; Yang, Tao; Cao, Jianzhong; Lin, Qinlu; Yuan, Zhiqin; Li, Le

2016-03-18

Development of efficient antibacterial agents is critical for human health. In the present study, we investigated the antibacterial activity of polyethyleneimine (PEI)-capped silver nanoclusters (PEI-AgNCs), based on the fact that nanoclusters normally have higher surface-to-volume ratios than traditional nanomaterials and PEI itself has a strong antimicrobial capacity. We synthesized stable silver nanoclusters by altering PEI molecular weight from 0.6 kDa to 25 kDa and characterized them by UV-Vis absorption and fluorescence spectroscopy and high resolution transmission electron microscopy. The sizes of AgNCs were around 2 nm in diameter and were little influenced by the molecular weight of PEIs. The antibacterial abilities of the four PEI-AgNCs were explored on agar plate and in liquid systems. Our results revealed that the antibacterial activity of PEI-AgNCs is excellent and the reduction of PEI molecular weight could result in the increased antibacterial capacity of PEI-AgNCs. Such proposed new materials might be useful as efficient antibacterial agents in practical clinical applications.

Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

NASA Astrophysics Data System (ADS)

Im, A.-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

2013-10-01

For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

Antibiotics in Serbian Households: a Source of Potential Health and Environmental Threats?

PubMed

Kusturica, Milica Paut; Tomić, Zdenko; Bukumirić, Zoran; Horvat, Olga; Pavlović, Nebojša; Mikov, Momir; Sabo, Ana

2015-06-01

Worldwide data indicate that antibiotics are frequently used inappropriately. The objective of this study was to investigate the extent of storage and wastage of antibacterial agents in households in Novi Sad, Serbia. The study was performed in 8 months period (December 2011-July 2012) in households in Novi Sad, Serbia. The households were randomly selected from the telephone directory. The interviewer performed the survey visiting each household. The total number of antibacterial agents in the 383 surveyed households was 318, constituting 7.3% of the total stored medications. From 383 families included in the study antibiotics were found in 178 (46.5%). In 13 (7.3%) families were found more than one pack of the same antibiotics. The median number of antibacterial agents per household was 1 (range 1-5). The most common antibacterial agents that were not in current use were cephalexin (22.1%) and amoxicillin (16.6%), followed by doxycycline (11.4%), sulfamethoxazole/trimethoprim (11.4%) and amoxicillin/clavulanic acid (9.2%). The percentage of expired antibacterial agents was 20.8%, while 85.2% were not currently in use. Antibacterial agents were commonly encountered in Serbian households, and a relatively large percentage was wasted. Informational and educational activities aimed at improving the public knowledge about antimicrobials play the leading role in reducing imprudent use of antibiotics. Copyright© by the National Institute of Public Health, Prague 2015.

Developing of a novel antibacterial agent by functionalization of graphene oxide with guanidine polymer with enhanced antibacterial activity

NASA Astrophysics Data System (ADS)

Li, Ping; Sun, Shiyu; Dong, Alideertu; Hao, Yanping; Shi, Shuangqiang; Sun, Zijia; Gao, Ge; Chen, Yuxin

2015-11-01

New materials with excellent antibacterial activity attract numerous research interests. Herein, a facile synthetic method of polyethylene glycol (PEG) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-PEG-PHGC), a novel antibacterial material, was reported. The as-prepared products were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray pattern (XRD) and elemental analysis. The antibacterial effect on the bacterial strain was investigated by incubating both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). The results show that GO-PEG-PHGC has enhanced antibacterial activity when compared to GO, GO-PEG or GO-PHGC alone. The improved antibacterial activity was described to be related to a better dispersion of GO-PEG-PHGC in the presence of PEG. This better dispersion leads to a greater contact between the bacteria membrane and nanomaterials, therefore leading to greater cell damage. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by this antibacterial agent. With the powerful antibacterial activity as well as its low cost and facile preparation, the GO-PEG-PHGC as a novel antibacterial agent can find potential application in the areas of healthcare and environmental engineering.

Discovery of an ultra-short linear antibacterial tetrapeptide with anti-MRSA activity from a structure-activity relationship study.

PubMed

Lau, Qiu Ying; Ng, Fui Mee; Cheong, Jin Wei Darryl; Yap, Yi Yong Alvin; Tan, Yoke Yan Fion; Jureen, Roland; Hill, Jeffrey; Chia, Cheng San Brian

2015-11-13

The overuse and misuse of antibiotics has resulted in the emergence of drug-resistant pathogenic bacteria, including meticillin-resistant Staphylococcus aureus (MRSA), the primary pathogen responsible for human skin and soft-tissue infections. Antibacterial peptides are known to kill bacteria by rapidly disrupting their membranes and are deemed plausible alternatives to conventional antibiotics. One advantage of their membrane-targeting mode of action is that bacteria are unlikely to develop resistance as changing their cell membrane structure and morphology would likely involve extensive genetic mutations. However, major concerns in using peptides as antibacterial drugs include their instability towards plasma proteases, toxicity towards human cells due to their membrane-targeting mode of action and high manufacturing cost. These concerns can be mitigated by developing peptides as topical agents, by the judicial selection of amino acids and developing very short peptides respectively. In this preliminary report, we reveal a linear, non-hemolytic tetrapeptide with rapid bactericidal activity against MRSA developed from a structure-activity relationship study based on the antimicrobial hexapeptide WRWRWR-NH2. Our finding opens promising avenues for the development of ultra-short antibacterials to treat multidrug-resistant MRSA skin and soft tissue infections. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Cellulosic/wool pigment prints with remarkable antibacterial functionalities.

PubMed

Ibrahim, N A; Eid, B M; Khalil, H M

2015-01-22

Several bio-active agents namely choline chloride, triclosan derivative, PEG-600 and 4-hydroxybenzophenone were successfully included into solvent-free pigment formulations, in a single-stage process, followed by screen printing and microwave-fixation to obtain antibacterial functionalized cellulosic/wool pigment prints. Results obtained signify that both the improvement in functionalization and coloration properties are governed by type of antibacterial agent, kind of substrate as well as pigment colorant. The imparted antibacterial activity of the loaded bio-active agents follows the decreasing order: G+ve (Staphylococcus aureus)>G-ve (Escherichia coli), keeping other parameters constant. The imparted functional and coloration properties showed no significant decrease even after 15 washings. Mode of interactions among the nominated substrates, the pigment paste constituents and the bioactive agents were also proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis and in vitro antibacterial activity of oxazolidine LBM-415 analogs as peptide deformylase inhibitors.

PubMed

Yu, Linliang; Zhou, Weicheng; Wang, Zhenyu

2011-03-01

The drug resistant bacteria pose a severe threat to human health. The increasing resistance of those pathogens to traditional antibacterial therapy renders the identification of new antibacterial agents with novel antibacterial mechanisms an urgent need. In this study, a series of (2S)-N-substituted-1-[(formyhydroxyamino)methyl]-1-oxohexyl]-2-oxazolidinecarboxamides were designed, synthesized and evaluated for in vitro antibacterial activity. Most of these compounds displayed good activities against Gram-positive organisms comparable to reference agent LBM-415. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

Synthesis of graphene oxide-quaternary ammonium nanocomposite with synergistic antibacterial activity to promote infected wound healing.

PubMed

Liu, Tengfei; Liu, Yuqing; Liu, Menglong; Wang, Ying; He, Weifeng; Shi, Gaoqiang; Hu, Xiaohong; Zhan, Rixing; Luo, Gaoxing; Xing, Malcolm; Wu, Jun

2018-01-01

Bacterial infection is one of the most common complications in burn, trauma, and chronic refractory wounds and is an impediment to healing. The frequent occurrence of antimicrobial-resistant bacteria due to irrational application of antibiotics increases treatment cost and mortality. Graphene oxide (GO) has been generally reported to possess high antimicrobial activity against a wide range of bacteria in vitro . In this study, a graphene oxide-quaternary ammonium salt (GO-QAS) nanocomposite was synthesized and thoroughly investigated for synergistic antibacterial activity, underlying antibacterial mechanisms and biocompatibility in vitro and in vivo . The GO-QAS nanocomposite was synthesized through amidation reactions of carboxylic group end-capped QAS polymers with primary amine-decorated GO to achieve high QAS loading ratios on nanosheets. Next, we investigated the antibacterial activity and biocompatibility of GO-QAS in vitro and in vivo . GO-QAS exhibited synergistic antibacterial activity against bacteria through not only mechanical membrane perturbation, including wrapping, bacterial membrane insertion, and bacterial membrane perforation, but also oxidative stress induction. In addition, it was found that GO-QAS could eradicate multidrug-resistant bacteria more effectively than conventional antibiotics. The in vitro and in vivo toxicity tests indicated that GO-QAS did not exhibit obvious toxicity towards mammalian cells or organs at low concentrations. Notably, GO-QAS topically applied on infected wounds maintained highly efficient antibacterial activity and promoted infected wound healing in vivo . The GO-QAS nanocomposite exhibits excellent synergistic antibacterial activity and good biocompatibility both in vitro and in vivo . The antibacterial mechanisms involve both mechanical membrane perturbation and oxidative stress induction. In addition, GO-QAS accelerated the healing process of infected wounds by promoting re-epithelialization and granulation tissue formation. Overall, the results indicated that the GO-QAS nanocomposite could be applied as a promising antimicrobial agent for infected wound management and antibacterial wound dressing synthesis.

Topical antibiotics and neurosurgery: Have we forgotten to study it?

PubMed Central

Alves, Raphael Vicente; Godoy, Roberto

2010-01-01

Background: For neurosurgery, the last decades have been a time of incredible improvement in areas such as imaging, microscopy, endoscopy, stereotactic guidance, navigation, radiosurgery and endovascular techniques. However, the efficacy of topical antibiotic prophylaxis in neurological operations remains to be established by neurosurgeons. Methods: The authors did an historical review of the literature regarding the utilization of topical antibiotic prophylaxis in neurological operations. The Pub Med database of the U.S. National Library of Medicine / National Institutes of Health was utilized as the primary source of the literature. The authors performed the search by using the following Mesh terms: “neurosurgery” or “neurosurgical procedures” and “administration, topical” and “antibiotic prophylaxis”; “neurosurgery” or “neurosurgical procedures” and “administration, topical” and “antibacterial agents.” Results: In the last 70 years, we have poorly studied the use of topical antibiotics in neurosurgery. All the papers reported were Class III evidence. Conclusion: To the best of our knowledge, there is no publication that provided Class I or II evidence about topical antibiotic prophylaxis in neurosurgery. PMID:20882106

Synchronizing Pharmacotherapy in Acne with Review of Clinical Care

PubMed Central

Sacchidanand, Sarvajnamurthy Aradhya; Lahiri, Koushik; Godse, Kiran; Patwardhan, Narendra Gajanan; Ganjoo, Anil; Kharkar, Rajendra; Narayanan, Varsha; Borade, Dhammraj; D’souza, Lyndon

2017-01-01

Acne is a chronic inflammatory skin disease that involves the pathogenesis of four major factors, such as androgen-induced increased sebum secretion, altered keratinization, colonization of Propionibacterium acnes, and inflammation. Several acne mono-treatment and combination treatment regimens are available and prescribed in the Indian market, ranging from retinoids, benzoyl peroxide (BPO), anti-infectives, and other miscellaneous agents. Although standard guidelines and recommendations overview the management of mild, moderate, and severe acne, relevance and positioning of each category of pharmacotherapy available in Indian market are still unexplained. The present article discusses the available topical and oral acne therapies and the challenges associated with the overall management of acne in India and suggestions and recommendations by the Indian dermatologists. The experts opined that among topical therapies, the combination therapies are preferred over monotherapy due to associated lower efficacy, poor tolerability, safety issues, adverse effects, and emerging bacterial resistance. Retinoids are preferred in comedonal acne and as maintenance therapy. In case of poor response, combination therapies BPO-retinoid or retinoid-antibacterials in papulopustular acne and retinoid-BPO or BPO-antibacterials in pustular-nodular acne are recommended. Oral agents are generally recommended for severe acne. Low-dose retinoids are economical and have better patient acceptance. Antibiotics should be prescribed till the inflammation is clinically visible. Antiandrogen therapy should be given to women with high androgen levels and are added to regimen to regularize the menstrual cycle. In late-onset hyperandrogenism, oral corticosteroids should be used. The experts recommended that an early initiation of therapy is directly proportional to effective therapeutic outcomes and prevent complications. PMID:28794543

Mesoporous TiO2 implants for loading high dosage of antibacterial agent

NASA Astrophysics Data System (ADS)

Park, Se Woong; Lee, Donghyun; Choi, Yong Suk; Jeon, Hoon Bong; Lee, Chang-Hoon; Moon, Ji-Hoi; Kwon, Il Keun

2014-06-01

We have fabricated mesoporous thin films composed of TiO2 nanoparticles on anodized titanium implant surfaces for loading drugs at high doses. Surface anodization followed by treatment with TiO2 paste leads to the formation of mechanically stable mesoporous thin films with controllable thickness. A series of antibacterial agents (silver nanoparticles, cephalothin, minocycline, and amoxicillin) were loaded into the mesoporous thin films and their antibacterial activities were evaluated against five bacterial species including three oral pathogens. Additionally, two agents (silver nanoparticles and minocycline) were loaded together on the thin film and tested for antibacterial effectiveness. The combination of silver nanoparticles and minocycline was found to display a wide range of effectiveness against all tested bacteria.

The role of topical moxifloxacin, a new antibacterial in Europe, in the treatment of bacterial conjunctivitis.

PubMed

Benitez-Del-Castillo, Jose; Verboven, Yves; Stroman, David; Kodjikian, Laurent

2011-01-01

This article discusses current practice in the treatment of conjunctivitis and how the use of topical moxifloxacin can increase therapeutic effectiveness, reduce treatment failures and, consequently, be cost effective and reduce the societal burden of the disorder. Current practice and effectiveness data were derived from the literature. Data on healthcare utilization as a result of treatment failure were collected by survey and the cost of treatment was defined using national costings. A decision-analytic model to assess cost effectiveness was developed and the impact on the healthcare budget was calculated to define the health economic impact. Bacterial conjunctivitis represents a significant health problem and accounts for an estimated 1-1.5% of primary-care consultations. The disorder is highly contagious and causes a substantial healthcare and societal burden. Bacterial conjunctivitis is generally self-limiting, resolving within 1-2 weeks. However, the use of antibacterials significantly improves clinical and microbiological remission, shortens symptom duration, and enables more effective use of healthcare resources, compared with placebo. From a health economic perspective this benefits the healthcare system and society, since fewer healthcare resources are needed and the adult affected, or the parent/caregiver of the child affected, can return to full work capacity sooner, reducing loss of productivity. Treatment strategies vary significantly between countries. Most patients are first seen in primary care, where 'wait-and-see', lubrification and antiseptic or antibacterial treatment is provided. In Europe, when antibacterials are prescribed most general practitioners (GPs) prescribe a broad-spectrum topical antibacterial. The most commonly used drugs are chloramphenicol and fusidic acid, with fluoroquinolones rarely reported as first-line treatment by GPs. At the specialist (ophthalmologist) level, or for second-line treatment at the GP level, topical antibacterials are frequently used. However, in most countries, topical fluoroquinolones, particularly those recently approved by the European Medicines Agency, such as topical levofloxacin and topical moxifloxacin, are rarely used and instead are reserved for use as a last resort. In other parts of the world topical lomefloxacin, gatifloxacin and/or besifloxacin are also available. The strategy of using novel topical fluoroquinolones as a last resort reflects a belief that the use of topical fluoroquinolones may enhance the development of resistance, jeopardizing future availability of antibacterial treatment for ocular infections. In fact, most cases of bacterial resistance arise as a result of systemic treatment. Thus, this concern should not be extrapolated to topical use of fluoroquinolones, which results in antibacterial concentrations at the ocular surface that can significantly exceed mutant prevention concentrations. In addition, with products such as topical moxifloxacin, a dual-step mutation is required for resistance to emerge. Moxifloxacin restricts the selection of resistant mutants, meaning that emergence of resistance is unlikely. The strategy of not using the most effective fluoroquinolones such as topical moxifloxacin may lead to more patients with no improvement or worsening of symptoms, requiring re-intervention, additional examination and new treatment; these outcomes are defined as 'treatment failures'. Treatment failures cause an extra societal burden and increased costs due to the extra healthcare resources required (additional GP/specialist visits, laboratory tests, additional treatment, etc.). Compared with non-fluoroquinolones, topical moxifloxacin has a higher potency and faster in vitro 'speed-to-kill'. It has also been shown that, within the fluoroquinolone class, topical moxifloxacin and besifloxacin achieve the highest mean concentrations in conjunctival tissue, have the longest residence times and display favourable area under the concentration-time curve from time zero to 24 hours (AUC(24))/minimum inhibitory concentration ratio required to inhibit the growth of 90% of organisms (MIC(90)) and thus favourable pharmacokinetic/pharmacodynamic characteristics. This can result in reduced time-to-cure and a lower number of treatment failures, leading to better disease management and a healthcare-economic benefit arising from the associated reduction in utilization of healthcare resources. The high potency and mean concentration in conjunctival tissue combined with the long residence time of topical moxifloxacin enables a dosing strategy of three times daily for 5 days. Topical moxifloxacin is also the first ophthalmic antibacterial in Europe provided as a multidose, self-preserved, topical solution, thus avoiding the risk of benzalkonium chloride preservative-related allergic reactions and swelling. In addition, topical moxifloxacin has a near neutral pH (6.8) and is well tolerated by patients. Given the characteristics of the novel topical fluoroquinolones, a change in the healthcare treatment strategy for acute infectious conjunctivitis is to be recommended. Topical application of fluoroquinolones, such as moxifloxacin multidose self-preserved solution, should be considered earlier in the treatment path for conjunctivitis. Notwithstanding the premium price attached to this novel topical antibacterial, use of topical moxifloxacin for bacterial conjunctivitis can be cost effective and even generate total healthcare budget savings by reducing both the costs of managing treatment failures and the use of clinicians' time to manage such failures.

Conclusions: the future of antimicrobial therapy - Augmentin and beyond.

PubMed

Ball, Peter

2007-12-01

Since most infectious microorganisms inevitably develop resistance to any agents used to combat them, there has been a constant need to produce improved, more potent, antimicrobials. At least in part, the emergence and spread of resistant organisms has been provoked by inappropriate over-use of antibacterials. In the last decade, many fewer new antibacterials have been developed but overall prescribing has continued to increase. Consensus prescribing principles have now been defined with the aim of optimising therapy and preventing further increases in, or even to prompt a reduction in, the prevalence of resistance to antibacterial agents. Whilst it is important to encourage continued development of new classes of antibacterials, it is also vital to make the best use of available agents. The development of new dosages and formulations of amoxicillin/clavulanate allows this agent to continue to fill the important role in therapy which it has occupied, and continues to occupy, 25 years after it was launched.

Dual antibacterial agents of nano-silver and 12-methacryloyloxydodecylpyridinium bromide in dental adhesive to inhibit caries

PubMed Central

Zhang, Ke; Li, Fang; Imazato, Satoshi; Cheng, Lei; Liu, Huaibing; Arola, Dwayne D.; Bai, Yuxing; Xu, Hockin H. K.

2013-01-01

Dental resins containing 12-methacryloyloxydodecylpyridinium bromide (MDPB) showed potent antibacterial functions. Recent studies developed antibacterial resins containing nanoparticles of silver (NAg). The objectives of this study were to develop an adhesive containing dual agents of MDPB and NAg for the first time, and to investigate the combined effects of antibacterial adhesive and primer on biofilm viability, metabolic activity, lactic acid, dentin bond strength, and fibroblast cytotoxicity. MDPB and NAg were incorporated into Scotchbond Multi-Purpose (SBMP) adhesive “A” and primer “P”. Five systems were tested: SBMP adhesive A; A+MDPB; A+NAg; A+MDPB+NAg; P+MDPB+NAg together with A+MDPB+NAg. Dental plaque microcosm biofilms were cultured using mixed saliva from ten donors. Metabolic activity, colony-forming units, and lactic acid production of biofilms were investigated. Human fibroblast cytotoxicity of bonding agents was determined. MDPB+NAg in adhesive/primer did not compromise dentin bond strength (p>0.1). MDPB or NAg alone in adhesive substantially reduced the biofilm activities. Dual agents MDPB+NAg in adhesive greatly reduced the biofilm viability compared to each agent alone (p<0.05). The greatest inhibition of biofilms was achieved when both adhesive and primer contained MDPB+NAg. Fibroblast viability of groups with dual antibacterial agents was similar to control using culture medium without resin eluents (p>0.1). In conclusion, this study showed for the first time that the antibacterial potency of MDPB adhesive could be substantially enhanced via NAg. Adding MDPB+NAg into both primer and adhesive achieved the strongest anti-biofilm efficacy. The dual agent (MDPB+NAg) method could have wide applicability to other adhesives, sealants, cements and composites to inhibit biofilms and caries. PMID:23529901

Antibacterial and remineralization effects of orthodontic bonding agents containing bioactive glass

PubMed Central

Kim, Dong-Hyun; Song, Chang Weon; Yoon, Seog-Young; Kim, Se-Yeon; Na, Hee Sam; Chung, Jin

2018-01-01

Objective The aim of this study was to evaluate the mechanical and biological properties of orthodontic bonding agents containing silver- or zinc-doped bioactive glass (BAG) and determine the antibacterial and remineralization effects of these agents. Methods BAG was synthesized using the alkali-mediated solgel method. Orthodontic bonding agents containing BAG were prepared by mixing BAG with flowable resin. Transbond™ XT (TXT) and Charmfil™ Flow (CF) were used as controls. Ion release, cytotoxicity, antibacterial properties, the shear bond strength, and the adhesive remnant index were evaluated. To assess the remineralization properties of BAG, micro-computed tomography was performed after pH cycling. Results The BAG-containing bonding agents showed no noticeable cytotoxicity and suppressed bacterial growth. When these bonding agents were used, demineralization after pH cycling began approximately 200 to 300 µm away from the bracket. On the other hand, when CF and TXT were used, all surfaces that were not covered by the adhesive were demineralized after pH cycling. Conclusions Our findings suggest that orthodontic bonding agents containing silver- or zinc-doped BAG have stronger antibacterial and remineralization effects compared with conventional orthodontic adhesives; thus, they are suitable for use in orthodontic practice. PMID:29732302

Acute exacerbations of chronic bronchitis: a pharmacoeconomic review of antibacterial use.

PubMed

Morris, Stephen; Anderson, Pippa; Irwin, Debra E

2002-01-01

Chronic bronchitis is a common problem affecting a large proportion of the adult population. People with chronic bronchitis are subject to recurrent attacks of bronchial inflammation called acute exacerbations of chronic bronchitis (AECBs). In patients with AECBs, symptoms may worsen due to a bacterial infection; the exacerbation is then known as an acute bacterial exacerbation of chronic bronchitis (ABECB). ABECBs are thought to be controllable through the use of antibacterial agents. In this paper we review current evidence on the cost of chronic bronchitis and AECBs, the cost effectiveness of antibacterials in the management of ABECB, and the factors that may affect the cost-effectiveness of antibacterials in the management of ABECB. We find that the number of economic evaluations conducted in this area is small. Of the few economic evaluations that have been conducted there has been only one prospective economic evaluation based on a clinical trial. The remainder are simple decision analysis-based modelling studies or retrospective database studies. Our principle findings are as follows: a key factor affecting the cost-effective use of antibacterials in the management of ABECB is the definitive diagnosis of the condition. Unfortunately, diagnosing a bacterial cause of an AECB is difficult, which presents problems in ensuring that antibacterials are not prescribed unnecessarily;current evidence suggests but does not prove that use of more effective but more costly first-line antibacterials may be relatively cost effective and may minimise overall expenditure by reducing the high costs associated with treatment failure;chronic bronchitis and AECB have a significant and negative physical and psychological effect on health-related quality of life. In conclusion, the small number of economic evaluations conducted in this area, coupled with the nature of the design of these studies, precludes a definitive statement recommending which specific antibacterial should be preferred on cost-effectiveness grounds for the management of ABECB. On the basis of our findings we suggest some topics for further research.

Silver nanoparticles: A new view on mechanistic aspects on antimicrobial activity.

PubMed

Durán, Nelson; Durán, Marcela; de Jesus, Marcelo Bispo; Seabra, Amedea B; Fávaro, Wagner J; Nakazato, Gerson

2016-04-01

Silver nanoparticles are well known potent antimicrobial agents. Although significant progresses have been achieved on the elucidation of antimicrobial mechanism of silver nanoparticles, the exact mechanism of action is still not completely known. This overview incorporates a retrospective of previous reviews published and recent original contributions on the progress of research on antimicrobial mechanisms of silver nanoparticles. The main topics discussed include release of silver nanoparticles and silver ions, cell membrane damage, DNA interaction, free radical generation, bacterial resistance and the relationship of resistance to silver ions versus resistance to silver nanoparticles. The focus of the overview is to summarize the current knowledge in the field of antibacterial activity of silver nanoparticles. The possibility that pathogenic microbes may develop resistance to silver nanoparticles is also discussed. Antibacterial effect of nanoscopic silver generated a lot of interest both in research projects and in practical applications. However, the exact mechanism is still will have to be elucidated. This overview incorporates a retrospective of previous reviews published from 2007 to 2013 and recent original contributions on the progress of research on antimicrobial mechanisms to summarize our current knowledge in the field of antibacterial activity of silver nanoparticles. Copyright © 2015 Elsevier Inc. All rights reserved.

Enhancing the Prevention and Treatment of Orthopaedic Infections Associated with Traumatic Injury

DTIC Science & Technology

2017-10-01

minipeg-2 derivative have antimicrobial activity in and of themselves (see previous progress report). This absence of antibacterial activity is not...necessarily desirable, as antibacterial activity of the targeting agent itself could prove useful. However, it does suggest that these agents are less...of the minipeg linker (BS-4-134 and BS-4-142). However, unlike our daptomycin conjugates, antibacterial activity was essentially abolished with all of

What is an "ideal" antibiotic? Discovery challenges and path forward.

PubMed

Singh, Sheo B; Young, Katherine; Silver, Lynn L

2017-06-01

An ideal antibiotic is an antibacterial agent that kills or inhibits the growth of all harmful bacteria in a host, regardless of site of infection without affecting beneficial gut microbes (gut flora) or causing undue toxicity to the host. Sadly, no such antibiotics exist. What exist are many effective Gram-positive antibacterial agents as well as broad-spectrum agents that provide treatment of certain Gram-negative bacteria but not holistic treatment of all bacteria. However effectiveness of all antibacterial agents is being rapidly eroded due to resistance. This viewpoint provides an overview of today's antibiotics, challenges and potential path forward of discovery and development of new (ideal) antibiotics. Copyright © 2017 Elsevier Inc. All rights reserved.

Extraction of chitosan from shrimp shells waste and application in antibacterial finishing of bamboo rayon.

PubMed

Teli, M D; Sheikh, Javed

2012-06-01

Chitosan can be best utilized as safe antibacterial agent for textiles but there is always a limitation of its durability. The chitin containing shellfish waste is available in huge quantities, but very low quantities are utilized for extraction of high value products like chitosan. In the current work chitosan was extracted from shrimp shells and then used as antibacterial exhaust finishing agent for grafted bamboo rayon. Chitosan bound bamboo rayon was then evaluated for antibacterial activity against both gram positive and gram negative bacteria. The product showed antibacterial activity against both types of bacterias which was durable till 30 washes. Copyright © 2012 Elsevier B.V. All rights reserved.

Formulation and Evaluation of Antibacterial Creams and Gels Containing Metal Ions for Topical Application

PubMed Central

Chen, Mei X.; Alexander, Kenneth S.

2016-01-01

Background. Skin infections occur commonly and often present therapeutic challenges to practitioners due to the growing concerns regarding multidrug-resistant bacterial, viral, and fungal strains. The antimicrobial properties of zinc sulfate and copper sulfate are well known and have been investigated for many years. However, the synergistic activity between these two metal ions as antimicrobial ingredients has not been evaluated in topical formulations. Objective. The aims of the present study were to (1) formulate topical creams and gels containing zinc and copper alone or in combination and (2) evaluate the in vitro antibacterial activity of these metal ions in the formulations. Method. Formulation of the gels and creams was followed by evaluating their organoleptic characteristics, physicochemical properties, and in vitro antibacterial activity against Escherichia coli and Staphylococcus aureus. Results. Zinc sulfate and copper sulfate had a strong synergistic antibacterial activity in the creams and gels. The minimum effective concentration was found to be 3 w/w% for both active ingredients against the two tested microorganisms. Conclusions. This study evaluated and confirmed the synergistic in vitro antibacterial effect of copper sulfate and zinc sulfate in a cream and two gels. PMID:27885352

Effect of water-ageing on dentine bond strength and anti-biofilm activity of bonding agent containing new monomer dimethylaminododecyl methacrylate

PubMed Central

Zhang, Ke; Cheng, Lei; Wu, Eric J.; Weir, Michael D.; Bai, Yuxing; Xu, Hockin H. K.

2013-01-01

Objectives The objectives of this study were to develop bonding agent containing a new antibacterial monomer dimethylaminododecyl methacrylate (DMADDM) as well as nanoparticles of silver (NAg) and nanoparticles of amorphous calcium phosphate (NACP), and to investigate the effects of water-ageing for 6 months on dentine bond strength and anti-biofilm properties for the first time. Methods Four bonding agents were tested: Scotchbond Multi-Purpose (SBMP) Primer and Adhesive control; SBMP + 5% DMADDM; SBMP + 5% DMADDM + 0.1% NAg; and SBMP + 5% DMADDM + 0.1% NAg with 20% NACP in adhesive. Specimens were water-aged for 1 d and 6 months at 37 °C. Then the dentine shear bond strengths were measured. A dental plaque microcosm biofilm model was used to inoculate bacteria on water-aged specimens and to measure metabolic activity, colony-forming units (CFUs), and lactic acid production. Results Dentine bond strength showed a 35% loss in 6 months of water-ageing for SBMP control (mean ± sd; n = 10); in contrast, the new antibacterial bonding agents showed no strength loss. The DMADDM–NAg–NACP containing bonding agent imparted a strong antibacterial effect by greatly reducing biofilm viability, metabolic activity and acid production. The biofilm CFU was reduced by more than two orders of magnitude, compared to SBMP control. Furthermore, the DMADDM–NAg–NACP bonding agent exhibited a long-term antibacterial performance, with no significant difference between 1 d and 6 months (p > 0.1). Conclusions Incorporating DMADDM–NAg–NACP in bonding agent yielded potent and long-lasting antibacterial properties, and much stronger bond strength after 6 months of water-ageing than a commercial control. The new antibacterial bonding agent is promising to inhibit biofilms and caries at the margins. The method of DMADDM–NAg–NACP incorporation may have a wide applicability to other adhesives, cements and composites. PMID:23583528

Inhibition of bacterial growth and intramniotic infection in a guinea pig model of chorioamnionitis using PAMAM dendrimers.

PubMed

Wang, Bing; Navath, Raghavendra S; Menjoge, Anupa R; Balakrishnan, Bindu; Bellair, Robert; Dai, Hui; Romero, Roberto; Kannan, Sujatha; Kannan, Rangaramanujam M

2010-08-16

Dendrimers have emerged as topical microbicides to treat vaginal infections. This study explores the in vitro, in vivo antimicrobial activity of PAMAM dendrimers, and the associated mechanism. Interestingly, topical cervical application of 500 microg of generation-4 neutral dendrimer (G(4)-PAMAM-OH) showed potential to treat the Escherichia coli induced ascending uterine infection in guinea pig model of chorioamnionitis. Amniotic fluid collected from different gestational sacs of infected guinea pigs posttreatment showed absence of E. coli growth in the cultures plated with it. The cytokine level [tumor necrosis factor (TNFalpha) and interleukin (IL-6 and IL-1beta)] in placenta of the G(4)-PAMAM-OH treated animals were comparable to those in healthy animals while these were notably high in infected animals. Since, antibacterial activity of amine-terminated PAMAM dendrimers is known, the activity of hydroxyl and carboxylic acid terminated PAMAM dendrimers was compared with it. Though the G(4)-PAMAM-NH(2) shows superior antibacterial activity, it was found to be cytotoxic to human cervical epithelial cell line above 10 microg/mL, while the G(4)-PAMAM-OH was non-cytotoxic up to 1mg/mL concentration. Cell integrity, outer (OM) and inner (IM) membrane permeabilization assays showed that G(4)-PAMAM-OH dendrimer efficiently changed the OM permeability, while G(4)-PAMAM-NH(2) and G(3.5)-PAMAM-COOH damaged both OM and IM causing the bacterial lysis. The possible antibacterial mechanism are G(4)-PAMAM-NH(2) acts as polycation binding to the polyanionic lipopolysaccharide in E. coli, the G(4)-PAMAM-OH forms hydrogen bonds with the hydrophilic O-antigens in E. coli membrane and the G(3.5)-PAMAM-COOH acts as a polyanion, chelating the divalent ions in outer cell membrane of E. coli. This is the first study which shows that G(4)-PAMAM-OH dendrimer acts as an antibacterial agent. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Novel cajaninstilbene acid derivatives as antibacterial agents.

PubMed

Geng, Zhi-Zhong; Zhang, Jian-Jun; Lin, Jing; Huang, Mei-Yan; An, Lin-Kun; Zhang, Hong-Bin; Sun, Ping-Hua; Ye, Wen-Cai; Chen, Wei-Min

2015-07-15

Discovery of novel antibacterial agents with new structural scaffolds that combat drug-resistant pathogens is an urgent task. Cajaninstilbene acid, which is isolated from pigeonpea leaves, has shown antibacterial activity. In this study, a series of cajaninstilbene acid derivatives were designed and synthesized. The antibacterial activities of these compounds against gram-negative and gram-positive bacteria, as well as nine strains of methicillin-resistant staphylococcus aureus (MRSA) bacteria are evaluated，and the related structure-activity relationships are discussed. Assays suggest that some of the synthetic cajaninstilbene acid derivatives exhibit potent antibacterial activity against gram-positive bacterial strains and MRSA. Among these compounds, 5b, 5c, 5j and 5k show better antibacterial activity than the positive control compounds. The results of MTT assays illustrate the low cytotoxicity of the active compounds. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Pleuromutilin and its derivatives-the lead compounds for novel antibiotics.

PubMed

Tang, Y-Z; Liu, Y-H; Chen, J-X

2012-01-01

Due to the rapid onset of resistance to most antibacterial drugs, research efforts are focusing on new classes of antibacterials with different mechanisms of action from clinically used antibacterials. Pleuromutilin derivatives have received more and more scientific attention for their unique mechanism of action. Two pleuromutilin derivatives, tiamulin and valnemulin have been successfully developed as antibiotics for veterinary use. Retapamulin, another pleuromutilin derivative has been approved for use in humans in April 2007 by Food and Drug Administration (FDA). It has been shown that there is rarely cross-resistance between pleuromutilin derivatives and other antimicrobial agents, and the development of resistance bacterial is still low. This review will demonstrate mechanism of action of pleuromutilin derivatives and reveal the structure-activity relationship (SAR) of pleuromutilin derivatives. Additionally, the pleuromutilin antibacterial derivative agents in the market, such as tiamulin, valnemulin and retapamulin, will be discussed. It is proposed that new antibacterial agents might be developed from pleuromutilin derivatives in the future.

Synthesis and Bioactivity Evaluation of Novel 2-Salicyloylbenzofurans as Antibacterial Agents.

PubMed

Phan, Phuong-Thuy T; Nguyen, Thu-Trang T; Nguyen, Hong-Nhung T; Le, Bao-Khanh N; Vu, Thao T; Tran, Dong C; Pham, Tuan-Anh N

2017-04-25

In order to discover new antibacterial agents, series of 2-salicyloylbenzofuran derivatives were designed, synthesized and evaluated for their antibacterial activities against three Gram-(+) strains (methicillin-sensitive Staphylococcus aureus (MSSA) ATCC 29213, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, and Streptococcus faecalis ( S. faecalis ) ATCC 29212) and one Gram-(-) strain ( Escherichia coli (E. coli) ATCC 25922). The 2-salicyloylbenzofuran heterocycles were generated by Rap-Stoermer condensation of salicylaldehydes with phenacyl bromides and then converted to diverse O -ether derivatives by Williamson synthesis. The targeted products were screened for in vitro qualitative (zone of inhibition) and quantitative (MIC) antibacterial activities by agar well diffusion assay and agar dilution method. Amongst the compounds, those bearing carboxylic acid functional group were found to exhibit reasonable activity against Gram-(+) bacterial strains including S. faecalis , MSSA and MRSA with the most potent antibacterial agent 8h (MICs = 0.06-0.12 mM). Besides, the 2-salicyloylbenzofurans partly displayed inhibitory activity against MRSA with the best MICs = 0.14 mM ( 8f ) and 0.12 mM ( 8h ). Finally, the antibacterial results preliminarily suggested that the substituent bearing carboxylic acid group at salicyloyl-C2 and the bromine atoms on the benzofuran moiety seem to be the functionality necessary for antibacterial activities.

Natural and ion-exchanged illite clays reduce bacterial burden and inflammation in cutaneous meticillin-resistant Staphylococcus aureus infections in mice

PubMed Central

Otto, Caitlin C.; Kilbourne, Jacquelyn

2016-01-01

Discoveries associated with antibacterial activity of hydrated clays necessitate assessments of in vivo efficacy, practical use and safety. Surface properties of clays can lead to variations in the composition and abundance of bound compounds or ions, thus affecting antibacterial activity. Since exchangeable metal ions released from the clay surface are responsible for in vitro antibacterial activity, we evaluated the in vivo antibacterial efficacy of four natural clays (one illite clay, two montmorillonite clays and one kaolinite clay) and three ion-exchanged, antibacterial clays against superficial, cutaneous meticillin-resistant Staphylococcus aureus (MRSA) infections in mice. Superficial, cutaneous wounds on the back of SKH1-Elite mice were generated and subsequently infected with MRSA. Following twice daily applications of a hydrated clay poultice to infected wounds for 7 days, we observed significant differences in the in vivo antibacterial efficacy between different types of clays. The natural and ion-exchanged illite clays performed best, as measured by bacterial load, inflammatory response and gross wound morphology with significant decreases in bacterial viability and dermatitis. Topical application of kaolinite clay was the least effective, resulting in the lowest decrease in bacterial load and exhibiting severe dermatitis. These data suggest that specific types of clays may offer a complementary and integrative strategy for topically treating MRSA and other cutaneous infections. However, since natural clays exhibit in vitro antibacterial variability and vary vastly in surface chemistries, adsorptive/absorptive characteristics and structural composition, the properties and characteristics of illite clays could aid in the development of standardized and customized aluminosilicates for topical infections. PMID:26508716

Similarities and Differences between Silver Ions and Silver in Nanoforms as Antibacterial Agents

PubMed Central

Kędziora, Anna; Speruda, Mateusz; Rybka, Jacek; Łukowiak, Anna; Bugla-Płoskońska, Gabriela

2018-01-01

Silver is considered as antibacterial agent with well-known mode of action and bacterial resistance against it is well described. The development of nanotechnology provided different methods for the modification of the chemical and physical structure of silver, which may increase its antibacterial potential. The physico-chemical properties of silver nanoparticles and their interaction with living cells differs substantially from those of silver ions. Moreover, the variety of the forms and characteristics of various silver nanoparticles are also responsible for differences in their antibacterial mode of action and probably bacterial mechanism of resistance. The paper discusses in details the aforementioned aspects of silver activity. PMID:29393866

Antibacterial activity in adhesive dentistry: a literature review.

PubMed

Shafiei, Fereshteh; Memarpour, Mahtab

2012-01-01

This literature review summarizes the published research regarding the antibacterial agents used in adhesive dentistry. This article provides information about the clinical applications, beneficial effects, and possible disadvantages of antibacterials when used in various bonding situations.

In vitro synergism of magnolol and honokiol in combination with antibacterial agents against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Zuo, Guo-Ying; Zhang, Xin-Juan; Han, Jun; Li, Yu-Qing; Wang, Gen-Chun

2015-12-01

Methicillin-resistant Staphylococcus aureus (MRSA) is a problematic pathogen posing a serious therapeutic challenge in the clinic. It is often multidrug-resistant (MDR) to conventional classes of antibacterial agents and there is an urgent need to develop new agents or strategies for treatment. Magnolol (ML) and honokiol (HL) are two naturally occurring diallylbiphenols which have been reported to show inhibition of MRSA. In this study their synergistic effects with antibacterial agents were further evaluated via checkerboard and time-kill assays. The susceptibility spectrum of clinical MRSA strains was tested by the disk diffusion method. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of ML and HL were assayed by broth microdilution. The synergy was evaluated through checkerboard microdilution and time-killing experiments. ML and HL showed similar activity against both MSSA and MRSA with MIC/MBC at 16 ~ 64 mg/L, with potency similar to amikacin (AMK) and gentamicin (GEN). When they were used in combination with conventional antibacterial agents, they showed bacteriostatic synergy with FICIs between 0.25 ~ 0.5, leading to the combined MICs decreasing to as low as 1 ~ 2 and 1 ~ 16 mg/L for ML (HL) and the agents, respectively. MIC50 of the combinations decreased from 16 mg/L to 1 ~ 4 mg/L for ML (HL) and 8 ~ 128 mg/L to 2 ~ 64 mg/L for the antibacterial agents, which exhibited a broad spectrum of synergistic action with aminoglycosides (AMK, etilmicin (ETM) and GEN), floroquinolones (levofloxacin (LEV), ciprofloxacin and norfloxacin), fosfomycin (FOS) and piperacillin. The times of dilution (TOD, the extent of decreasing in MIC value) were determined up to 16 for the combined MIC. A more significant synergy after combining was determined as ML (HL) with AMK, ETM, GEN and FOS. ML (HL) combined with antibacterial agents did not show antagonistic effects on any of the ten MRSA strains. Reversal effects of MRSA resistance to AMK and GEN by ML and HL were also observed, respectively. All the combinations also showed better dynamic bactericidal activity against MRSA than any of single ML (HL) or the agents at 24 h incubation. The more significant synergy of combinations were determined as HL (ML) + ETM, HL + LEV and HL + AMK (GEN or FOS), with △LC24 of 2.02 ~ 2.25. ML and HL showed synergistic potentiation of antibacterial agents against clinical isolates of MRSA and warrant further pharmacological investigation.

The biology of Mur ligases as an antibacterial target.

PubMed

Kouidmi, Imène; Levesque, Roger C; Paradis-Bleau, Catherine

2014-10-01

With antibiotic resistance mechanisms increasing in diversity and spreading among bacterial pathogens, the development of new classes of antibacterial agents against judiciously chosen targets is a high-priority task. The biochemical pathway for peptidoglycan biosynthesis is one of the best sources of antibacterial targets. Within this pathway are the Mur ligases, described in this review as highly suitable targets for the development of new classes of antibacterial agents. The amide ligases MurC, MurD, MurE and MurF function with the same catalytic mechanism and share conserved amino acid regions and structural features that can conceivably be exploited for the design of inhibitors that simultaneously target more than one enzyme. This would provide multi-target antibacterial weapons with minimized likelihood of target-mediated resistance development. © 2014 John Wiley & Sons Ltd.

[New antibacterial agents on the market and in the pipeline].

PubMed

Kern, W V

2015-11-01

After some years of stagnation there have been several new successful developments in the field of antibacterial agents. Most of these new developments have been in conventional antibacterial classes. New drugs among the beta-lactam agents are methicillin-resistant Staphylococcus aureus (MRSA) active cephalosporins (ceftaroline and ceftobiprole) and new combinations of beta-lactam with beta-lactamase inhibitors (ceftolozane/tazobactam, ceftazidime/avibactam, imipenem/relebactam and meropenem/RPX7009). New developments can also be observed among oxazolidinones (tedizolid, radezolid, cadazolid and MRX-I), macrolides/ketolides (modithromycin and solithromycin), aminoglycosides (plazomicin), quinolones (nemonoxacin, delafloxacin and avarofloxacin), tetracyclines (omadacycline and eravacycline) as well as among glycopeptides and lipopeptides (oritavancin, telavancin, dalbavancin and surotomycin). New agents in a very early developmental phase are FabI inhibitors, endolysines, peptidomimetics, lipid A inhibitors, methionyl-tRNA synthetase inhibitors and teixobactin.

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

PubMed Central

Dewal, Mahender B.; Wani, Amit S.; Vidaillac, Celine; Oupicky, David; Rybak, Michael J.

2012-01-01

Several thieno[2,3-d]pyrimidinediones have been synthesized and examined for antibacterial activity against a range of Gram-positive and Gram-negative pathogens. Two compounds displayed potent activity (2–16 mg/L) against multi-drug resistant Gram-positive organisms, including methicillin, vancomycin-intermediate, and vancomycin-resistant Staphylococcus aureus (MRSA, VISA, VRSA) and vancomycin-resistant enterococci (VRE). Only one of these agents possessed moderate activity (16–32 mg/L) against Gram-negative strains. An examination of the cytotoxicity of these agents revealed that they displayed low toxicity (40–50 mg/L) against mammalian cell and very low hemolytic activity (2–7%). Taken together, these studies suggest that thieno[2,3-d]pyrimidinediones are interesting scaffolds for the development of novel Gram-positive antibacterial agents. PMID:22405289

Recent Development of Benzimidazole-Containing Antibacterial Agents.

PubMed

Song, Di; Ma, Shutao

2016-04-05

Clinically significant antibiotic resistance is one of the greatest challenges of the twenty-first century. However, new antibacterial agents are currently being developed at a much slower pace than our growing need for such drugs. Given their diverse biological activities and clinical applications, many bioactive heterocyclic compounds containing a benzimidazole nucleus have been the focus of interest for many researchers. The benzimidazole nucleus is a structural isostere of naturally occurring nucleotides. This advantage allows benzimidazoles to readily interact with the various biopolymers found in living systems. In view of this situation, much attention has been given to the exploration of benzimidazole-based antibacterial agents, leading to the discovery of many new chemical entities with intriguing profiles. In this minireview we summarize novel benzimidazole derivatives active against various bacterial strains. In particular, we outline the relationship between the structures of variously modified benzimidazoles and their antibacterial activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cost-effectiveness and Pricing of Antibacterial Drugs

PubMed Central

Verhoef, Talitha I; Morris, Stephen

2015-01-01

Growing resistance to antibacterial agents has increased the need for the development of new drugs to treat bacterial infections. Given increasing pressure on limited health budgets, it is important to study the cost-effectiveness of these drugs, as well as their safety and efficacy, to find out whether or not they provide value for money and should be reimbursed. In this article, we systematically reviewed 38 cost-effectiveness analyses of new antibacterial agents. Most studies showed the new antibacterial drugs were cost-effective compared to older generation drugs. Drug pricing is a complicated process, involving different stakeholders, and has a large influence on cost-effectiveness. Value-based pricing is a method to determine the price of a drug at which it can be cost-effective. It is currently unclear what the influence of value-based pricing will be on the prices of new antibacterial agents, but an important factor will be the definition of ‘value’, which as well as the impact of the drug on patient health might also include other factors such as wider social impact and the health impact of disease. PMID:25521641

Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles.

PubMed

Daima, Hemant K; Selvakannan, P R; Kandjani, Ahmad E; Shukla, Ravi; Bhargava, Suresh K; Bansal, Vipul

2014-01-21

We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPs(Y)) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.

Antimicrobial activity of topically-applied soyaethyl morpholinium ethosulfate micelles against Staphylococcus species.

PubMed

Yang, Shih-Chun; Aljuffali, Ibrahim A; Sung, Calvin T; Lin, Chwan-Fwu; Fang, Jia-You

2016-03-01

Here we evaluated the antibacterial efficacy of soyaethyl morpholinium ethosulfate (SME) micelles as an inherent bactericide against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). The antimicrobial activity was examined by in vitro culture model and murine model of skin infection. Cationic micelles formed by benzalkonium chloride or cetylpyridinium chloride were used for comparison. The minimum inhibitory concentration and minimum bactericidal concentration against S. aureus and MRSA were 1.71-3.42 and 1.71-6.84 μg/ml, respectively. Topical administration of SME micelles significantly decreased the cutaneous infection and MRSA load in mice. The killing of bacteria was caused by direct cell wall/membrane rupture. SME micelles also penetrated into the bacteria to elicit a Fenton reaction and oxidative stress. SME micelles have potential as antimicrobial agents due to their lethal effect against S. aureus and MRSA with a low toxicity to mammalian cells.

Application of cow milk-derived carbon dots/Ag NPs composite as the antibacterial agent

NASA Astrophysics Data System (ADS)

Han, Shuai; Zhang, He; Xie, Yujie; Liu, Liangliang; Shan, Changfu; Li, Xiangkai; Liu, Weisheng; Tang, Yu

2015-02-01

Cow milk-derived carbon dots (CMCDs) were prepared by hydrothermal treatment of cow milk, and the as-prepared CMCDs were further extracted by ethyl acetate to obtain amphiphilic CMCDs (ACMCDs). Using the ACMCDs both as a reducing agent and a template, the ACMCDs-supported silver nanoparticles (ACMCD-Ag nanocomposites) were prepared, which showed good biocidal effect on both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterias. After that, a novel ACMCD-Ag/polymethylmethacrylate nanocomposite antibacterial film was fabricated by solvent casting method. Due to the excellent antibacterial, light admitting, and flexible properties, the nanocomposite antibacterial film is considered to be of great potential in applications.

[Mutant prevention concentrations of antibacterial agents to ocular pathogenic bacteria].

PubMed

Liang, Qing-Feng; Wang, Zhi-Qun; Li, Ran; Luo, Shi-Yun; Deng, Shi-Jing; Sun, Xu-Guang

2009-01-01

To establish a method to measure mutant prevention concentration (MPC) in vitro, and to measure MPC of antibacterial agents for ocular bacteria caused keratitis. It was an experimental study. Forty strains of ocular bacteria were separated from cornea in Beijing Institute of Ophthalmology, which included 8 strains of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Pseudomonas aeruginosa and Klebsiella pneumoniae respectively. The minimal inhibitory concentration (MIC) of the levofloxacin (LVF), ofloxacin (OFL), ciprofloxacin (CIP), norfloxacin (NFL), tobramycin (TOB) and chloromycetin (CHL) were determined by agar dilution method from National Committee of Clinical Laboratory Standard (NCCLS). The MPC were measured by accumulate-bacterial methods with bacterial population inoculated more than 1.2 x 10(10) colony forming units per milliliter with Mueller-Hinton broth and tryptic soy agar plate. With the software of SPSS 11.0, the datum such as the range of MIC, MPC, MIC90 and MPC90 were calculated, and the selection index (MPC90/ MI90) and mutant selection window (MSW) were obtained. The MI90 of LVF and TOB (4 mg/L) to Staphylococcus aureus strains were the lowest. CIP showed the lowest MIC90 (0.25 mg/L) to Pseudomonas aeruginosa among six kinds of antibacterial agents. The MIC90 of LVF to Staphylococcus epidermidis (256 mg/L), Streptococcus pneumoniae (1 mg/L) and Klebsiella pneumoniae (0.25 mg/L) were lower than other antibacterial agents. The MPC90, MSW and the MPC90/MIC90 of levofloxacin showed lower values compared with other antibacterial medicines. From all the datum, the MIC90 of CHL was the highest and the activity was the weakest. Although the activity of LVF was higher to every kind of bacteria, CIP had the highest activity antibacterial to Pseudomonas aeruginosa. The capacity of CHL and TOB was weaker than Quinolones for restricting resistant mutants on ocular bacteria. LVF had the strongest capacity for restricting resistant mutants among Quinolones. LVF has better antibacterial effects and stronger capacity for restricting the selection of resistant mutants on ocular bacteria than other antibacterial agents.

Effect of salivary pellicle on antibacterial activity of novel antibacterial dental adhesives using a dental plaque microcosm biofilm model

PubMed Central

Li, Fang; Weir, Michael D.; Fouad, Ashraf F.; Xu, Hockin H.K.

2014-01-01

Objectives Antibacterial primer and adhesive are promising to inhibit biofilms and caries. Since restorations in vivo are exposed to saliva, one concern is the attenuation of antibacterial activity due to salivary pellicles. The objective of this study was to investigate the effects of salivary pellicles on bonding agents containing a new monomer dimethylaminododecyl methacrylate (DMADDM) or nanoparticles of silver (NAg) against biofilms for the first time. Methods DMADDM and NAg were synthesized and incorporated into Scotchbond Multi-Purpose adhesive and primer. Specimens were either coated or not coated with salivary pellicles. A microcosm biofilm model was used with mixed saliva from ten donors. Two types of culture medium were used: an artificial saliva medium (McBain), and Brain Heart Infusion (BHI) medium without salivary proteins. Metabolic activity, colony-forming units (CFU), and lactic acid production of plaque microcosm biofilms were measured (n = 6). Results Bonding agents containing DMADDM and NAg greatly inhibited biofilm activities, even with salivary pellicles. When using BHI, the pre-coating of salivary pellicles on resin surfaces significantly decreased the antibacterial effect (p < 0.05). When using artificial saliva medium, pre-coating of salivary pellicles on resin did not decrease the antibacterial effect. These results suggest that artificial saliva yielded medium-derived pellicles on resin surfaces, which provided attenuating effects on biofilms similar to salivary pellicles. Compared with the commercial control, the DMADDM-containing bonding agent reduced biofilm CFU by about two orders of magnitude. Significance Novel DMADDM- and NAg-containing bonding agents substantially reduced biofilm growth even with salivary pellicle coating on surfaces, indicating a promising usage in saliva-rich environment. DMADDM and NAg may be useful in a wide range of primers, adhesives and other restoratives to achieve antibacterial and anti-caries capabilities. PMID:24332270

Effect of salivary pellicle on antibacterial activity of novel antibacterial dental adhesives using a dental plaque microcosm biofilm model.

PubMed

Li, Fang; Weir, Michael D; Fouad, Ashraf F; Xu, Hockin H K

2014-02-01

Antibacterial primer and adhesive are promising to inhibit biofilms and caries. Since restorations in vivo are exposed to saliva, one concern is the attenuation of antibacterial activity due to salivary pellicles. The objective of this study was to investigate the effects of salivary pellicles on bonding agents containing a new monomer dimethylaminododecyl methacrylate (DMADDM) or nanoparticles of silver (NAg) against biofilms for the first time. DMADDM and NAg were synthesized and incorporated into Scotchbond Multi-Purpose adhesive and primer. Specimens were either coated or not coated with salivary pellicles. A microcosm biofilm model was used with mixed saliva from ten donors. Two types of culture medium were used: an artificial saliva medium (McBain), and Brain Heart Infusion (BHI) medium without salivary proteins. Metabolic activity, colony-forming units (CFU), and lactic acid production of plaque microcosm biofilms were measured (n=6). Bonding agents containing DMADDM and NAg greatly inhibited biofilm activities, even with salivary pellicles. When using BHI, the pre-coating of salivary pellicles on resin surfaces significantly decreased the antibacterial effect (p<0.05). When using artificial saliva medium, pre-coating of salivary pellicles on resin did not decrease the antibacterial effect. These results suggest that artificial saliva yielded medium-derived pellicles on resin surfaces, which provided attenuating effects on biofilms similar to salivary pellicles. Compared with the commercial control, the DMADDM-containing bonding agent reduced biofilm CFU by about two orders of magnitude. Novel DMADDM- and NAg-containing bonding agents substantially reduced biofilm growth even with salivary pellicle coating on surfaces, indicating a promising usage in saliva-rich environment. DMADDM and NAg may be useful in a wide range of primers, adhesives and other restoratives to achieve antibacterial and anti-caries capabilities. Published by Elsevier Ltd.

Preparation and characterization of silver chloride nanoparticles as an antibacterial agent

NASA Astrophysics Data System (ADS)

Duong Trinh, Ngoc; Thanh Binh Nguyen, Thi; Hai Nguyen, Thanh

2015-12-01

Silver chloride nanoparticles were prepared by the precipitation reaction between silver nitrate and sodium chloride in an aqueous solution containing poly(vinyl alcohol) as a stabilizing agent. Different characteristics of the nanoparticles in suspension and in lyophilized powder such as size, morphology, chemical nature, interaction with stabilizing agent and photo-stability were investigated. Biological tests showed that the obtained silver chloride nanoparticles displayed antibacterial activities against Escherichia coli and Staphylococcus aureus.

Polymeric micellar nanoplatforms for Fenton reaction as a new class of antibacterial agents.

PubMed

Park, Seong-Cheol; Kim, Nam-Hong; Yang, Wonseok; Nah, Jae-Woon; Jang, Mi-Kyeong; Lee, Dongwon

2016-01-10

Reactive oxygen species (ROS) produced by host phagocytes exert antibacterial action against a variety of pathogens and ROS-induced oxidative stress is the governing mechanism for the antibacterial activity of major bactericidal antibiotics. In particular, hydroxyl radical is a strong and nonselective oxidant which can damage biomolecules such as DNA, proteins and lipids. Ferrous ion is known to convert mild oxidant hydrogen peroxide (H2O2) into highly reactive and toxic hydroxyl radicals, referred to as Fenton reaction. Herein, we report a new class of antibacterial agents based on Fenton reaction-performing nanostructures, composed of H2O2-generating polymer (PCAE) and iron-containing ferrocene. Amphiphilic PCAE was designed to incorporate H2O2-generating cinnamaldehyde through acid-cleavable linkages and self-assemble to form thermodynamically stable micelles which could encapsulate ferrocene in their hydrophobic core. All the experiments in vitro display that ferrocene-loaded PCAE micelles produce hydroxyl radicals to kill Escherichia coli and Pseudomonas aeruginosa through membrane damages. Intraperitoneally injected ferrocene-loaded PCAE micelles significantly reduced the lung damages and therefore increased the survival rate of mice infected with drug resistant P. aeruginosa. Given their potent antibacterial activity, ferrocene-loaded PCAE micelles hold great potential as a new class of ROS-manipulating antibacterial agents. Copyright © 2015 Elsevier B.V. All rights reserved.

Enzyme-coated mesoporous silica nanoparticles as efficient antibacterial agents in vivo.

PubMed

Li, Li-Li; Wang, Hao

2013-10-01

Despite the fact that pathogenic infections are widely treated by antibiotics in the clinic nowadays, the increasing risk of multidrug-resistance associated with abuse of antibiotics is becoming a major concern in global public health. The increased death toll caused by pathogenic bacterial infection calls for effective antibiotic alternatives. Lysozyme-coated mesoporous silica nanoparticles (MSNs⊂Lys) are reported as antibacterial agents that exhibit efficient antibacterial activity both in vitro and in vivo with low cytotoxicity and negligible hemolytic side effect. The Lys corona provides multivalent interaction between MSNs⊂Lys and bacterial walls and consequently raises the local concentration of Lys on the surface of cell walls, which promotes hydrolysis of peptidoglycans and increases membrane-perturbation abilities. The minimal inhibition concentration (MIC) of MSNs⊂Lys is fivefold lower than that of free Lys in vitro. The antibacterial efficacy of MSNs⊂Lys is evaluated in vivo by using an intestine-infected mouse model. Experimental results indicate that the number of bacteria surviving in the colon is three orders of magnitude lower than in the untreated group. These natural antibacterial enzyme-modified nanoparticles open up a new avenue for design and synthesis of next-generation antibacterial agents as alternatives to antibiotics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibacterial activities of tellurium nanomaterials.

PubMed

Lin, Zong-Hong; Lee, Chia-Hsin; Chang, Hsin-Yun; Chang, Huan-Tsung

2012-05-01

We prepared four differently shaped Te nanomaterials (NMs) as antibacterial reagents against Escherichia coli. By controlling the concentrations of hydrazine (N(2)H(4)) as reducing agent, NaCl, and temperature, we prepared Te nanowires, nanopencils, nanorices, and nanocubes. These four Te NMs resulted in a live/dead ratio of E. coli cells of less than 0.1, which is smaller than that of Ag nanoparticles. The order of antibacterial activity against E. coli is nanocubes ≈ nanorices > nanopencils ≈ nanowires. This is in good agreement with the concentration order of tellurite (TeO(3)(2-)) ions released from Te NMs in E. coli cells, revealing that TeO(3)(2-) ions account for the antibacterial activity of the four Te NMs. We found that spherical Te nanoparticles (32 nm in diameter) with TeO(3)(2-) ions were formed in the E. coli cells. Compared to Ag nanoparticles that are commonly used as antibacterial reagents, Te NMs have higher antibacterial activity and lower toxicity. Thus, Te NMs hold great practical potential as a new and efficient antibacterial agent. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Corneal anesthetic abuse and Candida keratitis.

PubMed

Chern, K C; Meisler, D M; Wilhelmus, K R; Jones, D B; Stern, G A; Lowder, C Y

1996-01-01

Topical corneal anesthetic abuse is a self-inflicted injury, causing profound corneal morbidity. Superimposed infection is an important complicating factor. The authors report four patients with confirmed topical anesthetic abuse of the cornea, in whom Candida keratitis developed. A retrospective review of the medical records of four patients with confirmed topical corneal anesthetic abuse and fungal keratitis. A 21-year-old woman, two 28-year-old women, and a 35-year-old man were included in the study. All these patients sustained a corneal injury, prompting the chronic use of topical anesthetics (0.5% proparacaine hydrochloride in 3 patients, and 0.5% tetracaine hydrochloride and 0.4% benoxinate hydrochloride in the other). Corneal findings included epithelial defects in all patients, focal infiltrate in one patient, and ring-shaped stromal infiltrate in three patients. Topical anesthetic was discontinued, all patients initially were treated empirically with antibacterial agents, and three patients received topical corticosteroids. Subsequent corneal cultures grew Candida spp, Candida albicans specifically in three patients, and local and systemic antifungal therapy was started. Corneas in two patients re-epithelialized; a conjunctival flap was performed on another patient with a descemetocele; and the remaining patient was lost to follow-up, although repeat fungal cultures yielded no growth. Corneal superinfection with Candida may occur during topical anesthetic abuse. Therapy includes discontinuation of the anesthetic and institution of antifungal therapy.

Fabrication of Te and Te-Au Nanowires-Based Carbon Fiber Fabrics for Antibacterial Applications

PubMed Central

Chou, Ting-Mao; Ke, Yi-Yun; Tsao, Yu-Hsiang; Li, Ying-Chun; Lin, Zong-Hong

2016-01-01

Pathogenic bacteria that give rise to diseases every year remain a major health concern. In recent years, tellurium-based nanomaterials have been approved as new and efficient antibacterial agents. In this paper, we developed the approach to directly grow tellurium nanowires (Te NWs) onto commercial carbon fiber fabrics and demonstrated their antibacterial activity. Those Te NWs can serve as templates and reducing agents for gold nanoparticles (Au NPs) to deposit. Three different Te-Au NWs with varied concentration of Au NPs were synthesized and showed superior antibacterial activity and biocompability. These results indicate that the as-prepared carbon fiber fabrics with Te and Te-Au NWs can become antimicrobial clothing products in the near future. PMID:26861380

Phenazine antibiotic inspired discovery of potent bromophenazine antibacterial agents against Staphylococcus aureus and Staphylococcus epidermidis.

PubMed

Borrero, Nicholas V; Bai, Fang; Perez, Cristian; Duong, Benjamin Q; Rocca, James R; Jin, Shouguang; Huigens, Robert W

2014-02-14

Nearly all clinically used antibiotics have been (1) discovered from microorganisms (2) using phenotype screens to identify inhibitors of bacterial growth. The effectiveness of these antibiotics is attributed to their endogenous roles as bacterial warfare agents against competing microorganisms. Unfortunately, every class of clinically used antibiotic has been met with drug resistant bacteria. In fact, the emergence of resistant bacterial infections coupled to the dismal pipeline of new antibacterial agents has resulted in a global health care crisis. There is an urgent need for innovative antibacterial strategies and treatment options to effectively combat drug resistant bacterial pathogens. Here, we describe the implementation of a Pseudomonas competition strategy, using redox-active phenazines, to identify novel antibacterial leads against Staphylococcus aureus and Staphylococcus epidermidis. In this report, we describe the chemical synthesis and evaluation of a diverse 27-membered phenazine library. Using this microbial warfare inspired approach, we have identified several bromophenazines with potent antibacterial activities against S. aureus and S. epidermidis. The most potent bromophenazine analogue from this focused library demonstrated a minimum inhibitory concentration (MIC) of 0.78-1.56 μM, or 0.31-0.62 μg mL(-1), against S. aureus and S. epidermidis and proved to be 32- to 64-fold more potent than the phenazine antibiotic pyocyanin in head-to-head MIC experiments. In addition to the discovery of potent antibacterial agents against S. aureus and S. epidermidis, we also report a detailed structure-activity relationship for this class of bromophenazine small molecules.

New Paradigm Shift for the Green Synthesis of Antibacterial Silver Nanoparticles Utilizing Plant Extracts

PubMed Central

2014-01-01

This review covers general information regarding the green synthesis of antibacterial silver nanoparticles. Owing to their antibacterial properties, silver nanoparticles are widely used in many areas, especially biomedical applications. In green synthesis practices, the chemical reducing agents are eliminated, and biological entities are utilized to convert silver ions to silver nanoparticles. Among the various biological entities, natural plant extracts have emerged as green reducing agents, providing eco-friendly routes for the preparation of silver nanomaterials. The most obvious merits of green synthesis are the increased biocompatibility of the resulting silver nanoparticles and the ease with which the reaction can be carried out. This review summarizes some of the plant extracts that are used to produce antibacterial silver nanoparticles. Additionally, background information regarding the green synthesis and antibacterial activity of silver nanoparticles is provided. Finally, the toxicological aspects of silver nanoparticles are briefly mentioned. PMID:25343010

Development of Novel Antibiotics for the Treatment of Acinetobacter and Related Pathogens

DTIC Science & Technology

2012-07-07

1 was determined against liquid culture of each bacterial strain as recommended by the CLSI guidelines.අ Figure 1. Antibacterial activity of ABTZ...to enhance antibacterial activity were incorporated into compounds 28 and 29, and those known to attenuate antibacterial activity were incorporated ...Project objectives Our objectives were to identify novel antibacterial agents and strategies for the treatment of problematic bacterial pathogens

Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles

NASA Astrophysics Data System (ADS)

Daima, Hemant K.; Selvakannan, P. R.; Kandjani, Ahmad E.; Shukla, Ravi; Bhargava, Suresh K.; Bansal, Vipul

2013-12-01

We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPsY) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPsY) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials. Electronic supplementary information (ESI) available: XRD analysis (Fig. S1); cytotoxicity profile (Fig. S2) and optical images of human PC3 cells (Fig. S3) treated with nanomaterials; FTIR vibrational modes arising from different materials (Table S1); and relative concentrations of Ag and POMs present in modified AgNPs used for biological studies (Table S2). See DOI: 10.1039/c3nr03806h

Antibacterial efficiency of the Sudanese Roselle (Hibiscus sabdariffa L.), a famous beverage from Sudanese folk medicine.

PubMed

Abdallah, Emad Mohamed

2016-01-01

Hibiscus sabdariffa L. is a plant native to tropical Africa and intensively cultivated in Sudan. Its calyces are widely consumed with many uses in Sudanese folk medicine. The dried calyces of H. sabdariffa were subjected to soak in 80% v/v methanol to get the methanolic extract, which was tested against five Gram-negative and three Gram-positive referenced bacterial strains using disc diffusion method. Selected bioactive phytochemical compounds were also investigated using qualitative methods. The results of the antibacterial test indicate that the methanol extract of H. sabdariffa calyces contained effective antibacterial agent(s), revealed a considerable zone of inhibition against all tested Gram-negative and Gram-positive bacteria, and it was a competitor to gentamicin and greatly higher than penicillin which showed weak or no effect. The results of current investigation support the folk medicine application of this plant against different microbial ailments and suggest it as a promising source for new antibacterial agents.

Antibacterial efficiency of the Sudanese Roselle (Hibiscus sabdariffa L.), a famous beverage from Sudanese folk medicine

PubMed Central

Abdallah, Emad Mohamed

2016-01-01

Background: Hibiscus sabdariffa L. is a plant native to tropical Africa and intensively cultivated in Sudan. Its calyces are widely consumed with many uses in Sudanese folk medicine. Materials and Methods: The dried calyces of H. sabdariffa were subjected to soak in 80% v/v methanol to get the methanolic extract, which was tested against five Gram-negative and three Gram-positive referenced bacterial strains using disc diffusion method. Selected bioactive phytochemical compounds were also investigated using qualitative methods. Results: The results of the antibacterial test indicate that the methanol extract of H. sabdariffa calyces contained effective antibacterial agent(s), revealed a considerable zone of inhibition against all tested Gram-negative and Gram-positive bacteria, and it was a competitor to gentamicin and greatly higher than penicillin which showed weak or no effect. Conclusion: The results of current investigation support the folk medicine application of this plant against different microbial ailments and suggest it as a promising source for new antibacterial agents. PMID:27104041

Axinellamines as Broad-Spectrum Antibacterial Agents: Scalable Synthesis and Biology

PubMed Central

2015-01-01

Antibiotic-resistant bacteria present an ongoing challenge to both chemists and biologists as they seek novel compounds and modes of action to out-maneuver continually evolving resistance pathways, especially against Gram-negative strains. The dimeric pyrrole–imidazole alkaloids represent a unique marine natural product class with diverse primary biological activity and chemical architecture. This full account traces the strategy used to develop a second-generation route to key spirocycle 9, culminating in a practical synthesis of the axinellamines and enabling their discovery as broad-spectrum antibacterial agents, with promising activity against both Gram-positive and Gram-negative bacteria. While their detailed mode of antibacterial action remains unclear, the axinellamines appear to cause secondary membrane destabilization and impart an aberrant cellular morphology consistent with the inhibition of normal septum formation. This study serves as a rare example of a natural product initially reported to be devoid of biological activity surfacing as an active antibacterial agent with an intriguing mode of action. PMID:25328977

Anti-ageing effects of dentifrices containing anti-oxidative, anti-inflammatory, and anti-bacterial agents (Tomarina®) on gingival collagen degradation in rats.

PubMed

Koichiro, Irie; Tomofuji, Takaaki; Ekuni, Daisuke; Endo, Yasumasa; Kasuyama, Kenta; Azuma, Tetsuji; Tamaki, Naofumi; Yoneda, Toshiki; Morita, Manabu

2014-01-01

Previous studies have demonstrated the relationship between ageing and oxidative stress. In this study, we examined the effects of topical application of a dentifrice containing anti-oxidative, anti-inflammatory, and anti-bacterial agents (Tomarina®) to the gingival surface on gingival collagen degradation in rats. Fischer 344 male rats (4 or 8 months old) were divided into two groups: experimental group and control group. Tomarina® (the experimental group) or control dentifrice (the control group) was applied 5 days per week for 2 months. In the control group, gingival collagen density decreased with ageing. In the experimental group, the collagen density did not change with ageing, and was greater than that in the control group at 10 months of age (p < 0.0083). In addition, the control group showed an increase in serum oxidative stress with ageing. The experimental group also showed increased serum oxidative stress, but the value was lower than the control group at 10 months of age (p < 0.0083). Furthermore, low expressions of protein oxidative damage in the periodontal tissue were observed in the experimental group, compared to the control group at 6 months and 10 months. These findings indicate that Tomarina® might suppress the effects of ageing on gingival collagen degradation, by decreasing oxidative stress in the rat model.

Cost-effectiveness and pricing of antibacterial drugs.

PubMed

Verhoef, Talitha I; Morris, Stephen

2015-01-01

Growing resistance to antibacterial agents has increased the need for the development of new drugs to treat bacterial infections. Given increasing pressure on limited health budgets, it is important to study the cost-effectiveness of these drugs, as well as their safety and efficacy, to find out whether or not they provide value for money and should be reimbursed. In this article, we systematically reviewed 38 cost-effectiveness analyses of new antibacterial agents. Most studies showed the new antibacterial drugs were cost-effective compared to older generation drugs. Drug pricing is a complicated process, involving different stakeholders, and has a large influence on cost-effectiveness. Value-based pricing is a method to determine the price of a drug at which it can be cost-effective. It is currently unclear what the influence of value-based pricing will be on the prices of new antibacterial agents, but an important factor will be the definition of 'value', which as well as the impact of the drug on patient health might also include other factors such as wider social impact and the health impact of disease. © 2015 The Authors. Chemical Biology & Drug Design Published by John Wiley & Sons Ltd.

Bismuth subsalicylate nanoparticles with anaerobic antibacterial activity for dental applications

NASA Astrophysics Data System (ADS)

Vega-Jiménez, A. L.; Almaguer-Flores, A.; Flores-Castañeda, M.; Camps, E.; Uribe-Ramírez, M.; Aztatzi-Aguilar, O. G.; De Vizcaya-Ruiz, A.

2017-10-01

In recent years, nanomaterials have been used in the medical-dental field as new alternative antimicrobial agents. Bismuth subsalicylate (BSS) has been used as an antimicrobial agent, but the effect of BSS in the form of nanoparticles (BSS-nano) as a potential antimicrobial agent has not been tested, in specific against bacteria responsible for periodontal disease. The aim of this study was to evaluate the antibacterial effect of BSS-nano against oral anaerobic bacteria and to assess the safety of BSS-nano by evaluating their cytotoxicity in human gingival fibroblast (HGF-1) cells. BSS-nano were synthesized by laser ablation and were previously physico-chemically characterized using in vitro assays. The antibacterial activity was measured using the tetrazolium-based XTT assay, and cytotoxicity was determined using lactate dehydrogenase (LDH) and MTS assays in HGF-1 cells. Transmission electron microscopy of HGF-1 exposed to BSS-nano was also performed. BSS-nano was shown to have a primary size of 4-22 nm and a polygonal shape. Among the tested bacterial strains, those with a greater sensitivity to BSS-nano (highest concentration of 21.7 μg ml-1) were A. actinomycetemcomitans, C. gingivalis, and P. gingivalis. BSS-nano at a concentration of 60 μg ml-1 showed low cytotoxicity (6%) in HFG-1 cells and was mainly localized intracellularly in acidic vesicles. Our results indicate that the concentration of BSS-nano used as an effective antibacterial agent does not induce cytotoxicity in mammalian cells; thus, BSS-nano can be applied as an antibacterial agent in dental materials or antiseptic solutions.

Anticancer and antibacterial secondary metabolites from the endophytic fungus Penicillium sp. CAM64 against multi-drug resistant Gram-negative bacteria.

PubMed

Jouda, Jean-Bosco; Tamokou, Jean-de-Dieu; Mbazoa, Céline Djama; Sarkar, Prodipta; Bag, Prasanta Kumar; Wandji, Jean

2016-09-01

The emergence of multiple-drug resistance bacteria has become a major threat and thus calls for an urgent need to search for new effective and safe anti-bacterial agents. This study aims to evaluate the anticancer and antibacterial activities of secondary metabolites from Penicillium sp., an endophytic fungus associated with leaves of Garcinia nobilis. The culture filtrate from the fermentation of Penicillium sp. was extracted and analyzed by liquid chromatography-mass spectrometry, and the major metabolites were isolated and identified by spectroscopic analyses and by comparison with published data. The antibacterial activity of the compounds was assessed by broth microdilution method while the anticancer activity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The fractionation of the crude extract afforded penialidin A-C (1-3), citromycetin (4), p-hydroxyphenylglyoxalaldoxime (5) and brefelfin A (6). All of the compounds tested here showed antibacterial activity (MIC = 0.50 - 128 µg/mL) against Gramnegative multi-drug resistance bacteria, Vibrio cholerae (causative agent of dreadful disease cholera) and Shigella flexneri (causative agent of shigellosis), as well as the significant anticancer activity (LC 50 = 0.88 - 9.21 µg/mL) against HeLa cells. The results obtained indicate that compounds 1-6 showed good antibacterial and anticancer activities with no toxicity to human red blood cells and normal Vero cells.

Interaction of Silver Nanoparticles with Serum Proteins Affects Their Antimicrobial Activity In Vivo

PubMed Central

Gnanadhas, Divya Prakash; Ben Thomas, Midhun; Thomas, Rony; Raichur, Ashok M.

2013-01-01

The emergence of multidrug-resistant bacteria is a global threat for human society. There exist recorded data that silver was used as an antimicrobial agent by the ancient Greeks and Romans during the 8th century. Silver nanoparticles (AgNPs) are of potential interest because of their effective antibacterial and antiviral activities, with minimal cytotoxic effects on the cells. However, very few reports have shown the usage of AgNPs for antibacterial therapy in vivo. In this study, we deciphered the importance of the chosen methods for synthesis and capping of AgNPs for their improved activity in vivo. The interaction of AgNPs with serum albumin has a significant effect on their antibacterial activity. It was observed that uncapped AgNPs exhibited no antibacterial activity in the presence of serum proteins, due to the interaction with bovine serum albumin (BSA), which was confirmed by UV-Vis spectroscopy. However, capped AgNPs [with citrate or poly(vinylpyrrolidone)] exhibited antibacterial properties due to minimized interactions with serum proteins. The damage in the bacterial membrane was assessed by flow cytometry, which also showed that only capped AgNPs exhibited antibacterial properties, even in the presence of BSA. In order to understand the in vivo relevance of the antibacterial activities of different AgNPs, a murine salmonellosis model was used. It was conclusively proved that AgNPs capped with citrate or PVP exhibited significant antibacterial activities in vivo against Salmonella infection compared to uncapped AgNPs. These results clearly demonstrate the importance of capping agents and the synthesis method for AgNPs in their use as antimicrobial agents for therapeutic purposes. PMID:23877702

Antimicrobial properties of honey.

PubMed

Israili, Zafar H

2014-01-01

Honey has been widely accepted as food and medicine by all generations, traditions, and civilizations, both ancient and modern. For at least 2700 years, honey has been used by humans to treat a variety of ailments through topical application, but only recently have the antiseptic and antimicrobial properties of honey been discovered. Honey has been reported to be effective in a number of human pathologies. Clinical studies have demonstrated that application of honey to severely infected cutaneous wounds rapidly clears infection from the wound and improves tissue healing. A large number of in vitro and limited clinical studies have confirmed the broad-spectrum antimicrobial (antibacterial, antifungal, antiviral, and antimycobacterial) properties of honey, which may be attributed to the acidity (low pH), osmotic effect, high sugar concentration, presence of bacteriostatic and bactericidal factors (hydrogen peroxide, antioxidants, lysozyme, polyphenols, phenolic acids, flavonoids, methylglyoxal, and bee peptides), and increase in cytokine release, and to immune modulating and anti-inflammatory properties of honey; the antimicrobial action involves several mechanisms. Despite a large amount of data confirming the antimicrobial activity of honey, there are no studies that support the systemic use of honey as an antibacterial agent.

Atmospheric pressure plasma deposition of antimicrobial coatings on non-woven textiles

NASA Astrophysics Data System (ADS)

Nikiforov, Anton Yu.; Deng, Xiaolong; Onyshchenko, Iuliia; Vujosevic, Danijela; Vuksanovic, Vineta; Cvelbar, Uros; De Geyter, Nathalie; Morent, Rino; Leys, Christophe

2016-08-01

A simple method for preparation of nanoparticle incorporated non-woven fabric with high antibacterial efficiency has been proposed based on atmospheric pressure plasma process. In this work direct current plasma jet stabilized by fast nitrogen flow was used as a plasma deposition source. Three different types of the nanoparticles (silver, copper and zinc oxide nanoparticles) were employed as antimicrobial agents. X-ray photoelectron spectroscopy (XPS) measurements have shown a positive chemical shift observed for Ag 3d 5/2 (at 368.1 eV) suggests that silver nanoparticles (AgNPs) are partly oxidized during the deposition. The surface chemistry and the antibacterial activity of the samples against Staphylococcus aureus and Escherichia coli were investigated and analyzed. It is shown that the samples loaded with nanoparticles of Ag and Cu and having the barrier layer of 10 nm characterized by almost 97% of bacterial reduction whereas the samples with ZnO nanoparticles provide 86% reduction of Staphylococcus aureus. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

Topical anti-infective sinonasal irrigations: update and literature review.

PubMed

Lee, Jivianne T; Chiu, Alexander G

2014-01-01

Sinonasal anti-infective irrigations have emerged as a promising therapeutic modality in the comprehensive management of chronic rhinosinusitis (CRS), particularly in the context of recalcitrant disease. The purpose of this article was to delineate the current spectrum of topical anti-infective therapies available and evaluate their role in the treatment of CRS. A systematic literature review was performed on all studies investigating the use of topical antimicrobial solutions in the medical therapy of CRS. Anti-infective irrigations were stratified into topical antibacterial, antifungal, and additive preparations according to their composition and respective microbicidal properties. The use of topical antibiotic irrigations has been supported by low-level studies in the treatment of refractory CRS, with optimal results achieved in patients who have undergone prior functional endoscopic sinus surgery and received culture-directed therapy. Multiple evidence-based reviews have not established any clinical benefit with the administration of topical antifungals, and their use is not currently recommended in the management of routine CRS. Topical additives including surfactants may be beneficial as adjunctive treatment for recalcitrant CRS, but additional research is needed to investigate their efficacy in comparison with other agents and establish safety profiles. Topical anti-infective solutions are not recommended as first-line therapy for routine CRS but may be considered as a potential option for patients with refractory CRS who have failed traditional medical and surgical intervention. Additional research is necessary to determine which patient populations would derive the most benefit from each respective irrigation regimen and identify potential toxicities associated with prolonged use.

Small Peptides Derived from Penetratin as Antibacterial Agents.

PubMed

Parravicini, Oscar; Somlai, Csaba; Andujar, Sebastián A; Garro, Adriana D; Lima, Beatriz; Tapia, Alejandro; Feresin, Gabriela; Perczel, Andras; Tóth, Gabor; Cascales, Javier López; Rodríguez, Ana M; Enriz, Ricardo D

2016-04-01

The synthesis, in vitro evaluation and conformational study of several small-size peptides acting as antibacterial agents are reported. Among the compounds evaluated, the peptides Arg-Gln-Ile-Lys-Ile-Trp-Arg-Arg-Met-Lys-Trp-Lys-Lys-NH2 , Arg-Gln-Ile-Lys-Ile-Arg-Arg-Met-Lys-Trp-Arg-NH2 , and Arg-Gln-Ile-Trp-Trp-Trp-Trp-Gln-Arg-NH2 exhibited significant antibacterial activity. These were found to be very active antibacterial compounds, considering their small molecular size. In order to better understand the antibacterial activity obtained for these peptides, an exhaustive conformational analysis was performed, using both theoretical calculations and experimental measurements. Molecular dynamics simulations using two different media (water and trifluoroethanol/water) were employed. The results of these theoretical calculations were corroborated by experimental circular dichroism measurements. A brief discussion on the possible mechanism of action of these peptides at molecular level is also presented. Some of the peptides reported here constitute very interesting structures to be used as starting compounds for the design of new small-size peptides possessing antibacterial activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Cefazolin efficacy and antibiotic sensitivity against pathogenic bacteria in pediatric with acute upper urinary tract infection].

PubMed

Fuke, Toshiya; Abe, Yoshifusa; Hoshino, Akihiro; Oto, Hideyasu; Sakai, Naho; Murayama, Junichiro; Yoshida, Koichiro; Itabashi, Kazuo

2010-05-01

Acute upper urinary tract infection may cause sepsis, especially in neonates and infants, mandating the choice of appropriate, effective antibacterials minimizing increasing bacterial resistance. Frequently prescribing broad-spectrum cephalosporinin is one such example. Different antibacterial therapies are initiated clinically due to treatment protocol differences among institutions, disease severity, etc. We studied the efficacy of cefazolin (CEZ), a first-generation cephalosporin, as first-line parenteral treatment in acute upper urinary tract infection. We found that 88.9% of microbial infections have indications for CEZ. CEZ efficacy is 91.3%, and 97.2% of urine cultures show negative results. Escherichia coli sensitivity to antibacterial agents is 90.9% of the minimal inhibitory concentration (MIC) < 4 for CEZ, 93.9% of MIC < 1 for ceftazidime (CAZ), 63.6% of MIC < 4 for ampicillin, and 81.8% of MIC < 2 for gentamicin. CEZ thus has the same efficacy as CAZ and is more effective than other antibacterial agents against E. coli. We concluded that CEZ is an effective antibacterial in initial antibacterial pediatric therapy in acute upper urinary tract infection.

Preparing high-adhesion silver coating on APTMS modified polyethylene with excellent anti-bacterial performance

NASA Astrophysics Data System (ADS)

Li, Wenfei; Chen, Yunxiang; Wu, Song; Zhang, Jian; Wang, Hao; Zeng, Dawen; Xie, Changsheng

2018-04-01

Silver coating as a broad-spectrum antimicrobial agent was considered to alleviate the inflammation caused by intrauterine device (IUD) in endometrium. In this work, to avoid the damage of silver coating and ensure its antibacterial properties, 3-aminopropyltrimethoxysilane (APTMS) was introduced to modify the polyethylene (PE) substrate for the purpose of improving the adhesion of the silver coating. From the 90° peel test, it could be found that the adhesive strength of silver coating on the APTMS modified PE substrate was nearly 23 times stronger than the silver coating on substrate without surface modification. The dramatically enhanced adhesive strength could be attributed to the formation of continuous chemical bonds between the silver coatings and substrates after surface modification, which had been confirmed by the XPS. Moreover, the standard antibacterial test revealed that the silver coated samples against Staphylococcus aureus (S. aureus) exhibit excellent antibacterial efficacy. Considering the largely enhanced adhesion and the effective antibacterial property, it is reasonable to believe that the silver coating could be considered as a potential candidate for the antibacterial agent in IUD.

Hydrolysis of Synthetic Esters by the Antibacterial Agent in Serum

PubMed Central

Yotis, William W.

1966-01-01

Yotis, William W. (Loyola University, Chicago, Ill.). Hydrolysis of synthetic esters by the antibacterial agent in serum. J. Bacteriol. 91:488–493. 1966.—An antistaphylococcal serum agent was assayed colorimetrically, manometrically, and titrimetrically for esterase activity. p-Nitrophenol acetate, triacetin, l-lysine methyl and ethyl ester, and norleucine methyl ester were hydrolyzed by the antistaphylococcal agent. Acetylcholine and benzoylcholine esters, triolein, tristearin, and p-tosylarginine methyl ester were not attacked by this agent. With p-nitrophenol acetate as substrate, optimal activity occurred at pH 7.4. Incubation at 60 C for 30 min reduced drastically the esterase activity of the antistaphylococcal agent, and incubation at 75 C for 30 min abolished the esterase activity of this agent. Almost complete inhibition of esterase activity was observed with 0.001 m HgCl2, ZnSO4, and ethylenediaminetetraacetic acid (EDTA). EDTA inhibition could be reversed by the addition of CaCl2, but not MgCl2. Cysteine reversed the inhibition of HgCl2. NaF, atoxyl, diisopropyl fluorophosphate, quinine, and physostigmine did not influence the esterase activity of the antibacterial agent. The demonstration of esterase activity of both the antistaphylococcal agent and coagulase may shed further light on the reported ability of coagulase to neutralize the antistaphylococcal activity of this agent, or the prevention of absorption of the agent on the staphylococcal cell surface. In addition, the colorimetric procedure described in this report may be a convenient tool in assaying the potency of the antistaphylococcal agent. Images PMID:4956776

Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles

PubMed Central

Chen, Chen; Weir, Michael D.; Cheng, Lei; Lin, Nancy; Lin-Gibson, Sheng; Chow, Laurence C.; Zhou, Xuedong; Xu, Hockin H. K.

2015-01-01

Objectives Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Methods Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Results Adding 5% DMADDM and 10–40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p > 0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6–10 folds. Significance Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was “smart” and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent containing DMADDM and NACP may be promising to inhibit biofilms and remineralize tooth lesions thereby increasing the restoration longevity. PMID:24954647

Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles.

PubMed

Chen, Chen; Weir, Michael D; Cheng, Lei; Lin, Nancy J; Lin-Gibson, Sheng; Chow, Laurence C; Zhou, Xuedong; Xu, Hockin H K

2014-08-01

Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Adding 5% DMADDM and 10-40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p>0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6-10 folds. Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was "smart" and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent containing DMADDM and NACP may be promising to inhibit biofilms and remineralize tooth lesions thereby increasing the restoration longevity. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Chicken cathelicidin-2-derived peptides with enhanced immunomodulatory and antibacterial activities against biological warfare agents.

PubMed

Molhoek, E Margo; van Dijk, Albert; Veldhuizen, Edwin J A; Dijk-Knijnenburg, Helma; Mars-Groenendijk, Roos H; Boele, Linda C L; Kaman-van Zanten, Wendy E; Haagsman, Henk P; Bikker, Floris J

2010-09-01

Host defence peptides (HDPs) are considered to be excellent candidates for the development of novel therapeutic agents. Recently, it was demonstrated that the peptide C1-15, an N-terminal segment of chicken HDP cathelicidin-2, exhibits potent antibacterial activity while lacking cytotoxicity towards eukaryotic cells. In the present study, we report that C1-15 is active against bacteria such as Bacillus anthracis and Yersinia pestis that may potentially be used by bioterrorists. Substitution of single and multiple phenylalanine (Phe) residues to tryptophan (Trp) in C1-15 resulted in variants with improved antibacterial activity against B. anthracis and Y. pestis as well as decreased salt sensitivity. In addition, these peptides exhibited enhanced neutralisation of lipopolysaccharide (LPS)-induced release of pro-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs). The antibacterial and LPS-neutralising activities of these C1-15-derived peptides are exerted at concentrations far below the concentrations that are toxic to human PBMCs. Taken together, we show that Phe-->Trp substitutions in C1-15 variants enhances the antibacterial and LPS-neutralising activities against pathogenic bacteria, including those that may potentially be used as biological warfare agents. Copyright (c) 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Synthesis and potent in vitro activity of novel 1H-benzimidazoles as anti-MRSA agents.

PubMed

Karataş, Hacer; Alp, Mehmet; Yildiz, Sulhiye; Göker, Hakan

2012-08-01

A new class of 1H-benzimidazolecarboxamidines was synthesized and evaluated for in vitro antibacterial and antifungal activities, including drug-resistant bacterial strains. The most potent compound (32) has the same ratio of anti-MRSA activity as Vancomycin (minimal inhibitory concentrations value 0.78 μg/mL). The mechanism of action for 1H-benzimidazolecarboxamidine appears to be different from existing antibacterial agents. These compounds have potential for development as a new class of potent anti-MRSA agent. © 2012 John Wiley & Sons A/S.

Synthesis and biological evaluation of 2-arylimino-3-pyridin-thiazolineone derivatives as antibacterial agents.

PubMed

Cai, Ming-Guang; Wu, Yang; Chang, Jun

2016-05-15

With an intention to find more potent antibacterial agents, four halogen disubstituted thiazolineone derivatives (2a-d), five halogen monosubstituted thiazolineone derivatives (2e-i), and eleven 2-arylimino-3-pyridin-thiazolineone derivatives (2j-t) were synthesized and screened for their antibacterial activity, bactericidal activity, cytotoxicity, and erythrocyte hemolysis. Most of the synthesized derivatives showed antibacterial activity in inhibiting the growth of S. epidermidis and MRSA, and exhibited safety in the cytotoxicity study on the Vero cells and hemolytic activities test on healthy human erythrocytes. 2-Arylimino-3-pyridin-thiazolineone derivatives not only improved the clog P, but also showed potent antibacterial activity in inhibiting the growth of S. epidermidis and MRSA. In particularly, several compounds (2f, 2i, 2r and 2t) showed bactericidal activity, in which compound 2r displayed the best inhibitory capacity among the synthesized compounds, and further druggability research is on going. Copyright © 2016 Elsevier Ltd. All rights reserved.

A simple fragment of cyclic acyldepsipeptides is necessary and sufficient for ClpP activation and antibacterial activity.

PubMed

Carney, Daniel W; Compton, Corey L; Schmitz, Karl R; Stevens, Julia P; Sauer, Robert T; Sello, Jason K

2014-10-13

The development of new antibacterial agents, particularly those with unique biological targets, is essential to keep pace with the inevitable emergence of drug resistance in pathogenic bacteria. We identified the minimal structural component of the cyclic acyldepsipeptide (ADEP) antibiotics that exhibits antibacterial activity. We found that N-acyldifluorophenylalanine fragments function via the same mechanism of action as ADEPs, as evidenced by the requirement of ClpP for the fragments' antibacterial activity, the ability of fragments to activate Bacillus subtilis ClpP in vitro, and the capacity of an N-acyldifluorophenylalanine affinity matrix to capture ClpP from B. subtilis cell lysates. N-acyldifluorophenylalanine fragments are much simpler in structure than the full ADEPs and are also highly amenable to structural diversification. Thus, the stage has been set for the development of non-peptide activators of ClpP that can be used as antibacterial agents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Silver Nanoparticles Synthesized Using Caesalpinia sappan Extract as Potential Novel Nanoantibiotics Against Methicillin-Resistant Staphylococcus aureus.

PubMed

Jun, Sang Hui; Cha, Song-Hyun; Kim, Jae-Hyun; Yoon, Minho; Cho, Seonho; Park, Youmie

2015-08-01

Silver nanoparticles (AgNPs) have been shown to be effective antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA). In this study, AgNPs were synthesized using Caesalpinia sappan extract as a reducing agent to convert Ag+ to AgNPs. Seven stabilizers (surfactants and polymers) were added during the reduction step to increase the colloidal stability and to enhance the antibacterial activity of the AgNPs. Spherical and amorphous particles were primarily observed, with estimated diameters ranging from 30.2 to 47.5 nm. X-ray diffraction confirmed the face centered cubic structures of the AgNPs. Among the employed stabilizers, the cationic surfactant cetyltrimethylammonium bromide (CTAB) exhibited the highest antibacterial activity against 19 strains of MRSA, followed by polyvinylpyrrolidone (PVP, average molecular weight of 10,000). In contrast, the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (NaDDBS) did not exhibit any significant antibacterial activity, suggesting that the cationic surfactant head group contributed to the higher antibacterial activity of the AgNPs against MRSA.

Developpement d'un film antibacterien ayant des proprietes de glissement pour une meilleure processabilite

NASA Astrophysics Data System (ADS)

Silverwood, Richard

Product safety is of crucial importance for the food industry. The challenge of food safety is evidenced by the number of food poisoning in Canada and worldwide. An outbreak of listeriosis in 2008, having put the safety of Canadians at risk, has motivated the revision of the strategy for food safety in Canada. In this context, a collaboration between two major industrial players in Quebec and École Polytechnique de Montréal was initiated. This collaboration is supported by the creation of the Research Chair for safe, smart and sustainable food. One of the many forefront projects of this research chair is to develop a package having a bactericidal effect. Many compounds are currently available for incorporation into a finished product. Zinc Omadine™ by ArchChemicals and Irgaguard™ by BASF are some examples of products that have proven themselves. However, the incorporation of a bactericidal agent in a product having a direct contact with food must meet certain safety criteria. Thus, an overview of various antibacterial agents is made in terms of their effectiveness and their potential use in packaging a food product. To date, no technology allows easy incorporation of an antibacterial agent in a polymer matrix. Antibacterial constituents of the mixture with the polymer melt will provide the simplicity pursued. We chose nano zinc oxide as the main antibacterial agent for its mode of action, its great potential for sustainability and its ability not to migrate out of the polyethylene polymer matrix. Moreover, the effect of trace element at very low concentrations is validated. To increase efficiency, good dispersion is achieved by adding a polyethylene with maleic anhydride grafted groups. The increase in antibacterial properties by this change has been proven. Although these films exhibit a marked bactericidal effect, a lack of persistence of the antibacterial effect was noticed. This is probably due to a rearrangement of the molecular structure on the surface. This rearrangement, due to the polar nature of particles, inhibits the antibacterial effect of the particles, causing them to migrate to a critical distance, outside their scope. Furthermore, we evaluated briefly some other antibacterial agents. Calcium oxide (CaO) demonstrated, although lower than ZnO, an interesting antibacterial potential. The specificity of the bactericidal for gram-positive bacteria for this variance. The addition of iron oxide (Fe2O3) did not, by its hydrophilic properties, increase the bactericidal properties of CaO, simply by mixing them. Also, the use of thymol (component of essential oil of thyme) was effective, even at very low doses. A question mark hangs, however, the sustainability of such an agent. Its use in conjunction with a compatibilizer could result in a much more persistent bactericidal effect, slowing the process of migrating to the film surface. This effect is reduced when the bactericidal thymol is mixed with ZnO in the polyethylene matrix. Finally, a tool for optimizing slip additives was developed. To do this, a correlation that links the absorbance in infrared spectroscopy (ATR reflection) to the surface concentration of the lubricant was developed. By using this correlation, also called master curve, and an infrared spectrometer to test an unknown film, it is possible to find the initial concentration of slip additive. These studies highlight the potential use of zinc oxide and thymol as efficient bactericidal agent for the food industry. This work represents the first effort to develop an antibacterial film, involving nanoscale metal oxides and a polymer matrix of polyolefin.

The ATP-binding site of type II topoisomerases as a target for antibacterial drugs.

PubMed

Maxwell, Anthony; Lawson, David M

2003-01-01

DNA topoisomerases are essential enzymes in all cell types and have been found to be valuable drug targets both for antibacterial and anti-cancer chemotherapy. Type II topoisomerases possess a binding site for ATP, which can be exploited as a target for chemo-therapeutic agents. High-resolution structures of protein fragments containing this site complexed with antibiotics or an ATP analogue have provided vital information for the understanding of the action of existing drugs and for the potential development of novel anti-bacterial agents. In this article we have reviewed the structure and function of the ATPase domain of DNA gyrase (bacterial topoisomerase II), particularly highlighting novel information that has been revealed by structural studies. We discuss the efficacy and mode of action of existing drugs and consider the prospects for the development of novel agents.

Solvothermal synthesis of ZnO nanoparticles and anti-infection application in vivo.

PubMed

Bai, Xiangyang; Li, Linlin; Liu, Huiyu; Tan, Longfei; Liu, Tianlong; Meng, Xianwei

2015-01-21

Zinc oxide nanoparticles (ZnONPs) have been widely studied as the bacteriostatic reagents. However, synthesis of small ZnO nanoparticles with good monodispersion and stability in aqueous solution is still a challenge. Anti-infection research of ZnONPs used as antibacterial agent in vivo is rare. In this paper, a novel, sustainable, and simple method to synthesize ZnO nanoparticles with good monodispersion in aqueous low-temperature conditions and with a small molecule agent is reported. Inhibition zone test and the minimum inhibitory concentration test were performed to examine the antibacterial activity of ZnONPs against bacteria Staphylococcus aureus and Escherichia coli in vitro. For further application in vivo, low cytotoxicity and low acute toxicity in mice of ZnO were demonstrated. Finally, 4 nm ZnONPs combined with poly(vinyl alcohol) gel was used as antibacterial agent in rodent elytritis model, and significant anti-infection effect was proven. In one word, the present research would shed new light on the designing of antibacterial materials like ZnO with promising application in disinfection.

Current Technology in the Discovery and Development of Novel Antibacterials.

PubMed

Chung, Pooi Yin

2018-01-01

Bacterial resistance to antibiotics is one of the most serious challenge to global public health. The introduction of new antibiotics in clinical settings, i.e. agents that belong to a new class of antibacterials, act on new targets or has a novel mechanisms of action, may not be sufficient to cope with the emergence of multidrug-resistant pathogens such as Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii and Escherichia coli, which are increasingly prevalent in healthcare settings in Europe, the USA and Asia. Hence, coordinated efforts in minimizing the risk of spread of resistant bacteria and renewing research efforts in the search for novel antibacterial agents are urgently needed to manage this global crisis. This review highlights the challenges and potential in using current technologies in the discovery and development of novel antibacterial agents to keep up with the constantly evolving resistance in bacteria. With the explosion of bacterial genomic data and rapid development of new sequencing technologies, the understanding of bacterial pathogenesis and identification of novel antibiotic targets have significantly improved. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Design, synthesis and structure-activity relationship evaluation of novel LpxC inhibitors as Gram-negative antibacterial agents.

PubMed

Ding, Shi; Dai, Rui-Yang; Wang, Wen-Ke; Cao, Qiao; Lan, Le-Fu; Zhou, Xian-Li; Yang, Yu-She

2018-01-15

LpxC inhibitors are new-type antibacterial agents developed in the last twenty years, mainly against Gram-negative bacteria infections. To develop novel LpxC inhibitors with good antibacterial activities and biological metabolism, we summarized the basic skeleton of reported LpxC inhibitors, designed and synthesized several series of compounds and tested their antibacterial activities against Escherichial coli and Pseudomonas aeruginosa in vitro. Structure-activity relationships have been discussed in this article. The metabolism stability of YDL-2, YDL-5, YDL-8, YDL-14, YDL-20-YDL-23 have been evaluated in liver microsomes, which indicated that the 2-amino isopropyl group may be a preferred structure than the 2-hydroxy ethyl group in the design of LpxC inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and pharmacological evaluation of pyrazolo[4,3-c]cinnoline derivatives as potential anti-inflammatory and antibacterial agents.

PubMed

Tonk, Rajiv Kumar; Bawa, Sandhya; Chawla, Gita; Deora, Girdhar Singh; Kumar, Suresh; Rathore, Vandana; Mulakayala, Naveen; Rajaram, Azad; Kalle, Arunasree M; Afzal, Obaid

2012-11-01

A series of pyrazolo[4,3-c]cinnoline derivatives was synthesized, characterized and evaluated for anti-inflammatory and antibacterial activity. Test compounds that exhibited good anti-inflammatory activity were further screened for their ulcerogenic and lipid peroxidation activity. Compounds 4d and 4l showed promising anti-inflammatory activity with reduced ulcerogenic and lipid peroxidation activity when compared to naproxen. Docking results of these two compounds with COX-2 (PDB ID: 1CX2) also exhibited a strong binding profile. Among the test derivatives, compound 4i displayed significant antibacterial property against gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus) bacteria. However, compound 4b emerged as the best dual anti-inflammatory-antibacterial agent in the present study. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

[The combination effects of antibacterial agents against clinical isolated multiple-drug resistant Pseudomonas aeruginosa].

PubMed

Maesaki, Shigefumi; Yamaguchi, Toshiyuki; Sasaki, Kazumasa; Hashikita, Giichi; Shibuya, Shunsuke; Watanabe, Masaharu; Takayama, Sadao; Kawakami, Sayoko; Nagasawa, Mitsuaki; Suzuki, Noriyasu; Uchida, Takashi; Okabe, Tadashi; Kobayashi, Sugako

2006-02-01

The effectiveness of antibacterial agents against 70 strains of clinically isolated multiple-drug resistant Pseudomonas aeruginosa (MDRP) was measured by the micro dilution method. Fifty of all strains (71%) produced metallo-beta-lactamase and the IMP-1 gene was detected by polymerase chain reaction (PCR). The MIC90 (the minimum inhibitory concentration of an antibiotic necessary to inhibit the growth of 90% of bacterial strains) values of biapenem (BIPM), meropenem (MEPM), tazobactam/piperacillin (TAZ/PIPC), sulbactam/ cefoperazone (SBT/CPZ), cefepime (CFPM), ciprofloxacin (CPFX), pazufloxacin (PZFX), amikacin (AMK) and aztreonam (AZT) were found to be 265, 512, 256, 512, 512, 64, 128, 128 and 128 microg/mL, respectively. The in vitro combination effects of antibacterial agents were examined against 62 strains of MDRP and the synergy or additive effects were evaluated by fractional inhibitory concentration (FIC) index calculated by the checkerboard method. The combination of AMK and AZT showed synergy effects on 15/59 (25.4%) strains of MDRP. The synergy and additive effects on the MDRP strains were also found by the other antibacterial agents combination such as TAZ/PIPC and AMK, CFPM and AMK, and SBT/CPZ and AZT. These results suggested the necessity of further investigation of clinical usefulness.

Time for a change: addressing R&D and commercialization challenges for antibacterials

PubMed Central

Payne, David J.; Miller, Linda Federici; Findlay, David; Anderson, James; Marks, Lynn

2015-01-01

The antibacterial therapeutic area has been described as the perfect storm. Resistance is increasing to the point that our hospitals encounter patients infected with untreatable pathogens, the overall industry pipeline is described as dry and most multinational pharmaceutical companies have withdrawn from the area. Major contributing factors to the declining antibacterial industry pipeline include scientific challenges, clinical/regulatory hurdles and low return on investment. This paper examines these challenges and proposes approaches to address them. There is a need for a broader scientific agenda to explore new approaches to discover and develop antibacterial agents. Additionally, ideas of how industry and academia could be better integrated will be presented. While promising progress in the regulatory environment has been made, more streamlined regulatory paths are still required and the solutions will lie in global harmonization and clearly defined guidance. Creating the right incentives for antibacterial research and development is critical and a new commercial model for antibacterial agents will be proposed. One key solution to help resolve both the problem of antimicrobial resistance (AMR) and lack of new drug development are rapid, cost-effective, accurate point of care diagnostics that will transform antibacterial prescribing and enable more cost-effective and efficient antibacterial clinical trials. The challenges of AMR are too great for any one group to resolve and success will require leadership and partnerships among academia, industry and governments globally. PMID:25918443

Synthesis and Antibacterial Evaluation of Novel 3-Substituted Ocotillol-Type Derivatives as Leads.

PubMed

Bi, Yi; Liu, Xian-Xuan; Zhang, Heng-Yuan; Yang, Xiao; Liu, Ze-Yun; Lu, Jing; Lewis, Peter John; Wang, Chong-Zhi; Xu, Jin-Yi; Meng, Qing-Guo; Ma, Cong; Yuan, Chun-Su

2017-04-07

Due to the rapidly growing bacterial antibiotic-resistance and the scarcity of novel agents in development, bacterial infection is still a global problem. Therefore, new types of antibacterial agents, which are effective both alone and in combination with traditional antibiotics, are urgently needed. In this paper, a series of antibacterial ocotillol-type C-24 epimers modified from natural 20( S )-protopanaxadiol were synthesized and evaluated for their antibacterial activity. According to the screening results of Gram-positive bacteria ( B. subtilis 168 and MRSA USA300) and Gram-negative bacteria ( P. aer PAO1 and A. baum ATCC19606) in vitro, the derivatives exhibited good antibacterial activity, particularly against Gram-positive bacteria with an minimum inhibitory concentrations (MIC) value of 2-16 µg/mL. The subsequent synergistic antibacterial assay showed that derivatives 5c and 6c enhanced the susceptibility of B. subtilis 168 and MRSA USA300 to chloramphenicol (CHL) and kanamycin (KAN) (FICI < 0.5). Our data showed that ocotillol-type derivatives with long-chain amino acid substituents at C-3 were good leads against antibiotic-resistant pathogens MRSA USA300, which could improve the ability of KAN and CHL to exhibit antibacterial activity at much lower concentrations with reduced toxicity.

Characterization and interplay of bacteriocin and exopolysaccharide-mediated silver nanoparticles as an antibacterial agent.

PubMed

Ansari, Asma; Pervez, Sidra; Javed, Urooj; Abro, Muhammad Ishaque; Nawaz, Muhammad Asif; Qader, Shah Ali Ul; Aman, Afsheen

2018-04-22

Metallic nanoparticles have a substantial scientific interest because of their distinctive physicochemical and antimicrobial properties and the emergence of multidrug resistant pathogens could unlock the potential of nanoparticles to combat infectious diseases. The aim of the current study is to enhance the antibacterial potential of purified bacteriocin by combining bacteriocin and antibacterial silver nanoparticles (AgNPs). Hence, the interaction of natural antimicrobial compounds and antibacterial nanoparticles can be used as a potential tool for combating infectious diseases. In this study, a green, simple and effective approach is used to synthesize antibacterial AgNPs using fungal exopolysaccharide as both a reducing and stabilizing agent. The AgNPs were characterized by spectroscopic analysis, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Dynamic Light Scattering (DLS). Furthermore, the synergistic effect of bacteriocin-AgNPs was determined against pathogenic strains. The histogram of AgNPs indicated well-dispersed, stabilized and negatively charged particles with variable size distribution. The combination of bacteriocin with nanoparticles found to be more effective due to broad antibacterial potential with possibly lower doses. The current study is imperative to provide an alternative for the chemical synthesis of silver nanoparticles. It showed environmental friendly and cost effective green synthesis of antibacterial nanoparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

Surface modification of polypropylene mesh devices with cyclodextrin via cold plasma for hernia repair: Characterization and antibacterial properties

NASA Astrophysics Data System (ADS)

Sanbhal, Noor; Mao, Ying; Sun, Gang; Xu, Rui Fang; Zhang, Qian; Wang, Lu

2018-05-01

Light weight polypropylene (PP) mesh is the most widely used implant among all other synthetic meshes for hernia repair. However, infection is the complication associated to all synthetic meshes after hernia repair. Thus, to manage mesh related infection; antibacterial drug is generally loaded to surgical implants to supply drug locally in mesh implanted site. Nevertheless, PP mesh restricts the loading of antibacterial drug at operated area due to its low wettability. The aim of this study was to introduce a novel antimicrobial PP mesh modified with β-cyclodextrine (CD) and loaded with antimicrobial agent for infection prevention. A cold oxygen plasma treatment was able to activate the surfaces of polypropylene fibers, and then CD was incorporated onto the surfaces of PP fibers. Afterward, triclosan, as a model antibacterial agent, was loaded into CD cavity to provide desired antibacterial functions. The modified polypropylene mesh samples CD-Tric-1, CD-Tric-3 exhibited excellent inhibition zone and continuous antibacterial efficacy against E. coli and S. aureus up to 6 and 7 days respectively. Results of AFM, SEM, FTIR and antibacterial tests evidenced that oxygen plasma process is necessary to increase chemical connection between CD molecules and PP fibers. The samples were also characterized by using EDX, XRD, TGA, DSC and water contact angle.

Effects of dual antibacterial agents MDPB and nano-silver in primer on microcosm biofilm, cytotoxicity and dentin bond properties

PubMed Central

Zhang, Ke; Cheng, Lei; Imazato, Satoshi; Antonucci, Joseph M.; Lin, Nancy J.; Lin-Gibson, Sheng; Bai, Yuxing; Xu, Hockin H. K.

2013-01-01

Objectives The objective of this study was to investigate the effects of dentin primer containing dual antibacterial agents, namely, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and nanoparticles of silver (NAg), on dentin bond strength, dental plaque microcosm biofilm response, and fibroblast cytotoxicity for the first time. Methods Scotchbond Multi-Purpose (SBMP) was used as the parent bonding agent. Four primers were tested: SBMP primer control (referred to as “P”), P+5%MDPB, P+0.05%NAg, and P+5%MDPB+0.05%NAg. Dentin shear bond strengths were measured using extracted human teeth. Biofilms from the mixed saliva of 10 donors were cultured to investigate metabolic activity, colony-forming units (CFU), and lactic acid production. Human fibroblast cytotoxicity of the four primers was tested in vitro. Results Incorporating MDPB and NAg into primer did not reduce dentin bond strength compared to control (p>0.1). SEM revealed well-bonded adhesive-dentin interfaces with numerous resin tags. MDPB or NAg each greatly reduced biofilm viability and acid production, compared to control. Dual agents MDPB+NAg had a much stronger effect than either agent alone (p<0.05), increasing inhibition zone size and reducing metabolic activity, CFU and lactic acid by an order of magnitude, compared to control. There was no difference in cytotoxicity between commercial control and antibacterial primers (p>0.1). Conclusions The method of using dual agents MDPB+NAg in the primer yielded potent antibacterial properties. Hence, this method may be promising to combat residual bacteria in tooth cavity and invading bacteria at the margins. The dual agents MDPB+NAg may have wide applicability to other adhesives, composites, sealants and cements to inhibit biofilms and caries. PMID:23402889

[Determination of in vitro susceptibilities of Brucella spp. strains against 11 different antibacterial gents isolated from blood cultures].

PubMed

Keşli, Recep; Bilgin, Hüseyin; Yılmaz, Halim

2017-07-01

Brucellosis is a worldwide zoonotic disease and still continuous to be a major public health problem. In this study, it was aimed to identify the Brucella strains to the species level isolated from blood cultures, and to determine the rate of antimicrobial susceptibility against eleven antibacterial agents. A total of 106 Brucella spp. strains were included in the study, which were isolated from blood cultures in University of Health Sciences, Konya Training and Research Hospital, Medical Microbiology Laboratory between January 2011 and June 2013. Identification of the isolated strains were mainly based on conventional methods. In vitro antibacterial susceptibilities of azithromycin, ciprofloxacin, doxycycline, gentamicin, levofloxacin, moxifloxacin, rifampicin, streptomycin, tetracycline, tigecycline, and trimethoprim/sulfamethoxazole, were evaluated by using the gradient (E-test, bioMerieux, France) strip method. The bacterial suspensions adjusted to 0.5 McFarland turbidity was inoculated to Mueller Hinton agar plates, supplemented with 5% sheep blood, and E-test strips of selected antibacterial were applied. The plates were incubated in ambient air 48 hours at 37ºC and Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213 were used as quality control strains for antimicrobial susceptibility testing. Minimum inhibitors concentration (MIC) values were interpreted according to Clinical and Laboratory Standards Institute (CLSI) guidelines for slow-growing bacteria such as Haemophilus spp. Of the 106 Brucella spp. strains included in to the study, 90 were identified as Brucella melitensis, and 16 were Brucella abortus. MIC90 values of azithromycin, ciprofloxacin, doxycycline, gentamicin, levofloxacin, moxifloxacin, rifampicin, streptomycin, tetracycline, tigecycline, and trimethoprim/sulfamethoxazole were determined as 1 µg/ml, 0.25 µg/ml, 0.19 µg/ml, 0.25 µg/ml, 0.19 µg/ml, 0.75 µg/ml, 0.25 µg/ml, 0.75 µg/ml, 0.38 µg/ml, 0.64 µg/ml, and 0.19 µg/ml respectively. According to MIC90 values, gentamicin, moxifloxacin, and trimethoprim/sulfamethoxazole, were the most effective antibacterial agents. All the Brucella strains were sensitive to all the tested antibacterial agents except rifampicin. Only six isolates showed intermediate susceptibility to rifampicin. With regard to fluoroquinolones, the most active antibacterial agent was moxifloxacin, followed by ciprofloxacin and levofloxacin. In our study, no resistance was found for the classically recommended antibacterial agents used in the treatment of Brucella species in our hospital but antibiotic susceptibility patterns of Brucella spp. may vary geographically. As a result it was concluded that, the antimicrobial susceptibilities of Brucella species should be determined and controlled periodically to avoid the possible development of resistance problems in the future.

Methyl-hydroxylamine as an efficacious antibacterial agent that targets the ribonucleotide reductase enzyme.

PubMed

Julián, Esther; Baelo, Aida; Gavaldà, Joan; Torrents, Eduard

2015-01-01

The emergence of multidrug-resistant bacteria has encouraged vigorous efforts to develop antimicrobial agents with new mechanisms of action. Ribonucleotide reductase (RNR) is a key enzyme in DNA replication that acts by converting ribonucleotides into the corresponding deoxyribonucleotides, which are the building blocks of DNA replication and repair. RNR has been extensively studied as an ideal target for DNA inhibition, and several drugs that are already available on the market are used for anticancer and antiviral activity. However, the high toxicity of these current drugs to eukaryotic cells does not permit their use as antibacterial agents. Here, we present a radical scavenger compound that inhibited bacterial RNR, and the compound's activity as an antibacterial agent together with its toxicity in eukaryotic cells were evaluated. First, the efficacy of N-methyl-hydroxylamine (M-HA) in inhibiting the growth of different Gram-positive and Gram-negative bacteria was demonstrated, and no effect on eukaryotic cells was observed. M-HA showed remarkable efficacy against Mycobacterium bovis BCG and Pseudomonas aeruginosa. Thus, given the M-HA activity against these two bacteria, our results showed that M-HA has intracellular antimycobacterial activity against BCG-infected macrophages, and it is efficacious in partially disassembling and inhibiting the further formation of P. aeruginosa biofilms. Furthermore, M-HA and ciprofloxacin showed a synergistic effect that caused a massive reduction in a P. aeruginosa biofilm. Overall, our results suggest the vast potential of M-HA as an antibacterial agent, which acts by specifically targeting a bacterial RNR enzyme.

Antibacterial and Antifungal Activities of Spices

PubMed Central

Liu, Qing; Meng, Xiao; Li, Ya; Zhao, Cai-Ning; Tang, Guo-Yi; Li, Hua-Bin

2017-01-01

Infectious diseases caused by pathogens and food poisoning caused by spoilage microorganisms are threatening human health all over the world. The efficacies of some antimicrobial agents, which are currently used to extend shelf-life and increase the safety of food products in food industry and to inhibit disease-causing microorganisms in medicine, have been weakened by microbial resistance. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Many spices—such as clove, oregano, thyme, cinnamon, and cumin—possessed significant antibacterial and antifungal activities against food spoilage bacteria like Bacillus subtilis and Pseudomonas fluorescens, pathogens like Staphylococcus aureus and Vibrio parahaemolyticus, harmful fungi like Aspergillus flavus, even antibiotic resistant microorganisms such as methicillin resistant Staphylococcus aureus. Therefore, spices have a great potential to be developed as new and safe antimicrobial agents. This review summarizes scientific studies on the antibacterial and antifungal activities of several spices and their derivatives. PMID:28621716

Antibacterial and Antifungal Activities of Spices.

PubMed

Liu, Qing; Meng, Xiao; Li, Ya; Zhao, Cai-Ning; Tang, Guo-Yi; Li, Hua-Bin

2017-06-16

Infectious diseases caused by pathogens and food poisoning caused by spoilage microorganisms are threatening human health all over the world. The efficacies of some antimicrobial agents, which are currently used to extend shelf-life and increase the safety of food products in food industry and to inhibit disease-causing microorganisms in medicine, have been weakened by microbial resistance. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Many spices-such as clove, oregano, thyme, cinnamon, and cumin-possessed significant antibacterial and antifungal activities against food spoilage bacteria like Bacillus subtilis and Pseudomonas fluorescens , pathogens like Staphylococcus aureus and Vibrio parahaemolyticus, harmful fungi like Aspergillus flavus, even antibiotic resistant microorganisms such as methicillin resistant Staphylococcus aureus. Therefore, spices have a great potential to be developed as new and safe antimicrobial agents. This review summarizes scientific studies on the antibacterial and antifungal activities of several spices and their derivatives.

The effect of eugenol on the cariogenic properties of Streptococcus mutans and dental caries development in rats

PubMed Central

XU, JING-SHU; LI, YAO; CAO, XUE; CUI, YUN

2013-01-01

Eugenol has been widely used in medicine due to its antibacterial, anti-inflammatory, antioxidant, anticancer and analgesic properties. The present study was designed to investigate the effects of eugenol on the cariogenic properties of Streptococcus mutans and dental caries development in rats. Eugenol demonstrated significant inhibitory effects against acid production by S. mutans. The synthesis of water-insoluble glucans by glucosyltransferases was reduced by eugenol. Eugenol also markedly suppressed the adherence of S. mutans to saliva-coated hydroxyapatite beads. Furthermore, topical application of eugenol reduced the incidence and severity of carious lesions in rats. These results suggest that the natural compound eugenol may be a useful therapeutic agent for dental caries. PMID:23837051

Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity.

PubMed

Kaviya, S; Santhanalakshmi, J; Viswanathan, B; Muthumary, J; Srinivasan, K

2011-08-01

Biosynthesis of silver nanoparticles (AgNPs) was achieved by a novel, simple green chemistry procedure using citrus sinensis peel extract as a reducing and a capping agent. The effect of temperature on the synthesis of silver nanoparticles was carried out at room temperature (25°C) and 60°C. The successful formation of silver nanoparticles has been confirmed by UV-vis, FTIR, XRD, EDAX, FESEM and TEM analysis and their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa (gram-negative), and Staphylococcus aureus (gram-positive) has been studied. The results suggest that the synthesized AgNPs act as an effective antibacterial agent. Copyright © 2011 Elsevier B.V. All rights reserved.

Cobalt Complexes as Antiviral and Antibacterial Agents

DTIC Science & Technology

2010-01-01

observed. Complex 26 has antibacterial activity against E. coli, S. aureus and Micrococcus lysodeikiticus, showing better growth inhibitory activity in...complexes exhibited activity towards E. coli, B. subtilis, S. aureus and Micrococcus lysodeikiticus. Figure 15. Selenium containing and

Antibacterial household products: cause for concern.

PubMed Central

Levy, S. B.

2001-01-01

The recent entry of products containing antibacterial agents into healthy households has escalated from a few dozen products in the mid-1990s to more than 700 today. Antibacterial products were developed and have been successfully used to prevent transmission of disease-causing microorganisms among patients, particularly in hospitals. They are now being added to products used in healthy households, even though an added health benefit has not been demonstrated. Scientists are concerned that the antibacterial agents will select bacteria resistant to them and cross-resistant to antibiotics. Moreover, if they alter a person's microflora, they may negatively affect the normal maturation of the T helper cell response of the immune system to commensal flora antigens; this change could lead to a greater chance of allergies in children. As with antibiotics, prudent use of these products is urged. Their designated purpose is to protect vulnerable patients. PMID:11485643

Antibacterial household products: cause for concern.

PubMed

Levy, S B

2001-01-01

The recent entry of products containing antibacterial agents into healthy households has escalated from a few dozen products in the mid-1990s to more than 700 today. Antibacterial products were developed and have been successfully used to prevent transmission of disease-causing microorganisms among patients, particularly in hospitals. They are now being added to products used in healthy households, even though an added health benefit has not been demonstrated. Scientists are concerned that the antibacterial agents will select bacteria resistant to them and cross-resistant to antibiotics. Moreover, if they alter a person's microflora, they may negatively affect the normal maturation of the T helper cell response of the immune system to commensal flora antigens; this change could lead to a greater chance of allergies in children. As with antibiotics, prudent use of these products is urged. Their designated purpose is to protect vulnerable patients.

Antioxidant, antibacterial and anti-aging activities of intracellular zinc polysaccharides from Grifola frondosa SH-05.

PubMed

Zhang, Chen; Gao, Zheng; Hu, Chunlong; Zhang, Jianjun; Sun, Xinyi; Rong, Chengbo; Jia, Le

2017-02-01

In present work, the strain of Grifola frondosa SH-05 was used as a vector of zinc biotransformation to produce the IZPS. The bioactivities including antioxidant and antibacterial activities in vitro and anti-aging properties in vivo of IZPS were investigated comparing with the IPS. The results which were in consistent with the results of histopathology assay demonstrated that the IZPS had superior antioxidant and anti-aging activities by scavenging the hydroxyl and DPPH radicals, increasing enzyme activities, decreasing the MDA contents and ameliorating the anile condition of mice. Besides, the IZPS also showed potential antibacterial activities. The IZPS with higher bioactivities was composed of were Rha, Ino and Glu with a molar ratio of 4.7:3.6:1. These conclusions indicated that the IZPS might be a potential source of natural antioxidant, antibacterial agent and anti-aging agent. Copyright © 2016 Elsevier B.V. All rights reserved.

Combating resistance: application of the emerging science of pharmacokinetics and pharmacodynamics.

PubMed

Jacobs, Michael R

2007-12-01

During the last 10-15 years understanding of relationships between pharmacokinetic (PK) and pharmacodynamic (PD) parameters and bacteriological and clinical outcomes has expanded allowing correlation between in vitro potency and in vivo efficacy. PK and PD principles can be applied to development of new antibacterials and formulation of existing agents to help address the increasing prevalence of antibacterial resistance. For beta-lactams, such as penicillins, the unbound serum concentration of the drug exceeding the minimum inhibitory concentration of the causative pathogen for 40-50% of the dosing interval is predictive of bacteriologic efficacy (bacterial eradication) and can be used to determine a PK/PD breakpoint for that specific dosing regimen. Amoxicillin/clavulanate was one of the earliest antibacterials to use the unique approach of PK/PD principles to develop new and enhanced formulations, allowing it to remain a significant antibacterial agent in the management of respiratory tract infections.

Synthesis and structure-activity relationship of amidine derivatives of 3,4-ethylenedioxythiophene as novel antibacterial agents.

PubMed

Stolić, Ivana; Čipčić Paljetak, Hana; Perić, Mihaela; Matijašić, Mario; Stepanić, Višnja; Verbanac, Donatella; Bajić, Miroslav

2015-01-27

Current antibacterial chemotherapeutics are facing an alarming increase in bacterial resistance pressuring the search for novel agents that would expand the available therapeutic arsenal against resistant bacterial pathogens. In line with these efforts, a series of 9 amidine derivatives of 3,4-ethylenedioxythiophene were synthesized and, together with 18 previously synthesized analogs, evaluated for their relative DNA binding affinity, in vitro antibacterial activities and preliminary in vitro safety profile. Encouraging antibacterial activity of several subclasses of tested amidine derivatives against Gram-positive (including resistant MRSA, MRSE, VRE strains) and Gram-negative bacterial strains was observed. The bis-phenyl derivatives were the most antibacterially active, while compound 19 from bis-benzimidazole class exhibited the widest spectrum of activity (with MIC of 4, 2, 0.5 and ≤0.25 μg/ml against laboratory strains of Staphyloccocus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Moraxella catarrhalis, respectively and 4-32 μg/ml against clinical isolates of sensitive and resistant S. aureus, Staphylococcus epidermidis and Enterococcus faecium) and also demonstrated the strongest DNA binding affinity (ΔTm of 15.4 °C). Asymmetrically designed compounds and carboxamide-amidines were, in general, less active. Molecular docking indicated that the shape of the 3,4-ethylenedioxythiophene derivatives and their ability to form multiple electrostatic and hydrogen bonds with DNA, corresponds to the binding modes of other minor-groove binders. Herein reported results encourage further investigation of this class of compounds as novel antibacterial DNA binding agents. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Tricyclic GyrB/ParE (TriBE) Inhibitors: A New Class of Broad-Spectrum Dual-Targeting Antibacterial Agents

PubMed Central

Tari, Leslie W.; Li, Xiaoming; Trzoss, Michael; Bensen, Daniel C.; Chen, Zhiyong; Lam, Thanh; Zhang, Junhu; Lee, Suk Joong; Hough, Grayson; Phillipson, Doug; Akers-Rodriguez, Suzanne; Cunningham, Mark L.; Kwan, Bryan P.; Nelson, Kirk J.; Castellano, Amanda; Locke, Jeff B.; Brown-Driver, Vickie; Murphy, Timothy M.; Ong, Voon S.; Pillar, Chris M.; Shinabarger, Dean L.; Nix, Jay; Lightstone, Felice C.; Wong, Sergio E.; Nguyen, Toan B.; Shaw, Karen J.; Finn, John

2013-01-01

Increasing resistance to every major class of antibiotics and a dearth of novel classes of antibacterial agents in development pipelines has created a dwindling reservoir of treatment options for serious bacterial infections. The bacterial type IIA topoisomerases, DNA gyrase and topoisomerase IV, are validated antibacterial drug targets with multiple prospective drug binding sites, including the catalytic site targeted by the fluoroquinolone antibiotics. However, growing resistance to fluoroquinolones, frequently mediated by mutations in the drug-binding site, is increasingly limiting the utility of this antibiotic class, prompting the search for other inhibitor classes that target different sites on the topoisomerase complexes. The highly conserved ATP-binding subunits of DNA gyrase (GyrB) and topoisomerase IV (ParE) have long been recognized as excellent candidates for the development of dual-targeting antibacterial agents with broad-spectrum potential. However, to date, no natural product or small molecule inhibitors targeting these sites have succeeded in the clinic, and no inhibitors of these enzymes have yet been reported with broad-spectrum antibacterial activity encompassing the majority of Gram-negative pathogens. Using structure-based drug design (SBDD), we have created a novel dual-targeting pyrimidoindole inhibitor series with exquisite potency against GyrB and ParE enzymes from a broad range of clinically important pathogens. Inhibitors from this series demonstrate potent, broad-spectrum antibacterial activity against Gram-positive and Gram-negative pathogens of clinical importance, including fluoroquinolone resistant and multidrug resistant strains. Lead compounds have been discovered with clinical potential; they are well tolerated in animals, and efficacious in Gram-negative infection models. PMID:24386374

Time for a change: addressing R&D and commercialization challenges for antibacterials.

PubMed

Payne, David J; Miller, Linda Federici; Findlay, David; Anderson, James; Marks, Lynn

2015-06-05

The antibacterial therapeutic area has been described as the perfect storm. Resistance is increasing to the point that our hospitals encounter patients infected with untreatable pathogens, the overall industry pipeline is described as dry and most multinational pharmaceutical companies have withdrawn from the area. Major contributing factors to the declining antibacterial industry pipeline include scientific challenges, clinical/regulatory hurdles and low return on investment. This paper examines these challenges and proposes approaches to address them. There is a need for a broader scientific agenda to explore new approaches to discover and develop antibacterial agents. Additionally, ideas of how industry and academia could be better integrated will be presented. While promising progress in the regulatory environment has been made, more streamlined regulatory paths are still required and the solutions will lie in global harmonization and clearly defined guidance. Creating the right incentives for antibacterial research and development is critical and a new commercial model for antibacterial agents will be proposed. One key solution to help resolve both the problem of antimicrobial resistance (AMR) and lack of new drug development are rapid, cost-effective, accurate point of care diagnostics that will transform antibacterial prescribing and enable more cost-effective and efficient antibacterial clinical trials. The challenges of AMR are too great for any one group to resolve and success will require leadership and partnerships among academia, industry and governments globally. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Quaternary ammonium salts substituted by 5-phenyl-1,3,4-oxadiazole-2-thiol as novel antibacterial agents with low cytotoxicity.

PubMed

Wang, Chun-Hua; Xie, Xian-Rui; Liu, Wen-Shuai; Hou, Gui-Ge; Sun, Ju-Feng; Zhao, Feng; Cong, Wei; Li, Hong-Juan; Xin, Wen-Yu

2017-11-01

Twenty-one novel 5-phenyl-1,3,4-oxadiazole-2-thiol (POT) substituted N-hydroxyethyl quaternary ammonium salts (6a-g, 7a-g, 8a-g) were prepared and characterized by FTIR, NMR, and elemental analysis. Compounds 6a, 6c, and 8a were confirmed by X-ray single-crystal diffraction. They display the unsurpassed antibacterial activity against Staphylococcus aureus, α-H-tococcus, Escherichia coli, P. aeruginosa, Proteus vulgaris, Canidia Albicans, especially 6g, 7g, 8g with dodecyl group. Compounds 8a-d with N,N-dihydroxyethyl and POT groups display unsurpassed antibacterial activity and non-toxicity. The structure-activity relationships indicate that POT and flexible dihydroxyethyl group in QAS are necessary for antibacterial activity and cytotoxicity. SEM and TEM images of E. coli morphologies of 8d show the antibacterial agents can adhere to membrane surfaces to inhibit bacterial growth by disrupting peptidoglycan formation and releasing bacterial cytoplasm from cell membranes. © 2017 John Wiley & Sons A/S.

Antibacterial resistance in sub-Saharan Africa: an underestimated emergency

PubMed Central

Kariuki, Samuel; Dougan, Gordon

2014-01-01

Antibacterial resistance–associated infections are known to increase morbidity and mortality and cost of treatment and to potentially put others in the community at higher risk of infections. In high-income countries, where the burden of infectious diseases is relatively modest, resistance to first-line antibacterial agents is usually overcome by use of second- and third-line agents. However, in developing countries where the burden of infectious diseases is high, patients with antibacterial-resistant infections may be unable to obtain or afford effective second-line treatments. In sub-Saharan Africa (SSA), the situation is aggravated by poor hygiene, unreliable water supplies, civil conflicts, and increasing numbers of immunocompromised people, such as those with HIV, which facilitate both the evolution of resistant pathogens and their rapid spread in the community. Due to limited capacity for disease detection and surveillance, the burden of illnesses due to treatable bacterial infections, their specific etiologies, and the awareness of antibacterial resistance is less well established in most of SSA, and therefore the ability to mitigate their consequences is significantly limited. PMID:24628272

Virtual Screening Approach of Bacterial Peptide Deformylase Inhibitors Results in New Antibiotics.

PubMed

Merzoug, Amina; Chikhi, Abdelouahab; Bensegueni, Abderrahmane; Boucherit, Hanane; Okay, Sezer

2018-03-01

The increasing resistance of bacteria to antibacterial therapy poses an enormous health problem, it renders the development of new antibacterial agents with novel mechanism of action an urgent need. Peptide deformylase, a metalloenzyme which catalytically removes N-formyl group from N-terminal methionine of newly synthesized polypeptides, is an important target in antibacterial drug discovery. In this study, we report the structure-based virtual screening of ZINC database in order to discover potential hits as bacterial peptide deformylase enzyme inhibitors with more affinity as compared to GSK1322322, previously known inhibitor. After virtual screening, fifteen compounds of the top hits predicted were purchased and evaluated in vitro for their antibacterial activities against one Gram positive (Staphylococcus aureus) and three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella. pneumoniae) bacteria in different concentrations by disc diffusion method. Out of these, three compounds, ZINC00039650, ZINC03872971 and ZINC00126407, exhibited significant zone of inhibition. The results obtained were confirmed using the dilution method. Thus, these proposed compounds may aid the development of more efficient antibacterial agents. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Screening for Antibacterial and Antioxidant Activities and Phytochemical Analysis of Oroxylum indicum Fruit Extracts.

PubMed

Sithisarn, Patchima; Nantateerapong, Petcharat; Rojsanga, Piyanuch; Sithisarn, Pongtip

2016-04-07

Oroxylum indicum, which is called Pheka in Thai, is a traditional Thai plant in the Bignoniaceae family with various ethnomedical uses such as as an astringent, an anti-inflammatory agent, an anti-bronchitic agent, an anti-helminthic agent and an anti-microbial agent. The young fruits of this plant have also been consumed as vegetables. However, there has been no report concerning its antibacterial activities, especially activities related to clinically isolated pathogenic bacteria and the in vitro antioxidant effects of this plant. Therefore, the extracts from O. indicum fruits and seeds collected from different provinces in Thailand were prepared by decoction and maceration with ethanol and determined for their in vitro antibacterial effects on two clinically isolated bacteria, Streptococcus suis and Staphylococcus intermedius, using disc diffusion assay. Ethanol extracts from O. indicum fruits collected from Nakorn Pathom province at the concentration of 1000 mg/mL exhibited intermediate antibacterial activity against S. intermedius with an inhibition zone of 15.11 mm. Moreover, it promoted moderate inhibitory effects on S. suis with an inhibition zone of 14.39 mm. The extracts prepared by maceration with ethanol promoted higher antibacterial activities than those prepared with water. The ethanol extract from the seeds of this plant, purchased in Bangkok, showed stronger in vitro antioxidant activities than the other extracts, with an EC50 value of 26.33 µg/mL. Phytochemical analysis suggested that the seed ethanol extract contained the highest total phenolic and flavonoid contents (10.66 g% gallic acid equivalent and 7.16 g% quercetin equivalent, respectively) by a significant amount. Thin layer chromatographic analysis of the extracts showed the chromatographic band that could correspond to a flavonoid baicalein. From the results, extracts from O. indicum fruits have an in vitro antioxidant effect, with antibacterial potential, on clinically pathologic bacteria and they contain an antioxidant flavonoid which could be developed for medicinal and pharmaceutical purposes in the future.

Enabling virtual screening of potent and safer antimicrobial agents against noma: mtk-QSBER model for simultaneous prediction of antibacterial activities and ADMET properties.

PubMed

Speck-Planche, Alejandro; Cordeiro, M N D S

2015-01-01

Neglected diseases are infections that thrive mainly among underdeveloped countries, particularly those belonging to regions found in Asia, Africa, and America. One of the most complex diseases is noma, a dangerous health condition characterized by a polymicrobial and opportunistic nature. The search for potent and safer antibacterial agents against this disease is therefore a goal of particular interest. Chemoinformatics can be used to rationalize the discovery of drug candidates, diminishing time and financial resources. However, in the case of noma, there is no in silico model available for its use in the discovery of efficacious antibacterial agents. This work is devoted to report the first mtk-QSBER model, which integrates dissimilar kinds of chemical and biological data. The model was generated with the aim of simultaneously predicting activity against bacteria present in noma, and ADMET (absorption, distribution, metabolism, elimination, toxicity) parameters. The mtk-QSBER model was constructed by employing a large and heterogeneous dataset of chemicals and displayed accuracies higher than 90% in both training and prediction sets. We confirmed the practical applicability of the model by predicting multiple profiles of the investigational antibacterial drug delafloxacin, and the predictions converged with the experimental reports. To date, this is the first model focused on the virtual search for desirable anti-noma agents.

Facile Synthesis of Efficient Antibacterial Agent as CoFe₂O₄/Ag Composite Material Against Both Gram-Negative Escherichia coli and Gram-Positive Bacillus subtilis Bacteria.

PubMed

Gankhuyag, Sukhbayar; Lee, Kyoung; Bae, Dong Sik

2018-09-01

We have suggested that a facile synthesis of CoFe2O4/Ag composite material as an antibacterial agent for substitution of a chlorination agent for microbial infected wastewater treatment. The CoFe2O4/Ag was synthesized by an impregnation method in assistance with trisodium citrate as a reducing agent. The as-prepared uncalcined CoFe2O4 (CFG), calcined CoFe2O4 (CFG600), and calcined CoFe2O4/Ag (CFG600/Ag) composites were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray (EDX) techniques. Antibacterial activities were also determined in liquid culture by measuring the minimum inhibitory concentrations (MIC) against Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) bacteria in vitro. Results showed that CFG600/Ag composites had an excellent antibacterial activity in comparison with CFG and CFG600 composites. The CFG600/Ag composites have completely inhibited the growth of both E. coli and B. subtilis bacteria from concentrations of more than 0.25 mg/ml. Furthermore, the FE-SEM study demonstrated the physical damage of bacteria when treated with CFG600/Ag composite material at a concentration of 0.10 mg/ml.

Interference of Antibacterial Agents with Phagocyte Functions: Immunomodulation or “Immuno-Fairy Tales”?

PubMed Central

Labro, Marie-Thérése

2000-01-01

Professional phagocytes (polymorphonuclear neutrophils and monocytes/macrophages) are a main component of the immune system. These cells are involved in both host defenses and various pathological settings characterized by excessive inflammation. Accordingly, they are key targets for immunomodulatory drugs, among which antibacterial agents are promising candidates. The basic and historical concepts of immunomodulation will first be briefly reviewed. Phagocyte complexity will then be unravelled (at least in terms of what we know about the origin, subsets, ambivalent roles, functional capacities, and transductional pathways of this cell and how to explore them). The core subject of this review will be the many possible interactions between antibacterial agents and phagocytes, classified according to demonstrated or potential clinical relevance (e.g., neutropenia, intracellular accumulation, and modulation of bacterial virulence). A detailed review of direct in vitro effects will be provided for the various antibacterial drug families, followed by a discussion of the clinical relevance of these effects in two particular settings: immune deficiency and inflammatory diseases. The prophylactic and therapeutic use of immunomodulatory antibiotics will be considered before conclusions are drawn about the emerging (optimistic) vision of future therapeutic prospects to deal with largely unknown new diseases and new pathogens by using new agents, new techniques, and a better understanding of the phagocyte in particular and the immune system in general. PMID:11023961

Potential Mechanism of Action of 3'-Demethoxy-6-O-demethyl-isoguaiacin on Methicillin Resistant Staphylococcus aureus.

PubMed

Favela-Hernández, Juan Manuel J; Clemente-Soto, Aldo F; Balderas-Rentería, Isaías; Garza-González, Elvira; Camacho-Corona, María del Rayo

2015-07-08

Bacterial infections represent one of the main threats to global public health. One of the major causative agents associated with high morbidity and mortality infections in hospitals worldwide is methicillin-resistant Staphylococcus aureus. Therefore, there is a need to develop new antibacterial agents to treat these infections, and natural products are a rich source of them. In previous studies, we reported that lignan 3'-demethoxy-6-O-demethylisoguaiacin, isolated and characterized from Larrea tridentate, showed the best activity towards methicillin-resistant S. aureus. Thus, the aim of this study was to determine the potential molecular mechanism of the antibacterial activity of 3'-demethoxy-6-O-demethylisoguaiacin against methicillin-resistant S. aureus using microarray technology. Results of microarray genome expression were validated by real-time polymerase chain reaction (RT-PCR). The genetic profile expression results showed that lignan 3'-demethoxy-6-O-demethylisoguaiacin had activity on cell membrane affecting proteins of the ATP-binding cassette (ABC) transport system causing bacteria death. This molecular mechanism is not present in any antibacterial commercial drug and could be a new target for the development of novel antibacterial agents.

Potential mechanism of action of 3'-demethoxy-6-O-demethyl-isoguaiacin on methicillin resistant Staphylococcus aureus.

PubMed

Favela-Hernández, Juan Manuel J; Clemente-Soto, Aldo F; Balderas-Rentería, Isaías; Garza-González, Elvira; Camacho-Corona, María Del Rayo

2015-07-08

Bacterial infections represent one of the main threats to global public health. One of the major causative agents associated with high morbidity and mortality infections in hospitals worldwide is methicillin-resistant Staphylococcus aureus. Therefore, there is a need to develop new antibacterial agents to treat these infections, and natural products are a rich source of them. In previous studies, we reported that lignan 3'-demethoxy-6-O-demethylisoguaiacin, isolated and characterized from Larrea tridentate, showed the best activity towards methicillin-resistant S. aureus. Thus, the aim of this study was to determine the potential molecular mechanism of the antibacterial activity of 3'-demethoxy-6-O-demethylisoguaiacin against methicillin-resistant S. aureus using microarray technology. Results of microarray genome expression were validated by real-time polymerase chain reaction (RT-PCR). The genetic profile expression results showed that lignan 3'-demethoxy-6-O-demethylisoguaiacin had activity on cell membrane affecting proteins of the ATP-binding cassette (ABC) transport system causing bacteria death. This molecular mechanism is not present in any antibacterial commercial drug and could be a new target for the development of novel antibacterial agents.

Antibacterial and synergy of berberines with antibacterial agents against clinical multi-drug resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Zuo, Guo-Ying; Li, Yang; Han, Jun; Wang, Gen-Chun; Zhang, Yun-Ling; Bian, Zhong-Qi

2012-08-29

Antibacterial activity of berberine (Ber) and 8-acetonyl-dihydroberberine (A-Ber) alone and combined uses with antibacterial agents ampicillin (AMP), azithromycin (AZM), cefazolin (CFZ) and levofloxacin (LEV) was studied on 10 clinical isolates of SCCmec III type methicillin-resistant Staphylococcus aureus (MRSA). Susceptibility to each agent alone was tested using a broth microdilution method and the chequerboard and time-kill tests for the combined evaluations, respectively. The alone MICs/MBCs (μg/mL) ranges were 32-128/64-256 (Ber) and 32-128/128-512 (A-Ber). Significant synergies were observed for the Ber (A-Ber)/AZM and Ber (A-Ber)/LEV combinations against 90% of the tested MRSA strains, with fractional inhibitory concentration indices (FICIs) values ranged from 0.188 to 0.500. An additivity result was also observed for the Ber/AZM combination by time-kill curves. These results demonstrated for the first time that Ber and A-Ber enhanced the in vitro inhibitory efficacy of AZM and LEV to a same extent, which had potential for further investigation in combinatory therapeutic applications of patients infected with MRSA.

Characterization of plasma treated surfaces for food safety by terahertz spectroscopy

NASA Astrophysics Data System (ADS)

Sulovská, Kateřina; Lehocký, Marián.

2014-10-01

A physico-chemical approach to modify surfaces not only for use in medicine, but also for preservation of food is nowadays widely studied to lower the risks of increased number of bacterial pathogens that are in a direct contact with people. Food safety is very important part of preserving sustainability during crises, especially after the enterohaemorrhagic Escherichia coli outbreak in Europe in 2011. One of the possibility how we can protect food against various pathogens is the modification of packing materials that are directly in contact with preserved food. This contribution deals with the characterization of modified surfaces with antibacterial properties via Terahertz spectroscopy. For the purpose of this paper, three monomers were used for grafting onto air radiofrequency plasma activated low density polyethylene surface, which created a brush-like structure. Next, the antibacterial agents, Irgasan and Chlorhexidine, were anchored to these surfaces. These antibacterial agents were selected for supposed effect on two most frequently occurring bacterial strains - Escherichia coli and Staphylococcus aureus. Materials were further tested for the presence of antibacterial agent molecules, in our case by means of terahertz spectroscopy. Each material was tested on two spectroscopes - the SPECTRA and the OSCAT terahertz instruments.

In Vitro Studies on a Microfluidic Sensor with Embedded Obstacles Using New Antibacterial Synthetic Compounds (1-TDPPO) Mixed Prop-2-en-1-one with Difluoro Phenyl.

PubMed

Roh, Changhyun; Lee, Jaewoong; Kinger, Mayank; Kang, Chankyu

2017-04-08

This paper describes the use of an analytical microfluidic sensor for accelerating chemo-repellent response and strong anti-bacterial 1-(Thien-2-yl)-3-(2, 6-difluoro phenyl) prop-2-en-1-one (1-TDPPO). The chemically-synthesized antimicrobial agent, which included prop-2-en-1-one and difluoro phenyl groups, was moving through an optically transparent polydimethylsiloxane (PDMS) microfluidic sensor with circular obstacles arranged evenly. The response, growth and distribution of fluorescent labeling Pseudomonas aeruginosa PAO1 against the antimicrobial agent were monitored by confocal laser scanning microscope (CLSM). The microfluidic sensor along with 1-TDPPOin this study exhibits the following advantages: (i) Real-time chemo-repellent responses of cell dynamics; (ii) Rapid eradication of biofilm by embedded obstacles and powerful antibacterial agents, which significantly reduce the response time compared to classical methods; (iii) Minimal consumption of cells and antimicrobial agents; and (iv) Simplifying the process of the normalization of the fluorescence intensity and monitoring of biofilm by captured images and datasets.

Highly efficient treatment of aerobic vaginitis with simple acidic buffered gels: The importance of pH and buffers on the microenvironment of vaginas.

PubMed

Sun, Xiaodong; Qiu, Haiying; Jin, Yiguang

2017-06-15

Aerobic vaginitis (AV) leads to uterus deep infection or preterm birth. Antibacterial agents are not optimal therapeutics of AV. Here, we report a series of temperature-sensitive in situ forming acidic buffered gels for topical treatment of AV, involving lactate, acetate, and citrate gels at pH 3.5, 5.0, and 6.5. AV rat models were prepared following vaginal infection with Staphylococcus aureus and Escherichia coli. In vitro/in vivo studies of the buffered gels were performed compared with ofloxacin gels and blank gels. All the buffered gels showed the lower in vitro antibacterial activities than ofloxacin gels but the better in vivo anti-S. aureus effects and similar anti-E. coli effects. The buffered gels improved Lactobacillus growth in the vaginas. Both the healthy rat vaginal pH and the pH of rat vaginas treated with the buffered gels were about 6.5 though the AV rat models or ones treated with ofloxacin gels still remained at the high pH more than 7.0. After treatments with the buffered gels, the vaginal smears changed to a clean state nearly without aerobic bacteria, the vaginal tissues were refreshed, and the immunoreactions were downregulated. The acidic buffered gels bring rapid decrease of local vaginal pH, high antibacterial activities, improvement of probiotics, and alleviation of inflammation. They are simple, highly efficient, and safe anti-AV formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Public funding for research on antibacterial resistance in the JPIAMR countries, the European Commission, and related European Union agencies: a systematic observational analysis

PubMed Central

Kelly, Ruth; Zoubiane, Ghada; Walsh, Desmond; Ward, Rebecca; Goossens, Herman

2016-01-01

Summary Background Antibacterial resistant infections are rising continuously, resulting in increased morbidity and mortality worldwide. With no new antibiotic classes entering the market and the possibility of returning to the pre-antibiotic era, the Joint Programming Initiative on Antimicrobial Resistance (JPIAMR) was established to address this problem. We aimed to quantify the scale and scope of publicly funded antibacterial resistance research across JPIAMR countries and at the European Union (EU) level to identify gaps and future opportunities. Methods We did a systematic observational analysis examining antibacterial resistance research funding. Databases of funding organisations across 19 countries and at EU level were systematically searched for publicly funded antibacterial resistance research from Jan 1, 2007, to Dec 31, 2013. We categorised studies on the basis of the JPIAMR strategic research agenda's six priority topics (therapeutics, diagnostics, surveillance, transmission, environment, and interventions) and did an observational analysis. Only research funded by public funding bodies was collected and no private organisations were contacted for their investments. Projects in basic, applied, and clinical research, including epidemiological, public health, and veterinary research and trials were identified using keyword searches by organisations, and inclusion criteria were based on the JPIAMR strategic research agenda's six priority topics, using project titles and abstracts as filters. Findings We identified 1243 antibacterial resistance research projects, with a total public investment of €1·3 billion across 19 countries and at EU level, including public investment in the Innovative Medicines Initiative. Of the total amount invested in antibacterial resistance research across the time period, €646·6 million (49·5%) was invested at the national level and €659·2 million (50·5%) at the EU level. When projects were classified under the six priority topics we found that 763 (63%) of 1208 projects funded at national level were within the area of therapeutics, versus 185 (15%) in transmission, 131 (11%) in diagnostics, 53 (4%) in interventions, and only 37 (3%) in environment and 39 (3%) in surveillance. Interpretation This was the first systematic analysis of research funding of antibacterial resistance of this scale and scope, which relied on the availability and accuracy of data from organisations included. Large variation was seen between countries both in terms of number of projects and associated investment and across the six priority topics. To determine the future direction of JPIAMR countries a clear picture of the funding landscape across Europe and Canada is needed. Countries should work together to increase the effect of research funding by strengthening national and international coordination and collaborations, harmonising research activities, and collectively pooling resources to fund multidisciplinary projects. The JPIAMR have developed a publicly available database to document the antibacterial resistance research collected and can be used as a baseline to analyse funding from 2014 onwards. Funding JPIAMR and the European Commission. PMID:26708524

Synthesis and antibacterial evaluation of calcinated Ag-doped nano-hydroxyapatite with dispersibility.

PubMed

Furuzono, Tsutomu; Motaharul, Mazumder; Kogai, Yasumichi; Azuma, Yoshinao; Sawa, Yoshiki

2015-05-01

Dispersible hydroxyapatite (HAp) nanoparticles are very useful for applying a monolayer to implantable medical devices using the nano-coating technique. To improve tolerance to infection on implanted medical devices, silver-doped HAp (Ag-HAp) nanoparticles with dispersiblity and crystallinity were synthesized, avoiding calcination-induced sintering, and evaluated for antibacterial activity. The Ca10-xAgx(PO4)6(OH)2 with x = 0 and 0.2 were prepared by wet chemical processing at 100°C. Before calcination at 700°C for 2 h, two kinds of anti-sintering agents, namely a Ca(NO3)2 (Ca salt) and a polyacrylic acid/Ca salt mixture (PAA-Ca), were used. Escherichia coli was used to evaluate the antibacterial activity of the nanopowder. When PAA-Ca was used as an anti-sintering agent in calcination to prepare the dispersible nanoparticles, strong metallic Ag peaks were observed at 38.1° and 44.3° (2θ) in the X-ray diffraction (XRD) profile. However, the Ag peak was barely observed when Ca salt was used alone as the anti-sintering agent. Thus, using Ca salt alone was more effective for preparation of dispersible Ag-HAp than PAA-Ca. The particle average size of Ag-HAp with 0.5 mol% of Ag content was found to be 325 ± 70 nm when the formation of large particleaggregations was prevented, as determined by dynamic light scattering instrument. The antibacterial activity of the Ag-HAp nanoparticles possessing 0.5 mol% against E. coli was greater than 90.0%. Dispersible and crystalline nano Ag-HAp can be obtained by using Ca salt alone as an anti-sintering agent. The nanoparticles showed antibacterial activity.

Methyl-Hydroxylamine as an Efficacious Antibacterial Agent That Targets the Ribonucleotide Reductase Enzyme

PubMed Central

Julián, Esther; Baelo, Aida; Gavaldà, Joan; Torrents, Eduard

2015-01-01

The emergence of multidrug-resistant bacteria has encouraged vigorous efforts to develop antimicrobial agents with new mechanisms of action. Ribonucleotide reductase (RNR) is a key enzyme in DNA replication that acts by converting ribonucleotides into the corresponding deoxyribonucleotides, which are the building blocks of DNA replication and repair. RNR has been extensively studied as an ideal target for DNA inhibition, and several drugs that are already available on the market are used for anticancer and antiviral activity. However, the high toxicity of these current drugs to eukaryotic cells does not permit their use as antibacterial agents. Here, we present a radical scavenger compound that inhibited bacterial RNR, and the compound's activity as an antibacterial agent together with its toxicity in eukaryotic cells were evaluated. First, the efficacy of N-methyl-hydroxylamine (M-HA) in inhibiting the growth of different Gram-positive and Gram-negative bacteria was demonstrated, and no effect on eukaryotic cells was observed. M-HA showed remarkable efficacy against Mycobacterium bovis BCG and Pseudomonas aeruginosa. Thus, given the M-HA activity against these two bacteria, our results showed that M-HA has intracellular antimycobacterial activity against BCG-infected macrophages, and it is efficacious in partially disassembling and inhibiting the further formation of P. aeruginosa biofilms. Furthermore, M-HA and ciprofloxacin showed a synergistic effect that caused a massive reduction in a P. aeruginosa biofilm. Overall, our results suggest the vast potential of M-HA as an antibacterial agent, which acts by specifically targeting a bacterial RNR enzyme. PMID:25782003

Side Chain Degradable Cationic-Amphiphilic Polymers with Tunable Hydrophobicity Show in Vivo Activity.

PubMed

Uppu, Divakara S S M; Samaddar, Sandip; Hoque, Jiaul; Konai, Mohini M; Krishnamoorthy, Paramanandham; Shome, Bibek R; Haldar, Jayanta

2016-09-12

Cationic-amphiphilic antibacterial polymers with optimal amphiphilicity generally target the bacterial membranes instead of mammalian membranes. To date, this balance has been achieved by varying the cationic charge or side chain hydrophobicity in a variety of cationic-amphiphilic polymers. Optimal hydrophobicity of cationic-amphiphilic polymers has been considered as the governing factor for potent antibacterial activity yet minimal mammalian cell toxicity. However, the concomitant role of hydrogen bonding and hydrophobicity with constant cationic charge in the interactions of antibacterial polymers with bacterial membranes is not understood. Also, degradable polymers that result in nontoxic degradation byproducts offer promise as safe antibacterial agents. Here we show that amide- and ester (degradable)-bearing cationic-amphiphilic polymers with tunable side chain hydrophobicity can modulate antibacterial activity and cytotoxicity. Our results suggest that an amide polymer can be a potent antibacterial agent with lower hydrophobicity whereas the corresponding ester polymer needs a relatively higher hydrophobicity to be as effective as its amide counterpart. Our studies reveal that at higher hydrophobicities both amide and ester polymers have similar profiles of membrane-active antibacterial activity and mammalian cell toxicity. On the contrary, at lower hydrophobicities, amide and ester polymers are less cytotoxic, but the former have potent antibacterial and membrane activity compared to the latter. Incorporation of amide and ester moieties made these polymers side chain degradable, with amide polymers being more stable than the ester polymers. Further, the polymers are less toxic, and their degradation byproducts are nontoxic to mice. More importantly, the optimized amide polymer reduces the bacterial burden of burn wound infections in mice models. Our design introduces a new strategy of interplay between the hydrophobic and hydrogen bonding interactions keeping constant cationic charge density for developing potent membrane-active antibacterial polymers with minimal toxicity to mammalian cells.

Tricyclic GyrB/ParE (TriBE) Inhibitors. A new class of broad-spectrum dual-targeting antibacterial agents

DOE PAGES

Tari, Leslie W.; Li, Xiaoming; Trzoss, Michael; ...

2013-12-26

Increasing resistance to every major class of antibiotics and a dearth of novel classes of antibacterial agents in development pipelines has created a dwindling reservoir of treatment options for serious bacterial infections. The bacterial type IIA topoisomerases, DNA gyrase and topoisomerase IV, are validated antibacterial drug targets with multiple prospective drug binding sites, including the catalytic site targeted by the fluoroquinolone antibiotics. Growing resistance to fluoroquinolones, frequently mediated by mutations in the drug-binding site, is increasingly limiting the utility of this antibiotic class, prompting the search for other inhibitor classes that target different sites on the topoisomerase complexes. The highlymore » conserved ATP-binding subunits of DNA gyrase (GyrB) and topoisomerase IV (ParE) have long been recognized as excellent candidates for the development of dual-targeting antibacterial agents with broad-spectrum potential. However, to date, no natural product or small molecule inhibitors targeting these sites have succeeded in the clinic, and no inhibitors of these enzymes have yet been reported with broad-spectrum antibacterial activity encompassing the majority of Gram-negative pathogens. Using structure-based drug design (SBDD), we have created a novel dual-targeting pyrimidoindole inhibitor series with exquisite potency against GyrB and ParE enzymes from a broad range of clinically important pathogens. Inhibitors from this series demonstrate potent, broad-spectrum antibacterial activity against Gram-positive and Gram-negative pathogens of clinical importance, including fluoroquinolone resistant and multidrug resistant strains. Moreover, lead compounds have been discovered with clinical potential; they are well tolerated in animals, and efficacious in Gram-negative infection models.« less

Tricyclic GyrB/ParE (TriBE) Inhibitors. A new class of broad-spectrum dual-targeting antibacterial agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tari, Leslie W.; Li, Xiaoming; Trzoss, Michael

Increasing resistance to every major class of antibiotics and a dearth of novel classes of antibacterial agents in development pipelines has created a dwindling reservoir of treatment options for serious bacterial infections. The bacterial type IIA topoisomerases, DNA gyrase and topoisomerase IV, are validated antibacterial drug targets with multiple prospective drug binding sites, including the catalytic site targeted by the fluoroquinolone antibiotics. Growing resistance to fluoroquinolones, frequently mediated by mutations in the drug-binding site, is increasingly limiting the utility of this antibiotic class, prompting the search for other inhibitor classes that target different sites on the topoisomerase complexes. The highlymore » conserved ATP-binding subunits of DNA gyrase (GyrB) and topoisomerase IV (ParE) have long been recognized as excellent candidates for the development of dual-targeting antibacterial agents with broad-spectrum potential. However, to date, no natural product or small molecule inhibitors targeting these sites have succeeded in the clinic, and no inhibitors of these enzymes have yet been reported with broad-spectrum antibacterial activity encompassing the majority of Gram-negative pathogens. Using structure-based drug design (SBDD), we have created a novel dual-targeting pyrimidoindole inhibitor series with exquisite potency against GyrB and ParE enzymes from a broad range of clinically important pathogens. Inhibitors from this series demonstrate potent, broad-spectrum antibacterial activity against Gram-positive and Gram-negative pathogens of clinical importance, including fluoroquinolone resistant and multidrug resistant strains. Moreover, lead compounds have been discovered with clinical potential; they are well tolerated in animals, and efficacious in Gram-negative infection models.« less

Mur Ligase Inhibitors as Anti-bacterials: A Comprehensive Review.

PubMed

Sangshetti, Jaiprakash N; Joshi, Suyog S; Patil, Rajendra H; Moloney, Mark G; Shinde, Devanand B

2017-01-01

Exploring a new target for antibacterial drug discovery has gained much attention because of the emergence of Multidrug Resistance (MDR) strains of bacteria. To overcome this problem the development of novel antibacterial was considered as highest priority task and was one of the biggest challenge since multiple factors were involved. The bacterial peptidoglycan biosynthetic pathway has been well documented in the last few years and has been found to be imperative source for the development of novel antibacterial agents with high target specificity as they are essential for bacterial survival and have no homologs in humans. We have therefore reviewed the process of peptidoglycan biosynthesis which involves various steps like formation of UDP-Nacetylglucosamine (GlcNAc), UDP-N-acetylmuramic acid (MurNAc) and lipid intermediates (Lipid I and Lipid II) which are controlled by various enzymes like GlmS, GlmM, GlmU enzyme, followed by Mur Ligases (MurAMurF) and finally by MraY and MurG respectively. These four amide ligases MurC-MurF can be used as the source for the development of novel multi-target antibacterial agents as they shared and conserved amino acid regions, catalytic mechanisms and structural features. This review begins with the need for novel antibacterial agents and challenges in their development even after the development of bacterial genomic studies. An overview of the peptidoglycan monomer formation, as a source of disparity in this process is presented, followed by detailed discussion of structural and functional aspects of all Mur enzymes and different chemical classes of their inhibitors along with their SAR studies and inhibitory potential. This review finally emphasizes on different patents and novel Mur inhibitors in the development phase. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Synthesis, construction, and evaluation of self-assembled nano-bacitracin A as an efficient antibacterial agent in vitro and in vivo

PubMed Central

Hong, Wei; Gao, Xiang; Qiu, Peng; Yang, Jie; Qiao, Mingxi; Shi, Hong; Zhang, Dexian; Tian, Chunlian; Niu, Shengli; Liu, Mingchun

2017-01-01

Bacitracin A (BA) is an excellent polypeptide antibiotic that is active against gram-positive bacteria without triggering multidrug resistance. However, BA is inactive against gram-negative bacteria because of its inability to cross the outer membrane of these cells, and it has strong nephrotoxicity, thus limiting its clinical applications. Nanoantibiotics can effectively localize antibiotics to the periplasmic space of bacteria while decreasing the adverse effects of antibiotics. In this study, biodegradable hydrophobic copolymers of poly (d,l-lactide-co-glycolide) (PLGA) were attached to the N-termini of BA to design a novel class of self-assembled nano-bacitracin A (nano-BAs), and their potential as antibacterial agents was evaluated in vitro and in vivo. Nano-BAs had a core-shell structure with a mean diameter <150 nm. Impressively, nano-BAs had strong antibacterial properties against both gram-positive and gram-negative bacteria, and the distribution of antibacterial activity as a function of PLGA block length was skewed toward longer PLGA chains. No cytotoxicity against HK-2 cells or human red blood cells (hRBCs) was observed in vitro, suggesting good biocompatibility. A high local density of BA mass on the surface promoted endocytotic cellular uptake, and hydrophobic interactions between the PLGA block and lipopolysaccharide (LPS) facilitated the uptake of nano-BAs, thereby leading to greater antibacterial activities. In addition, Nano-BA5K was found to be effective in vivo, and it served as an anti-infective agent for wound healing. Collectively, this study provides a cost-effective means of developing self-assembling nano-polypeptide antibiotic candidates with a broader antibacterial spectrum and a lower toxicity than commercially available peptide antibiotics, owing to their modification with biodegradable copolymers. PMID:28721045

Synthesis, construction, and evaluation of self-assembled nano-bacitracin A as an efficient antibacterial agent in vitro and in vivo.

PubMed

Hong, Wei; Gao, Xiang; Qiu, Peng; Yang, Jie; Qiao, Mingxi; Shi, Hong; Zhang, Dexian; Tian, Chunlian; Niu, Shengli; Liu, Mingchun

2017-01-01

Bacitracin A (BA) is an excellent polypeptide antibiotic that is active against gram-positive bacteria without triggering multidrug resistance. However, BA is inactive against gram-negative bacteria because of its inability to cross the outer membrane of these cells, and it has strong nephrotoxicity, thus limiting its clinical applications. Nanoantibiotics can effectively localize antibiotics to the periplasmic space of bacteria while decreasing the adverse effects of antibiotics. In this study, biodegradable hydrophobic copolymers of poly (d,l-lactide-co-glycolide) (PLGA) were attached to the N-termini of BA to design a novel class of self-assembled nano-bacitracin A (nano-BAs), and their potential as antibacterial agents was evaluated in vitro and in vivo. Nano-BAs had a core-shell structure with a mean diameter <150 nm. Impressively, nano-BAs had strong antibacterial properties against both gram-positive and gram-negative bacteria, and the distribution of antibacterial activity as a function of PLGA block length was skewed toward longer PLGA chains. No cytotoxicity against HK-2 cells or human red blood cells (hRBCs) was observed in vitro, suggesting good biocompatibility. A high local density of BA mass on the surface promoted endocytotic cellular uptake, and hydrophobic interactions between the PLGA block and lipopolysaccharide (LPS) facilitated the uptake of nano-BAs, thereby leading to greater antibacterial activities. In addition, Nano-BA 5K was found to be effective in vivo, and it served as an anti-infective agent for wound healing. Collectively, this study provides a cost-effective means of developing self-assembling nano-polypeptide antibiotic candidates with a broader antibacterial spectrum and a lower toxicity than commercially available peptide antibiotics, owing to their modification with biodegradable copolymers.

Natural Pathogen Control Chemistry to Replace Toxic Treatment of Microbes and Biofilm in Cooling Towers

PubMed Central

Brouse, Lon; Brouse, Richard; Brouse, Daniel

2017-01-01

Application of toxic antibacterial agents is considered necessary to control prevalent fresh water microorganisms that grow in evaporative cooling water systems, but can adversely affect the environment and human health. However, natural antibacterial water chemistry has been applied in industrial cooling water systems for over 10 years to inhibit microorganisms with excellent results. The water chemistry method concentrates natural minerals in highly-softened water to produce elevated pH and dissolved solids, while maintaining low calcium and magnesium content. The method provides further benefits in water conservation, and generates a small volume of non-toxic natural salt concentrate for cost efficient separation and disposal if required. This report describes the antimicrobial effects of these chemistry modifications in the cooling water environment and the resultant collective inhibition of microbes, biofilm, and pathogen growth. This article also presents a novel perspective of parasitic microbiome functional relationships, including “Trojan Protozoans” and biofilms, and the function of polyvalent metal ions in the formation and inhibition of biofilms. Reducing global dependence on toxic antibacterial agents discharged to the environment is an emerging concern due to their impact on the natural microbiome, plants, animals and humans. Concurrently, scientists have concluded that discharge of antibacterial agents plays a key role in development of pathogen resistance to antimicrobials as well as antibiotics. Use of natural antibacterial chemistry can play a key role in managing the cooling water environment in a more ecologically sustainable manner. PMID:28420074

Evaluation of the antibacterial efficacy of diesters of azelaic acid.

PubMed

Charnock, Colin; Brudeli, Bjarne; Klaveness, Jo

2004-04-01

A number of diesters of the topical dermatosis treatment azelaic (nonanedioic) acid were prepared and tested for antibacterial effect. Two esters, bis-[(hexanoyloxy)methyl] nonanedioate and especially bis-[(butanoyloxy)methyl] nonanedioate showed promising activity against acne related bacteria in vitro. No activity of azelaic acid was detected in Mueller Hinton II agar at pH 7.3 when using the agar diffusion method, whereas both esters gave zones of growth inhibition. At pH 5.6, activity of azelaic acid was detected. At this pH, the zones of inhibition and MIC values obtained with azelaic acid were smaller than those of bis-[(butanoyloxy)methyl] nonanedioate for all test organisms. A preparation for topical use containing 20% (w/w) bis-[(butanoyloxy)methyl] nonanedioate, and the commercially available Skinoren (20% (w/w) azelaic acid), were compared for antibacterial effect against cutaneous bacteria using contact plate analyses of the skin. Though Skinoren was usually most effective, the differences were not statistically significant. Furthermore, bacteria surviving contact with the topical preparations were invariably more sensitive to the ester than to azelaic acid upon subculturing onto agar (pH 5.6) containing either preparation at 0.2-0.7 mg/ml. This might indicate that other factors, such as the composition of the cream base, mitigate the antibacterial activity of the ester. It is proposed that the pharmacological and microbiological properties of bis-[(butanoyloxy)methyl] nonanedioate are worthy of further study based on an extended screening of acne sufferers.

Myeloperoxidase-Halide-Hydrogen Peroxide Antibacterial System

PubMed Central

Klebanoff, Seymour J.

1968-01-01

An antibacterial effect of myeloperoxidase, a halide, such as iodide, bromide, or chloride ion, and H2O2 on Escherichia coli or Lactobacillus acidophilus is described. When L. acidophilus was employed, the addition of H2O2 was not required; however, the protective effect of catalase suggested that, in this instance, H2O2 was generated by the organisms. The antibacterial effect was largely prevented by preheating the myeloperoxidase at 80 C or greater for 10 min or by the addition of a number of inhibitors; it was most active at the most acid pH employed (5.0). Lactoperoxidase was considerably less effective than was myeloperoxidase when chloride was the halide employed. Myeloperoxidase, at high concentrations, exerted an antibacterial effect on L. acidophilus in the absence of added halide, which also was temperature- and catalase-sensitive. Peroxidase was extracted from intact guinea pig leukocytes by weak acid, and the extract with peroxidase activity had antibacterial properties which were similar, in many respects, to those of the purified preparation of myeloperoxidase. Under appropriate conditions, the antibacterial effect was increased by halides and by H2O2 and was decreased by catalase, as well as by cyanide, azide, Tapazole, and thiosulfate. This suggests that, under the conditions employed, the antibacterial properties of a weak acid extract of guinea pig leukocytes is due, in part, to its peroxidase content, particularly if a halide is present in the reaction mixture. A heat-stable antibacterial agent or agents also appear to be present in the extract. PMID:4970226

ANTIBACTERIAL ACTIVITY OF DRACONTOMELON DAO EXTRACTS ON METHICILLIN-RESISTANT S. AUREUS (MRSA) AND E. COLI MULTIPLE DRUG RESISTANCE (MDR).

PubMed

Yuniati, Yuniati; Hasanah, Nurul; Ismail, Sjarif; Anitasari, Silvia; Paramita, Swandari

2018-01-01

Staphylococcus aureus , methicillin-resistant and Escherichia coli , multidrug-resistant included in the list of antibiotic-resistant priority pathogens from WHO. As multidrug-resistant bacteria problem is increasing, it is necessary to probe new sources for identifying antimicrobial compounds. Medicinal plants represent a rich source of antimicrobial agents. One of the potential plants for further examined as antibacterial is Dracontomelon dao (Blanco) Merr. & Rolfe. The present study designed to find the antibacterial activity of D. dao stem bark extracts on Methicillin-resistant S. aureus (MRSA) and E. coli Multiple Drug Resistance (MDR), followed by determined secondary metabolites with antibacterial activity and determined the value of MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration). D. dao stem bark extracted using 60% ethanol. Disc diffusion test methods used to find the antibacterial activity, following by microdilution methods to find the value of MIC and MBC. Secondary metabolites with antibacterial activity determined by bioautography using TLC (thin layer chromatography) methods. D. dao stem bark extracts are sensitive to MSSA, MRSA and E.coli MDR bacteria. The inhibition zone is 16.0 mm in MSSA, 11.7 mm in MRSA and 10.7 mm in E. coli MDR. The entire MBC/MIC ratios for MSSA, MRSA and E.coli MDR is lower than 4. The ratio showed bactericidal effects of D. dao stem bark extracts. In TLC results, colorless bands found to be secondary metabolites with antibacterial activity. D. dao stem bark extracts are potential to develop as antibacterial agent especially against MRSA and E. coli MDR strain.

Nano-ZnO/ZnO-HAPw prepared via sol-gel method and antibacterial activities of inorganic agents on six bacteria associated with oral infections

NASA Astrophysics Data System (ADS)

Jin, Jianfeng; Liu, Wenying; Zhang, Wenyun; Chen, Qinghua; Yuan, Yanbo; Yang, Lidou; Wang, Qintao

2014-10-01

The antibacterial activity of zinc oxide (ZnO) and the strengthening of hydroxylapatite whiskers (HAPws) have been widely studied and applied. However, the antibacterial properties of ZnO-HAPws have scarcely been researched. The aim of this study was to further investigate several types of nano-ZnO morphologies of ZnO-HAPws that were prepared using the sol-gel method at different pondus hydrogenii (pH) values and temperatures. The four morphologies of ZnO-HAPws that were investigated here were granule, triangle, short rod and disc type, and these morphologies were investigated at 70 °C at pH 6.4, 37 °C at pH 6.6, 70 °C at pH 6.6 and 70 °C at pH 6.6, respectively. Next, the antibacterial activity of ZnO-HAPw was compared to that of nano-ZnO, commercially available ZnO and tetrapod-like ZnO whiskers (T-ZnOw) with six bacteria that are associated with oral infections: Streptococcus mutans, Lactobacillus casei, Candida albicans, Actinomyces viscosus, Staphylococcus aureus and Escherichia coli. The results of examinations of the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) showed that the antibacterial activity of ZnO-HAPw exceeded that of the commercially available ZnO and T-ZnOw. Additionally, analysis of variance (ANOVA) analysis of the MBCs revealed that the four tested antibacterial agents had significantly different effects on S. mutans ( F = 8.940; P = 0.006), S. aureus ( F = 6.924; P = 0.013) and E. coli ( F = 4.468; P = 0.04). ANOVA analyses of the MICs revealed that the four tested antibacterial agents had significantly different effects on S. mutans ( F = 6.183; P = 0.018), A. viscosus ( F = 4.531; P = 0.039) and S. aureus ( F = 18.976; P = 0.001).

Effect of primycin on growth-arrested cultures and cell integrity of Staphylococcus aureus.

PubMed

Feiszt, Péter; Schneider, György; Emődy, Levente

2017-06-01

Bactericidal effect against non-dividing bacteria is a very advantageous, but rare characteristic among antimicrobial agents, mostly possessed by those affecting the cell membrane. These kinds of agents can kill bacterial cells without lysis. We assessed these characteristics on primycin, a topical anti-staphylococcal agent highly effective against prevalent multiresistant strains, as it also acts on the cell membrane. In time-kill studies, primycin preserved its bactericidal activity against growth-arrested Staphylococcus aureus cultures. The bactericidal action was slower against growth-arrested cultures compared to the exponentially growing ones to different extents depending on the manner of arrest. The bactericidal effect was less influenced by stringent response and by protein synthesis inhibition, proving that it does not depend on metabolic activity. In contrast, uncoupling of the membrane potential predominantly slowed, and low temperature almost stopped killing of bacteria. In consideration of published data, these facts suggest that the antibacterial action of primycin involves disrupting of the membrane potential, and is predominantly influenced by the membrane fluidity. Optical density measurements and transmission electron microscopy verified that primycin kills bacterial cells without lysis. These results reveal favorable characteristics of primycin and point to, and broaden the knowledge on its membrane-targeted effect.

Development and Sequential Analysis of a New Multi-Agent, Anti-Acne Formulation Based on Plant-Derived Antimicrobial and Anti-Inflammatory Compounds.

PubMed

Saviuc, Crina; Ciubucă, Bianca; Dincă, Gabriela; Bleotu, Coralia; Drumea, Veronica; Chifiriuc, Mariana-Carmen; Popa, Marcela; Gradisteanu Pircalabioru, Gratiela; Marutescu, Luminita; Lazăr, Veronica

2017-01-17

The antibacterial and anti-inflammatory potential of natural, plant-derived compounds has been reported in many studies. Emerging evidence indicates that plant-derived essential oils and/or their major compounds may represent a plausible alternative treatment for acne, a prevalent skin disorder in both adolescent and adult populations. Therefore, the purpose of this study was to develop and subsequently analyze the antimicrobial activity of a new multi-agent, synergic formulation based on plant-derived antimicrobial compounds (i.e., eugenol, β-pinene, eucalyptol, and limonene) and anti-inflammatory agents for potential use in the topical treatment of acne and other skin infections. The optimal antimicrobial combinations selected in this study were eugenol/β-pinene/salicylic acid and eugenol/β-pinene/2-phenoxyethanol/potassium sorbate. The possible mechanisms of action revealed by flow cytometry were cellular permeabilization and inhibition of efflux pumps activity induced by concentrations corresponding to sub-minimal inhibitory (sub-MIC) values. The most active antimicrobial combination represented by salycilic acid/eugenol/β-pinene/2-phenoxyethanol/potassium sorbate was included in a cream base, which demonstrated thermodynamic stability and optimum microbiological characteristics.

Synthesis and Bioactivity Evaluation of N-Arylsulfonylindole Analogs Bearing a Rhodanine Moiety as Antibacterial Agents.

PubMed

Song, Ming-Xia; Li, Song-Hui; Peng, Jiao-Yang; Guo, Ting-Ting; Xu, Wen-Hui; Xiong, Shao-Feng; Deng, Xian-Qing

2017-06-14

Due to the rapidly growing bacterial resistance to antibiotics and the scarcity of novel agents under development, bacterial infections are still a pressing global problem, making new types of antibacterial agents, which are effective both alone and in combination with traditional antibiotics, urgently needed. In this paper, seven series of N -arylsulfonylindole analogs 5 - 11 bearing rhodanine moieties were synthesized, characterized, and evaluated for antibacterial activity. According to the in vitro antimicrobial results, half of the synthesized compounds showed potent inhibition against four Gram-positive bacteria, with MIC values in the range of 0.5-8 µg/mL. For multidrug-resistant strains, compounds 6a and 6c were the most potent, with MIC values of 0.5 µg/mL, having comparable activity to gatifloxacin, moxiflocaxin and norfloxacin and being 128-fold more potent than oxacillin (MIC = 64 µg/mL) and 64-fold more active than penicillin (MIC = 32 µg/mL) against Staphylococcus aureus ATCC 43300 .

Comparison of the cidal activity of tea tree oil and terpinen-4-ol against clinical bacterial skin isolates and human fibroblast cells.

PubMed

Loughlin, R; Gilmore, B F; McCarron, P A; Tunney, M M

2008-04-01

The aim of this study was to compare both the antimicrobial activity of terpinen-4-ol and tea tree oil (TTO) against clinical skin isolates of meticillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS) and their toxicity against human fibroblast cells. Antimicrobial activity was compared by using broth microdilution and quantitative in vitro time-kill test methods. Terpinen-4-ol exhibited significantly greater bacteriostatic and bactericidal activity, as measured by minimum inhibitory and bactericidal concentrations, respectively, than TTO against both MRSA and CoNS isolates. Although not statistically significant, time-kill studies also clearly showed that terpinen-4-ol exhibited greater antimicrobial activity than TTO. Comparison of the toxicity of terpinen-4-ol and TTO against human fibroblasts revealed that neither agent, at the concentrations tested, were toxic over the 24-h test period. Terpinen-4-ol is a more potent antibacterial agent against MRSA and CoNS isolates than TTO with neither agent exhibiting toxicity to fibroblast cells at the concentrations tested. Terpinen-4-ol should be considered for inclusion as a single agent in products formulated for topical treatment of MRSA infection. However, further work would initially be required to ensure that resistance would not develop with the use of terpinen-4-ol as a single agent.

[In vitro comparison of antibacterial properties of antiseptics used in periodontology].

PubMed

Bezdenezhnykh, D S; Rusanova, E V; Nikitin, A A; Malychenko, N V

2012-01-01

Antibacterial properties of antiseptics most commonly used in periodontology were examined in vitro showing al agents containing chlorhexidine to be the most effective against gram-negative (E. coli), gram-positive (staphylococcus, streptococcus, enterococcus) germs as well as а C. аlbicans.

Modification of titanium surfaces by adding antibiotic-loaded PHB spheres and PEG for biomedical applications.

PubMed

Rodríguez-Contreras, Alejandra; Marqués-Calvo, María Soledad; Gil, Francisco Javier; Manero, José María

2016-08-01

Novel researches are focused on the prevention and management of post-operative infections. To avoid this common complication of implant surgery, it is preferable to use new biomaterials with antibacterial properties. Therefore, the aim of this work is to develop a method of combining the antibacterial properties of antibiotic-loaded poly(3-hydroxybutyrate) (PHB) nano- and micro-spheres and poly(ethylene glycol) (PEG) as an antifouling agent, with titanium (Ti), as the base material for implants, in order to obtain surfaces with antibacterial activity. The Ti surfaces were linked to both PHB particles and PEG by a covalent bond. This attachment was carried out by firstly activating the surfaces with either Oxygen plasma or Sodium hydroxide. Further functionalization of the activated surfaces with different alkoxysilanes allows the reaction with PHB particles and PEG. The study confirms that the Ti surfaces achieved the antibacterial properties by combining the antibiotic-loaded PHB spheres, and PEG as an antifouling agent.

Novel substituted (pyridin-3-yl)phenyloxazolidinones: antibacterial agents with reduced activity against monoamine oxidase A and increased solubility.

PubMed

Reck, Folkert; Zhou, Fei; Eyermann, Charles J; Kern, Gunther; Carcanague, Dan; Ioannidis, Georgine; Illingworth, Ruth; Poon, Grace; Gravestock, Michael B

2007-10-04

Oxazolidinones represent a new and promising class of antibacterial agents. Current research in this area is mainly concentrated on improving the safety profile and the antibacterial spectrum. Oxazolidinones bearing a (pyridin-3-yl)phenyl moiety (e.g., 3) generally show improved antibacterial activity compared to linezolid but suffer from potent monoamine oxidase A (MAO-A) inhibition and low solubility. We now disclose the finding that new analogues of 3 with acyclic substituents on the pyridyl moiety exhibit excellent activity against Gram-positive pathogens, including linezolid-resistant Streptococcus pneumoniae. Generally, more bulky substituents yielded significantly reduced MAO-A inhibition relative to the unsubstituted compound 3. The MAO-A SAR can be rationalized on the basis of docking studies using a MAO-A/MAO-B homology model. Solubility was enhanced with incorporation of polar groups. One optimized analogue, compound 13, showed low clearance in the rat and efficacy against S. pneumoniae in a mouse pneumonia model.

Design and evaluation of anacardic acid derivatives as anticavity agents.

PubMed

Green, Ivan R; Tocoli, Felismino E; Lee, Sang Hwa; Nihei, Ken-ichi; Kubo, Isao

2008-06-01

On the basis of antibacterial anacardic acids, 6-pentadecenylsalicylic acids, isolated from the cashew apple, Anacardium occidentale L. (Anacardiaceae), a series of 6-alk(en)ylsalicylic acids were synthesized and tested for their antibacterial activity against Streptococcus mutans ATCC 25175. Among them, 6-(4',8'-dimethylnonyl)salicylic acid was found to exhibit the most potent antibacterial activity against this cariogenic bacterium with the minimum inhibition concentration (MIC) of 0.78 microg/ml.

Antibacterial effect of cationic porphyrazines and anionic phthalocyanine and their interaction with plasmid DNA

NASA Astrophysics Data System (ADS)

Hassani, Leila; Hakimian, Fatemeh; Safaei, Elham; Fazeli, Zahra

2013-11-01

Resistance to antibiotics is a public health issue and identification of new antibacterial agents is one of the most important goals of pharmacological research. Among the novel developed antibacterial agents, porphyrin complexes and their derivatives are ideal candidates for use in medical applications. Phthalocyanines differ from porphyrins by having nitrogen atoms link the individual pyrrol units. The aza analogues of the phthalocyanines (azaPcs) such as tetramethylmetalloporphyrazines are heterocyclic Pc analogues. In this investigation, interaction of an anionic phthalocyanine (Cu(PcTs)) and two cationic tetrapyridinoporphyrazines including [Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+ complexes with plasmid DNA was studied using spectroscopic and gel electrophoresis methods. In addition, antibacterial effect of the complexes against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was investigated using dilution test method. The results indicated that both porphyrazines have significant antibacterial properties, but Cu(PcTs) has weak antibacterial effect. Compairing the binding of the phthalocyanine and the porphyrazines to DNA demonstrated that the interaction of cationic porphyrazines is stronger than the anionic phthalocyanine remarkably. The extent of hypochromicity and red shift of absorption spectra indicated preferential intercalation of the two porphyrazine into the base pairs of DNA helix. Gel electrophoresis result implied Cu(2,3-tmtppa) and Cu(3,4-tmtppa) are able to perform cleavage of the plasmid DNA. Consequently, DNA binding and cleavage might be one of the antibacterial mechanisms of the complexes.

Functional gold nanoparticle-based antibacterial agents for nosocomial and antibiotic-resistant bacteria.

PubMed

Kuo, Yen-Ling; Wang, Sin-Ge; Wu, Ching-Yi; Lee, Kai-Chieh; Jao, Chan-Jung; Chou, Shiu-Huey; Chen, Yu-Chie

2016-10-01

Medical treatments for bacterial-infections have become challenging because of the emergence of antibiotic-resistant bacterial strains. Thus, new therapeutics and antibiotics must be developed. Arginine and tryptophan can target negatively-charged bacteria and penetrate bacterial cell membrane, respectively. Synthetic-peptides containing arginine, tryptophan and cysteine termini, in other words, (DVFLG)2REEW4C and (DVFLG)2REEW2C, as starting materials were mixed with aqueous tetrachloroauric acid to generate peptide-immobilized gold nanoparticles (i.e., [DVFLG]2REEW4C-AuNPs and [DVFLG]2REEW2C-AuNPs) through one-pot reactions. The peptide immobilized AuNPs exhibit targeting capacity and antibacterial activity. Furthermore, (DVFLG)2REEW4C-AuNPs immobilized with a higher number of tryptophan molecules possess more effective antibacterial capacity than (DVFLG)2REEW2C-AuNPs. Nevertheless, they are not harmful for animal cells. The feasibility of using the peptide-AuNPs to inhibit the cell growth of bacterium-infected macrophages was demonstrated. These results suggested that the proposed antibacterial AuNPs are effective antibacterial agents for Staphylococci, Enterococci and antibiotic-resistant bacterial strains. [Formula: see text].

New target for inhibition of bacterial RNA polymerase: 'switch region'.

PubMed

Srivastava, Aashish; Talaue, Meliza; Liu, Shuang; Degen, David; Ebright, Richard Y; Sineva, Elena; Chakraborty, Anirban; Druzhinin, Sergey Y; Chatterjee, Sujoy; Mukhopadhyay, Jayanta; Ebright, Yon W; Zozula, Alex; Shen, Juan; Sengupta, Sonali; Niedfeldt, Rui Rong; Xin, Cai; Kaneko, Takushi; Irschik, Herbert; Jansen, Rolf; Donadio, Stefano; Connell, Nancy; Ebright, Richard H

2011-10-01

A new drug target - the 'switch region' - has been identified within bacterial RNA polymerase (RNAP), the enzyme that mediates bacterial RNA synthesis. The new target serves as the binding site for compounds that inhibit bacterial RNA synthesis and kill bacteria. Since the new target is present in most bacterial species, compounds that bind to the new target are active against a broad spectrum of bacterial species. Since the new target is different from targets of other antibacterial agents, compounds that bind to the new target are not cross-resistant with other antibacterial agents. Four antibiotics that function through the new target have been identified: myxopyronin, corallopyronin, ripostatin, and lipiarmycin. This review summarizes the switch region, switch-region inhibitors, and implications for antibacterial drug discovery. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pyrazole derivatives as antitumor, anti-inflammatory and antibacterial agents.

PubMed

Liu, Jia-Jia; Zhao, Meng-Yue; Zhang, Xin; Zhao, Xin; Zhu, Hai-Liang

2013-11-01

Within the past years, many researches on the synthesis, structure-activity relationships (SAR), antitumor, antiinflammatory and anti-bacterial activities of the pyrazole derivatives have been reported. Several pyrazole derivatives possess important pharmacological activities and they have been proved useful materials in drug research. Pyrazole derivatives play an important role in antitumor agents because of their good inhibitory activity against BRAF(V600E), EGFR, telomerase, ROS Receptor Tyrosine Kinase and Aurora-A kinase. In addition, pyrazole derivatives also show good antiinflammatory and anti-bacterial activities. In this review, the bioactivities of the pyrazole derivatives mentioned above will be summarized in detail. We sincerely hope that increasing knowledge of the SAR and cellular processes underlying the bioactivity of pyrazole derivatives will be beneficial to the rational design of new generation of small molecule drugs.

Thymbra capitata essential oil as potential therapeutic agent against Gardnerella vaginalis biofilm-related infections.

PubMed

Machado, Daniela; Gaspar, Carlos; Palmeira-de-Oliveira, Ana; Cavaleiro, Carlos; Salgueiro, Lígia; Martinez-de-Oliveira, José; Cerca, Nuno

2017-04-01

To evaluate the antibacterial activity of Thymbra capitata essential oil and its main compound, carvacrol, against Gardnerella vaginalis grown planktonically and as biofilms, and its effect of vaginal lactobacilli. Minimal inhibitory concentration, minimal lethal concentration determination and flow cytometry analysis were used to assess the antibacterial effect against planktonic cells. Antibiofilm activity was measured through quantification of biomass and visualization of biofilm structure by confocal laser scanning microscopy. T. capitata essential oil and carvacrol exhibited a potent antibacterial activity against G. vaginalis cells. Antibiofilm activity was more evident with the essential oil than carvacrol. Furthermore, vaginal lactobacilli were significantly more tolerant to the essential oil. T. capitata essential oil stands up as a promising therapeutic agent against G. vaginalis biofilm-related infections.

Antibacterial agents in composite restorations for the prevention of dental caries.

PubMed

Pereira-Cenci, Tatiana; Cenci, Maximiliano S; Fedorowicz, Zbys; Azevedo, Marina

2013-12-17

Dental caries is a multifactorial disease in which the fermentation of food sugars by bacteria from the biofilm (dental plaque) leads to localised demineralisation of tooth surfaces, which may ultimately result in cavity formation. Resin composites are widely used in dentistry to restore teeth. These restorations can fail for a number of reasons, such as secondary caries, and restorative material fracture and other minor reasons. From these, secondary caries, which are caries lesions developed adjacent to restorations, is the main cause for restorations replacement. The presence of antibacterials in both the filling material and the bonding systems would theoretically be able to affect the initiation and progression of caries adjacent to restorations. This is an update of the Cochrane review published in 2009. To assess the effects of antibacterial agents incorporated into composite restorations for the prevention of dental caries. We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 23 July 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 6), MEDLINE via OVID (1946 to 23 July 2013) and EMBASE via OVID (1980 to 23 July 2013). We searched the US National Institutes of Health Trials Register (http://clinicaltrials.gov), the metaRegister of Controlled Trials (www.controlled-trials.com) and the World Health Organization International Clinical Trials Registry platform (www.who.int/trialsearch) for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. Randomised controlled trials comparing resin composite restorations containing antibacterial agents with composite restorations not containing antibacterial agents. Two review authors conducted screening of studies in duplicate and independently, and although no eligible trials were identified, the two authors had planned to extract data independently and assess trial quality using standard Cochrane Collaboration methodologies. We retrieved 308 references to studies, none of which matched the inclusion criteria for this review and all of which were excluded. We were unable to identify any randomised controlled trials on the effects of antibacterial agents incorporated into composite restorations for the prevention of dental caries. The absence of high level evidence for the effectiveness of this intervention emphasises the need for well designed, adequately powered, randomised controlled clinical trials. Thus, conclusions remain the same as the previously published review, with no included clinical trials.

Synthesis, anti-MRSA, and anti-VRE activity of hemin conjugates with amino acids and branched peptides.

PubMed

Okorochenkov, Sergei A; Zheltukhina, Galina A; Mirchink, Elena P; Isakova, Elena B; Feofanov, Alexey V; Nebolsin, Vladimir E

2013-10-01

The increasing prevalence of antibiotic-resistant bacterial strains has necessitated the synthesis of novel antibacterial agents. It was previously shown that naturally occurring metalloporphyrin hemin possesses dark antibacterial activity against Gram-positive bacteria. To improve hemin antibacterial activity, we synthesized a number of hemin conjugates with amino acids and branched peptides. Arginine-containing hemin conjugates demonstrated high antibacterial activity against Gram-positive bacteria including methicillin- and vancomycin-resistant strains in vitro. Most of the synthesized conjugates showed low toxicity against human erythrocytes and leukocytes. © 2013 John Wiley & Sons A/S.

Simultaneous Delivery of Multiple Antibacterial Agents from Additively Manufactured Porous Biomaterials to Fully Eradicate Planktonic and Adherent Staphylococcus aureus.

PubMed

Bakhshandeh, S; Gorgin Karaji, Z; Lietaert, K; Fluit, A C; Boel, C H E; Vogely, H C; Vermonden, T; Hennink, W E; Weinans, H; Zadpoor, A A; Amin Yavari, S

2017-08-09

Implant-associated infections are notoriously difficult to treat and may even result in amputation and death. The first few days after surgery are the most critical time to prevent those infections, preferably through full eradication of the micro-organisms entering the body perioperatively. That is particularly important for patients with a compromised immune system such as orthopedic oncology patients, as they are at higher risk for infection and complications. Full eradication of bacteria is, especially in a biofilm, extremely challenging due to the toxicity barrier that prevents delivery of high doses of antibacterial agents. This study aimed to use the potential synergistic effects of multiple antibacterial agents to prevent the use of toxic levels of these agents and achieve full eradication of planktonic and adherent bacteria. Silver ions and vancomycin were therefore simultaneously delivered from additively manufactured highly porous titanium implants with an extremely high surface area incorporating a bactericidal coating made from chitosan and gelatin applied by electrophoretic deposition (EPD). The presence of the chitosan/gelatin (Ch+Gel) coating, Ag, and vancomycin (Vanco) was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The release of vancomycin and silver ions continued for at least 21 days as measured by inductively coupled plasma (ICP) and UV-spectroscopy. Antibacterial behavior against Staphylococcus aureus, both planktonic and in biofilm, was evaluated for up to 21 days. The Ch+Gel coating showed some bactericidal behavior on its own, while the loaded hydrogels (Ch+Gel+Ag and Ch+Gel+Vanco) achieved full eradication of both planktonic and adherent bacteria without causing significant levels of toxicity. Combining silver and vancomycin improved the release profiles of both agents and revealed a synergistic behavior that further increased the bactericidal effects.

Simultaneous Delivery of Multiple Antibacterial Agents from Additively Manufactured Porous Biomaterials to Fully Eradicate Planktonic and Adherent Staphylococcus aureus

PubMed Central

2017-01-01

Implant-associated infections are notoriously difficult to treat and may even result in amputation and death. The first few days after surgery are the most critical time to prevent those infections, preferably through full eradication of the micro-organisms entering the body perioperatively. That is particularly important for patients with a compromised immune system such as orthopedic oncology patients, as they are at higher risk for infection and complications. Full eradication of bacteria is, especially in a biofilm, extremely challenging due to the toxicity barrier that prevents delivery of high doses of antibacterial agents. This study aimed to use the potential synergistic effects of multiple antibacterial agents to prevent the use of toxic levels of these agents and achieve full eradication of planktonic and adherent bacteria. Silver ions and vancomycin were therefore simultaneously delivered from additively manufactured highly porous titanium implants with an extremely high surface area incorporating a bactericidal coating made from chitosan and gelatin applied by electrophoretic deposition (EPD). The presence of the chitosan/gelatin (Ch+Gel) coating, Ag, and vancomycin (Vanco) was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The release of vancomycin and silver ions continued for at least 21 days as measured by inductively coupled plasma (ICP) and UV-spectroscopy. Antibacterial behavior against Staphylococcus aureus, both planktonic and in biofilm, was evaluated for up to 21 days. The Ch+Gel coating showed some bactericidal behavior on its own, while the loaded hydrogels (Ch+Gel+Ag and Ch+Gel+Vanco) achieved full eradication of both planktonic and adherent bacteria without causing significant levels of toxicity. Combining silver and vancomycin improved the release profiles of both agents and revealed a synergistic behavior that further increased the bactericidal effects. PMID:28696671

New treatment options for lower respiratory tract infections.

PubMed

Kocsis, Bela; Szabo, Dora

2017-09-01

Community-acquired pneumonia (CAP) and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) are among the most frequent lower respiratory tract infections (LRTIs). They represent an increased morbidity and mortality rate in adults. Areas covered: This review describes recent advances regarding solithromycin, zabofloxacin and delafoxacin antibacterial agents that have been recently developed for treatment of CAP and in AECOPD. All of them have been introduced into phase III clinical trials. We will be summarising chemical structures, pharmacokinetics, antibacterial efficacy and toxicity of these agents. The manuscript has been prepared based on available scientific publications. Expert opinion: Novel agents of known antimicrobial classes have been developed that demonstrate treatment options in CAP and in AECOPD. Antimicrobials discussed in this review showed bactericide effect against major respiratory tract pathogens. Each has multiple targets in bacteria, thus enabling them for more potency, even against strains exhibiting resistance to commonly used antibiotics. Solithromycin, delafloxacin and zabofloxcian demonstrate broad-spectrum antibacterial activity together with other beneficial features like intracellular accumulation, anti-inflammatory effect and inhibition of biofilm production. These agents showed moderately severe or mild adverse events and demonstrated favourable tissue penetration. These features can make solithromycin, zabofloxacin and delafloxacin treatment options in LRTIs.

Public funding for research on antibacterial resistance in the JPIAMR countries, the European Commission, and related European Union agencies: a systematic observational analysis.

PubMed

Kelly, Ruth; Zoubiane, Ghada; Walsh, Desmond; Ward, Rebecca; Goossens, Herman

2016-04-01

Antibacterial resistant infections are rising continuously, resulting in increased morbidity and mortality worldwide. With no new antibiotic classes entering the market and the possibility of returning to the pre-antibiotic era, the Joint Programming Initiative on Antimicrobial Resistance (JPIAMR) was established to address this problem. We aimed to quantify the scale and scope of publicly funded antibacterial resistance research across JPIAMR countries and at the European Union (EU) level to identify gaps and future opportunities. We did a systematic observational analysis examining antibacterial resistance research funding. Databases of funding organisations across 19 countries and at EU level were systematically searched for publicly funded antibacterial resistance research from Jan 1, 2007, to Dec 31, 2013. We categorised studies on the basis of the JPIAMR strategic research agenda's six priority topics (therapeutics, diagnostics, surveillance, transmission, environment, and interventions) and did an observational analysis. Only research funded by public funding bodies was collected and no private organisations were contacted for their investments. Projects in basic, applied, and clinical research, including epidemiological, public health, and veterinary research and trials were identified using keyword searches by organisations, and inclusion criteria were based on the JPIAMR strategic research agenda's six priority topics, using project titles and abstracts as filters. We identified 1243 antibacterial resistance research projects, with a total public investment of €1·3 billion across 19 countries and at EU level, including public investment in the Innovative Medicines Initiative. Of the total amount invested in antibacterial resistance research across the time period, €646·6 million (49·5%) was invested at the national level and €659·2 million (50·5%) at the EU level. When projects were classified under the six priority topics we found that 763 (63%) of 1208 projects funded at national level were within the area of therapeutics, versus 185 (15%) in transmission, 131 (11%) in diagnostics, 53 (4%) in interventions, and only 37 (3%) in environment and 39 (3%) in surveillance. This was the first systematic analysis of research funding of antibacterial resistance of this scale and scope, which relied on the availability and accuracy of data from organisations included. Large variation was seen between countries both in terms of number of projects and associated investment and across the six priority topics. To determine the future direction of JPIAMR countries a clear picture of the funding landscape across Europe and Canada is needed. Countries should work together to increase the effect of research funding by strengthening national and international coordination and collaborations, harmonising research activities, and collectively pooling resources to fund multidisciplinary projects. The JPIAMR have developed a publicly available database to document the antibacterial resistance research collected and can be used as a baseline to analyse funding from 2014 onwards. JPIAMR and the European Commission. Copyright © 2016 Kelly et al. Open Access article distributed under the terms of CC BY. Published by Elsevier Ltd.. All rights reserved.

Comparison between topical honey and mafenide acetate in treatment of auricular burn.

PubMed

Hashemi, Basir; Bayat, Akbar; Kazemei, Tayebe; Azarpira, Negar

2011-01-01

The auricle is a frequently injured part of the head and neck during thermal injury leading to ear deformity. The burned ear represents one of the most difficult problems for reconstructive surgeons. Mafenide acetate is a topical agent used routinely for these patients, but it has some disadvantages including painful application and allergic rash. Some authors have reported the healing effect and antibacterial activity of honey. The study reported here was undertaken to compare the effect of honey and mafenide acetate on auricular burn in rabbit. In our study, although the pathologic score of the honey group was better than that of the mafenide group both on 14 and 21 days after burning, it was not statistically significant. In the mafenide acetate group, deep complication of burn (chondritis) was significantly lower than that of the honey group. In conclusion, in contrast to healing and antibiotic activity reported for honey, it may have failure in preventing deep bacterial complications of wound (like chondritis). So in deep wounds, the use of honey as dressing is not recommended. Copyright © 2011 Elsevier Inc. All rights reserved.

Design and Solution-Phase Synthesis of Membrane-Targeting Lipopeptides with Selective Antibacterial Activity.

PubMed

Konai, Mohini M; Adhikary, Utsarga; Haldar, Jayanta

2017-09-18

Designing selective antibacterial molecules remains an unmet goal in the field of membrane-targeting agents. Herein, we report the rational design and synthesis of a new class of lipopeptides, which possess highly selective bacterial killing over mammalian cells. The selective interaction with bacterial over mammalian membranes was established through various spectroscopic, as well as microscopic experiments, including biophysical studies with the model membranes. A detailed antibacterial structure-activity relationship was delineated after preparing a series of molecules consisting of the peptide moieties with varied sequence of amino acids, such as d-phenylalanine, d-leucine, and d-lysine. Antibacterial activity was found to vary with the nature and positioning of hydrophobicity in the molecules, as well as number of positive charges. Optimized lipopeptide 9 did not show any hemolytic activity even at 1000 μg mL -1 and displayed >200-fold and >100-fold selectivity towards S. aureus and E. coli, respectively. More importantly, compound 9 was found to display good antibacterial activity (MIC 6.3-12.5 μg mL -1 ) against the five top most critical bacteria according to World Health Organization (WHO) priority pathogens list. Therefore, the results suggested that this new class of lipopeptides bear real promises for the development as future antibacterial agents. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Besifloxacin, a novel fluoroquinolone, has broad-spectrum in vitro activity against aerobic and anaerobic bacteria.

PubMed

Haas, Wolfgang; Pillar, Chris M; Zurenko, Gary E; Lee, Jacqueline C; Brunner, Lynne S; Morris, Timothy W

2009-08-01

The antibacterial spectrum of besifloxacin, a novel fluoroquinolone recently approved for treatment of ocular infections, was studied using 2,690 clinical isolates representing 40 species. Overall, besifloxacin was the most potent agent tested against gram-positive pathogens and anaerobes and was generally equivalent to comparator fluoroquinolones in activity against most gram-negative pathogens. Besifloxacin demonstrated potent, broad-spectrum activity, which was particularly notable against gram-positive and gram-negative isolates that were resistant to other fluoroquinolones and classes of antibacterial agents.

Comparison of quaternary ammonium-containing with nano-silver-containing adhesive in antibacterial properties and cytotoxicity

PubMed Central

Li, Fang; Weir, Michael D.; Chen, Jihua; Xu, Hockin H. K.

2013-01-01

Objective Antibacterial primer and adhesive are promising to help combat biofilms and recurrent caries. The objectives of this study were to compare novel bonding agent containing quaternary ammonium dimethacrylate (QADM) with bonding agent containing nanoparticles of silver (NAg) in antibacterial activity, contact-inhibition vs. long-distance inhibition, glucosyltransferases (gtf) gene expressions, and cytotoxicity for the first time. Methods QADM and NAg were incorporated into Scotchbond Multi-Purpose adhesive and primer. Microtensile dentin bond strength was measured. Streptococcus mutans (S. mutans) biofilm on resin surface (contact-inhibition) as well as S. mutans in culture medium away from the resin surface (long-distance inhibition) were tested for metabolic activity, colony-forming units (CFU), lactic acid production, and gtf gene expressions. Eluents from cured primer/adhesive samples were used to examine cytotoxicity against human gingival fibroblasts. Results Bonding agent with QADM greatly reduced CFU and lactic acid of biofilms on the resin surface (p < 0.05), while having no effect on S. mutans in culture medium away from the resin surface. In contrast, bonding agent with NAg inhibited not only S. mutans on the resin surface, but also S. mutans in culture medium away from the resin surface. Bonding agent with QADM suppressed gtfB, gtfC and gtfD gene expressions of S. mutans on its surface, but not away from its surface. Bonding agent with NAg suppressed S. mutans gene expressions both on its surface and away from its surface. Bonding agents with QADM and NAg did not adversely affect microtensile bond strength or fibroblast cytotoxicity, compared to control (p > 0.1). Significance QADM-containing adhesive had contact-inhibition and inhibited bacteria on its surface, but not away from its surface. NAg-containing adhesive had long-distance killing capability and inhibited bacteria on its surface and away from its surface. The novel antibacterial adhesives are promising for caries-inhibition restorations, and QADM and NAg could be complimentary agents in inhibiting bacteria on resin surface as well as away from resin surface. PMID:23428077

Diversity of Endophytic Bacteria in a Fern Species Dryopteris uniformis (Makino) Makino and Evaluation of Their Antibacterial Potential Against Five Foodborne Pathogenic Bacteria.

PubMed

Das, Gitishree; Park, Seonjoo; Baek, Kwang-Hyun

2017-05-01

The fern plant Dryopteris uniformis has traditionally been used in herbal medicine and possesses many biological activities. This study was conducted to explore the endophytic bacterial diversity associated with D. uniformis and evaluate their antibacterial potential against foodborne pathogenic bacteria (FPB). Among 51 isolated endophytic bacteria (EB), 26 EB were selected based on their morphological characteristics and identified by 16S rRNA gene analysis. The distribution of EB was diverse in the leaf and the stem/root tissues. When the EB were screened for antibacterial activity against five FPB, Listeria monocytogenes, Salmonella Typhimurium, Bacillus cereus, Staphylococcus aureus, and Escherichia coli O157:H7, four EB Bacillus sp. cryopeg, Paenibacillus sp. rif200865, Staphylococcus warneri, and Bacillus psychrodurans had a broad spectrum of antibacterial activity (9.58 ± 0.66 to 21.47 ± 0.27 mm inhibition zone). The butanol solvent extract of B. sp. cryopeg and P. sp. rif200865 displayed effective antibacterial activity against the five FPB, which was evident from the scanning electron microscopy with irregular or burst cell morphology in the EB-treated bacteria compared to smooth and regular cells in case of the control bacteria. The minimum inhibitory concentration and minimum bactericidal concentration values ranged between 250-500 μg/mL and 500-100 μg/mL, respectively. The above outcomes signify the huge prospective of the selected EB in the food industry. Overall, the above results suggested that D. uniformis contains several culturable EB that possess effective antibacterial compounds, and that EB can be utilized as a source of natural antibacterial agents for their practical application in food industry to control the spread of FPB as a natural antibacterial agent.

In vitro antibacterial and cytotoxicity assessments of an orthodontic bonding agent containing benzalkonium chloride.

PubMed

Saito, Kayo; Hayakawa, Tohru; Kawabata, Rihito; Meguro, Daijiro; Kasai, Kazutaka

2009-03-01

To assess the antibacterial activity and cytotoxicity of an orthodontic bonding material containing an antibacterial agent. Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]) resin was mixed with benzalkonium chloride (BAC) to obtain final BAC concentrations of 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5.0% (wt/ wt). Antibacterial activity against Streptococcus mutans and Streptococcus sobrinus was evaluated by soaking the BAC-resin in distilled water at 37 degrees C for periods of 30, 90, and 180 days. Antibacterial activity of the BAC-resin was measured by the disk diffusion method, and the inhibition zone around each sample was measured and recorded. For evaluation of cytotoxicity, BAC-resin samples were put into cell culture inserts placed above human gingival cells and were incubated at 37 degrees C for 1, 3, and 6 days. Cytotoxicity was assessed with a tetrazolium bromide reduction assay. The antibacterial activity of BAC-incorporated resin samples decreased significantly after immersion in water for 180 days, regardless of BAC concentration. The antibacterial activity of nonimmersed resin containing 0.25% or 1.75% BAC was comparable with that of 5.0% BAC-resin immersed for 180 days. In cytotoxicity tests, most cells died when exposed to resins containing 1.75%, 2.5%, and 5% BAC. No difference was observed between resins containing 0.25% and 0.75% BAC at 1, 3, and 6 days of culture. The addition of BAC to 4-META/MMA-TBB resin confers an antibacterial effect even after immersion in water, and 4-META/MMA-TBB resin containing 0.25% to 0.75% BAC has no significant cytotoxic effect.

Antibacterial agent triclosan suppresses RBL-2H3 mast cell function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmer, Rachel K., E-mail: rachel.palmer@maine.edu; Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469; Hutchinson, Lee M.

2012-01-01

Triclosan is a broad-spectrum antibacterial agent, which has been shown previously to alleviate human allergic skin disease. The purpose of this study was to investigate the hypothesis that the mechanism of this action of triclosan is, in part, due to effects on mast cell function. Mast cells play important roles in allergy, asthma, parasite defense, and carcinogenesis. In response to various stimuli, mast cells degranulate, releasing allergic mediators such as histamine. In order to investigate the potential anti-inflammatory effect of triclosan on mast cells, we monitored the level of degranulation in a mast cell model, rat basophilic leukemia cells, clonemore » 2H3. Having functional homology to human mast cells, as well as a very well defined signaling pathway leading to degranulation, this cell line has been widely used to gain insight into mast-cell driven allergic disorders in humans. Using a fluorescent microplate assay, we determined that triclosan strongly dampened the release of granules from activated rat mast cells starting at 2 μM treatment, with dose-responsive suppression through 30 μM. These concentrations were found to be non-cytotoxic. The inhibition was found to persist when early signaling events (such as IgE receptor aggregation and tyrosine phosphorylation) were bypassed by using calcium ionophore stimulation, indicating that the target for triclosan in this pathway is likely downstream of the calcium signaling event. Triclosan also strongly suppressed F-actin remodeling and cell membrane ruffling, a physiological process that accompanies degranulation. Our finding that triclosan inhibits mast cell function may explain the clinical data mentioned above and supports the use of triclosan or a mechanistically similar compound as a topical treatment for allergic skin disease, such as eczema. -- Highlights: ►The effects of triclosan on mast cell function using a murine mast cell model. ►Triclosan strongly inhibits degranulation of mast cells. ►Triclosan suppresses membrane ruffling of activated mast cells. ►Triclosan's effects persist when early mast cell signaling events are bypassed. ►Supports use of triclosan as a topical treatment for eczema.« less

Prevalence of bacteria and fungi in athlete's foot of varying severity and response to topical antibacterial and antifungal therapies.

PubMed

Talwar, P; Kumar, B; Ayyagiri, A; Kaur, S

1985-08-01

Ninety-six patients with clinical evidence of interdigital lesions classified as mild, moderate and severe athlete's foot were investigated for bacterial and fungal populations in the interspaces. Gram-negative bacteria, which were not found in the toe spaces of 50 normal controls, were grown in increasing numbers and with increasing frequency as the symptoms progressed from mild to severe. Gram-positive bacteria were also isolated regularly and in increasing numbers commensurate with the severity of the disease. Similarly the isolation rates of dermatophytes and Candida species were higher in patients with moderate and severe disease compared to those with mild disease. Clinical and culture responses to topical applications with framycetin, tolnaftate, miconazole and clotrimazole were also studied. In some patients the prevalence of pathogenic fungi increased as bacterial numbers decreased. The pure antibacterial framycetin brought symptomatic relief, as did the purely anti-dermatophyte substance tolnaftate, but best results were seen with two azole compounds having mixed antibacterial and antifungal properties.

[Post-marketing surveillance of antibacterial activities of cefozopran against various clinical isolates--II. Gram-negative bacteria].

PubMed

Igari, Jun; Oguri, Toyoko; Hiramatsu, Nobuyoshi; Akiyama, Kazumitsu; Koyama, Tsuneo

2003-10-01

As a post-marketing surveillance, the in vitro antibacterial activities of cefozopran (CZOP), an agent of cephems, against various clinical isolates were yearly evaluated and compared with those of other cephems, oxacephems, carbapenems, monobactams, and penicillins. Changes in CZOP susceptibility among bacteria were also evaluated with the bacterial resistance ratio calculated from the breakpoint MIC. Twenty-five species (4,154 strains) of Gram-negative bacteria were isolated from the clinical materials annually collected from 1996 to 2001, and consisted of Moraxella (Branhamella) catarrhalis, Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Serratia liquefaciens, Citrobacter freundii, Citrobacter koseri, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Providencia spp., Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida, Acinetobacter baumannii, Acinetobacter Iwoffii, Burkholderia cepacia, Stenotrophomonas maltophilia, Bacteroides fragilis group, and Prevotella/Porphyromonas. CZOP preserved its antibacterial activity against M. (B.) catarrhalis (MIC90: 4 micrograms/mL) and showed comparable activity to carbapenems against H. influenzae (MIC90: 1 microgram/mL). The antibacterial activity of CZOP against E. coli was preferable (MIC90: 0.125 microgram/mL) and comparable to those of cefpirome (CPR), cefepime (CFPM), and imipenem (IPM). The MIC90 of CZOP against K. pneumoniae and K. oxytoca was 1 and 0.25 microgram/mL, respectively. The MIC90 of CZOP against E. cloacae increased during 6 years (32 to 128 micrograms/mL). The antibacterial activity of CZOP against E. aerogenes was preferable (MIC90: 1 microgram/mL). The antibacterial activities of CZOP against S. marcescens and S. liquefaciens were relatively potent (MIC90: 0.5 and 0.25 microgram/mL) and comparable to those of CPR, CFPM, and carumonam. CZOP preserved comparable antibacterial activity to CPR against C. freundii and C. koseri (MIC90: 8 and 0.125 micrograms/mL). The MIC90 of CZOP against P. mirabilis, P. vulgaris, and M. morganii was 0.25, 16, and 2 micrograms/mL, respectively. The antibacterial activity of CZOP against Providencia spp. was moderate (MIC90: 64 micrograms/mL). The antibacterial activity of CZOP against P. aeruginosa was the most potent (MIC90: 16 micrograms/mL) among the test agents and comparable to those CFPM, IPM, and MEPM. CZOP had low activity against P. fluorescens and P. putida (MIC90: 128 micrograms/mL). The antibacterial activity of CZOP against A. baumannii was comparable to those of ceftazidime (CAZ), CPR and CFPM (MIC90: 32 micrograms/mL) and against A. lwoffii was moderate (MIC90: 64 micrograms/mL). Most of the test agents including CZOP had low antibacterial activity against B. cepacia, S. maltophilia, and B. fragilis group. The MIC90 of CZOP against Prevotella/Porphyromonas was 64 micrograms/mL. Bacterial cross-resistance ratio between CZOP and other agents was low in most of the species, ranging from 0.0 to 15.1%. In non-glucose fermentative bacteria, however, the bacterial cross-resistance ratio between CZOP and CFPM, CAZ, CPR, or IPM was high, being 36.8%, 28.0%, 38.7%, or 31.1%, respectively. In conclusion, the 6-year duration study suggested that the antibacterial activity of CZOP against E. cloacae possible decreased, but against other Gram-negative bacteria was consistent with the study results obtained until the new drug application approval.

Effects of water-aging for 6 months on the durability of a novel antimicrobial and protein-repellent dental bonding agent.

PubMed

Zhang, Ning; Zhang, Ke; Weir, Michael D; Xu, David J; Reynolds, Mark A; Bai, Yuxing; Xu, Hockin H K

2018-06-21

Biofilms at the tooth-restoration bonded interface can produce acids and cause recurrent caries. Recurrent caries is a primary reason for restoration failures. The objectives of this study were to synthesize a novel bioactive dental bonding agent containing dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) to inhibit biofilm formation at the tooth-restoration margin and to investigate the effects of water-aging for 6 months on the dentin bond strength and protein-repellent and antibacterial durability. A protein-repellent agent (MPC) and antibacterial agent (DMAHDM) were added to a Scotchbond multi-purpose (SBMP) primer and adhesive. Specimens were stored in water at 37 °C for 1, 30, 90, or 180 days (d). At the end of each time period, the dentin bond strength and protein-repellent and antibacterial properties were evaluated. Protein attachment onto resin specimens was measured by the micro-bicinchoninic acid approach. A dental plaque microcosm biofilm model was used to test the biofilm response. The SBMP + MPC + DMAHDM group showed no decline in dentin bond strength after water-aging for 6 months, which was significantly higher than that of the control (P < 0.05). The SBMP + MPC + DMAHDM group had protein adhesion that was only 1/20 of that of the SBMP control (P < 0.05). Incorporation of MPC and DMAHDM into SBMP provided a synergistic effect on biofilm reduction. The antibacterial effect and resistance to protein adsorption exhibited no decrease from 1 to 180 d (P > 0.1). In conclusion, a bonding agent with MPC and DMAHDM achieved a durable dentin bond strength and long-term resistance to proteins and oral bacteria. The novel dental bonding agent is promising for applications in preventive and restorative dentistry to reduce biofilm formation at the tooth-restoration margin.

Controlled release of metronidazole from composite poly-ε-caprolactone/alginate (PCL/alginate) rings for dental implants.

PubMed

Lan, Shih-Feng; Kehinde, Timilehin; Zhang, Xiangming; Khajotia, Sharukh; Schmidtke, David W; Starly, Binil

2013-06-01

Dental implants provide support for dental crowns and bridges by serving as abutments for the replacement of missing teeth. To prevent bacterial accumulation and growth at the site of implantation, solutions such as systemic antibiotics and localized delivery of bactericidal agents are often employed. The objective of this study was to demonstrate a novel method of controlled localized delivery of antibacterial agents to an implant site using a biodegradable custom fabricated ring. The study involved incorporating a model antibacterial agent (metronidazole) into custom designed poly-ε-caprolactone/alginate (PCL/alginate) composite rings to produce the intended controlled release profile. The rings can be designed to fit around the body of any root form dental implants of various diameters, shapes and sizes. In vitro release studies indicate that pure (100%) alginate rings exhibited an expected burst release of metronidazole in the first few hours, whereas Alginate/PCL composite rings produced a medium burst release followed by a sustained release for a period greater than 4 weeks. By varying the PCL/alginate weight ratios, we have shown that we can control the amount of antibacterial agents released to provide the minimal inhibitory concentration (MIC) needed for adequate protection. The fabricated composite rings have achieved a 50% antibacterial agent release profile over the first 48 h and the remaining amount slowly released over the remainder of the study period. The PCL/alginate agent release characteristic fits the Ritger-Peppas model indicating a diffusion-based mechanism during the 30-day study period. The developed system demonstrates a controllable drug release profile and the potential for the ring to inhibit bacterial biofilm growth for the prevention of diseases such as peri-implantitis resulting from bacterial infection at the implant site. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

FG90 chitosan as a new polymer for metronidazole mucoadhesive tablets for vaginal administration.

PubMed

Perioli, Luana; Ambrogi, Valeria; Pagano, Cinzia; Scuota, Stefania; Rossi, Carlo

2009-07-30

Topical administration of the antibacterial metronidazole (MET) represents the most common therapy in the treatment of bacterial vaginosis (BV). The formulations generally available for BV therapy are creams, gels, vaginal lavages and vaginal suppositories. In this study, a new dosage form, containing MET, was developed with the aim to realize vaginal mucoadhesive tablets by including bioadhesive polymers as chitosan (FG90C), polyvinylpyrrolidone (PVPK90) and polycarbophil (PCPAA1), blended in different ratios. All formulations were characterized by studies of DSC, friability, hardness, hydration, mucoadhesion, in vitro release and antibacterial activity. All polymer mixtures employed were used to prepare tablets with the compactness and hardness so as allow the application on vaginal mucosa. FG90C performances improved in particular when mixed to PVPK90 (1:1 ratio). This kind of delivery system is suitable for formulating MET for topical application representing a good alternative to traditional dosage forms for vaginal topical administration.

Graphene Oxide-Based Nanocomposites Decorated with Silver Nanoparticles as an Antibacterial Agent

NASA Astrophysics Data System (ADS)

Jaworski, Sławomir; Wierzbicki, Mateusz; Sawosz, Ewa; Jung, Anna; Gielerak, Grzegorz; Biernat, Joanna; Jaremek, Henryk; Łojkowski, Witold; Woźniak, Bartosz; Wojnarowicz, Jacek; Stobiński, Leszek; Małolepszy, Artur; Mazurkiewicz-Pawlicka, Marta; Łojkowski, Maciej; Kurantowicz, Natalia; Chwalibog, André

2018-04-01

One of the most promising methods against drug-resistant bacteria can be surface-modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO) as a novel multifunctional antibacterial and antifungal material. Ultrasonic technologies have been used as an effective method of coating polyurethane foils. Toxicity on gram-negative bacteria ( Escherichia coli), gram-positive bacteria ( Staphylococcus aureus and Staphylococcus epidermidis), and pathogenic yeast ( Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability using the PrestoBlue assay, analysis of cell membrane integrity using the lactate dehydrogenase assay, and reactive oxygen species production. Compared to Ag-NPs and GO, which have been widely used as antibacterial agents, our nanocomposite shows much higher antimicrobial efficiency toward bacteria and yeast cells.

Graphene Oxide-Based Nanocomposites Decorated with Silver Nanoparticles as an Antibacterial Agent.

PubMed

Jaworski, Sławomir; Wierzbicki, Mateusz; Sawosz, Ewa; Jung, Anna; Gielerak, Grzegorz; Biernat, Joanna; Jaremek, Henryk; Łojkowski, Witold; Woźniak, Bartosz; Wojnarowicz, Jacek; Stobiński, Leszek; Małolepszy, Artur; Mazurkiewicz-Pawlicka, Marta; Łojkowski, Maciej; Kurantowicz, Natalia; Chwalibog, André

2018-04-23

One of the most promising methods against drug-resistant bacteria can be surface-modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO) as a novel multifunctional antibacterial and antifungal material. Ultrasonic technologies have been used as an effective method of coating polyurethane foils. Toxicity on gram-negative bacteria (Escherichia coli), gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), and pathogenic yeast (Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability using the PrestoBlue assay, analysis of cell membrane integrity using the lactate dehydrogenase assay, and reactive oxygen species production. Compared to Ag-NPs and GO, which have been widely used as antibacterial agents, our nanocomposite shows much higher antimicrobial efficiency toward bacteria and yeast cells.

Antibacterial honey for the prevention of peritoneal-dialysis-related infections (HONEYPOT): a randomised trial.

PubMed

Johnson, David W; Badve, Sunil V; Pascoe, Elaine M; Beller, Elaine; Cass, Alan; Clark, Carolyn; de Zoysa, Janak; Isbel, Nicole M; McTaggart, Steven; Morrish, Alicia T; Playford, E Geoffrey; Scaria, Anish; Snelling, Paul; Vergara, Liza A; Hawley, Carmel M

2014-01-01

There is a paucity of evidence to guide the best strategy for prevention of peritoneal-dialysis-related infections. Antibacterial honey has shown promise as a novel, cheap, effective, topical prophylactic agent without inducing microbial resistance. We therefore assessed whether daily application of honey at the exit site would increase the time to peritoneal-dialysis-related infections compared with standard exit-site care plus intranasal mupirocin prophylaxis for nasal carriers of Staphylococcus aureus. In this open-label trial undertaken in 26 centres in Australia and New Zealand, participants undergoing peritoneal dialysis were randomly assigned in a 1:1 ratio with an adaptive allocation algorithm to daily topical exit-site application of antibacterial honey plus standard exit-site care or intranasal mupirocin prophylaxis (only in carriers of nasal S aureus) plus standard exit-site care (control group). The primary endpoint was time to first infection related to peritoneal dialysis (exit-site infection, tunnel infection, or peritonitis). The trial is registered with the Australian New Zealand Clinical Trials Registry, number 12607000537459. Of 371 participants, 186 were assigned to the honey group and 185 to the control group. The median peritoneal-dialysis-related infection-free survival times were not significantly different in the honey (16·0 months [IQR not estimable]) and control groups (17·7 months [not estimable]; unadjusted hazard ratio 1·12, 95% CI 0·83-1·51; p=0·47). In the subgroup analyses, honey increased the risks of both the primary endpoint (1·85, 1·05-3·24; p=0·03) and peritonitis (2·25, 1·16-4·36) in participants with diabetes. The incidences of serious adverse events (298 vs 327, respectively; p=0·1) and deaths (14 vs 18, respectively; p=0·9) were not significantly different in the honey and control groups. 11 (6%) participants in the honey group had local skin reactions. The findings of this trial show that honey cannot be recommended routinely for the prevention of peritoneal-dialysis-related infections. Baxter Healthcare, Queensland Government, Comvita, and Gambro. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of Antibacterial Activity of Three Selected Fruit Juices on Clinical Endodontic Bacterial Strains

PubMed Central

Behera, Subasish; Khetrapal, Prashant; Punia, Sandhya Kapoor; Agrawal, Deepak; Khandelwal, Minal; Lohar, Jitendra

2017-01-01

Introduction: The increasing problem of antibiotic drug resistance by pathogenic microorganisms in the past few decades has recently led to the continuous exploration of natural plant products for new antibiotic agents. Many consumable food materials have good as well as their bad effects, good effect includes their antibacterial effects on different microorganisms present in the oral cavity. Recently, natural products have been evaluated as source of antimicrobial agent with efficacies against a variety of microorganisms. Methodology: The present study describes the antibacterial activity of three selected fruit juices (Apple, Pomegranate and Grape) on endodontic bacterial strains. Antimicrobial activity of fruit juices were tested by wel l diffusion assay by an inhibition zone surrounding the well. The aim of the study was to evaluate the antibacterial activity of three fruit juises on different endodontic strains. Result: Agar well diffusion method was adopted for determining antibacterial potency. Antibacterial activity present on the plates was indicated by an inhibition zone surrounding the well containing the fruit juice. The zone of inhibition was measured by measuring scale in millimeter. Comparision between antibacterial efficacy of all three fruit juices against Enterococcus feacalis and Streptococcus mutans was observed with significant value of P ≤ 0.05. Conclusion: The results obtained in this study clearly demonstrated a significant antimicrobial effect of apple fruit juice against Enterococcus fecalis and Streptococcus mutans. However, preclinical and clinical trials are needed to evaluate biocompatibility & safety before apple can conclusively be recommended in endodontic therapy, but in vitro observation of apple effectiveness appears promising. PMID:29284967

Consumption of antibacterial molecules in broiler production in Morocco.

PubMed

Rahmatallah, Naoufal; El Rhaffouli, Hicham; Lahlou Amine, Idriss; Sekhsokh, Yassine; Fassi Fihri, Ouafaa; El Houadfi, Mohammed

2018-05-01

Monitoring the use of antibacterial agents in food-producing animals is crucial in order to reduce antimicrobial resistance, selection and dissemination of resistant bacterial strains, and drug residues in the animal food products. The broiler production sector is considered a great consumer of antibacterials and incriminated in the rise of antimicrobial resistance level in zoonotic bacterial pathogens such as Escherichia coli, Salmonella and Campylobacter. Following recommendations from the OIE and WHO, a survey was conducted about the use and consumption of several antibacterial agents in Moroccan broiler flocks. More than 5 million broilers were randomly surveyed at the prescriber level, that is, via the veterinary clinics involved in their health management. The results showed that 93% of the flocks received at least one antibacterial treatment of minimum 3 days duration. Enrofloxacin, colistin and trimethoprim/sulphonamides were the most used antibacterials followed by oxytetracycline, florfenicol and amoxicillin. Oxytetracycline, enrofloxacin and colistin were overdosed in most of the administration, while amoxicillin and the combination of trimethoprim/sulphonamides were under-dosed. The total amount of antibacterial consumed in the survey was 63.48 mg/kg and the Animal Level of Exposure to Antimicrobials (ALEA) was 94.45%. The reasons for this frequent use were related mainly to the poor quality of broiler production management. Chicks and animal feed provided to producers were of variable quality. Management of rearing stock density was often poor and biosecurity inadequate, and broilers were challenged by a high prevalence of infectious diseases. © 2018 The Authors. Veterinary Medicine and Science Published by John Wiley & Sons Ltd.

Vibrio sp. DSM 14379 pigment production--a competitive advantage in the environment?

PubMed

Starič, Nejc; Danevčič, Tjaša; Stopar, David

2010-10-01

The ability to produce several antibacterial agents greatly increases the chance of producer's survival. In this study, red-pigmented Vibrio sp. DSM 14379 and Bacillus sp., both isolated from the same sampling volume from estuarine waters of the Northern Adriatic Sea, were grown in a co-culture. The antibacterial activity of the red pigment extract was tested on Bacillus sp. in microtiter plates. The MIC(50) for Bacillus sp. was estimated to be around 10⁻⁵ mg/L. The extract prepared form the nonpigmented mutant of Vibrio sp. had no antibacterial effect. The pigment production of Vibrio sp. was studied under different physicochemical conditions. There was no pigment production at high or low temperatures, high or low salt concentrations in peptone yeast extract (PYE) medium, low glucose concentration in mineral growth medium or high glucose concentration in PYE medium. This indicates that the red pigment production is a luxurious good that Vibrio sp. makes only under favorable conditions. The Malthusian fitness of Bacillus sp. in a co-culture with Vibrio sp. under optimal environmental conditions dropped from 4.0 to -7.6, which corresponds to three orders of magnitude decrease in the number of CFU relative to the monoculture. The nonpigmented mutant of Vibrio sp. in a co-culture with Bacillus sp. had a significant antibacterial activity. This result shows that studying antibacterial properties in isolation (i.e. pigment extract only) may not reveal full antibacterial potential of the bacterial strain. The red pigment is a redundant antibacterial agent of Vibrio sp.

Colloidal silver nanoparticles/rhamnolipid (SNPRL) composite as novel chemotactic antibacterial agent.

PubMed

Bharali, P; Saikia, J P; Paul, S; Konwar, B K

2013-10-01

The antibacterial activity of silver nanoparticles and rhamnolipid are well known individually. In the present research, antibacterial and chemotactic activity due to colloidal silver nanoparticles (SNP), rhamnolipid (RL) and silver nanoparticles/rhamnolipid composite (SNPRL) were evaluated using Staphylococcus aureus (MTCC3160), Escherichia coli (MTCC40), Pseudomonas aeruginosa (MTCC8163) and Bacillus subtilis (MTCC441) as test strains. Further, the SNPRL nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The observation clearly indicates that SNPRL shows prominent antibacterial and chemotactic activity in comparison to all of its individual precursor components. Copyright © 2013 Elsevier B.V. All rights reserved.

[Acute tonsillopharyngitis: the effectiveness of topical therapy].

PubMed

Nosulya, E V; Kim, I A; Chernykh, N M; Karnoukhova, O A

2015-01-01

The objective of the present study was to evaluate the clinical effectiveness of a furasol sore throat gargle solution for the treatment of acute tonsillopharyngitis. Forty patients presenting with acute tonsillopharyngitis were allocated to two groups, 20 subjects in each, by means of independent sequential randomization. Prior to the onset of the treatment, all the patients were examined for determining the species composition of pharyngeal microflora with the use of an «AutoScan4 System» analyzer («Siemens», USA) and estimating the resistance to antibacterial preparations (by the disk diffusion method). All the participants of the study were prescribed antibacterial therapy. In the patients of group 1 (study group), the antibacterial treatment of acute tonsillopharyngitis was supplemented by a furasol sore throat gargle solution whereas those of group 2 (controls) were treated without topical therapy. The quantitative evaluation of the severity of manifestations of the disease before and after the treatment was based on a 5-point visual-analog scale. It was shown that systemic antibacterial therapy resulted in the consistent decrease of the frequency of occurrence of pathogenic and potentially pathogenic microflora in the patients comprising both groups. Treatment with a furasol sore throat gargle solution did not lead to the appearance of bacterial species alien to the oropharynx, nor was it accompanied by the impairment of resistance of its mucous membrane to the colonization by microorganisms. The results of the study give evidence of the well apparent regression of the subjective signs of tonsillopharyngitis and the inflammatory changes in the mucous membrane of the pharynx in the patients given the topical treatment in the form of a furasol sore throat gargle solution in addition to antibacterial therapy. It is concluded that a furasol sore throat gargle solution can be recommended for the introduction into the combined treatment of the patients presenting with acute tonsillopharyngitis.

Modulation of the multidrug efflux pump EmrD-3 from Vibrio cholerae by Allium sativum extract and the bioactive agent allyl sulfide plus synergistic enhancement of antimicrobial susceptibility by A. sativum extract.

PubMed

Bruns, Merissa M; Kakarla, Prathusha; Floyd, Jared T; Mukherjee, Mun Mun; Ponce, Robert C; Garcia, John A; Ranaweera, Indrika; Sanford, Leslie M; Hernandez, Alberto J; Willmon, T Mark; Tolson, Grace L; Varela, Manuel F

2017-10-01

The causative agent of cholera, Vibrio cholerae, is a public health concern. Multidrug-resistant V. cholerae variants may reduce chemotherapeutic efficacies of severe cholera. We previously reported that the multidrug efflux pump EmrD-3 from V. cholerae confers resistance to multiple structurally distinct antimicrobials. Medicinal plant compounds are potential candidates for EmrD-3 efflux pump modulation. The antibacterial activities of garlic Allium sativum, although poorly understood, predicts that a main bioactive component, allyl sulfide, modulates EmrD-3 efflux. Thus, we tested whether A. sativum extract acts in synergy with antimicrobials and that a main bioactive component allyl sulfide inhibits EmrD-3 efflux. We found that A. sativum extract and allyl sulfide inhibited ethidium bromide efflux in cells harboring EmrD-3 and that A. sativum lowered the MICs of multiple antibacterials. We conclude that A. sativum and allyl sulfide inhibit EmrD-3 and that A. sativum extract synergistically enhances antibacterial agents.

Marine sponge alkaloids as a source of anti-bacterial adjuvants

PubMed Central

Melander, Roberta J.; Liu, Hong-bing; Stephens, Matthew D.; Bewley, Carole A.; Melander, Christian

2018-01-01

Novel approaches that do not rely upon developing microbicidal compounds are sorely needed to combat multidrug resistant (MDR) bacteria. The potential of marine secondary metabolites to serve as a source of non-traditional anti-bacterial agents is demonstrated by showing that pyrrole-imidazole alkaloids inhibit biofilm formation and suppress antibiotic resistance. PMID:27876320

Pain control in a randomized, controlled, clinical trial comparing moist exposed burn ointment and conventional methods in patients with partial-thickness burns.

PubMed

Ang, Erik; Lee, S-T; Gan, Christine S-G; Chan, Y-H; Cheung, Y-B; Machin, D

2003-01-01

Conventional management of partial-thickness burn wounds includes the use of paraffin gauze dressing, frequently with topical silver-based antibacterial creams. Some creams form an overlying slough that renders wound assessment difficult and are painful upon application. An alternative to conventional management, moist exposed burn ointment (MEBO), has been proposed as a topical agent that may accelerate wound healing and have antibacterial and analgesic properties. One hundred fifteen patients with partial-thickness burns were randomly assigned to conventional (n = 58) or MEBO treatment (n = 57). A verbal numerical rating score of pain was made in the morning, after burn dressing, and some 8 hours later. Patient pain profiles were summarized by locally weighted regression smoothing technique curves and the difference between treatments estimated using multilevel regression techniques. Mean verbal numerical rating scale pain levels (cm) in week 1 for all patients were highest at 3.2 for the after dressing assessment, lowest in the evening at 2.6, and intermediate in the morning at 3.0. This pattern continued at similar levels in week 2 and then declined by a mean of 0.5 in all groups in week 3. There was little evidence to suggest a difference in pain levels by treatment group with the exception of the postdressing pain levels in the first week when those receiving MEBO had a mean level of 0.7 cm (95% confidence interval, 0.2 to 1.1) lower than those on conventional therapy. MEBO appeared to bring greater pain relief for the postdressing assessment during the first week after burns. This initial relief, together with comparable pain levels experienced on other occasions, indicates that MEBO could be an alternative to conventional burns management.

Fabrication of silver nanoparticle sponge leather with durable antibacterial property.

PubMed

Liu, Gongyan; Haiqi, Gao; Li, Kaijun; Xiang, Jun; Lan, Tianxiang; Zhang, Zongcai

2018-03-15

Leather product with durable antibacterial property is of great interest both from industry and consumer's point of view. To fabricate such functional leather, gallic acid modified silver nanoparticles (GA@AgNPs) were first in situ synthesized with a core-shell structure and an average size of 15.3nm. Due to its hydrophilic gallic acid surface, the GA@AgNPs possessed excellent stability and dispersibility in wide pH range from 3 to 12 and also showed effective antibacterial activity with a minimum inhibitory concentration (MIC) of around 10μgmL -1 . Then, such GA@AgNPs were used as retanning agent to be successfully filled into leather matrix during the leather manufacturing process. Moreover, taking the advantage of its high surface density of carboxyl groups, these GA@AgNPs could be further chemically cross-linked onto collagen fibers by chrome tanning agent. After retanning, the resultant leather was given a "AgNPs sponge" feature with high payload of silver nanoparticles against laundry, exhibiting high and durable antibacterial activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Identification of linoleic acid, a main component of the n-hexane fraction from Dryopteris crassirhizoma, as an anti-Streptococcus mutans biofilm agent.

PubMed

Jung, Ji-Eun; Pandit, Santosh; Jeon, Jae-Gyu

2014-01-01

Dryopteris crassirhizoma is a semi-evergreen plant. Previous studies have shown the potential of this plant as an agent for the control of cariogenic biofilms. In this study, the main antibacterial components of the plant were identified by correlating gas chromatography-mass spectrometry data with the antibacterial activity of chloroform and n-hexane fractions and then evaluating the activity of the most potent antibacterial component against Streptococcus mutans UA159 biofilms. The most potent antibacterial component was linoleic acid, a main component of the n-hexane fraction. Linoleic acid reduced viability in a dose dependent manner and reduced biofilm accumulation during initial and mature biofilm formation. Furthermore, when the biofilms were briefly treated with linoleic acid (10 min/treatment, a total of six times), the dry weight of the biofilms was significantly diminished. In addition, the anti-biofilm activity of the n-hexane fraction was similar to that of linoleic acid. These results suggest that the n-hexane fraction of D. crassirhizoma and linoleic acid may be useful for controlling cariogenic biofilms.

Study on antibacterial activity of silver nanoparticles synthesized by gamma irradiation method using different stabilizers

NASA Astrophysics Data System (ADS)

Van Phu, Dang; Quoc, Le Anh; Duy, Nguyen Ngoc; Lan, Nguyen Thi Kim; Du, Bui Duy; Luan, Le Quang; Hien, Nguyen Quoc

2014-04-01

Colloidal solutions of silver nanoparticles (AgNPs) were synthesized by gamma Co-60 irradiation using different stabilizers, namely polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), alginate, and sericin. The particle size measured from TEM images was 4.3, 6.1, 7.6, and 10.2 nm for AgNPs/PVP, AgNPs/PVA, AgNPs/alginate, and AgNPs/sericin, respectively. The influence of different stabilizers on the antibacterial activity of AgNPs was investigated. Results showed that AgNPs/alginate exhibited the highest antibacterial activity against Escherichia coli ( E. coli) among the as-synthesized AgNPs. Handwash solution has been prepared using Na lauryl sulfate as surfactant, hydroxyethyl cellulose as binder, and 15 mg/L of AgNPs/alginate as antimicrobial agent. The obtained results on the antibacterial test of handwash for the dilution to 3 mg AgNPs/L showed that the antibacterial efficiency against E. coli was of 74.6%, 89.8%, and 99.0% for the contacted time of 1, 3, and 5 min, respectively. Thus, due to the biocompatibility of alginate extracted from seaweed and highly antimicrobial activity of AgNPs synthesized by gamma Co-60 irradiation, AgNPs/alginate is promising to use as an antimicrobial agent in biomedicine, cosmetic, and in other fields.

The Mechanism Underlying the Antibacterial Activity of Shikonin against Methicillin-Resistant Staphylococcus aureus

PubMed Central

Lee, Dae-Young; Kim, Yeon Bok; Lee, Sang-Won; Cha, Seon-Woo; Park, Hong-Woo; Kim, Geum-Soog; Kwon, Dong-Yeul; Lee, Min-Ho; Han, Sin-Hee

2015-01-01

Shikonin (SKN), a highly liposoluble naphthoquinone pigment isolated from the roots of Lithospermum erythrorhizon, is known to exert antibacterial, wound-healing, anti-inflammatory, antithrombotic, and antitumor effects. The aim of this study was to examine SKN antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The SKN was analyzed in combination with membrane-permeabilizing agents Tris and Triton X-100, ATPase inhibitors sodium azide and N,N′-dicyclohexylcarbodiimide, and S. aureus-derived peptidoglycan; the effects on MRSA viability were evaluated by the broth microdilution method, time-kill test, and transmission electron microscopy. Addition of membrane-permeabilizing agents or ATPase inhibitors together with a low dose of SKN potentiated SKN anti-MRSA activity, as evidenced by the reduction of MRSA cell density by 75% compared to that observed when SKN was used alone; in contrast, addition of peptidoglycan blocked the antibacterial activity of SKN. The results indicate that the anti-MRSA effect of SKN is associated with its affinity to peptidoglycan, the permeability of the cytoplasmic membrane, and the activity of ATP-binding cassette (ABC) transporters. This study revealed the potential of SKN as an effective natural antibiotic and of its possible use to substantially reduce the use of existing antibiotic may also be important for understanding the mechanism underlying the antibacterial activity of natural compounds. PMID:26265924

Selective antibacterial effects of mixed ZnMgO nanoparticles

NASA Astrophysics Data System (ADS)

Vidic, Jasmina; Stankic, Slavica; Haque, Francia; Ciric, Danica; Le Goffic, Ronan; Vidy, Aurore; Jupille, Jacques; Delmas, Bernard

2013-05-01

Antibiotic resistance has impelled the research for new agents that can inhibit bacterial growth without showing cytotoxic effects on humans and other species. We describe the synthesis and physicochemical characterization of nanostructured ZnMgO whose antibacterial activity was compared to its pure nano-ZnO and nano-MgO counterparts. Among the three oxides, ZnO nanocrystals—with the length of tetrapod legs about 100 nm and the diameter about 10 nm—were found to be the most effective antibacterial agents since both Gram-positive ( B. subtilis) and Gram-negative ( E. coli) bacteria were completely eradicated at concentration of 1 mg/mL. MgO nanocubes (the mean cube size 50 nm) only partially inhibited bacterial growth, whereas ZnMgO nanoparticles (sizes corresponding to pure particles) revealed high specific antibacterial activity to Gram-positive bacteria at this concentration. Transmission electron microscopy analysis showed that B. subtilis cells were damaged after contact with nano-ZnMgO, causing cell contents to leak out. Our preliminary toxicological study pointed out that nano-ZnO is toxic when applied to human HeLa cells, while nano-MgO and the mixed oxide did not induce any cell damage. Overall, our results suggested that nanostructured ZnMgO, may reconcile efficient antibacterial efficiency while being a safe new therapeutic for bacterial infections.

Sodium alginate/carboxymethyl cellulose films containing pyrogallic acid: physical and antibacterial properties.

PubMed

Han, Yingying; Wang, Lijuan

2017-03-01

Antibacterial films were prepared using sodium alginate (SA) and carboxymethyl cellulose (CMC) as a matrix, glycerin as a plasticizer and CaCl 2 as a cross-linking agent, and by incorporating the natural antibacterial agent pyrogallic acid (PA). The present study describes the microstructure and the physical, barrier, mechanical, optical and antibacterial properties of blended films prepared by incorporating different concentrations of PA into the SA/CMC matrix. The microstructure of the films was investigated by Fourier transform infrared spectroscopy and scanning electron microscopy, which revealed that PA interacts with the SA/CMC matrix through hydrogen bonding. Moreover, the incorporation of PA increased the moisture content, water vapor permeability and oxygen permeability of SA/CMC films. Films containing 40 g kg -1 of PA had the highest elongation at break result (39.60%). Compared with pure SA/CMC films, the incorporation of PA improved the barrier properties against ultraviolet light; however, it decreased the color parameter L* value and increased the a* and b* values of the films. Furthermore, films with PA, especially at higher concentrations, were more effective against Escherichia coli and Staphylococcus aureus. Antibacterial SA/CMC films incorporating PA appear to have good potential to enhance the safety of foods and food products. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Screening Antibacterial Agent from Crude Extract of Marine-Derived Fungi Associated with Soft Corals against MDR-Staphylococcus haemolyticus

NASA Astrophysics Data System (ADS)

Sabdaningsih, A.; Cristianawati, O.; Sibero, M. T.; Nuryadi, H.; Radjasa, O. K.; Sabdono, A.; Trianto, A.

2017-02-01

Multidrug resistant Staphylococcus haemolyticus is a Gram-positive bacteria and member of coagulase negative staphylococci (CoNS) which has the highest level of antimicrobial resistance. This nosocomial pathogen due to skin or soft tissue infections, bacteremia, septicemia, peritonitis, otitis media, meningitis and urinary tract infections. The ability to produce enterotoxins, hemolysins, biofilm, and cytotoxins could be an important characteristic for the successful of infection. Marine-derived fungi have potency as a continuous supply of bioactive compound. The aim of this research was screening antibacterial agent from crude extracts of marine-derived fungi associated with soft corals against MDR-S. haemolyticus. Among 23 isolates of marine-derived fungi isolated from 7 soft corals, there were 4 isolates active against MDR-S. haemolyticus. The screening was conducted by using agar plug diffusion method. Isolate PPSC-27-A4 had the highest antibacterial activity with diameter 23±9,6 mm. The crude extract from this isolate had been confirmed to antibacterial susceptibility test and it had the highest antibacterial activity in 12.2 mm with concentration of 300μg/ml from mycelia extract. PPSC-27-A4 had been characterized in molecular, based on the sequence analysis of 18S rRNA, PPSC-27-A4 isolate was identified as Trichoderma longibrachiatum.

Timber industry waste-teak ( Tectona grandis Linn.) leaf extract mediated synthesis of antibacterial silver nanoparticles

NASA Astrophysics Data System (ADS)

Devadiga, Aishwarya; Shetty, K. Vidya; Saidutta, M. B.

2015-08-01

The current research article emphasizes efficacious use of teak leaves, an agro -biowaste from world's premier hardwood timber industry, for "green" synthesis of silver nanoparticles (AgNPs). Bioactive compounds of the leaves act as prolific reducing and stabilizing agents in AgNP synthesis. The characterization of the AgNPs synthesized using teak leaves revealed that the particles are spherical with an average size of 28 nm and the presence of bioactive compounds present in teak leaf extract as capping agents on the nanoparticles. A prominent decrease in the content of bioactive compounds such as polyphenols, antioxidants and flavonoids after the biosynthesis of AgNPs signifies that these class of compounds act as reductants and stabilizers during biosynthesis. The biosynthesized silver nanoparticles were also successfully evaluated for their antibacterial characteristics against waterborne pathogens, E. coli and S. aureus, with minimum inhibitory concentration of 25.6 μg/mL. Exploitation of agrowaste resources for synthesis of AgNPs curtails indiscriminate usage of food and commercial plant materials, rather contributing a sustainable way for effective plant waste biomass utilization and management. The biosynthesized AgNps have potential application in water purifiers, antibacterial fabrics, sports wear and in cosmetics as antibacterial agent and the process used for its synthesis being greener is highly beneficial from environmental, energy consumption and economic perspectives.

Design and Evaluation of Microemulsion Gel System of Nadifloxacin

PubMed Central

Shinde, Ujwala; Pokharkar, Sharda; Modani, Sheela

2012-01-01

Topical microemulsion systems for the antiacne agent, nadifloxacin were designed and developed to overcome the problems associated with the cutaneous delivery due to poor water solubility. The solubility of nadifloxacin in oils, surfactants and cosurfactants was evaluated to screen the components of the microemulsion. Various surfactants and cosurfactants were screened for their ability to emulsify the selected oily phase. The pseudoternary diagrams were constructed to identify the area of microemulsion existence. The influence of km (surfactant/cosurfactant) ratio on the microemulsion existence region was determined and optimum systems were designed. The systems were assessed for drug-loading efficiency and characterised for optical birefringence, pH and refractive index, robustness to dilution, globule size, drug content and thermodynamic stability. Optimised microemulsion systems were formulated into gel form and evaluated for viscosity, spreadability, drug content, ex vivo skin permeation and antibacterial activity. The maximum solubility of nadifloxacin in the microemulsion system was found to be 0.25%. The nadifloxacin microemulsions had a small and uniform globule size (67.3-121.23 nm). The stability results revealed that all formulations showed a stable globule size and the polydispersity index under stress conditions. Incorporation of nadifloxacin in microemulsion gel increased the ex vivo skin permeation and antibacterial activity when compared to marketed cream. PMID:23439454

Effect of Two Cancer Chemotherapeutic Agents on the Antibacterial Activity of Three Antimicrobial Agents

PubMed Central

Moody, Marcia R.; Morris, Maureen J.; Young, Viola Mae; Moyé, Lemuel A.; Schimpff, Stephen C.; Wiernik, Peter H.

1978-01-01

Cancer chemotherapeutic agents and antibacterial antibiotics are often given concomitantly. Daunorubicin, cytosine arabinoside, and three antibiotics (gentamicin, amikacin, and ticarcillin) were tested individually and in combinations to determine their antimicrobial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli. These cytotoxic agents are commonly employed in the therapy of acute nonlymphocytic leukemia for remission induction therapy, and these antimicrobial agents are used in infection therapy. The maximum concentrations of the two cytotoxic drugs were chosen to be twice the known peak plasma levels of commonly employed dosage schedules. Neither of the cancer chemotherapeutic agents, alone or in combination, demonstrated bactericidal activity at the levels tested. However, in the presence of these agents, the antimicrobial activity of gentamicin and amikacin, although not that of ticarcillin, was depressed for 11 of 15 K. pneumoniae strains and 8 of 15 P. aeruginosa strains, but for none of the strains of E. coli. This level of decreased activity occasionally resulted in a minimal inhibitory concentration of the tested aminoglycoside well above the standard serum levels. Daunorubicin was more likely to antagonize gentamicin than was cytosine arabinoside. PMID:103494

Antibacterial screening of traditional herbal plants and standard antibiotics against some human bacterial pathogens.

PubMed

Awan, Uzma Azeem; Andleeb, Saiqa; Kiyani, Ayesha; Zafar, Atiya; Shafique, Irsa; Riaz, Nazia; Azhar, Muhammad Tehseen; Uddin, Hafeez

2013-11-01

Chloroformic and isoamyl alcohol extracts of Cinnnamomum zylanicum, Cuminum cyminum, Curcuma long Linn, Trachyspermum ammi and selected standard antibiotics were investigated for their in vitro antibacterial activity against six human bacterial pathogens. The antibacterial activity was evaluated and based on the zone of inhibition using agar disc diffusion method. The tested bacterial strains were Streptococcus pyogenes, Staphylococcus epidermidis, Klebsiella pneumonia, Staphylococcus aurues, Serratia marcesnces, and Pseudomonas aeruginosa. Ciprofloxacin showed highly significant action against K. pneumonia and S. epidermidis while Ampicillin and Amoxicillin indicated lowest antibacterial activity against tested pathogens. Among the plants chloroform and isoamyl alcohol extracts of C. cyminum, S. aromaticum and C. long Linn had significant effect against P. aeruginosa, S. marcesnces and S. pyogenes. Comparison of antibacterial activity of medicinal herbs and standard antibiotics was also recorded via activity index. Used medicinal plants have various phytochemicals which reasonably justify their use as antibacterial agent.

[Yearly changes in antibacterial activities of cefozopran against various clinical isolates between 1996 and 2000--I. Gram-positive bacteria].

PubMed

Suzuki, Yumiko; Nishinari, Chisato; Endo, Harumi; Tamura, Chieko; Jinbo, Keiko; Hiramatsu, Nobuyoshi; Akiyama, Kazumitsu; Koyama, Tsuneo

2002-04-01

The in vitro antibacterial activities of cefozopran (CZOP), an agent of cephems, against various clinical isolates obtained between 1996 and 2000 were yearly evaluated and compared with those of other cephems, oxacephems, carbapenems, and penicillins. Fifteen species, 1,062 strains, of Gram-positive bacteria were isolated from the clinical materials annually collected from January to December, and consisted of methicillin-susceptible Staphylococcus aureus (MSSA; n = 127), methicillin-resistant Staphylococcus aureus (MRSA; n = 123), Staphylococcus epidermidis (n = 104), Staphylococcus haemolyticus (n = 58), Streptococcus pyogenes (n = 100), Streptococcus agalactiae (n = 50), Streptococcus pneumoniae (n = 125), Enterococcus faecalis (n = 150), Enterococcus faecium (n = 50), Enterococcus avium (n = 50), and Peptostreptococcus spp. (P. anaerobius, P. asaccharolyticus, P. magnus, P. micros, P. prevotii; n = 125). CZOP possessed stable antibacterial activities against all strains tested throughout 5 years. The MIC90 of CZOP against MRSA and S. haemolyticus tended to decrease while against S. pneumoniae and Peptostreptococcus spp., tended to increase year by year. However, the MIC90 just changed a little and were consistent with the results from the studies performed until the new drug application approval. Increases in the MIC90 against S. pneumoniae were also observed with cefpirome (CPR), cefepime (CFPM), flomoxef (FMOX), sulbactam/cefoperazone (SBT/CPZ), and imipenem (IPM). Increases in the MIC90 against Peptostreptococcus spp. were also observed with ceftazidime (CAZ), CPR, CFPM, FMOX, SBT/CPZ, and IPM. The decreases in the sensitivities were not always considered to depend upon generation of resistant bacteria because the annual MIC range of each antibacterial agent was almost generally wide every year and the annual sensitivity of each strain to the agents extremely varied. In conclusion, the annual antibacterial activities of CZOP against the Gram-positive bacteria did not considerably change. It, therefore, was suggested that CZOP had maintained high antibacterial activity during 5 years of post-marketing.

pH-activated Nanoparticles for Controlled Topical Delivery of Farnesol to Disrupt Oral Biofilm Virulence

PubMed Central

Horev, Benjamin; Klein, Marlise I.; Hwang, Geelsu; Li, Yong; Kim, Dongyeop; Koo, Hyun; Benoit, Danielle S.W.

2015-01-01

Development of effective therapies to control oral biofilms is challenging, as topically introduced agents must avoid rapid clearance from biofilm-tooth interfaces while targeting biofilm microenvironments. Additionally, exopolysaccharide matrix and acidification of biofilm microenvironments are associated with cariogenic (caries-producing) biofilm virulence. Thus, nanoparticle carriers capable of binding to hydroxyapatite (HA), saliva-coated HA (sHA), and exopolysaccharides with enhanced drug-release at acidic pH were developed. Nanoparticles are formed from diblock copolymers composed of 2-(dimethylamino)ethyl methacrylate (DMAEMA), butyl methacrylate (BMA), and 2-propylacrylic acid (PAA) (p(DMAEMA)-b-p(DMAEMA-co-BMA-co-PAA)) that self-assemble into ~21 nm cationic nanoparticles. Nanoparticles exhibit outstanding adsorption affinities (~244 L-mmol−1) to negatively-charged HA, sHA, and exopolysaccharide-coated sHA due to strong electrostatic interactions via multivalent tertiary amines of p(DMAEMA). Owing to hydrophobic cores, Nanoparticles load farnesol, a hydrophobic antibacterial drug, at ~22 wt%. Farnesol release is pH-dependent with t1/2=7 and 15 h for release at pH 4.5 and 7.2, as Nanoparticles undergo core destabilization at acidic pH, characteristic of cariogenic biofilm microenvironments. Importantly, topical applications of farnesol-loaded nanoparticles disrupted Streptococcus mutans biofilms 4-fold more effectively than free farnesol. Mechanical stability of biofilms treated with drug-loaded nanoparticles was compromised, resulting in >2-fold enhancement in biofilm removal under shear stress compared to free farnesol and controls. Farnesol-loaded nanoparticles effectively attenuated biofilm virulence in vivo using a clinically-relevant topical treatment regimen (2×/day) in a rodent dental caries disease model. Treatment with farnesol-loaded nanoparticles reduced both the number and severity of carious lesions, while free-farnesol had no effect. Nanoparticles have great potential to enhance the efficacy of antibiofilm agents through multi-targeted binding and pH-responsive drug release due to microenvironmental triggers. PMID:25661192

Investigation of antibacterial mode of action for traditional and amphiphilic aminoglycosides.

PubMed

Udumula, Venkatareddy; Ham, Young Wan; Fosso, Marina Y; Chan, Ka Yee; Rai, Ravi; Zhang, Jianjun; Li, Jie; Chang, Cheng-Wei Tom

2013-03-15

Aminoglycoside represents a class of versatile and broad spectrum antibacterial agents. In an effort to revive the antibacterial activity against aminoglycoside resistant bacteria, our laboratory has developed two new classes of aminoglycoside, pyranmycin and amphiphilic neomycin (NEOF004). The former resembles the traditional aminoglycoside, neomycin. The latter, albeit derived from neomycin, appears to exert antibacterial action via a different mode of action. In order to discern that these aminoglycoside derivatives have distinct antibacterial mode of action, RNA-binding affinity and fluorogenic dye were employed. These studies, together with our previous investigation, confirm that pyranmycin exhibit the traditional antibacterial mode of action of aminoglycosides by binding toward the bacterial rRNA. On the other hand, the amphiphilic neomycin, NEOF004 disrupts the bacterial cell wall. In a broader perspective, it verifies that structurally modified neomycin can exert different antibacterial mode of action leading to the revival of activity against aminoglycoside resistant bacteria. Copyright © 2013 Elsevier Ltd. All rights reserved.

Size-dependent bacterial growth inhibition and mechanism of antibacterial activity of zinc oxide nanoparticles.

PubMed

Raghupathi, Krishna R; Koodali, Ranjit T; Manna, Adhar C

2011-04-05

The antibacterial properties of zinc oxide nanoparticles were investigated using both gram-positive and gram-negative microorganisms. These studies demonstrate that ZnO nanoparticles have a wide range of antibacterial activities toward various microorganisms that are commonly found in environmental settings. The antibacterial activity of the ZnO nanoparticles was inversely proportional to the size of the nanoparticles in S. aureus. Surprisingly, the antibacterial activity did not require specific UV activation using artificial lamps, rather activation was achieved under ambient lighting conditions. Northern analyses of various reactive oxygen species (ROS) specific genes and confocal microscopy suggest that the antibacterial activity of ZnO nanoparticles might involve both the production of reactive oxygen species and the accumulation of nanoparticles in the cytoplasm or on the outer membranes. Overall, the experimental results suggest that ZnO nanoparticles could be developed as antibacterial agents against a wide range of microorganisms to control and prevent the spreading and persistence of bacterial infections.

Antibacterial potential of Calotropis procera (flower) extract against various pathogens.

PubMed

Ali, Abid; Ansari, Asma; Qader, Shah Ali Ul; Mumtaz, Majid; Saied, Sumayya; Mahboob, Tabassum

2014-09-01

Increased bacterial resistance towards commonly used antibiotics has become a debated issue all over the world in a last few decades. Due to this, consumer demand towards natural anti-microbial agents is increasing day by day. Natural anti-microbial agents have gained enormous attention as an alternative therapeutic agent in pharmaceutical industry. Current study is an effort to explore and identify a bactericidal potential of various solvent extracts of Calotropis procera flower. Flowers of C. procera were extracted with hexane, butanol, ethyl acetate and aqua to evaluate the antibacterial activity by agar well diffusion method against the various human pathogens. The microorganisms used in this study includes Salmonella typhi, Escherichia coli (O157:H7), Micrococcus luteus KIBGE-IB20 (Gen Bank accession: JQ250612) and methicillin resistant Staphylococcus aureus (MRSA) KIBGE-IB23 (Gen Bank accession: KC465400). Zones of inhibition were observed against all four pathogenic strains. Fraction soluble in hexane showed broad spectrum of inhibition against all the studied pathogens. However, fractions soluble in ethyl acetate inhibited the growth of E. coli, MRSA, and M. luteus. In case of butanol and aqueous extracts only growth of M. luteus was inhibited. Results revealed that the flower extracts of C. procera have a potential to be used as an antibacterial agent against these pathogenic organisms.

Revitalizing the drug pipeline: AntibioticDB, an open access database to aid antibacterial research and development.

PubMed

Farrell, L J; Lo, R; Wanford, J J; Jenkins, A; Maxwell, A; Piddock, L J V

2018-06-11

The current state of antibiotic discovery, research and development is insufficient to respond to the need for new treatments for drug-resistant bacterial infections. The process has changed over the last decade, with most new agents that are in Phases 1-3, or recently approved, having been discovered in small- and medium-sized enterprises or academia. These agents have then been licensed or sold to large companies for further development with the goal of taking them to market. However, early drug discovery and development, including the possibility of developing previously discontinued agents, would benefit from a database of antibacterial compounds for scrutiny by the developers. This article describes the first free, open-access searchable database of antibacterial compounds, including discontinued agents, drugs under pre-clinical development and those in clinical trials: AntibioticDB (AntibioticDB.com). Data were obtained from publicly available sources. This article summarizes the compounds and drugs in AntibioticDB, including their drug class, mode of action, development status and propensity to select drug-resistant bacteria. AntibioticDB includes compounds currently in pre-clinical development and 834 that have been discontinued and that reached varying stages of development. These may serve as starting points for future research and development.

Foodborne Pathogens Prevention and Sensory Attributes Enhancement in Processed Cheese via Flavoring with Plant Extracts.

PubMed

Tayel, Ahmed A; Hussein, Heba; Sorour, Noha M; El-Tras, Wael F

2015-12-01

Cheese contaminations with foodborne bacterial pathogens, and their health outbreaks, are serious worldwide problems that could happen from diverse sources during cheese production or storage. Plants, and their derivatives, were always regarded as the potential natural and safe antimicrobial alternatives for food preservation and improvement. The extracts from many plants, which are commonly used as spices and flavoring agents, were evaluated as antibacterial agents against serious foodborne pathogens, for example Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus, and Escherichia coli O157:H7, using qualitative and quantitative assaying methods. Dairy-based media were also used for evaluating the practical application of plant extracts as antimicrobial agents. Most of the examined plant extracts exhibited remarkable antibacterial activity; the extracts of cinnamon, cloves, garden cress, and lemon grass were the most powerful, either in synthetic or in dairy-based media. Flavoring processed cheese with plant extracts resulted in the enhancement of cheese sensory attributes, for example odor, taste, color, and overall quality, especially in flavored samples with cinnamon, lemon grass, and oregano. It can be concluded that plant extracts are strongly recommended, as powerful and safe antibacterial and flavoring agents, for the preservation and sensory enhancement of processed cheese. © 2015 Institute of Food Technologists®

Chiral lactic hydrazone derivatives as potential bioactive antibacterial agents: Synthesis, spectroscopic, structural and molecular docking studies

NASA Astrophysics Data System (ADS)

Noshiranzadeh, Nader; Heidari, Azam; Haghi, Fakhri; Bikas, Rahman; Lis, Tadeusz

2017-01-01

A series of novel chiral lactic-hydrazone derivatives were synthesized by condensation of (S)-lactic acid hydrazide with salicylaldehyde derivatives and characterized by elemental analysis and spectroscopic studies (FT-IR, 1H NMR and 13C NMR spectroscopy). The structure of one compound was determined by single crystal X-ray analysis. Antibacterial activity of the synthesized compounds was studied against Staphylococcus aureus, Streptococcus pneumonia, Escherichia coli and Pseudomonas aeruginosa as bacterial cultures by broth microdilution method. All of the synthesized compounds showed good antibacterial activity with MIC range of 64-512 μg/mL. Compounds (S,E)-2-hydroxy-N-(2-hydroxy-5-nitrobenzylidene)propanehydrazide (5) and (S,E)-2-hydroxy-N-((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)propanehydrazide (7) were the most effective antibacterial derivatives against S. aureus and E. coli respectively with a MIC value of 64 μg/mL. Bacterial biofilm formation assay showed that these compounds significantly inhibited biofilm formation of P. aeruginosa. Also, in silico molecular docking studies were performed to show lipoteichoic acid synthase (LtaS) inhibitory effect of lactic hydrazone derivatives. The association between electronic and structural effects of some substituents on the benzylidene moiety and the biological activity of these chiral compounds were studied. Structural studies show that compound with higher hydrogen bonding interactions show higher antibacterial activity. The results show chiral hydrazone derivatives based on lactic acid hydrazide could be used as potential lead compounds for developing novel antibacterial agents.

Does implant coating with antibacterial-loaded hydrogel reduce bacterial colonization and biofilm formation in vitro?

PubMed

Drago, Lorenzo; Boot, Willemijn; Dimas, Kostantinos; Malizos, Kostantinos; Hänsch, Gertrud M; Stuyck, Jos; Gawlitta, Debby; Romanò, Carlo L

2014-11-01

Implant-related infections represent one of the most severe complications in orthopaedics. A fast-resorbable, antibacterial-loaded hydrogel may reduce or prevent bacterial colonization and biofilm formation of implanted biomaterials. We asked: (1) Is a fast-resorbable hydrogel able to deliver antibacterial compounds in vitro? (2) Can a hydrogel (alone or antibacterial-loaded) coating on implants reduce bacterial colonization? And (3) is intraoperative coating feasible and resistant to press-fit implant insertion? We tested the ability of Disposable Antibacterial Coating (DAC) hydrogel (Novagenit Srl, Mezzolombardo, Italy) to deliver antibacterial agents using spectrophotometry and a microbiologic assay. Antibacterial and antibiofilm activity were determined by broth microdilution and a crystal violet assay, respectively. Coating resistance to press-fit insertion was tested in rabbit tibias and human femurs. Complete release of all tested antibacterial compounds was observed in less than 96 hours. Bactericidal and antibiofilm effect of DAC hydrogel in combination with various antibacterials was shown in vitro. Approximately 80% of the hydrogel coating was retrieved on the implant after press-fit insertion. Implant coating with an antibacterial-loaded hydrogel reduces bacterial colonization and biofilm formation in vitro. A fast-resorbable, antibacterial-loaded hydrogel coating may help prevent implant-related infections in orthopaedics. However, further validation in animal models and properly controlled human studies is required.

Quick identification of kuraridin, a noncytotoxic anti-MRSA (methicillin-resistant Staphylococcus aureus) agent from Sophora flavescens using high-speed counter-current chromatography.

PubMed

Chan, Ben Chung-Lap; Yu, Hua; Wong, Chun-Wai; Lui, Sau-Lai; Jolivalt, Claude; Ganem-Elbaz, Carine; Paris, Jean-Marc; Morleo, Barbara; Litaudon, Marc; Lau, Clara Bik-San; Ip, Margaret; Fung, Kwok-Pui; Leung, Ping-Chung; Han, Quan-Bin

2012-01-01

Bacterial resistance to antibiotics has become a serious problem of public health that concerns almost all currently used antibacterial agents and that manifests in all fields of their application. To find more antibacterial agents from natural resources is all the time considered as an important strategy. Sophora flavescens is a popularly used antibacterial herb in Chinese Medicine, from which prenylated flavones were reported as the antibacterial ingredients but with a major concern of toxicity. In our screening on the antibacterial activities of various chemicals of this herb, 18 fractions were obtained from 8 g of 50% ethanol extract on a preparative high-speed counter-current chromatography (HSCCC, 1000 ml). The system of n-hexane/ethyl acetate/methanol/water (1:1:1:1) was used as the two-phase separation solvent. A chalcone named kuraridin was isolated from the best anti-MRSA fraction, together with sophoraflavanone G, a known active ingredient of S. flavescens. Their structures were elucidated by analysis of the NMR spectra. Both compounds exhibited significant anti-MRSA effects, compared to baicalein that is a well known anti-MRSA natural product. More important, kuraridin showed no toxicity on human peripheral blood mononuclear cells (PBMC) at the concentration up to 64 μg/ml while sophoraflavanone G inhibited over 50% of cellular activity at 4 μg/ml or higher concentration. These data suggested that opening of ring A of the prenylated flavones might decrease the toxicity and remain the anti-MRSA effect, from a viewpoint of structure-activity relationship. Copyright © 2011 Elsevier B.V. All rights reserved.

Disinfection of Water with Quaternary Ammonium Salts Insolubilized on a Porous Glass Surface

PubMed Central

Nakagawa, Yoshihiro; Hayashi, Hiroyuki; Tawaratani, Takahiko; Kourai, Hiroki; Horie, Tokunaru; Shibasaki, Isao

1984-01-01

Insoluble quaternary ammonium salts bound to porous glass showed antibacterial activity. An agent designated as G12, which had a dodecyl alkyl chain, was selected for some antibacterial tests on comparison of it with the agent reported previously. The antibacterial activity of G12 toward Escherichia coli was mainly due to the adsorption of cells and therefore gradually decreased during continuous treatment of a cell suspension. The lost G12 activity was completely recovered by washing with ethanol, and the activity of refreshed G12 decreased in the same manner as that of fresh G12. The lost activity was, however, always recovered only by ethanol treatment. This indicated that G12 might interact with cells more strongly by means of a hydrophobic force than an electrostatic one. The antimicrobial spectrum showed that G12 was effective against not only bacteria but also yeasts. PMID:16346491

Phytochemical analysis of Andrographis paniculata and Orthosiphon stamineus leaf extracts for their antibacterial and antioxidant potential.

PubMed

Malahubban, M; Alimon, A R; Sazili, A Q; Fakurazi, S; Zakry, F A

2013-09-01

Leaves of Andrographis paniculata and Orthosiphon stamineus were extracted with water, ethanol, methanol and chloroform to assess their potential as antibacterial and antioxidant agents. High performance liquid chromatography analysis showed that the methanolic extracts of A. paniculata and O. stamineus leaves gave the highest amounts of andrographolide and rosmarinic acid, respectively. These leaf extracts exhibited antimicrobial and antioxidant activities and, at the highest concentration tested (200 mg/mL), showed greater inhibitory effects against the Gram positive bacteria Bacillus cereus and Staphylococcus aureus than 10% acetic acid. Andrographis paniculata and O. stamineus methanolic and ethanolic leaf extracts also showed the strongest antioxidant activity as compared with the other extracts tested. The bioactive compounds present in these leaf extracts have the potential to be developed into natural antibacterial and antioxidant agents that may have applications in animal and human health.

ESKAPEing the labyrinth of antibacterial discovery.

PubMed

Tommasi, Ruben; Brown, Dean G; Walkup, Grant K; Manchester, John I; Miller, Alita A

2015-08-01

Antimicrobial drug resistance is a growing threat to global public health. Multidrug resistance among the 'ESKAPE' organisms - encompassing Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. - is of particular concern because they are responsible for many serious infections in hospitals. Although some promising agents are in the pipeline, there is an urgent need for new antibiotic scaffolds. However, antibacterial researchers have struggled to identify new small molecules with meaningful cellular activity, especially those effective against multidrug-resistant Gram-negative pathogens. This difficulty ultimately stems from an incomplete understanding of efflux systems and compound permeation through bacterial membranes. This Opinion article describes findings from target-based and phenotypic screening efforts carried out at AstraZeneca over the past decade, discusses some of the subsequent chemistry challenges and concludes with a description of new approaches comprising a combination of computational modelling and advanced biological tools which may pave the way towards the discovery of new antibacterial agents.

Laboratory Evaluation of 3-(5-Tetrazolyl)Penam, a New Semisynthetic Beta-Lactam Antibacterial Agent with Extended Broad-Spectrum Activity

PubMed Central

English, Arthur R.; Retsema, James A.; Lynch, John E.

1976-01-01

In the new agent 3-(5-tetrazolyl)penam, hereafter referred to as CP-35,587, the carboxyl function at C3 in the penicillin nucleus has been replaced with the 5-tetrazolyl moiety. Marked changes in spectrum and resistance to gram-negative β-lactamases, particularly with regard to Klebsiella pneumoniae isolates, were conferred by this modification. The anti-Klebsiella activity clearly distinguishes the antibacterial spectrum of CP-35,587 from any known broad-spectrum penicillin. Compared to orally active cephalosporins, the spectrum advantage of CP-35,587 encompasses Enterobacter, Serratia marcescens, Citrobacter, Providencia, Haemophilus influenzae, and Streptococcus faecalis, both in vitro and in murine infections produced by many of the above-named microorganisms. Thus, CP-35,587 combines and extends the antibacterial activity of broad-spectrum penicillins and orally active cephalosporins. PMID:984745

Antibacterial activity of nitric oxide releasing silver nanoparticles

NASA Astrophysics Data System (ADS)

Seabra, Amedea B.; Manosalva, Nixson; de Araujo Lima, Bruna; Pelegrino, Milena T.; Brocchi, Marcelo; Rubilar, Olga; Duran, Nelson

2017-06-01

Silver nanoparticles (AgNPs) are well known potent antimicrobial agents. Similarly, the free radical nitric oxide (NO) has important antibacterial activity, and due to its instability, the combination of NO and nanomaterials has been applied in several biomedical applications. The aim of this work was to synthesize, characterize and evaluate the antibacterial activity of a new NO-releasing AgNPs. Herein, AgNPs were synthesized by the reduction of silver ions (Ag+) by catechin, a natural polyphenol and potent antioxidant agent, derived from green tea extract. Catechin acts as a reducing agent and as a capping molecule on the surface of AgNPs, minimizing particle agglomeration. The as-synthesized nanoparticles were characterized by different techniques. The results showed the formation of AgNPs with average hydrodynamic size of 44 nm, polydispersity index of 0.21, and zeta potential of -35.9 mV. X-ray diffraction and Fourier transform infrared spectroscopy revealed the presence of the AgNP core and cathecin as capping agent. The low molecular weight mercaptosuccinic acid (MSA), which contain free thiol group, was added on the surface of catechin-AgNPs, leading to the formation of MSA-catechin-AgNPs (the NO precursor nanoparticle). Free thiol groups of MSA-catechin-AgNPs were nitrosated leading to the formation of S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), the NO donor. The amount of 342 ± 16 µmol of NO was released per gram of S-nitroso-MSA-catechin-AgNPs. The antibacterial activities of catechin-AgNPs, MSA-catechin-AgNPs, and S-nitroso-MSA-catechin-AgNPs were evaluated towards different resistant bacterial strains. The results demonstrated an enhanced antibacterial activity of the NO-releasing AgNP. For instance, the minimal inhibitory concentration values for Pseudomonas aeruginosa (ATCC 27853) incubated with AgNPs-catechin, AgNPs-catechin-MSA, and AgNPs-catechin-S-nitroso-MSA were found to be 62, 125 and 3 µg/mL, respectively. While in the case of Klebsiella pneumoniae (ATCC 700603) the minimum bactericidal concentration values for treatments with AgNPs-catechin, AgNPs-catechin-MSA, and AgNPs-catechin-S-nitroso-MSA were found to be 1000, 500, and 125 µg/mL, respectively. The antibacterial actions of the NO-releasing nanoparticle were superior in comparison with the antibacterial effects of AgNPs, in most of the tested antibiotic resistant bacteria strains. These results highlight the promising uses of NO-releasing AgNPs against resistant bacteria in several biomedical applications.

Antibacterial and cytotoxic activities of the sesquiterpene lactones cnicin and onopordopicrin.

PubMed

Bach, Sandra M; Fortuna, Mario A; Attarian, Rodgoun; de Trimarco, Juliana T; Catalán, César A N; Av-Gay, Yossef; Bach, Horacio

2011-02-01

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens.

Comparison of the antibacterial activity of chelating agents using the agar diffusion method

USDA-ARS?s Scientific Manuscript database

The agar diffusion assay was used to examine antibacterial activity of 2 metal chelators. Concentrations of 0 to 40 mM of ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N,N’-disuccinic acid (EDDS) were prepared in 1.0 M potassium hydroxide (KOH). The pH of the solutions was adjusted to 1...

Antibacterial activity of antipsychotic agents, their association with lipid nanocapsules and its impact on the properties of the nanocarriers and on antibacterial activity.

PubMed

Nehme, Hassan; Saulnier, Patrick; Ramadan, Alyaa A; Cassisa, Viviane; Guillet, Catherine; Eveillard, Matthieu; Umerska, Anita

2018-01-01

Bacterial antibiotic resistance is an emerging public health problem worldwide; therefore, new therapeutic strategies are needed. Many studies have described antipsychotic compounds that present antibacterial activity. Hence, the aims of this study were to evaluate the in vitro antibacterial activity of antipsychotics belonging to different chemical families, to assess the influence of their association with lipid nanocapsules (LNCs) on their antimicrobial activity as well as drug release and to study the uptake of LNCs by bacterial cells. Antibacterial activity was evaluated against Gram-positive Staphylococcus aureus and Gram negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii by minimum inhibitory concentration (MIC) assay, and the capability of killing tested microorganisms was evaluated by time kill assay. LNCs were prepared by phase inversion method, and the antipsychotic agents were incorporated using pre-loading and post-loading strategies. Only phenothiazines and thioxanthenes showed antibacterial activity, which was independent of antibiotic-resistance patterns. Loading the nanocarriers with the drugs affected the properties of the former, particularly their zeta potential. The release rate depended on the drug and its concentration-a maximum of released drug of less than 40% over 24 hours was observed for promazine. The influence of the drug associations on the antibacterial properties was concentration-dependent since, at low concentrations (high nanocarrier/drug ratio), the activity was lost, probably due to the high affinity of the drug to nanocarriers and slow release rate, whereas at higher concentrations, the activity was well maintained for the majority of the drugs. Chlorpromazine and thioridazine increased the uptake of the LNCs by bacteria compared with blank LNCs, even below the minimum inhibitory concentration.

Benzaldehyde Schiff bases regulation to the metabolism, hemolysis, and virulence genes expression in vitro and their structure-microbicidal activity relationship.

PubMed

Xia, Lei; Xia, Yu-Fen; Huang, Li-Rong; Xiao, Xiao; Lou, Hua-Yong; Liu, Tang-Jingjun; Pan, Wei-Dong; Luo, Heng

2015-06-05

There is an urgent need to develop new antibacterial agents because of multidrug resistance by bacteria and fungi. Schiff bases (aldehyde or ketone-like compounds) exhibit intense antibacterial characteristics, and are therefore, promising candidates as antibacterial agents. To investigate the mechanism of action of newly designed benzaldehyde Schiff bases, a series of high-yielding benzaldehyde Schiff bases were synthesized, and their structures were determined by NMR and MS spectra data. The structure-microbicidal activity relationship of derivatives was investigated, and the antibacterial mechanisms were investigated by gene assays for the expression of functional genes in vitro using Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The active compounds were selective for certain active groups. The polar substitution of the R2 group of the amino acids in the Schiff bases, affected the antibacterial activity against E. coli and S. aureus; specific active group at the R3 or R4 groups of the acylhydrazone Schiff bases could improve their inhibitory activity against these three tested organisms. The antibacterial mechanism of the active benzaldehyde Schiff bases appeared to regulate the expression of metabolism-associated genes in E. coli, hemolysis-associated genes in B. subtilis, and key virulence genes in S. aureus. Some benzaldehyde Schiff bases were bactericidal to all the three strains and appeared to regulate gene expression associated with metabolism, hemolysis, and virulence, in vitro. The newly designed benzaldehyde Schiff bases possessed unique antibacterial activity and might be potentially useful for prophylactic or therapeutic intervention of bacterial infections. Copyright © 2015. Published by Elsevier Masson SAS.

Sebaceous adenitis and mural folliculitis in a cat responsive to topical fatty acid supplementation.

PubMed

Glos, Katharina; von Bomhard, Wolf; Bettenay, Sonya; Mueller, Ralf S

2016-02-01

To describe a case of feline sebaceous adenitis and mural folliculitis, and its successful treatment with topical fatty acids. A 5-year-old, male castrated Norwegian Forest cat was presented with a progressive seborrhoeic dermatitis. Clinical examination and histopathological examination of skin biopsies. There was severe, multifocal, lymphocytic mural folliculitis and perifollicular dermatitis, moderate hyperkeratosis and sebaceous adenitis on histopathology. Sebaceous glands were either absent or almost completely effaced by a dense lymphocytic infiltrate. Clinical signs began in spring on the face and neck and progressed over an 18 month period to involve the legs. Initially, topical and systemic antibacterial therapy for a mild bacterial overgrowth resulted in partial clinical response. There was no improvement with oral omega 6 fatty acids and surface cleaning. Treatment with a spot-on product containing essential oils, smoothing agents and vitamin E as the sole therapy was associated with a good--but incomplete--clinical response over a 6 month period, with hair regrowth and a marked decrease in seborrhoeic dermatitis. This improvement was sustained until 12 months later when a severe deep pyoderma with associated anorexia and depression occurred. This was symptomatically treated and the cat remained clinically stable for a further 18 months. Periocular and perinasal seborrhoea was a persistent feature. Topical essential fatty acid therapy may offer a viable alternative to ciclosporin, which has been reported for the successful treatment of this rare disease in cats. © 2015 ESVD and ACVD.

Antiprotozoal, antimycobacterial, and anti-inflammatory evaluation of Cnidoscolus chayamansa (Mc Vaugh) extract and the isolated compounds.

PubMed

Pérez-González, Mariana Z; Gutiérrez-Rebolledo, Gabriel A; Yépez-Mulia, Lilián; Rojas-Tomé, Irma S; Luna-Herrera, Julieta; Jiménez-Arellanes, María A

2017-05-01

Cnidoscolus chayamansa is a medicinal and edible plant known as Chaya, is commonly used as an anti-inflammatory, antiprotozoal, antibacterial agent and as a remedy for respiratory illness, gastrointestinal disorders, and vaginal infections related with the inflammation process. In this paper, we describe the plant's phytochemical analysis and biological activities (antimycobacterial, antibacterial, antiprotozoal, and anti-inflammatory properties) of the CHCl 3 :MeOH (1:1) leaves extract and isolated compounds, as well as the acute and sub-acute toxic effects. Chemical identification of isolated compounds was performed by 1 H- and 13 C NMR spectra data. In vitro antibacterial and antimycobacterial activities were determined by disc diffusion and MABA assays, respectively; antiprotozoal test by means of the sub-culture test. Topical and systemic anti-inflammatory effects were tested by TPA and carrageenan assay on BALB/c mice. Moretenol, moretenyl acetate, kaempferol-3,7-dimethyl ether, and 5-hydroxy-7-3',4'-trimethoxyflavanone were the main compounds isolated. The CHCl 3 :MeOH extract showed antiprotozoal (IC 50 ≤65.29μg/mL), antimycobacterial (MIC≤50μg/mL), and anti-inflammatory activities (ED 50 =1.66mg/ear and 467.73mg/kg), but was inactive against the bacterial strains tested. The LD 50 for extract was >2g/kg. In the sub-acute toxicity test, the extract was administered at 1g/kg for 28days and did not cause lethality or any alteration in hematological and biochemical parameters; in addition, liver, kidney, and spleen histological analysis exhibited no structural changes. Moretenol and moretenyl acetate showed MIC=25μg/mL against Mycobacterium tuberculosis H37Rv and against four monoresistant strains of M. tuberculosis H37Rv. Both compounds exhibited moderate activity against Entamoeba histolytica and Giardia lamblia (IC 50 ≤71.70μg/mL). Kaempferol-3,7-dimethyl ether and 5-hydroxy-7-3',4'-trimethoxy-flavanone were more active than the extract against E. histolytica and G. lamblia, showing IC 50 ≤27.43μg/mL. As topical anti-inflammatory agents, moretenol and kaempferol-3,7-dimethyl ether were the most active compounds inhibiting the edema in 30.52 and 26.67%, respectively. Moretenol and moretenyl acetate showed significant antimycobacterial and antiprotozoal activities; in addition, important antiprotozoal effect was detected with kaempferol-3,7-dimethyl ether and 5-hydroxy-7-3',4'-trimethoxyflavanone. The extract and the terpenoids possess good anti-inflammatory activity. The extract did not produce lethality or adverse effects in acute and sub-acute tests. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Expansion of Antibacterial Spectrum of Muraymycins toward Pseudomonas aeruginosa.

PubMed

Takeoka, Yusuke; Tanino, Tetsuya; Sekiguchi, Mitsuaki; Yonezawa, Shuji; Sakagami, Masahiro; Takahashi, Fumiyo; Togame, Hiroko; Tanaka, Yoshikazu; Takemoto, Hiroshi; Ichikawa, Satoshi; Matsuda, Akira

2014-05-08

It is urgent to develop novel anti-Pseudomonas agents that should also be active against multidrug resistant P. aeruginosa. Expanding the antibacterial spectrum of muraymycins toward P. aeruginosa was investigated by the systematic structure-activity relationship study. It was revealed that two functional groups, a lipophilic side chain and a guanidino group, at the accessory moiety of muraymycins were important for the anti-Pseudomonas activity, and analogue 29 exhibited antibacterial activity against a range of P. aeruginosa strains with the minimum inhibitory concentration values of 4-8 μg/mL.

Expansion of Antibacterial Spectrum of Muraymycins toward Pseudomonas aeruginosa

PubMed Central

2014-01-01

It is urgent to develop novel anti-Pseudomonas agents that should also be active against multidrug resistant P. aeruginosa. Expanding the antibacterial spectrum of muraymycins toward P. aeruginosa was investigated by the systematic structure–activity relationship study. It was revealed that two functional groups, a lipophilic side chain and a guanidino group, at the accessory moiety of muraymycins were important for the anti-Pseudomonas activity, and analogue 29 exhibited antibacterial activity against a range of P. aeruginosa strains with the minimum inhibitory concentration values of 4–8 μg/mL. PMID:24900879

Synthesis and biological evaluation of novel 5-aryl-4-(5-nitrofuran-2-yl)-pyrimidines as potential anti-bacterial agents.

PubMed

Verbitskiy, Egor V; Baskakova, Svetlana A; Gerasimova, Natal'ya A; Evstigneeva, Natal'ya P; Zil'berberg, Natal'ya V; Kungurov, Nikolay V; Kravchenko, Marionella A; Skornyakov, Sergey N; Pervova, Marina G; Rusinov, Gennady L; Chupakhin, Oleg N; Charushin, Valery N

2017-07-01

A facile two-step synthetic approach to fluorinated and non-fluorinated 5-aryl-4-(5-nitrofuran-2-yl)-pyrimidines from readily available 5-bromo-4-(furan-2-yl)pyrimidine has been developed. All synthesized compounds were screened in vitro for their antibacterial activities against twelve various bacterial strains. It is demonstrated that some of these compounds exhibited significant antibacterial activities against strains Neisseria gonorrhoeae and Staphylococcus aureus, comparable and even higher with that commercial drug Spectinomycin. Copyright © 2017 Elsevier Ltd. All rights reserved.

Report: Studies on antibacterial activity of some traditional medicinal plants used in folk medicine.

PubMed

Israr, Fozia; Hassan, Fouzia; Naqvi, Baqir Shyum; Azhar, Iqbal; Jabeen, Sabahat; Hasan, S M Farid

2012-07-01

Ethanolic extracts of eight medicinal plants commonly used in folk medicine were tested for their antibacterial activity against four Gram positive strains (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and, Streptococcus pneumoniae) and six Gram negative strains (Escherichia coli, Proteus vulgaris, Proteus mirabilis. Salmonella typhi para A, Salmonella typhi para B and Shigella dysenteriae) that were obtained from different pathological laboratories located in Karachi, Pakistan. Disc diffusion method was used to analyze antibacterial activity. Out of eight, five medicinal plants showed antibacterial activity against two or more than two microbial species. The most effective antimicrobial plant found to be Punica granatum followed by Curcuma zedoaria Rosc, Grewia asiatica L and Carissa carandas L, Curcuma caesia Roxb respectively. From these results, it is evident that medicinal plants could be used as a potential source of new antibacterial agents.

Antibiotic-loaded, silver core-embedded mesoporous silica nanovehicles as a synergistic antibacterial agent for the treatment of drug-resistant infections.

PubMed

Wang, Yao; Ding, Xiali; Chen, Yuan; Guo, Mingquan; Zhang, Yan; Guo, Xiaokui; Gu, Hongchen

2016-09-01

Drug-resistant bacterial infections have become one of the most serious risks in public health as they make the conventional antibiotics less efficient. There is an urgent need for developing new generations of antibacterial agents in this field. In this work, a nanoplatform of LEVO-loaded and silver core-embedded mesoporous silica nanovehicles (Ag@MSNs@LEVO) is demonstrated as a synergistic antibacterial agent for the treatment of drug-resistant infections both in vitro and in vivo. The combination of the inner Ag core and the loaded antibiotic drug in mesopores endows the single-particle nanoplatform with a synergistic effect on killing the drug-resistant bacteria. The nanoplatform of Ag@MSNs@LEVO exhibits superior antibacterial activity to LEVO-loaded MSNs (MSNs@LEVO) and silver core-embedded MSNs (Ag@MSNs) in vitro. In the in vivo acute peritonitis model, the infected drug-resistant Escherichia coli GN102 in peritoneal cavity of the mice is reduced by nearly three orders of magnitude and the aberrant pathological feature of spleen and peritoneum disappears after treatment with Ag@MSNs@LEVO. Importantly, this nanopaltform renders no obvious toxic side effect to the mice during the tested time. There is no doubt that this study strongly indicates a promising potential of Ag@MSNs@LEVO as a synergistic and safety therapy tool for the clinical drug-resistant infections. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical and mineralogical characteristics of French green clays used for healing

USGS Publications Warehouse

Williams, Lynda B.; Haydel, Shelley E.; Giese, Rossman F.; Eberl, Dennis D.

2008-01-01

The worldwide emergence of infectious diseases, together with the increasing incidence of antibiotic-resistant bacteria, elevate the need to properly detect, prevent, and effectively treat these infections. The overuse and misuse of common antibiotics in recent decades stimulates the need to identify new inhibitory agents. Therefore, natural products like clays, that display antibacterial properties, are of particular interest.The absorptive properties of clay minerals are well documented for healing skin and gastrointestinal ailments. However, the antibacterial properties of clays have received less scientific attention. French green clays have recently been shown to heal Buruli ulcer, a necrotic or ‘flesh-eating’ infection caused by Mycobacterium ulcerans. Assessing the antibacterial properties of these clays could provide an inexpensive treatment for Buruli ulcer and other skin infections.Antimicrobial testing of the two clays on a broad-spectrum of bacterial pathogens showed that one clay promotes bacterial growth (possibly provoking a response from the natural immune system), while another kills bacteria or significantly inhibits bacterial growth. This paper compares the mineralogy and chemical composition of the two French green clays used in the treatment of Buruli ulcer.Mineralogically, the two clays are dominated by 1Md illite and Fe-smectite. Comparing the chemistry of the clay minerals and exchangeable ions, we conclude that the chemistry of the clay, and the surface properties that affect pH and oxidation state, control the chemistry of the water used to moisten the clay poultices and contribute the critical antibacterial agent(s) that ultimately debilitate the bacteria.

ent-Copalic acid antibacterial and anti-biofilm properties against Actinomyces naeslundii and Peptostreptococcus anaerobius.

PubMed

Souza, Maria Gorete Mendes de; Leandro, Luís Fernando; Moraes, Thaís da Silva; Abrão, Fariza; Veneziani, Rodrigo Cassio Sola; Ambrosio, Sergio Ricardo; Martins, Carlos Henrique Gomes

2018-05-28

Diterpenes are an important class of plant metabolites that can be used in the search for new antibacterial agents. ent-Copalic acid (CA), the major diterpene in Copaifera species exudates, displays several pharmacological properties. This study evaluates the CA antibacterial potential against the anaerobic bacteria Peptostreptococcus anaerobius and Actinomyces naeslundii. Antimicrobial assays included time-kill and biofilm inhibition and eradication assays. Time-kill assays conducted for CA concentrations between 6.25 and 12.5 μg/mL evidenced bactericidal activity within 72 h. CA combined with chlorhexidine dihydrochloride (CHD) exhibited bactericidal action against P. anaerobius within 6 h of incubation. As for A. naeslundii, the same combination reduced the number of microorganisms by over 3 log10 at 24 h and exerted a bactericidal effect at 48 h of incubation. CA at 500 and 2000 μg/mL inhibited P. anaerobius and A. naeslundii biofilm formation by at least 50%, respectively. CA at 62.5 and 1.000 μg/mL eradicated 99.9% of pre-formed P. anaerobius and A. naeslundii biofilms, respectively. These results indicated that CA presents in vitro antibacterial activity and is a potential biofilm inhibitory agent. This diterpene may play an important role in the search for novel sources of agents that can act against anaerobic bacteria. Copyright © 2018 Elsevier Ltd. All rights reserved.

Chitosan-solid lipid nanoparticles as carriers for topical delivery of tretinoin.

PubMed

Ridolfi, Daniela M; Marcato, Priscyla D; Justo, Giselle Z; Cordi, Lívia; Machado, Daisy; Durán, Nelson

2012-05-01

Tretinoin (TRE) or all-trans retinoic acid is employed in the topical treatment of various skin diseases including acne and psoriasis. However, its use is strongly limited by side effects and high chemical instability. TRE encapsulation in nanostructured systems reduces these problems. Chitosan is a biopolymer that exhibits a number of interesting properties such as bioadhesion and antibacterial activity. The aim of this work was to prepare and characterize solid lipid nanoparticles (SLN) containing TRE, with and without addition of chitosan, to assess their in vitro cytotoxicity in keratinocytes and to evaluate their antibacterial activity against bacteria related to acne. SLN without (SLN-TRE) and with (SLN-chitosan-TRE) chitosan were prepared by hot high pressure homogenization. The hydrodynamic mean diameter and zeta potential were 162.7±1.4 nm and -31.9±2.0 mV for SLN-TRE, and 284.8±15.0 nm and 55.9±3.1 mV for SLN-chitosan-TRE. The SLN-chitosan-TRE exhibited high encapsulation efficiency, high physical stability in the tested period (one year), were not cytotoxic to keratinocytes and showed high antibacterial activity against P. acnes and S. aureus. Therefore chitosan-SLN can be good candidates to encapsulate TRE and to increase its therapeutic efficacy in the topical treatment of acne. Copyright © 2011 Elsevier B.V. All rights reserved.

Discovery of 2-aminothiazolyl berberine derivatives as effectively antibacterial agents toward clinically drug-resistant Gram-negative Acinetobacter baumanii.

PubMed

Gao, Wei-Wei; Gopala, Lavanya; Bheemanaboina, Rammohan R Yadav; Zhang, Guo-Biao; Li, Shuo; Zhou, Cheng-He

2018-02-25

Aminothiazolyl berberine derivatives as potentially antimicrobial agents were designed and synthesized in an effort to overcome drug resistance. The antimicrobial assay revealed that some target compounds exhibited significantly inhibitory efficiencies toward bacteria and fungi including drug-resistant pathogens, and the aminothiazole and Schiff base moieties were helpful structural fragments for aqueous solubility and antibacterial activity. Especially, aminothiazolyl 9-hexyl berberine 9c and 2,4-dichlorobenzyl derivative 18a exhibited good activities (MIC = 2 nmol/mL) against clinically drug-resistant Gram-negative Acinetobacter baumanii with low cytotoxicity to hepatocyte LO2 cells, rapidly bactericidal effects and quite slow development of bacterial resistance toward A. baumanii. Molecular modeling indicated that compounds 9c and 18a could bind with GLY-102, ARG-136 and/or ALA-100 residues of DNA gyrase through hydrogen bonds. It was found that compounds 9c and 18a were able to disturb the drug-resistant A. baumanii membrane effectively, and molecule 9c could not only intercalate but also cleave bacterial DNA isolated from resistant A. baumanii, which might be the preliminary antibacterial action mechanism of inhibiting the growth of A. baumanii strain. In particular, the combination use of compound 9c with norfloxacin could enhance the antibacterial activity, broaden antibacterial spectrum and overcome the drug resistance. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Intensity and duration of in-vitro antibacterial activity of different adhesives used in orthodontics.

PubMed

Passariello, Claudio; Sannino, Gianpaolo; Petti, Stefano; Gigola, Pierangelo

2014-04-01

This work investigated the antibacterial activity of 14 bonding agents to predict their ability to inhibit white-spot development during orthodontic treatment. Standardized, sterilized disks of each material were continuously rinsed (for up to 180 d) in a flow of sterile saline. At predetermined time points, the residual ability of each material to inhibit bacterial growth (determined by measuring the size of inhibition halos around disks placed onto appropriate culture media seeded with Streptococcus gordonii DSM6777, Streptococcus sanguinis DSM20567, Streptococcus mutans DSM20523, or Lactobacillus acidophilus DSM20079) and biofilm formation (determined by measuring the numbers of bacteria adherent to disks following incubation in appropriate broths) was tested in triplicate and compared with the baseline activities of freshly prepared materials. Overall antibacterial and anti-biofilm activities, adjusted for exposure time and strain of bacteria, were assessed. The decrease of antibacterial activity was faster (30-60 d) and complete for fluoride-enriched materials, but slower (90 d) and partial for antimicrobial-containing materials (benzalkonium chloride, zinc oxide, chlorexidine, or MDPB). Materials enriched with benzalkonium chloride, chlorexidine, or MDPB showed the highest antibacterial activities. Anti-biofilm assays yielded similar results. These data could be helpful for clinicians in the choice of the best performing bonding agent also in light of duration of the clinical application. © 2014 Eur J Oral Sci.

Hidradenitis Suppurativa

MedlinePlus

... the area with anti-bacterial soap. Non-steroidal anti-inflammatory drugs (NSAIDs) can help reduce swelling and relieve pain. More severe cases may require antibiotics. These can be topical (applied to your skin) ...

Should antibacterials be deregulated?

PubMed

Rovira, J; Figueras, M; Segú, J L

1998-05-01

Deregulation of antibacterials is a recurrent topic in the debate on pharmaceutical policy. This article focuses on one aspect of pharmaceutical regulation, namely the requirement of a medical prescription for purchasing antibacterials. However, a strategy of deregulation should not only concern the switch from prescription-only status to nonprescription status for a given drug, but should consider some complementary measures to minimise potentially harmful effects on health and costs. Risk-benefit and economic evaluations, which are possible approaches to assess the convenience of antibacterial deregulation, force the empirical evidence, the assumptions, as well as the value judgements on which the options are evaluated, to be made explicit. We outline the basic traits of an economic-evaluation approach to assess the issues related to the public interest and the feasibility of a deregulation policy. However, the answer cannot be a generic one, but should address the question for each particular country, and for each antibacterial and indication. Given the limitations of existing evidence on that issue, a tentative research agenda is also proposed.

Nanotechnology: A Valuable Strategy to Improve Bacteriocin Formulations

PubMed Central

Fahim, Hazem A.; Khairalla, Ahmed S.; El-Gendy, Ahmed O.

2016-01-01

Bacteriocins are proteinaceous antibacterial compounds, produced by diverse bacteria, which have been successfully used as: (i) food biopreservative; (ii) anti-biofilm agents; and (iii) additives or alternatives to the currently existing antibiotics, to minimize the risk of emergence of resistant strains. However, there are several limitations that challenge the use of bacteriocins as biopreservatives/antibacterial agents. One of the most promising avenues to overcome these limitations is the use of nanoformulations. This review highlights the practical difficulties with using bacteriocins to control pathogenic microorganisms, and provides an overview on the role of nanotechnology in improving the antimicrobial activity and the physicochemical properties of these peptides. PMID:27695440

Recent advances in medicinal chemistry of sulfonamides. Rational design as anti-tumoral, anti-bacterial and anti-inflammatory agents.

PubMed

Shah, Syed Shoaib Ahmad; Rivera, Gildardo; Ashfaq, Muhammad

2013-01-01

Now-a-days, cancer is becoming one of the major problems of public health in the world. Pharmacology treatment is a way to increase quality and long life. Predominantly, in last decade sulfonamide derivatives have been described as potential carbonic anhydrase inhibitors. In the present work, we describe recent advances during the last decade in medicinal chemistry of sulfonamides derivatives with some examples of rational design as anti-tumoral, antibacterial and anti-inflammatory agents. We show strategy design, structure-activity relationship, biological activity and advances of new sulfonamide compounds that have more health significance than some clinically used sulfonamides.

In Situ Synthesis of Silver Nanoparticles in a Hydrogel of Carboxymethyl Cellulose with Phthalated-Cashew Gum as a Promising Antibacterial and Healing Agent.

PubMed

Lustosa, Ana Karina Marques Fortes; de Jesus Oliveira, Antônia Carla; Quelemes, Patrick Veras; Plácido, Alexandra; da Silva, Francilene Vieira; Oliveira, Irisdalva Sousa; de Almeida, Miguel Peixoto; Amorim, Adriany das Graças Nascimento; Delerue-Matos, Cristina; de Oliveira, Rita de Cássia Meneses; da Silva, Durcilene Alves; Eaton, Peter; de Almeida Leite, José Roberto de Souza

2017-11-12

Silver nanoparticles have been shown to possess considerable antibacterial activity, but in vivo applications have been limited due to the inherent, but low, toxicity of silver. On the other hand, silver nanoparticles could provide cutaneous protection against infection, due to their ability to liberate silver ions via a slow release mechanism, and their broad-spectrum antimicrobial action. Thus, in this work, we describe the development of a carboxymethyl cellulose-based hydrogel containing silver nanoparticles. The nanoparticles were prepared in the hydrogel in situ, utilizing two variants of cashew gum as a capping agent, and sodium borohydride as the reducing agent. This gum is non-toxic and comes from a renewable natural source. The particles and gel were thoroughly characterized through using rheological measurements, UV-vis spectroscopy, nanoparticles tracking analysis, and transmission electron microscopy analysis (TEM). Antibacterial tests were carried out, confirming antimicrobial action of the silver nanoparticle-loaded gels. Furthermore, rat wound-healing models were used and demonstrated that the gels exhibited improved wound healing when compared to the base hydrogel as a control. Thus, these gels are proposed as excellent candidates for use as wound-healing treatments.

In Situ Synthesis of Silver Nanoparticles in a Hydrogel of Carboxymethyl Cellulose with Phthalated-Cashew Gum as a Promising Antibacterial and Healing Agent

PubMed Central

Lustosa, Ana Karina Marques Fortes; de Jesus Oliveira, Antônia Carla; Quelemes, Patrick Veras; Plácido, Alexandra; da Silva, Francilene Vieira; Oliveira, Irisdalva Sousa; de Almeida, Miguel Peixoto; Amorim, Adriany das Graças Nascimento; Delerue-Matos, Cristina; de Oliveira, Rita de Cássia Meneses; da Silva, Durcilene Alves

2017-01-01

Silver nanoparticles have been shown to possess considerable antibacterial activity, but in vivo applications have been limited due to the inherent, but low, toxicity of silver. On the other hand, silver nanoparticles could provide cutaneous protection against infection, due to their ability to liberate silver ions via a slow release mechanism, and their broad-spectrum antimicrobial action. Thus, in this work, we describe the development of a carboxymethyl cellulose-based hydrogel containing silver nanoparticles. The nanoparticles were prepared in the hydrogel in situ, utilizing two variants of cashew gum as a capping agent, and sodium borohydride as the reducing agent. This gum is non-toxic and comes from a renewable natural source. The particles and gel were thoroughly characterized through using rheological measurements, UV-vis spectroscopy, nanoparticles tracking analysis, and transmission electron microscopy analysis (TEM). Antibacterial tests were carried out, confirming antimicrobial action of the silver nanoparticle-loaded gels. Furthermore, rat wound-healing models were used and demonstrated that the gels exhibited improved wound healing when compared to the base hydrogel as a control. Thus, these gels are proposed as excellent candidates for use as wound-healing treatments. PMID:29137157

Pathogenic bacteria carried by companion animals and their susceptibility to antibacterial agents.

PubMed

Buma, Ryoko; Maeda, Takuya; Kamei, Masaharu; Kourai, Hiroki

2006-03-01

Results of the investigation showed that there was a difference in the bacteria isolated from dogs, cats and their living environment. The number and species isolated from the hair and front paw samples from dogs kept outdoors and from cats were greater and more varied than those from the samples from dogs kept indoors. Staphylococcus, Micrococcus and Bacillus were frequently detected from skin surfaces. On the other hand, Escherichia, Pseudomonas, Proteus and others were detected on each sampling area on dogs kept outdoors and on cats. About 60% of the bacteria commonly causes infectious diseases and carries a risk of food poisoning. Moreover, Pasteurella multocida, which causes pasteurellasis, a kind of zoonosis, was isolated from dogs and cats. These pathogenic bacteria were transmitted from animals to humans by direct contact. This result suggests that direct contact with dogs and cats and contact with aerosols can possibly transmit infectious diseases. Most of the isolates (75.9%, 60/79) were resistant to antibacterial agents. We then investigated the effect of household detergents and pet care deodorant sprays containing antibacterial agents on isolates from dogs and cats. They were effective in preventing the transmission of pathogens from dogs and cats to humans.

[Special characteristics of antibiotic therapy in the elderly].

PubMed

Stock, Ingo

2012-03-01

The ever-increasing proportion of elderly people in the general population represents physicians and pharmacists with new challenges. Older people suffer more frequently than younger persons from bacterial diseases, and they have a higher tendency to develop more severe or progressive forms of these illnesses. Bacterial diseases of the urinary tract, respiratory tract, skin and soft tissues are especially common in old age. In general, most antibacterial agents are also promising agents for the therapy of bacterial diseases in the elderly. Prior to initiating therapy, however, the modified organ functions of the elderly have to be considered carefully. Depending on the individual and the antibacterial agent, a dose adjustment may be necessary. To reduce the high mortality rate characteristic for many infectious diseases in the elderly, antibacterial therapy ought to be carefully calculated and initiated as quickly as possible. It has to be born in mind that some side effects of antibiotics are more common and more severe in old age. Since older people often take several drugs simultaneously, the probability for the occurrence of side effects and drug interactions in this population is greatly increased. Significant compliance problems may also arise.

Evaluation of the antibacterial activity of a conventional orthodontic composite containing silver/hydroxyapatite nanoparticles.

PubMed

Sodagar, Ahmad; Akhavan, Azam; Hashemi, Ehsan; Arab, Sepideh; Pourhajibagher, Maryam; Sodagar, Kosar; Kharrazifard, Mohammad Javad; Bahador, Abbas

2016-12-01

One of the most important complications of fixed orthodontic treatment is the formation of white spots which are initial carious lesions. Addition of antimicrobial agents into orthodontic adhesives might be a wise solution for prevention of white spot formation. The aim of this study was to evaluate the antibacterial properties of a conventional orthodontic adhesive containing three different concentrations of silver/hydroxyapatite nanoparticles. One hundred and sixty-two Transbond XT composite discs containing 0, 1, 5, and 10 % silver/hydroxyapatite nanoparticles were prepared and sterilized. Antibacterial properties of these composite groups against Streptococcus mutans, Lactobacillus acidophilus, and Streptococcus sanguinis were investigated using three different antimicrobial tests. Disk agar diffusion test was performed to assess the diffusion of antibacterial agent on brain heart infusion agar plate by measuring bacterial growth inhibition zones. Biofilm inhibition test showed the antibacterial capacity of composite discs against resistant bacterial biofilms. Antimicrobial activity of eluted components from composite discs was investigated by comparing the viable counts of bacteria after 3, 15, and 30 days. Composite discs containing 5 and 10 % silver/hydroxyapatite nanoparticles were capable of producing growth inhibition zones for all bacterial types. Results of biofilm inhibition test showed that all of the study groups reduced viable bacterial count in comparison to the control group. Antimicrobial activity of eluted components from composite discs was immensely diverse based on the bacterial type and the concentration of nanoparticles. Transbond XT composite discs containing 5 and 10 % silver/hydroxyapatite nanoparticles produce bacterial growth inhibition zones and show antibacterial properties against biofilms.

Tannic acid-mediated green synthesis of antibacterial silver nanoparticles.

PubMed

Kim, Tae Yoon; Cha, Song-Hyun; Cho, Seonho; Park, Youmie

2016-04-01

The search for novel antibacterial agents is necessary to combat microbial resistance to current antibiotics. Silver nanoparticles (AgNPs) have been reported to be effective antibacterial agents. Tannic acid is a polyphenol compound from plants with antioxidant and antibacterial activities. In this report, AgNPs were prepared from silver ions by tannic acid-mediated green synthesis (TA-AgNPs). The reaction process was facile and involved mixing both silver ions and tannic acid. The absorbance at 423 nm in the UV-Visible spectra demonstrated that tannic acid underwent a reduction reaction to produce TA-AgNPs from silver ions. The synthetic yield of TA-AgNPs was 90.5% based on inductively coupled plasma mass spectrometry analysis. High-resolution transmission electron microscopy and atomic force microscopy images indicated that spherical-shaped TA-AgNPs with a mean particle size of 27.7-46.7 nm were obtained. Powder high-resolution X-ray diffraction analysis indicated that the TA-AgNP structure was face-centered cubic with a zeta potential of -27.56 mV. The hydroxyl functional groups of tannic acid contributed to the synthesis of TA-AgNPs, which was confirmed by Fourier transform infrared spectroscopy. The in vitro antibacterial activity was measured using the minimum inhibitory concentration (MIC) method. The TA-AgNPs were more effective against Gram-negative bacteria than Gram-positive bacteria. The MIC for the TA-AgNPs in all of the tested strains was in a silver concentration range of 6.74-13.48 μg/mL. The tannic acid-mediated synthesis of AgNPs afforded biocompatible nanocomposites for antibacterial applications.

Antibacterial properties and mechanisms of gold-silver nanocages

NASA Astrophysics Data System (ADS)

Wang, Yulan; Wan, Jiangshan; Miron, Richard J.; Zhao, Yanbin; Zhang, Yufeng

2016-05-01

Despite the number of antibiotics used in routine clinical practice, bacterial infections continue to be one of the most important challenges faced in humans. The main concerns arise from the continuing emergence of antibiotic-resistant bacteria and the difficulties faced with the pharmaceutical development of new antibiotics. Thus, advancements in the avenue of novel antibacterial agents are essential. In this study, gold (Au) was combined with silver (Ag), a well-known antibacterial material, to form silver nanoparticles producing a gold-silver alloy structure with hollow interiors and porous walls (gold-silver nanocage). This novel material was promising in antibacterial applications due to its better biocompatibility than Ag nanoparticles, potential in photothermal effects and drug delivery ability. The gold-silver nanocage was then tested for its antibacterial properties and the mechanism involved leading to its antibacterial properties. This study confirms that this novel gold-silver nanocage has broad-spectrum antibacterial properties exerting its effects through the destruction of the cell membrane, production of reactive oxygen species (ROS) and induction of cell apoptosis. Therefore, we introduce a novel gold-silver nanocage that serves as a potential nanocarrier for the future delivery of antibiotics.

The investigation of antibacterial activity of selected native plants from North of Iran.

PubMed

Koohsari, H; Ghaemi, E A; Sadegh Sheshpoli, M; Jahedi, M; Zahiri, M

2015-01-01

Plant derived products have been used for medicinal purposes during centuries. Bacterial resistance to currently used antibiotics has become a concern to public health. The development of bacterial super resistant strains has resulted in the currently used antibiotic agents failing to end many bacterial infections. For this reason, the search is ongoing for new antimicrobial agents, both by the design and by the synthesis of new agents, or through the search of natural sources for yet undiscovered antimicrobial agents. Herbal medications in particular have seen a revival of interest due to a perception that there is a lower incidence of adverse reactions to plant preparations compared to synthetic pharmaceuticals. Coupled with the reduced costs of plant preparations, this makes the search for natural therapeutics an attractive option. This research was carried out to assess the antibacterial activity aqueous and ethanolic extracts of six Azadshahr township Native plants in north of Iran against six species of pathogen bacteria by using three methods of Disk diffusion, Well method and MBC. The results of this research indicated that the effect of ethanol extracts were more than aqueous extract and among six plants, Lippia citriodora and Plantago major ethanol extract had the most antibacterial activity in any of the three methods. Gram-positive bacteria were more sensitive than gram-negative bacteria. Staphylococcus epidermidis and Staphylococcus aureus were the most susceptible Gram-positive bacteria.

Combined effect of zinc ions and cationic antibacterial agents on intraoral volatile sulphur compounds (VSC).

PubMed

Young, A; Jonski, G; Rölla, G

2003-08-01

Volatile sulphur compounds (VSC) are major components of oral malodour. As both zinc ions and cationic antibacterial agents inhibit the formation of oral VSC, this study aimed to determine whether these agents combined have synergistic anti-VSC actions. Baseline oral VSC measurements of mouth air from 10 volunteers following cysteine rinsing (6mM, pH 7.2) were obtained using gas chromatography (GC). Subjects rinsed for 1 min with 10ml of the test solutions, 0.3% zinc acetate (Zn), 0.025% chlorhexidine (CHX), 0.025% cetyl pyridinium (CPC), and the combinations Zn+CHX and Zn+CPC. Cysteine rinses were repeated at 1h, 2h and 3h and VSC measurements recorded. Three subjects rinsed with the Zn+CHX combination and fasted for 9h, undergoing cysteine rinses and VSC measurements at 3h intervals. 10 microl of the test solutions were also added to 1ml aliquots of human whole saliva (n=8). Following incubation at 37 degrees C for 24h VSC levels in the saliva headspace were measured by GC. Inhibition of VSC formation and the fractional inhibitory index indicating synergy were calculated. Zn+CHX mouthrinse had a synergistic anti-VSC effect, and was effective for at least 9h. Zn+CPC mouthrinse was less effective. Both combinations showed a synergistic inhibiting effect in-vitro. Synergy between Zn and the antibacterial agents confirms different mechanisms of operation.

In vitro evaluation of the antibacterial activity of Arctium lappa as a phytotherapeutic agent used in intracanal dressings.

PubMed

Gentil, Marcelo; Pereira, Juliana Vianna; Sousa, Yara T Corrêa Silva; Pietro, Rosimeire; Neto, Manoel D Sousa; Vansan, Luiz Pascoal; de Castro França, Suzelei

2006-03-01

The discovery of natural biocomponents from plants with antibacterial activity on endodontic microbiota may lead to new therapies. This study evaluated the antibacterial activity of a phytotherapeutic agent prepared from an ethyl acetate fraction (AcOEt) extracted from Arctium lappa. This agent was compared with calcium hydroxide as an intracanal dressing. Twenty-seven maxillary canines were instrumented, sterilized and inoculated with a mixed bacterial suspension of Pseudomonas aeruginosa, Escherichia coli, Lactobacillus acidophilus, Streptococcus mutans and Candida albicans. The teeth were divided into three groups and their canals filled with: group 1, calcium hydroxide and propylene glycol; group 2, a paste containing AcOEt fraction of A. lappa and propylene glycol; group 3, propylene glycol (control). At 7, 14 and 30 days, three teeth from each group were opened and a paper point was placed in the root canal for 5 min. The paper points were transferred to Petri dishes with Brain Heart Infusion (BHI). The bacterial growth was classified. Mild bacterial growth was found in group 1 at all time intervals; in group 2 there was severe growth at 7 days, but no growth at 14 and 30 days. The phytotherapeutic agent extracted from an AcOEt fraction of A. lappa inhibited the growth of all the microorganisms in this study. Copyright 2006 John Wiley & Sons, Ltd.

Antibacterial activity of 3-methylbenzo[d]thiazol-methylquinolinium derivatives and study of their action mechanism.

PubMed

Sun, Ning; Du, Ruo-Lan; Zheng, Yuan-Yuan; Guo, Qi; Cai, Sen-Yuan; Liu, Zhi-Hua; Fang, Zhi-Yuan; Yuan, Wen-Chang; Liu, Ting; Li, Xiao-Mei; Lu, Yu-Jing; Wong, Kwok-Yin

2018-12-01

The increasing incidence of multidrug resistant bacterial infection renders an urgent need for the development of new antibiotics. To develop small molecules disturbing FtsZ activity has been recognized as promising approach to search for antibacterial of high potency systematically. Herein, a series of novel quinolinium derivatives were synthesized and their antibacterial activities were investigated. The compounds show strong antibacterial activities against different bacteria strains including MRSA, VRE and NDM-1 Escherichia coli. Among these derivatives, a compound bearing a 4-fluorophenyl group (A2) exhibited a superior antibacterial activity and its MICs to the drug-resistant strains are found lower than those of methicillin and vancomycin. The biological results suggest that these quinolinium derivatives can disrupt the GTPase activity and dynamic assembly of FtsZ, and thus inhibit bacterial cell division and then cause bacterial cell death. These compounds deserve further evaluation for the development of new antibacterial agents targeting FtsZ.

Pterostilbene, a Methoxylated Resveratrol Derivative, Efficiently Eradicates Planktonic, Biofilm, and Intracellular MRSA by Topical Application

PubMed Central

Yang, Shih-Chun; Tseng, Chih-Hua; Wang, Pei-Wen; Lu, Po-Liang; Weng, Yi-Han; Yen, Feng-Lin; Fang, Jia-You

2017-01-01

Pterostilbene is a methoxylated derivative of resveratrol originated from natural sources. We investigated the antibacterial activity of pterostilbene against drug-resistant Staphylococcus aureus and the feasibility of using it to treat cutaneous bacteria. The antimicrobial effect was evaluated using an in vitro culture model and an in vivo mouse model of cutaneous infection. The minimum inhibitory concentration (MIC) assay demonstrated a superior biocidal activity of pterostilbene compared to resveratrol (8~16-fold) against methicillin-resistant S. aureus (MRSA) and clinically isolated vancomycin-intermediate S. aureus (VISA). Pterostilbene was found to reduce MRSA biofilm thickness from 18 to 10 μm as detected by confocal microscopy. Pterostilbene showed minimal toxicity to THP-1 cells and was readily engulfed by the macrophages, facilitating the eradication of intracellular MRSA. Pterostilbene exhibited increased skin absorption over resveratrol by 6-fold. Topical pterostilbene application improved the abscess formation produced by MRSA by reducing the bacterial burden and ameliorating the skin architecture. The potent anti-MRSA capability of pterostilbene was related to bacterial membrane leakage, chaperone protein downregulation, and ribosomal protein upregulation. This mechanism of action was different from that of resveratrol according to proteomic analysis and molecular docking. Pterostilbene has the potential to serve as a novel class of topically applied agents for treating MRSA infection in the skin while demonstrating less toxicity to mammalian cells. PMID:28659908

Preparation of Calcium Carbonate (from Shellfish)/Magnesium Oxide Composites as an Antibacterial Agent

NASA Astrophysics Data System (ADS)

Jannah, Z.; Mubarok, H.; Syamsiyah, F.; Putri, A. A. H.; Rohmawati, L.

2018-05-01

We have performed research on antibacterial substance from a natural substance, one of them is calcite from shellfish (Anadara granosa) in Kenjeran Beach Surabaya. This calcite is composed of magnesium oxide using PEG 4000 (Polyethylene glycol) as a solvent and then heated at 800 °C for 30 minutes. Weight variety of calcite used was 80% wt, 85% wt, and 90 wt%. Subsequently, that composites characterized using XRD, antibacterial activity test (Escherichia coli and Staphylococcus aureus), and SEM. The result of antibacterial assay shows that composite of CaCO3/MgO with 80% wt composition have the best activity inhibitory of 31,96 mm for Escherichia coli bacteria and 32.26 mm for Staphylococcus aureus bacteria.

Preparation and antibacterial activity of oligosaccharides derived from dandelion.

PubMed

Qian, Li; Zhou, Yan; Teng, Zhaolin; Du, Chun-Ling; Tian, Changrong

2014-03-01

In this study, we prepared oligosaccharides from dandelion (Taraxacum officinale) by hydrolysis with hydrogen peroxide (H2O2) and investigated their antibacterial activity. The optimum hydrolysis conditions, as determined using the response surface methodology, were as follows: reaction time, 5.12h; reaction temperature, 65.53 °C and H2O2 concentration, 3.16%. Under these conditions, the maximum yield of the oligosaccharides reached 25.43%. The sugar content in the sample was 96.8%, and the average degree of polymerisation was approximately 9. The oligosaccharides showed high antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus, indicating that dandelion-derived oligosaccharides have the potential to be used as antibacterial agents. Copyright © 2013 Elsevier B.V. All rights reserved.

Bacterial skin infections: management of common streptococcal and stapylococcal lesions.

PubMed

Witkowski, J A; Parish, L C

1982-10-01

Skin infection occurs in any age-group, sex, and race but is particularly common in children. It is usually minor, but may indicate underlying systemic disease or may lead to systemic infection. Streptococci and staphylococci are common causes. Group A beta-hemolytic streptococci account for the majority of streptococcal infections in man. Infection most often involves the lower extremities and produces spreading erythema and necrosis but little purulence. Staphylococcal infections most commonly involve the face, the hair follicles and eccrine sweat ducts being the initial sites. Lesions appear as bullae and pustules with a narrow rim of erythema. Intense cellulitis surrounding the lesions usually points to a virulent, penicillin-resistant strain of Staphylococcus. Treatment of both types of infection consists of cleansing with antibacterial agents, removal of crusts, application of warm compresses, and use of topical or systemic antibiotics, depending on the severity of the infection and the type of pyoderma involved.

Synthesis and in vitro antibacterial activity of new steroidal thiosemicarbazone derivatives.

PubMed

Khan, Salman Ahmad; Kumar, Praveen; Joshi, Rajkumar; Iqbal, Prince F; Saleem, Kishwar

2008-09-01

We investigated the antibacterial activity of some new steroidal thiosemicarbazone derivatives, prepared from the reaction of cholest-5-en-7-one with thiosemicarbazides, in ethanol in the presence of a few drops of HCl at 80 degrees C in high yield. All the compounds have been characterized by means of elemental analyses, IR, 1H NMR and mass spectroscopic data, to find an effective antibacterial agent. The antibacterial activity was first tested in vitro by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) of compounds was determined. The results showed that the steroidal thiosemicarbazones derivatives inhibit growth of both types of the bacteria (Gram-positive and Gram-negative). The acetoxy and chloro derivatives of cyclopentyl and cyclohexyl amine thiosemicarbazones were found to have more antibacterial activity than the other derivatives.

Low Cost CaTiO3 Perovskite Synthesized from Scallop (Anadara granosa) Shell as Antibacterial Ceramic Material

NASA Astrophysics Data System (ADS)

Fatimah, Is; Nur Ilahi, Rico; Pratami, Rismayanti

2018-01-01

Research on perovskite CaTiO3 synthesis from scallop (Anadara granosa) shell and its test as material for antibacterial ceramic application have been conducted. The synthesis was performed by calcium extraction from the scallop shell followed by solid-solid reaction of obtained calcium with TiO2. Physicochemical character of the perovskite wasstudied by measurement of crystallinity using x-ray diffraction (XRD), diffuse-reflectance UV Visible spectrophotometry, scanning electrone microscope-energy dispersive x-ray (SEM-EDX) and Fourier-Transform InfraRed. Considering the future application of the perovskite as antibacterial agent, laboratory test of the peroskite as material in antibacterial ceramic preparation was also conducted. Result of research indicated that perovskite formation was obtained and the material demonstrated photocatalytic activity as identified by band gap energy (Eg) value. The significant activity was also reflected by the antibacterial action of formed ceramic.

Oxidative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa.

PubMed

Gurunathan, Sangiliyandi; Han, Jae Woong; Dayem, Ahmed Abdal; Eppakayala, Vasuki; Kim, Jin-Hoi

2012-01-01

Graphene holds great promise for potential use in next-generation electronic and photonic devices due to its unique high carrier mobility, good optical transparency, large surface area, and biocompatibility. The aim of this study was to investigate the antibacterial effects of graphene oxide (GO) and reduced graphene oxide (rGO) in Pseudomonas aeruginosa. In this work, we used a novel reducing agent, betamercaptoethanol (BME), for synthesis of graphene to avoid the use of toxic materials. To uncover the impacts of GO and rGO on human health, the antibacterial activity of two types of graphene-based material toward a bacterial model P. aeruginosa was studied and compared. The synthesized GO and rGO was characterized by ultraviolet-visible absorption spectroscopy, particle-size analyzer, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Further, to explain the antimicrobial activity of graphene oxide and reduced graphene oxide, we employed various assays, such as cell growth, cell viability, reactive oxygen species generation, and DNA fragmentation. Ultraviolet-visible spectra of the samples confirmed the transition of GO into graphene. Dynamic light-scattering analyses showed the average size among the two types of graphene materials. X-ray diffraction data validated the structure of graphene sheets, and high-resolution scanning electron microscopy was employed to investigate the morphologies of prepared graphene. Raman spectroscopy data indicated the removal of oxygen-containing functional groups from the surface of GO and the formation of graphene. The exposure of cells to GO and rGO induced the production of superoxide radical anion and loss of cell viability. Results suggest that the antibacterial activities are contributed to by loss of cell viability, induced oxidative stress, and DNA fragmentation. The antibacterial activities of GO and rGO against P. aeruginosa were compared. The loss of P. aeruginosa viability increased in a dose- and time-dependent manner. Exposure to GO and rGO induced significant production of superoxide radical anion compared to control. GO and rGO showed dose-dependent antibacterial activity against P. aeruginosa cells through the generation of reactive oxygen species, leading to cell death, which was further confirmed through resulting nuclear fragmentation. The data presented here are novel in that they prove that GO and rGO are effective bactericidal agents against P. aeruginosa, which would be used as a future antibacterial agent.

Oxidative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa

PubMed Central

Gurunathan, Sangiliyandi; Han, Jae Woong; Dayem, Ahmed Abdal; Eppakayala, Vasuki; Kim, Jin-Hoi

2012-01-01

Background Graphene holds great promise for potential use in next-generation electronic and photonic devices due to its unique high carrier mobility, good optical transparency, large surface area, and biocompatibility. The aim of this study was to investigate the antibacterial effects of graphene oxide (GO) and reduced graphene oxide (rGO) in Pseudomonas aeruginosa. In this work, we used a novel reducing agent, betamercaptoethanol (BME), for synthesis of graphene to avoid the use of toxic materials. To uncover the impacts of GO and rGO on human health, the antibacterial activity of two types of graphene-based material toward a bacterial model P. aeruginosa was studied and compared. Methods The synthesized GO and rGO was characterized by ultraviolet-visible absorption spectroscopy, particle-size analyzer, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Further, to explain the antimicrobial activity of graphene oxide and reduced graphene oxide, we employed various assays, such as cell growth, cell viability, reactive oxygen species generation, and DNA fragmentation. Results Ultraviolet-visible spectra of the samples confirmed the transition of GO into graphene. Dynamic light-scattering analyses showed the average size among the two types of graphene materials. X-ray diffraction data validated the structure of graphene sheets, and high-resolution scanning electron microscopy was employed to investigate the morphologies of prepared graphene. Raman spectroscopy data indicated the removal of oxygen-containing functional groups from the surface of GO and the formation of graphene. The exposure of cells to GO and rGO induced the production of superoxide radical anion and loss of cell viability. Results suggest that the antibacterial activities are contributed to by loss of cell viability, induced oxidative stress, and DNA fragmentation. Conclusion The antibacterial activities of GO and rGO against P. aeruginosa were compared. The loss of P. aeruginosa viability increased in a dose- and time-dependent manner. Exposure to GO and rGO induced significant production of superoxide radical anion compared to control. GO and rGO showed dose-dependent antibacterial activity against P. aeruginosa cells through the generation of reactive oxygen species, leading to cell death, which was further confirmed through resulting nuclear fragmentation. The data presented here are novel in that they prove that GO and rGO are effective bactericidal agents against P. aeruginosa, which would be used as a future antibacterial agent. PMID:23226696

Allergic, Immunological and Infectious Disease Problems in Aerospace Medicine Held in Rome, Italy on 21 - 25 October 1991 (Les Problemes Causes par les Maladies Allergiques, Immunologiques et Contagieuses en Mdecine Aerospatiale).

DTIC Science & Technology

1992-04-01

whose lymphocytes displayed, at the identified. When assays for antibacterial activity time of lowest immune responses, a surface IL2Ra were performed...with these two agents SSD demon- level around 50% of the first day level (Figure 5), strated superior antibacterial activity in in vitro tests the...day At day 30, a significative increase of direct antibacterial activity 0 and 28. The second group was treated with Ty2la (Neotif, Scla- was observed

Novel dental adhesive containing antibacterial agents and calcium phosphate nanoparticles

PubMed Central

Melo, Mary Anne S.; Cheng, Lei; Weir, Michael D.; Hsia, Ru-ching; Rodrigues, Lidiany K. A.; Xu, Hockin H. K.

2013-01-01

Secondary caries remains the main reason for dental restoration failure. Replacement of failed restorations accounts for 50-70% of all restorations performed. Antibacterial adhesives could inhibit biofilm acids at tooth-restoration margins, and calcium phosphate (CaP) ions could remineralize tooth lesions. The objectives of this study were to: (1) incorporate nanoparticles of silver (NAg), quaternary ammonium dimethacrylate (QADM), and nanoparticles of amorphous calcium phosphate (NACP) into bonding agent; and (2) investigate their effects on dentin bonding and microcosm biofilms. An experimental primer was made with pyromellitic glycerol dimethacrylate (PMGDM) and 2-hydroxyethyl methacrylate (HEMA). An adhesive was made with bisphenol-A-glycerolate dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA). NAg was incorporated into primer at 0.1wt%. The adhesive contained 0.1% NAg and 10% QADM, and 0-40% NACP. Incorporating NAg into primer and NAg-QADM-NACP into adhesive did not adversely affect dentin bond strength (p>0.1). SEM showed numerous resin tags, and TEM revealed NAg and NACP in dentinal tubules. Viability of human saliva microcosm biofilms on primer/adhesive/composite disks was substantially reduced via NAg and QADM. Metabolic activity, lactic acid, and colony-forming units of biofilms were much lower on the new bonding agents than control (p<0.05). In conclusion, novel dental bonding agents containing NAg, QADM and NACP were developed with the potential to kill residual bacteria in the tooth cavity and inhibit the invading bacteria along tooth-restoration margins, with NACP to remineralize tooth lesions. The novel method of combining antibacterial agents (NAg and QADM) with remineralizing agent (NACP) may have wide applicability to other adhesives for caries inhibition. PMID:23281264

Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease.

PubMed

Frikha-Gargouri, Olfa; Ben Abdallah, Dorra; Bhar, Ilhem; Tounsi, Slim

2017-01-01

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes ( sfp, ituC and bmyB ) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight ( p = 0.000) and the antibacterial activity in vitro ( p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol ( p = 0.004) and the reduction in gall weight ( p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo . Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens . These strains were found to produce either surfactin or surfactin and iturin lipopeptides. In conclusion, our study presented a new and effective method to evaluate the biocontrol ability of antagonistic Bacillus strains against crown gall disease that could increase the efficiency of screening method of biocontrol agents. Besides, the selected strains could be used as novel biocontrol agents against pathogenic Agrobacterium tumefaciens strains.

Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease

PubMed Central

Frikha-Gargouri, Olfa; Ben Abdallah, Dorra; Bhar, Ilhem; Tounsi, Slim

2017-01-01

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes (sfp, ituC and bmyB) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight (p = 0.000) and the antibacterial activity in vitro (p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol (p = 0.004) and the reduction in gall weight (p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo. Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens. These strains were found to produce either surfactin or surfactin and iturin lipopeptides. In conclusion, our study presented a new and effective method to evaluate the biocontrol ability of antagonistic Bacillus strains against crown gall disease that could increase the efficiency of screening method of biocontrol agents. Besides, the selected strains could be used as novel biocontrol agents against pathogenic Agrobacterium tumefaciens strains. PMID:28855909

Optimization of the central linker of dicationic bis-benzimidazole anti-MRSA and anti-VRE agents.

PubMed

Hu, Laixing; Kully, Maureen L; Boykin, David W; Abood, Norman

2009-07-01

A series of bis-benzimidazole diamidine compounds containing different central linkers has been synthesized and evaluated for in vitro antibacterial activities, including drug-resistant bacterial strains. Seven compounds have shown potent antibacterial activities. The anti-MRSA and anti-VRE activities of compound 1h were more potent than that of the lead compound 1a and vancomycin.

Antibacterial activity, surface roughness, flexural strength, and solubility of conventional luting cements containing chlorhexidine diacetate/cetrimide mixtures.

PubMed

Korkmaz, Fatih Mehmet; Tüzüner, Tamer; Baygin, Ozgul; Buruk, Celal Kurtulus; Durkan, Rukiye; Bagis, Bora

2013-08-01

The failure of fixed dental restorations is commonly associated with caries. The use of conventional luting cements containing antibacterial agents may overcome this problem. The purpose of this study was to evaluate the antibacterial activity (ABA), surface roughness (Ra), flexural strength (FS), and solubility (SL) patterns of the conventional dental luting cements zinc phosphate (ZP), zinc polycarboxylate (PC), and glass ionomer (GIC) after the addition of 5% chlorhexidine diacetate/cetrimide (CHX+CT). Antibacterial agents with a total concentration of 5% (2.5% CHX+2.5% CT) were added to antibacterial agent-free conventional luting cement powders (ZPC, PCC, and GICC) and designated as experimental groups (ZPE, PCE, and GICE). ABA against Streptococcus mutans (SM) and Lactobacillus casei (LB) was examined by using the agar diffusion test method. Ra, FS, and SL values were obtained after storage in distilled water at 37°C for 24 hours. The Kruskal-Wallis and Mann Whitney U with Bonferroni correction tests were used to test for agar diffusion (α=.05) and 2-way ANOVA and Fisher Least Significant Difference (LSD) test were used to measure Ra, FS, and SL (α=.05). The control groups exhibited limited ABA. With the exception of PCE>PCC on day 1 for SM, all experimental groups showed significantly greater and longer-lasting protection against SM and LB bacteria for up to 180 days than their controls (P<.05). Ra values decreased (ZPC>ZPE; P>.05, PCC>PCE; P<.05) except that GICE>GICC (P>.05) when compared with their individual controls. Control groups exhibited higher FS values than did the experimental groups (ZPC>ZPE; P<.05, PCC>PCE; P<.05, GICC>GICE; P>.05). The experimental groups exhibited higher solubilities than did their controls in the ZPC (P>.05) and GICC groups (P<.05) but were lower in PCC group (P<.05). Incorporating a 5% CHX+CT mixture into conventional dental luting cements and altering their Ra, FS, and SL values may provide greater antibacterial protection against SM and LB. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Cotton textiles modified with citric acid as efficient anti-bacterial agent for prevention of nosocomial infections

PubMed Central

Bischof Vukušić, Sandra; Flinčec Grgac, Sandra; Budimir, Ana; Kalenić, Smilja

2011-01-01

Aim To study the antimicrobial activity of citric acid (CA) and sodium hypophosphite monohydrate (SHP) against gram-positive and gram-negative bacteria, and to determine the influence of conventional and microwave thermal treatments on the effectiveness of antimicrobial treatment of cotton textiles. Method Textile material was impregnated with CA and SHP solution and thermally treated by either conventional or microwave drying/curing treatment. Antibacterial effectiveness was tested according to the ISO 20743:2009 standard, using absorption method. The surfaces were morphologically observed by scanning electron microscopy, while physical characteristics were determined by wrinkle recovery angles method (DIN 53 891), tensile strength (DIN 53 837), and whiteness degree method (AATCC 110-2000). Results Cotton fabric treated with CA and SHP showed significant antibacterial activity against MRSA (6.38 log10 treated by conventional drying and 6.46 log10 treated by microwave drying before washing, and 6.90 log10 and 7.86 log10, respectively, after 1 cycle of home domestic laundering washing [HDLW]). Antibacterial activity was also remarkable against S. aureus (4.25 log10 by conventional drying, 4.58 log10 by microwave drying) and against P. aeruginosa (1.93 log10 by conventional and 4.66 log10 by microwave drying). Antibacterial activity against P. aeruginosa was higher in samples subjected to microwave drying/curing than in those subjected to conventional drying/curing. As expected, antibacterial activity was reduced after 10 HDLW cycles but the compound was still effective. The surface of the untreated cotton polymer was smooth, while minor erosion stripes appeared on the surfaces treated with antimicrobial agent, and long and deep stripes were found on the surface of the washed sample. Conclusion CA can be used both for the disposable (non-durable) materials (gowns, masks, and cuffs for blood pressure measurement) and the materials that require durability to laundering. The current protocols and initiatives in infection control could be improved by the use of antimicrobial agents applied on cotton carbohydrate polymer. PMID:21328723

4-Substituted thieno[2,3-d]pyrimidines as potent antibacterial agents: Rational design, microwave-assisted synthesis, biological evaluation and molecular docking studies.

PubMed

Gill, Rupinder K; Singh, Harpreet; Raj, Tilak; Sharma, Anuradha; Singh, Gagandeep; Bariwal, Jitender

2017-12-01

In an attempt to discover a new class of antibacterial agents with improved efficacy and to overcome the drug-resistant problems, some novel 4-substituted thieno[2,3-d]pyrimidines have been synthesized via microwave-assisted methodology and evaluated for their in vitro antibacterial activity against various pathogenic bacterial strains. Compounds 12b and 13c showed the promising inhibitory potencies against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli with MICs ranging from 2 to 10 μg/ml. Compound 13c was also found to be highly potent against methicillin-resistant S. aureus (MRSA) with MIC value of 4 μg/ml. Docking simulation studies have been performed to unravel the mode of action and association study indicate the binding of potent compounds with DHPS enzyme. In silico ADME studies suggest the drug-like characteristics of the potent compounds. © 2017 John Wiley & Sons A/S.

Novel Hybrid Virtual Screening Protocol Based on Molecular Docking and Structure-Based Pharmacophore for Discovery of Methionyl-tRNA Synthetase Inhibitors as Antibacterial Agents

PubMed Central

Liu, Chi; He, Gu; Jiang, Qinglin; Han, Bo; Peng, Cheng

2013-01-01

Methione tRNA synthetase (MetRS) is an essential enzyme involved in protein biosynthesis in all living organisms and is a potential antibacterial target. In the current study, the structure-based pharmacophore (SBP)-guided method has been suggested to generate a comprehensive pharmacophore of MetRS based on fourteen crystal structures of MetRS-inhibitor complexes. In this investigation, a hybrid protocol of a virtual screening method, comprised of pharmacophore model-based virtual screening (PBVS), rigid and flexible docking-based virtual screenings (DBVS), is used for retrieving new MetRS inhibitors from commercially available chemical databases. This hybrid virtual screening approach was then applied to screen the Specs (202,408 compounds) database, a structurally diverse chemical database. Fifteen hit compounds were selected from the final hits and shifted to experimental studies. These results may provide important information for further research of novel MetRS inhibitors as antibacterial agents. PMID:23839093

The frequency of antibiotic-resistant bacteria in homes differing in their use of surface antibacterial agents.

PubMed

Marshall, Bonnie M; Robleto, Eduardo; Dumont, Theresa; Levy, Stuart B

2012-10-01

Antibacterial agents are common in household cleaning and personal care products, but their long-range impacts on commensal and pathogenic household bacteria are largely unknown. In a one-time survey of 38 households from Boston, MA [19] and Cincinnati, OH [18], 13 kitchen and bathroom sites were sampled for total aerobic bacteria and screened for gram phenotype and susceptibility to six antibiotic drug families. The overall bacterial titers of both user (2 or more antibacterial cleaning or personal care products) and non-user (0 or 1 product) rooms were similar with sponges and sink drains consistently showing the highest overall titers and relatively high titers of antibiotic-resistant bacteria. The mean frequency of resistant bacteria ranged from ≤20 % to as high as 45 % and multi-drug resistance was common. However, no significant differences were noted between biocide users and non-users. The frequency of pathogen recovery was similar in both user and non-user groups.

Pseudomonas aeruginosa prevalence, antibiotic resistance and antimicrobial use in Chinese burn wards from 2007 to 2014

PubMed Central

Dou, Yi; Guo, Feng; Zhou, Zengding; Shi, Yan

2017-01-01

Objective To assess the application of antibacterial agents, alongside pathogen prevalence and Pseudomonas aeruginosa drug resistance, with the aim of understanding the impact of inappropriate antibacterial use. Methods This retrospective study assessed bacteria from wounds, catheters, blood, faeces, urine and sputum of hospitalized patients in burn wards between 2007 and 2014. The intensity of use of antibacterial agents and resistance of P. aeruginosa to common anti-Gram-negative antibiotics were measured. Results Annual detection rates of Staphylococcus aureus were significantly decreased, whereas annual detection rates of P. aeruginosa and Klebsiella pneumoniae were significantly increased. Multidrug-resistant strains of P. aeruginosa were increased. The intensity of use of some anti-Gramnegative antibiotics positively correlated with resistance rates of P. aeruginosa to similar antimicrobials. Conclusion In burn wards, more attention should be paid to P. aeruginosa and K. pneumoniae. The use of ciprofloxacin, ceftazidime and cefoperazone/sulbactam should be limited to counter the related increase in resistance levels. PMID:28443385

Combined antibacterial activity of phage lytic proteins holin and lysin from Streptococcus suis bacteriophage SMP.

PubMed

Shi, Yibo; Li, Ning; Yan, Yaxian; Wang, Hengan; Li, Yan; Lu, Chengping; Sun, Jianhe

2012-07-01

Development of novel antibacterial agents is required to control infection with multidrug-resistant Streptococcus suis. HolSMP and LySMP, the holin and lysin of S. suis serotype 2 bacteriophage, named SMP, are responsible for lysis of host cells and release of progeny phage. HolSMP and LySMP expressed in Escherichia coli BL21(DE3) exerted efficient activity at 37 °C, pH 5.2, with addition of 0.8 % β-mercaptoethanol. Lytic spectra of purified HolSMP, LySMP or HolSMP + LySMP mixture were investigated. HolSMP, exhibiting a narrow lytic spectrum, was effective against Staphylococcus aureus and Bacillus subtilis, which were insensitive to LySMP. Moreover, HolSMP was identified as a promising antibacterial agent which was able to extend the spectrum of LySMP. The data suggest that combined use of holin and lysin could be a candidate strategy for resolution of drug resistance.

Antibacterial activity of natural spices on multiple drug resistant Escherichia coli isolated from drinking water, Bangladesh

PubMed Central

2011-01-01

Background Spices traditionally have been used as coloring agents, flavoring agents, preservatives, food additives and medicine in Bangladesh. The present work aimed to find out the antimicrobial activity of natural spices on multi-drug resistant Escherichia coli isolates. Methods Anti-bacterial potentials of six crude plant extracts (Allium sativum, Zingiber officinale, Allium cepa, Coriandrum sativum, Piper nigrum and Citrus aurantifolia) were tested against five Escherichia coli isolated from potable water sources at kushtia, Bangladesh. Results All the bacterial isolates were susceptible to undiluted lime-juice. None of them were found to be susceptible against the aqueous extracts of garlic, onion, coriander, pepper and ginger alone. However, all the isolates were susceptible when subjected to 1:1:1 aqueous extract of lime, garlic and ginger. The highest inhibition zone was observed with lime (11 mm). Conclusion Natural spices might have anti-bacterial activity against enteric pathogens and could be used for prevention of diarrheal diseases. Further evaluation is necessary. PMID:21406097

Nanofabrication and characterization of PVA-organofiller/Ag nanocoatings on pMAD plasmids

NASA Astrophysics Data System (ADS)

Erdonmez, D.; Mosayyebi, S.; Erkan, K.; Salimi, K.; Nagizade, N.; Saglam, N.; Rzayev, Z. M. O.

2014-11-01

Nowadays, the most important problem in microbial researches is bacterial resistance which is carried out by DNA plasmids against antibacterial agents. The effect of antibacterial nanoparticles on bacteria is remarkable, but studies on the interactions of these particles with plasmids do not search or there are no adequate studies. We proposed that the nanoparticles, which are disrupted the self-assembled structure of plasmids, may decrease the resistance of bacteria, and therefore, increase the activity of utilized antibacterial agents. In this work, we synthesized polymer nanofiber webs samples by electrospinning technique from pure water solution of nanocomposites with different contents of silver nanoparticles, and surface morphology of nanofibers composites were characterized by SEM microscopy. Their interactions with pMAD DNA plasmids were investigated. It was demonstrated that the synthesized Ag-carrying nanohybrid composites with higher surface contacted areas were significantly inhibited the activity of plasmid DNA against bacterial resistance. Agreeing with obtained results, synthesized nanofiber coatings can be recommended for the widely applications in nanobiotechnology, nanomedicine, and bioengineering processing.

Antibacterial activity of natural spices on multiple drug resistant Escherichia coli isolated from drinking water, Bangladesh.

PubMed

Rahman, Shahedur; Parvez, Anowar Khasru; Islam, Rezuanul; Khan, Mahboob Hossain

2011-03-15

Spices traditionally have been used as coloring agents, flavoring agents, preservatives, food additives and medicine in Bangladesh. The present work aimed to find out the antimicrobial activity of natural spices on multi-drug resistant Escherichia coli isolates. Anti-bacterial potentials of six crude plant extracts (Allium sativum, Zingiber officinale, Allium cepa, Coriandrum sativum, Piper nigrum and Citrus aurantifolia) were tested against five Escherichia coli isolated from potable water sources at kushtia, Bangladesh. All the bacterial isolates were susceptible to undiluted lime-juice. None of them were found to be susceptible against the aqueous extracts of garlic, onion, coriander, pepper and ginger alone. However, all the isolates were susceptible when subjected to 1:1:1 aqueous extract of lime, garlic and ginger. The highest inhibition zone was observed with lime (11 mm). Natural spices might have anti-bacterial activity against enteric pathogens and could be used for prevention of diarrheal diseases. Further evaluation is necessary.

Isobolographic Analysis of Pharmacodynamic Interactions between Antifungal Agents and Ciprofloxacin against Candida albicans and Aspergillus fumigatus▿

PubMed Central

Stergiopoulou, Theodouli; Meletiadis, Joseph; Sein, Tin; Papaioannidou, Paraskevi; Tsiouris, Ioannis; Roilides, Emmanuel; Walsh, Thomas J.

2008-01-01

Patients suffering from invasive mycoses often receive concomitant antifungal therapy and antibacterial agents. Assessment of pharmacodynamic interactions between antifungal and antibacterial agents is complicated by the absence of a common antifungal end point for both agents. Ciprofloxacin has no intrinsic antifungal activity but may interact with antifungal agents, since it inhibits DNA gyrase (topoisomerase II), which is abundant in fungi. We therefore employed isobolographic analysis adapted to incorporate a nonactive agent in order to analyze the potential in vitro interaction between the fluoroquinolone ciprofloxacin and several representative antifungal agents against Candida albicans and Aspergillus fumigatus strains by using a microdilution checkerboard technique. In agreement with earlier in vitro studies, conventional fractional inhibitory concentration index analysis was unable to detect interactions between ciprofloxacin and antifungal agents. However, isobolographic analysis revealed significant pharmacodynamic interactions between antifungal agents and ciprofloxacin against C. albicans and A. fumigatus strains. Amphotericin B demonstrated concentration-dependent interactions for both species, with synergy (interaction indices, 0.14 to 0.81) observed at ciprofloxacin concentrations of <10.64 μg/ml. Synergy (interaction indices, 0.10 to 0.86) was also found for voriconazole and caspofungin against A. fumigatus. Isobolographic analysis may help to elucidate the pharmacodynamic interactions between antifungal and non-antifungal agents and to develop better management strategies against invasive candidiasis and aspergillosis. PMID:18299413

Prevention of Prespawning Mortality: Cause of Salmon Headburns and Cranial Lesions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neitzel, Duane A.; Elston, R A.; Abernethy, Cary S.

2004-06-01

This project was to undertaken to provide information about a condition known as ''headburn''. Information from the project will enable U.S. Corps of Engineers managers to make adjustments in operational procedures or facilities on the Columbia and Snake rivers to prevent loss of pre-spawning adult salmonids that migrate through the facilities. Headburn is a descriptive clinical term used by fishery biologists to describe scalping or exfoliation of skin and ulceration of underlying connective tissue and muscle, primarily of the jaw and cranial region of salmonids observed at fish passage facilities. Headburn lesions are primarily caused when fish collide with concretemore » or other structures at dams and fish passage facilities, and may be exacerbated in some fish that ''fallback'' or pass over spillways or through turbine assemblies after having passed the dam through a fish ladder. Prespawning mortality of headburned salmonids can be prevented or greatly reduced by therapeutic treatment of both hatchery and wild fish. Treatments would consist of topical application of an anti-fungal agent, injection of replacement plasma electrolytes into the peritoneal cavity, and injection of a broad-spectrum antibacterial agent at fish passage and trapping facilities or hatcheries.« less

Honey: A Potential Therapeutic Agent for Managing Diabetic Wounds

PubMed Central

Islam, Md. Asiful; Gan, Siew Hua; Khalil, Md. Ibrahim

2014-01-01

Diabetic wounds are unlike typical wounds in that they are slower to heal, making treatment with conventional topical medications an uphill process. Among several different alternative therapies, honey is an effective choice because it provides comparatively rapid wound healing. Although honey has been used as an alternative medicine for wound healing since ancient times, the application of honey to diabetic wounds has only recently been revived. Because honey has some unique natural features as a wound healer, it works even more effectively on diabetic wounds than on normal wounds. In addition, honey is known as an “all in one” remedy for diabetic wound healing because it can combat many microorganisms that are involved in the wound process and because it possesses antioxidant activity and controls inflammation. In this review, the potential role of honey's antibacterial activity on diabetic wound-related microorganisms and honey's clinical effectiveness in treating diabetic wounds based on the most recent studies is described. Additionally, ways in which honey can be used as a safer, faster, and effective healing agent for diabetic wounds in comparison with other synthetic medications in terms of microbial resistance and treatment costs are also described to support its traditional claims. PMID:25386217

10 x '20 Progress--development of new drugs active against gram-negative bacilli: an update from the Infectious Diseases Society of America.

PubMed

Boucher, Helen W; Talbot, George H; Benjamin, Daniel K; Bradley, John; Guidos, Robert J; Jones, Ronald N; Murray, Barbara E; Bonomo, Robert A; Gilbert, David

2013-06-01

Infections caused by antibiotic-resistant bacteria, especially the "ESKAPE" pathogens, continue to increase in frequency and cause significant morbidity and mortality. New antimicrobial agents are greatly needed to treat infections caused by gram-negative bacilli (GNB) resistant to currently available agents. The Infectious Diseases Society of America (IDSA) continues to propose legislative, regulatory, and funding solutions to this continuing crisis. The current report updates the status of development and approval of systemic antibiotics in the United States as of early 2013. Only 2 new antibiotics have been approved since IDSA's 2009 pipeline status report, and the number of new antibiotics annually approved for marketing in the United States continues to decline. We identified 7 drugs in clinical development for treatment of infections caused by resistant GNB. None of these agents was included in our 2009 list of antibacterial compounds in phase 2 or later development, but unfortunately none addresses the entire spectrum of clinically relevant GNB resistance. Our survey demonstrates some progress in development of new antibacterial drugs that target infections caused by resistant GNB, but progress remains alarmingly elusive. IDSA stresses our conviction that the antibiotic pipeline problem can be solved by the collaboration of global leaders to develop creative incentives that will stimulate new antibacterial research and development. Our aim is the creation of a sustainable global antibacterial drug research and development enterprise with the power in the short term to develop 10 new, safe, and efficacious systemically administered antibiotics by 2020 as called for in IDSA's "10 × '20 Initiative."

Benzimidazole-Based Antibacterial Agents Against F. tularensis

PubMed Central

Kumar, Kunal; Awasthi, Divya; Lee, Seung-Yub; Cummings, Jason E.; Knudson, Susan E.; Slayden, Richard A.; Ojima, Iwao

2013-01-01

Francisella tularensis is a highly virulent pathogenic bacterium. In order to identify novel potential antibacterial agents against F. tularensis, libraries of trisubstituted benzimidazoles were screened against F. tularensis LVS strain. In a preliminary screening assay, remarkably, 23 of 2,5,6- and 2,5,7-trisubstituted benzimidazoles showed excellent activity exhibiting greater than 90 % growth inhibition at 1 µg/mL. Among those hits, 21 compounds showed MIC90 values in the range of 0.35–48.6 µg/mL after accurate MIC determination. In ex-vivo efficacy assays, four of these compounds exhibited 2–3 Log reduction in colony forming units (CFU) per mL at concentrations of 10 and 50 µg/mL. PMID:23623254

Enantioselective Total Synthesis of Antibiotic CJ-16,264, Synthesis and Biological Evaluation of Designed Analogues, and Discovery of Highly Potent and Simpler Antibacterial Agents.

PubMed

Nicolaou, K C; Pulukuri, Kiran Kumar; Rigol, Stephan; Buchman, Marek; Shah, Akshay A; Cen, Nicholas; McCurry, Megan D; Beabout, Kathryn; Shamoo, Yousif

2017-11-08

An improved and enantioselective total synthesis of antibiotic CJ-16,264 through a practical kinetic resolution and an iodolactonization reaction to form the iodo pyrrolizidinone fragment of the molecule is described. A series of racemic and enantiopure analogues of CJ-16,264 was designed and synthesized through the developed synthetic technologies and tested against drug-resistant bacterial strains. These studies led to interesting structure-activity relationships and the identification of a number of simpler, and yet equipotent, or even more potent, antibacterial agents than the natural product, thereby setting the foundation for further investigations in the quest for new anti-infective drugs.

Antibacterial gold nanoparticles-biomass assisted synthesis and characterization.

PubMed

Badwaik, Vivek D; Willis, Chad B; Pender, Dillon S; Paripelly, Rammohan; Shah, Monic; Kherde, Yogesh A; Vangala, Lakshmisri M; Gonzalez, Matthew S; Dakshinamurthy, Rajalingam

2013-10-01

Xylose is a natural monosaccharide found in biomass such as straw, pecan shells, cottonseed hulls, and corncobs. Using this monosaccharide, we report the facile, green synthesis and characterization of stable xylose encapsulated gold nanoparticles (Xyl-GNPs) with potent antibacterial activity. Xyl-GNPs were synthesized using the reduction property of xylose in an aqueous solution containing choloraurate anions carried out at room temperature and atmospheric pressure. These nanoparticles were stable and near spherical in shape with an average diameter of 15 +/- 5 nm. Microbiological assay results showed the concentration dependent antibacterial activity of these particles against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) bacteria. Thus the facile, environmentally friendly Xyl-GNPs have many potential applications in chemical and biomedical industries, particularly in the development of antibacterial agents in the field of biomedicine.

Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms

PubMed Central

Zhang, Ke; Melo, Mary Anne S.; Cheng, Lei; Weir, Michael D.; Bai, Yuxing; Xu, Hockin H. K.

2012-01-01

Objectives Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time. Methods Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6). Results Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35 MPa (p > 0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p < 0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control. Significance Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a wide applicability to other dental bonding systems. PMID:22592165

Development of novel dental adhesive with double benefits of protein-repellent and antibacterial capabilities.

PubMed

Zhang, Ning; Weir, Michael D; Romberg, Elaine; Bai, Yuxing; Xu, Hockin H K

2015-07-01

Secondary caries at the tooth-restoration margins remains a main reason for restoration failure. The objectives of this study were to: (1) combine protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM) to develop a new dental adhesive with double benefits of protein-repellent and antibacterial capabilities for the first time; and (2) investigate the effects on protein adsorption, anti-biofilm activity, and dentin bond strength. MPC and DMAHDM were incorporated into Scotchbond Multi-Purpose (SBMP) primer and adhesive. Dentin shear bond strengths were measured using extracted human molars. Protein adsorption onto the adhesive resin surfaces was determined by the micro bicinchoninic acid (BCA) method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production and live/dead staining of biofilms on resins. Incorporation of 7.5% MPC and 5% DMAHDM into primer and adhesive did not adversely affect the dentin shear bond strength (p>0.1). The resin with 7.5% MPC+5% DMAHDM had protein adsorption that was nearly 20-fold less than SBMP control (p<0.05). The resin with 7.5% MPC+5% DMAHDM had much stronger antibacterial effects than using MPC or DMAHDM alone (p<0.05). Biofilm CFU counts on the resin with 7.5% MPC+5% DMAHDM were reduced by more than 4 orders of magnitude, compared to SBMP control. The use of double agents (protein-repellent MPC+antibacterial DMAHDM) in dental adhesive achieved much stronger inhibition of biofilms than using each agent alone. The novel protein-repellent and antibacterial bonding agent is promising to reduce biofilm/plaque buildup and reduce recurrent caries at the tooth-restoration margins. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Citrus fruit extracts with carvacrol and thymol eliminated 7-log acid-adapted Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes: A potential of effective natural antibacterial agents.

PubMed

Chung, Doohyun; Cho, Tae Jin; Rhee, Min Suk

2018-05-01

Despite the widespread belief that citrus fruit extracts (CFEs) are microbiologically safe due to their acidity, limited bactericidal effect results in low applicability as antibacterial agent and outbreaks occurred by acid-adapted pathogens. Here, we examined the antibacterial effects of CFEs [lime (Citrus medica), lemon (Citrus limon), calamansi (Citrus microcarpa)] combined with essential oil components (EOCs; carvacrol and thymol) against non-acid-adapted/acid-adapted Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes under 22 °C for 5 min. CFEs (<20%) alone or small amounts of EOCs (2.0 mM; 0.032%) alone could not inactivate the target bacteria effectively. However, combined treatments exhibited marked synergy: CFE + EOCs eliminated all the bacteria (>6.9 log CFU/ml). Among the CFEs tested, the highest synergism was shown by calamansi, an exotic citrus fruit previously unrecognized as an antibacterial agent. Although acid-adaptation improved bacterial survival, calamansi (<20%) + EOCs (<0.032%) completely inactivated even the most resistant pathogen (E. coli O157:H7). Validation test also showed that all tested commercial juice products also eliminated acid-adapted pathogens when used with EOCs. Physicochemical analysis of tested CFEs (pH measurement and HPLC analysis of components) revealed that low pH and flavanone (hesperidin) did not contribute to the synergistic bactericidal effects. Rather, the high citric acid content is likely to contribute to the strong synergistic effect with EOCs by damaging susceptible bacterial membranes. Sensory scores for CFEs were not altered by addition of EOCs at concentrations up to 1.5 mM. This study provides new insight into the utility of CFEs with EOCs to improve not only the microbiological safety of food products containing CFEs but also their applicability as natural antibacterial complex. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms.

PubMed

Zhang, Ke; Melo, Mary Anne S; Cheng, Lei; Weir, Michael D; Bai, Yuxing; Xu, Hockin H K

2012-08-01

Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time. Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6). Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35MPa (p>0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p<0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control. Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a wide applicability to other dental bonding systems. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Green-Tea and Epigallocatechin-3-Gallate are Bactericidal against Bacillus anthracis

DTIC Science & Technology

2017-06-13

EGCG, catechins such 245 as epigallocatechin and epicatechin gallate are also antibacterial agents. Moreover, the 246 bactericidal activity of green...Sharma A, Gupta S, Sarethy IP, Dang S, Gabrani R. 2012. Green tea extract: possible mechanism 285 and antibacterial activity on skin pathogens. Food...was shown to be responsible for this activity , against 30 both the attenuated B. anthracis ANR and the virulent, encapsulated strain B. anthracis

Antibacterial kaolinite/urea/chlorhexidine nanocomposites: Experiment and molecular modelling

NASA Astrophysics Data System (ADS)

Holešová, Sylva; Valášková, Marta; Hlaváč, Dominik; Madejová, Jana; Samlíková, Magda; Tokarský, Jonáš; Pazdziora, Erich

2014-06-01

Clay minerals are commonly used materials in pharmaceutical production both as inorganic carriers or active agents. The purpose of this study is the preparation and characterization of clay/antibacterial drug hybrids which can be further included in drug delivery systems for treatment oral infections. Novel nanocomposites with antibacterial properties were successfully prepared by ion exchange reaction from two types of kaolinite/urea intercalates and chlorhexidine diacetate. Intercalation compounds of kaolinite were prepared by reaction with solid urea in the absence of solvents (dry method) as well as with urea aqueous solution (wet method). The antibacterial activity of two prepared samples against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding the minimum inhibitory concentration (MIC). Antibacterial studies of both samples showed the lowest MIC values (0.01%, w/v) after 1 day against E. faecalis, E. coli and S. aureus. A slightly worse antibacterial activity was observed against P. aeruginosa (MIC 0.12%, w/v) after 1 day. Since samples showed very good antibacterial activity, especially after 1 day of action, this means that these samples can be used as long-acting antibacterial materials. Prepared samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental data are supported by results of molecular modelling.

Phenolic Compounds and In Vitro Antibacterial and Antioxidant Activities of Three Tropic Fruits: Persimmon, Guava, and Sweetsop

PubMed Central

Lu, WenQing; Zhou, XiaoMin

2016-01-01

In our previous study, we have found that persimmon, guava, and sweetsop owned considerably high antioxidant activity and contained high total phenolic contents as well. In order to further supply information on the antibacterial and antioxidant activity of these three tropic fruits, they were extracted by 80% methanol. We then examined the extractions about their phenolic compounds and also studied the extractions and phenolic contents about their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against twelve targeted pathogens including 8 standard strains (Staphylococcus aureus, Bacillus cereus, Staphylococcus epidermidis, Monilia albican, Escherichia coli, Salmonella typhimurium, Shigella flexneri, and Pseudomonas aeruginosa) and 4 multidrug-resistant strains (methicillin-resistant Staphylococcus aureus, ESBLs-producing Escherichia coli, carbapenems-resistant Pseudomonas aeruginosa, and multidrug-resistant Acinetobacter baumannii), which are common and comprehensive in clinic. We also employed two ways, that is, FRAP and TEAC, to evaluate their antioxidant activities, using ultraviolet and visible spectrophotometer. Our study indicated that the three tropical fruits possessed obvious antioxidant and antibacterial activity, which supported the possibility of developing the fruits into new natural resource food and functional food as well as new natural antimicrobial agent and food preservatives. Moreover, phenolic compounds detected in the fruits could be used as a potential natural antibacterial agent and antioxidant. PMID:27648444

Oxazolidinone antimicrobials: a patent review (2012-2015).

PubMed

Phillips, Oludotun A; Sharaf, Leyla H

2016-05-01

Antimicrobial resistance in Gram-positive bacteria is a major health care issue. This review summarizes patent publications from 2012 to 2015 that divulged novel oxazolidinones as antibacterial agents. A total of 25 patents obtained from Espacenet, WIPO Patentscope and FreePatentsOnline, and AcclaimIP search engines were reviewed. The patents were scrutinized based on the novelty of the compounds, their antibacterial activity (MIC, µg/mL), and the process of preparation. The oxazolidinones with promising antibacterial activity were classified according to the following structural diversities, as biaryl heterocyclic, fused heteroaryl rings containing oxazolidinones, and others. The biaryl heterocyclic, fused heteroaryl, benzoxazine, and the 1H-pyrazol-1-yl containing oxazolidinone derivatives demonstrated potent antibacterial activities superior to linezolid against Gram-positive bacteria. Some derivatives were effective against standard strains of Gram-negative bacteria, namely Moraxella catarrhalis ATCC A894, and Escherichia coli ATCC 25922. In addition, a patent disclosed a structural isomer of linezolid with marginal activity against the aerobic Gram-negative bacteria MDR Stenotrophomonas (Xanthomonas) maltophilia, while linezolid and vancomycin did not inhibit growth. Finally, some derivatives showed activity against respiratory infectious diseases' causative agents, such as B. anthracis, B. mallei, Y. pestis, and M. pneumoniae. Overall, there is limited in vivo data to support the potential clinical advancement of the currently reported novel derivatives.

Bacteriological profiling of diphenylureas as a novel class of antibiotics against methicillin-resistant Staphylococcus aureus

PubMed Central

Younis, Waleed; Ezzat, Hany G.; Peters, Christine E.; AbdelKhalek, Ahmed; Cooper, Bruce; Pogliano, Kit; Pogliano, Joe; Mayhoub, Abdelrahman S.; Seleem, Mohamed N.

2017-01-01

Bacterial resistance to antibiotics remains an imposing global public health challenge. Of the most serious pathogens, methicillin-resistant Staphylococcus aureus (MRSA) is problematic given strains have emerged that exhibit resistance to several antibiotic classes including β-lactams and agents of last resort such as vancomycin. New antibacterial agents composed of unique chemical scaffolds are needed to counter this public health challenge. The present study examines two synthetic diphenylurea compounds 1 and 2 that inhibit growth of clinically-relevant isolates of MRSA at concentrations as low as 4 µg/mL and are non-toxic to human colorectal cells at concentrations up to 128 μg/mL. Both compounds exhibit rapid bactericidal activity, completely eliminating a high inoculum of MRSA within four hours. MRSA mutants exhibiting resistance to 1 and 2 could not be isolated, indicating a low likelihood of rapid resistance emerging to these compounds. Bacterial cytological profiling revealed the diphenylureas exert their antibacterial activity by targeting bacterial cell wall synthesis. Both compounds demonstrate the ability to resensitize vancomycin-resistant Staphylococcus aureus to the effect of vancomycin. The present study lays the foundation for further investigation and development of diphenylurea compounds as a new class of antibacterial agents. PMID:28797064

Efficacy of silver diamine fluoride as an antibacterial as well as antiplaque agent compared to fluoride varnish and acidulated phosphate fluoride gel: an in vivo study.

PubMed

Shah, Shalin; Bhaskar, Vijay; Venkataraghavan, Karthik; Choudhary, Prashant; Ganesh, M; Trivedi, Krishna

2013-01-01

Silver diamine fluoride (SDF) is already proven as an antibacterial agent in vitro. Present study was formulated to compare the efficacy of SDF as an antibacterial as well as antiplaque agent in vivo with fluoride varnish and acidulated phosphate fluoride (APF) gel. Total 123 children (male = 82, female = 41) were included in the study for a period of 18 months. Children were divided into three different groups-Group 1: SDF; Group 2: fluoride varnish; and Group 3: APF gel. All subjects were evaluated via plaque score at 6 th, 12 th, and 18 th months as well as Streptococcus mutans counts in saliva at 72 h, 6 th, 12 th, and 18 th months of follow-up. Significant reduction was found in plaque score as well as S. mutans counts irrespective of group division. On intergroup comparison, no statistically significant difference was found in plaque score, but significant reduction in S. mutans counts was found in Group 1 as compared with Groups 2 and 3, while no significant difference was found between Groups 2 and 3. In vivo application of SDF on enamel significantly decreases S. mutans counts as compared to fluoride varnish and APF gel.

Ecology of Anti-Biofilm Agents I: Antibiotics versus Bacteriophages

PubMed Central

Abedon, Stephen T.

2015-01-01

Bacteriophages, the viruses that infect bacteria, have for decades been successfully used to combat antibiotic-resistant, chronic bacterial infections, many of which are likely biofilm associated. Antibiotics as anti-biofilm agents can, by contrast, be inefficacious against even genetically sensitive targets. Such deficiencies in usefulness may result from antibiotics, as naturally occurring compounds, not serving their producers, in nature, as stand-alone disruptors of mature biofilms. Anti-biofilm effectiveness by phages, by contrast, may result from a combination of inherent abilities to concentrate lytic antibacterial activity intracellularly via bacterial infection and extracellularly via localized population growth. Considered here is the anti-biofilm activity of microorganisms, with a case presented for why, ecologically, bacteriophages can be more efficacious than traditional antibiotics as medically or environmentally applied biofilm-disrupting agents. Four criteria, it can be argued, generally must be met, in combination, for microorganisms to eradicate biofilms: (1) Furnishing of sufficiently effective antibacterial factors, (2) intimate interaction with biofilm bacteria over extended periods, (3) associated ability to concentrate antibacterial factors in or around targets, and, ultimately, (4) a means of physically disrupting or displacing target bacteria. In nature, lytic predators of bacteria likely can meet these criteria whereas antibiotic production, in and of itself, largely may not. PMID:26371010

Preliminary investigations on the antibacterial activity of zinc oxide nanostructures

NASA Astrophysics Data System (ADS)

Ramani, Meghana; Ponnusamy, S.; Muthamizhchelvan, C.

2013-04-01

In this study, we present a systematic investigation on the evolution of nanorods of diameter 35-40 nm and 1-2 μm length from nanoparticles of diameter 30-35 nm by varying the concentration of 2,6-lutidine which acts as a shape-directing agent in the synthesis process. This variation in morphology was studied using transmission electron microscopy. The surface capping agent was subsequently removed by heating during the synthesis process and confirmed using Fourier Transform Infra-red spectroscopy. Sufficient quantity of surface defects in the form of oxygen vacancies was observed from the photoluminescence analysis of the synthesized nanostructures. The concentration of defects decreased as the shape transits from nanoparticles to nanorods. The synthesized samples were preliminarily studied for their antibacterial activity against four model (gram-positive and gram-negative) pathogens by disk diffusion method and growth curve analysis. The calculated generation time indicates higher activity for nanoparticles than nanorods. However, the difference in the activity against different pathogens and their dependence on the concentration of defects indicate oxidative stress in addition to mechanical membrane damage as the major toxicity mechanism. Overall, the experimental findings are preliminary evidence supporting the possibility of developing zinc oxide nanostructures as antibacterial agents against a wide range of microorganisms to control and prevent the spreading of bacterial infections.

Plasmin digest of κ-casein as a source of antibacterial peptides.

PubMed

Sedaghati, Marjaneh; Ezzatpanah, Hamid; Boojar, Masoud Mashhadi Akbar; Ebrahimi, Maryam Tajabadi; Aminafshar, Mehdi

2014-05-01

This study investigated the antibacterial properties of plasmin, the plasmin hydrolysis of bovine κ-casein and the fractions (named κC1, κC2, κC3, κC4, and κC5) liberated from it using RP-HPLC. The target bacteria were Escherichia coli, Staphylococcus aureus (pathogenic), Lactobacillus casei and Lactobacillus acidophilus (probiotic). Three peptides (kC1, kC3, and kC4) were found to have antibacterial activity, with κC3 peptide being the most active. The plasmin digest of bovine κ-casein proved to be stronger than any of its fractions in terms of antibacterial potential. Measurement of the minimum inhibitory concentration (MIC) showed that Gram-positive bacteria are generally more sensitive to antibacterial activity than Gram-negative bacteria. The MIC of nisin, as a bacteriocin peptide, was also measured. The three antibacterial peptides were identified using LC-Mass. The molecular mass of kC1, kC3, and kC4 corresponded to the f(17-21), f(22-24), and f(1-3) of bovine κ-casein, respectively. It was also found that the positive charge and hydrophobicity of a peptide are not key factors in antibacterial activity. On the whole, the present study demonstrated that the plasmin digest of κ-casein has a high antibacterial potential and can be considered as a natural antibacterial agent in the food chain.

Effect of plasma superficial treatments on antibacterial functionalization and coloration of cellulosic fabrics

NASA Astrophysics Data System (ADS)

Ibrahim, Nabil A.; Eid, Basma M.; Abdel-Aziz, Mohamed S.

2017-01-01

Remarkable improvement in antibacterial activity and durability of different cellulosic substrates namely cotton, linen, viscose and lyocell was achieved by pre-surface modification using N2-plasma to create new active and binding sites, -NH2 groups, onto the modified fabric surfaces followed by subsequent loading of biosynthesized silver nanoparticles (Ag NPs) alone and in combination with certain antibiotics using exhaustion method. The imparted antibacterial activity against both G+ve (S. aureus) and G-ve (E. coli) pathogens was governed by type of substrate, extent of modification and subsequent loading of antibacterial agent, synergistic effect, and antibacterial activity as well as type of harmful bacteria. A remarkable antibacterial activity still retained even after 15 washings. In addition, incorporation of Ag NPs into pigment printing paste and into acid dyeing bath for combined coloration and functionalization of O2-plasma and N2-plasma pre-modified substrates respectively were successfully achieved. Moreover, both SEM images and EDS spectra of selected substrates revealed the change in surface morphology as well as the presence of the loaded Ag element onto the post-treated substrates.

Preparation and antibacterial properties of O-carboxymethyl chitosan/lincomycin hydrogels.

PubMed

He, Guanghua; Chen, Xiang; Yin, Yihua; Cai, Weiquan; Ke, Wanwan; Kong, Yahui; Zheng, Hua

2016-01-01

In this study, O-carboxymethyl chitosan (O-CMCS) was synthesized from chitosan and monochloroacetic acid. Then O-CMCS hydrogel was prepared by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) in which the lincomycin was packaged. The Fourier transform infrared spectrum and scanning electron microscopy were adopted to characterize the structure and morphology of the product. The influences of dosage of EDC/NHS and concentration of O-CMCS on the swelling properties of the hydrogels were investigated. The hydrogels performed good swelling capacities and obvious pH-sensitive properties. The antibacterial activities of the hydrogels were tested against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Compared with pure O-CMCS hydrogels, the antibacterial activities of O-CMCS/lincomycin hydrogels were significantly improved with the increase in the concentration of lincomycin against E. coli and S. aureus. With the increase in dosage of crosslinking agent or concentration of O-CMCS, the antibacterial activities both decreased gradually against the two bacteria. O-CMCS/lincomycin hydrogel was expected to be used for antibacterial material in view of its significant antibacterial activities.

Antibacterial activity of vegetables and juices.

PubMed

Lee, Yee-Lean; Cesario, Thomas; Wang, Yang; Shanbrom, Edward; Thrupp, Lauri

2003-01-01

We evaluated the antibacterial activities of various fruit and vegetable extracts on common potential pathogens including antibiotic-resistant strains. Standardized bacterial inocula were added to serial dilutions of sterile vegetable and fruit extracts in broth, with final bacterial concentrations of 10(4-5) cells/mL. After overnight incubation at 35 degrees C, antibacterial activity was measured by minimum inhibitory and minimum bactericidal dilutions (for raw juices) or concentrations (for tea). Among the vegetable and fruit extracts tested, all green vegetables showed no antibacterial activity on Staphylococcus epidermidis and Klebsiella pneumoniae. All purple and red vegetable and fruit juices had antibacterial activities in dilutions ranging from 1:2 to 1:16. Garlic juice had significant activity, with bactericidal action in dilutions ranging up to 1:128 of the original juice. Tea also had significant activity, with bactericidal action in concentrations ranging up to 1.6 mg/mL, against a spectrum of pathogens including resistant strains such as methicillin- and ciprofloxacin-resistant staphylococci, vancomycin-resistant enterococci, and ciprofloxacin-resistant Pseudomonas aeruginosa. Tea and garlic have the potential for exploration of broader applications as antibacterial agents.

Pahangensin A and B, two new antibacterial diterpenes from the rhizomes of Alpinia pahangensis Ridley.

PubMed

Sivasothy, Yasodha; Ibrahim, Halijah; Paliany, Audra Shaleena; Alias, Siti Aisyah; Awang, Khalijah

2013-12-01

The rhizomes of Alpinia pahangensis Ridley yielded a new bis-labdanic diterpene for which the name pahangensin A (1) was proposed along with a new labdane diterpene, pahangensin B (2). Their structures were elucidated by spectroscopic methods including, 1D and 2D NMR techniques and LCMS-IT-TOF analysis. Pahangensin A (1) was found to be an antibacterial agent against Staphylococcus aureus, Bacillus cereus and Bacillus subtilis with MIC values less than 100 μg/mL, respectively. Pahangensin B (2) exhibited antibacterial activity (MIC <100 μg/mL) against B. cereus. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis of 1-phenyl-3-(4'-nitrophenyl)-5-(3',4'-dimethoxy-6'-nitrophenyl)-2-pyrazoline and its antibacterial activity

NASA Astrophysics Data System (ADS)

Fauzi'ah, Lina; Wahyuningsih, Tutik Dwi

2017-03-01

Synthesis of pyrazoline substituted with nitro groups as antibacterial agent has been carried out by cycloaddition reaction. The compound was synthesized from chalcone and phenylhyrazine by refluxing them in 2-butanol for 24 h. The product was purified and characterized using FTIR and 1H-NMR spectrometers. The result showed that pyrazoline has been succesfully synthesized in 33.06% yield. The compund has antibacterial activity againts Bacillus subtilis and Shigella flexneri. However, it has tendency of activity for Gram-negative bacteria. In conclusion, the nitro groups that substituted in aromatic ring were predicted as a part of pharmacophore.

Enhancement of bismuth antibacterial activity with lipophilic thiol chelators.

PubMed Central

Domenico, P; Salo, R J; Novick, S G; Schoch, P E; Van Horn, K; Cunha, B A

1997-01-01

The antibacterial properties of bismuth are greatly enhanced when bismuth is combined with certain lipophilic thiol compounds. Antibacterial activity was enhanced from 25- to 300-fold by the following seven different thiols, in order of decreasing synergy: 1,3-propanedithiol, dimercaprol (BAL), dithiothreitol, 3-mercapto-2-butanol, beta-mercaptoethanol, 1-monothioglycerol, and mercaptoethylamine. The dithiols produced the greatest synergy with bismuth at optimum bismuth-thiol molar ratios of from 3:1 to 1:1. The monothiols were generally not as synergistic and required molar ratios of from 1:1 to 1:4 for optimum antibacterial activity. The most-active mono- or dithiols were also the most soluble in butanol. The intensity of the yellow formed by bismuth-thiol complexes reflected the degree of chelation and correlated with antibacterial potency at high molar ratios. The bismuth-BAL compound (BisBAL) was active against most bacteria, as assessed by broth dilution, agar diffusion, and agar dilution analyses. Staphylococci (MIC, 5 to 7 microM Bi3+) and Helicobacter pylori (MIC, 2.2 microM) were among the most sensitive bacteria. Gram-negative bacteria were sensitive (MIC, < 17 microM). Enterococci were relatively resistant (MIC, 63 microM Bi3+). The MIC range for anaerobes was 15 to 100 microM Bi3+, except for Clostridium difficile (MIC, 7.5 microM). Bactericidal activity averaged 29% above the MIC. Bactericidal activity increased with increasing pH and/or increasing temperature. Bismuth-thiol solubility, stability, and antibacterial activity depended on pH and the bismuth-thiol molar ratio. BisBAL was stable but ineffective against Escherichia coli at pH 4. Activity and instability (reactivity) increased with increasing alkalinity. BisBAL was acid soluble at a molar ratio of greater than 3:2 and alkaline soluble at a molar ratio of less than 2:3. In conclusion, certain lipophilic thiol compounds enhanced bismuth antibacterial activity against a broad spectrum of bacteria. The activity, solubility, and stability of BisBAL were strongly dependent on the pH, temperature, and molar ratio. Chelation of bismuth with certain thiol agents enhanced the solubility and lipophilicity of this cationic heavy metal, thereby significantly enhancing its potency and versatility as an antibacterial agent. PMID:9257744

Susceptibility in vitro of canine methicillin-resistant and -susceptible staphylococcal isolates to fusidic acid, chlorhexidine and miconazole: opportunities for topical therapy of canine superficial pyoderma.

PubMed

Clark, S M; Loeffler, A; Bond, R

2015-07-01

Increasing multidrug resistance amongst canine pathogenic staphylococci has renewed interest in topical antibacterial therapy for skin infections in the context of responsible veterinary prescribing. We therefore determined the activity in vitro of three clinically relevant topical agents and synergism between two of them against Staphylococcus pseudintermedius and Staphylococcus aureus. The MICs of fusidic acid (n = 199), chlorhexidine (n = 198), miconazole (n = 198) and a 1:1 combination of miconazole/chlorhexidine (n = 198) were determined for canine isolates [50 MRSA and 49 methicillin-resistant S. pseudintermedius (MRSP), 50 MSSA and 50 methicillin-susceptible S. pseudintermedius (MSSP)] collected from the UK and Germany using an agar dilution method (CLSI VET01-A4). Fractional inhibitory concentration (FIC) indices were calculated to assess the interaction of miconazole with chlorhexidine. MICs of each drug/combination were significantly (P < 0.0005) higher for S. aureus when compared with S. pseudintermedius. Most strains (n = 172) had an MIC of fusidic acid of ≤0.03 mg/L (MIC ≥64 mg/L, n = 5 MRSA). All strains had MICs of chlorhexidine of 0.5-4 mg/L, except for one MRSA (MIC = 8 mg/L). All but four strains had MICs of miconazole of 1-4 mg/L (MIC = 16 mg/L, n = 3; MIC = 256 mg/L, n = 1). Miconazole/chlorhexidine (1:1 ratio) had a synergistic effect against 49/50 MRSA, 31/50 MSSA, 12/49 MRSP and 23/49 MSSP. Since the majority of these staphylococci, including methicillin-resistant isolates, had MICs that should be readily exceeded by topical skin application of these agents, their therapeutic efficacy for canine superficial pyoderma should be assessed. The synergistic interaction shown in vitro supports further clinical evaluation of miconazole/chlorhexidine combination therapy for staphylococcal infection. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.

Synthesis, evaluation and molecular docking studies of amino acid derived N-glycoconjugates as antibacterial agents.

PubMed

Baig, Noorullah; Singh, Rajnish Prakash; Chander, Subhash; Jha, Prabhat Nath; Murugesan, Sankaranarayanan; Sah, Ajay K

2015-12-01

Six amino acid derived N-glycoconjugates of d-glucose were synthesized, characterized and tested for antibacterial activity against G(+)ve (Bacillus cereus) as well as G(-)ve (Escherichia coli and Klebsiella pneumoniae) bacterial strains. All the tested compounds exhibited moderate to good antibacterial activity against these bacterial strains. The results were compared with the antibacterial activity of standard drug Chloramphenicol, where results of A5 (Tryptophan derived glycoconjugates) against E. coli and A4 (Isoleucine derived glycoconjugates) against K. pneumoniae bacterial strains are comparable with the standard drug molecule. In silico docking studies were also performed in order to understand the mode of action and binding interactions of these molecules. The docking studies revealed that, occupation of compound A5 at the ATP binding site of subunit GyrB (DNA gyrase, PDB ID: 3TTZ) via hydrophobic and hydrogen bonding interactions may be the reason for its significant in vitro antibacterial activity. Copyright © 2015 Elsevier Inc. All rights reserved.

Design, synthesis and antibacterial activity of cinnamaldehyde derivatives as inhibitors of the bacterial cell division protein FtsZ.

PubMed

Li, Xin; Sheng, Juzheng; Huang, Guihua; Ma, Ruixin; Yin, Fengxin; Song, Di; Zhao, Can; Ma, Shutao

2015-06-05

In an attempt to discover potential antibacterial agents against the increasing bacterial resistance, novel cinnamaldehyde derivatives as FtsZ inhibitors were designed, synthesized and evaluated for their antibacterial activity against nine significant pathogens using broth microdilution method, and their cell division inhibitory activity against four representative strains. In the in vitro antibacterial activity, the newly synthesized compounds generally displayed better efficacy against Staphylococcus aureus ATCC25923 than the others. In particular, compounds 3, 8 and 10 exerted superior or comparable activity to all the reference drugs. In the cell division inhibitory activity, all the compounds showed the same trend as their in vitro antibacterial activity, exhibiting better activity against S. aureus ATCC25923 than the other strains. Additionally, compounds 3, 6, 7 and 8 displayed potent cell division inhibitory activity with an MIC value of below 1 μg/mL, over 256-fold better than all the reference drugs. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

PubMed

Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

2014-03-01

A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. Copyright © 2013 Elsevier B.V. All rights reserved.

Novel 3-Aminothiazolquinolones: Design, Synthesis, Bioactive Evaluation, SARs, and Preliminary Antibacterial Mechanism.

PubMed

Cui, Sheng-Feng; Addla, Dinesh; Zhou, Cheng-He

2016-05-26

A series of novel 3-aminothiazolquinolones as analogues of quinolone antibacterial agents were designed and synthesized in an effort to circumvent quinolone resistance. Among these 3-aminothiazolquinolones, 3-(2-aminothiazol-4-yl)-7-chloro-6-(pyrrolidin-1-yl) quinolone 12b exhibited potent antibacterial activity, low cytotoxicity to hepatocyte cells, strong inhibitory potency to DNA gyrase, and a broad antimicrobial spectrum including against multidrug-resistant strains. This active molecule 12b also induced bacterial resistance more slowly than norfloxacin. Analysis of structure-activity relationships (SARs) disclosed that the 2-aminothiazole fragment at the 3-position of quinolone plays an important role in exerting antibacterial activity. Molecular modeling and experimental investigation of aminothiazolquinolone 12b with DNA from a sensitive methicillin-resistant Staphylococcus aureus (MRSA) strain revealed that the possible antibacterial mechanism might be related to the formation of a compound 12b-Cu(2+)-DNA ternary complex in which the Cu(2+) ion acts as a bridge between the backbone of 3-aminothiazolquinolone and the phosphate group of the nucleic acid.

Isolation, characterization and chromatography based purification of antibacterial compound isolated from rare endophytic actinomycetes Micrococcus yunnanensis.

PubMed

Ranjan, Ravi; Jadeja, Vasantba

2017-10-01

Endophytic actinomycetes are considered as one of the relatively unexplored potential sources in search of antibiotic producer against antibiotic resistant pathogens. A potent strain isolated from Catharanthus roseus that displays antibacterial potential against antibiotic resistant human pathogen Staphylococcus aureus was characterized and designated as Micrococcus yunnanensis strain rsk5. Rsk5 is capable of producing optimum antibacterial metabolites on starch casein medium at 30 °C, pH 5 and 2% NaCl condition. The crude antibacterial agent was extracted from fermentation broth by ethyl acetate and separated by TLC using chloroform-methanol (24:1, v/v) solvent system with R f value of 0.26. It was partially purified by flash chromatography, followed by HPLC and analyzed by ultraviolet visible spectrophotometer to get absorption maxima at 208.4 nm. The ESI-MS spectra showed molecular ion peaks at m / z 472.4 [M-H], which does not match with any known antibacterial compound.

Synthesis and Antibacterial Activities of Antibacterial Peptides with a Spiropyran Fluorescence Probe

PubMed Central

Chen, Lei; Zhu, Yu; Yang, Danling; Zou, Rongfeng; Wu, Junchen; Tian, He

2014-01-01

In this report, antibacterial peptides1-3 were prepared with a spiropyran fluorescence probe. The probe exhibits a change in fluorescence when isomerized from a colorless spiro-form (spiropyran, Sp) to a colored open-form (merocyanine, Mc) under different chemical environments, which can be used to study the mechanism of antimicrobial activity. Peptides 1-3 exhibit a marked decrease in antimicrobial activity with increasing alkyl chain length. This is likely due to the Sp-Mc isomers in different polar environments forming different aggregate sizes in TBS, as demonstrated by time-dependent dynamic light scattering (DLS). Moreover, peptides 1-3 exhibited low cytotoxicity and hemolytic activity. These probe-modified peptides may provide a novel approach to study the effect of structural changes on antibacterial activity, thus facilitating the design of new antimicrobial agents to combat bacterial infection. PMID:25358905

Synthesis of Some New Tetrahydropyrimidine Derivatives as Possible Antibacterial Agents.

PubMed

Foroughifar, Naser; Karimi Beromi, Somayeh; Pasdar, Hoda; Shahi, Masoumeh

2017-01-01

Heterocyclic compounds containing a pyrimidine nucleus are of special interests thanks to their applications in medicinal chemistry as they are the basic skeleton of several bioactive compounds such as antifungal, antibacterial, antitumor and antitubercular. As a part of our research in the synthesis of pyrimidine derivatives containing biological activities, some new tetrahydropyrimidine derivatives (1-10) were synthesized via Biginelli reaction using HCl or DABCO as a catalyst with good yields. All structures of products were confirmed by IR, 1 H NMR and 13 C NMR spectroscopy. The antibacterial activity of some synthesized compounds was investigated against Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228) , Bacillus cereus (ATCC14579) , Esherichia coli (ATCC 25922), Klebsiella pneumonia (ATCC 13883) and Pseudomonas aeruginosa (PAO1) bacteria. Some of these compounds such as 8 and 10 exhibited a good to significant antibacterial activity.

Synthesis of Some New Tetrahydropyrimidine Derivatives as Possible Antibacterial Agents

PubMed Central

Foroughifar, Naser; Karimi Beromi, Somayeh; Pasdar, Hoda; Shahi, Masoumeh

2017-01-01

Heterocyclic compounds containing a pyrimidine nucleus are of special interests thanks to their applications in medicinal chemistry as they are the basic skeleton of several bioactive compounds such as antifungal, antibacterial, antitumor and antitubercular. As a part of our research in the synthesis of pyrimidine derivatives containing biological activities, some new tetrahydropyrimidine derivatives (1-10) were synthesized via Biginelli reaction using HCl or DABCO as a catalyst with good yields. All structures of products were confirmed by IR, 1H NMR and 13C NMR spectroscopy. The antibacterial activity of some synthesized compounds was investigated against Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228), Bacillus cereus (ATCC14579), Esherichia coli (ATCC 25922), Klebsiella pneumonia (ATCC 13883) and Pseudomonas aeruginosa (PAO1) bacteria. Some of these compounds such as 8 and 10 exhibited a good to significant antibacterial activity. PMID:28979312

In silico modeling and synthesis of phenyl and thienyl analogs of chalcones for potential leads as anti-bacterial agents

NASA Astrophysics Data System (ADS)

Kar, Swayamsiddha; Mishra, Rohit Kumar; Pathak, Ashutosh; Dikshit, Anupam; Golakoti, Nageswara Rao

2018-03-01

In the recent times, the common diseases like food poisoning, pneumonia, diarrhea etc. have been observed to be drug resistant. The present study deals with the synthesis of known chalcone derivatives using the Claisen-Schmidt condensation and further characterization using UV-vis, IR, 1H NMR, 13C NMR and mass spectrometry. These derivatives were first simulated for their anti-bacterial efficacy in silico and consequently confirmed in vitro to confirm the findings. One of the chalcones, 4-NDM-2‧-HC showed excellent in-vitro antibacterial activity with an IC90 0.43 mg/mL against Vibrio cholerae as compared to commercially available antibiotic gentamicin as the standard. Further, all these tested chalcone derivatives fulfill Lipinski's parameters and show tremendous drug likeness score, confirming their potential as antibacterial leads.

Synthesis and Evaluation of Curcuminoid Analogues as Antioxidant and Antibacterial Agents.

PubMed

Emam, Dalia R; Alhajoj, Ahmad M; Elattar, Khaled M; Kheder, Nabila A; Fadda, Ahmed A

2017-06-11

Diazocoupling reaction of curcumin with different diazonium salts of p -toluidine, 2-aminopyridine, and 4-aminoantipyrine in pyridine yielded the arylhydrazones 2a - c . Arylhydrazone of p -toluidine reacted with urea, thiourea, and guanidine nitrate to produce 5,6-dihydropyrimidines. Further reaction of 2a with 2,3-diaminopyrdine in sodium ethoxide solution yielded 1 H -pyrido[2,3- b ][1,4]diazepine derivative. Bis (2,5-dihydroisoxazole) is obtained from the reaction of 2a with hydroxylamine hydrochloride, while its reactions with hydrazines afforded the respective 4,5-dihydro-1 H -pyrazoles. The target compounds were evaluated as antioxidant and antibacterial agents. The tested compounds showed good to moderate activities compared to ascorbic acid and chloramphenicol, respectively.

Comparison of the antibacterial activity of different self-etching primers and adhesives.

PubMed

Korkmaz, Yonca; Ozalp, Meral; Attar, Nuray

2008-11-01

The aim of this study was to evaluate the antibacterial effects of different one-step and two-step self-etching primer/adhesives on Streptococcus mutans (S. mutans), Lactobacillus casei (L. casei), and Lactobacillus acidophilus (L. acidophilus). The antibacterial effects of Clearfil Protect Bond Primer and Bonding agent; AdheSE Primer and Bonding agent; Adper Prompt L-Pop; Futurabond NR; Clearfil Tri S Bond; and Cervitec (positive control, 1% chlorhexidine varnish) were tested against standard strains of S. mutans, L. Casei, and L. acidophilus using the disk diffusion method. Standard filter paper disks (n=5) impregnated with 20 microL of each material were prepared. After incubation at 37 masculineC for 48 hours in a 5-10% CO2 atmosphere, the diameter of inhibition zones were measured in millimeters. Data were analyzed using one way analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA). Duncan's Multiple Range Test was used for pairwise comparison. The size of inhibition zones produced by primer/adhesives varied among the brands. AdheSE Primer: S. mutans (20.6+/-1.51); L. casei (14.8+/-1.78); L. acidophilus (11.4+/-0.54). Adper Prompt L-Pop: S. mutans (19.6+/-1.51); L. casei (13.8+/-1.64); L. acidophilus (13.8+/-1.09). Cervitec: S. mutans (23+/-0.00); L. casei (27+/-0.70); L. acidophilus (22.4+/-0.54). Clearfil Protect Bond Primer: S. mutans (17+/-0.00); L. casei (17.6+/-0.54); L. acidophilus (22.4+/-0.54). Futurabond NR was found effective only against S. mutans (14.6+/-1.67). Of all the materials tested, AdheSE Bonding agent, Clearfil Protect Bond Bonding agent, and Clearfil Tri S Bond exhibited no inhibition zone (-) for all bacteria tested. Among the adhesives tested Clearafil Protect Bond Primer based upon monomer methacryloyloxydodecylpyridiniium bromide (MDPB) was found to be the most potent material against L. acidophilus and L. casei. AdheSE Primer and Adper Prompt L-Pop are highly effective against S. mutans. Compared with other adhesive systems, Clearfil Protect Bond Primer (containing MDPB) showed a high antibacterial effect against all microorganizms tested. Two-step, self-etching primer/adhesive system Clearfil Protect Bond might be a suitable choice under minimally invasive restorations. The recently developed one-step, self-etching system Clearfil Tri S Bond showed no antibacterial effect against microorgazims tested.

10 × '20 Progress—Development of New Drugs Active Against Gram-Negative Bacilli: An Update From the Infectious Diseases Society of America

PubMed Central

Boucher, Helen W.; Talbot, George H.; Benjamin, Daniel K.; Bradley, John; Guidos, Robert J.; Jones, Ronald N.; Murray, Barbara E.; Bonomo, Robert A.; Gilbert, David

2013-01-01

Infections caused by antibiotic-resistant bacteria, especially the “ESKAPE” pathogens, continue to increase in frequency and cause significant morbidity and mortality. New antimicrobial agents are greatly needed to treat infections caused by gram-negative bacilli (GNB) resistant to currently available agents. The Infectious Diseases Society of America (IDSA) continues to propose legislative, regulatory, and funding solutions to this continuing crisis. The current report updates the status of development and approval of systemic antibiotics in the United States as of early 2013. Only 2 new antibiotics have been approved since IDSA's 2009 pipeline status report, and the number of new antibiotics annually approved for marketing in the United States continues to decline. We identified 7 drugs in clinical development for treatment of infections caused by resistant GNB. None of these agents was included in our 2009 list of antibacterial compounds in phase 2 or later development, but unfortunately none addresses the entire spectrum of clinically relevant GNB resistance. Our survey demonstrates some progress in development of new antibacterial drugs that target infections caused by resistant GNB, but progress remains alarmingly elusive. IDSA stresses our conviction that the antibiotic pipeline problem can be solved by the collaboration of global leaders to develop creative incentives that will stimulate new antibacterial research and development. Our aim is the creation of a sustainable global antibacterial drug research and development enterprise with the power in the short term to develop 10 new, safe, and efficacious systemically administered antibiotics by 2020 as called for in IDSA's “10 × '20 Initiative.” PMID:23599308

Furan-based benzene mono- and dicarboxylic acid derivatives as multiple inhibitors of the bacterial Mur ligases (MurC-MurF): experimental and computational characterization.

PubMed

Perdih, Andrej; Hrast, Martina; Pureber, Kaja; Barreteau, Hélène; Grdadolnik, Simona Golič; Kocjan, Darko; Gobec, Stanislav; Solmajer, Tom; Wolber, Gerhard

2015-06-01

Bacterial resistance to the available antibiotic agents underlines an urgent need for the discovery of novel antibacterial agents. Members of the bacterial Mur ligase family MurC-MurF involved in the intracellular stages of the bacterial peptidoglycan biosynthesis have recently emerged as a collection of attractive targets for novel antibacterial drug design. In this study, we have first extended the knowledge of the class of furan-based benzene-1,3-dicarboxylic acid derivatives by first showing a multiple MurC-MurF ligase inhibition for representatives of the extended series of this class. Steady-state kinetics studies on the MurD enzyme were performed for compound 1, suggesting a competitive inhibition with respect to ATP. To the best of our knowledge, compound 1 represents the first ATP-competitive MurD inhibitor reported to date with concurrent multiple inhibition of all four Mur ligases (MurC-MurF). Subsequent molecular dynamic (MD) simulations coupled with interaction energy calculations were performed for two alternative in silico models of compound 1 in the UMA/D-Glu- and ATP-binding sites of MurD, identifying binding in the ATP-binding site as energetically more favorable in comparison to the UMA/D-Glu-binding site, which was in agreement with steady-state kinetic data. In the final stage, based on the obtained MD data novel furan-based benzene monocarboxylic acid derivatives 8-11, exhibiting multiple Mur ligase (MurC-MurF) inhibition with predominantly superior ligase inhibition over the original series, were discovered and for compound 10 it was shown to possess promising antibacterial activity against S. aureus. These compounds represent novel leads that could by further optimization pave the way to novel antibacterial agents.

C8-Linked Pyrrolobenzodiazepine Monomers with Inverted Building Blocks Show Selective Activity against Multidrug Resistant Gram-Positive Bacteria.

PubMed

Andriollo, Paolo; Hind, Charlotte K; Picconi, Pietro; Nahar, Kazi S; Jamshidi, Shirin; Varsha, Amrit; Clifford, Melanie; Sutton, J Mark; Rahman, Khondaker Miraz

2018-02-09

Antimicrobial resistance has become a major global concern. Development of novel antimicrobial agents for the treatment of infections caused by multidrug resistant (MDR) pathogens is an urgent priority. Pyrrolobenzodiazepines (PBDs) are a promising class of antibacterial agents initially discovered and isolated from natural sources. Recently, C8-linked PBD biaryl conjugates have been shown to be active against some MDR Gram-positive strains. To explore the role of building block orientations on antibacterial activity and obtain structure activity relationship (SAR) information, four novel structures were synthesized in which the building blocks of previously reported compounds were inverted, and their antibacterial activity was studied. The compounds showed minimum inhibitory concentrations (MICs) in the range of 0.125-32 μg/mL against MDR Gram-positive strains with a bactericidal mode of action. The results showed that a single inversion of amide bonds reduces the activity while the double inversion restores the activity against MDR pathogens. All inverted compounds did not stabilize DNA and lacked eukaryotic toxicity. The compounds inhibit DNA gyrase in vitro, and the most potent compound was equally active against both wild-type and mutant DNA gyrase in a biochemical assay. The observed activity of the compounds against methicillin resistant S. aureus (MRSA) strains with equivalent gyrase mutations is consistent with gyrase inhibition being the mechanism of action in vivo, although this has not been definitively confirmed in whole cells. This conclusion is supported by a molecular modeling study showing interaction of the compounds with wild-type and mutant gyrases. This study provides important SAR information about this new class of antibacterial agents.

Furan-based benzene mono- and dicarboxylic acid derivatives as multiple inhibitors of the bacterial Mur ligases (MurC-MurF): experimental and computational characterization

NASA Astrophysics Data System (ADS)

Perdih, Andrej; Hrast, Martina; Pureber, Kaja; Barreteau, Hélène; Grdadolnik, Simona Golič; Kocjan, Darko; Gobec, Stanislav; Solmajer, Tom; Wolber, Gerhard

2015-06-01

Bacterial resistance to the available antibiotic agents underlines an urgent need for the discovery of novel antibacterial agents. Members of the bacterial Mur ligase family MurC-MurF involved in the intracellular stages of the bacterial peptidoglycan biosynthesis have recently emerged as a collection of attractive targets for novel antibacterial drug design. In this study, we have first extended the knowledge of the class of furan-based benzene-1,3-dicarboxylic acid derivatives by first showing a multiple MurC-MurF ligase inhibition for representatives of the extended series of this class. Steady-state kinetics studies on the MurD enzyme were performed for compound 1, suggesting a competitive inhibition with respect to ATP. To the best of our knowledge, compound 1 represents the first ATP-competitive MurD inhibitor reported to date with concurrent multiple inhibition of all four Mur ligases (MurC-MurF). Subsequent molecular dynamic (MD) simulations coupled with interaction energy calculations were performed for two alternative in silico models of compound 1 in the UMA/ d-Glu- and ATP-binding sites of MurD, identifying binding in the ATP-binding site as energetically more favorable in comparison to the UMA/ d-Glu-binding site, which was in agreement with steady-state kinetic data. In the final stage, based on the obtained MD data novel furan-based benzene monocarboxylic acid derivatives 8- 11, exhibiting multiple Mur ligase (MurC-MurF) inhibition with predominantly superior ligase inhibition over the original series, were discovered and for compound 10 it was shown to possess promising antibacterial activity against S. aureus. These compounds represent novel leads that could by further optimization pave the way to novel antibacterial agents.

Mechanism of MenE Inhibition by Acyl-Adenylate Analogues and Discovery of Novel Antibacterial Agents

PubMed Central

Sharma, Indrajeet; Lavaud, Lubens J.; Ngo, Stephen C.; Shek, Roger; Rajashankar, Kanagalaghatta R.; French, Jarrod B.; Tan, Derek S.; Tonge, Peter J.

2015-01-01

MenE is an o-succinylbenzoyl-CoA (OSB-CoA) synthetase in the bacterial menaquinone biosynthesis pathway and is a promising target for the development of novel antibacterial agents. The enzyme catalyzes CoA ligation via an acyl-adenylate intermediate, and we have previously reported tight-binding inhibitors of MenE based on stable acyl-sulfonyladenosine analogues of this intermediate, including OSB-AMS (1) which has an IC50 value of ≤ 25 nM for the Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in S. aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is ~1000-fold lower than the IC50 for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure–activity relationship (SAR) study stimulated by the knowledge that OSB-AMS can adopt two isomeric forms in which the OSB side chain exists either as an open-chain keto acid or a cyclic lactol. These studies revealed that negatively charged analogues of the keto-acid form bind, while neutral analogues do not, consistent with the hypothesis that the negatively-charged keto-acid form of OSB-AMS is the active isomer. X-ray crystallography and site-directed mutagenesis confirm the importance of a conserved arginine for binding the OSB carboxylate. Although most lactol isomers tested were inactive, a novel difluoroindanediol inhibitor (11) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future. PMID:26394156

Mechanism of MenE inhibition by acyl-adenylate analogues and discovery of novel antibacterial agents.

PubMed

Matarlo, Joe S; Evans, Christopher E; Sharma, Indrajeet; Lavaud, Lubens J; Ngo, Stephen C; Shek, Roger; Rajashankar, Kanagalaghatta R; French, Jarrod B; Tan, Derek S; Tonge, Peter J

2015-10-27

MenE is an o-succinylbenzoyl-CoA (OSB-CoA) synthetase in the bacterial menaquinone biosynthesis pathway and is a promising target for the development of novel antibacterial agents. The enzyme catalyzes CoA ligation via an acyl-adenylate intermediate, and we have previously reported tight-binding inhibitors of MenE based on stable acyl-sulfonyladenosine analogues of this intermediate, including OSB-AMS (1), which has an IC50 value of ≤25 nM for Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in Staphylococcus aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is ∼1000-fold lower than the IC50 for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure-activity relationship (SAR) study stimulated by the knowledge that OSB-AMS can adopt two isomeric forms in which the OSB side chain exists either as an open-chain keto acid or a cyclic lactol. These studies revealed that negatively charged analogues of the keto acid form bind, while neutral analogues do not, consistent with the hypothesis that the negatively charged keto acid form of OSB-AMS is the active isomer. X-ray crystallography and site-directed mutagenesis confirm the importance of a conserved arginine for binding the OSB carboxylate. Although most lactol isomers tested were inactive, a novel difluoroindanediol inhibitor (11) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future.

Antibacterial activity of crude extracts of some South African medicinal plants against multidrug resistant etiological agents of diarrhoea.

PubMed

Bisi-Johnson, Mary A; Obi, Chikwelu L; Samuel, Babatunde B; Eloff, Jacobus N; Okoh, Anthony I

2017-06-19

This study evaluated the antibacterial activity of some plants used in folklore medicine to treat diarrhoea in the Eastern Cape Province, South Africa. The acetone extracts of Acacia mearnsii De Wild., Aloe arborescens Mill., A. striata Haw., Cyathula uncinulata (Schrad.) Schinz, Eucomis autumnalis (Mill.) Chitt., E. comosa (Houtt.) Wehrh., Hermbstaedtia odorata (Burch. ex Moq.) T.Cooke, Hydnora africana Thunb, Hypoxis latifolia Wight, Pelargonium sidoides DC, Psidium guajava L and Schizocarphus nervosus (Burch.) van der Merwe were screened against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, multi-resistant Salmonella enterica serovar Isangi, S. typhi, S. enterica serovar Typhimurium, Shigella flexneri type 1b and Sh. sonnei phase II. A qualitative phytochemical screening of the plants extracts was by thin layer chromatography. Plants extracts were screened for antibacterial activity using serial dilution microplate technique and bioautography. The TLC fingerprint indicated the presence of terpenoids and flavonoids in the herbs. Most of the tested organisms were sensitive to the crude acetone extracts with minimum inhibitory concentration (MIC) values ranging from 0.018-2.5 mg/mℓ. Extracts of A. striata, C. uncinulata, E. autumnalis and P. guajava were more active against enteropathogens. S. aureus and Sh. flexneri were the most sensitive isolates to the crude extracts but of significance is the antibacterial activity of A. arborescens and P. guajava against a confirmed extended spectrum betalactamase positive S. enterica serovar Typhimurium. The presence of bioactive compounds and the antibacterial activity of some of the selected herbs against multidrug resistant enteric agents corroborate assertions by traditional healers on their efficacies.

In-vitro antibacterial study of zinc oxide nanostructures on Streptococcus sobrinus

NASA Astrophysics Data System (ADS)

Bakhori, Siti Khadijah Mohd; Mahmud, Shahrom; Ann, Ling Chuo; Sirelkhatim, Amna; Hasan, Habsah; Mohamad, Dasmawati; Masudi, Sam'an Malik; Seeni, Azman; Rahman, Rosliza Abd

2014-10-01

Zinc oxide nanostructures were prepared using a pilot plant of zinc oxide boiling furnace. Generally, it produced two types of nanostructures different in morphology; one is rod-like shaped (ZnO-1) and a plate-like shape (ZnO-2). The properties of ZnO were studied by structural, optical and morphological using XRD, PL and FESEM respectively. The XRD patterns confirmed the wurtzite structures of ZnO with the calculated crystallite size of 41 nm (ZnO-1) and 42 nm (ZnO-2) using Scherrer formula. The NBE peaks were determined by photoluminescence spectra which reveal peak at 3.25 eV and 3.23 eV for ZnO-1 and ZnO-2 respectively. Prior to that, the morphologies for both ZnO-1 and ZnO-2 were demonstrated from FESEM micrographs. Subsequently the antibacterial study was conducted using in-vitro broth dilution technique towards a gram positive bacterium Streptococcus sobrinus (ATCC 33478) to investigate the level of antibacterial effect of zinc oxide nanostructures as antibacterial agent. Gradual increment of ZnO concentrations from 10-20 mM affected the inhibition level after twenty four hours of incubation. In conjunction with concentration increment of ZnO, the percentage inhibition towards Streptococcus sobrinus was also increased accordingly. The highest inhibition occurred at 20 mM of ZnO-1 and ZnO-2 for 98% and 77% respectively. It showed that ZnO has good properties as antibacterial agent and relevancy with data presented by XRD, PL and FESEM were determined.

Carbon Nanoparticles decorated with cupric oxide Nanoparticles prepared by laser ablation in liquid as an antibacterial therapeutic agent

NASA Astrophysics Data System (ADS)

Khashan, Khawla S.; Jabir, Majid S.; Abdulameer, Farah A.

2018-03-01

Carbon nanoparticles (CNPs) decorated with cupric oxide nanoparticles (CuO NPs) were prepared by laser ablation in water, and their antibacterial activity was examined. X-ray diffraction measurements demonstrated the presence of carbon phases and different CuO phases, and results were confirmed by Fourier transform infrared analysis. Energy- Dispersive spectra showed the presence of C, O, and Cu in the final product. Transmission electron micrographs revealed that the CNPs were 10-80 nm in size and spherical; after being decorated with CuO NPs, particles became 5-50 nm in size and uniform in shape. The absorption spectrum of decorated Nanoparticles indicated the appearance of a new peak at 254-264 nm in addition to the fundamental peak at 228 nm. We then examined the antibacterial activity of the decorated CNPs for both gram-negative and -positive bacteria using the agar-well-diffusion method. The mode of action was determined using acridine orange-ethidium bromide staining to detect reactive oxygen species, and bacterial morphological change was studied by scanning electron microscopy. Results showed that CNPs decorated with 43% CuO NPs had the highest antibacterial activity for gram-positive bacteria. The CNPs acted on the cytoplasmic membrane and nucleic acid of bacteria, which led to a loss of cell-wall integrity, increased cell-wall permeability, and nucleic acid damage. The results offer a novel way to synthesis Carbon nanoparticles decorated with cupric oxide nanoparticles and could use them as novel antibacterial agent in future for pharmaceutical and biomedical applications.

Antibacterial and wound healing properties of chitosan/poly(vinyl alcohol)/zinc oxide beads (CS/PVA/ZnO).

PubMed

Gutha, Yuvaraja; Pathak, Janak L; Zhang, Weijiang; Zhang, Yaping; Jiao, Xu

2017-10-01

Treatment against bacterial infection is crucial for wound healing. Development of cost-effective antibacterial agent with wound healing properties is still in high demand. In this study we aimed to design chitosan/poly(vinyl alcohol)/zinc oxide (CS/PVA/ZnO) beads as novel antibacterial agent with wound healing properties. CS/PVA/ZnO beads were synthesized, and characterized by using XRD, FTIR, SEM, and TEM analysis. Pure chitosan exhibits two peaks at 2θ=10 and 20 and the CS/PVA polymer matrix exhibit the peaks at 2θ=19.7° and another of low intensity at 2θ=11.5°. Pure ZnO shows the characteristic peaks at (100), (002), (101), (102), (110), (103), (200), and (112) that were in good agreement with wurtzite ore having hexagonal lattice structure. The antibacterial activity of CS/PVA/ZnO against Escherichia coli, and Staphylococcus aureus were evaluated with the zone of inhibition method. Antibacterial activity of CS/PVA/ZnO was higher than that of chitosan (CS) and poly(vinyl alcohol (PVA). Hemocompatibility and biocompatibility of CS/PVA/ZnO were tested in in vitro. Wound healing properties of CS/PVA/ZnO were tested in mice skin wound. CS/PVA/ZnO showed strong antimicrobial, wound healing effect, hemocompatibility and biocompatibility. Hence the results strongly support the possibility of using this novel CS/PVA/ZnO material for the anti bacterial and wound healing application. Copyright © 2017 Elsevier B.V. All rights reserved.

Topical PDT in the Treatment of Benign Skin Diseases: Principles and New Applications.

PubMed

Kim, Miri; Jung, Haw Young; Park, Hyun Jeong

2015-09-25

Photodynamic therapy (PDT) uses a photosensitizer, light energy, and molecular oxygen to cause cell damage. Cells exposed to the photosensitizer are susceptible to destruction upon light absorption because excitation of the photosensitizing agents leads to the production of reactive oxygen species and, subsequently, direct cytotoxicity. Using the intrinsic cellular heme biosynthetic pathway, topical PDT selectively targets abnormal cells, while preserving normal surrounding tissues. This selective cytotoxic effect is the basis for the use of PDT in antitumor treatment. Clinically, PDT is a widely used therapeutic regimen for oncologic skin conditions such as actinic keratosis, squamous cell carcinoma in situ, and basal cell carcinoma. PDT has been shown, under certain circumstances, to stimulate the immune system and produce antibacterial, and/or regenerative effects while protecting cell viability. Thus, it may be useful for treating benign skin conditions. An increasing number of studies support the idea that PDT may be effective for treating acne vulgaris and several other inflammatory/infective skin diseases, including psoriasis, rosacea, viral warts, and aging-related changes. This review provides an overview of the clinical investigations of PDT and discusses each of the essential aspects of the sequence: its mechanism of action, common photosensitizers, light sources, and clinical applications in dermatology. Of the numerous clinical trials of PDT in dermatology, this review focuses on those studies that have reported remarkable therapeutic benefits following topical PDT for benign skin conditions such as acne vulgaris, viral warts, and photorejuvenation without causing severe side effects.

Assessment of antibacterial properties of newer dentin bonding agents: An in vitro study.

PubMed

Sampath, Pavitra B; Hegde, Mithra N; Hegde, Priyadarshini

2011-07-01

To evaluate and compare the antibacterial activity of newer dentin bonding agents on Streptococcus mutans using the direct contact test. Streptococcus mutans was used as test organism and a direct contact test was performed. The dentin bonding agents to be tested were grouped as Group I, Clearfil Protect Bond, Group II, Adper Easy One, and Group III, Prime and Bond NT. For the direct contact test, three microtiter plates consisting of 96 wells each were taken (288 wells). These wells were divided into three groups of 96 wells; 16 wells of a microtiter plate were utilized, of which four were designated as 'A' wells (with the dentin bonding agent and bacterial suspension), another four as 'B' wells (without the dentin bonding agent, but with the bacterial suspension), another four as the 'C' wells (with the tested material, but without bacteria, which served as the negative control), and the remaining four as the 'D' wells (without the dentin bonding agent, which served as the positive control). Each group was treated with their respective bonding agents as per the manufactures instructions. Broth of 15 μL was then transferred from the A wells into an adjacent set of B wells containing fresh medium (215 μL). This resulted in two sets of four wells for each tested material containing an equal volume of liquid medium, so that bacterial growth was monitored both in the presence and in the absence of the tested material. The plate was placed for incubation at 37°C in the microplate reader and the optical density in each well was measured at 600 nm. The readings were taken at regular intervals. (Every 30 minutes for 16 hours). The Dentin bonding agents evaluated in this study showed different inhibitory effects. Clearfil Protect Bond and Prime and Bond NT were most effective, and Adper Easy One was least effective against Streptococcus mutans. The Dentin bonding agents evaluated in this study showed different inhibitory effects. Clearfil Protect Bond and Prime and Bond NT were most effective, and Adper Easy One was the least effective against Streptococcus mutans. Hence, the incorporation of antibacterial agents into the dentin bonding agents may become an essential factor in inhibiting residual bacteria in the cavity and secondary caries.

Microgravity

NASA Image and Video Library

1989-02-03

(PCG) Protein Crystal Growth Gamma-Interferon. Stimulates the body's immune system and is used clinically in the treatment of cancer. Potential as an anti-tumor agent against solid tumors as well as leukemia's and lymphomas. It has additional utility as an anti-ineffective agent, including antiviral, anti-bacterial, and anti-parasitic activities. Principal Investigator on STS-26 was Charles Bugg.

Looking for the new preparations for antibacterial therapy III. New antimicrobial agents from the quinolones group in clinical trials.

PubMed

Karpiuk, Izabela; Tyski, Stefan

2013-01-01

There is an essential need for searching for the new compounds effective in the treatment of infections caused by multidrug-resistant bacteria. This paper is the third part of a series associated with the exploration of new antibacterial agents and it discusses the compounds belonging to the group of quinolones and substances possessing a hybrid structure composed of the quinolone molecule and other compounds. Eleven new substances at the stage of clinical trials are presented. Three of them belong to the group of non-fluorinated quinolone (nemonoxacin, ozenoxacin and KRP-AM 1977X), while six are the quinolones containing fluorine atom at 6 position of the carbon atom in the quinoline ring (zabofloxacin, finafloxacin, delafloxacin, JNJ-Q2, WCK771 and KPI-10). The remaining two compounds possess a hybrid construction composed of the quinolone structure and other molecules (cadazolid and CBR-2092). There is a chance in the near future, that the presented compounds can extend the range of existing antibacterial drugs and provide an alternative to currently available medicinal products.

Phenylthiazole Antibacterial Agents Targeting Cell Wall Synthesis Exhibit Potent Activity in Vitro and in Vivo against Vancomycin-Resistant Enterococci.

PubMed

Mohammad, Haroon; Younis, Waleed; Chen, Lu; Peters, Christine E; Pogliano, Joe; Pogliano, Kit; Cooper, Bruce; Zhang, Jianan; Mayhoub, Abdelrahman; Oldfield, Eric; Cushman, Mark; Seleem, Mohamed N

2017-03-23

The emergence of antibiotic-resistant bacterial species, such as vancomycin-resistant enterococci (VRE), necessitates the development of new antimicrobials. Here, we investigate the spectrum of antibacterial activity of three phenylthiazole-substituted aminoguanidines. These compounds possess potent activity against VRE, inhibiting growth of clinical isolates at concentrations as low as 0.5 μg/mL. The compounds exerted a rapid bactericidal effect, targeting cell wall synthesis. Transposon mutagenesis suggested three possible targets: YubA, YubB (undecaprenyl diphosphate phosphatase (UPPP)), and YubD. Both UPPP as well as undecaprenyl diphosphate synthase were inhibited by compound 1. YubA and YubD are annotated as transporters and may also be targets because 1 collapsed the proton motive force in membrane vesicles. Using Caenorhabditis elegans, we demonstrate that two compounds (1, 3, at 20 μg/mL) retain potent activity in vivo, significantly reducing the burden of VRE in infected worms. Taken altogether, the results indicate that compounds 1 and 3 warrant further investigation as novel antibacterial agents against drug-resistant enterococci.

Antimicrobial Activities of Three Medicinal Plants and Investigation of Flavonoids of Tripleurospermum disciforme.

PubMed

Tofighi, Zahra; Molazem, Maryam; Doostdar, Behnaz; Taban, Parisa; Shahverdi, Ahmad Reza; Samadi, Nasrin; Yassa, Narguess

2015-01-01

Rosa damascena, Tripleurospermum disciforme and Securigera securidaca were used as disinfectant agents and for treatment of some disease in folk medicine of Iran. The antimicrobial effects of different fractions of seeds extract of S. securidaca, petals extract of R. damascena and aerial parts extract of T. disciforme were examined against some gram positive, gram negative and fungi by cup plate diffusion method. The petroleum ether and chloroform fractions of S. securidaca showed antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa, while its methanol fraction had no antibacterial effects. R. damascena petals extract demonstrated antibacterial activities against Bacillus cereus, Staphylococcus epidermidis, S. aureus and Pseudomonas aeruginosa. T. disciforme aerial parts extract exhibited antimicrobial effects only against S. aureus and S. epidermidis. None of the fractions had any antifungal activities. Therefore, present study confirmed utility of these plants as disinfectant agents. Six flavonoids were isolated from T. disciforme: Luteolin, Quercetin-7-O-glucoside, Kaempferol, Kaempferol-7-O-glucoside, Apigenin and Apigenin-7-O-glucoside. The flavonoids and the antimicrobial activity of T. disciforme are reported for the first time.

Antimicrobial Activities of Three Medicinal Plants and Investigation of Flavonoids of Tripleurospermum disciforme

PubMed Central

Tofighi, Zahra; Molazem, Maryam; Doostdar, Behnaz; Taban, Parisa; Shahverdi, Ahmad Reza; Samadi, Nasrin; Yassa, Narguess

2015-01-01

Rosa damascena, Tripleurospermum disciforme and Securigera securidaca were used as disinfectant agents and for treatment of some disease in folk medicine of Iran. The antimicrobial effects of different fractions of seeds extract of S. securidaca, petals extract of R. damascena and aerial parts extract of T. disciforme were examined against some gram positive, gram negative and fungi by cup plate diffusion method. The petroleum ether and chloroform fractions of S. securidaca showed antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa, while its methanol fraction had no antibacterial effects. R. damascena petals extract demonstrated antibacterial activities against Bacillus cereus, Staphylococcus epidermidis, S. aureus and Pseudomonas aeruginosa. T. disciforme aerial parts extract exhibited antimicrobial effects only against S. aureus and S. epidermidis. None of the fractions had any antifungal activities. Therefore, present study confirmed utility of these plants as disinfectant agents. Six flavonoids were isolated from T. disciforme: Luteolin, Quercetin-7-O-glucoside, Kaempferol, Kaempferol-7-O-glucoside, Apigenin and Apigenin-7-O-glucoside. The flavonoids and the antimicrobial activity of T. disciforme are reported for the first time. PMID:25561928

Combinatorial Libraries As a Tool for the Discovery of Novel, Broad-Spectrum Antibacterial Agents Targeting the ESKAPE Pathogens.

PubMed

Fleeman, Renee; LaVoi, Travis M; Santos, Radleigh G; Morales, Angela; Nefzi, Adel; Welmaker, Gregory S; Medina-Franco, José L; Giulianotti, Marc A; Houghten, Richard A; Shaw, Lindsey N

2015-04-23

Mixture based synthetic combinatorial libraries offer a tremendous enhancement for the rate of drug discovery, allowing the activity of millions of compounds to be assessed through the testing of exponentially fewer samples. In this study, we used a scaffold-ranking library to screen 37 different libraries for antibacterial activity against the ESKAPE pathogens. Each library contained between 10000 and 750000 structural analogues for a total of >6 million compounds. From this, we identified a bis-cyclic guanidine library that displayed strong antibacterial activity. A positional scanning library for these compounds was developed and used to identify the most effective functional groups at each variant position. Individual compounds were synthesized that were broadly active against all ESKAPE organisms at concentrations <2 μM. In addition, these compounds were bactericidal, had antibiofilm effects, showed limited potential for the development of resistance, and displayed almost no toxicity when tested against human lung cells and erythrocytes. Using a murine model of peritonitis, we also demonstrate that these agents are highly efficacious in vivo.

Design and synthesis of some new pyrazolyl-pyrazolines as potential anti-inflammatory, analgesic and antibacterial agents.

PubMed

Viveka, Shivapura; Dinesha; Shama, Prasanna; Nagaraja, Gundibasappa Karikannar; Ballav, Shuvankar; Kerkar, Savita

2015-08-28

In the present study, an efficient synthesis of some new substituted pyrazoline derivatives linked to a substituted pyrazole scaffold was performed by a multistep reaction sequences and compounds were screened for their anti-inflammatory, analgesic and antibacterial activities. The preliminary results revealed that the N-acylated (5e, 5h) and nitro substituted N-phenyl (6f) pyrazolyl-pyrazolines derivatives exhibited a very promising anti-inflammatory activity whereas 5h, 6f were interesting analgesic agents. The compounds with halo substituted phenyl group at C-3 of the pyrazoline ring (4a, 5g, 5h, 6a and 6b) were found to be active against clinical bacterial pathogens with MIC in the range of 0.2-0.4 mg/mL. Compound containing N-propionyl pyrazolyl-pyrazoline (5h) could be identified as the most active member within this study with a dual anti-inflammatory and antibacterial profile. Taken together, this study has led to the development of promising compounds. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Dual-Targeting Small-Molecule Inhibitors of the Staphylococcus aureus FMN Riboswitch Disrupt Riboflavin Homeostasis in an Infectious Setting.

PubMed

Wang, Hao; Mann, Paul A; Xiao, Li; Gill, Charles; Galgoci, Andrew M; Howe, John A; Villafania, Artjohn; Barbieri, Christopher M; Malinverni, Juliana C; Sher, Xinwei; Mayhood, Todd; McCurry, Megan D; Murgolo, Nicholas; Flattery, Amy; Mack, Matthias; Roemer, Terry

2017-05-18

Riboswitches are bacterial-specific, broadly conserved, non-coding RNA structural elements that control gene expression of numerous metabolic pathways and transport functions essential for cell growth. As such, riboswitch inhibitors represent a new class of potential antibacterial agents. Recently, we identified ribocil-C, a highly selective inhibitor of the flavin mononucleotide (FMN) riboswitch that controls expression of de novo riboflavin (RF, vitamin B2) biosynthesis in Escherichia coli. Here, we provide a mechanistic characterization of the antibacterial effects of ribocil-C as well as of roseoflavin (RoF), an antimetabolite analog of RF, among medically significant Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis. We provide genetic, biophysical, computational, biochemical, and pharmacological evidence that ribocil-C and RoF specifically inhibit dual FMN riboswitches, separately controlling RF biosynthesis and uptake processes essential for MRSA growth and pathogenesis. Such a dual-targeting mechanism is specifically required to develop broad-spectrum Gram-positive antibacterial agents targeting RF metabolism. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lipopeptides as the Antifungal and Antibacterial Agents: Applications in Food Safety and Therapeutics

PubMed Central

Meena, Khem Raj; Kanwar, Shamsher S.

2015-01-01

A lot of crops are destroyed by the phytopathogens such as fungi, bacteria, and yeast leading to economic losses to the farmers. Members of the Bacillus genus are considered as the factories for the production of biologically active molecules that are potential inhibitors of growth of phytopathogens. Plant diseases constitute an emerging threat to global food security. Many of the currently available antimicrobial agents for agriculture are highly toxic and nonbiodegradable and thus cause extended environmental pollution. Moreover, an increasing number of phytopathogens have developed resistance to antimicrobial agents. The lipopeptides have been tried as potent versatile weapons to deal with a variety of phytopathogens. All the three families of Bacillus lipopeptides, namely, Surfactins, Iturins and Fengycins, have been explored for their antagonistic activities towards a wide range of phytopathogens including bacteria, fungi, and oomycetes. Iturin and Fengycin have antifungal activities, while Surfactin has broad range of potent antibacterial activities and this has also been used as larvicidal agent. Interestingly, lipopeptides being the molecules of biological origin are environmentally acceptable. PMID:25632392

Surveillance of Wisconsin Antibacterial Susceptibility Patterns.

PubMed

Munson, Erik; Block, Timothy K; Bowles, Erin J; Costello, Michael; Dern, Richard; Fritsche, Thomas R; Helgesen, Michael A; Kropp, Joshua L; Podzorski, Raymond P; Siebers, Karen; Simmons, Brian; Smith, Mary A; Spray, Frances; Van, Tam T; Warshauer, David M

2016-02-01

Antimicrobial resistance presents a threat to quality patient care. Knowledge of localantibacterial susceptibility patterns can guide clinicians in empiric antibacterial administration andassist pharmacists and infectious disease physicians in development of appropriate therapeutic pathways. To characterize Wisconsin antibacterial susceptibility patterns and elucidate geographicor temporal variation in antibacterial resistance, a retrospective, observational analysis of antibiogram data was performed. Seventy-two members of the Wisconsin Clinical Laboratory Network(WCLN) submitted antibiograms describing clinically significant isolates tested in calendar year 2013 to the WCLN Laboratory Technical Advisory Group. In the context of commonly reported antibacterial agents, data were compiled for approximately 75,800 isolates of Escherichia coi; 13,300 Klebsiella pneumoniae; 6300 Proteus mirobilis;2800 Enterobacter cloacae; 8400 Pseudomonas aeruginosa; 30,000 S aureus; 11,200 coagulase-negative Staphylococcus spp; and 13,800 Enterococcus spp. P mirobilis isolates from northern Wisconsin were more likely to demonstrate resistance than those in the southern region. In contrast, P aeruginosa isolates from southern Wisconsin had decreased susceptibility to a number ofagents when compared to other regions. Temporal trending in decreased E coli and P mirabilis susceptibility to fluoroquinolones and trimethoprimsulfamethoxazole was observed. Increased methicillin-resistant Staphylococcus oureus (MRSA) rates were observed in northwest and southeastWisconsin. In general, northeast Wisconsin exhibited less frequency of antibacterial resistance. Geographic variation exists with respect to antibacterial resistance, particularly inareas of Wisconsin adjacent to large population centers of neighboring states. Antibacterial surveillance in Wisconsin is indicated on a regular basis to assess emerging trends in antibacterial resistance. Existing WCLN infrastructure allows for such investigations.

[Dental plaque microcosm biofilm behavior on a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt].

PubMed

Junling, Wu; Qiang, Zhang; Ruinan, Sun; Ting, Zhu; Jianhua, Ge; Chuanjian, Zhou

2015-12-01

To develop a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt, and to measure its effect on human dental plaque microcosm biofilm. A novel nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt was synthesized according to methods introduced in previous research. Samples of the novel nano-antibacterial inorganic fillers were modified by a coupling agent and then added into resin composite at 0%, 5%, 10%, 15% or 20% mass fractions; 0% composite was used as control. A flexural test was used to measure resin composite mechanical properties. Results showed that a dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony-forming unit (CFU) counts, lactic acid production, and live/dead assay of biofilm on the resin composite were calculated to test the effect of the resin composite on human dental plaque microcosm biofilm. The incorporation of nano-antibacterial inorganic fillers with as much as 15% concentration into the resin composite showed no adverse effect on the mechanical properties of the resin composite (P > 0.05). Resin composite containing 5% or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilm, suggesting its strong antibacterial potency (P < 0.05). This novel resin composite exhibited a strong antibacterial property upon the addition of up to 5% nano-antibacterial inorganic fillers, thereby leading to effective caries inhibition in dental application.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata.

PubMed

Li, Chunlei; Zhu, Jianhua; Wang, Yanqing; Chen, Yuyan; Song, Liyan; Zheng, Weiming; Li, Jingjing; Yu, Rongmin

2017-06-29

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25-100 °C) and pH resistant (pH 3-10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria.

Microstructure, mechanical properties, bio-corrosion properties and antibacterial properties of Ti-Ag sintered alloys.

PubMed

Chen, Mian; Zhang, Erlin; Zhang, Lan

2016-05-01

In this research, Ag element was selected as an antibacterial agent to develop an antibacterial Ti-Ag alloy by a powder metallurgy. The microstructure, phase constitution, mechanical properties, corrosion resistance and antibacterial properties of the Ti-Ag sintered alloys have been systematically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), compressive test, electrochemical measurements and antibacterial test. The effects of the Ag powder size and the Ag content on the antibacterial property and mechanical property as well as the anticorrosion property have been investigated. The microstructure results have shown that Ti-Ag phase, residual pure Ag and Ti were the mainly phases in Ti-Ag(S75) sintered alloy while Ti2Ag was synthesized in Ti-Ag(S10) sintered alloy. The mechanical test indicated that Ti-Ag sintered alloy showed a much higher hardness and the compressive yield strength than cp-Ti but the mechanical properties were slightly reduced with the increase of Ag content. Electrochemical results showed that Ag powder size had a significant effect on the corrosion resistance of Ti-Ag sintered alloy. Ag content increased the corrosion resistance in a dose dependent way under a homogeneous microstructure. Antibacterial tests have demonstrated that antibacterial Ti-Ag alloy was successfully prepared. It was also shown that the Ag powder particle size and the Ag content influenced the antibacterial activity seriously. The reduction in the Ag powder size was benefit to the improvement in the antibacterial property and the Ag content has to be at least 3wt.% in order to obtain a strong and stable antibacterial activity against Staphylococcus aureus bacteria. The bacterial mechanism was thought to be related to the Ti2Ag and its distribution. Copyright © 2016 Elsevier B.V. All rights reserved.

Challenges of Antibacterial Discovery

PubMed Central

Silver, Lynn L.

2011-01-01

Summary: The discovery of novel small-molecule antibacterial drugs has been stalled for many years. The purpose of this review is to underscore and illustrate those scientific problems unique to the discovery and optimization of novel antibacterial agents that have adversely affected the output of the effort. The major challenges fall into two areas: (i) proper target selection, particularly the necessity of pursuing molecular targets that are not prone to rapid resistance development, and (ii) improvement of chemical libraries to overcome limitations of diversity, especially that which is necessary to overcome barriers to bacterial entry and proclivity to be effluxed, especially in Gram-negative organisms. Failure to address these problems has led to a great deal of misdirected effort. PMID:21233508

An assessment of the genetic toxicology of novel boron-containing therapeutic agents.

PubMed

Ciaravino, Vic; Plattner, Jacob; Chanda, Sanjay

2013-06-01

Boron-containing compounds are being studied as potential therapeutic agents. As part of the safety assessment of these therapeutic agents, a battery of genetic toxicology studies was conducted. The battery included a bacterial reverse mutation (Ames) assay, an in vitro chromosome aberration assay in peripheral human lymphocytes, and an in vivo rat micronucleus study. The following compounds represent some of the boron-containing compounds that have been advanced to human clinical trials in various therapeutic areas. The borinic picolinate, AN0128, is an antibacterial compound with anti-inflammatory activity that has been studied in clinical trials for acne and the treatment of mild to moderate atopic dermatitis. AN2690 (tavaborole) is a benzoxaborole in Phase 3 clinical trials for the topical treatment of onychomycosis, a fungal infection of the toenails and fingernails. Another benzoxaborole derivative, AN2728, a phosphodiesterase-4 (PDE4) inhibitor, is in Phase 2 clinical trials for the treatment of atopic dermatitis. AN2898, also a PDE4 inhibitor, has been studied in clinical trials for atopic dermatitis and psoriasis. AN3365 is a leucyl-tRNA synthetase inhibitor that has been in clinical development for the treatment of various Gram-negative bacterial infections. These five representative compounds were negative in the three genotoxicity assays. Furthermore, AN2690 has been studied in mouse and rat 2-year bioassays and was not found to have any carcinogenic potential. These results demonstrate that it is possible to design boron-based therapeutic agents with no genetic toxicology liabilities. Copyright © 2013 Wiley Periodicals, Inc.

Novel dental adhesives containing nanoparticles of silver and amorphous calcium phosphate

PubMed Central

Melo, Mary Anne S.; Cheng, Lei; Zhang, Ke; Weir, Michael D.; Rodrigues, Lidiany K. A.; Xu, Hockin H. K.

2012-01-01

Objectives Secondary caries is the main reason for restoration failure, and replacement of the failed restorations accounts for 50–70% of all restorations. Antibacterial adhesives could inhibit residual bacteria in tooth cavity and invading bacteria along the margins. Calcium (Ca) and phosphate (P) ion release could remineralize the lesions. The objectives of this study were to incorporate nanoparticles of silver (NAg) and nanoparticles of amorphous calcium phosphate (NACP) into adhesive for the first time, and to investigate the effects on dentin bond strength and plaque microcosm biofilms. Methods Scotchbond Multi-Purpose adhesive was used as control. NAg were added into primer and adhesive at 0.1% by mass. NACP were mixed into adhesive at 10%, 20%, 30% and 40%. Microcosm biofilms were grown on disks with primer covering the adhesive on a composite. Biofilm metabolic activity, colony-forming units (CFU) and lactic acid were measured. Results Human dentin shear bond strengths (n=10) ranged from 26 to 34 MPa; adding NAg and NACP into adhesive did not decrease the bond strength (p > 0.1). SEM examination revealed resin tags from well-filled dentinal tubules. Numerous NACP infiltrated into the dentinal tubules. While NACP had little antibacterial effect, NAg in bonding agents greatly reduced the biofilm viability and metabolic activity, compared to the control (p < 0.05). CFU for total microorganisms, total streptococci, and mutans streptococci on bonding agents with NAg were an order of magnitude less than those of the control. Lactic acid production by biofilms for groups containing NAg was 1/4 of that of the control. Significance Dental plaque microcosm biofilm viability and acid production were greatly reduced on bonding agents containing NAg and NACP, without compromising dentin bond strength. The novel method of incorporating dual agents (remineralizing agent NACP and antibacterial agent NAg) may have wide applicability to other dental bonding systems. PMID:23138046

Preparation of 8-hydroxyquinoline derivatives as potential antibiotics against Staphylococcus aureus.

PubMed

Lam, Kim-Hung; Gambari, Roberto; Lee, Kenneth Ka-Ho; Chen, Yi-Xin; Kok, Stanton Hon-Lung; Wong, Raymond Siu-Ming; Lau, Fung-Yi; Cheng, Chor-Hing; Wong, Wai-Yeung; Bian, Zhao-Xiang; Chan, Albert Sun-Chi; Tang, Johnny Cheuk-On; Chui, Chung-Hin

2014-01-01

This work describes the preparation of quinoline compounds as possible anti-bacterial agents. The synthesized quinoline derivatives show anti-bacterial activity towards Staphylococcus aureus. It is interesting to observe that the synthetic 5,7-dibromo-2-methylquinolin-8-ol (4) shows a similar minimum inhibitory concentration of 6.25μg/mL as compared to that of methicillin (3.125μg/mL) against Staphylococcus aureus. Copyright © 2013 Elsevier Ltd. All rights reserved.

U.S. Army Institute of Surgical Research Annual Research Progress Report for Fiscal Year 1989

DTIC Science & Technology

1989-10-01

inhibits dihydropteroate synthase. Antimicrob Agents Chemother (in press). 3. Klotz IM and Morrison RT: The antibacterial activity of p-amino...mit sulfonamidwirkung. Chem Ber 75:711-9, 1942. 5. Misiek M, Buck RE, Pursiano TA, et al: Antibacterial activity of phosphanilic acid, alone and in...10, associated inhalation injury, survived. Seven were returned to active duty. Less than three months later, early on the morning of 4 June 1989, at a

Antibacterial activity of tannins isolated from Sapium baccatum extract and use for control of tomato bacterial wilt.

PubMed

Vu, Thuy Thu; Kim, Hun; Tran, Vu Khac; Vu, Hoang Dinh; Hoang, Tien Xuan; Han, Jae Woo; Choi, Yong Ho; Jang, Kyoung Soo; Choi, Gyung Ja; Kim, Jin-Cheol

2017-01-01

In the search for new antibacterial agents from natural sources, we revealed that a crude methanol extract of Sapium baccatum was highly active against Ralstonia solanacearum, a causal agent of a serious disease called bacterial wilt of tomato. The bioassay-guided fractionation of this extract resulted in the isolation of seven known active compounds, including gallic acid, methyl gallate, corilagin, tercatain, chebulagic acid, chebulinic acid, and quercetin 3-O-α-L-arabinopyranoside. Their chemical structures were determined by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. An in vitro antibacterial bioassay using a broth microdilution method revealed that, except for quercetin 3-O-α-L-arabinopyranoside (MIC = 250 μg/mL), the isolated compounds exhibited strong antibacterial activity against R. solanacearum (MIC = 26-52 μg/mL). Among the seven compounds, methyl gallate exhibited the strongest broad-spectrum activity against most of the plant pathogenic bacteria tested (MIC = 26-250 μg/mL). In the in vivo experiments, the crude extract of S. baccatum at 2000 and 1000 μg/mL reduced the development of tomato bacterial wilt by 83 and 63%, respectively, under greenhouse conditions after 14 days of infection. The results suggested that the extracts of S. baccatum or isolated tannins could be used as natural bactericides for the control of bacterial wilt of tomato.

Antibacterial activity of tannins isolated from Sapium baccatum extract and use for control of tomato bacterial wilt

PubMed Central

Vu, Thuy Thu; Kim, Hun; Tran, Vu Khac; Vu, Hoang Dinh; Hoang, Tien Xuan; Han, Jae Woo; Choi, Yong Ho; Jang, Kyoung Soo; Choi, Gyung Ja

2017-01-01

In the search for new antibacterial agents from natural sources, we revealed that a crude methanol extract of Sapium baccatum was highly active against Ralstonia solanacearum, a causal agent of a serious disease called bacterial wilt of tomato. The bioassay-guided fractionation of this extract resulted in the isolation of seven known active compounds, including gallic acid, methyl gallate, corilagin, tercatain, chebulagic acid, chebulinic acid, and quercetin 3-O-α-L-arabinopyranoside. Their chemical structures were determined by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. An in vitro antibacterial bioassay using a broth microdilution method revealed that, except for quercetin 3-O-α-L-arabinopyranoside (MIC = 250 μg/mL), the isolated compounds exhibited strong antibacterial activity against R. solanacearum (MIC = 26–52 μg/mL). Among the seven compounds, methyl gallate exhibited the strongest broad-spectrum activity against most of the plant pathogenic bacteria tested (MIC = 26–250 μg/mL). In the in vivo experiments, the crude extract of S. baccatum at 2000 and 1000 μg/mL reduced the development of tomato bacterial wilt by 83 and 63%, respectively, under greenhouse conditions after 14 days of infection. The results suggested that the extracts of S. baccatum or isolated tannins could be used as natural bactericides for the control of bacterial wilt of tomato. PMID:28742863

Chemical agents for the control of plaque and plaque microflora: an overview.

PubMed

Gaffar, A; Afflitto, J; Nabi, N

1997-10-01

This presentation provides an overview of the technologies available for the chemical control of plaque. It is generally accepted that the formation of dental plaque at the interfaces of tooth/gingiva is one of the major causes of gingival inflammation and dental caries. Several therapeutic approaches have been used to control dental plaque and supragingival infections. These include fluoride preparations such as stannous fluoride, oxygenating agents, anti-attachment agents, and cationic and non-cationic antibacterial agents. Among the fluoride preparations, stable stannous fluoride pastes and gels have been shown to reduce supragingival plaque, gingivitis, hypersensitivity and caries. The effect of the oxygenating agents on the supragingival plaque has been equivocal, but recent data indicate that a stable agent which provides sustained active oxygen release is effective in controlling plaque. A polymer, PVPA, which reduced attachment of bacteria to teeth was shown to significantly reduce plaque formation in humans. A new generation of antibacterials includes non-ionics such as triclosan, which in combination with a special polymer delivery system, has been shown to reduce plaque, gingivitis, supragingival calculus and dental caries in long-term studies conducted around the world. Unlike the first generation of agents, the triclosan/copolymer/sodium fluoride system is effective in long-term clinicals and does not cause staining of teeth, increase in calculus, or disturbance in the oral microbial ecology.

Oral Candida in Patients with Fixed Orthodontic Appliance: In Vitro Combination Therapy.

PubMed

Alhamadi, Wisam; Al-Saigh, Rafal J; Al-Dabagh, Nebras N; Al-Humadi, Hussam W

2017-01-01

Fixed orthodontic appliance (FOA) increases the cariogenic microorganisms of mouth including candida. The aim was to evaluate the pharmacodynamic effects of some antibacterial drugs in combination with most applicable antifungal agents on candida isolated from patients with FOA. Three antifungal agents (amphotericin B (AMB), ketoconazole (KET), and itraconazole (ITZ)) and three antibacterial drugs (ciprofloxacin (CIP), doxycycline (DOX), and metronidazole (MET)) with serial concentrations have been used and microdilution broth method has been done for single and combination therapy, then fungal growth was assessed spectrophotometrically, and the combinations were evaluated by bliss independent analysis. According to bliss independent interaction, the synergistic interactions depended on Δ E values that showed the best for CIP was with AMB (Δ E = 55.14) followed with KET (Δ E = 41.23) and lastly ITR (Δ E = 39.67) at CIP = 150 mg/L. DOX was optimal with KET (Δ E = 42.11) followed with AMB (Δ E = 40.77) and the lowest with ITR (Δ E = 9.12) at DOX = 75 mg/L. MET is the best with AMB (Δ E = 40.95) and then with ITR (Δ E = 35.45) and finally KET (Δ E = 15.15) at MET 200 mg/L. Moreover, usage of higher concentrations of antibacterial agents revealed inhibitory effects. This study uncovers the optimum antibiotic combination therapy against cariogenic candida with FOA by usage of low therapeutic concentrations.

Effect of berberine on Escherichia coli, Bacillus subtilis, and their mixtures as determined by isothermal microcalorimetry.

PubMed

Kong, Wei-Jun; Xing, Xiao-Yan; Xiao, Xiao-He; Zhao, Yan-Ling; Wei, Jian-He; Wang, Jia-Bo; Yang, Rui-Chuang; Yang, Mei-Hua

2012-10-01

The strong toxicity of pathogenic bacteria has resulted in high levels of morbidity and mortality in the general population. Developing effective antibacterial agents with high efficacy and long activity is in great demand. In this study, the microcalorimetric technique based on heat output of bacterial metabolism was applied to evaluate the effect of berberine on Escherichia coli, Bacillus subtilis, individually and in a mixture of both using a multi-channel microcalorimeter. The differences in shape of the power-time fingerprints and thermokinetic parameters of microorganism growth were compared. The results revealed that low concentration (20 μg/mL) of berberine began to inhibit the growth of E. coli and mixed microorganisms, while promoting the growth of B. subtilis; high concentration of berberine (over 100 μg/mL) inhibited B. subtilis. The endurance of E. coli to berberine was obviously lower than B. subtilis, and E. coli could decrease the endurance of B. subtilis to berberine. The sequence of half-inhibitory concentration (IC(50)) of berberine was: B. subtilis (952.37 μg/mL) > mixed microorganisms (682.47 μg/mL) > E. coli (581.69 μg/mL). Berberine might be a good selection of antibacterial agent used in the future. The microcalorimetric method should be strongly suggested in screening novel antibacterial agents for fighting against pathogenic bacteria.

Volatile organic compounds produced by a soil-isolate, Bacillus subtilis FA26 induce adverse ultra-structural changes to the cells of Clavibacter michiganensis ssp. sepedonicus, the causal agent of bacterial ring rot of potato.

PubMed

Rajer, Faheem Uddin; Wu, Huijun; Xie, Yongli; Xie, Shanshan; Raza, Waseem; Tahir, Hafiz Abdul Samad; Gao, Xuewen

2017-04-01

Rhizobacterial volatile organic compounds (VOCs) play an important role in the suppression of soil-borne phytopathogens. In this study, the VOCs produced by a soil-isolate, Bacillus subtilis FA26, were evaluated in vitro for their antibacterial activity against Clavibacter michiganensis ssp. sepedonicus (Cms), the causal agent of bacterial ring rot of potato. The VOCs emitted by FA26 inhibited the growth of Cms significantly compared with the control. Scanning and transmission electron microscopy analyses revealed distorted colony morphology and a wide range of abnormalities in Cms cells exposed to the VOCs of FA26. Varying the inoculation strategy and inoculum size showed that the production and activity of the antibacterial VOCs of FA26 were dependent on the culture conditions. Headspace solid-phase microextraction/gas chromatography-mass spectrometry analyses revealed that FA26 produced 11 VOCs. Four VOCs (benzaldehyde, nonanal, benzothiazole and acetophenone) were associated with the antibacterial activity against Cms. The results suggested that the VOCs produced by FA26 could control the causal agent of bacterial ring rot of potato. This information will increase our understanding of the microbial interactions mediated by VOCs in nature and aid the development of safer strategies for controlling plant disease.

3D-QSAR and docking studies of flavonoids as potent Escherichia coli inhibitors

PubMed Central

Fang, Yajing; Lu, Yulin; Zang, Xixi; Wu, Ting; Qi, XiaoJuan; Pan, Siyi; Xu, Xiaoyun

2016-01-01

Flavonoids are potential antibacterial agents. However, key substituents and mechanism for their antibacterial activity have not been fully investigated. The quantitative structure-activity relationship (QSAR) and molecular docking of flavonoids relating to potent anti-Escherichia coli agents were investigated. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were developed by using the pIC50 values of flavonoids. The cross-validated coefficient (q2) values for CoMFA (0.743) and for CoMSIA (0.708) were achieved, illustrating high predictive capabilities. Selected descriptors for the CoMFA model were ClogP (logarithm of the octanol/water partition coefficient), steric and electrostatic fields, while, ClogP, electrostatic and hydrogen bond donor fields were used for the CoMSIA model. Molecular docking results confirmed that half of the tested flavonoids inhibited DNA gyrase B (GyrB) by interacting with adenosine-triphosphate (ATP) pocket in a same orientation. Polymethoxyl flavones, flavonoid glycosides, isoflavonoids changed their orientation, resulting in a decrease of inhibitory activity. Moreover, docking results showed that 3-hydroxyl, 5-hydroxyl, 7-hydroxyl and 4-carbonyl groups were found to be crucial active substituents of flavonoids by interacting with key residues of GyrB, which were in agreement with the QSAR study results. These results provide valuable information for structure requirements of flavonoids as antibacterial agents. PMID:27049530

Zinc

MedlinePlus

... Using toothpastes containing zinc, with or without an antibacterial agent, appears to prevent plaque and gingivitis. Some ... is some evidence that zinc has some antiviral activity against the herpes virus. Low zinc levels can ...

Antibacterial activity of sphagnum acid and other phenolic compounds found in Sphagnum papillosum against food-borne bacteria.

PubMed

Mellegård, H; Stalheim, T; Hormazabal, V; Granum, P E; Hardy, S P

2009-07-01

To identify the phenolic compounds in the leaves of Sphagnum papillosum and examine their antibacterial activity at pH appropriate for the undissociated forms. Bacterial counts of overnight cultures showed that whilst growth of Staphylococcus aureus 50084 was impaired in the presence of milled leaves, the phenol-free fraction of holocellulose of S. papillosum had no bacteriostatic effect. Liquid chromatography-mass spectrometry analysis of an acetone-methanol extract of the leaves detected eight phenolic compounds. Antibacterial activity of the four dominating phenols specific to Sphagnum leaves, when assessed in vitro as minimal inhibitory concentrations (MICs), were generally >2.5 mg ml(-1). MIC values of the Sphagnum-specific compound 'sphagnum acid' [p-hydroxy-beta-(carboxymethyl)-cinnamic acid] were >5 mg ml(-1). No synergistic or antagonistic effects of the four dominating phenols were detected in plate assays. Sphagnum-derived phenolics exhibit antibacterial activity in vitro only at concentrations far in excess of those found in the leaves. We have both identified the phenolic compounds in S. papillosum and assessed their antibacterial activity. Our data indicate that phenolic compounds in isolation are not potent antibacterial agents and we question their potency against food-borne pathogens.

New Potent Membrane-Targeting Antibacterial Peptides from Viral Capsid Proteins

PubMed Central

Dias, Susana A.; Freire, João M.; Pérez-Peinado, Clara; Domingues, Marco M.; Gaspar, Diana; Vale, Nuno; Gomes, Paula; Andreu, David; Henriques, Sónia T.; Castanho, Miguel A. R. B.; Veiga, Ana S.

2017-01-01

The increasing prevalence of multidrug-resistant bacteria urges the development of new antibacterial agents. With a broad spectrum activity, antimicrobial peptides have been considered potential antibacterial drug leads. Using bioinformatic tools we have previously shown that viral structural proteins are a rich source for new bioactive peptide sequences, namely antimicrobial and cell-penetrating peptides. Here, we test the efficacy and mechanism of action of the most promising peptides among those previously identified against both Gram-positive and Gram-negative bacteria. Two cell-penetrating peptides, vCPP 0769 and vCPP 2319, have high antibacterial activity against Staphylococcus aureus, MRSA, Escherichia coli, and Pseudomonas aeruginosa, being thus multifunctional. The antibacterial mechanism of action of the two most active viral protein-derived peptides, vAMP 059 and vCPP 2319, was studied in detail. Both peptides act on both Gram-positive S. aureus and Gram-negative P. aeruginosa, with bacterial cell death occurring within minutes. Also, these peptides cause bacterial membrane permeabilization and damage of the bacterial envelope of P. aeruginosa cells. Overall, the results show that structural viral proteins are an abundant source for membrane-active peptides sequences with strong antibacterial properties. PMID:28522994

Synthesis and structure-activity relationship studies of novel [6,6,5] tricyclic oxazolidinone derivatives as potential antibacterial agents.

PubMed

Xue, Tao; Ding, Shi; Guo, Bin; Chu, Wenjing; Wang, Hui; Yang, Yushe

2015-01-01

In our previous Letter, we reported the discovery of a novel benzoxazinyl-oxazolidinone antibacterial candidate 2. In order to identify a potential backup compound, extensive modifications on the B/C ring and C3 side chain were undertaken. A series of novel [6,6,5] tricyclic analogues were synthesized and their in vitro antibacterial activities were tested against a panel of susceptible and resistant Gram-positive pathogens. Among of them, benzothiazinyl-oxazolidinones with acetamide or thioamide as C3 side chains exhibited moderate to good antibacterial activity, such as compounds 54, 58, 59 and 63. In vitro liver microsomal stability was further evaluated and the results manifested that compounds 54 and 58 were both metabolically stable in rat and human liver microsomes. Additionally, insights gained from this investigation should provide directions for the further research of new oxazolidinone antibiotics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Phytochemical screening and in-vitro evaluation of pharmacological activities of peels of Musa sapientum and Carica papaya fruit.

PubMed

Siddique, Sarmad; Nawaz, Shamsa; Muhammad, Faqir; Akhtar, Bushra; Aslam, Bilal

2018-06-01

Aqueous, absolute and 80% ethanolic extract of fruit peels of Musa sapientum and Carica papaya were investigated for their antibacterial activity, measured by disc diffusion method and antioxidant activity, measured by four different methods. Papaya and banana peels were found to contain terpenoids, tannins, alkaloids, saponins steroid, phenols, fixed oils and fats. 80% ethanolic extract of banana peel was found to contain highest total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity but in papaya peel, highest TPC and reducing activity was shown by water extract while, TFC and radical scavenging activity was given by 80% ethanolic extract. In banana, water extract showed highest antibacterial activity against tested bacteria while in case of papaya, absolute ethanolic extract showed highest antibacterial activity. The present study revealed that peels of banana and papaya fruits are potentially good source of antioxidant and antibacterial agents.

Antibacterial Potential of Northeastern Portugal Wild Plant Extracts and Respective Phenolic Compounds

PubMed Central

Ferreira, Isabel C. F. R.; Barros, Lillian; Carvalho, Ana Maria; Soares, Graça; Henriques, Mariana

2014-01-01

The present work aims to assess the antibacterial potential of phenolic extracts, recovered from plants obtained on the North East of Portugal, and of their phenolic compounds (ellagic, caffeic, and gallic acids, quercetin, kaempferol, and rutin), against bacteria commonly found on skin infections. The disk diffusion and the susceptibility assays were used to identify the most active extracts and phenolic compounds. The effect of selected phenolic compounds on animal cells was assessed by determination of cellular metabolic activity. Gallic acid had a higher activity, against gram-positive (S. epidermidis and S. aureus) and gram-negative bacteria (K. pneumoniae) at lower concentrations, than the other compounds. The caffeic acid, also, showed good antibacterial activity against the 3 bacteria used. The gallic acid was effective against the 3 bacteria without causing harm to the animal cells. Gallic and caffeic acid showed a promising applicability as antibacterial agents for the treatment of infected wounds. PMID:24804249

Novel semisynthetic antibiotics from caprazamycins A-G: caprazene derivatives and their antibacterial activity.

PubMed

Takahashi, Yoshiaki; Igarashi, Masayuki; Miyake, Toshiaki; Soutome, Hiromi; Ishikawa, Kanae; Komatsuki, Yasuhiro; Koyama, Yoshiko; Nakagawa, Naoko; Hattori, Seiko; Inoue, Kunio; Doi, Norio; Akamatsu, Yuzuru

2013-03-01

Acidic treatment of a mixture of caprazamycins (CPZs) A-G isolated from a screen of novel antimycobacterial agents gave caprazene, a core structure of CPZs, in high yield. Chemical modification of the resulting caprazene was performed to give its various derivatives. The structure-activity relationships of the caprazene derivatives against several mycobacterial species and pathogenic Gram-positive and Gram-negative bacteria were studied. Although caprazene showed no antibacterial activity, the antibacterial activity was restored for its 1'''-alkylamide, 1'''-anilide and 1'''-ester derivatives. Compounds 4b (CPZEN-45), 4d (CPZEN-48), 4f and 4g (CPZEN-51) exhibited more potent activities against Mycobacterium tuberculosis and M. avium complex strains than CPZ-B. These results suggest that caprazene would be a good precursor from which novel semisynthetic antibacterial antibiotics can be designed for the treatment of mycobacterial diseases such as tuberculosis and M. avium complex infection.

Trichoderma koningii assisted biogenic synthesis of silver nanoparticles and evaluation of their antibacterial activity

NASA Astrophysics Data System (ADS)

Tripathi, R. M.; Gupta, Rohit Kumar; Shrivastav, Archana; Singh, M. P.; Shrivastav, B. R.; Singh, Priti

2013-09-01

The present study demonstrates the biosynthesis of silver nanoparticles using Trichoderma koningii and evaluation of their antibacterial activity. Trichoderma koningii secretes proteins and enzymes that act as reducing and capping agent. The biosynthesized silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD). UV-Vis spectra showed absorbance peak at 413 nm corresponding to the surface plasmon resonance of silver nanoparticles. DLS was used to find out the size distribution profile. The size and morphology of the AgNPs was determined by TEM, which shows the formation of spherical nanoparticles in the size range of 8-24 nm. X-ray diffraction showed intense peaks corresponding to the crystalline silver. The antibacterial activity of biosynthesized AgNPs was evaluated by growth curve and inhibition zone and it was found that the AgNPs show potential effective antibacterial activity.

Shrink-induced superhydrophobic and antibacterial surfaces in consumer plastics.

PubMed

Freschauf, Lauren R; McLane, Jolie; Sharma, Himanshu; Khine, Michelle

2012-01-01

Structurally modified superhydrophobic surfaces have become particularly desirable as stable antibacterial surfaces. Because their self-cleaning and water resistant properties prohibit bacteria growth, structurally modified superhydrophobic surfaces obviate bacterial resistance common with chemical agents, and therefore a robust and stable means to prevent bacteria growth is possible. In this study, we present a rapid fabrication method for creating such superhydrophobic surfaces in consumer hard plastic materials with resulting antibacterial effects. To replace complex fabrication materials and techniques, the initial mold is made with commodity shrink-wrap film and is compatible with large plastic roll-to-roll manufacturing and scale-up techniques. This method involves a purely structural modification free of chemical additives leading to its inherent consistency over time and successive recasting from the same molds. Finally, antibacterial properties are demonstrated in polystyrene (PS), polycarbonate (PC), and polyethylene (PE) by demonstrating the prevention of gram-negative Escherichia coli (E. coli) bacteria growth on our structured plastic surfaces.

Preparation, characterization and antibacterial activity of oxidized κ-carrageenan.

PubMed

Zhu, Mingjin; Ge, Liming; Lyu, Yongbo; Zi, Yaxin; Li, Xinying; Li, Defu; Mu, Changdao

2017-10-15

The oxidized κ-carrageenans with different oxidation levels were prepared through the hydrogen peroxide and copper sulfate redox system. The oxidation level of oxidized κ-carrageenan was successfully controlled by adjusting the dosage of hydrogen peroxide. The results showed that the microtopography of oxidized κ-carrageenan changed from rough granules to smooth flakes, mainly resulting from the easily melting property of oxidized κ-carrageenan induced by introduced carboxyl and aldehyde groups. Especially, the antibacterial activity of oxidized κ-carrageenans against Gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) was systematically investigated. The results showed that the oxidized κ-carrageenan could damage the bacterial cell wall and cytoplasmic membrane and suppress the growth of both Gram-positive and Gram-negative bacteria. The oxidized κ-carrageenan possessed broad-spectrum antibacterial activity, which may be used as a new antibacterial agent. Copyright © 2017 Elsevier Ltd. All rights reserved.

In situ synthesis of silver nanoparticles uniformly distributed on polydopamine-coated silk fibers for antibacterial application.

PubMed

Lu, Zhisong; Xiao, Jing; Wang, Ying; Meng, Mei

2015-08-15

Fabrication of silver nanoparticles (AgNPs)-modified silk for antibacterial application is one of the hottest topics in the textile material research. However, the utilization of a polymer as both 3-dimensional matrix and reductant for the in-situ synthesis of AgNPs on silk fibers has not been realized. In this work, a facile, efficient and green approach was developed to in-situ grow AgNPs on the polydopamine (PDA)-functionalized silk. AgNPs with the size of 30-90 nm were uniformly deposited on the silk fiber surface with the PDA coating layer as a reduction reagent. The AgNPs exhibit excellent face-centered cubic crystalline structures. The bacterial growth curve and inhibition zone assays clearly demonstrate the antibacterial properties of the functionalized silk. Both high Ag(+) release level and long-time release profile were observed for the as-prepared AgNPs-PDA-coated silk, indicating the high-density loading of AgNPs and the possible long-term antibacterial effects. This work may provide a new method for the preparation of AgNPs-functionalized silk with antibacterial activity for the clothing and textile industry. Copyright © 2015 Elsevier Inc. All rights reserved.

[Topical problems of empiric therapy of community-acquired pneumonia in outpatient practice].

PubMed

Stepanova, I I; Chorbinskaya, S A; Baryshnikonva, G A; Nikiforova, N V; Pokutniy, N F; Zverkov, I V; Maslovskyi, L V; Kotenko, K V

2016-01-01

Community-acquired pneumonia is one of prevalent infectious respiratory diseases. Adequate treatment of community-acquired pneumonia, with consideration of the disease severity and microbial resistence, remains extremely topical. The article covers contemporary views of community-acquired pneumonia treatment standards. The authors described results of personal research aimed to study antibacterial treatment for community-acquired pneumonia on outpatient basis over 2004-2012, evaluated correspondence of the treatment to the national clinical recommendations.

Synthesis and Larvicidal and Adult Topical Activity of Some Hydrazide-Hydrazone Derivatives Against Aedes aegypti

DTIC Science & Technology

2014-01-01

anticancer, antifungal, antiviral, antitumoral, antibacterial and antimalarial activities [11-13]. Recently, our group has been investigating the...ABSTRACT A series of novel hydrazide-hydrazone derivatives were synthesized and evaluated for their larvicidal and adult topical activity against...4b) showed noteworthy larvacidal activity against Aedes aegypti. Dose-response data of compound 4b showed LC50 and LC90 values of 30.5 (15.4 – 22.7

The Wound Healing and Antibacterial Activity of Five Ethnomedical Calophyllum inophyllum Oils: An Alternative Therapeutic Strategy to Treat Infected Wounds

PubMed Central

Léguillier, Teddy; Lecsö-Bornet, Marylin; Lémus, Christelle; Rousseau-Ralliard, Delphine; Lebouvier, Nicolas; Hnawia, Edouard; Nour, Mohammed; Aalbersberg, William; Ghazi, Kamelia; Raharivelomanana, Phila; Rat, Patrice

2015-01-01

Background Calophyllum inophyllum L. (Calophyllaceae) is an evergreen tree ethno-medically used along the seashores and islands of the Indian and Pacific Oceans, especially in Polynesia. Oil extracted from the seeds is traditionally used topically to treat a wide range of skin injuries from burn, scar and infected wounds to skin diseases such as dermatosis, urticaria and eczema. However, very few scientific studies reported and quantified the therapeutic properties of Calophyllum inophyllum oil (CIO). In this work, five CIO from Indonesia (CIO1), Tahiti (CIO2, 3), Fiji islands (CIO4) and New Caledonia (CIO5) were studied and their cytotoxic, wound healing, and antibacterial properties were presented in order to provide a scientific support to their traditional use and verify their safety. Methods The safety of the five CIO was ascertained using the Alamar blue assay on human keratinocyte cells. CIO wound healing properties were determined using the scratch test assay on human keratinocyte cells. CIO-stimulated antibacterial innate immune response was evaluated using ELISA by measuring β defensin-2 release in human derivative macrophage cells. CIO antibacterial activity was tested using oilogramme against twenty aerobic Gram- bacteria species, twenty aerobic Gram+ bacteria species, including a multi-drug resistant Staphylococcus aureus strain and two anaerobic Gram+ bacteria species e.g. Propionibacterium acnes and Propionibacterium granulosum. To detect polarity profile of the components responsible of the antibacterial activity, we performed bioautography against a Staphylococcus aureus strain. Results Based on Alamar Blue assay, we showed that CIO can be safely used on keratinocyte cells between 2.7% and 11.2% depending on CIO origin. Concerning the healing activity, all the CIO tested accelerated in vitro wound closure, the healing factor being 1.3 to 2.1 higher compared to control when keratinocytes were incubated after scratch with CIO at 0.1%. Furthermore, our results showed that CIO exhibit two distinct antibacterial effects: one against Gram+ bacteria by direct inhibition of mitotic growth and another potent effect against Gram- bacteria due to increased release of β-defensin 2 peptide by macrophages. Interestingly, the needed concentrations of CIO to inhibit bacteria growth and to promote wound healing are lower than concentrations exhibiting cytotoxic effects on keratinocyte cells. Finally, we performed bioautography assay against Staphylococcus aureus to determine polarity profile of the components responsible for CIO antibacterial activity. Our results showed for the five tested CIO that components responsible of the bacterial growth inhibition are the more polar one on the TLC chromatographic profile and are contained in the resinous fraction of the oil. Conclusions This study was conducted to evaluate cytotoxicity, wound healing and antibacterial properties of five CIO traditionally used to treat infected wounds. Using cell and bacteria cultures, we confirmed the pharmacological effects of CIO as wound healing and antimicrobial agent. Moreover, we showed that concentration of CIO needed to exhibit therapeutic effects are lower than concentrations exhibiting cytotoxic effects in vitro. For the first time, this study provides support for traditional uses of CIO. These wound healing and antibiotic properties make CIO a valuable candidate to treat infected wounds especially in tropical areas. PMID:26406588

The Wound Healing and Antibacterial Activity of Five Ethnomedical Calophyllum inophyllum Oils: An Alternative Therapeutic Strategy to Treat Infected Wounds.

PubMed

Léguillier, Teddy; Lecsö-Bornet, Marylin; Lémus, Christelle; Rousseau-Ralliard, Delphine; Lebouvier, Nicolas; Hnawia, Edouard; Nour, Mohammed; Aalbersberg, William; Ghazi, Kamelia; Raharivelomanana, Phila; Rat, Patrice

2015-01-01

Calophyllum inophyllum L. (Calophyllaceae) is an evergreen tree ethno-medically used along the seashores and islands of the Indian and Pacific Oceans, especially in Polynesia. Oil extracted from the seeds is traditionally used topically to treat a wide range of skin injuries from burn, scar and infected wounds to skin diseases such as dermatosis, urticaria and eczema. However, very few scientific studies reported and quantified the therapeutic properties of Calophyllum inophyllum oil (CIO). In this work, five CIO from Indonesia (CIO1), Tahiti (CIO2, 3), Fiji islands (CIO4) and New Caledonia (CIO5) were studied and their cytotoxic, wound healing, and antibacterial properties were presented in order to provide a scientific support to their traditional use and verify their safety. The safety of the five CIO was ascertained using the Alamar blue assay on human keratinocyte cells. CIO wound healing properties were determined using the scratch test assay on human keratinocyte cells. CIO-stimulated antibacterial innate immune response was evaluated using ELISA by measuring β defensin-2 release in human derivative macrophage cells. CIO antibacterial activity was tested using oilogramme against twenty aerobic Gram- bacteria species, twenty aerobic Gram+ bacteria species, including a multi-drug resistant Staphylococcus aureus strain and two anaerobic Gram+ bacteria species e.g. Propionibacterium acnes and Propionibacterium granulosum. To detect polarity profile of the components responsible of the antibacterial activity, we performed bioautography against a Staphylococcus aureus strain. Based on Alamar Blue assay, we showed that CIO can be safely used on keratinocyte cells between 2.7% and 11.2% depending on CIO origin. Concerning the healing activity, all the CIO tested accelerated in vitro wound closure, the healing factor being 1.3 to 2.1 higher compared to control when keratinocytes were incubated after scratch with CIO at 0.1%. Furthermore, our results showed that CIO exhibit two distinct antibacterial effects: one against Gram+ bacteria by direct inhibition of mitotic growth and another potent effect against Gram- bacteria due to increased release of β-defensin 2 peptide by macrophages. Interestingly, the needed concentrations of CIO to inhibit bacteria growth and to promote wound healing are lower than concentrations exhibiting cytotoxic effects on keratinocyte cells. Finally, we performed bioautography assay against Staphylococcus aureus to determine polarity profile of the components responsible for CIO antibacterial activity. Our results showed for the five tested CIO that components responsible of the bacterial growth inhibition are the more polar one on the TLC chromatographic profile and are contained in the resinous fraction of the oil. This study was conducted to evaluate cytotoxicity, wound healing and antibacterial properties of five CIO traditionally used to treat infected wounds. Using cell and bacteria cultures, we confirmed the pharmacological effects of CIO as wound healing and antimicrobial agent. Moreover, we showed that concentration of CIO needed to exhibit therapeutic effects are lower than concentrations exhibiting cytotoxic effects in vitro. For the first time, this study provides support for traditional uses of CIO. These wound healing and antibiotic properties make CIO a valuable candidate to treat infected wounds especially in tropical areas.

Ocular delivery systems for topical application of anti-infective agents.

PubMed

Duxfield, Linda; Sultana, Rubab; Wang, Ruokai; Englebretsen, Vanessa; Deo, Samantha; Rupenthal, Ilva D; Al-Kassas, Raida

2016-01-01

For the treatment of anterior eye segment infections using anti-infective agents, topical ocular application is the most convenient route of administration. However, topical delivery of anti-infective agents is associated with a number of problems and challenges owing to the unique structure of the eye and the physicochemical properties of these compounds. Topical ocular drug delivery systems can be classified into two forms: conventional and non-conventional. The efficacy of conventional ocular formulations is limited by poor corneal retention and permeation resulting in low ocular bioavailability. Recently, attention has been focused on improving topical ocular delivery of anti-infective agents using advanced drug delivery systems. This review will focus on the challenges of efficient topical ocular delivery of anti-infective agents and will discuss the various types of delivery systems used to improve the treatment anterior segment infections.

Using pullulan-based edible coatings to extend shelf-life of fresh-cut 'Fuji' apples.

PubMed

Wu, Shengjun; Chen, Jinhua

2013-04-01

Pullulan is a thickener that can form semipermeable films, and glutathione is an effective reducing agent, while chitooligosaccharide has antibacterial activity. In this study, effect of pullulan-based coatings in combination with antibrowning and antibacterial agents (1% pullulan; 0.8% glutathione+1% chitooligosaccharides; and 0.8% glutathione+1% chitooligosaccharides+1% pullulan) on apple slices was investigated during hypothermia storage. Pullulan-coating treatments effectively retarded enzymatic browning, maintained firmness, decreased weight loss, and inhibited microbial growth and respiration rate of apple slices during hypothermia storage compared with that of the control (p<0.05). Results indicate that using pullulan-based coatings in combination with glutathione and chitooligosaccharides is a promising way to extend the shelf-life of apple slices. Copyright © 2013 Elsevier B.V. All rights reserved.

Recent advances on antimicrobial wound dressing: A review.

PubMed

Simões, Déborah; Miguel, Sónia P; Ribeiro, Maximiano P; Coutinho, Paula; Mendonça, António G; Correia, Ilídio J

2018-06-01

Skin and soft tissue infections (SSTIs) have high rates of morbidity and mortality associated. Despite the successful treatment of some SSTIs, those affecting the subcutaneous tissue, fascia, or muscle delay the healing process and can lead to life-threatening conditions. Therefore, more effective treatments are required to deal with such pathological situations. Recently, wound dressings loaded with antimicrobial agents emerged as viable options to reduce wound bacterial colonization and infection, in order to improve the healing process. In this review, an overview of the most prominent antibacterial agents incorporated in wound dressings along with their mode of action is provided. Furthermore, the recent advances in the therapeutic approaches used in the clinic and some future perspectives regarding antibacterial wound dressings are also discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Echinacea plants as antioxidant and antibacterial agents: From traditional medicine to biotechnological applications.

PubMed

Sharifi-Rad, Mehdi; Mnayer, Dima; Morais-Braga, Maria Flaviana Bezerra; Carneiro, Joara Nályda Pereira; Bezerra, Camila Fonseca; Coutinho, Henrique Douglas Melo; Salehi, Bahare; Martorell, Miquel; Del Mar Contreras, María; Soltani-Nejad, Azam; Uribe, Yoshie Adriana Hata; Yousaf, Zubaida; Iriti, Marcello; Sharifi-Rad, Javad

2018-05-10

The genus Echinacea consists of 11 taxa of herbaceous and perennial flowering plants. In particular, Echinacea purpurea (L.) Moench is widely cultivated all over the United States, Canada, and in Europe, exclusively in Germany, for its beauty and reported medicinal properties. Echinacea extracts have been used traditionally as wound healing to improve the immune system and to treat respiratory symptoms caused by bacterial infections. Echinacea extracts have demonstrated antioxidant and antimicrobial activities, and to be safe. This survey aims at reviewing the medicinal properties of Echinacea species, their cultivation, chemical composition, and the potential uses of these plants as antioxidant and antibacterial agents in foods and in a clinical context. Moreover, the factors affecting the chemical composition of Echinacea spp. are also covered. Copyright © 2018 John Wiley & Sons, Ltd.

Synthetic Approaches toward Monocyclic 3‐Amino‐β‐lactams

PubMed Central

Deketelaere, Sari; Van Nguyen, Tuyen; Stevens, Christian V.

2017-01-01

Abstract Due to the emerging resistance against classical β‐lactam‐based antibiotics, a growing number of bacterial infections has become harder to treat. This alarming tendency necessitates continued research on novel antibacterial agents. Many classes of β‐lactam antibiotics are characterized by the presence of the 3‐aminoazetidin‐2‐one core, which resembles the natural substrate of the target penicillin‐binding proteins. In that respect, this Review summarizes the different synthetic pathways toward this key structure for the development of new antibacterial agents. The most extensively applied methods for 3‐amino‐β‐lactam ring formation are discussed, in addition to a few less common strategies. Moreover, approaches to introduce the 3‐amino substituent after ring formation are also covered. PMID:28638759

Anti-Bacterial and Anti-Fungal Activity of Xanthones Obtained via Semi-Synthetic Modification of α-Mangostin from Garcinia mangostana.

PubMed

Narasimhan, Srinivasan; Maheshwaran, Shanmugam; Abu-Yousef, Imad A; Majdalawieh, Amin F; Rethavathi, Janarthanam; Das, Prince Edwin; Poltronieri, Palmiro

2017-02-12

The microbial contamination in food packaging has been a major concern that has paved the way to search for novel, natural anti-microbial agents, such as modified α-mangostin. In the present study, twelve synthetic analogs were obtained through semi-synthetic modification of α-mangostin by Ritter reaction, reduction by palladium-carbon (Pd-C), alkylation, and acetylation. The evaluation of the anti-microbial potential of the synthetic analogs showed higher bactericidal activity than the parent molecule. The anti-microbial studies proved that I E showed high anti-bacterial activity whereas I I showed the highest anti-fungal activity. Due to their microbicidal potential, modified α-mangostin derivatives could be utilized as active anti-microbial agents in materials for the biomedical and food industry.

Antimicrobial and Antifouling Polymeric Agents for Surface Functionalization of Medical Implants.

PubMed

Zeng, Qiang; Zhu, Yiwen; Yu, Bingran; Sun, Yujie; Ding, Xiaokang; Xu, Chen; Wu, Yu-Wei; Tang, Zhihui; Xu, Fu-Jian

2018-05-09

Combating implant-associated infections is an urgent demand due to the increasing numbers in surgical operations such as joint replacements and dental implantations. Surface functionalization of implantable medical devices with polymeric antimicrobial and antifouling agents is an efficient strategy to prevent bacterial fouling and associated infections. In this work, antimicrobial and antifouling branched polymeric agents (GPEG and GEG) were synthesized via ring-opening reaction involving gentamicin and ethylene glycol species. Due to their rich primary amine groups, they can be readily coated on the polydopamine-modified implant (such as titanium) surfaces. The resultant surface coatings of Ti-GPEG and Ti-GEG produce excellent in vitro antibacterial efficacy toward both Staphylococcus aureus and Escherichia coli, while Ti-GPEG exhibit better antifouling ability. Moreover, the infection model with S. aureus shows that implanted Ti-GPEG possessed excellent antibacterial and antifouling ability in vivo. This study would provide a promising strategy for the surface functionalization of implantable medical devices to prevent implant-associated infections.

Novel quercetin glycosides as potent anti-MRSA and anti-VRE agents.

PubMed

Hossion, Abugafar M L; Sasaki, Kenji

2013-12-01

Each year in the United States, at least 2 million people become infected with bacteria that are resistant to antibiotics and at least 23,000 people die each year as a direct result of these infections (Threat report 2013). Vancomycin is an FDA approved antibiotic and is growing importance in the treatment of hospital infections, with particular emphasis on its value to fight against methicillin-resistant Staphylococcus aureus (MRSA). The increasing use of vancomycin to treat infections caused by the Gram-positive MRSA in the 1970s selected for drug-resistant enterococci, less potent than staphylococci but opportunistic in the space vacated by other bacteria and in patients with compromised immune systems. The dramatic rise of antibiotic-resistant bacteria over the past two decades has stressed the need for completely novel classes of antibacterial agents. This paper reports the recent patent review on the strategy for finding novel quercetinglycoside type antibacterial agents against vancomycin-resistant bacterial strains.

Bad bugs, no drugs: no ESKAPE! An update from the Infectious Diseases Society of America.

PubMed

Boucher, Helen W; Talbot, George H; Bradley, John S; Edwards, John E; Gilbert, David; Rice, Louis B; Scheld, Michael; Spellberg, Brad; Bartlett, John

2009-01-01

The Infectious Diseases Society of America (IDSA) continues to view with concern the lean pipeline for novel therapeutics to treat drug-resistant infections, especially those caused by gram-negative pathogens. Infections now occur that are resistant to all current antibacterial options. Although the IDSA is encouraged by the prospect of success for some agents currently in preclinical development, there is an urgent, immediate need for new agents with activity against these panresistant organisms. There is no evidence that this need will be met in the foreseeable future. Furthermore, we remain concerned that the infrastructure for discovering and developing new antibacterials continues to stagnate, thereby risking the future pipeline of antibacterial drugs. The IDSA proposed solutions in its 2004 policy report, "Bad Bugs, No Drugs: As Antibiotic R&D Stagnates, a Public Health Crisis Brews," and recently issued a "Call to Action" to provide an update on the scope of the problem and the proposed solutions. A primary objective of these periodic reports is to encourage a community and legislative response to establish greater financial parity between the antimicrobial development and the development of other drugs. Although recent actions of the Food and Drug Administration and the 110th US Congress present a glimmer of hope, significant uncertainly remains. Now, more than ever, it is essential to create a robust and sustainable antibacterial research and development infrastructure--one that can respond to current antibacterial resistance now and anticipate evolving resistance. This challenge requires that industry, academia, the National Institutes of Health, the Food and Drug Administration, the Centers for Disease Control and Prevention, the US Department of Defense, and the new Biomedical Advanced Research and Development Authority at the Department of Health and Human Services work productively together. This report provides an update on potentially effective antibacterial drugs in the late-stage development pipeline, in the hope of encouraging such collaborative action.

Antimicrobial Effects of Garcinia Mangostana on Cariogenic Microorganisms.

PubMed

Janardhanan, Sunitha; Mahendra, Jaideep; Girija, A S Smiline; Mahendra, Little; Priyadharsini, Vijayashree

2017-01-01

Garcinia mangostana commonly called as Mangosteen fruit has been used as an antibacterial agent since age old times. The mangosteen pericarp has proven to have antibacterial effect, but the effect of the same on cariogenic organisms has not been explored. The present study was an attempt to gain a better understanding of the antibacterial effect of mangosteen pericarp on the cariogenic bacteria, to unravel the therapeutic potential for the same. The aim of the study was to assess the antibacterial efficacy of the crude chloroform extract of mangosteen pericarp against cariogenic bacteria. The study was done under laboratory settings using an in vitro design. The microorganisms namely Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius, Streptococcus oralis and Lactobacillus acidophilus were procured from American Type Cell Culture (ATCC) and Microbial Type Culture Collection (MTCC) were revived and lawn cultured. The antibacterial effect of mangosteen pericarp was tested using agar well diffusion method on Trypticase Soy Agar-Blood Agar (TSA-BA) and de Man, Rogosa and Sharpe (MRS) agar media. The standard antiplaque agent chlorhexidine was used as the positive control. This cross-sectional, experimental study was done in Central Research laboratory, Meenakshi Ammal Dental College for period of eight weeks. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values were determined by microbroth dilution method. Statistical analysis was done by calculating the mean of the zones of inhibition on tested microorganisms. Mann-Whitney test was done to compare the zones of inhibition of mangosteen and chlorhexidine. The antibacterial bioassay showed the highest activity for Lactobacillus acidophilus (13.6 mm) and Streptococcus sanguis (13.6 mm), whereas, it showed a medium and low activity for Streptococcus oralis (11.3 mm), Streptococcus mutans (10.6 mm) and Streptococcus salivarius (3 mm) respectively. The MBC and MIC values were lowest for Lactobacillus acidophilus (MIC 25 mg/ml, MBC 50 mg/ml) and Streptococcus oralis (MIC 50 mg/ml, MBC 100 mg/ml). Mangosteen pericarp extract had a higher zone of inhibition against the tested microorganisms which suggests its potent antibacterial action against cariogenic organisms. However, further analytical studies are needed to isolate the key molecules of mangosteen pericarp, to explore its anticariogenic therapeutic potential on gram negative oral microorganisms.

(PCG) Protein Crystal Growth Gamma-Interferon

NASA Technical Reports Server (NTRS)

1989-01-01

(PCG) Protein Crystal Growth Gamma-Interferon. Stimulates the body's immune system and is used clinically in the treatment of cancer. Potential as an anti-tumor agent against solid tumors as well as leukemia's and lymphomas. It has additional utility as an anti-ineffective agent, including antiviral, anti-bacterial, and anti-parasitic activities. Principal Investigator on STS-26 was Charles Bugg.

Effect of vehicles on topical application of aloe vera and arnica montana components.

PubMed

Bergamante, Valentina; Ceschel, Gian Carlo; Marazzita, Sergio; Ronchi, Celestino; Fini, Adamo

2007-10-01

In this study two types of gels and microemulsions are investigated for their ability to dissolve, release, and induce the permeation of helenalin, a flavonoid responsible for the anti-inflammatory activity of arnica montana extract, and aloin, an anthrone-C-glucosyls with antibacterial activity present in aloe vera extract. The release of these agents from each vehicle was followed by HPLC, and transcutaneous permeation was examined using a modified Franz cell and a porcine skin membrane. The study showed that a microemulsion can be a good vehicle to increase the permeation of helenalin, while the gel formulation, containing Sepigel 305, proved able to reduce the release and permeation of aloin, with a consequent activity limited to the surface of application, without any permeation. This is in accordance with the necessity to avoid this process, since human skin fibroblasts can metabolize absorbed aloin into a structurally related compound that increases the sensitivity of skin to ultraviolet light.

First step in the differential diagnosis of folliculitis: cytology.

PubMed

Durdu, Murat; Ilkit, Macit

2013-02-01

Folliculitis is a superficial inflammation of the hair follicles, and can be observed in individuals of any age or race. The incidence of folliculitis is unknown because most patients only consult a doctor in cases of increasing lesions. There are various infectious and non-infectious causes of folliculitis, and the most common causative agent is Staphylococcus aureus. In addition, several Gram-negative bacterial, fungal, parasitic, and viral pathogens can cause follicular papules and pustules. In routine practice, however, these lesions are usually thought to be bacterial. Therefore, topical and/or systemic antibacterial treatment is recommended, but this involves the risk of being misused for months or even years. Cytology, a simple, rapid, inexpensive, and repeatable diagnostic method, can reveal various bacterial, fungal, viral, and parasitic pathogens. This review discusses the use of clinical sampling and staining of cytologic samples for the differential diagnosis of folliculitis, cytologic findings, and the frequency with which dermatologists use cytology to diagnose folliculitis, particularly in the age of molecular biology and more expensive, sophisticated investigations.

Synergism of coumarins from the Chinese drug Zanthoxylum nitidum with antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Zuo, Guo-Ying; Wang, Chun-Juan; Han, Jun; Li, Yu-Qing; Wang, Gen-Chun

2016-12-15

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious therapeutic challenge in current clinic and new drug development. Natural coumarins have diverse bioactivities and the potential of resistance modifying effects. This study is to present in-depth evaluations of in vitro antimicrobial activities of four natural coumarins 5-geranyloxy-7-methoxycoumarin (Gm, 1), (5,7-dimethoxy-8-prenyloxycoumarin (artanin, Ar, 2)), isopimpinellin (Is, 3) and phellopterin (Ph, 4) from Zanthoxylum nitidum (Roxb.) DC. (Rutaceae) extracts, focusing on their potential restoration the activity of conventional antibacterial agents against clinical MRSA strains. Bioactivity-guided fractionation and spectral analyses were used to isolate the coumarins and identify the structures, respectively. The double broth microdilution method was used to assay the coumarins' alone activity. The classic checkerboard microdilution and dynamic time-killing methods were used to evaluate combinatory effects. The four plant coumarins Gm (1), Ar (2), Is (3) and Ph (4) were isolated and identified from Z. nitidum extracts. Coumarins 1-4 displayed promising inhibition against both MSSA and MRSA with minimal inhibitory concentrations (MICs) of 8-64µg/ml, but very weak against Gram-negative pathogen and yeast with MICs of 256 to ≥1024µg/ml. The geranyloxy and prenyloxy substitutions showed to be more active than the methoxy substitution on the coumarin skeletons. 1-4 also showing different extent of synergism with a total of eight conventional antibacterial agents, i.e. chloramphenicol (CL), gentamicin (CN), fosfomycin (FF), levofloxacin (LE), minocycline (MI), piperacillin/tazobactam (P/T), teicoplanin (TE) and vancomycin (VA) against ten clinical MRSA strains. Four to ten of the tested MRSA strains showed bacteriostatic synergy in the eleven combinations. The anti-MRSA modifying effects were related to different arrangement in the combinations with fractional inhibitory concentration indices (FICIs) from 0.187 to 1.125 and the three combinations CN (Is), CL (Ph) and MI (Gm) were the best ones. The enhancement of activity was also shown by 2-64 of dose reduction indices (DRIs) of the combined MICs, with VA (Ph) combination resulted the biggest DRI. The resistance of MRSA to antibacterial agents could be reversed in the combinations of CL (Gm or Ph), LE (Ph) and MI (Is) following the Clinical and Laboratory Standards Institute (CLSI) criteria. Six combinations P/T (Gm), TE (Ar), CN (Is), VA (Ph) and CL (Gm or Ph) also showed bactericidal synergy with Δlog 10 CFU/ml >2 at 24h incubation. The coumarins showed high potentiating effects of the antibacterial agents against multi-drug resistant SA. The resistance reversal effect of CL, LE and MI warrants further pharmacological investigation on combinatory therapy for the sake of fighting against MRSA infections. Copyright © 2016 Elsevier GmbH. All rights reserved.

Further characterization of Bacillus subtilis antibiotic biosensors and their use for antibacterial mode-of-action studies.

PubMed

Mariner, Katherine R; Ooi, Nicola; Roebuck, Deborah; O'Neill, Alex J; Chopra, Ian

2011-04-01

We further examined the usefulness of previously reported Bacillus subtilis biosensors for antibacterial mode-of-action studies. The biosensors could not detect the tRNA synthetase inhibitors mupirocin, indolmycin, and borrelidin, some inhibitors of peptidoglycan synthesis, and most membrane-damaging agents. However, the biosensors confirmed the modes of action of several RNA polymerase inhibitors and DNA intercalators and provided new insights into the possible modes of action of ciprofloxacin, anhydrotetracycline, corralopyronin, 8-hydroxyquinoline, and juglone.

Biological Activities and Secondary Metabolite Screening of Rumex hastatus Extract through Fourier Transform Infrared and Raman Spectroscopy.

PubMed

Andleeb, Saiqa; Naseer, Anum; Ali, Shaukat; Mustafa, Rozina Ghulam; Zafar, Atiya; Shafique, Irsa; Ihsan-Ul-Haq; Ismail, Muhammad; Saleem, Muhammad; Mansoor, Qaiser

2018-01-01

Human infectious diseases are caused by various pathogens including bacteria, fungi, viruses, parasites, and protozoans. These infectious agents are controlled by using synthetic drugs as well as natural sources. The aim of current study was to evaluate the antibacterial effect of Rumex hastatus against clinical bacterial pathogens. In current research antibacterial effect of Rumex hastatus was analyzed against seven clinical pathogenic bacteria such as Escherichia coli, Serratia marcescens, Streptococcus pyogenes, Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa through agar well diffusion method. The boiled extract was used for the phytochemical screening, antioxidant potential, thin layer chromatography, bio-autography, and spot screening. Genomic DNA was extracted to find the DNA protection effect of R. hastatus. Antibacterial results showed that diethyl ether extract has the maximum inhibition of S. pyogenes (9.66 ± 0.57 mm). Acetone and diethyl ether extracts showed moderate inhibition of K. pneumoniae (6.33 ± 1.52 mm and 5.66 ±1.15 mm) and S. aureus (6.33 ± 1.52 mm and 5.66 ± 0.57 mm). Similarly, chloroform extract indicated moderate inhibition of S. pyogenes (5.66 ± 1.15 mm). Ethanol extract had low or even no effect on the growth of bacteria. Genomic DNA extraction also encouraged the antibacterial effect of R. hastatus. Various phytochemical constituents such as ketoses, oligosaccharides, amino acids, amines, sugars, flavonoids, and antioxidant constituents were detected. TLC-Bioautography and spot screening results revealed the potential use of R. hustatus as an antibacterial agent. It was concluded that most of the tested fractions appeared as an important source for the discovery of new antimicrobial drugs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus.

PubMed

de Moraes, Ana Carolina Mazarin; Lima, Bruna Araujo; de Faria, Andreia Fonseca; Brocchi, Marcelo; Alves, Oswaldo Luiz

2015-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) has been responsible for serious hospital infections worldwide. Nanomaterials are an alternative to conventional antibiotic compounds, because bacteria are unlikely to develop microbial resistance against nanomaterials. In the past decade, graphene oxide (GO) has emerged as a material that is often used to support and stabilize silver nanoparticles (AgNPs) for the preparation of novel antibacterial nanocomposites. In this work, we report the synthesis of the graphene-oxide silver nanocomposite (GO-Ag) and its antibacterial activity against relevant microorganisms in medicine. GO-Ag nanocomposite was synthesized through the reduction of silver ions (Ag(+)) by sodium citrate in an aqueous GO dispersion, and was extensively characterized using ultraviolet-visible absorption spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The antibacterial activity was evaluated by microdilution assays and time-kill experiments. The morphology of bacterial cells treated with GO-Ag was investigated via transmission electron microscopy. AgNPs were well distributed throughout GO sheets, with an average size of 9.4±2.8 nm. The GO-Ag nanocomposite exhibited an excellent antibacterial activity against methicillin-resistant S. aureus, Acinetobacter baumannii, Enterococcus faecalis, and Escherichia coli. All (100%) MRSA cells were inactivated after 4 hours of exposure to GO-Ag sheets. In addition, no toxicity was found for either pristine GO or bare AgNPs within the tested concentration range. Transmission electronic microscopy images offered insights into how GO-Ag nanosheets interacted with bacterial cells. Our results indicate that the GO-Ag nanocomposite is a promising antibacterial agent against common nosocomial bacteria, particularly antibiotic-resistant MRSA. Morphological injuries on MRSA cells revealed a likely loss of viability as a result of the direct contact between bacteria and the GO-Ag sheets.

Anti-methicillin-resistance Staphylococcus aureus (MRSA) compounds from Bauhinia kockiana Korth. And their mechanism of antibacterial activity.

PubMed

Chew, Yik Ling; Mahadi, Adlina Maisarah; Wong, Kak Ming; Goh, Joo Kheng

2018-02-20

Bauhinia kockiana originates from Peninsular Malaysia and it is grown as a garden ornamental plant. Our previous study reported that this plant exhibited fairly strong antioxidant and antimicrobial activities. This paper focused on the assessment of the antibacterial activity of B. kockiana towards methicillin-resistance Staphylococcus aureus (MRSA), to purify and to identify the antibacterial compounds, and to determine the mechanism of antibacterial activity. Antibacterial activity of B. kockiana flower was evaluated qualitatively and quantitatively using disc diffusion assay and microbroth dilution method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of extracts were examined. Phytochemical analysis was performed to determine the classes of phytochemicals in the extracts. Bioactivity guided isolation was employed to purify the antibacterial agents and identified via various spectroscopy methods. Scanning electron microscopy (SEM) technique was used to evaluate the antibacterial mechanism of extract and compounds isolated. B. kockiana flower was found to exhibit fairly strong antibacterial activity towards both strains of MRSA bacteria used, MIC varies from 62.5-250 μg/mL. Tannins and flavonoids have been detected in the phytochemical analysis. Gallic acid and its ester derivatives purified from ethyl acetate extract could inhibit MRSA at 250-500 μg/mL. SEM revealed that the cells have undergone plasmolysis upon treatment with the extract and compounds. Tannins and polyphenols are the antibacterial components towards MRSA in B. kockiana. Massive leakage of the cell content observed in treated cells showed that the phytochemicals have changed the properties of the cell membranes. Amphiphilic nature of the compounds exhibited the antibacterial activity towards MRSA via three stages: (1) cell membrane attachment; (2) cell membrane fluidity modification; and (3) cell membrane structure disruption.

Trends and exceptions of physical properties on antibacterial activity for Gram-positive and Gram-negative pathogens.

PubMed

Brown, Dean G; May-Dracka, Tricia L; Gagnon, Moriah M; Tommasi, Ruben

2014-12-11

To better understand the difficulties surrounding the identification of novel antibacterial compounds from corporate screening collections, physical properties of ∼3200 antibacterial project compounds with whole cell activity against Gram-negative or Gram-positive pathogens were profiled and compared to actives found from high throughput (HTS) screens conducted on both biochemical and phenotypic bacterial targets. The output from 23 antibacterial HTS screens illustrated that when compared to the properties of the antibacterial project compounds, the HTS actives were significantly more hydrophobic than antibacterial project compounds (typically 2-4 log units higher), and furthermore, for 14/23 HTS screens, the average clogD was higher than the screening collection average (screening collection clogD = 2.45). It was found that the consequences of this were the following: (a) lead identification programs often further gained hydrophobic character with increased biochemical potency, making the separation even larger between the physicochemical properties of known antibacterial agents and the HTS active starting point, (b) the probability of plasma protein binding and cytotoxicity are often increased, and (c) cell-based activity in Gram-negative bacteria was severely limited or, if present, demonstrated significant efflux. Our analysis illustrated that compounds least susceptible to efflux were those which were highly polar and small in MW or very large and typically zwitterionic. Hydrophobicity was often the dominant driver for HTS actives but, more often than not, precluded whole cell antibacterial activity. However, simply designing polar compounds was not sufficient for antibacterial activity and pointed to a lack of understanding of complex and specific bacterial penetration mechanisms.

Antibacterial activity-guided purification and identification of a novel C-20 oxygenated ent-kaurane from Rabdosia serra (MAXIM.) HARA.

PubMed

Lin, Lianzhu; Zhu, Dashuai; Zou, Linwu; Yang, Bao; Zhao, Mouming

2013-08-15

The objective of this work was to conduct an activity-guided isolation of antibacterial compounds from Rabdosia serra. The ethanol extracts of R. serra leaf and stem were partitioned sequentially into petroleum ether, ethyl acetate, butanol and water fractions, respectively. The ethanol extract of leaf evidenced broad-spectrum antibacterial activity against gram-positive bacterial, including Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes. The ethyl acetate fractions of leaf and stem exhibited strong inhibition against gram-positive bacteria, and were then purified further. On the basis of antibacterial assay-guided purification, three phenolic compounds (rosmarinic acid, methyl rosmarinate and pedalitin) and four C-20 oxygenated ent-kauranes (effusanin E, lasiodin, rabdosichuanin D and a new compound namely effusanin F) were obtained, whose contents were determined by HPLC analysis. The broth microdilution method confirmed the important inhibition potential of C-20 oxygenated ent-kauranes with low minimum inhibitory concentration (MIC) values. Effusanin E, lasiodin and effusanin F could be useful for the development of new antibacterial agents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Durable antimicrobial cotton textiles coated sonochemically with ZnO nanoparticles embedded in an in-situ enzymatically generated bioadhesive.

PubMed

Salat, Marc; Petkova, Petya; Hoyo, Javier; Perelshtein, Ilana; Gedanken, Aharon; Tzanov, Tzanko

2018-06-01

An important preventive measure for providing a bacteria-free environment for the patients is the introduction of highly efficient and durable antibacterial textiles in hospitals. This work describes a single step sono-enzymatic process for coating of cotton medical textiles with antibacterial ZnO nanoparticles (NPs) and gallic acid (GA) to produce biocompatible fabrics with durable antibacterial properties. Cellulose substrates, however, need pre-activation to achieve sufficient stability of the NPs on their surface. Herein, this drawback is overcome by the simultaneous sonochemical deposition of ZnO NPs and the synthesis of a bio-based adhesive generated by the enzymatic cross-linking of GA in which the NPs were embedded. GA possesses the multiple functions of an antibacterial agent, a building block of the cross-linked phenolic network, and as a compound providing the safe contact of the coated materials with human skin. The ZnO NPs-GA coated fabrics maintained above 60% antibacterial efficacy even after 60 washing cycles at 75 °C hospital laundry regime. Copyright © 2018 Elsevier Ltd. All rights reserved.

Functionalized ZnO Nanoparticles with Gallic Acid for Antioxidant and Antibacterial Activity against Methicillin-Resistant S. aureus

PubMed Central

Lee, Joo Min; Choi, Kyong-Hoon; Min, Jeeeun; Kim, Ho-Joong; Jee, Jun-Pil; Park, Bong Joo

2017-01-01

In this study, we report a new multifunctional nanoparticle with antioxidative and antibacterial activities in vitro. ZnO@GA nanoparticles were fabricated by coordinated covalent bonding of the antioxidant gallic acid (GA) on the surface of ZnO nanoparticles. This addition imparts both antioxidant activity and high affinity for the bacterial cell membrane. Antioxidative activities at various concentrations were evaluated using a 2,2′-azino-bis(ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging method. Antibacterial activities were evaluated against Gram-positive bacteria (Staphylococcus aureus: S. aureus), including several strains of methicillin-resistant S. aureus (MRSA), and Gram-negative bacteria (Escherichia coli). The functionalized ZnO@GA nanoparticles showed good antioxidative activity (69.71%), and the bactericidal activity of these nanoparticles was also increased compared to that of non-functionalized ZnO nanoparticles, with particularly effective inhibition and high selectivity for MRSA strains. The results indicate that multifunctional ZnO nanoparticles conjugated to GA molecules via a simple surface modification process displaying both antioxidant and antibacterial activity, suggesting a possibility to use it as an antibacterial agent for removing MRSA. PMID:29099064

Antibacterial and Anti-inflammatory Activities of Ppc-1, Active Principle of the Cellular Slime Mold Polysphondylium pseudo-candidum.

PubMed

Azelmat, Jabrane; Fiorito, Serena; Genovese, Salvatore; Epifano, Francesco; Grenier, Daniel

2015-01-01

The diisopentenyloxy quinolobactin derivative 3-methylbut-2-enyl-4-methoxy-8-[(3-methylbut-2-enyl)oxy] quinoline-2-carboxylate, also named as Ppc-1, has been initially isolated from the fruiting bodies of the cellular slime mold Polysphondylium pseudo-candidum. Given that few data are available in the literature concerning the biological properties of this compound, this study was undertaken to evaluate its antibacterial and anti-inflammatory properties. Ppc-1 exerted antibacterial activity on the Gram negative periodontopathogen Porphyromonas gingivalis, while it had no such effect on the other bacterial species tested. The antibacterial activity of Ppc-1 appeared to result from its ability to permeate the cell membrane. Using the U937-3xκB-LUC human monocytic cell line, Ppc-1 was found to dose-dependently inhibit the lipopolysaccharide-induced NF-κB activation, a signaling pathway that has been associated with inflammatory mediator secretion. In conclusion, Ppc-1, by exhibiting a dual mode of action including antibacterial and anti-inflammatory activities, may represent a promising targeted therapeutic agent for periodontal diseases.

Antibacterial free fatty acids: activities, mechanisms of action and biotechnological potential.

PubMed

Desbois, Andrew P; Smith, Valerie J

2010-02-01

Amongst the diverse and potent biological activities of free fatty acids (FFAs) is the ability to kill or inhibit the growth of bacteria. The antibacterial properties of FFAs are used by many organisms to defend against parasitic or pathogenic bacteria. Whilst their antibacterial mode of action is still poorly understood, the prime target of FFA action is the cell membrane, where FFAs disrupt the electron transport chain and oxidative phosphorylation. Besides interfering with cellular energy production, FFA action may also result from the inhibition of enzyme activity, impairment of nutrient uptake, generation of peroxidation and auto-oxidation degradation products or direct lysis of bacterial cells. Their broad spectrum of activity, non-specific mode of action and safety makes them attractive as antibacterial agents for various applications in medicine, agriculture and food preservation, especially where the use of conventional antibiotics is undesirable or prohibited. Moreover, the evolution of inducible FFA-resistant phenotypes is less problematic than with conventional antibiotics. The potential for commercial or biomedical exploitation of antibacterial FFAs, especially for those from natural sources, is discussed.

Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

NASA Astrophysics Data System (ADS)

Jin, Tony; He, Yiping

2011-12-01

The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against Escherichia coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achieving more than 7 log reductions in bacterial counts. The antibacterial activity of MgO NP increased as the concentrations of MgO increased. A synergistic effect of MgO in combination with nisin was observed as well. However, the addition of ZnO NP to MgO NP did not enhance the antibacterial activity of MgO against both pathogens. Scanning electron microscopy was used to characterize the morphological changes of E. coli O157:H7 before and after antimicrobial treatments. It was revealed that MgO NP treatments distort and damage the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. These results suggest that MgO NP alone or in combination with nisin could potentially be used as an effective antibacterial agent to enhance food safety.

Diversity and antibacterial activity of culturable actinobacteria isolated from five species of the South China Sea gorgonian corals.

PubMed

Zhang, Xiao-Yong; He, Fei; Wang, Guang-Hua; Bao, Jie; Xu, Xin-Ya; Qi, Shu-Hua

2013-06-01

This study describes the diversity and antibacterial activity of culturable actinobacteria isolated from five species of gorgonian corals (Echinogorgia aurantiaca, Melitodes squamata, Muricella flexuosa, Subergorgia suberosa, and Verrucella umbraculum) collected in shallow water of the South China Sea. A total of 123 actinobacterial isolates were recovered using ten different isolation media, and assigned to 11 genera, including Streptomyces and Micromonospora as the dominant genera, followed by Nocardia, Verrucosispora, Nocardiopsis, Rhodococcus, Pseudonocardia, Agrococcus, Saccharomonospora, Saccharopolyspora and Dietzia. Comparable analysis indicated that the numbers of actinobacterial genera and isolates from the five gorgonian coral species varied significantly. It was found that 72 isolates displayed antibacterial activity against at least one indicator bacterium, and the antibacterial strains isolated from different gorgonians had almost the same proportion (~50 %). These results provide direct evidence for the hypotheses that gorgonian coral species contain large and diverse communities of actinobacteria, and suggest that many gorgonian-associated actinobacteria could produce some antibacterial agents to protect their hosts against pathogens. To our knowledge, this is the first report about the diversity of culturable actinobacteria isolated from gorgonian corals.

Antibacterial and phytochemical screening of Anethum graveolens, Foeniculum vulgare and Trachyspermum ammi

PubMed Central

Kaur, Gurinder J; Arora, Daljit S

2009-01-01

Background Anethum graveolens Linn., Foeniculum vulgare Mill. and Trachyspermum ammi L. are widely used traditional medicinal plants to treat various ailments. To provide a scientific basis to traditional uses of these plants, their aqueous and organic seed extracts, as well as isolated phytoconstituents were evaluated for their antibacterial potential. Methods Antibacterial activity of aqueous and organic seed extracts was assessed using agar diffusion assay, minimum inhibitory concentration and viable cell count studies; and their antibacterial effect was compared with some standard antibiotics. The presence of major phytoconstituents was detected qualitatively and quantitatively. The isolated phytoconstituents were subjected to disc diffusion assay to ascertain their antibacterial effect. Results Hot water and acetone seed extracts showed considerably good antibacterial activity against all the bacteria except Klebsiella pneumoniae and one strain of Pseudomonas aeruginosa. Minimum inhibitory concentration for aqueous and acetone seed extracts ranged from 20–80 mg/ml and 5–15 mg/ml respectively. Viable cell count studies revealed the bactericidal nature of the seed extracts. Statistical analysis proved the better/equal efficacy of some of these seed extracts as compared to standard antibiotics. Phytochemical analysis showed the presence of 2.80 – 4.23% alkaloids, 8.58 – 15.06% flavonoids, 19.71 – 27.77% tannins, 0.55–0.70% saponins and cardiac glycosides. Conclusion Antibacterial efficacy shown by these plants provides a scientific basis and thus, validates their traditional uses as homemade remedies. Isolation and purification of different phytochemicals may further yield significant antibacterial agents. PMID:19656417

Antibacterial Activity of Ethyl Acetate the Extract of Noni Fruit (Morinda citrifolia L.) Against Bacterial Spoilage in Fish

NASA Astrophysics Data System (ADS)

Nugraheni, E. R.; Adriani, G. R.; Munawaroh, H.

2017-04-01

Noni fruit (Morinda citrifolia L.) contains compounds that have potential as antibacterial agent. Antibacterial compounds produced noni fruit (M. citrifolia L.) can inhibit bacterial growth. This study was conducted to test the antibacterial activity of ethyl acetate extract of noni fruit (M. citrifolia L.) against spoilage bacterial in fish. Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli, Klebsiella oxytoca, and Enterobacter aerogenes isolates and examine antibacterial phytochemical profile. Extraction of noni compounds was done by maceration, followed by partition with ethyl acetate to obtain the soluble and insoluble ethyl acetate fraction. Previews result show that the ethyl acetate extract had very strong activity. Extraction process continued by separation and isolation used preparative thin layer chromatography method, so that obtained five isolates and mark them as A, B, C, D and E. Antibacterial activity assay performed on isolates A, B, C, D, and E with 20 and 30% concentration. The test results showed that isolates A could not be inhibit the growth of bacteria, isolates B, C, D, and E has antibacterial activity with weak to strong inhibition. Isolate B had the greatest inhibition activity against the B. cereus, whereas isolates E had the greatest inhibition activity against P. aeroginosa. MIC (Minimum Inhibitor Concentration) and MBC (Minimum Bactericidal Concentration) test result showed that MIC and MBC values could not be determined. Analysis of compounds by TLC showed that isolate B suspected contains coumarin or flavonoids compounds that have antibacterial activity.

Microbial glycolipoprotein-capped silver nanoparticles as emerging antibacterial agents against cholera.

PubMed

Gahlawat, Geeta; Shikha, Sristy; Chaddha, Baldev Singh; Chaudhuri, Saumya Ray; Mayilraj, Shanmugam; Choudhury, Anirban Roy

2016-02-01

With the increased number of cholera outbreaks and emergence of multidrug resistance in Vibrio cholerae strains it has become necessary for the scientific community to devise and develop novel therapeutic approaches against cholera. Recent studies have indicated plausibility of therapeutic application of metal nano-materials. Among these, silver nanoparticles (AgNPs) have emerged as a potential antimicrobial agent to combat infectious diseases. At present nanoparticles are mostly produced using physical or chemical techniques which are toxic and hazardous. Thus exploitation of microbial systems could be a green eco-friendly approach for the synthesis of nanoparticles having similar or even better antimicrobial activity and biocompatibility. Hence, it would be worth to explore the possibility of utilization of microbial silver nanoparticles and their conjugates as potential novel therapeutic agent against infectious diseases like cholera. The present study attempted utilization of Ochrobactrum rhizosphaerae for the production of AgNPs and focused on investigating their role as antimicrobial agents against cholera. Later the exopolymer, purified from the culture supernatant, was used for the synthesis of spherical shaped AgNPs of around 10 nm size. Further the exopolymer was characterized as glycolipoprotein (GLP). Antibacterial activity of the novel GLP-AgNPs conjugate was evaluated by minimum inhibitory concentration, XTT reduction assay, scanning electron microscopy (SEM) and growth curve analysis. SEM studies revealed that AgNPs treatment resulted in intracellular contents leakage and cell lysis. The potential of microbially synthesized nanoparticles, as novel therapeutic agents, is still relatively less explored. In fact, the present study first time demonstrated that a glycolipoprotein secreted by the O. rhizosphaerae strain can be exploited for production of AgNPs which can further be employed to treat infectious diseases. Although this type of polymer has been obtained earlier from marine fungi and bacteria, none of these reports have studied the role of this polymer in AgNPs synthesis and its application in cholera therapy. Interestingly, the microbial GLP-capped AgNPs exhibited antibacterial activity against V. cholerae comparable to ciprofloxacin. Thus the present study may open up new avenues for development of novel therapeutic agents for treatment of infectious diseases. Graphical abstract Development of novel therapeutic agents for treatment of cholera.

Reduction of serum TARC levels in atopic dermatitis by topical anti-inflammatory treatments.

PubMed

Yasukochi, Yumi; Nakahara, Takeshi; Abe, Takeru; Kido-Nakahara, Makiko; Kohda, Futoshi; Takeuchi, Satoshi; Hagihara, Akihito; Furue, Masutaka

2014-09-01

Serum thymus and activation-regulated chemokine (TARC) levels are associated with the disease activity of patients with atopic dermatitis (AD) and sensitively reflect short-term changes in skin conditions. The main treatment for AD is topical agent application. This study investigated the relationship between serum TARC levels and the dosage of topical agents, including corticosteroids and/or tacrolimus, in patients with AD. The serum TARC levels of 56 AD patients and the amounts of topical agents prescribed to them were investigated retrospectively. The weekly reduction in serum TARC levels and weekly dosage of topical agents among AD patients were compared and their associations were evaluated. The dosage of topical agents was closely related to serum TARC levels. One gram of strong rank steroid or the equivalent amount of steroid/tacrolimus is required to reduce serum TARC levels by 9.94 pg/mL weekly in moderate to severe AD patients. Higher initial TARC levels require more topical agent, which results in a more rapid decrease in TARC levels. The serum TARC levels and eosinophil numbers in peripheral blood are significantly correlated. Serum TARC level improvement and topical agent dosage are strongly correlated. TARC and eosinophil numbers are significantly correlated, but the wider range of TARC levels seems to be clinically more useful for monitoring AD severity. The serum TARC level is a very sensitive biomarker for monitoring the severity and treatment response in AD.

Strong and Nonspecific Synergistic Antibacterial Efficiency of Antibiotics Combined with Silver Nanoparticles at Very Low Concentrations Showing No Cytotoxic Effect.

PubMed

Panáček, Aleš; Smékalová, Monika; Kilianová, Martina; Prucek, Robert; Bogdanová, Kateřina; Večeřová, Renata; Kolář, Milan; Havrdová, Markéta; Płaza, Grażyna Anna; Chojniak, Joanna; Zbořil, Radek; Kvítek, Libor

2015-12-28

The resistance of bacteria towards traditional antibiotics currently constitutes one of the most important health care issues with serious negative impacts in practice. Overcoming this issue can be achieved by using antibacterial agents with multimode antibacterial action. Silver nano-particles (AgNPs) are one of the well-known antibacterial substances showing such multimode antibacterial action. Therefore, AgNPs are suitable candidates for use in combinations with traditional antibiotics in order to improve their antibacterial action. In this work, a systematic study quantifying the synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was performed. Employing the microdilution method as more suitable and reliable than the disc diffusion method, strong synergistic effects were shown for all tested antibiotics combined with AgNPs at very low concentrations of both antibiotics and AgNPs. No trends were observed for synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs, indicating non-specific synergistic effects. Moreover, a very low amount of silver is needed for effective antibacterial action of the antibiotics, which represents an important finding for potential medical applications due to the negligible cytotoxic effect of AgNPs towards human cells at these concentration levels.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata

PubMed Central

Li, Chunlei; Zhu, Jianhua; Wang, Yanqing; Chen, Yuyan; Song, Liyan; Zheng, Weiming; Li, Jingjing; Yu, Rongmin

2017-01-01

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25–100 °C) and pH resistant (pH 3–10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria. PMID:28661457

Structure elucidation and in silico docking studies of a novel furopyrimidine antibiotics synthesized by endolithic bacterium Actinomadura sp. AL2.

PubMed

Bhattacharjee, Kaushik; Kumar, Shakti; Palepu, Narasinga Rao; Patra, Pradeep Kumar; Rao, Kollipara Mohan; Joshi, Santa Ram

2017-09-20

On screening of endolithic actinobacteria from a granite rock sample of Meghalaya for antibacterial compound, a novel antibacterial compound CCp1 was isolated from the fermentation broth of Actinomadura sp. AL2. On purification of the compound based on chromatographic techniques followed by characterization with FT-IR, UV-visible, 1 H NMR, 13 C NMR and mass spectrometry, the molecular formula of the compound was generated as C 20 H 17 N 3 O 2 , a furopyrimidine derivative. In vitro antibacterial activity of the compound was evaluated against both Gram positive and negative bacteria by agar well diffusion assay. The compound had lowest MIC (2.00 µg/ml) for Bacillus subtilis and highest MIC (> 64 µg/ml) for Staphylococcus epidermidis and Pseudomonas aeruginosa. The study revealed that the compound has potential antibacterial activity. The mode of action of the antibacterial compound was evaluated through in silico studies for its ability to bind DNA gyrase, 30S RNA molecules, OmpF porins and N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU). The antibacterial compound demonstrated more favorable docking with DNA gyrase, 30S RNA molecules and OmpF porins than GlmU which support the antibacterial compound CCp1 can be as a promising broad spectrum antibiotic agent with "multitarget" characteristics.

Design, synthesis and antibacterial evaluation of honokiol derivatives.

PubMed

Wu, Bo; Fu, Su-Hong; Tang, Huan; Chen, Kai; Zhang, Qiang; Peng, Ai-Hua; Ye, Hao-Yu; Cheng, Xing-Jun; Lian, Mao; Wang, Zhen-Ling; Chen, Li-Juan

2018-02-15

Staphylococcus aureus is a major and dangerous human pathogen that causes a range of clinical manifestations of varying severity, and is the most commonly isolated pathogen in the setting of skin and soft tissue infections, pneumonia, suppurative arthritis, endovascular infections, foreign-body associated infections, septicemia, osteomyelitis, and toxic shocksyndrome. Honokiol, a pharmacologically active natural compound derived from the bark of Magnolia officinalis, has antibacterial activity against Staphylococcus aureus which provides a great inspiration for the discovery of potential antibacterial agents. Herein, honokiol derivatives were designed, synthesized and evaluated for their antibacterial activity by determining the minimum inhibitory concentration (MIC) against S. aureus ATCC25923 and Escherichia coli ATCC25922 in vitro. 7c exhibited better antibacterial activity than other derivatives and honokiol. The structure-activity relationships indicated piperidine ring with amino group is helpful to improve antibacterial activity. Further more, 7c showed broad spectrum antibacterial efficiency against various bacterial strains including eleven gram-positive and seven gram-negative species. Time-kill kinetics against S. aureus ATCC25923 in vitro revealed that 7c displayed a concentration-dependent effect and more rapid bactericidal kinetics better than linezolid and vancomycin with the same concentration. Gram staining assays of S. aureus ATCC25923 suggested that 7c could destroy the cell walls of bacteria at 1×MIC and 4×MIC. Copyright © 2017. Published by Elsevier Ltd.

Phytochemical screening, cytotoxicity and antibacterial activities of two Bangladeshi medicinal plants.

PubMed

Roy, Ajoy; Biswas, Subrata Kumar; Chowdhury, Anusua; Shill, Manik Chandra; Raihan, Sheikh Zahir; Muhit, Md Abdul

2011-10-01

The objectives of the present study were to investigate phytochemical screening and to assay cytotoxicity and antibacterial activities of ethanolic extracts of leaves of two medicinal plants, Aglaonema hookerianum Schott (Family: Araceae) and Lannea grandis Engl. (Family: Anacardiaceae) available in Bangladesh. The brine shrimp lethality bioassay showed that the ethanolic extracts of Aglaonema hookerianum and Lannea grandis possessed cytotoxic activities with LC50 5.25 (microg mL(-1)) and 5.75 (microg mL(-1)) and LC90 10.47 (microg mL(-1)) and 9.55 (microg mL(-1)), respectively. Two extracts obtained from leaves were examined for their antibacterial activities against some gram positive bacteria such as Bacillus subtilis, Bacillus megaterium and Staphylococcus aureus, also gram negative strains of Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae, Salmonella typhi, Salmonella paratyphi and Vibrio cholerae. Agar disc diffusion method was applied to observe the antibacterial efficacy of the extracts. Results indicated that both plant extracts (500 microg disc(-1)) displayed antibacterial activity against all of the tested microorganisms. These results were also compared with the zones of inhibition produced by commercially available standard antibiotic, Amoxicillin at concentration of 10 microg disc(-1). Observed antibacterial properties of the ethanolic extract of Aglaonema hookerianum Schott and Lannea grandis Engl. showed that both plants might be useful sources for the development of new potent antibacterial agents.

Enhanced antibacterial activity of silver-decorated sandwich-like mesoporous silica/reduced graphene oxide nanosheets through photothermal effect

NASA Astrophysics Data System (ADS)

Liu, Rong; Wang, Xuandong; Ye, Jun; Xue, Ximei; Zhang, Fangrong; Zhang, Huicong; Hou, Xuemei; Liu, Xiaolong; Zhang, Yun

2018-03-01

Drug resistance of bacteria has become a global health problem, as it makes conventional antibiotics less efficient. It is urgently needed to explore novel antibacterial materials and develop effective treatment strategies to overcome the drug resistance of antibiotics. Herein, we successfully synthesized silver decorated sandwich-like mesoporous silica/reduced graphene oxide nanosheets (rGO/MSN/Ag) as a novel antibacterial material through facile method. The rGO and Ag nanoparticles can be reduced in the reaction system without adding any other reductants. In addition, the rGO/MSN/Ag showed higher photothermal conversion capacity due to the modification of silver nanoparticles and exhibited excellent antibacterial activities against Pseudomonas putida, Escherichia coli and Rhodococcus at relatively low dosages, which was confirmed by the minimum inhibitory concentration (MIC) test. Meanwhile, the E. coli with a high concentration was selected for exposure using an 808 nm laser, and the antibacterial effect was obviously enhanced by the near-infrared irradiation induced photothermal effect. Moreover, the hepatocyte LO2 were used for the cytotoxicity evaluation, and the rGO/MSN/Ag showed low toxicity and were without detectable cytotoxicity at the antimicrobial dose. As the prepared rGO/MSN/Ag nanosheets have the advantages of low-cost and high antibacterial activity, they might be of promising and useful antibacterial agents for different applications.

[Cloning, prokaryotic expression and antibacterial assay of Tenecin gene encoding an antibacterial peptide from Tenebrio molitor].

PubMed

Liu, Ying; Jiang, Yu-xin; Li, Chao-pin

2011-12-01

To clone tenecin gene, an antibacterial peptide gene, from Tenebrio molitor for its prokaryotic expression and explore the molecular mechanism for regulating the expression of antibacterial peptide in Tenebrio molitor larvae. The antibacterial peptide was induced from the larvae of Tenebrio molitor by intraperitoneal injection of Escherichia coli DH-5α (1×10(8)/ml). RT-PCR was performed 72 h after the injection to clone Tenecin gene followed by sequencing and bioinformatic analysis. The recombinant expression vector pET-28a(+)-Tenecin was constructed and transformed into E. coli BL21(DE3) cells and the expression of tenecin protein was observed after IPTG induction. Tenecin expression was detected in transformed E.coli using SDS-PAGE after 1 mmol/L IPTG induction. Tenecin gene, which was about 255 bp in length, encoded Tenecin protein with a relative molecular mass of 9 kD. Incubation of E.coli with 80, 60, 40, and 20 µg/ml tenecin for 18 h resulted in a diameter of the inhibition zone of 25.1∓0.03, 20.7∓0.06, 17.2∓0.11 and 9.3∓0.04 mm, respectively. Tenecin protein possesses strong antibacterial activity against E. coli DH-5α, which warrants further study of this protein for its potential as an antibacterial agent in clinical application.

The effect of sodium hypochlorite application on the success of calcium hydroxide and mineral trioxide aggregate pulpotomies in primary teeth.

PubMed

Akcay, Merve; Sari, Saziye

2014-01-01

This study's purpose was to evaluate the success of calcium hydroxide (CH) and mineral trioxide aggregate (MTA) pulpotomies following the use of five percent sodium hypochlorite (NaOCl) as an antibacterial agent to clean the chamber prior to application of the pulpotomy agent. A total of 128 teeth were randomly divided into two pulpotomy groups (CH or MTA). The teeth in each pulpotomy group, CH and MTA, were further randomly divided into subgroups to receive either the NaOCl (experimental) or saline (control) cleaning agent prior to applying the pulpotomy agent. The treatments were followed clinically and radiographically for 12 months. The radiographic success rates were 84 percent for CH NaOCl, 74 percent for CH saline control, 97 percent for MTA NaOCl, and 100 percent for MTA saline control. There were no significant differences between the radiographic success rates in the CH and MTA subgroups (CH NaOCl-CH control and MTA NaOCl-MTA control); no significant differences were observed when comparing the CH NaOCl-MTA NaOCl groups and the CH NaOCl-MTA control groups. Use of sodium hypochlorite as an antibacterial agent prior to application of the pulpotomy agent improved the success of calcium hydroxide pulpotomies to equal the success of mineral trioxide aggregate pulpotomies for observation up to 12 months.

Antimicrobial Peptides Derived from Fusion Peptides of Influenza A Viruses, a Promising Approach to Designing Potent Antimicrobial Agents.

PubMed

Wang, Jingyu; Zhong, Wenjing; Lin, Dongguo; Xia, Fan; Wu, Wenjiao; Zhang, Heyuan; Lv, Lin; Liu, Shuwen; He, Jian

2015-10-01

The emergence and dissemination of antibiotic-resistant bacterial pathogens have spurred the urgent need to develop novel antimicrobial agents with different mode of action. In this respect, we turned several fusogenic peptides (FPs) derived from the hemagglutinin glycoproteins (HAs) of IAV into potent antibacterials by replacing the negatively or neutrally charged residues of FPs with positively charged lysines. Their antibacterial activities were evaluated by testing the MICs against a panel of bacterial strains including S. aureus, S. mutans, P. aeruginosa, and E. coli. The results showed that peptides HA-FP-1, HA-FP-2-1, and HA-FP-3-1 were effective against both Gram-positive and Gram-negative bacteria with MICs ranging from 1.9 to 16.0 μm, while the toxicities toward mammalian cells were low. In addition, the mode of action and the secondary structure of these peptides were also discussed. These data not only provide several potent peptides displaying promising potential in development as broad antimicrobial agents, but also present a useful strategy in designing new antimicrobial agents. © 2015 John Wiley & Sons A/S.

Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity

NASA Astrophysics Data System (ADS)

Aramwit, Pornanong; Bang, Nipaporn; Ratanavaraporn, Juthamas; Ekgasit, Sanong

2014-02-01

In this study, a `green chemistry' approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO- and NH2 + groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.

[Therapeutic efficacy of levofloxacin against a model of replicable Legionella pneumophila lung infection in DBA/2 mice].

PubMed

Kashimoto, Yoshinori; Kurosaka, Yuichi; Karibe, Yukie; Uoyama, Saori; Fujikawa, Katsuko; Namba, Kenji; Otani, Tsuyoshi; Yamaguchi, Keizo

2009-10-01

The in vitro and in vivo antibacterial activities of levofloxacin (LVFX), a quinolone antibacterial, against clinically isolated Legionella pneumophila were investigated in comparison with those of existing antimicrobial agents approved for legionnaires disease. The minimum inhibitory concentrations (MICs) of the agents against 42 strains of L. pneumophila isolated in Japan were determined using agar dilution methods with buffered starch yeast extract agar. MIC90 of LVFX was 0.03 microg/ml and this activity was similar to ciprofloxacin and pazufloxacin, and higher than telithromycin and minocycline. Therapeutic efficacy of LVFX was studied against a pneumonia model induced by intranasal of L. pneumophila strain suzuki serogoup 1 in DBA/2 mice. Therapeutic doses in mice were selected that would closely match human exposure profile, area under the concentration-time curve (AUC) for a human oral dose of LVFX at 500 mg once a day. LVFX decreased significantly the bacterial burden in the lungs from the next day of commencing treatment. These results, including in vitro antibacterial activity against clinical isolates and therapeutic efficacy of a humanized dosing regimen, provide good evidence to support the use of LVFX at 500 mg once a day for treating patient with legionnaires disease.

Antibacterial potential of silver nanoparticles synthesized using Madhuca longifolia flower extract as a green resource.

PubMed

Patil, Maheshkumar Prakash; Singh, Rahul Dheerendra; Koli, Prashant Bhimrao; Patil, Kalpesh Tumadu; Jagdale, Bapu Sonu; Tipare, Anuja Rajesh; Kim, Gun-Do

2018-05-25

The green and one-step synthesis of silver nanoparticles (AgNPs) has been proposed as simple and ecofriendly. In the present study, a flower extract of Madhuca longifolia was used for the reduction of silver nitrate into AgNPs, with phytochemicals from the flower extract as a reducing and stabilizing agents. The synthesized AgNPs were spherical and oval shaped and about 30-50 nm sizes. The appearance of a brown color in the reaction mixture is a primary indication of AgNPs formation, and it was confirmed by observing UV-visible spectroscopy peak at 436 nm. The Energy Dispersive X-ray spectra and X-ray diffraction analysis results together confirm that the synthesized nanoparticles contain silver and silver chloride nanoparticles. The Zeta potential analysis indicates presence of negative charges on synthesized AgNPs. The FT-IR study represents involvement of functional groups in AgNPs synthesis. Synthesized AgNPs shows potential antibacterial activity against Gram-positive and Gram-negative pathogens. M. longifolia flower is a good source for AgNPs synthesis and synthesized AgNPs are applicable as antibacterial agent in therapeutics. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effectiveness of Hypochlorous Acid to Reduce the Biofilms on Titanium Alloy Surfaces in Vitro

PubMed Central

Chen, Chun-Ju; Chen, Chun-Cheng; Ding, Shinn-Jyh

2016-01-01

Chemotherapeutic agents have been used as an adjunct to mechanical debridement for peri-implantitis treatment. The present in vitro study evaluated and compared the effectiveness of hypochlorous acid (HOCl), sodium hypochlorite (NaOCl), and chlorhexidine (CHX) at eliminating Gram-negative (E. coli and P. gingivalis) and Gram-positive (E. faecalis and S. sanguinis) bacteria. The effect of irrigating volume and exposure time on the antimicrobial efficacy of HOCl was evaluated, and a durability analysis was completed. Live/dead staining, morphology observation, alamarBlue assay, and lipopolysaccharide (LPS) detection were examined on grit-blasted and biofilm-contaminated titanium alloy discs after treatment with the three chemotherapeutic agents. The results indicated that HOCl exhibited better antibacterial efficacy with increasing irrigating volumes. HOCl achieved greater antibacterial efficacy as treatment time was increased. A decrease in antimicrobial effectiveness was observed when HOCl was unsealed and left in contact with the air. All the irrigants showed antibacterial activity and killed the majority of bacteria on the titanium alloy surfaces of biofilm-contaminated implants. Moreover, HOCl significantly lowered the LPS concentration of P. gingivalis when compared with NaOCl and CHX. Thus, a HOCl antiseptic may be effective for cleaning biofilm-contaminated implant surfaces. PMID:27447617

Intravenous Minocycline: A Review in Acinetobacter Infections.

PubMed

Greig, Sarah L; Scott, Lesley J

2016-10-01

Intravenous minocycline (Minocin ® ) is approved in the USA for use in patients with infections due to susceptible strains of Gram-positive and Gram-negative pathogens, including infections due to Acinetobacter spp. Minocycline is a synthetic tetracycline derivative that was originally introduced in the 1960s. A new intravenous formulation of minocycline was recently approved and introduced to address the increasing prevalence of multidrug-resistant (MDR) pathogens. Minocycline shows antibacterial activity against A. baumannii clinical isolates worldwide, and exhibits synergistic bactericidal activity against MDR and extensively drug-resistant (XDR) A. baumannii isolates when combined with other antibacterial agents. In retrospective studies, intravenous minocycline provided high rates of clinical success or improvement and was generally well tolerated among patients with MDR or carbapenem-resistant A. baumannii infections. While randomized clinical trial data would be useful to fully establish the place of minocycline in the management of these infections for which there are currently very few available options, clinical trials in patients with infections due to Acinetobacter spp. are difficult to perform. Nevertheless, current data indicate a potential role for intravenous minocycline in the treatment of patients MDR A. baumannii infections, particularly when combined with a second antibacterial agent (e.g. colistin).

Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

NASA Astrophysics Data System (ADS)

Khairul, Wan M.; Daud, Adibah Izzati; Ismail, Noraznawati

2018-02-01

In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N'-(4-nitrobenzoyl) thiourea (1), N-chitosan-N'-(4-chlorobenzoyl) thiourea (2), N-chitosan-N'-(4-methylbenzoyl) thiourea (3), N-chitosan-N'-(2-iodobenzoyl) thiourea (4), and N-chitosan-N'-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activity as they were able to inhibit both Gram-positive and Gram-negative bacteria. Therefore, 1-5 showed good antibacterial activity and have high potential to be further developed as active materials in pharmaceutical interests.

Mechanism of action of NB2001 and NB2030, novel antibacterial agents activated by beta-lactamases.

PubMed

Stone, Geoffrey W; Zhang, Qin; Castillo, Rosario; Doppalapudi, V Ramana; Bueno, Analia R; Lee, Jean Y; Li, Qing; Sergeeva, Maria; Khambatta, Gody; Georgopapadakou, Nafsika H

2004-02-01

Two potent antibacterial agents designed to undergo enzyme-catalyzed therapeutic activation were evaluated for their mechanisms of action. The compounds, NB2001 and NB2030, contain a cephalosporin with a thienyl (NB2001) or a tetrazole (NB2030) ring at the C-7 position and are linked to the antibacterial triclosan at the C-3 position. The compounds exploit beta-lactamases to release triclosan through hydrolysis of the beta-lactam ring. Like cephalothin, NB2001 and NB2030 were hydrolyzed by class A beta-lactamases (Escherichia coli TEM-1 and, to a lesser degree, Staphylococcus aureus PC1) and class C beta-lactamases (Enterobacter cloacae P99 and E. coli AmpC) with comparable catalytic efficiencies (k(cat)/K(m)). They also bound to the penicillin-binding proteins of S. aureus and E. coli, but with reduced affinities relative to that of cephalothin. Accordingly, they produced a cell morphology in E. coli consistent with the toxophore rather than the beta-lactam being responsible for antibacterial activity. In biochemical assays, they inhibited the triclosan target enoyl reductase (FabI), with 50% inhibitory concentrations being markedly reduced relative to that of free triclosan. The transport of NB2001, NB2030, and triclosan was rapid, with significant accumulation of triclosan in both S. aureus and E. coli. Taken together, the results suggest that NB2001 and NB2030 act primarily as triclosan prodrugs in S. aureus and E. coli.

Preparation, property of the complex of carboxymethyl chitosan grafted copolymer with iodine and application of it in cervical antibacterial biomembrane.

PubMed

Chen, Yu; Yang, Yumin; Liao, Qingping; Yang, Wei; Ma, Wanfeng; Zhao, Jian; Zheng, Xionggao; Yang, Yang; Chen, Rui

2016-10-01

Cervical erosion is one of the common diseases of women. The loop electrosurgical excisional procedure (LEEP) has been used widely in the treatment of the cervical diseases. However, there are no effective wound dressings for the postoperative care to protect the wound area from further infection, leading to increased secretion and longer healing time. Iodine is a widely used inorganic antibacterial agent with many advantages. However, the carrier for stable iodine complex antibacterial agents is lack. In the present study, a novel iodine carrier, Carboxymethyl chitosan-g-(poly(sodium acrylate)-co-polyvinylpyrrolidone) (CMCTS-g-(PAANa-co-PVP), was prepared by graft copolymerization of sodium acrylate (AANa) and N-vinylpyrrolidone (NVP) to a carboxymethyl chitosan (CMCTS) skeleton. The obtained structure could combine prominent property of poly(sodium acrylate) (PAANa) anionic polyelectrolyte segment and good complex property of polyvinylpyrrolidone (PVP) segment to iodine. The bioactivity of CMCTS could also be kept. The properties of the complex, CMCTS-g-(PAANa-co-PVP)-I2, were studied. The in vitro experiment shows that it has broad-spectrum bactericidal effects to virus, fungus, gram-positive bacteria and gram-negative bacteria. A CMCTS-g-(PAANa-co-PVP)-I2 complex contained cervical antibacterial biomembrane (CABM) was prepared. The iodine release from the CABM is pH-dependent. The clinic trial results indicate that CABM has better treatment effectiveness than the conventional treatment in the postoperative care of the LEEP operation. Copyright © 2016 Elsevier B.V. All rights reserved.

Anti-Propionibacterium acnes assay-guided purification of brazilin and preparation of brazilin rich extract from Caesalpinia sappan heartwood.

PubMed

Nirmal, Nilesh Prakash; Panichayupakaranant, Pharkphoom

2014-09-01

Caesalpinia sappan L. (Leguminosae or Fabaceae) heartwood has been used as a coloring agent, with antibacterial activity in food, beverages, cosmetics, and garments. To purify brazilin from C. sappan heartwood and use it as a standard marker for the preparation and standardization of an active constituent-rich extract. Crude ethanol extracts of C. sappan heartwood (CSE) were fractionated to isolate brazilin by an anti-P. acnes assay-guided isolation. Quantitative analysis was performed by HPLC. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the broth microdilution method. Brazilin isolated from CSE possessed antibacterial activity against P. acnes with MIC and MBC values of 15.6 and 31.2 µg/mL, respectively. Brazilin was, therefore, used as a standard marker for standardization and preparation of a brazilin rich extract (BRE). BRE was prepared from CSE using a simple one-step purification using a macroporous resin column eluted with 35% v/v ethanol. This method increased the brazilin content in the BRE up to 39.9% w/w. The antibacterial activity of the standardized BRE against acne involved bacteria was higher than for the CSE but lower than brazilin. However, for industrial applications, a large-scale one-step preparation of BRE has more advantages than the use of pure brazilin in terms of convenience and a low-cost production process. Therefore, BRE is considered as a potential coloring agent with antibacterial activity which is used for pharmaceutical, cosmetic, and nutraceutical applications.

The naphthoquinone diospyrin is an inhibitor of DNA gyrase with a novel mechanism of action.

PubMed

Karkare, Shantanu; Chung, Terence T H; Collin, Frederic; Mitchenall, Lesley A; McKay, Adam R; Greive, Sandra J; Meyer, Jacobus J M; Lall, Namrita; Maxwell, Anthony

2013-02-15

Tuberculosis and other bacterial diseases represent a significant threat to human health. The DNA topoisomerases are excellent targets for chemotherapy, and DNA gyrase in particular is a well-validated target for antibacterial agents. Naphthoquinones (e.g. diospyrin and 7-methyljuglone) have been shown to have therapeutic potential, particularly against Mycobacterium tuberculosis. We have found that these compounds are inhibitors of the supercoiling reaction catalyzed by M. tuberculosis gyrase and other gyrases. Our evidence strongly suggests that the compounds bind to the N-terminal domain of GyrB, which contains the ATPase active site, but are not competitive inhibitors of the ATPase reaction. We propose that naphthoquinones bind to GyrB at a novel site close to the ATPase site. This novel mode of action could be exploited to develop new antibacterial agents.

The Naphthoquinone Diospyrin Is an Inhibitor of DNA Gyrase with a Novel Mechanism of Action*

PubMed Central

Karkare, Shantanu; Chung, Terence T. H.; Collin, Frederic; Mitchenall, Lesley A.; McKay, Adam R.; Greive, Sandra J.; Meyer, Jacobus J. M.; Lall, Namrita; Maxwell, Anthony

2013-01-01

Tuberculosis and other bacterial diseases represent a significant threat to human health. The DNA topoisomerases are excellent targets for chemotherapy, and DNA gyrase in particular is a well-validated target for antibacterial agents. Naphthoquinones (e.g. diospyrin and 7-methyljuglone) have been shown to have therapeutic potential, particularly against Mycobacterium tuberculosis. We have found that these compounds are inhibitors of the supercoiling reaction catalyzed by M. tuberculosis gyrase and other gyrases. Our evidence strongly suggests that the compounds bind to the N-terminal domain of GyrB, which contains the ATPase active site, but are not competitive inhibitors of the ATPase reaction. We propose that naphthoquinones bind to GyrB at a novel site close to the ATPase site. This novel mode of action could be exploited to develop new antibacterial agents. PMID:23275348

Ga@C-dots as an antibacterial agent for the eradication of Pseudomonas aeruginosa

PubMed Central

Kumar, Vijay Bhooshan; Natan, Michal; Jacobi, Gila; Porat, Ze’ev; Banin, Ehud; Gedanken, Aharon

2017-01-01

The opportunistic pathogen Pseudomonas aeruginosa causes infections that are difficult to treat by antibiotic therapy. This research article reports on the synthesis of gallium (Ga) doped in carbon (C)-dots (Ga@C-dots) and their antimicrobial activity against free-living P. aeruginosa bacteria. The synthesis of Ga@C-dots was carried out by sonicating molten Ga (for 2.5 h) in polyethylene glycol-400, which acts as both a medium and carbon source. The resultant Ga@C-dots, having an average diameter of 9±2 nm, showed remarkably enhanced antibacterial activity compared with undoped C-dots. This was reflected by the much lower concentration of Ga doped within Ga@C-dots which was required for full inhibition of the bacterial growth. These results highlight the possibility of using Ga@C-dots as potential antimicrobial agents. PMID:28176980

Design, Synthesis, and Properties of a Potent Inhibitor of Pseudomonas aeruginosa Deacetylase LpxC.

PubMed

Piizzi, Grazia; Parker, David T; Peng, Yunshan; Dobler, Markus; Patnaik, Anup; Wattanasin, Som; Liu, Eugene; Lenoir, Francois; Nunez, Jill; Kerrigan, John; McKenney, David; Osborne, Colin; Yu, Donghui; Lanieri, Leanne; Bojkovic, Jade; Dzink-Fox, JoAnn; Lilly, Maria-Dawn; Sprague, Elizabeth R; Lu, Yipin; Wang, Hongming; Ranjitkar, Srijan; Xie, Lili; Wang, Bing; Glick, Meir; Hamann, Lawrence G; Tommasi, Ruben; Yang, Xia; Dean, Charles R

2017-06-22

Over the past several decades, the frequency of antibacterial resistance in hospitals, including multidrug resistance (MDR) and its association with serious infectious diseases, has increased at alarming rates. Pseudomonas aeruginosa is a leading cause of nosocomial infections, and resistance to virtually all approved antibacterial agents is emerging in this pathogen. To address the need for new agents to treat MDR P. aeruginosa, we focused on inhibiting the first committed step in the biosynthesis of lipid A, the deacetylation of uridyldiphospho-3-O-(R-hydroxydecanoyl)-N-acetylglucosamine by the enzyme LpxC. We approached this through the design, synthesis, and biological evaluation of novel hydroxamic acid LpxC inhibitors, exemplified by 1, where cytotoxicity against mammalian cell lines was reduced, solubility and plasma-protein binding were improved while retaining potent anti-pseudomonal activity in vitro and in vivo.

Trihydroxamate siderophore-fluoroquinolone conjugates are selective sideromycin antibiotics that target Staphylococcus aureus.

PubMed

Wencewicz, Timothy A; Long, Timothy E; Möllmann, Ute; Miller, Marvin J

2013-03-20

Siderophores are multidentate iron(III) chelators used by bacteria for iron assimilation. Sideromycins, also called siderophore-antibiotic conjugates, are a unique subset of siderophores that enter bacterial cells via siderophore uptake pathways and deliver the toxic antibiotic in a "Trojan horse" fashion. Sideromycins represent a novel antibiotic delivery technology with untapped potential for developing sophisticated microbe-selective antibacterial agents that limit the emergence of bacterial resistance. The chemical synthesis of a series of mono-, bis-, and trihydroxamate sideromycins are described here along with their biological evaluation in antibacterial susceptibility assays. The linear hydroxamate siderophores used for the sideromycins in this study were derived from the ferrioxamine family and inspired by the naturally occurring salmycin sideromycins. The antibacterial agents used were a β-lactam carbacepholosporin, Lorabid, and a fluoroquinolone, ciprofloxacin, chosen for the different locations of their biological targets, the periplasm (extracellular) and the cytoplasm (intracellular). The linear hydroxamate-based sideromycins were selectively toxic toward Gram-positive bacteria, especially Staphylococcus aureus SG511 (MIC = 1.0 μM for the trihydroxamate-fluoroquinolone sideromycin). Siderophore-sideromycin competition assays demonstrated that only the fluoroquinolone sideromycins required membrane transport to reach their cytoplasmic biological target and that a trihydroxamate siderophore backbone was required for protein-mediated active transport of the sideromycins into S. aureus cells via siderophore uptake pathways. This work represents a comprehensive study of linear hydroxamate sideromycins and teaches how to build effective hydroxamate-based sideromycins as Gram-positive selective antibiotic agents.

Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition

PubMed Central

Lu, Xiong; Zhang, Bailin; Wang, Yingbo; Zhou, Xianli; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio; Ding, Yonghui; Leng, Yang

2011-01-01

Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices. PMID:20880853

Antimicrobial activity of commercially available essential oils against Streptococcus mutans.

PubMed

Chaudhari, Lalit Kumar D; Jawale, Bhushan Arun; Sharma, Sheeba; Sharma, Hemant; Kumar, C D Mounesh; Kulkarni, Pooja Adwait

2012-01-01

Many essential oils have been advocated for use in complementary medicine for bacterial and fungal infections. However, few of the many claims of therapeutic efficacy have been validated adequately by either in vitro testing or in vivo clinical trials. To study the antibacterial activity of nine commercially available essential oils against Streptococcus mutans in vitro and to compare the antibacterial activity between each material. Nine pure essential oils; wintergreen oil, lime oil, cinnamon oil, spearmint oil, peppermint oil, lemongrass oil, cedarwood oil, clove oil and eucalyptus oil were selected for the study. Streptococcus mutans was inoculated at 37ºC and seeded on blood agar medium. Agar well diffusion assay was used to measure antibacterial activity. Zone of inhibition was measured around the filter paper in millimeters with vernier caliper. Cinnamon oil showed highest activity against Streptococcus mutans followed by lemongrass oil and cedarwood oil. Wintergreen oil, lime oil, peppermint oil and spearmint oil showed no antibacterial activity. Cinnamon oil, lemongrass oil, cedarwood oil, clove oil and eucalyptus oil exhibit antibacterial property against S. mutans. The use of these essential oils against S. mutans can be a viable alternative to other antibacterial agents as these are an effective module used in the control of both bacteria and yeasts responsible for oral infections.

Surface-independent antibacterial coating using silver nanoparticle-generating engineered mussel glue.

PubMed

Jo, Yun Kee; Seo, Jeong Hyun; Choi, Bong-Hyuk; Kim, Bum Jin; Shin, Hwa Hui; Hwang, Byeong Hee; Cha, Hyung Joon

2014-11-26

During implant surgeries, antibacterial agents are needed to prevent bacterial infections, which can cause the formation of biofilms between implanted materials and tissue. Mussel adhesive proteins (MAPs) derived from marine mussels are bioadhesives that show strong adhesion and coating ability on various surfaces even in wet environment. Here, we proposed a novel surface-independent antibacterial coating strategy based on the fusion of MAP to a silver-binding peptide, which can synthesize silver nanoparticles having broad antibacterial activity. This sticky recombinant fusion protein enabled the efficient coating on target surface and the easy generation of silver nanoparticles on the coated-surface under mild condition. The biosynthesized silver nanoparticles showed excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria and also revealed good cytocompatibility with mammalian cells. In this coating strategy, MAP-silver binding peptide fusion proteins provide hybrid environment incorporating inorganic silver nanoparticle and simultaneously mediate the interaction of silver nanoparticle with surroundings. Moreover, the silver nanoparticles were fully synthesized on various surfaces including metal, plastic, and glass by a simple, surface-independent coating manner, and they were also successfully synthesized on a nanofiber surface fabricated by electrospinning of the fusion protein. Thus, this facile surface-independent silver nanoparticle-generating antibacterial coating has great potential to be used for the prevention of bacterial infection in diverse biomedical fields.

Antibacterial activity of ethanolic extracts of some Vietnamese medicinal plants against Helicobacter pylori

NASA Astrophysics Data System (ADS)

Ngan, Luong Thi My; Dung, Pham Phuong; Nhi, Nguyen Vang Thi Yen; Hoang, Nguyen van Minh; Hieu, Tran Trung

2017-09-01

Helicobacter pylori is one of the most common human infectious bacteria. The infection is highly associated with a number of the most important disease of the upper gastrointestinal tract, including gastritis, duodenitis, peptic ulceration, and gastric cancer. In addition, widespread use of antimicrobial agents has resulted in the development of antibiotic resistance. Metabolites of plants, particularly higher plants, have been suggested as alternative potential sources for antibacterial products due to their safe. This study aimed to evaluate antibacterial activities of crude ethanolic extracts of seventeen Vietnamese medicinal plants toward one reference strain and three clinical isolates of Helicobacter pylori using broth micro-dilution bioassay. The antibacterial activities of these extracts were also compared with those of seven antibiotics, amoxicillin, clarithromycin, erythromycin, levofloxacin, azithromycin, tetracycline, and metronidazole. The extracts of Ampelopsis cantoniensis and Cleistocalyx operculatus showed highest antibacterial activity with MIC (MBC) values of 0.31 - 0.97 (2.5 - 5) mg/mL, followed by the extracts of Hedyotis diffusa and Ardisia silvestris with MIC (MBC) values of 1.04 - 1.94 (7.5 - 10) mg/mL. The remaining plant extracts exhibited moderate, low and very low or no active to the H. pylori strains. Further studies are needed to determine the active compounds from the extracts that showed high antibacterial activity against H. pylori.

Formulation and in vitro study of antibacterial vaginal suppositories.

PubMed

Regdon, G; Gombkötö, S; Regdon, G; Selmeczi, B

1994-12-01

Vaginal suppositories frequently used in gynaecological therapy were studied. Several antibacterial pharmacons are used for the topical treatment of vaginitis of various origins. In view of the fact that the liberation of the given active substance and the subsequent therapeutic effect may be improved or inhibited by the vehicle, our aim was to find the optimal suppository base for vaginal suppositories containing sulfadimidine, chloramphenicol and gentamicin sulfate by means of in vitro experiments. On the basis of breaking hardness, disintegration time and spreading properties the French Suppocire NA product, and compositions of macrogols with lower molecular weight proved to be the best lipophilic and hydrophilic bases, respectively. Among the lipophilic bases the in vitro drug liberation of Suppocire NA was significantly better (P < 0.05) than the other lipophilic bases. This vehicle is recommended for the topical treatment of vaginitis, as these suppositories have the further advantage that they can easily be produced on a magistral, galenical or industrial scale as well.

Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents

DTIC Science & Technology

2017-10-01

factor in the development of skin graft contraction. Using a porcine model of skin graft contraction, we will screen for anti- inflammatory agents (dose...Award Number: W81XWH-14-2-0153 TITLE: Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents ...09/14/2017 4. TITLE AND SUBTITLE “Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents ” 5a

Contact killing and antimicrobial properties of copper.

PubMed

Vincent, M; Duval, R E; Hartemann, P; Engels-Deutsch, M

2018-05-01

With the emergence of antibiotic resistance, the interest for antimicrobial agents has recently increased again in public health. Copper was recognized in 2008 by the United States Environmental Protection Agency (EPA) as the first metallic antimicrobial agent. This led to many investigations of the various properties of copper as an antibacterial, antifungal and antiviral agent. This review summarizes the latest findings about 'contact killing', the mechanism of action of copper nanoparticles and the different ways micro-organisms develop resistance to copper. © 2017 The Society for Applied Microbiology.

Effects of antibacterial primers with quaternary ammonium and nano-silver on S. mutans impregnated in human dentin blocks

PubMed Central

Cheng, Lei; Zhang, Ke; Weir, Michael D.; Liu, Huaibing; Zhou, Xuedong; Xu, Hockin H. K.

2013-01-01

Objectives Recent studies developed antibacterial bonding agents and composites containing a quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg). The objectives of this study were to investigate: (1) the effect of antibacterial primers containing QADM and NAg on the inhibition of Streptococcus mutans (S. mutans) impregnated into dentin blocks for the first time, and (2) the effect of QADM or NAg alone or in combination, and the effect of NAg mass fraction, on S. mutans viability in dentin. Methods Scotchbond Multi-Purpose (SBMP) bonding agent was used. QADM and NAg were incorporated into SBMP primer. Six primers were tested: SBMP primer control, control + 10% QADM (mass %), control + 0.05% NAg, control + 10% QADM + 0.05% NAg, control + 0.1% NAg, and control + 10% QADM + 0.1% NAg. S. mutans were impregnated into dentin blocks, then a primer was applied. The viable colony-forming units (CFU) were then measured by harvesting the bacteria in dentin using a sonication method. Results Control + 10% QADM + 0.1% NAg had bacteria inhibition zone 8-fold that of control (p < 0.05). The sonication method successfully harvested bacteria from dentin blocks. Control + 10% QADM + 0.1% NAg inhibited S. mutans in dentin blocks, reducing the viable CFU in dentin by three orders of magnitude, compared to control dentin without primer. Using QADM+NAg was more effective than QADM alone. Higher NAg content increased the potency. Dentin shear bond strength was similar for all groups (p > 0.1). Significance Antibacterial primer with QADM and NAg were shown to inhibit the S. mutans impregnated into dentin blocks for the first time. Bonding agent containing QADM and NAg is promising to eradicate bacteria in tooth cavity and inhibit caries. The QADM and NAg may have applicability to other adhesives, cements, sealants and composites. PMID:23422420

Purification and synergistic antibacterial activity of arginine derived cyclic dipeptides, from Achromobacter sp. associated with a rhabditid entomopathogenic nematode against major clinically relevant biofilm forming wound bacteria

PubMed Central

Deepa, Indira; Kumar, Sasidharan N.; Sreerag, Ravikumar S.; Nath, Vishnu S.; Mohandas, Chellapan

2015-01-01

Skin and chronic wound infections caused by various pathogenic bacteria are an increasing and urgent health problem worldwide. In the present investigation ethyl acetate extract of an Achromobacter sp. associated with a Rhabditis entomopathogenic nematode (EPN), displayed promising antibacterial property and was further purified by silica gel column chromatography to get three different cyclic dipeptides (CDPs). Based on the spectral data and Marfey's analyses, the CDPs were identified as cyclo(D-Leu-D-Arg) (1), cyclo(L-Trp-L-Arg) (2), and cyclo(D-Trp-D-Arg) (3), respectively. Three CDPs were active against all the 10 wound associated bacteria tested. The significant antibacterial activity was recorded by CDP 3, and highest activity of 0.5 μg/ml was recorded against Staphylococcus aureus and Pseudomonas aeruginosa. The synergistic antibacterial activities of CDPs and ampicillin were assessed using the checkerboard microdilution method. The results of the current study recorded that the combined effects of CDPs and ampicillin principally recorded synergistic activity. Interestingly, the combination of CDPs and ampicillin also recorded enhanced inhibition of biofilm formation by bacteria. Moreover, CDPs significantly stimulate the production of IL-10 and IL-4 (anti-inflammatory cytokines) by human peripheral blood mononuclear cells. CDPs do not make any significant effect on the production of pro-inflammatory cytokines like TNF-α. The three CDPs have been studied for their effect on intracellular S. aureus in murine macrophages (J774) using 24 h exposure to 0.5X, 1X, and 2X MIC concentrations. Significant decrease in intracellular S. aureus burden was recorded by CDPs. CDPs also recorded no cytotoxicity toward FS normal fibroblast, VERO, and L231 normal lung epithelial cell lines. Antimicrobial activity of the arginine containing CDPs against the wound associated bacteria is reported here for the first. Moreover, this is also the first report on the production of CDPs by Achromobacter sp. Finally, we conclude that the Achromobacter sp. is an incredibly promising source of natural bioactive secondary metabolites especially against wound pathogenic bacteria that may receive significant benefit in the field of human medicine in near future as topical agents. PMID:26379651

From Nano to Micro: using nanotechnology to combat microorganisms and their multidrug resistance.

PubMed

Natan, Michal; Banin, Ehud

2017-05-01

The spread of antibiotic resistance and increasing prevalence of biofilm-associated infections is driving demand for new means to treat bacterial infection. Nanotechnology provides an innovative platform for addressing this challenge, with potential to manage even infections involving multidrug-resistant (MDR) bacteria. The current review summarizes recent progress over the last 2 years in the field of antibacterial nanodrugs, and describes their unique properties, mode of action and activity against MDR bacteria and biofilms. Biocompatibility and commercialization are also discussed. As opposed to the more common division of nanoparticles (NPs) into organic- and inorganic-based materials, this review classifies NPs into two functional categories. The first includes NPs exhibiting intrinsic antibacterial properties and the second is devoted to NPs serving as a cargo for delivering antibacterial agents. Antibacterial nanomaterials used to decorate medical devices and implants are reviewed here as well. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Chromanyl-isoxazolidines as Antibacterial agents: Synthesis, Biological Evaluation, Quantitative Structure Activity Relationship, and Molecular Docking Studies.

PubMed

Singh, Gagandeep; Sharma, Anuradha; Kaur, Harpreet; Ishar, Mohan Paul S

2016-02-01

Regio- and stereoselective 1,3-dipolar cycloadditions of C-(chrom-4-one-3-yl)-N-phenylnitrones (N) with different mono-substituted, disubstituted, and cyclic dipolarophiles were carried out to obtain substituted N-phenyl-3'-(chrom-4-one-3-yl)-isoxazolidines (1-40). All the synthesized compounds were assayed for their in vitro antibacterial activity and display significant inhibitory potential; in particular, compound 32 exhibited good inhibitory activity against Salmonella typhymurium-1 & Salmonella typhymurium-2 with minimum inhibitory concentration value of 1.56 μg/mL and also showed good potential against methicillin-resistant Staphylococcus aureus with minimum inhibitory concentration 3.12 μg/mL. Quantitative structure activity relationship investigations with stepwise multiple linear regression analysis and docking simulation studies have been performed for validation of the observed antibacterial potential of the investigated compounds for determination of the most important parameters regulating antibacterial activities. © 2015 John Wiley & Sons A/S.

Historical and regulatory perspectives on the treatment effect of antibacterial drugs for community-acquired pneumonia.

PubMed

Singer, M; Nambiar, S; Valappil, T; Higgins, K; Gitterman, S

2008-12-01

A noninferiority margin based on the treatment effect of antibacterial drugs is required for noninferiority studies of community-acquired pneumonia. A quantitative estimate of treatment effect is generally determined from placebo-controlled trials, but, since the mid-to-late 1930s, no studies have compared outcomes for patients who received placebo (or no specific therapy) with those for patients who received an antibacterial drug for treatment of community-acquired pneumonia. In this article, early controlled studies, as well as observational data, are reviewed, and the beneficial effect of antibacterial drugs on mortality rates among patients with pneumococcal pneumonia is demonstrated. However, because these data were obtained in the early 20th century, several important factors have changed, including patient populations, the etiological agents of pneumonia, and medical standards of care. Thus, the applicability of these studies to the determination of a noninferiority margin for contemporary trials for community-acquired pneumonia remains in question.

Non-thermal hydrogen plasma processing effectively increases the antibacterial activity of graphene oxide

NASA Astrophysics Data System (ADS)

Ke, Zhigang; Ma, Yulong; Zhu, Zhongjie; Zhao, Hongwei; Wang, Qi; Huang, Qing

2018-01-01

Graphene-based materials (GMs) are promising antibacterial agents which provide an alternative route to treat pathogenic bacteria with resistance to conventional antibiotics. To further improve their antibacterial activity, many methods have been developed to functionalize the GMs with chemicals. However, the application of additional chemicals may pose potential risks to the environment and human being. Herein, a radio-frequency-driven inductively coupled non-thermal hydrogen plasma was used to treat and reduce graphene oxide (GO) without using any other chemicals, and we found that the plasma-reduced GO (prGO) is with significantly higher bactericidal activity against Escherichia coli. The mechanism of the increased antibacterial activity of prGO is due to that plasma processing breaks down the GO sheets into smaller layers with more rough surface defects, which can thus induce more destructive membrane damages to the bacteria. This work sets another good example, showing that plasma processing is a green and low-cost alternative for GM modification for biomedical applications.

Inhibition of the essential oil from Chenopodium ambrosioides L. and α-terpinene on the NorA efflux-pump of Staphylococcus aureus.

PubMed

de Morais Oliveira-Tintino, Cícera Datiane; Tintino, Saulo Relison; Limaverde, Paulo W; Figueredo, Fernando G; Campina, Fábia F; da Cunha, Francisco A B; da Costa, Roger H S; Pereira, Pedro Silvino; Lima, Luciene F; de Matos, Yedda M L S; Coutinho, Henrique Douglas Melo; Siqueira-Júnior, José P; Balbino, Valdir Q; da Silva, Teresinha Gonçalves

2018-10-01

This study was carried out to test the essential oil from C. ambrosioides leaves and its main constituent, α-Terpinene, in an antibacterial activity assay. As well, it was evaluated ability reduce resistance to norfloxacin and ethidium bromide was compared the Staphylococcus aureus 1199B whith 1199 wild type strain. The MIC of the C. ambrosioides essential oil and α-Terpinene were determined by microdilution method. The MIC of the essential oil and α-Terpinene presented a value ≥ 1024 μg/mL. However, when associated with antibacterials, the essential oil from C. ambrosioides leaves significantly reduced the MIC of antibiotics and ethidium bromide, characterizing an efflux pump inhibition. The C. ambrosioides essential oil, despite having no direct antibacterial activity against the S. aureus 1199B strain, showed a potentiating action when associated with antibacterial agents, this being attributed to an inhibition of efflux pumps. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

NASA Astrophysics Data System (ADS)

Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

2016-12-01

Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

Shrink-Induced Superhydrophobic and Antibacterial Surfaces in Consumer Plastics

PubMed Central

Freschauf, Lauren R.; McLane, Jolie; Sharma, Himanshu; Khine, Michelle

2012-01-01

Structurally modified superhydrophobic surfaces have become particularly desirable as stable antibacterial surfaces. Because their self-cleaning and water resistant properties prohibit bacteria growth, structurally modified superhydrophobic surfaces obviate bacterial resistance common with chemical agents, and therefore a robust and stable means to prevent bacteria growth is possible. In this study, we present a rapid fabrication method for creating such superhydrophobic surfaces in consumer hard plastic materials with resulting antibacterial effects. To replace complex fabrication materials and techniques, the initial mold is made with commodity shrink-wrap film and is compatible with large plastic roll-to-roll manufacturing and scale-up techniques. This method involves a purely structural modification free of chemical additives leading to its inherent consistency over time and successive recasting from the same molds. Finally, antibacterial properties are demonstrated in polystyrene (PS), polycarbonate (PC), and polyethylene (PE) by demonstrating the prevention of gram-negative Escherichia coli (E. coli) bacteria growth on our structured plastic surfaces. PMID:22916100

Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Antimicrobial Activity against E. coli ATCC 11775, S. maltophilia ATCC 13636 and S. enteritidis ATCC 13076.

PubMed

Huertas Méndez, Nataly De Jesús; Vargas Casanova, Yerly; Gómez Chimbi, Anyelith Katherine; Hernández, Edith; Leal Castro, Aura Lucia; Melo Diaz, Javier Mauricio; Rivera Monroy, Zuly Jenny; García Castañeda, Javier Eduardo

2017-03-12

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B-containing non-natural amino acids and the RWQWR motif were synthesized, purified, and characterized using RP-HPLC, MALDI-TOF mass spectrometry, and circular dichroism. The antibacterial activity of peptides against Escherichia coli ATCC 11775, Stenotrophomonas maltophilia ATCC 13636, and Salmonella enteritidis ATCC 13076 was evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. The synthetic bovine lactoferricin exhibited antibacterial activity against E. coli ATCC 11775 and S. enteritidis ATCC 13076. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strain. The monomeric, cyclic, tetrameric, and palindromic peptides containing the RWQWR motif exhibited high and specific activity against E. coli ATCC 11775. The results suggest that short peptides derived from lactoferricin B could be considered as potential candidates for the development of antibacterial agents against infections caused by E. coli .

Loaded Ce-Ag organic-inorganic hybrids and their antibacterial activity.

PubMed

Truffault, Laurianne; Rodrigues, Danilo Fernando; Salgado, Hérida Regida Nunes; Santilli, Celso Valentim; Pulcinelli, Sandra Helena

2016-11-01

There are requirements for surfaces with antibacterial properties in various technological fields. U-PEO hybrids with antibacterial properties were synthesized by the sol-gel process, incorporating combinations of cerium and silver salts at different silver molar fractions (0, 0.02, 0.05, 0.10, and 1) relative to the total amount of doped cations. The loaded hybrids were characterized by TGA, XRD, and Raman spectroscopy. Release tests were performed using UV-vis spectroscopy, and the antibacterial properties of the hybrids were studied in agar tests and turbidimetry assays. The nanostructural evolution of the hybrids during the release of the antibacterial agents was investigated by in situ SAXS. XRD results showed the presence of the AgCl crystalline phase in the loaded hybrids from a silver molar fraction of 0.05. Raman spectroscopy evidenced the interaction of silver cations with the polymeric part of the hybrid. SAXS results confirmed these interactions and showed that cerium species interacted with both organic and inorganic parts of the hybrids. The loaded U-PEO hybrids were found to release all the incorporated cerium in 1h, while the hybrid containing 100% of silver released only 78% of the incorporated silver. All the loaded hybrids displayed antibacterial activity against the Pseudomonas aeruginosa bacterium. The antibacterial activity was found to increase with silver molar fraction. Due to its high antibacterial activity and low silver molar fraction, the loaded hybrid with silver molar fraction of 0.10 seemed to be a good compromise between efficiency, esthetic transparency, and photostability. Copyright © 2016 Elsevier B.V. All rights reserved.

Isolation, enzyme-bound structure and antibacterial activity of platencin A[subscript 1] from Streptomyces platensis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Sheo B.; Ondeyka, John G.; Herath, Kithsiri B.

Natural products continue to serve as one of the best sources for discovery of antibacterial agents as exemplified by the recent discoveries of platensimycin and platencin. Chemical modifications as well as discovery of congeners are the main sources for gaining knowledge of structure-activity relationship of natural products. Screening for congeners in the extracts of the fermentation broths of Streptomyces platensis led to the isolation of platencin A{sub 1}, a hydroxy congener of platencin. The hydroxylation of the tricyclic enone moiety negatively affected the antibacterial activity and appears to be consistent with the hydrophobic binding pocket of the FabF. Isolation, structure,more » enzyme-bound structure and activity of platencin A{sub 1} and two other congeners have been described.« less

Potential antibacterial activity of some Saudi Arabia honey

PubMed Central

Hegazi, Ahmed G.; Guthami, Faiz M. Al; Gethami, Ahmed F. M. Al; Allah, Fyrouz M. Abd; Saleh, Ashraf A.; Fouad, Ehab A.

2017-01-01

Aim: The aim of this study was to investigate the potential antibacterial activity of some Saudi Arabia honey against selected bacterial strains of medical importance. Materials and Methods: A total of 10 Saudi Arabia honey used to evaluate their antimicrobial activity against some antibiotic-resistant pathogenic bacterial strains. The bacterial strains were Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa. Results: The antibacterial activity of Saudi honey against five bacterial strains showed different levels of inhibition according to the type of honey. The overall results showed that the potential activity was differing according to the pathogen and honey type. Conclusion: It could be concluded that the Saudi honey inhibit the growth of bacterial strains and that honey can be used as complementary antimicrobial agent against selected pathogenic bacteria. PMID:28344408

18β-Glycyrrhetinic Acid Derivatives Possessing a Trihydroxylated A Ring Are Potent Gram-Positive Antibacterial Agents.

PubMed

Huang, Li-Rong; Hao, Xiao-Jiang; Li, Qi-Ji; Wang, Dao-Ping; Zhang, Jian-Xin; Luo, Heng; Yang, Xiao-Sheng

2016-04-22

The oleanane-type triterpene 18β-glycyrrhetinic acid (1) was modified chemically through the introduction of a trihydroxylated A ring and an ester moiety at C-20 to enhance its antibacterial activity. Compounds 22, 23, 25, 28, 29, 31, and 32 showed more potent inhibitory activity against Streptomyces scabies than the positive control, streptomycin. Additionally, the inhibitory activity of the most potent compound, 29, against Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus was greater than that of the positive controls. The antibacterial mode of action of the active derivatives involved the regulation of the expression of genes associated with peptidoglycans, the respiratory metabolism, and the inherent virulence factors found in bacteria, as determined through a quantitative real-time reverse transcriptase PCR assay.

Design and synthesis of aloe-emodin derivatives as potent anti-tyrosinase, antibacterial and anti-inflammatory agents.

PubMed

Liu, Jinbing; Wu, Fengyan; Chen, Changhong

2015-11-15

Twenty aloe-emodin derivatives were designed, synthesized, and their biological activities were evaluated. Some compounds displayed potent tyrosinase inhibitory activities, especially, compounds with thiosemicarbazide moiety showed more potent inhibitory effects than the other compounds. The structure-activity relationships (SARs) were preliminarily discussed. The inhibition mechanism of selected compounds 1 and 13 were investigated. The results showed compound 1 was reversible inhibitor, however, compound 13 was irreversible. Kinetic analysis indicated that compound 1 was competitive tyrosinase inhibitor. Furthermore, the antibacterial activities and anti-inflammatory activities of some selected compounds were also screened. The results showed that compound 3 exhibited more potent antibacterial activity than the aloe-emodin, compounds 5 and 6 possessed more potent anti-inflammatory activities than the diacerein. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis and anti-microbial activity of some 1- substituted amino-4,6-dimethyl-2-oxo-pyridine-3-carbonitrile derivatives.

PubMed

Khidre, Rizk E; Abu-Hashem, Ameen A; El-Shazly, Mohamed

2011-10-01

A new series of 1- substituted amino-4,6-dimethyl-2-oxo-pyridine-3-carbonitrile such as hydrazide hydrazones 3a-h; ethane-1,2-diaminopyridine 6; phthalimidopyridines 8a,b; hydrazides 10a,b; urea 11a and thiourea 11b were synthesized in a good to excellent yield in step efficient process, using 1-amino-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (1) as a key intermediate. The antibacterial and antifungal activities of the synthesized compounds were evaluated. The obtained data indicated that the majority of the tested compounds exhibited both antibacterial and antifungal activities, particularly compounds 8a and 8b showed a comparable effect to a well known antibacterial and antifungal agents. Published by Elsevier Masson SAS.

Fabrication and characterization of electrospun poly(e-caprolactone) fibrous membrane with antibacterial functionality

NASA Astrophysics Data System (ADS)

Cerkez, Idris; Sezer, Ayse; Bhullar, Sukhwinder K.

2017-02-01

This research study is mainly targeted on fabrication and characterization of antibacterial poly(e-caprolactone) (PCL) based fibrous membrane containing silver chloride particles. Micro/nano fibres were produced by electrospinning and characterized with TGA, DSC, SEM and mechanical analysis. It was found that addition of silver particles slightly reduced onset of thermal degradation and increased crystallization temperature of neat PCL. Silver-loaded samples exhibited higher tensile stress and lower strain revealing that the particles behaved as reinforcing agent. Moreover, addition of silver chloride resulted in beaded surface texture and formation of finer fibres as opposed to the neat. Antibacterial properties were tested against Gram-negative and Gram-positive bacteria and remarkable biocidal functionalities were obtained with about six logs reduction of Staphylococcus aureus and Escherichia coli O157:H7.

Solvothermal synthesis of Au@Fe3O4 nanoparticles for antibacterial applications

NASA Astrophysics Data System (ADS)

Kelgenbaeva, Zhazgul; Abdullaeva, Zhypargul; Murzubraimov, Bektemir

2018-04-01

We present Au@Fe3O4 nanoparticles obtained from Fe nanoparticles and HAuCl4 using a simple solvothermal method. Trisodium citrate (C6H5Na3O7*2H2O) served as a reducing agent for Au. X-ray diffraction analysis, electronic microscopes and energy-dispersive X-ray spectroscopy revealed cubic structure, elemental composition (Au, Fe and O) and spherical shape of nanoparticles. Antibacterial activity of the sample was tested against E. coli bacteria and obtained results were discussed.

Carbon nanotubes as anti-bacterial agents.

PubMed

Mocan, Teodora; Matea, Cristian T; Pop, Teodora; Mosteanu, Ofelia; Buzoianu, Anca Dana; Suciu, Soimita; Puia, Cosmin; Zdrehus, Claudiu; Iancu, Cornel; Mocan, Lucian

2017-10-01

Multidrug-resistant bacterial infections that have evolved via natural selection have increased alarmingly at a global level. Thus, there is a strong need for the development of novel antibiotics for the treatment of these infections. Functionalized carbon nanotubes through their unique properties hold great promise in the fight against multidrug-resistant bacterial infections. This new family of nanovectors for therapeutic delivery proved to be innovative and efficient for the transport and cellular translocation of therapeutic molecules. The current review examines the latest progress in the antibacterial activity of carbon nanotubes and their composites.

Synthesis and structure-activity relationship of dicationic diaryl ethers as novel potent anti-MRSA and anti-VRE agents.

PubMed

Hu, Laixing; Kully, Maureen L; Boykin, David W; Abood, Norman

2009-08-15

A series of dicationic diaryl ethers have been synthesized and evaluated for in vitro antibacterial activities, including drug resistant bacterial strains. Most of these compounds have shown potent antibacterial activities. Several compounds, such as piperidinyl and thiomorpholinyl compounds 9e and 9l, improved the antimicrobial selectivity and kept potent anti-MRSA and anti-VRE activity. The most potent bis-indole diphenyl ether 19 exhibited anti-MRSA MIC value of 0.06 microg/mL and enhanced antimicrobial selectivity.

Doxycycline Enhances Survival and Self-Renewal of Human Pluripotent Stem Cells

PubMed Central

Chang, Mi-Yoon; Rhee, Yong-Hee; Yi, Sang-Hoon; Lee, Su-Jae; Kim, Rae-Kwon; Kim, Hyongbum; Park, Chang-Hwan; Lee, Sang-Hun

2014-01-01

Summary We here report that doxycycline, an antibacterial agent, exerts dramatic effects on human embryonic stem and induced pluripotent stem cells (hESC/iPSCs) survival and self-renewal. The survival-promoting effect was also manifest in cultures of neural stem cells (NSCs) derived from hESC/iPSCs. These doxycycline effects are not associated with its antibacterial action, but mediated by direct activation of a PI3K-AKT intracellular signal. These findings indicate doxycycline as a useful supplement for stem cell cultures, facilitating their growth and maintenance. PMID:25254347

Microbiological etiology and susceptibility of bacterial conjunctivitis isolates from clinical trials with ophthalmic, twice-daily besifloxacin.

PubMed

Haas, Wolfgang; Gearinger, Lynne S; Hesje, Christine K; Sanfilippo, Christine M; Morris, Timothy W

2012-05-01

Bacterial conjunctivitis is a contagious infection of the surface of the eye usually treated empirically with topical antibiotics. Since the etiologic agent is rarely identified, it is important to monitor which bacteria cause conjunctivitis and determine their antibacterial resistance profiles. A total of 496 bacterial samples were isolated during a randomized, double-masked, vehicle-controlled, parallel-group study conducted in the United States with besifloxacin ophthalmic suspension 0.6% dosed twice daily. Species were determined by standard biochemical and/or molecular identification methods. Minimum inhibitory concentrations were determined according to Clinical and Laboratory Standards Institute standards. The most prevalent species was Haemophilus influenzae, followed by Staphylococcus epidermidis, Staphylococcus aureus, the Streptococcus mitis group, and Streptococcus pneumoniae. One species identified in this study, which was not previously noted as a common cause of bacterial conjunctivitis, was Dolosigranulum pigrum. Ampicillin resistance was common among H. influenzae isolates, while macrolide resistance was high among S. pneumoniae, S. epidermidis, and S. aureus. The latter two species also included a number of isolates resistant to methicillin and ciprofloxacin. Antibiotic resistance among isolates remains a concern and the appearance of an emerging ocular pathogen, D. pigrum, suggests the need for continued observation. The topical ophthalmic fluoroquinolones continue to provide a good balance of low to moderate (i.e., manageable) levels of resistance plus broad-spectrum coverage for empiric treatment of ocular infections.

Enhanced water-solubility and antibacterial activity of novel chitosan derivatives modified with quaternary phosphonium salt.

PubMed

Zhu, Dan; Cheng, Honghao; Li, Jianna; Zhang, Wenwen; Shen, Yuanyuan; Chen, Shaojun; Ge, Zaochuan; Chen, Shiguo

2016-04-01

Chitosan (CS) has been widely recognized as an important biomaterial due to its good antimicrobial activity, biocompatibility and biodegradability. However, CS is insoluble in water in neutral and alkaline aqueous solution due to the linear aggregation of chain molecules and the formation of crystallinity. This is one of the key factors that limit its practical applications. Therefore, improving the solubility of CS in neutral and alkaline aqueous solution is a primary research direction for biomedical applications. In this paper, a reactive antibacterial compound (4-(2,5-Dioxo-pyrrolidin-1-yloxycarbonyl)-benzyl)-triphenyl-phosphonium bromide (NHS-QPS) was synthesized for chemical modification of CS, and a series of novel polymeric antimicrobial agents, N-quaternary phosphonium chitosan derivatives (N-QPCSxy, x=1-2,y=1-4) were obtained. The water solubilities and antibacterial activities of N-QPCSxy against Escherichia coli and Staphylococcus aureus were evaluated compare to CS. The water solubility of N-QPCSxy was all better than that of CS at neutral pH aqueous solution, particularly, N-QPCS14 can be soluble in water over the pH range of 3 to 12. The antibacterial activities of CS derivatives were improved by introducing quaternary phosphonium salt, and antibacterial activity of N-QPCSxy increases with degree of substitution. Overall, N-QPCS14 represents a novel antibacterial polymer material with good antibacterial activity, waters solubility and low cytotoxicity. Copyright © 2015 Elsevier B.V. All rights reserved.

Shape effect on the antibacterial activity of silver nanoparticles synthesized via a microwave-assisted method.

PubMed

Hong, Xuesen; Wen, Junjie; Xiong, Xuhua; Hu, Yongyou

2016-03-01

Silver nanoparticles (AgNPs) are used as sustained-release bactericidal agents for water treatment. Among the physicochemical characteristics of AgNPs, shape is an important parameter relevant to the antibacterial activity. Three typically shaped AgNPs, nanocubes, nanospheres, and nanowires, were prepared via a microwave-assisted method and characterized by TEM, UV-vis, and XRD. The antibacterial activity of AgNPs was determined by OD growth curves tests, MIC tests, and cell viability assay against Escherichia coli. The interaction between AgNPs and bacterial cells was observed by TEM. The results showed that the three differently shaped AgNPs were nanoscale, 55 ± 10 nm in edge length for nanocubes, 60 ± 15 nm in diameter for nanospheres, 60 ± 10 nm in diameter and 2-4 μm in length for nanowires. At the bacterial concentration of 10(4) CFU/mL, the MIC of nanocubes, nanospheres, and nanowires were 37.5, 75, and 100 μg/mL, respectively. Due to the worst contact with bacteria, silver nanowires exhibited the weakest antibacterial activity compared with silver nanocubes and silver nanospheres. Besides, silver nanocubes mainly covered by {100} facets showed stronger antibacterial activity than silver nanospheres covered by {111} facets. It suggests that the shape effect on the antibacterial activity of AgNPs is attributed to the specific surface areas and facets reactivity; AgNPs with larger effective contact areas and higher reactive facets exhibit stronger antibacterial activity.

Colloidal and antibacterial properties of novel triple-headed, double-tailed amphiphiles: exploring structure-activity relationships and synergistic mixtures.

PubMed

Marafino, John N; Gallagher, Tara M; Barragan, Jhosdyn; Volkers, Brandi L; LaDow, Jade E; Bonifer, Kyle; Fitzgerald, Gabriel; Floyd, Jason L; McKenna, Kristin; Minahan, Nicholas T; Walsh, Brenna; Seifert, Kyle; Caran, Kevin L

2015-07-01

Two novel series of tris-cationic, tripled-headed, double-tailed amphiphiles were synthesized and the effects of tail length and head group composition on the critical aggregation concentration (CAC), thermodynamic parameters, and minimum inhibitory concentration (MIC) against six bacterial strains were investigated. Synergistic antibacterial combinations of these amphiphiles were also identified. Amphiphiles in this study are composed of a benzene core with three benzylic ammonium bromide groups, two of which have alkyl chains, each 8-16 carbons in length. The third head group is a trimethylammonium or pyridinium. Log of critical aggregation concentration (log[CAC]) and heat of aggregation (ΔHagg) were both inversely proportional to the length of the linear hydrocarbon chains. Antibacterial activity increases with tail length until an optimal tail length of 12 carbons per chain, above which, activity decreased. The derivatives with two 12 carbon chains had the best antibacterial activity, killing all tested strains at concentrations of 1-2μM for Gram-positive and 4-16μM for Gram-negative bacteria. The identity of the third head group (trimethylammonium or pyridinium) had minimal effect on colloidal and antibacterial activity. The antibacterial activity of several binary combinations of amphiphiles from this study was higher than activity of individual amphiphiles, indicating that these combinations are synergistic. These amphiphiles show promise as novel antibacterial agents that could be used in a variety of applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations.

PubMed

Salvioni, Lucia; Galbiati, Elisabetta; Collico, Veronica; Alessio, Giulia; Avvakumova, Svetlana; Corsi, Fabio; Tortora, Paolo; Prosperi, Davide; Colombo, Miriam

2017-01-01

The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens) and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs) are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases. Water-soluble, negatively charged silver nanoparticles (AgNPs) were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet-visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs. In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells. We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared to currently available colloidal silver, suitable for cosmetic preservatives and pharmaceutical preparations administrable to humans and/or animals as needed.

Actinopyga lecanora Hydrolysates as Natural Antibacterial Agents

PubMed Central

Ghanbari, Raheleh; Ebrahimpour, Afshin; Abdul-Hamid, Azizah; Ismail, Amin; Saari, Nazamid

2012-01-01

Actinopyga lecanora, a type of sea cucumber commonly known as stone fish with relatively high protein content, was explored as raw material for bioactive peptides production. Six proteolytic enzymes, namely alcalase, papain, pepsin, trypsin, bromelain and flavourzyme were used to hydrolyze A. lecanora at different times and their respective degrees of hydrolysis (DH) were calculated. Subsequently, antibacterial activity of the A. lecanora hydrolysates, against some common pathogenic Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas sp.) were evaluated. Papain hydrolysis showed the highest DH value (89.44%), followed by alcalase hydrolysis (83.35%). Bromelain hydrolysate after one and seven hours of hydrolysis exhibited the highest antibacterial activities against Pseudomonas sp., P. aeruginosa and E. coli at 51.85%, 30.07% and 30.45%, respectively compared to the other hydrolysates. Protein hydrolysate generated by papain after 8 h hydrolysis showed maximum antibacterial activity against S. aureus at 20.19%. The potent hydrolysates were further fractionated using RP-HPLC and antibacterial activity of the collected fractions from each hydrolysate were evaluated, wherein among them only three fractions from the bromelain hydrolysates exhibited inhibitory activities against Pseudomonas sp., P. aeruginosa and E. coli at 24%, 25.5% and 27.1%, respectively and one fraction of papain hydrolysate showed antibacterial activity of 33.1% against S. aureus. The evaluation of the relationship between DH and antibacterial activities of papain and bromelain hydrolysates revealed a meaningful correlation of four and six order functions. PMID:23222684

Enrichment of enzymatically mineralized gellan gum hydrogels with phlorotannin-rich Ecklonia cava extract Seanol(®) to endow antibacterial properties and promote mineralization.

PubMed

Douglas, Timothy E L; Dokupil, Agnieszka; Reczyńska, Katarzyna; Brackman, Gilles; Krok-Borkowicz, Malgorzata; Keppler, Julia K; Božič, Mojca; Van Der Voort, Pascal; Pietryga, Krzysztof; Samal, Sangram Keshari; Balcaen, Lieve; van den Bulcke, Jan; Van Acker, Joris; Vanhaecke, Frank; Schwarz, Karin; Coenye, Tom; Pamuła, Elżbieta

2016-08-10

Hydrogels offer several advantages as biomaterials for bone regeneration, including ease of incorporation of soluble substances such as mineralization-promoting enzymes and antibacterial agents. Mineralization with calcium phosphate (CaP) increases bioactivity, while antibacterial activity reduces the risk of infection. Here, gellan gum (GG) hydrogels were enriched with alkaline phosphatase (ALP) and/or Seanol(®), a seaweed extract rich in phlorotannins (brown algae-derived polyphenols), to induce mineralization with CaP and increase antibacterial activity, respectively. The sample groups were unmineralized hydrogels, denoted as GG, GG/ALP, GG/Seanol and GG/Seanol/ALP, and hydrogels incubated in mineralization medium (0.1 M calcium glycerophosphate), denoted as GG/ALP_min, GG/Seanol_min and GG/Seanol/ALP_min. Seanol(®) enhanced mineralization with CaP and also increased compressive modulus. Seanol(®) and ALP interacted in a non-covalent manner. Release of Seanol(®) occurred in a burst phase and was impeded by ALP-mediated mineralization. Groups GG/Seanol and GG/ALP/Seanol exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus. GG/Seanol/ALP_min, but not GG/Seanol_min, retained some antibacterial activity. Eluates taken from groups GG/ALP_min, GG/Seanol_min and GG/ALP/Seanol_min displayed comparable cytotoxicity towards MG-63 osteoblast-like cells. These results suggest that enrichment of hydrogel biomaterials with phlorotannin-rich extracts is a promising strategy to increase mineralizability and antibacterial activity.

Covalent modification of a ten-residue cationic antimicrobial peptide with levofloxacin

NASA Astrophysics Data System (ADS)

Rodriguez, Carlos; Papanastasiou, Emilios; Juba, Melanie; Bishop, Barney

2014-09-01

The rampant spread of antibiotic resistant bacteria has spurred interest in alternative strategies for developing next-generation antibacterial therapies. As such, there has been growing interest in cationic antimicrobial peptides (CAMPs) and their therapeutic applications. Modification of CAMPs via conjugation to auxiliary compounds, including small molecule drugs, is a new approach to developing effective, broad-spectrum antibacterial agents with novel physicochemical properties and versatile antibacterial mechanisms. Here, we’ve explored design parameters for engineering CAMPs conjugated to small molecules with favorable physicochemical and antibacterial properties by covalently affixing a fluoroquinolone antibiotic, levofloxacin, to the ten-residue CAMP Pep-4. Relative to the unmodified Pep-4, the conjugate was found to demonstrate substantially increased antibacterial potency under high salt concentrations. Historically, it has been observed that most CAMPs lose antibacterial effectiveness in such high ionic strength environments, a fact that has presented a challenge to their development as therapeutics. Physicochemical studies revealed that P4LC was more hydrophobic than Pep-4, while mechanistic findings indicated that the conjugate was more effective at disrupting bacterial membrane integrity. Although the inherent antibacterial effect of the incorporated levofloxacin molecules did not appear to be substantially realized in this conjugate, these findings nevertheless suggest that covalent attachment of small molecule antibiotics with favorable physicochemical properties to CAMPs could be a promising strategy for enhancing peptide performance and overall therapeutic potential. These results have broader applicability to the development of future CAMP-antibiotic conjugates for potential therapeutic applications.

Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations

PubMed Central

Salvioni, Lucia; Galbiati, Elisabetta; Collico, Veronica; Alessio, Giulia; Avvakumova, Svetlana; Corsi, Fabio; Tortora, Paolo; Prosperi, Davide; Colombo, Miriam

2017-01-01

Background The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens) and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs) are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases. Methods Water-soluble, negatively charged silver nanoparticles (AgNPs) were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet–visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs. Results In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells. Conclusion We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared to currently available colloidal silver, suitable for cosmetic preservatives and pharmaceutical preparations administrable to humans and/or animals as needed. PMID:28408822

Bostrycin, a novel coupling agent for protein immobilization and prevention of biomaterial-centered infection produced by Nigrospora sp. No. 407.

PubMed

Yang, Wen-Jen; Yang, Chih-Sheng; Huang, Chen-Ji; Chen, Ko-Shao; Lin, Shuen-Fuh

2012-05-10

Bostrycin, a red antibacterial agent with tetrahydroanthraquinone structure, has been isolated from Nigrospora sp. No. 407. This study investigated the potential antibacterial and multifunctional properties of matrixes through immobilization of bostrycin on their surface for immobilization of protein and prevention of bacterial growth. Bostrycin was immobilized on nonwoven polypropylene (PP) fabric by a technique using glutaraldehyde and polyethyleneimine for the activation of the surface. Glucose oxidase immobilized on bostrycin-treated nonwoven PP fabric showed high activity. The immobilization process improved thermal stability of the enzymes. During repeated assay for 30 cycles, the enzyme activity dropped to only 70% of the initial activity. Both bostrycin-treated nonwoven PP fabric sample and subsequently immobilized glucose oxidase sample on the surface also still exhibited a bacteriostatic effect. This is the first study to show that bostrycin is a promising coupling agent for surface modification on matrix and its potential applications in protein immobilization and biomaterial-centered infection. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

Gas chromatography - Mass spectrometry analysis and antibacterial activity of Cinnamomum burmanii essential oil to Staphylococcus aureus and Escherichia coli by gaseous contact

NASA Astrophysics Data System (ADS)

Chairunnisa, Tamhid, Hady Anshory; Nugraha, Arde Toga

2017-03-01

Infectious diseases and antibiotic resistance becomes a problem that must be resolved. Plant based products are among the alternative agents examined in order to replace conventional antibiotics. Cinnamaldehyde is one of the compound in cinnamon oil that has antibacterial activity. But the other compounds in cinnamon oil has also the potential antibacterial activity. The purpose of this study to conduct GC-MS analysis of cinnamon oil and its antibacterial activity to Staphylococcus aureus and Escherichia coli by gaseous contact. Cinnamomum burmannii was distilled by water-steam distillation to obtain essential oil. Identification of compounds was analyzed by GC-MS. Antibacterial activity was observed by gaseous contact method in airtight boxes. The GC-MS analyzed showed that there are four major compounds of cinnamon oil, trans-cinnamaldehyde (56,10%), 1,8-cineole (16,53%), α-pinene (3,44%) and α -terpineol (3,05%). The Minimum Inhibitory Dose (MID) of cinnamon oil to E. coli and S. aureus was 12.5 µL/L and 6.26 µL/L respectively. Gas compounds of cinnamon oil has more effective to gram-positive bacteria than gram-negative bacteria.

Albumin reduces the antibacterial efficacy of wound antiseptics against Staphylococcus aureus.

PubMed

Kapalschinski, N; Seipp, H M; Kückelhaus, M; Harati, K K; Kolbenschlag, J J; Daigeler, A; Jacobsen, F; Lehnhardt, M; Hirsch, T

2017-04-02

The influence of proteins on the efficacy of antiseptic solutions has been rarely investigated even though exudate can contain high levels of protien. The aim of this study was to analyse the antibacterial efficacy of commonly used solutions in the presence of albumin protein. Using Staphylococcus aureus in a standardised quantitative suspension assay, the antibacterial effects of poly (1-(2-oxo-1-pyrrolidinyl) ethylene)-iodine (PVP-I) and octenidin-dihydrochloride/phenoxyethanol (OCT/PE) were analysed in the presence of 0-3% bovine serum albumin (BSA). These were compared with previous results obtained with polyhexamethylene biguanide hydrochloride (PHMB). Presence of albumin caused a significant (p<0.001) decrease in antibacterial effect in the analysed solutions. The concentrations of albumin that provoked highly significant decreases in the bacterial reduction factors of the study agents were: 0.01875 % for PVP-I, followed by 0.75 % for OCT/PE. After addition of 3 % albumin, adequate antimicrobial effects were ensured for titrations to 5 % PVP-I and 8 % OCT/PE. As we could show before, it is not possible to titrate PHMB in order to assure adequate potency. This study demonstrates that albumin induces a significant decrease of the antibacterial potency of the analysed solutions.

N-O chemistry for antibiotics: discovery of N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds as selective antibacterial agents using nitroso Diels-Alder and ene chemistry.

PubMed

Wencewicz, Timothy A; Yang, Baiyuan; Rudloff, James R; Oliver, Allen G; Miller, Marvin J

2011-10-13

The discovery, syntheses, and structure-activity relationships (SAR) of a new family of heterocyclic antibacterial compounds based on N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds are described. A structurally diverse library of ∼100 heterocyclic molecules generated from Lewis acid-mediated nucleophilic ring-opening reactions with nitroso Diels-Alder cycloadducts and nitroso ene reactions with substituted alkenes was evaluated in whole cell antibacterial assays. Compounds containing the N-alkyl-N-(pyridin-2-yl)hydroxylamine structure demonstrated selective and potent antibacterial activity against the Gram-positive bacterium Micrococcus luteus ATCC 10240 (MIC(90) = 2.0 μM or 0.41 μg/mL) and moderate activity against other Gram-positive strains including antibiotic resistant strains of Staphylococcus aureus (MRSA) and Enterococcus faecalis (VRE). A new synthetic route to the active core was developed using palladium-catalyzed Buchwald-Hartwig amination reactions of N-alkyl-O-(4-methoxybenzyl)hydroxylamines with 2-halo-pyridines that facilitated SAR studies and revealed the simplest active structural fragment. This work shows the value of using a combination of diversity-oriented synthesis (DOS) and parallel synthesis for identifying new antibacterial scaffolds.

N-O Chemistry for Antibiotics: Discovery of N-Alkyl-N-(pyridin-2-yl)hydroxylamine Scaffolds as Selective Antibacterial Agents Using Nitroso Diels-Alder and Ene Chemistry

PubMed Central

Wencewicz, Timothy A.; Yang, Baiyuan; Rudloff, James R.; Oliver, Allen G.; Miller, Marvin J.

2011-01-01

The discovery, syntheses, and structure-activity relationships (SAR) of a new family of heterocyclic antibacterial compounds based on N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds are described. A structurally diverse library of ~100 heterocyclic molecules generated from Lewis acid-mediated nucleophilic ring opening reactions with nitroso Diels-Alder cycloadducts and nitroso ene reactions with substituted alkenes was evaluated in whole cell antibacterial assays. Compounds containing the N-alkyl-N-(pyridin-2-yl)hydroxylamine structure demonstrated selective and potent antibacterial activity against the Gram-positive bacterium Micrococcus luteus ATCC 10240 (MIC90 = 2.0 μM or 0.41 μg/mL) and moderate activity against other Gram-positive strains including antibiotic resistant strains of Staphylococcus aureus (MRSA) and Enterococcus faecalis (VRE). A new synthetic route to the active core was developed using palladium-catalyzed Buchwald-Hartwig amination reactions of N-alkyl-O-(4-methoxybenzyl)hydroxylamines with 2-halo-pyridines that facilitated SAR studies and revealed the simplest active structural fragment. This work shows the value of using a combination of diversity-oriented synthesis (DOS) and parallel synthesis for identifying new antibacterial scaffolds. PMID:21859126

Antibacterial Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Cytotoxic Effect against MDA-MB-468 and MDA-MB-231 Breast Cancer Cell Lines.

PubMed

Vargas Casanova, Yerly; Rodríguez Guerra, Jorge Antonio; Umaña Pérez, Yadi Adriana; Leal Castro, Aura Lucía; Almanzar Reina, Giovanni; García Castañeda, Javier Eduardo; Rivera Monroy, Zuly Jenny

2017-09-29

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B, containing the RRWQWR motif, were designed, synthesized, purified, and characterized using RP-HPLC chromatography and MALDI-TOF mass spectrometry. The antibacterial activity of the designed peptides against E. coli (ATCC 11775 and 25922) and their cytotoxic effect against MDA-MB-468 and MDA-MB-231 breast cancer cell lines were evaluated. Dimeric and tetrameric peptides showed higher antibacterial activity in both bacteria strains than linear peptides. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strains. Furthermore, the peptides with high antibacterial activity exhibited significant cytotoxic effect against the tested breast cancer cell lines. This cytotoxic effect was fast and dependent on the peptide concentration. The tetrameric molecule containing RRWQWR motif has an optimal cytotoxic effect at a concentration of 22 µM. The evaluated dimeric and tetrameric peptides could be considered as candidates for developing new therapeutic agents against breast cancer. Polyvalence of linear sequences could be considered as a novel and versatile strategy for obtaining molecules with high anticancer activity.

Controlled release and long-term antibacterial activity of reduced graphene oxide/quaternary ammonium salt nanocomposites prepared by non-covalent modification.

PubMed

Ye, Xiaoli; Feng, Jin; Zhang, Jingxian; Yang, Xiujiang; Liao, Xiaoyan; Shi, Qingshan; Tan, Shaozao

2017-01-01

In order to control the long-term antibacterial property of quaternary ammonium salts, dodecyl dimethyl benzyl ammonium chloride (rGO-1227) and rGO-bromohexadecyl pyridine (rGO-CPB) were self-assembled on surfaces of reduced graphene oxide (rGO) via π-π interactions. The obtained rGO-1227 and rGO-CPB nanocompounds were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM).The antibacterial activities were evaluated on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both rGO-CPB and rGO-1227 reduced the cytotoxicity of the pure antimicrobial agents and presented strong antimicrobial properties. Especially, CPB could be loaded efficiently on the surface of rGO via π-π conjugate effect, which resulted in a nanocomposite presenting a long-term antibacterial capability due to the more important quantity of free π electrons compared to that of 1227. When comparing the advantages of both prepared nanocomposites, rGO-CPB displayed a better specific-targeting capability and a longer-term antibacterial property. Copyright © 2016 Elsevier B.V. All rights reserved.

Antimicrobial efficacy of oral topical agents on microorganisms associated with radiated head and neck cancer patients: an in vitro study.

PubMed

Bidra, Avinash S; Tarrand, Jeffery J; Roberts, Dianna B; Rolston, Kenneth V; Chambers, Mark S

2011-04-01

A variety of oral topical agents have been used for prevention and management of radiotherapy-induced adverse effects. The antimicrobial nature of some of the commonly used agents is unknown. The purpose of this study was to evaluate antimicrobial efficacies of various oral topical agents on common microorganisms associated with radiated head and neck cancer patients. Seven commonly used topical oral agents-0.12% chlorhexidine with alcohol, 0.12% chlorhexidine without alcohol, baking soda-salt rinse, 0.4% stannous fluoride gel, 0.63% stannous fluoride rinse, calcium phosphate mouthrinse, and acemannan hydrogel (aloe vera) rinse-were evaluated in vitro for their antimicrobial efficacies against four common microorganisms. A combination of baking soda-salt rinse and 0.4% stannous fluoride gel was evaluated as the eighth agent. The microorganisms used were Staphylococcus aureus, group B Streptococcus, Escherichia coli, and Candida albicans. An ELISA reader was used to measure the turbidity of microbial culture wells and optical density (OD) values for each of the 960 wells recorded. Mean OD values were rank ordered based on their turbidity. One-way ANOVA with Tukey HSD post hoc analysis was used to study differences in OD values (P < .05). Mean OD values classified for topical agents from lowest to highest were chlorhexidine with alcohol, chlorhexidine without alcohol, baking soda- salt, calcium phosphate rinse, and the combination of baking soda-salt and stannous fluoride gel. Mean OD values classified for microorganisms from lowest to highest were Escherichia coli, Staphylococcus aureus, group B Streptococcus, and Candida albicans. A significant difference among the antimicrobial efficacies of topical agents was evident for each of four microorganisms (P < .05). There was also a significant difference among the antimicrobial efficacies of the same topical agent on the four microorganisms tested (P < .05).

Determination of antibacterial activity and minimum inhibitory concentration of larval extract of fly via resazurin-based turbidometric assay.

PubMed

Teh, Chien Huey; Nazni, Wasi Ahmad; Nurulhusna, Ab Hamid; Norazah, Ahmad; Lee, Han Lim

2017-02-16

Antimicrobial resistance is currently a major global issue. As the rate of emergence of antimicrobial resistance has superseded the rate of discovery and introduction of new effective drugs, the medical arsenal now is experiencing shortage of effective drugs to combat diseases, particularly against diseases caused by the dreadful multidrug-resistant strains, such as the methicillin-resistant Staphylococcus aureus (MRSA). The ability of fly larvae to thrive in septic habitats has prompted us to determine the antibacterial activity and minimum inhibitory concentrations (MICs) of larval extract of flies, namely Lucilia cuprina, Sarcophaga peregrina and Musca domestica against 4 pathogenic bacteria [Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa and Escherichia coli] via a simple and sensitive antibacterial assay, resazurin-based turbidometric (TB) assay as well as to demonstrate the preliminary chemical profile of larval extracts using gas chromatography-mass spectrophotometry (GC-MS). The resazurin-based TB assay demonstrated that the L. cuprina larval extract was inhibitory against all tested bacteria, whilst the larval extract of S. peregrina and M. domestica were only inhibitory against the MRSA, with a MIC of 100 mg ml -1 . Subsequent sub-culture of aliquots revealed that the larval extract of L. cuprina was bactericidal against MRSA whilst the larval extracts of S. peregrina and M. domestica were bacteriostatic against MRSA. The GC-MS analysis had quantitatively identified 20 organic compounds (fatty acids or their derivatives, aromatic acid esters, glycosides and phenol) from the larval extract of L. cuprina; and 5 fatty acid derivatives with known antimicrobial activities from S. peregrina and M. domestica. The resazurin-based turbidometric assay is a simple, reliable and feasible screening assay which evidently demonstrated the antibacterial activity of all fly larval extracts, primarily against the MRSA. The larval extract of L. cuprina exerted a broad spectrum antibacterial activity against all tested bacteria. The present study revealed probable development and use of novel and effective natural disinfectant(s) and antibacterial agent(s) from flies and efforts to screen more fly species for antibacterial activity using resazurin-based TB assay should be undertaken for initial screening for subsequent discovery and isolation of potential novel antimicrobial substances, particularly against the multi-drug resistant strains.

Insights into the Mechanism of Action of Bactericidal Lipophosphonoxins.

PubMed

Panova, Natalya; Zborníková, Eva; Šimák, Ondřej; Pohl, Radek; Kolář, Milan; Bogdanová, Kateřina; Večeřová, Renata; Seydlová, Gabriela; Fišer, Radovan; Hadravová, Romana; Šanderová, Hana; Vítovská, Dragana; Šiková, Michaela; Látal, Tomáš; Lovecká, Petra; Barvík, Ivan; Krásný, Libor; Rejman, Dominik

2015-01-01

The advantages offered by established antibiotics in the treatment of infectious diseases are endangered due to the increase in the number of antibiotic-resistant bacterial strains. This leads to a need for new antibacterial compounds. Recently, we discovered a series of compounds termed lipophosphonoxins (LPPOs) that exhibit selective cytotoxicity towards Gram-positive bacteria that include pathogens and resistant strains. For further development of these compounds, it was necessary to identify the mechanism of their action and characterize their interaction with eukaryotic cells/organisms in more detail. Here, we show that at their bactericidal concentrations LPPOs localize to the plasmatic membrane in bacteria but not in eukaryotes. In an in vitro system we demonstrate that LPPOs create pores in the membrane. This provides an explanation of their action in vivo where they cause serious damage of the cellular membrane, efflux of the cytosol, and cell disintegration. Further, we show that (i) LPPOs are not genotoxic as determined by the Ames test, (ii) do not cross a monolayer of Caco-2 cells, suggesting they are unable of transepithelial transport, (iii) are well tolerated by living mice when administered orally but not peritoneally, and (iv) are stable at low pH, indicating they could survive the acidic environment in the stomach. Finally, using one of the most potent LPPOs, we attempted and failed to select resistant strains against this compound while we were able to readily select resistant strains against a known antibiotic, rifampicin. In summary, LPPOs represent a new class of compounds with a potential for development as antibacterial agents for topical applications and perhaps also for treatment of gastrointestinal infections.

Green synthesis of highly concentrated aqueous colloidal solutions of large starch-stabilised silver nanoplatelets.

PubMed

Cheng, Fei; Betts, Jonathan W; Kelly, Stephen M; Hector, Andrew L

2015-01-01

A simple, environmentally friendly and cost-effective method has been developed to prepare a range of aqueous silver colloidal solutions, using ascorbic acid as a reducing agent, water-soluble starch as a combined crystallising, stabilising and solubilising agent, and water as the solvent. The diameter of silver nanoplatelets increases with higher concentrations of AgNO3 and starch. The silver nanoparticles are also more uniform in shape the greater the diameter of the nanoparticles. Colloidal solutions with a very high concentration of large, flat, hexagonal silver nanoplatelets (~230 nm in breadth) have been used to deposit and fix an antibacterial coating of these large starch-stabilised silver nanoplates on commercial cotton fibres, using a simple dip-coating process using water as the solvent, in order to study the dependence of the antibacterial properties of these nanoplatelets on their size. Copyright © 2014 Elsevier B.V. All rights reserved.

Substituted 3-((Z)-2-(4-nitrophenyl)-2-(1H-tetrazol-5-yl) vinyl)-4H-chromen-4-ones as novel anti-MRSA agents: synthesis, SAR, and in-vitro assessment.

PubMed

Diwakar, Santosh D; Bhagwat, Sachin S; Shingare, Murlidhar S; Gill, Charansing H

2008-08-15

In search for a new antibacterial agent with improved antimicrobial spectrum and potency, we designed and synthesized a series of novel 3-((Z)-2-(4-nitrophenyl)-2-(1H-tetrazol-5-yl) vinyl)-4H-chromen-4-ones 7a-h by convergent synthesis approach. All the synthesized compounds were assayed for their in-vitro antibacterial activities against gram-negative and gram-positive bacteria. The preliminary structure-activity relationship, to elucidate the essential structure requirements for the antimicrobial activity that results into anti-MRSA (methicillin-resistant S. aureus) potential, has been described. Amongst the synthesized compounds 7d, 7e, 7f and 7h were found to possess activity against methicillin-resistant S. aureus in addition to the activity against other bacterial strains such as E. faecalis, S. pneumoniae, and E. coli.

[The antibacterial immunity of people under dynamic observation in an altered radiation situation].

PubMed

Bidnenko, S I; Nazarchuk, L V; Fedorovskaia, E A; Liutko, O B; Open'ko, L B

1992-01-01

The comparative study of the isolation rate, level, antigenic and class specificity of serum antibodies to the causative agents of purulent septic infections (Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis) and acute enteric infections in healthy adults with different ABO blood groups before (836 persons) and after (1,429 persons) the catastrophe at the Chernobyl nuclear power station was made. The study revealed the fact that the genesis of antibodies directed against different microorganisms can be stimulated without additional antigenic challenge in the form of disease or immunization, which was definitely indicative of the influence of small radiation doses in Kiev on the humoral immunity of the population. The multifactor character of the dependence of antibacterial antibody formation under altered radiation conditions on the specific features of the infective agent and the intensity of its circulation among the population, individual immune responsiveness of the body and concrete radiation conditions was established.

Synthesis and antibacterial activity of Schiff bases and amines derived from alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates.

PubMed

Goszczyńska, Agata; Kwiecień, Halina; Fijałkowski, Karol

A series of novel Schiff bases and secondary amines were obtained in good yields, as a result of the reductive amination of alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates with both aniline and 4-methoxyaniline under established mild reaction conditions. Sodium triacetoxyborohydride as well as hydrogen in the presence of palladium on carbon were used as efficient reducing agents of the Schiff bases, in both direct and stepwise reductive amination processes. The Schiff bases, amines, and amine hydrochlorides were designed as potential antibacterial agents, and structure-activity relationship could be established following in vitro assays against Gram-positive and Gram-negative bacteria. The minimal inhibitory concentration and zone of inhibition were also determined. In these tests, some of Schiff bases and secondary amine hydrochlorides showed moderate-to-good activity against Gram-positive bacteria, including S. aureus , M. luteus , and S. mutans .

Enhanced biocompatibility of ZnS:Mn quantum dots encapsulated with Aloe vera extract for therapeutic applications

NASA Astrophysics Data System (ADS)

Anilkumar, M.; Bindu, K. R.; Sneha Saj, A.; Anila, E. I.

2016-08-01

Toxicity of nanoparticles remains to be a major issue in their application to the biomedical field. Aloe vera (AV) is one of the most widely exploited medicinal plants that have a multitude of amazing properties in the field of medicine. Methanol extract of Aloe vera can be used as a novel stabilising agent for quantum dots to reduce toxicity. We report the synthesis, structural characterization, antibacterial activity and cytotoxicity studies of ZnS:Mn quantum dots synthesized by the colloidal precipitation method, using methanol extract of Aloe vera (AVME) as the capping agent. The ZnS:Mn quantum dots capped with AVME exhibit superior performances in biocompatibility and antibacterial activity compared with ZnS:Mn quantum dots without encapsulation. Project supported by the Science and Engineering Research Board (SERB), Department of Science and Technology (DST), Government of India.

Hydrogen peroxide-dependent antibacterial action of Melilotus albus honey.

PubMed

Sowa, P; Grabek-Lejko, D; Wesołowska, M; Swacha, S; Dżugan, M

2017-07-01

Honey originating from different floral sources exhibits the broad spectrum of antibacterial activity as a result of the presence of hydrogen peroxide as well as nonperoxide bioactive compounds. The mechanisms of antibacterial activity of Polish melilot honey were investigated for the first time. Polish melilot honey samples (Melilotus albus biennial = 3 and annual = 5, Melilotus officinalis = 1) were collected directly from beekeepers and analysed for pollen profile, basic physicochemical parameters, antioxidant capacity, radical scavenging activity, total phenolic contents as well as antibacterial properties against pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Salmonella spp. The physicochemical properties of melilot honey were specific for light-coloured unifloral honey samples and were not dependent on its botanical and geographical origin (P > 0·05). All tested honey samples exhibited inhibitory activity (above 90%) against Gram-positive bacteria at the concentration of 12·5-25%. Above 30-50% of antibacterial activity of melilot honey was connected with glucose oxidase enzyme action and was destroyed in the presence of catalase. Hydrogen peroxide-dependent antibacterial activity of honey was inversely correlated with its radical scavenging activity (r = -0·67) and phenolic compounds (r = -0·61). Antibacterial action of melilot honey depends not only on hydrogen peroxide produced by glucose oxidase, but also on other nonperoxide bioactive components of honey. Melilot honey is used in traditional medicine as an anticoagulant agent due to the possibility of the presence of the coumarin compounds which are specific for Melilotus plant. Melilotus albus is rarely used to produce honey, and antibacterial properties of this variety of honey had not been studied yet. Nine samples of melilot honey produced in different regions of Poland were analysed according to their antibacterial activity which was correlated with physiochemical parameters and antioxidant activity. It was shown that antibacterial activity of melilot honey is created by hydrogen peroxide and other bioactive compounds. © 2017 The Society for Applied Microbiology.

Isojacareubin from the Chinese Herb Hypericum japonicum: Potent Antibacterial and Synergistic Effects on Clinical Methicillin-Resistant Staphylococcus aureus (MRSA)

PubMed Central

Zuo, Guo-Ying; An, Jing; Han, Jun; Zhang, Yun-Ling; Wang, Gen-Chun; Hao, Xiao-Yan; Bian, Zhong-Qi

2012-01-01

Through bioassay-guided fractionation of the extracts from the aerial parts of the Chinese herb Hypericum japonicum Thunb. Murray, Isojacareubin (ISJ) was characterized as a potent antibacterial compound against the clinical methicillin-resistant Staphylococcus aureus (MRSA). The broth microdilution assay was used to determine the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of ISJ alone. The results showed that its MICs/MBCs ranged from 4/16 to 16/64 μg/mL, with the concentrations required to inhibit or kill 50% of the strains (MIC50/MBC50) at 8/16 μg/mL. Synergistic evaluations of this compound with four conventional antibacterial agents representing different types were performed by the chequerboard and time-kill tests. The chequerboard method showed significant synergy effects when ISJ was combined with Ceftazidime (CAZ), Levofloxacin (LEV) and Ampicillin (AMP), with the values of 50% of the fractional inhibitory concentration indices (FICI50) at 0.25, 0.37 and 0.37, respectively. Combined bactericidal activities were also observed in the time-kill dynamic assay. The results showed the ability of ISJ to reduce MRSA viable counts by log10CFU/mL at 24 h of incubation at a concentration of 1 × MIC were 1.5 (LEV, additivity), 0.92 (CAZ, indifference) and 0.82 (AMP, indifference), respectively. These in vitro anti-MRSA activities of ISJ alone and its synergy with conventional antibacterial agents demonstrated that ISJ enhanced their efficacy, which is of potential use for single and combinatory therapy of patients infected with MRSA. PMID:22942699

Antibacterial Effects of Glycyrrhetinic Acid and Its Derivatives on Staphylococcus aureus

PubMed Central

Oyama, Kentaro; Kawada-Matsuo, Miki; Oogai, Yuichi; Hayashi, Tetsuya; Nakamura, Norifumi; Komatsuzawa, Hitoshi

2016-01-01

Staphylococcus aureus is a major pathogen in humans and causes serious problems due to antibiotic resistance. We investigated the antimicrobial effect of glycyrrhetinic acid (GRA) and its derivatives against 50 clinical S. aureus strains, including 18 methicillin-resistant strains. The minimum inhibitory concentrations (MICs) of GRA, dipotassium glycyrrhizate, disodium succinoyl glycyrrhetinate (GR-SU), stearyl glycyrrhetinate and glycyrrhetinyl stearate were evaluated against various S. aureus strains. Additionally, we investigated the bactericidal effects of GRA and GR-SU against two specific S. aureus strains. DNA microarray analysis was also performed to clarify the mechanism underlying the antibacterial activity of GR-SU. We detected the antimicrobial activities of five agents against S. aureus strains. GRA and GR-SU showed strong antibacterial activities compared to the other three agents tested. At a higher concentration (above 2x MIC), GRA and GR-SU showed bactericidal activity, whereas at a concentration of 1x MIC, they showed a bacteriostatic effect. Additionally, GRA and GR-SU exhibited a synergistic effect with gentamicin. The expression of a large number of genes (including transporters) and metabolic factors (carbohydrates and amino acids) was altered by the addition of GR-SU, suggesting that the inhibition of these metabolic processes may influence the degree of the requirement for carbohydrates or amino acids. In fact, the requirement for carbohydrates or amino acids was increased in the presence of either GRA or GR-SU. GRA and GR-SU exhibited strong antibacterial activity against several S. aureus strains, including MRSA. This activity may be partly due to the inhibition of several pathways involved in carbohydrate and amino acid metabolism. PMID:27820854

Biogenic synthesis of silver nanoparticles using guava ( Psidium guajava) leaf extract and its antibacterial activity against Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Bose, Debadin; Chatterjee, Someswar

2016-08-01

Among the various inorganic nanoparticles, silver nanoparticles have received substantial attention in the field of antimicrobial research. For safe and biocompatible use of silver nanoparticles in antimicrobial research, the different biogenic routes are developed to synthesize silver nanoparticles that do not use toxic chemicals. Among those, to synthesize silver nanoparticles, the use of plant part extract becomes an emerging field because plant part acts as reducing as well as capping agent. For large-scale production of antibacterial silver nanoparticles using plant part, the synthesis route should be very simple, rapid, cost-effective and environment friendly based on easy availability and non-toxic nature of plant, stability and antibacterial potential of biosynthesized nanoparticles. In the present study, we report a very simple, rapid, cost-effective and environment friendly route for green synthesis of silver nanoparticles using guava ( Psidium guajava) leaf extract as reducing as well as capping agent. This plant has been opted for the present study for its known medicinal properties, and it is easily available in all seasons and everywhere. The biosynthesized silver nanoparticles are characterized by UV-Vis and TEM analysis. The average particle size is 40 nm in the range of 10-90 nm. The antibacterial activity of these nanoparticles against Pseudomonas aeruginosa MTCC 741 has been measured by disc diffusion method, agar cup assay and serial dilution turbidity measurement assay. The results show that green synthesized silver nanoparticles, using guava ( Psidium guajava) leaf extract, have a potential to inhibit the growth of bacteria.

Globularia alypum methanolic extract improves burn wound healing process and inflammation in rats and possesses antibacterial and antioxidant activities.

PubMed

Ghlissi, Zohra; Kallel, Rim; Sila, Assaad; Harrabi, Bahira; Atheymen, Rim; Zeghal, Khaled; Bougatef, Ali; Sahnoun, Zouheir

2016-12-01

Burns are known as one of the most common and destructive forms of injury with a vast spectrum of consequences. Despite the discovery of various antibacterial and antiseptic agents, burn wound healing still has remained a challenge to modern medicine. Plants have been considered as potential agents for prevention and treatment of disorders in recent years. Globularia alypum L. (GA) is widely used in folk medicine against skin diseases and abscesses, however there is no scientific evidence justifying its use. This study aimed to evaluate the wound healing and anti-inflammatory effect, the antibacterial and antioxidant activities, as well as the chemical compositions of GA methanolic extract (GAME). Chemical compounds of GAME were examined by GC-MS. Wound healing effect was assessed by second-degree burn wounds in rats, anti-inflammatory activity was studied by carrageenan-induced rat paw edema, antioxidant activity was estimated by the DPPH, reducing power and β-carotene tests and antimicrobial activity was tested against 6 bacteria. A total of 17 compounds were identified. GAME-treated rats showed an improvement in healing process and carrageenan-induced hind paws edema as assessed by histological and biochemical investigations, compared to the control. A significant antioxidant and antibacterial activities were also observed in GAME-treated rats. GAME revealed a burn wound healing activity probably due to the anti-inflammatory, antimicrobial and antioxidant activities of its phytochemical contents. Thus, this study confirms its traditional use, however further more precise studies are needed for future clinical application. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

[Acne therapy with topical benzoyl peroxide, antibiotics and azelaic acid].

PubMed

Worret, Wolf-Ingo; Fluhr, Joachim W

2006-04-01

Benzoyl peroxide (BPO) was introduced in the treatment of acne in 1934. Despite the fact that only few randomized trials have been published, BPO is considered the standard in topical acne treatment. Anaerobic bacteria are reduced by oxidative mechanisms and the induction of resistant strains is reduced. Topical formulations are available at concentrations of 2.5, 5, 10 and 20 %. The effect is dose-dependent, but the irritation increases with higher concentrations. Usually 5 % BPO is sufficient to control acne grade I-II. Due to its strong oxidative potential, patients should be advised that BPO may bleach colored and dark clothing, bedding and even hair. BPO is safe for use in pregnant and lactating females because it is degraded to benzoic acid. It is a cost-effective treatment for acne grade I-II. Patients with papulopustular acne grade I-II, particularly with marked inflammation, show satisfactory improvement with topical antibiotic treatment. The following compounds are available and effective: erythromycin, clindamycin and tetracycline (the latter being less frequently used). A review in 1990 suggested that topical tetracycline was ineffective in the treatment of acne. Along with eliminating Propionibacterium acnes, the main mechanism of topical antibiotics is their antiinflammatory effect. All three penetrate the epidermal barrier well and are similarly efficacious. Randomized trials have shown that in concentrations of 2-4 %, their effects are comparable to oral tetracycline and minocycline. Combination therapy with retinoids or benzoyl peroxide (BPO) increases efficacy. Retinoids increase penetration and reduce comedones, while topical antibiotics primarily address inflammation. One side effect of topical antibacterial treatment is an increase in drug-resistant resident skin flora with gram-negative microorganisms prevailing, which can lead to gram-negative folliculitis. All three antibiotics fluoresce under black light which may produce interesting effects in a discotheque. There are two reports of topical clindamycin causing pseudomembranous colitis after long-term and widespread usage. Azelaic acid has a predominant antibacterial action, although it is not considered as an antibiotic in the classical sense. Furthermore, it possesses a modest comedolytic effect. Burning upon application is common. Since azelaic acid is naturally present, systemic side effects are not likely to occur, making it safe for acne treatment during pregnancy and lactation.

An environmentally benign dual action antimicrobial: quaternized chitosan/sodium alga acid multilayer films and silver nanoparticles decorated on magnetic nanoparticles.

PubMed

Jin, Feng; Xiang, Qian; Chen, Xiaoqin; Peng, Xuefeng; Xing, Xiaodong

2016-10-01

There is an urgent need to develop a puissant and environmentally benign antibacterial composite that act via multiple mechanisms to make response to the potentially daunting complexity of the microbial population and microbial antibiotic resistance. In this work, a facile and green approach, layer-by-layer self-assembly technology was applied to assemble polycation quaternized chitosan (QAC) and polyanion sodium alga acid onto magnetic nanoparticles (MNPs). Then silver nanoparticles (AgNPs) with stable and narrow-sized distribution in the range of 25-35 nm were immobilized on the surface of MNPs with L-ascorbic acid as reducing agent and organic multilayers as stabilizer. Through above modification on MNPs, we expected to achieve a green dual antibacterial and recyclable composite via the combined antibacterial action of QAC and AgNPs. Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, zeta potentials, and dynamic light scattering were employed to confirm the success of the surface functionalization. Silver ion release process was detected by inductively coupled plasma mass spectrometry. Furthermore, the antibacterial properties of the biomaterials against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were studied. The modified MNPs exhibited rapid, efficient, and long-lasting biocidal abilities against E. coli and S. aureus. The magnetic antibacterial composite still showed excellent antibacterial efficiency during five exposure/collection/recycle procedures.

Chemical composition and antibacterial activity of the essential oil and the gum of Pistacia lentiscus Var. chia.

PubMed

Koutsoudaki, Christina; Krsek, Martin; Rodger, Alison

2005-10-05

The essential oil and gum of Pistacia lentiscus var. chia, commonly known as the mastic tree, are natural antimicrobial agents that have found extensive uses in medicine in recent years. In this work, the chemical composition of mastic oil and gum was studied by GC-MS, and the majority of their components was identified. alpha-Pinene, beta-myrcene, beta-pinene, limonene, and beta-caryophyllene were found to be the major components. The antibacterial activity of 12 components of mastic oil and the oil itself was evaluated using the disk diffusion method. Furthermore, attempts were made to separate the essential oil into different fractions in order to have a better picture of the components responsible for its antibacterial activity. Several trace components that appear to contribute significantly to the antibacterial activity of mastic oil have been identified: verbenone, alpha-terpineol, and linalool. The sensitivity to these compounds was different for different bacteria tested (Escherichia coli, Staphylococcus aureus, and Bacillus subtilis), which suggests that the antibacterial efficacy of mastic oil is due to a number of its components working synergistically. The establishment of a correlation between the antibacterial activity of mastic oil and its components was the main purpose of this research. Mastic gum was also examined, but it proved to be more difficult to handle compared to the essential oil.

Interdigital athlete's foot: new concepts in pathogenesis.

PubMed

Leyden, J J; Kligman, A M

1977-06-01

In our view, interdigital athlete's foot usually begins with invasion of the horny layer by dermatophytes. Because of hot weather, sweating, exercise, or tight shoes, enough moisture accumulates to stimulate an overgrowth of bacteria. Large numbers of normally resident aerobic diphtheroids cause the common wet, macerated type of athlete's foot, while an overgrowth of Gram-negative organisms, such as Pseudomonas and Proteus, is responsible for the more serious cases. The dry, scaly type (dermatophytosis simplex) often alternates with the wet, macerated type (dermatophytosis complex). Flare-ups are common in summer and can be experimentally induced by occlusion of fungus-infected feet. Suppression of bacteria is essential in treating symptomatic athlete's foot. This can be accomplished by exposing the feet to air (eg, wearing sandals) to enhance evaporation of water and prevent the accumulation of excess moisture that stimulates bacterial overgrowth. Topical antibiotics are another approach, with the ideal perhaps being an agent with both broad-spectrum antibacterial and antifungal activity. The newer imidazoles are broad-spectrum compounds but have limited activity against Gram-negative organisms. Our agent of choice, aluminum chloride, combines broad-spectrum antimicrobial activity with chemical drying, a two-pronged attack. We view drying as the decisive element. We doubt that any local treatment can permanently eradicate athlete's foot. Potent antifungal agents can virtually exterminate interdigital dermatophytes, but the inevitable presence of infection in the nails or on the soles assures reinfection. In shoe-wearing populations living in temperate climates, interdigital athlete's foot is mainly a seasonal disease. The various therapies discussed provide a variety of approaches to prevent or ameliorate hot-weather exacerbations.

Topical antifungal agents: an update.

PubMed

Diehl, K B

1996-10-01

So many topical antifungal agents have been introduced that it has become very difficult to select the proper agent for a given infection. Nonspecific agents have been available for many years, and they are still effective in many situations. These agents include Whitfield's ointment, Castellani paint, gentian violet, potassium permanganate, undecylenic acid and selenium sulfide. Specific antifungal agents include, among others, the polyenes (nystatin, amphotericin B), the imidazoles (metronidazole, clotrimazole) and the allylamines (terbinafine, naftifine). Although the choice of an antifungal agent should be based on an accurate diagnosis, many clinicians believe that topical miconazole is a relatively effective agent for the treatment of most mycotic infections. Terbinafine and other newer drugs have primary fungicidal effects. Compared with older antifungal agents, these newer drugs can be used in lower concentrations and shorter therapeutic courses. Studies are needed to evaluate the clinical efficacies and cost advantages of both newer and traditional agents.

A novel prophage lysin Ply5218 with extended lytic activity and stability against Streptococcus suis infection.

PubMed

Zhang, Hang; Zhang, Chuanpeng; Wang, Hengan; Yan, Ya Xian; Sun, Jianhe

2016-09-01

Streptococcus suis (S. suis) is an emerging zoonotic agent that exhibits high level resistance to classic antibiotics and a heavy burden in the swine industry. Therefore alternative antibacterial agents need to be developed. A novel endolysin derived from the S. suis temperate phage phi5218, termed Ply5218, was identified. The minimum inhibitory concentration (MIC) of Ply5218 was 2.5 μg ml(-1) against S. suis strain HA9801, an activity many times greater than the lysins reported previously (MIC of LY7917 and Ply30 against HA9801 were 80 and 64 μg ml(-1), respectively). Ply5218 at 10 μg ml(-1) in vitro exerted broad antibacterial activities against S. suis strains with OD600 ratios decreased from 1 to <0.2 within 1 h. Moreover, Ply5218 showed favorable thermal stability. It was stable at 50°C >30 min, 4°C >30 days, -80°C >7 months, and >60% of the enzyme activity remained after 5 min pre-incubation at 70°C. In vivo, a 0.2 mg dose of Ply5218 protected 90% (9/10) of mice after infection with S. suis HA9801. Finally, Ply5218 maintained high antibacterial activity in some bio-matrices, such as culture media and milk. The data indicate that Ply5218 has all the characteristics to be an effective therapeutic agent against multiple S. suis infections. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Conservation of the 2-keto-3-deoxymanno-octulosonic acid (Kdo) biosynthesis pathway between plants and bacteria.

PubMed

Smyth, Kevin M; Marchant, Alan

2013-10-18

The increasing prevalence of multi-drug resistant bacteria is driving efforts in the development of new antibacterial agents. This includes a resurgence of interest in the Gram-negative bacteria lipopolysaccharide (LPS) biosynthesis enzymes as drug targets. The six carbon acidic sugar 2-keto-3-deoxymanno-octulosonic acid (Kdo) is a component of the lipid A moiety of the LPS in Gram-negative bacteria. In most cases the lipid A substituted by Kdo is the minimum requirement for cell growth, thus presenting the possibility of targeting either the synthesis or incorporation of Kdo for the development of antibacterial agents. Indeed, potent in vitro inhibitors of Kdo biosynthesis enzymes have been reported but have so far failed to show sufficient in vivo action against Gram-negative bacteria. As part of an effort to design more potent antibacterial agents targeting Kdo biosynthesis, the crystal structures of the key Kdo biosynthesis enzymes from Escherichia coli have been solved and their structure based mechanisms characterized. In eukaryotes, Kdo is found as a component of the pectic polysaccharide rhamnogalacturonan II in the plant primary cell wall. Interestingly, despite incorporating Kdo into very different macromolecules the Kdo biosynthesis and activation pathway is almost completely conserved between plants and bacteria. This raises the possibility for plant research to exploit the increasingly detailed knowledge and resources being generated by the microbiology community. Likewise, insights into Kdo biosynthesis in plants will be potentially useful in efforts to produce new antimicrobial compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantitative comparison of topical aluminum salt solution efficacy for management of sweating: a randomized, controlled trial.

PubMed

Swary, Jillian H; West, Dennis P; Kakar, Rohit; Ortiz, Sara; Schaeffer, Matthew R; Veledar, Emir; Alam, Murad

2015-12-01

There is a lack of studies objectively comparing the efficacy of topical antiperspirants in reducing sweat. To objectively and quantitatively compare the efficacy of two aluminum salt solutions for the reduction of induced sweating. A subject, rater, and statistician-blinded, randomized, controlled trial. Nineteen subjects were exposed to a standardized heat challenge for 3 h. Topical agent A (20% aluminum chloride hexahydrate) was randomized to either axilla, and topical agent B (1% aluminum acetate) assigned to the contralateral side. A sauna suit induced sweating during three 30-min heat intervals: (1) with no study agents (pre); (2) with both study agents, one on each side; and (3) after the agents were washed off (post). Sweat levels were measured by securing Whatman(®) filter paper to each axilla and measuring the paper weight after each heat interval. The difference in paper weight following each heat interval between Study Agent A and Study Agent B was measured by a gravimetric scale. Topical agent A had a significantly greater effect at reducing axillary sweating than B (P = 0.0002). In a sweating simulation, 20% aluminum chloride hexahydrate quantitatively and objectively appeared to reduce sweat more effectively than 1% aluminum acetate. © 2015 Wiley Periodicals, Inc.

Evolution of hemostatic agents in surgical practice

PubMed Central

Sundaram, Chandru P.; Keenan, Alison C.

2010-01-01

Objective: Topical hemostatic agents are used in a wide variety of surgical settings, and the evolution of this class of surgical tools is an interesting topic. We reviewed and outlined the historical progress of topical hemostats into present day surgery and urology, and highlight opportunities for future research. Materials and Methods: A MEDLINE search of all available literature concerning several classes of topical hemostatic agents was performed. Fibrins sealants, Gelatin sponge hemostatics, cyanoacrylate adhesives, oxidized regenerated cellulose, and microfibrillar collagen were included. References were chosen from a broad range of surgical literature. Results: Topical hemostatic agents have historically taken advantage of a wide variety of mechanisms for hemostasis. Fibrin sealants have a rich history and large potential for further applications. Gelatin sponge hemostatics have been widely used since their introduction, but have changed little. Cyanoacrylate adhesives have a unique mechanism and opportunity for novel applications of existing products. Oxidized cellulose was original in the use of plant-based components. Microfibrillar collagen hemostats have evolved to a wide variety of formats. Conclusions: A review of the evolution of topical hemostatic agents highlights opportunities for potential novel research. Fibrin sealants may have the most opportunity for advancement, and understanding the history of these products is useful. With the drive in urology for minimally invasive surgical techniques, adaptation of topical hemostatic agents to this surgical approach would be valuable and offers an opportunity for novel contributions. PMID:21116358

A Review of Antibacterial Agents in Endodontic Treatment

PubMed Central

Rahimi, Saeed; Janani, Maryam; Lotfi, Mehrdad; Shahi, Shahriar; Aghbali, Amirala; Vahid Pakdel, Mahdi; Salem Milani, Amin; Ghasemi, Negin

2014-01-01

Microorganisms play a major role in initiation and perpetuation of pulpal and periapical diseases. Therefore, elimination of the microorganisms present in the root canal system is the fundamental objective of endodontic treatment. The use of mechanical debridement, chemical irrigation or other antimicrobial protocols and intra-canal medicaments are critical to attain this goal. The aim of this article was to review the antimicrobial agents and their properties in endodontics. PMID:25031587

Repurposing Toremifene for Treatment of Oral Bacterial Infections.

PubMed

Gerits, Evelien; Defraine, Valerie; Vandamme, Katleen; De Cremer, Kaat; De Brucker, Katrijn; Thevissen, Karin; Cammue, Bruno P A; Beullens, Serge; Fauvart, Maarten; Verstraeten, Natalie; Michiels, Jan

2017-03-01

The spread of antibiotic resistance and the challenges associated with antiseptics such as chlorhexidine have necessitated a search for new antibacterial agents against oral bacterial pathogens. As a result of failing traditional approaches, drug repurposing has emerged as a novel paradigm to find new antibacterial agents. In this study, we examined the effects of the FDA-approved anticancer agent toremifene against the oral bacteria Porphyromonas gingivalis and Streptococcus mutans We found that the drug was able to inhibit the growth of both pathogens, as well as prevent biofilm formation, at concentrations ranging from 12.5 to 25 μM. Moreover, toremifene was shown to eradicate preformed biofilms at concentrations ranging from 25 to 50 μM. In addition, we found that toremifene prevents P. gingivalis and S. mutans biofilm formation on titanium surfaces. A time-kill study indicated that toremifene is bactericidal against S. mutans Macromolecular synthesis assays revealed that treatment with toremifene does not cause preferential inhibition of DNA, RNA, or protein synthesis pathways, indicating membrane-damaging activity. Biophysical studies using fluorescent probes and fluorescence microscopy further confirmed the membrane-damaging mode of action. Taken together, our results suggest that the anticancer agent toremifene is a suitable candidate for further investigation for the development of new treatment strategies for oral bacterial infections. Copyright © 2017 American Society for Microbiology.