Antimicrobial topical agents used in the vagina.

PubMed

Frey Tirri, Brigitte

2011-01-01

Vaginally applied antimicrobial agents are widely used in the vagina in women with lower genital tract infections. An 'antimicrobial' is a general term that refers to a group of drugs that are effective against bacteria, fungi, viruses and protozoa. Topical treatments can be prescribed for a wide variety of vaginal infections. Many bacterial infections, such as bacterial vaginosis, desquamative inflammatory vaginitis or, as some European authors call it, aerobic vaginitis as well as infection with Staphylococcus aureus or group A streptococci, may be treated in this way. Candida vulvovaginitis is a fungal infection that is very amenable to topical treatment. The most common viral infections which can be treated with topical medications are condylomata acuminata and herpes simplex. The most often encountered protozoal vaginitis, which is caused by Trichomonas vaginalis, may be susceptible to topical medications, although this infection is treated systemically. This chapter covers the wide variety of commonly used topical antimicrobial agents for these diseases and focuses on the individual therapeutic agents and their clinical efficacy. In addition, potential difficulties that can occur in practice, as well as the usage of these medications in the special setting of pregnancy, are described in this chapter. Copyright © 2011 S. Karger AG, Basel.

Periodontal therapy using local delivery of antimicrobial agents.

PubMed

Niederman, Richard; Abdelshehid, George; Goodson, J Max

2002-10-01

Antimicrobial agents, systemic and/or local, are thought by some to be effective agents for treating periodontal infections. Here the authors determine the costs and benefits of local delivery agents for treating periodontal disease. Applying this cost-benefit analysis to patient care, however, will depend upon a clinician's expertise and a patient's value system.

Essential oils as natural food antimicrobial agents: a review.

PubMed

Vergis, Jess; Gokulakrishnan, P; Agarwal, R K; Kumar, Ashok

2015-01-01

Food-borne illnesses pose a real scourge in the present scenario as the consumerism of packaged food has increased to a great extend. Pathogens entering the packaged foods may survive longer, which needs a check. Antimicrobial agents either alone or in combination are added to the food or packaging materials for this purpose. Exploiting the antimicrobial property, essential oils are considered as a "natural" remedy to this problem other than its flavoring property instead of using synthetic agents. The essential oils are well known for its antibacterial, antiviral, antimycotic, antiparasitic, and antioxidant properties due to the presence of phenolic functional group. Gram-positive organisms are found more susceptible to the action of the essential oils. Essential oils improve the shelf-life of packaged products, control the microbial growth, and unriddle the consumer concerns regarding the use of chemical preservatives. This review is intended to provide an overview of the essential oils and their role as natural antimicrobial agents in the food industry.

World Health Organization Ranking of Antimicrobials According to Their Importance in Human Medicine: A Critical Step for Developing Risk Management Strategies to Control Antimicrobial Resistance From Food Animal Production.

PubMed

Collignon, Peter C; Conly, John M; Andremont, Antoine; McEwen, Scott A; Aidara-Kane, Awa; Agerso, Yvonne; Andremont, Antoine; Collignon, Peter; Conly, John; Dang Ninh, Tran; Donado-Godoy, Pilar; Fedorka-Cray, Paula; Fernandez, Heriberto; Galas, Marcelo; Irwin, Rebecca; Karp, Beth; Matar, Gassan; McDermott, Patrick; McEwen, Scott; Mitema, Eric; Reid-Smith, Richard; Scott, H Morgan; Singh, Ruby; DeWaal, Caroline Smith; Stelling, John; Toleman, Mark; Watanabe, Haruo; Woo, Gun-Jo

2016-10-15

Antimicrobial use in food animals selects for antimicrobial resistance in bacteria, which can spread to people. Reducing use of antimicrobials-particularly those deemed to be critically important for human medicine-in food production animals continues to be an important step for preserving the benefits of these antimicrobials for people. The World Health Organization ranking of antimicrobials according to their relative importance in human medicine was recently updated. Antimicrobials considered the highest priority among the critically important antimicrobials were quinolones, third- and fourth-generation cephalosporins, macrolides and ketolides, and glycopeptides. The updated ranking allows stakeholders in the agriculture sector and regulatory agencies to focus risk management efforts on drugs used in food animals that are the most important to human medicine. In particular, the current large-scale use of fluoroquinolones, macrolides, and third-generation cephalosporins and any potential use of glycopeptides and carbapenems need to be addressed urgently. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Silanols, a New Class of Antimicrobial Agent

DTIC Science & Technology

2006-04-01

carbinols against the four bacteria was log (1/MLC) = 0.670 log P + 0.0035 ∆ν -1.836, n = 282, r = 0.96, s = 0.22. This equation and a significantly...activity relationship of antimicrobial agents by means of equations [8] based on a method proposed by Hansch and Fujita in 1964 [1]. This multiple...correlation equations between their antimicrobial activities and structural properties, log P and H-bond acidity, were created by a multiple regression

Antimicrobial and physical characteristics of orthodontic primers containing antimicrobial agents.

PubMed

Chung, Shin-Hye; Cho, Soha; Kim, Kyungsun; Lim, Bum-Soon; Ahn, Sug-Joon

2017-03-01

To compare the antimicrobial and physical properties of experimental primers containing chlorhexidine (CHX) or ursolic acid (UA) with a commercial primer. Two antibacterial agents, 3 mg each of CHX and UA were incorporated respectively into 1 ml of Transbond XT primer (TX) to form antibacterial primers, TX-CHX and TX-UA. The antimicrobial activity of the three primers (TX, TX-CHX, and TX-UA) against Streptococcus mutans in both planktonic and biofilm phases was analyzed by determining minimum inhibitory and bactericidal concentrations and by performing growth and biofilm assays. Growth and biofilm assays were performed in both the absence and presence of thermocycling in a water tank to analyze the effects of water aging on the antimicrobial activities of primers. After bonding brackets onto bovine incisors using the primers, shear bond strength and mode of fracture were analyzed to compare physical properties. TX-CHX had stronger antimicrobial activity against S. mutans in the planktonic and biofilm phases than did TX or TX-UA. When applied, TX-CHX completely inhibited the growth and biofilm formation of S. mutans . In addition, the antimicrobial activity of TX-CHX was maintained after thermocycling. However, TX-UA did not show significant antimicrobial activity compared with TX. There was no significant difference in either shear bond strength or bond failure interface among the primers. Incorporation of CHX into an orthodontic primer may help prevent enamel demineralization around surfaces without compromising its physical properties.

Development of non-natural flavanones as antimicrobial agents.

PubMed

Fowler, Zachary L; Shah, Karan; Panepinto, John C; Jacobs, Amy; Koffas, Mattheos A G

2011-01-01

With growing concerns over multidrug resistance microorganisms, particularly strains of bacteria and fungi, evolving to become resistant to the antimicrobial agents used against them, the identification of new molecular targets becomes paramount for novel treatment options. Recently, the use of new treatments containing multiple active ingredients has been shown to increase the effectiveness of existing molecules for some infections, often with these added compounds enabling the transport of a toxic molecule into the infecting species. Flavonoids are among the most abundant plant secondary metabolites and have been shown to have natural abilities as microbial deterrents and anti-infection agents in plants. Combining these ideas we first sought to investigate the potency of natural flavonoids in the presence of efflux pump inhibitors to limit Escherichia coli growth. Then we used the natural flavonoid scaffold to synthesize non-natural flavanone molecules and further evaluate their antimicrobial efficacy on Escherichia coli, Bacillus subtilis and the fungal pathogens Cryptococcus neoformans and Aspergillus fumigatus. Of those screened, we identified the synthetic molecule 4-chloro-flavanone as the most potent antimicrobial compound with a MIC value of 70 µg/mL in E. coli when combined with the inhibitor Phe-Arg-ß-naphthylamide, and MICs of 30 µg/mL in S. cerevesiae and 30 µg/mL in C. neoformans when used alone. Through this study we have demonstrated that combinatorial synthesis of non-natural flavonones can identify novel antimicrobial agents with activity against bacteria and fungi but with minimal toxicity to human cells.

Development of Non-Natural Flavanones as Antimicrobial Agents

PubMed Central

Fowler, Zachary L.; Shah, Karan; Panepinto, John C.; Jacobs, Amy; Koffas, Mattheos A. G.

2011-01-01

With growing concerns over multidrug resistance microorganisms, particularly strains of bacteria and fungi, evolving to become resistant to the antimicrobial agents used against them, the identification of new molecular targets becomes paramount for novel treatment options. Recently, the use of new treatments containing multiple active ingredients has been shown to increase the effectiveness of existing molecules for some infections, often with these added compounds enabling the transport of a toxic molecule into the infecting species. Flavonoids are among the most abundant plant secondary metabolites and have been shown to have natural abilities as microbial deterrents and anti-infection agents in plants. Combining these ideas we first sought to investigate the potency of natural flavonoids in the presence of efflux pump inhibitors to limit Escherichia coli growth. Then we used the natural flavonoid scaffold to synthesize non-natural flavanone molecules and further evaluate their antimicrobial efficacy on Escherichia coli, Bacillus subtilis and the fungal pathogens Cryptococcus neoformans and Aspergillus fumigatus. Of those screened, we identified the synthetic molecule 4-chloro-flavanone as the most potent antimicrobial compound with a MIC value of 70 µg/mL in E. coli when combined with the inhibitor Phe-Arg-ß-naphthylamide, and MICs of 30 µg/mL in S. cerevesiae and 30 µg/mL in C. neoformans when used alone. Through this study we have demonstrated that combinatorial synthesis of non-natural flavonones can identify novel antimicrobial agents with activity against bacteria and fungi but with minimal toxicity to human cells. PMID:22039419

Current and future challenges in the development of antimicrobial agents.

PubMed

Rennie, Robert P

2012-01-01

Micro-organisms exist to survive. Even in the absence of antimicrobial agents, many have determinants of resistance that may be expressed phenotypically, should the need arise. With the advent of the antibiotic age, as more and more drugs were developed to treat serious infections, micro-organisms (particularly bacteria) rapidly developed resistance determinants to prevent their own demise.The most important determinants of resistance have been in the Gram-positive and Gram-negative bacteria. Among Gram-positive bacteria, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and penicillin-resistant Streptococcus pneumoniae (PRSP) have taxed researchers and pharmaceutical companies to develop new agents that are effective against these resistant strains. Among the Gram-negative bacteria, extended-spectrum beta-lactamase (ESBL) enzymes, carbapenemases (CREs) and the so-called amp-C enzymes that may be readily transferred between species of enterobacteriaceae and other facultative species have created multi-drug resistant organisms that are difficult to treat. Other resistance determinants have been seen in other clinically important bacterial species such as Neisseria gonorrhoeae, Clostridium difficile, Haemophilus influenzae and Mycobacterium tuberculosis. These issues have now spread to fungal agents of infection.A variety of modalities have been used to stem the tide of resistance. These include the development of niche compounds that target specific resistance determinants. Other approaches have been to find new targets for antimicrobial activity, use of combination agents that are effective against more than one target in the cell, or new delivery mechanism to maximize the concentration of antimicrobial agents at the site of infection without causing toxicity to the host. It is important that such new modalities have been proved effective for clinical therapy. Animal models and non-mammalian systems have been developed to

Modified lysozymes as novel broad spectrum natural antimicrobial agents in foods.

PubMed

Aminlari, Ladan; Hashemi, Marjan Mohammadi; Aminlari, Mahmoud

2014-06-01

In recent years much attention and interest have been directed toward application of natural antimicrobial agents in foods. Some naturally occurring proteins such as lactoperoxidase, lactoferrin, and lysozyme have received considerable attention and are being considered as potential antimicrobial agents in foods. Lysozyme kills bacteria by hydrolyzing the peptidoglycan layer of the cell wall of certain bacterial species, hence its application as a natural antimicrobial agent has been suggested. However, limitations in the action of lysozyme against only Gram-positive bacteria have prompted scientists to extend the antimicrobial effects of lysozyme by several types of chemical modifications. During the last 2 decades extensive research has been directed toward modification of lysozyme in order to improve its antimicrobial properties. This review will report on the latest information available on lysozyme modifications and examine the applicability of the modified lysozymes in controlling growth of Gram-positive and Gram-negative bacteria in foods. The results of modifications of lysozyme using its conjugation with different small molecule, polysaccharides, as well as modifications using proteolytic enzymes will be reviewed. These types of modifications have not only increased the functional properties of lysozyme (such as solubility and heat stability) but also extended the antimicrobial activity of lysozyme. Many examples will be given to show that modification can decrease the count of Gram-negative bacteria in bacterial culture and in foods by as much as 5 log CFU/mL and in some cases essentially eliminated Escherichia coli. In conclusion this review demonstrates that modified lysozymes are excellent natural food preservatives, which can be used in food industry. The subject described in this review article can lead to the development of methods to produce new broad-spectrum natural antimicrobial agents, based on modification of chicken egg white lysozyme, which

Macromolecular agents with antimicrobial potentialities: A drive to combat antimicrobial resistance.

PubMed

Bilal, Muhammad; Rasheed, Tahir; Iqbal, Hafiz M N; Hu, Hongbo; Wang, Wei; Zhang, Xuehong

2017-10-01

In recent years, the antimicrobial resistance (AMR) or multidrug resistance (MDR) has become a serious health concern and major challenging issue, worldwide. After decades of negligence, the AMR has now captured global attention. The increasing number of antibiotic-resistant strains has threatened the achievements of science and medicine since it inactivates conventional antimicrobial therapeutics. Scientists are trying to respond to AMR/MDR threat by exploring innovative platforms and new therapeutic strategies to tackle infections from these resistant strains and bypass treatment limitations related to these pathologies. The present review focuses on the utilization of bio-inspired novel constructs and their potential applications as novel antimicrobial agents. The first part of the review describes plant-based biological macromolecules containing an immense variety of secondary metabolites, which could be potentially used as alternative strategies to combat antimicrobial resistance. The second part discusses the potential of metal-based macromolecules as effective antimicrobial platforms for preventing infections from resistant strains. The third part comprehensively elucidates how nanoparticles, in particular, metal-integrated nanoparticles can overcome this AMR or MDR issue. Towards the end, information is given with critical concluding remarks, gaps, and finally envisioned with future considerations. Copyright © 2017 Elsevier B.V. All rights reserved.

Inhibition of Legionella pneumophila multiplication within human macrophages by antimicrobial agents.

PubMed Central

Vildé, J L; Dournon, E; Rajagopalan, P

1986-01-01

The activity of serial concentrations of different antimicrobial agents on the multiplication of Legionella pneumophila within human monocyte-derived macrophages was studied. The results led to the definition of a minimal extracellular concentration inhibiting intracellular multiplication (MIEC). According to the MIECs, the antimicrobial agents tested were classified in three groups: very active (MIEC less than or equal to 0.06 microgram/ml), such as erythromycin, rifampin, and pefloxacin; active (1 microgram/ml greater than or equal to MIEC greater than or equal to 0.1 microgram/ml), such as sulfamethoxazole-trimethoprim or doxycycline; and ineffective, such as cefoxitin, which was not active within macrophages at as high as 64 micrograms/ml despite a low MIC (0.2 microgram/ml) on bacterial charcoal-yeast extract agar. The activity of netilmicin was difficult to assess because of its effect on extracellular legionellae. Combinations of erythromycin with rifampin and pefloxacin with erythromycin, rifampin, doxycycline, or netilmicin showed an additive effect and no antagonism. These results obtained in a cellular model are in agreement with the efficacy of antimicrobial agents in experimental infections and in Legionnaires disease. They sustain clinical interest in the new quinolones, such as pefloxacin, and in combinations of antimicrobial agents for the treatment of Legionnaires disease. PMID:3492176

Electrospun composite nanofiber fabrics containing uniformly dispersed antimicrobial agents as an innovative type of polymeric materials with superior antimicrobial efficacy.

PubMed

Sun, Xinbo; Zhang, Lifeng; Cao, Zhengbing; Deng, Ying; Liu, Li; Fong, Hao; Sun, Yuyu

2010-04-01

Herein we report that electrospun composite nanofiber fabrics containing uniformly dispersed antimicrobial agents and having large surface-to-mass ratios are an innovative type of antimicrobial polymeric materials with durable, nonleachable, and biocompatible characteristics, and more importantly, superior antimicrobial efficacy. Specifically, electrospun cellulose acetate (CA) nanofiber fabrics containing an N-halamine antimicrobial agent of bis(N-chloro-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Cl-BTMP) were prepared and evaluated; the results of antimicrobial efficacy indicated that the electrospun composite nanofiber fabrics substantially outperformed the control samples that were solution-cast films containing identical amounts of CA and Cl-BTMP. Additionally, the results of trypan blue assay test suggested that the electrospun composite nanofiber fabrics also had excellent mammal cell viability. The developed electrospun composite nanofiber fabrics with superior antimicrobial efficacy are expected to find vital applications in biomedical, hygienic, and many other fields.

Animal venoms as antimicrobial agents.

PubMed

Perumal Samy, Ramar; Stiles, Bradley G; Franco, Octavio L; Sethi, Gautam; Lim, Lina H K

2017-06-15

Hospitals are breeding grounds for many life-threatening bacteria worldwide. Clinically associated gram-positive bacteria such as Staphylococcus aureus/methicillin-resistant S. aureus and many others increase the risk of severe mortality and morbidity. The failure of antibiotics to kill various pathogens due to bacterial resistance highlights the urgent need to develop novel, potent, and less toxic agents from natural sources against various infectious agents. Currently, several promising classes of natural molecules from snake (terrestrial and sea), scorpion, spider, honey bee and wasp venoms hold promise as rich sources of chemotherapeutics against infectious pathogens. Interestingly, snake venom-derived synthetic peptide/snake cathelicidin not only has potent antimicrobial and wound-repair activity but is highly stable and safe. Such molecules are promising candidates for novel venom-based drugs against S. aureus infections. The structure of animal venom proteins/peptides (cysteine rich) consists of hydrophobic α-helices or β-sheets that produce lethal pores and membrane-damaging effects on bacteria. All these antimicrobial peptides are under early experimental or pre-clinical stages of development. It is therefore important to employ novel tools for the design and the development of new antibiotics from the untapped animal venoms of snake, scorpion, and spider for treating resistant pathogens. To date, snail venom toxins have shown little antibiotic potency against human pathogens. Copyright © 2017 Elsevier Inc. All rights reserved.

Animal Venom Peptides: Potential for New Antimicrobial Agents.

PubMed

Primon-Barros, Muriel; José Macedo, Alexandre

2017-01-01

Microbial infections affect people worldwide, causing diseases with significant impact on public health, indicating the need for research and development of new antimicrobial agents. Animal venoms represent a vast and largely unexploited source of biologically active molecules with attractive candidates for the development of novel therapeutics. Venoms consist of complex mixtures of molecules, including antimicrobial peptides (AMPs). Since the discovery of AMPs, they have been studied as promising new antimicrobial drugs. Amongst the remarkable sources of AMPs with known antimicrobial activities are ants, bees, centipedes, cone snails, scorpions, snakes, spiders, and wasps. The antimicrobial tests against bacteria, protozoans, fungi and viruses using 170 different peptides isolated directly from crude venoms or cDNA libraries of venom glands are listed and discussed in this review, as well as hemolytic ativity. The potential of venoms as source of new compounds, including AMPs, is extensively discussed. Currently, there are six FDA-approved drugs and many others are undergoing preclinical and clinical trials. The search for antimicrobial "weapons" makes the AMPs from venoms promising candidates. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Supramolecular reactive sulphur nanoparticles: a novel and efficient antimicrobial agent.

PubMed

Roy Choudhury, S; Goswami, A

2013-01-01

Antimicrobial resistance continues to be an inexorable threat for the biomedical and biochemical researchers. Despite the novel discoveries in drug designing and delivery, high-throughput screening and surveillance data render the prospects for new antimicrobial agents as bleak as ever. The advent of nanotechnology, however, strengthens pharmacology by offering effective therapeutics to treat this aforementioned problem. Several nanoparticles of the known elements have already been reported for their antimicrobial efficacy. Nanosized fabrication of elemental sulphur with suitable surface modifications offers to retrieve the use of sulphur (man's oldest known ecofriendly microbicide) as a potential antimicrobial agent. Sulphur nanoparticles (SNPs) are effective against both conventionally sulphur-resistant and sulphur-susceptible microbes (fungi and bacteria). Moreover, biocompatible polymers present on the surface of SNPs minimize toxicity during application. Here, we focus on various aspects of physicochemical features of SNPs and their biochemical interactions with microbes. The present review also illustrates the effects of SNPs on plants and animals in terms of cytotoxicity and biocompatibility. © 2012 The Society for Applied Microbiology.

Pharmacokinetic parameters explain the therapeutic activity of antimicrobial agents in a silkworm infection model.

PubMed

Paudel, Atmika; Panthee, Suresh; Urai, Makoto; Hamamoto, Hiroshi; Ohwada, Tomohiko; Sekimizu, Kazuhisa

2018-01-25

Poor pharmacokinetic parameters are a major reason for the lack of therapeutic activity of some drug candidates. Determining the pharmacokinetic parameters of drug candidates at an early stage of development requires an inexpensive animal model with few associated ethical issues. In this study, we used the silkworm infection model to perform structure-activity relationship studies of an antimicrobial agent, GPI0039, a novel nitrofuran dichloro-benzyl ester, and successfully identified compound 5, a nitrothiophene dichloro-benzyl ester, as a potent antimicrobial agent with superior therapeutic activity in the silkworm infection model. Further, we compared the pharmacokinetic parameters of compound 5 with a nitrothiophene benzyl ester lacking chlorine, compound 7, that exerted similar antimicrobial activity but had less therapeutic activity in silkworms, and examined the metabolism of these antimicrobial agents in human liver fractions in vitro. Compound 5 had appropriate pharmacokinetic parameters, such as an adequate half-life, slow clearance, large area under the curve, low volume of distribution, and long mean residence time, compared with compound 7, and was slowly metabolized by human liver fractions. These findings suggest that the therapeutic effectiveness of an antimicrobial agent in the silkworms reflects appropriate pharmacokinetic properties.

In vitro susceptibility of Trichomonas vaginalis to 50 antimicrobial agents.

PubMed Central

Sears, S D; O'Hare, J

1988-01-01

We determined the susceptibilities of five strains of Trichomonas vaginalis, one of which was metronidazole resistant, to 50 antimicrobial agents. For the metronidazole-susceptible strains, the most active agents were metronidazole, tinidazole, mebendazole, furazolidone, and anisomycin. Against the resistant strain mebendazole, furazolidone, and anisomycin were the most active. Antifungal agents, beta-lactams, macrolides, aminoglycosides, and folic acid antagonists were ineffective against all strains. PMID:3258142

Update on Monoterpenes as Antimicrobial Agents: A Particular Focus on p-Cymene

PubMed Central

Marchese, Anna; Arciola, Carla Renata; Barbieri, Ramona; Silva, Ana Sanches; Nabavi, Seyed Fazel; Tsetegho Sokeng, Arold Jorel; Izadi, Morteza; Jafari, Nematollah Jonaidi; Suntar, Ipek; Nabavi, Seyed Mohammad

2017-01-01

p-Cymene [1-methyl-4-(1-methylethyl)-benzene] is a monoterpene found in over 100 plant species used for medicine and food purposes. It shows a range of biological activity including antioxidant, anti-inflammatory, antinociceptive, anxiolytic, anticancer and antimicrobial effects. This last property has been widely investigated due to the urgent need for new substances with antimicrobial properties, to be used to treat communicable diseases whose diffusion in developed countries has been facilitated by globalization and the evolution of antimicrobial resistance. This review summarizes available scientific data, as reported by the most recent studies describing the antimicrobial activity of p-cymene either alone, or as the main component of plant extracts, as well as addressing the mechanisms of action of cymenes as antimicrobial agents. While p-cymene is one of the major constituents of extracts and essential oils used in traditional medicines as antimicrobial agents, but considering the limited data on its in vivo efficacy and safety, further studies are required to reach a definitive recommendation on the use and beneficial effects of p-cymene in human healthcare and in biomedical applications as a promising candidate to functionalize biomaterials and nanomaterials. PMID:28809799

Metal oxide nanoparticles as antimicrobial agents: a promise for the future.

PubMed

Raghunath, Azhwar; Perumal, Ekambaram

2017-02-01

Microbial infectious diseases are a global threat to human health. Excess and improper use of antibiotics has created antimicrobial-resistant microbes that can defy clinical treatment. The hunt for safe and alternate antimicrobial agents is on in order to overcome such resistant micro-organisms, and the birth of nanotechnology offers promise to combat infectious organisms. Over the past two decades, metal oxide nanoparticles (MeO-NPs) have become an attractive alternative source to combat microbes that are highly resistant to various classes of antibiotics. Their vast array of physicochemical properties enables MeO-NPs to act as antimicrobial agents through various mechanisms. Apart from exhibiting antimicrobial properties, MeO-NPs also serve as carriers of drugs, thus barely providing a chance for micro-organisms to develop resistance. These immense multiple properties exhibited by MeO-NPs will have an impact on the treatment of deadly infectious diseases. This review discusses the mechanisms of action of MeO-NPs against micro-organisms, safety concerns, challenges and future perspectives. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Variations in the sales and sales patterns of veterinary antimicrobial agents in 25 European countries.

PubMed

Grave, Kari; Torren-Edo, Jordi; Muller, Arno; Greko, Christina; Moulin, Gerard; Mackay, David

2014-08-01

To describe sales and sales patterns of veterinary antimicrobial agents in 25 European Union (EU)/European Economic Area (EEA) countries for 2011. Data on the sales of veterinary antimicrobial agents from 25 EU member states and EEA countries for 2011 were collected at package level (name, formulation, strength, pack size, number of packages sold) according to a standardized protocol and template and presented in a harmonized manner. These data were calculated to express amounts sold, in metric tonnes, of active ingredient of each package. A population correction unit (PCU) was applied as a proxy for the animal biomass potentially treated with antimicrobial agents. The indicator used to express sales was milligrams of active substance per PCU. Substantial variations in the sales patterns and in the magnitude of sales of veterinary antimicrobial agents, expressed as mg/PCU, between the countries were observed. The proportion of sales, in mg/PCU, of products applicable for treatment of groups or herds of animals (premixes, oral powders and oral solution) varied considerably between the countries. Some countries reported much lower sales of veterinary antimicrobial agents than others, when expressed as mg/PCU. Sales patterns varied between countries, particularly with respect to pharmaceutical forms. Further studies are needed to understand the factors that explain the observed differences. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Insights on antimicrobial resistance, biofilms and the use of phytochemicals as new antimicrobial agents.

PubMed

Borges, Anabela; Saavedra, Maria J; Simões, Manuel

2015-01-01

Antimicrobial resistance is one of the most serious public health problems. This is of particular concern when bacteria become resistant to various antimicrobial agents simultaneously and when they form biofilms. Consequently, therapeutic options for the treatment of infections have become limited, leading frequently to recurrent infections, treatment failure and increase of morbidity and mortality. Both, persistence and spread of antibiotic resistance, in combination with decreased effectiveness and increased toxicity of current antibiotics have emphasized the urgent need to search alternative sources of antimicrobial substances. Plants are recognized as a source of unexplored chemical structures with high therapeutic potential, including antimicrobial activity against clinically important microorganisms. Additionally, phytochemicals (plant secondary metabolites) present several advantages over synthetic molecules, including green status and different mechanisms of action from antibiotics which could help to overcome the resistance problem. In this study, an overview of the main classes of phytochemicals with antimicrobial properties and their mode of action is presented. A revision about the application of phytochemicals for biofilm prevention and control is also done. Moreover, the use of phytochemicals as scaffolds of new functional molecules to expand the antibiotics pipeline is reviewed.

Improved agar diffusion method for detecting residual antimicrobial agents.

PubMed

Tsai, C E; Kondo, F

2001-03-01

The improved agar diffusion method for determination of residual antimicrobial agents was investigated, and the sensitivities of various combinations of test organisms and assay media were determined using 7 organisms, 5 media, and 31 antimicrobial agents. Bacillus stearothermophilus and synthetic assay medium (SAM) showed the greatest sensitivity for screening penicillins (penicillin G and ampicillin). The combination of Bacillus subtilis and minimum medium (MM) was the most sensitive for tetracyclines (oxytetracycline and chlortetracycline), B. stearothermophilus and SAM or Micrococcus luteus and Mueller-Hinton agar (MHA) for detecting tylosin and erythromycin, B. subtilis and MHA for aminoglycosides (streptomycin, kanamycin, gentamicin, and dihydrostreptomycin), B. stearothermophilus and SAM for polyethers (salinomycin and lasalocid), and B. subtilis and MM or Clostridium perfringens and GAM for polypeptides (thiopeptin, enramycin, virginiamycin, and bacitracin). However, gram-negative bacterium Escherichia coli ATCC 27166 and MM were better for screening for colistin and polymixin-B. For detecting the synthetic drugs tested, the best combination was B. subtilis and MM for sulfonamides, E. coli 27166 and MM for quinolones (oxolinic acid and nalidixic acid), B. subtilis and MM for furans (furazolidone), and the bioluminescent bacterium Photobacterium phosphoreum and luminescence assay medium for chloramphenicol and oxolinic acid. The results showed that the use of four assay plates, B. stearothermophilus and SAM, B. subtilis and MM, M. luteus and MHA, and E. coli 27166 and MM, was superior to the currently available techniques for screening for residual antimicrobial agents in edible animal tissues.

A Global Declaration on Appropriate Use of Antimicrobial Agents across the Surgical Pathway.

PubMed

This declaration, signed by an interdisciplinary task force of 234 experts from 83 different countries with different backgrounds, highlights the threat posed by antimicrobial resistance and the need for appropriate use of antibiotic agents and antifungal agents in hospitals worldwide especially focusing on surgical infections. As such, it is our intent to raise awareness among healthcare workers and improve antimicrobial prescribing. To facilitate its dissemination, the declaration was translated in different languages.

Effect of clavulanic acid on minimal inhibitory concentrations of 16 antimicrobial agents tested against Legionella pneumophila.

PubMed Central

Pohlod, D J; Saravolatz, L D; Quinn, E L; Somerville, M M

1980-01-01

A total of 15 Legionella pneumophilia isolated were tested against 16 antimicrobial agents used singly and in combination with clavulanic acid. When combined with clavulanic acid, 4 of the 16 antimicrobial agents produced no enhanced effect. However, the minimal inhibitory concentrations of 12 of the antimicrobial agents were reduced by one-half to one-third when in combination with clavulanic acid. These reductions reflected only a one-dilution decrease, however, in the original minimal inhibitory concentrations. Thus, clavulanic acid combinations appear to be only nominally effective beta-lactamase inhibitors against L. pneumophilia. PMID:6969575

The In Vitro Antimicrobial Effects of Lavandula angustifolia Essential Oil in Combination with Conventional Antimicrobial Agents

PubMed Central

de Rapper, Stephanie; Viljoen, Alvaro

2016-01-01

The paper focuses on the in vitro antimicrobial activity of Lavandula angustifolia Mill. (lavender) essential oil in combination with four commercial antimicrobial agents. Stock solutions of chloramphenicol, ciprofloxacin, nystatin, and fusidic acid were tested in combination with L. angustifolia essential oil. The antimicrobial activities of the combinations were investigated against the Gram-positive bacterial strain Staphylococcus aureus (ATCC 6538) and Gram-negative Pseudomonas aeruginosa (ATCC 27858) and Candida albicans (ATCC 10231) was selected to represent the yeasts. The antimicrobial effect was performed using the minimum inhibitory concentration (MIC) microdilution assay. Isobolograms were constructed for varying ratios. The most prominent interaction was noted when L. angustifolia essential oil was combined with chloramphenicol and tested against the pathogen P. aeruginosa (ΣFIC of 0.29). Lavendula angustifolia essential oil was shown in most cases to interact synergistically with conventional antimicrobials when combined in ratios where higher volumes of L. angustifolia essential oil were incorporated into the combination. PMID:27891157

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.

Patterns of antimicrobial agent prescription in a sentinel population of canine and feline veterinary practices in the United Kingdom.

PubMed

Singleton, D A; Sánchez-Vizcaíno, F; Dawson, S; Jones, P H; Noble, P J M; Pinchbeck, G L; Williams, N J; Radford, A D

2017-06-01

Antimicrobial resistance is an increasingly important global health threat and the use of antimicrobial agents is a key risk factor in its development. This study describes antimicrobial agent prescription (AAP) patterns over a 2year period using electronic health records (EHRs) from booked consultations in a network of 457 sentinel veterinary premises in the United Kingdom. A semi-automated classification methodology was used to map practitioner defined product codes in 918,333 EHRs from 413,870 dogs and 352,730 EHRs from 200,541 cats, including 289,789 AAPs. AAP as a proportion of total booked consultations was more frequent in dogs (18.8%, 95% confidence interval, CI, 18.2-19.4) than cats (17.5%, 95% CI 16.9-18.1). Prescription of topical antimicrobial agents was more frequent in dogs (7.4%, 95% CI 7.2-7.7) than cats (3.2%, 95% CI 3.1-3.3), whilst prescription of systemic antimicrobial agents was more frequent in cats (14.8%, 95% CI 14.2-15.4) than dogs (12.2%, 95% CI 11.7-12.7). A decreasing temporal pattern was identified for prescription of systemic antimicrobial agents in dogs and cats. Premises which prescribed antimicrobial agents frequently for dogs also prescribed frequently for cats. AAP was most frequent during pruritus consultations in dogs and trauma consultations in cats. Clavulanic acid potentiated amoxicillin was the most frequently prescribed antimicrobial agent in dogs (28.6% of prescriptions, 95% CI 27.4-29.8), whereas cefovecin, a third generation cephalosporin, was the most frequently prescribed antimicrobial agent in cats (36.2%, 95% CI 33.9-38.5). This study demonstrated patterns in AAP over time and for different conditions in a population of companion animals in the United Kingdom. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Efficacy of antimicrobial agents incorporated in orthodontic bonding systems: a systematic review and meta-analysis.

PubMed

de Almeida, C M; da Rosa, W L O; Meereis, C T W; de Almeida, S M; Ribeiro, J S; da Silva, A F; Lund, Rafael Guerra

2018-06-01

The purpose of this study was to evaluate the efficacy of orthodontic bonding systems containing different antimicrobial agents, as well as the influence of antimicrobial agent incorporation in the bonding properties of these materials. Eight databases were searched: PubMed (Medline), Web of Science, Scopus, Lilacs, Ibecs, BBO, Scielo and Google Scholar. Any study that evaluated antimicrobial activity in experimental or commercial orthodontic bonding systems was included. Data were tabulated independently and in duplicated by two authors on pre-designed data collection form. The global analysis was carried out using a random-effects model, and pooled-effect estimates were obtained by comparing the standardised mean difference of each antimicrobial orthodontic adhesive with the respective control group. A p-value < .05 was considered as statistically significant. Thirty-two studies were included in the qualitative analysis; of these, 22 studies were included in the meta-analysis. Antimicrobial agents such as silver nanoparticles, benzalkonium chloride, chlorhexidine, triclosan, cetylpyridinium chloride, Galla chinensis extract, acid ursolic, dimethylaminododecyl methacrylate, dimethylaminohexadecyl methacrylate, 2-methacryloyloxyethyl phosphorylcholine, 1,3,5-triacryloylhexahydro-1,3,5-triazine, zinc oxide and titanium oxide have been incorporated into orthodontic bonding systems. The antimicrobial agent incorporation in orthodontic bonding systems showed higher antimicrobial activity than the control group in agar diffusion (overall standardised mean difference: 3.71; 95% CI 2.98 to 4.43) and optical density tests (0.41; 95% CI -0.05 to 0.86) (p < .05). However, for biofilm, the materials did not present antimicrobial activity (6.78; 95% CI 4.78 to 8.77). Regarding bond strength, the global analysis showed antimicrobial orthodontic bonding systems were statistically similar to the control. Although there is evidence of antibacterial activity from in vitro

Resistance of Staphylococcus aureus to antimicrobial agents in Ethiopia: a meta-analysis.

PubMed

Deyno, Serawit; Fekadu, Sintayehu; Astatkie, Ayalew

2017-01-01

Emergence of antimicrobial resistance by Staphylococcus aureus has limited treatment options against its infections. The purpose of this study was to determine the pooled prevalence of resistance to different antimicrobial agents by S. aureus in Ethiopia. Web-based search was conducted in the databases of PubMed, Google Scholar, Hinari, Scopus and the Directory of Open Access Journals (DOAJ) to identify potentially eligible published studies. Required data were extracted and entered into Excel spread sheet. Statistical analyses were performed using Stata version 13.0. The metaprop Stata command was used to pool prevalence values. Twenty-one separate meta-analysis were done to estimate the pooled prevalence of the resistance of S. aureus to twenty-one different antimicrobial agents. Heterogeneity among the studies was assessed using the I 2 statistic and chi-square test. Publication bias was assessed using Egger's test. Because of significant heterogeneity amongst the studies, the random effects model was used to pool prevalence values. The electronic database search yielded 1317 studies among which 45 studies met our inclusion criteria. Our analyses demonstrated very high level of resistance to amoxicillin (77% [95% confidence interval (CI): 68%, 0.85%]), penicillin (76% [95% CI: 67%, 84%]), ampicillin (75% [95% CI: 65%, 85%]), tetracycline (62% [95% CI: 55%, 68%]), methicillin (47% [95% CI: 33%, 61%]), cotrimoxaziole (47% [95% CI: 40%, 55%]), doxycycline (43% [95% CI: 26%, 60%]), and erythromycin (41% [95% CI: 29%, 54%]). Relatively low prevalence of resistance was observed with kanamycin (14% [95% CI: 5%, 25%]) and ciprofloxacin (19% [95% CI: 13%, 26%]). The resistance level to vancomycin is 11% 995% CI: (4%, 20%). High heterogeneity was observed for each of the meta-analysis performed (I 2 ranging from 79.36% to 95.93%; all p -values ≤0.01). Eggers' test did not show a significant publication bias for all antimicrobial agents except for erythromycin and

The effect of antimicrobial agents on bond strength of orthodontic adhesives: a meta-analysis of in vitro studies.

PubMed

Altmann, A S P; Collares, F M; Leitune, V C B; Samuel, S M W

2016-02-01

Antimicrobial orthodontic adhesives aim to reduce white spot lesions' incidence in orthodontic patients, but they should not jeopardizing its properties. Systematic review and meta-analysis were performed to answer the question whether the association of antimicrobial agents with orthodontic adhesives compromises its mechanical properties and whether there is a superior antimicrobial agent. PubMed and Scopus databases. In vitro studies comparing shear bond strength of conventional photo-activated orthodontic adhesives to antimicrobial photo-activated orthodontic adhesives were considered eligible. Search terms included the following: orthodontics, orthodontic, antimicrobial, antibacterial, bactericidal, adhesive, resin, resin composite, bonding agent, bonding system, and bond strength. The searches yielded 494 citations, which turned into 467 after duplicates were discarded. Titles and abstracts were read and 13 publications were selected for full-text reading. Twelve studies were included in the meta-analysis. The global analysis showed no statistically significant difference between control and experimental groups. In the subgroup analysis, only the chlorhexidine subgroup showed a statistically significant difference, where the control groups had higher bond strength than the experimental groups. Many studies on in vitro orthodontic bond strength fail to report test conditions that could affect their outcomes. The pooled in vitro data suggest that adding an antimicrobial agent to an orthodontic adhesive system does not influence bond strength to enamel. It is not possible to state which antimicrobial agent is better to be associated. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Prospects of Nanostructure Materials and Their Composites as Antimicrobial Agents

PubMed Central

Baranwal, Anupriya; Srivastava, Ananya; Kumar, Pradeep; Bajpai, Vivek K.; Maurya, Pawan K.; Chandra, Pranjal

2018-01-01

Nanostructured materials (NSMs) have increasingly been used as a substitute for antibiotics and additives in various products to impart microbicidal effect. In particular, use of silver nanoparticles (AgNPs) has garnered huge researchers' attention as potent bactericidal agent due to the inherent antimicrobial property of the silver metal. Moreover, other nanomaterials (carbon nanotubes, fullerenes, graphene, chitosan, etc.) have also been studied for their antimicrobial effects in order ensure their application in widespread domains. The present review exclusively emphasizes on materials that possess antimicrobial activity in nanoscale range and describes their various modes of antimicrobial action. It also entails broad classification of NSMs along with their application in various fields. For instance, use of AgNPs in consumer products, gold nanoparticles (AuNPs) in drug delivery. Likewise, use of zinc oxide nanoparticles (ZnO-NPs) and titanium dioxide nanoparticles (TiO2-NPs) as additives in consumer merchandises and nanoscale chitosan (NCH) in medical products and wastewater treatment. Furthermore, this review briefly discusses the current scenario of antimicrobial nanostructured materials (aNSMs), limitations of current research and their future prospects. To put various perceptive insights on the recent advancements of such antimicrobials, an extended table is incorporated, which describes effect of NSMs of different dimensions on test microorganisms along with their potential widespread applications. PMID:29593676

Self-assembled cationic peptide nanoparticles as an efficient antimicrobial agent

NASA Astrophysics Data System (ADS)

Liu, Lihong; Xu, Kaijin; Wang, Huaying; Jeremy Tan, P. K.; Fan, Weimin; Venkatraman, Subbu S.; Li, Lanjuan; Yang, Yi-Yan

2009-07-01

Antimicrobial cationic peptides are of interest because they can combat multi-drug-resistant microbes. Most peptides form α-helices or β-sheet-like structures that can insert into and subsequently disintegrate negatively charged bacterial cell surfaces. Here, we show that a novel class of core-shell nanoparticles formed by self-assembly of an amphiphilic peptide have strong antimicrobial properties against a range of bacteria, yeasts and fungi. The nanoparticles show a high therapeutic index against Staphylococcus aureus infection in mice and are more potent than their unassembled peptide counterparts. Using Staphylococcus aureus-infected meningitis rabbits, we show that the nanoparticles can cross the blood-brain barrier and suppress bacterial growth in infected brains. Taken together, these nanoparticles are promising antimicrobial agents that can be used to treat brain infections and other infectious diseases.

Effects of sub-minimum inhibitory concentrations of antimicrobial agents on Streptococcus mutans biofilm formation.

PubMed

Dong, Liping; Tong, Zhongchun; Linghu, Dake; Lin, Yuan; Tao, Rui; Liu, Jun; Tian, Yu; Ni, Longxing

2012-05-01

Many studies have demonstrated that sub-minimum inhibitory concentrations (sub-MICs) of antimicrobial agents can inhibit bacterial biofilm formation. However, the mechanisms by which antimicrobial agents at sub-MICs inhibit biofilm formation remain unclear. At present, most studies are focused on Gram-negative bacteria; however, the effects of sub-MICs of antimicrobial agents on Gram-positive bacteria may be more complex. Streptococcus mutans is a major cariogenic bacterium. In this study, the S. mutans growth curve as well as the expression of genes related to S. mutans biofilm formation were evaluated following treatment with 0.5× MIC of chlorhexidine (CHX), tea polyphenols and sodium fluoride (NaF), which are common anticaries agents. The BioFlux system was employed to generate a biofilm under a controlled flow. Morphological changes of the S. mutans biofilm were observed and analysed using field emission scanning electron microscopy and confocal laser scanning microscopy. The results indicated that these three common anticaries agents could significantly upregulate expression of the genes related to S. mutans biofilm formation, and S. mutans exhibited a dense biofilm with an extensive extracellular matrix following treatment with sub-MICs of NaF and CHX. These findings suggest that sub-MICs of anticaries agents favour S. mutans biofilm formation, which might encourage dental caries progression. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Efficacy of Antimicrobial Agents for Food Contact Applications: Biological Activity, Incorporation into Packaging, and Assessment Methods: A Review.

PubMed

Mousavi Khaneghah, Amin; Hashemi, Seyed Mohammad Bagher; Eş, Ismail; Fracassetti, Daniela; Limbo, Sara

2018-07-01

Interest in the utilization of antimicrobial active packaging for food products has increased in recent years. Antimicrobial active packaging involves the incorporation of antimicrobial compounds into packaging materials, with the aim of maintaining or extending food quality and shelf life. Plant extracts, essential oils, organic acids, bacteriocins, inorganic substances, enzymes, and proteins are used as antimicrobial agents in active packaging. Evaluation of the antimicrobial activity of packaging materials using different methods has become a critical issue for both food safety and the commercial utilization of such packaging technology. This article reviews the different types of antimicrobial agents used for active food packaging materials, the main incorporation techniques, and the assessment methods used to examine the antimicrobial activity of packaging materials, taking into account their safety as food contact materials.

Carbon nanotubes as antimicrobial agents for water disinfection and pathogen control.

PubMed

Liu, Dan; Mao, Yiqin; Ding, Lijun

2018-04-01

Waterborne diseases significantly affect human health and are responsible for high mortality rates worldwide. Antibiotics have been known for decades for treatment of bacterial strains and their overuse and irrational applications are causing increasing bacteria resistance. Therefore, there is a strong need to find alternative ways for efficient water disinfection and microbial control. Carbon nanotubes (CNTs) have demonstrated strong antimicrobial properties due to their remarkable structure. This paper reviews the antimicrobial properties of CNTs, discusses diverse mechanisms of action against microorganisms as well as their applicability for water disinfection and microbial control. Safety concerns, challenges of CNTs as antimicrobial agents and future opportunities for their application in the water remediation process are also highlighted.

Essential oils and metal ions as alternative antimicrobial agents: a focus on tea tree oil and silver.

PubMed

Low, Wan-Li; Kenward, Ken; Britland, Stephen T; Amin, Mohd Cim; Martin, Claire

2017-04-01

The increasing occurrence of hospital-acquired infections and the emerging problems posed by antibiotic-resistant microbial strains have both contributed to the escalating cost of treatment. The presence of infection at the wound site can potentially stall the healing process at the inflammatory stage, leading to the development of a chronic wound. Traditional wound treatment regimes can no longer cope with the complications posed by antibiotic-resistant strains; hence, there is a need to explore the use of alternative antimicrobial agents. Pre-antibiotic compounds, including heavy metal ions and essential oils, have been re-investigated for their potential use as effective antimicrobial agents. Essential oils have potent antimicrobial, antifungal, antiviral, anti-inflammatory, antioxidant and other beneficial therapeutic properties. Similarly, heavy metal ions have also been used as disinfecting agents because of their broad spectrum activities. Both of these alternative antimicrobials interact with many different intracellular components, thereby resulting in the disruption of vital cell functions and eventually cell death. This review will discuss the application of essential oils and heavy metal ions, particularly tea tree oil and silver ions, as alternative antimicrobial agents for the treatment of chronic, infected wounds. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Pharmacogenomics of antimicrobial agents

PubMed Central

Aung, Ar Kar; Haas, David W; Hulgan, Todd; Phillips, Elizabeth J

2015-01-01

Antimicrobial efficacy and toxicity varies between individuals owing to multiple factors. Genetic variants that affect drug-metabolizing enzymes may influence antimicrobial pharmacokinetics and pharmacodynamics, thereby determining efficacy and/or toxicity. In addition, many severe immune-mediated reactions have been associated with HLA class I and class II genes. In the last two decades, understanding of pharmacogenomic factors that influence antimicrobial efficacy and toxicity has rapidly evolved, leading to translational success such as the routine use of HLA-B*57:01 screening to prevent abacavir hypersensitivity reactions. This article examines recent advances in the field of antimicrobial pharmacogenomics that potentially affect treatment efficacy and toxicity, and challenges that exist between pharmacogenomic discovery and translation into clinical use. PMID:25495412

Resistance profiles to antimicrobial agents in bacteria isolated from acute endodontic infections: systematic review and meta-analysis.

PubMed

Lang, Pauline M; Jacinto, Rogério C; Dal Pizzol, Tatiane S; Ferreira, Maria Beatriz C; Montagner, Francisco

2016-11-01

Infected root canal or acute apical abscess exudates can harbour several species, including Fusobacterium, Porphyromonas, Prevotella, Parvimonas, Streptococcus, Treponema, Olsenella and not-yet cultivable species. A systematic review and meta-analysis was performed to assess resistance rates to antimicrobial agents in clinical studies that isolated bacteria from acute endodontic infections. Electronic databases and the grey literature were searched up to May 2015. Clinical studies in humans evaluating the antimicrobial resistance of primary acute endodontic infection isolates were included. PRISMA guidelines were followed. A random-effect meta-analysis was employed. The outcome was described as the pooled resistance rates for each antimicrobial agent. Heterogeneity and sensitivity analyses were performed. Subgroup analyses were conducted based upon report or not of the use of antibiotics prior to sampling as an exclusion factor (subgroups A and B, respectively). Data from seven studies were extracted. Resistance rates for 15 different antimicrobial agents were evaluated (range, 3.5-40.0%). Lower resistance rates were observed for amoxicillin/clavulanic acid and amoxicillin; higher resistance rates were detected for tetracycline. Resistance rates varied according to previous use of an antimicrobial agent as demonstrated by the subgroup analyses. Heterogeneity was observed for the resistance profiles of penicillin G in subgroup A and for amoxicillin, clindamycin, metronidazole and tetracycline in subgroup B. Sensitivity analyses demonstrated that resistance rates changed for metronidazole, clindamycin, tetracycline and amoxicillin. These findings suggest that clinical isolates had low resistance to β-lactams. Further well-designed studies are needed to clarify whether the differences in susceptibility among the antimicrobial agents may influence clinical responses to treatment. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights

Susceptibilities of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum strains to antimicrobial agents in vitro.

PubMed Central

ter Laak, E A; Noordergraaf, J H; Verschure, M H

1993-01-01

The purpose of this study was to determine the susceptibility of various strains of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum, which are prevalent causes of pneumonia in calves, to 16 antimicrobial agents in vitro. The MICs of the antimicrobial agents were determined by a serial broth dilution method for 16 field strains and the type strain of M. bovis, for 19 field strains and the type strain of M. dispar, and for 17 field strains of U. diversum. Final MICs for M. bovis and M. dispar were read after 7 days and final MICs for U. diversum after 1 to 2 days. All strains tested were susceptible to tylosin, kitasamycin, and tiamulin but were resistant to nifuroquine and streptomycin. Most strains of U. diversum were intermediately susceptible to oxytetracycline but fully susceptible to chlortetracycline; most strains of M. bovis and M. dispar, however, were resistant to both agents. Strains of M. dispar and U. diversum were susceptible to doxycycline and minocycline, but strains of M. bovis were only intermediately susceptible. Susceptibility or resistance to chloramphenicol, spiramycin, spectinomycin, lincomycin, or enrofloxacin depended on the species but was not equal for the three species. The type strains of M. bovis and M. dispar were more susceptible to various antimicrobial agents, including tetracyclines, than the field strains. This finding might indicate that M. bovis and M. dispar strains are becoming resistant to these agents. Antimicrobial agents that are effective in vitro against all three mycoplasma species can be considered for treating mycoplasma infections in pneumonic calves. Therefore, tylosin, kitasamycin, and tiamulin may be preferred over oxytetracycline and chlortetracycline. PMID:8452363

Susceptibilities of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum strains to antimicrobial agents in vitro.

PubMed

ter Laak, E A; Noordergraaf, J H; Verschure, M H

1993-02-01

The purpose of this study was to determine the susceptibility of various strains of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum, which are prevalent causes of pneumonia in calves, to 16 antimicrobial agents in vitro. The MICs of the antimicrobial agents were determined by a serial broth dilution method for 16 field strains and the type strain of M. bovis, for 19 field strains and the type strain of M. dispar, and for 17 field strains of U. diversum. Final MICs for M. bovis and M. dispar were read after 7 days and final MICs for U. diversum after 1 to 2 days. All strains tested were susceptible to tylosin, kitasamycin, and tiamulin but were resistant to nifuroquine and streptomycin. Most strains of U. diversum were intermediately susceptible to oxytetracycline but fully susceptible to chlortetracycline; most strains of M. bovis and M. dispar, however, were resistant to both agents. Strains of M. dispar and U. diversum were susceptible to doxycycline and minocycline, but strains of M. bovis were only intermediately susceptible. Susceptibility or resistance to chloramphenicol, spiramycin, spectinomycin, lincomycin, or enrofloxacin depended on the species but was not equal for the three species. The type strains of M. bovis and M. dispar were more susceptible to various antimicrobial agents, including tetracyclines, than the field strains. This finding might indicate that M. bovis and M. dispar strains are becoming resistant to these agents. Antimicrobial agents that are effective in vitro against all three mycoplasma species can be considered for treating mycoplasma infections in pneumonic calves. Therefore, tylosin, kitasamycin, and tiamulin may be preferred over oxytetracycline and chlortetracycline.

In Vivo, In Vitro, and In Silico Characterization of Peptoids as Antimicrobial Agents.

PubMed

Czyzewski, Ann M; Jenssen, Håvard; Fjell, Christopher D; Waldbrook, Matt; Chongsiriwatana, Nathaniel P; Yuen, Eddie; Hancock, Robert E W; Barron, Annelise E

2016-01-01

Bacterial resistance to conventional antibiotics is a global threat that has spurred the development of antimicrobial peptides (AMPs) and their mimetics as novel anti-infective agents. While the bioavailability of AMPs is often reduced due to protease activity, the non-natural structure of AMP mimetics renders them robust to proteolytic degradation, thus offering a distinct advantage for their clinical application. We explore the therapeutic potential of N-substituted glycines, or peptoids, as AMP mimics using a multi-faceted approach that includes in silico, in vitro, and in vivo techniques. We report a new QSAR model that we developed based on 27 diverse peptoid sequences, which accurately correlates antimicrobial peptoid structure with antimicrobial activity. We have identified a number of peptoids that have potent, broad-spectrum in vitro activity against multi-drug resistant bacterial strains. Lastly, using a murine model of invasive S. aureus infection, we demonstrate that one of the best candidate peptoids at 4 mg/kg significantly reduces with a two-log order the bacterial counts compared with saline-treated controls. Taken together, our results demonstrate the promising therapeutic potential of peptoids as antimicrobial agents.

In Vivo, In Vitro, and In Silico Characterization of Peptoids as Antimicrobial Agents

PubMed Central

Fjell, Christopher D.; Waldbrook, Matt; Chongsiriwatana, Nathaniel P.; Yuen, Eddie; Hancock, Robert E. W.; Barron, Annelise E.

2016-01-01

Bacterial resistance to conventional antibiotics is a global threat that has spurred the development of antimicrobial peptides (AMPs) and their mimetics as novel anti-infective agents. While the bioavailability of AMPs is often reduced due to protease activity, the non-natural structure of AMP mimetics renders them robust to proteolytic degradation, thus offering a distinct advantage for their clinical application. We explore the therapeutic potential of N-substituted glycines, or peptoids, as AMP mimics using a multi-faceted approach that includes in silico, in vitro, and in vivo techniques. We report a new QSAR model that we developed based on 27 diverse peptoid sequences, which accurately correlates antimicrobial peptoid structure with antimicrobial activity. We have identified a number of peptoids that have potent, broad-spectrum in vitro activity against multi-drug resistant bacterial strains. Lastly, using a murine model of invasive S. aureus infection, we demonstrate that one of the best candidate peptoids at 4 mg/kg significantly reduces with a two-log order the bacterial counts compared with saline-treated controls. Taken together, our results demonstrate the promising therapeutic potential of peptoids as antimicrobial agents. PMID:26849681

Occurrence of antimicrobial agents, drug-resistant bacteria, and genes in the sewage-impacted Vistula River (Poland).

PubMed

Giebułtowicz, Joanna; Tyski, Stefan; Wolinowska, Renata; Grzybowska, Wanda; Zaręba, Tomasz; Drobniewska, Agata; Wroczyński, Piotr; Nałęcz-Jawecki, Grzegorz

2018-02-01

Antimicrobial agents (antimicrobials) are a group of therapeutic and hygienic agents that either kill microorganisms or inhibit their growth. Their occurrence in surface water may reveal harmful effects on aquatic biota and challenge microbial populations. Recently, there is a growing concern over the contamination of surface water with both antimicrobial agents and multidrug-resistant bacteria. The aim of the study was the determination of the presence of selected antimicrobials at specific locations of the Vistula River (Poland), as well as in tap water samples originating from the Warsaw region. Analysis was performed using the liquid chromatography-electrospray ionization-tandem mass spectrometry method. In addition, the occurrence of drug-resistant bacteria and resistance genes was determined using standard procedures. This 2-year study is the first investigation of the simultaneous presence of antimicrobial agents, drug-resistant bacteria, and genes in Polish surface water. In Poland, relatively high concentrations of macrolides are observed in both surface and tap water. Simultaneous to the high macrolide levels in the environment, the presence of the erm B gene, coding the resistance to macrolides, lincosamides, and streptogramin, was detected in almost all sampling sites. Another ubiquitous gene was int1, an element of the 5'-conserved segment of class 1 integrons that encode site-specific integrase. Also, resistant isolates of Enterococcus faecium and Enterococcus faecalis and Gram-negative bacteria were recovered. Multidrug-resistant bacteria isolates of Gram-negative and Enterococcus were also detected. The results show that wastewater treatment plants (WWTP) are the main source of most antimicrobials, resistant bacteria, and genes in the aquatic environment, probably due to partial purification during wastewater treatment processes.

All Natural and Clean-Label Preservatives and Antimicrobial Agents Used during Poultry Processing and Packaging.

PubMed

Grant, Ar'quette; Parveen, Salina

2017-04-01

The poultry industry is faced with compounding pressures of maintaining product safety and wholesomeness while keeping up with consumer trends of all-natural foods and label accuracy. Consumers are increasingly demanding that their foods be minimally processed and contain compounds that are easily read and recognized, i.e., products must be clean labeled. The purpose of this review is to briefly describe several natural antimicrobial agents that can be incorporated into poultry processing. These compounds and their essential oils were included in this mini-review because they are generally recognized as safe by the U.S. Food and Drug Administration and are considered clean label: thyme extract, rosemary extract, garlic, and oregano. This list of natural antimicrobial agents by no means includes all of the options available to poultry processors. Rather, this review provides a brief glance at the potential these natural antimicrobial agents have in terms of reduced pathogenicity, increased shelf stability, and sensory acceptability through direct product application or as part of the product packaging.

Fluoroquinolone antimicrobial agents.

PubMed Central

Wolfson, J S; Hooper, D C

1989-01-01

The fluoroquinolones, a new class of potent orally absorbed antimicrobial agents, are reviewed, considering structure, mechanisms of action and resistance, spectrum, variables affecting activity in vitro, pharmacokinetic properties, clinical efficacy, emergence of resistance, and tolerability. The primary bacterial target is the enzyme deoxyribonucleic acid gyrase. Bacterial resistance occurs by chromosomal mutations altering deoxyribonucleic acid gyrase and decreasing drug permeation. The drugs are bactericidal and potent in vitro against members of the family Enterobacteriaceae, Haemophilus spp., and Neisseria spp., have good activity against Pseudomonas aeruginosa and staphylococci, and (with several exceptions) are less potent against streptococci and have fair to poor activity against anaerobic species. Potency in vitro decreases in the presence of low pH, magnesium ions, or urine but is little affected by different media, increased inoculum, or serum. The effects of the drugs in combination with a beta-lactam or aminoglycoside are often additive, occasionally synergistic, and rarely antagonistic. The agents are orally absorbed, require at most twice-daily dosing, and achieve high concentrations in urine, feces, and kidney and good concentrations in lung, bone, prostate, and other tissues. The drugs are efficacious in treatment of a variety of bacterial infections, including uncomplicated and complicated urinary tract infections, bacterial gastroenteritis, and gonorrhea, and show promise for therapy of prostatitis, respiratory tract infections, osteomyelitis, and cutaneous infections, particularly when caused by aerobic gram-negative bacilli. Fluoroquinolones have also proved to be efficacious for prophylaxis against travelers' diarrhea and infection with gram-negative bacilli in neutropenic patients. The drugs are effective in eliminating carriage of Neisseria meningitidis. Patient tolerability appears acceptable, with gastrointestinal or central nervous

The management of risk arising from the use of antimicrobial agents in veterinary medicine in EU/EEA countries - a review.

PubMed

Törneke, K; Torren-Edo, J; Grave, K; Mackay, D K J

2015-12-01

Antimicrobials are essential medicines for the treatment of many microbial infections in humans and animals. Only a small number of antimicrobial agents with new mechanisms of action have been authorized in recent years for use in either humans or animals. Antimicrobial resistance (AMR) arising from the use of antimicrobial agents in veterinary medicine is a concern for public health due to the detection of increasing levels of resistance in foodborne zoonotic bacteria, particularly gram-negative bacteria, and due to the detection of determinants of resistance such as Extended-spectrum beta-lactamases (ESBL) in bacteria from animals and in foodstuffs of animal origin. The importance and the extent of the emergence and spread of AMR from animals to humans has yet to be quantified. Likewise, the relative contribution that the use of antimicrobial agents in animals makes to the overall risk to human from AMR is currently a subject of debate that can only be resolved through further research. Nevertheless, risk managers have agreed that the impact on public health of the use of antimicrobials in animals should be minimized as far as possible and a variety of measures have been introduced by different authorities in the EU to achieve this objective. This article reviews a range of measures that have been implemented within European countries to reduce the occurrence and the risk of transmission of AMR to humans following the use of antimicrobial agents in animals and briefly describes some of the alternatives to the use of antimicrobial agents that are being developed. © 2015 John Wiley & Sons Ltd.

Effective Treatment of Folliculitis Decalvans Using Selected Antimicrobial Agents

PubMed Central

Sillani, Caulloo; Bin, Zhang; Ying, Zhao; Zeming, Cai; Jian, Yang; Xingqi, Zhang

2010-01-01

Folliculitis Decalvans (FD) is a rare neutrophilic infammation of the scalp characterized by painful, recurrent purulent follicular exudation resulting in primary cicatricial alopecia. However, unclear etiology makes FD treatment a difficult task. A wide variety of topical and systemic agents have been tried previously, with varied results. We present here a case series report of a set of 13 patients with FD on antimicrobial therapy. PMID:21188019

Animals living in polluted environments are potential source of antimicrobials against infectious agents

PubMed Central

Lee, Simon; Siddiqui, Ruqaiyyah; Khan, Naveed Ahmed

2012-01-01

The antimicrobials crisis is a ticking time bomb which could lead to millions of people dying from untreatable infections. With the worsening trends of antimicrobial resistance, we are heading towards a pre-antibiotic era. Thus, there is a need for newer and more powerful antibiotic agents. The search for new antibiotic compounds originating from natural resources is a promising research area. Animals living in germ-infested environments are a potent source of antimicrobials. Under polluted milieus, organisms such as cockroaches encounter different types of bacteria, including superbugs. Such creatures survive the onslaught of superbugs and are able to ward off disease by producing antimicrobial substances which show potent activity in the nervous system. We hope that the discovery of antimicrobial activity in the cockroach brain will stimulate research in finding antimicrobials from unusual sources, and has potential for the development of novel antibiotics. Nevertheless, intensive research in the next few years will be required to approach or realize these expectations. PMID:23265422

Topical antimicrobial agents for treating foot ulcers in people with diabetes.

PubMed

Dumville, Jo C; Lipsky, Benjamin A; Hoey, Christopher; Cruciani, Mario; Fiscon, Marta; Xia, Jun

2017-06-14

People with diabetes are at high risk for developing foot ulcers, which often become infected. These wounds, especially when infected, cause substantial morbidity. Wound treatments should aim to alleviate symptoms, promote healing, and avoid adverse outcomes, especially lower extremity amputation. Topical antimicrobial therapy has been used on diabetic foot ulcers, either as a treatment for clinically infected wounds, or to prevent infection in clinically uninfected wounds. To evaluate the effects of treatment with topical antimicrobial agents on: the resolution of signs and symptoms of infection; the healing of infected diabetic foot ulcers; and preventing infection and improving healing in clinically uninfected diabetic foot ulcers. We searched the Cochrane Wounds Specialised Register, CENTRAL, Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations), Ovid Embase, and EBSCO CINAHL Plus in August 2016. We also searched clinical trials registries for ongoing and unpublished studies, and checked reference lists to identify additional studies. We used no restrictions with respect to language, date of publication, or study setting. We included randomised controlled trials conducted in any setting (inpatient or outpatient) that evaluated topical treatment with any type of solid or liquid (e.g., cream, gel, ointment) antimicrobial agent, including antiseptics, antibiotics, and antimicrobial dressings, in people with diabetes mellitus who were diagnosed with an ulcer or open wound of the foot, whether clinically infected or uninfected. Two review authors independently performed study selection, 'Risk of bias' assessment, and data extraction. Initial disagreements were resolved by discussion, or by including a third review author when necessary. We found 22 trials that met our inclusion criteria with a total of over 2310 participants (one study did not report number of participants). The included studies mostly had small numbers of participants (from 4 to 317

Appropriateness of gram-negative agent use at a tertiary care hospital in the setting of significant antimicrobial resistance.

PubMed

Vora, Neil M; Kubin, Christine J; Furuya, E Yoko

2015-01-01

Background.  Practicing antimicrobial stewardship in the setting of widespread antimicrobial resistance among gram-negative bacilli, particularly in urban areas, is challenging. Methods.  We conducted a retrospective cross-sectional study at a tertiary care hospital with an established antimicrobial stewardship program in New York, New York to determine appropriateness of use of gram-negative antimicrobials and to identify factors associated with suboptimal antimicrobial use. Adult inpatients who received gram-negative agents on 2 dates, 1 June 2010 or 1 December 2010, were identified through pharmacy records. Clinical data were collected for each patient. Use of gram-negative agents was deemed optimal or suboptimal through chart review and according to hospital guidelines. Data were compared using χ(2) or Fischer's exact test for categorical variables and Student t test or Mann-Whitney U test for continuous variables. Results.  A total of 356 patients were included who received 422 gram-negative agents. Administration was deemed suboptimal in 26% of instances, with the most common reason being spectrum of activity too broad. In multivariable analysis, being in an intensive care unit (adjusted odds ratio [aOR], .49; 95% confidence interval [CI], .29-.84), having an infectious diseases consultation within the previous 7 days (aOR, .52; 95% CI, .28-.98), and having a history of multidrug-resistant gram-negative bacilli within the past year (aOR, .24; 95% CI, .09-.65) were associated with optimal gram-negative agent use. Beta-lactam/beta-lactamase inhibitor combination drug use (aOR, 2.6; 95% CI, 1.35-5.16) was associated with suboptimal use. Conclusions.  Gram-negative agents were used too broadly despite numerous antimicrobial stewardship program activities.

Use of Computer-Assisted Instruction to Review Microbiology and Antimicrobial Agents.

ERIC Educational Resources Information Center

Carver, Peggy L.; And Others

1991-01-01

A study assessed the effectiveness of a microcomputer-assisted instructional program using graphics, color, and text in simulations to enhance pharmacy students' knowledge of microbiology and antimicrobial agents. Results indicated high short- and long-term retention of information presented and higher levels of knowledge and comprehension among…

Antimicrobial action of chelating agents: repercussions on the microorganism development, virulence and pathogenesis.

PubMed

Santos, A L S; Sodre, C L; Valle, R S; Silva, B A; Abi-Chacra, E A; Silva, L V; Souza-Goncalves, A L; Sangenito, L S; Goncalves, D S; Souza, L O P; Palmeira, V F; d'Avila-Levy, C M; Kneipp, L F; Kellett, A; McCann, M; Branquinha, M H

2012-01-01

Infections caused by resistant microorganisms often fail to respond to conventional therapy, resulting in prolonged illness, increased treatment costs and greater risk of death. Consequently, the development of novel antimicrobial drugs is becoming more demanding every day since the existing drugs either have too many side-effects or they tend to lose effectiveness due to the selection of resistant strains. In view of these facts, a number of new strategies to obstruct vital biological processes of a microbial cell have emerged; one of these is focused on the use of metal-chelating agents, which are able to selectively disturb the essential metal metabolism of the microorganism by interfering with metal acquisition and bioavailability for crucial reactions. The chelation activity is able to inhibit the biological role of metal-dependent proteins (e.g., metalloproteases and transcription factors), disturbing the microbial cell homeostasis and culminating in the blockage of microbial nutrition, growth and development, cellular differentiation, adhesion to biotic (e.g., extracellular matrix components, cell and/or tissue) and abiotic (e.g., plastic, silicone and acrylic) structures as well as controlling the in vivo infection progression. Interestingly, chelating agents also potentiate the activity of classical antimicrobial compounds. The differences between the microorganism and host in terms of the behavior displayed in the presence of chelating agents could provide exploitable targets for the development of an effective chemotherapy for these diseases. Consequently, metal chelators represent a novel group of antimicrobial agents with potential therapeutic applications. This review will focus on the anti-fungal and anti-protozoan action of the most common chelating agents, deciphering and discussing their mode of action.

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.

The in situ synthesis and application of silver nanoparticles as an antimicrobial agent for cotton fibers

USDA-ARS?s Scientific Manuscript database

The application of sliver (Ag) as an antimicrobial agent dates back to the 1800s. Silver systems release positively charged silver ions (Ag+), when in aqueous media, that disrupts negatively charged surfaces of bacterial membranes, thus resulting in bacterial death. Its antimicrobial utility is not ...

Environmental fate of two sulfonamide antimicrobial agents in soil.

PubMed

Accinelli, Cesare; Koskinen, William C; Becker, Joanna M; Sadowsky, Michael J

2007-04-04

Veterinary antimicrobial agents have been detected in a number of environmental samples, including agricultural soils. In this study, we investigated the persistence and sorption of the sulfonamides sulfamethazine (SMZ) and sulfachloropyridine (SCP) in soil and their potential effects on soil microorganisms. The sulfonamides dissipated more rapidly from the silt loam soil as compared to the sandy soil. Average half-lives of SMZ and SPC among the two soils were 18.6 and 21.3 days, respectively. The presence of liquid swine slurry (5% v/w) decreased sulfonamide persistence in the silt loam soil. The lower persistence of the antimicrobials in liquid swine slurry-amended soil was likely due to higher microbial activity, as compared to unamended soil, and/or to the greater bioavailability of the sulfonamides to degrading microorganisms, as estimated by sorption isotherms. Concentrations of SMZ and SPC up to 100 microg g-1 had no effect on antimicrobial degradation rates and soil microorganisms. These studies suggest that higher sulfonamide concentrations would be necessary to affect the main processes controlling their environmental fates in soil, but at the concentrations normally found in the environment, there would be little or no effects.

Species of Genus Ganoderma (Agaricomycetes) Fermentation Broth: A Novel Antioxidant and Antimicrobial Agent.

PubMed

Cilerdzic, Jasmina; Kosanic, Marijana; Stajić, Mirjana; Vukojevic, Jelena; Ranković, Branislav

2016-01-01

The bioactivity of Ganoderma lucidum basidiocarps has been well documented, but there are no data on the medicinal properties of its submerged cultivation broth nor on the other species of the genus Ganoderma. Thus the aim of this study was to test the potential antimicrobial and antioxidant activity of fermentation broth obtained after submerged cultivation of G. applanatum, G. carnosum, and G. lucidum. DPPH· scavenging ability, total phenols, and flavonoid contents were measured to determine the antioxidative potential of Ganoderma spp. fermentation filtrates, whereas their antimicrobial potential was studied using the microdilution method. DPPH· scavenging activity of G. lucidum fermentation filtrates was significantly higher than that of G. applanatum and G. carnosum, with the maximum (39.67%) obtained from strain BEOFB 432. This filtrate also contained the highest concentrations of phenols (134.89 μg gallic acid equivalents/mL) and flavonoids (42.20 μg quercetin equivalent/mL). High correlations between the activity and phenol content in the extracts showed that these compounds were active components of the antioxidative activity. G. lucidum strain BEOFB 432 was the most effective antibacterial agent, whereas strain BEOFB 434 has proven to be the most effective antifungal agent. The study showed that Ganoderma spp. fermentation filtrates are novel potent antioxidative and antimicrobial agents that could be obtained more quickly and cheaper than basidiocarps.

Antimicrobial peptides: Possible anti-infective agents.

PubMed

Lakshmaiah Narayana, Jayaram; Chen, Jyh-Yih

2015-10-01

Multidrug-resistant bacterial, fungal, viral, and parasitic infections are major health threats. The Infectious Diseases Society of America has expressed concern on the decrease of pharmaceutical companies working on antibiotic research and development. However, small companies, along with academic research institutes, are stepping forward to develop novel therapeutic methods to overcome the present healthcare situation. Among the leading alternatives to current drugs are antimicrobial peptides (AMPs), which are abundantly distributed in nature. AMPs exhibit broad-spectrum activity against a wide variety of bacteria, fungi, viruses, and parasites, and even cancerous cells. They also show potential immunomodulatory properties, and are highly responsive to infectious agents and innate immuno-stimulatory molecules. In recent years, many AMPs have undergone or are undergoing clinical development, and a few are commercially available for topical and other applications. In this review, we outline selected anion and cationic AMPs which are at various stages of development, from preliminary analysis to clinical drug development. Moreover, we also consider current production methods and delivery tools for AMPs, which must be improved for the effective use of these agents. Copyright © 2015 Elsevier Inc. All rights reserved.

Understanding the Mechanism of Bacterial Biofilms Resistance to Antimicrobial Agents

PubMed Central

Singh, Shriti; Singh, Santosh Kumar; Chowdhury, Indrajit; Singh, Rajesh

2017-01-01

A biofilm is a group of microorganisms, that causes health problems for the patients with indwelling medical devices via attachment of cells to the surface matrix. It increases the resistance of a microorganism for antimicrobial agents and developed the human infection. Current strategies are removed or prevent the microbial colonies from the medical devices, which are attached to the surfaces. This will improve the clinical outcomes in favor of the patients suffering from serious infectious diseases. Moreover, the identification and inhibition of genes, which have the major role in biofilm formation, could be the effective approach for health care systems. In a current review article, we are highlighting the biofilm matrix and molecular mechanism of antimicrobial resistance in bacterial biofilms. PMID:28553416

[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.

Antimicrobial agent-free hybrid cationic starch/sodium alginate polyelectrolyte films for food packaging materials.

PubMed

Şen, Ferhat; Uzunsoy, İrem; Baştürk, Emre; Kahraman, Memet Vezir

2017-08-15

This study aimed to develop polyelectrolyte structured antimicrobial food packaging materials that do not contain any antimicrobial agents. Cationic starch was synthesized and characterized by FT-IR spectroscopy and 1 H NMR spectroscopy. Its nitrogen content was determined by Kjeldahl method. Polyelectrolyte structured antimicrobial food packaging materials were prepared using starch, cationic starch and sodium alginate. Antimicrobial activity of materials was defined by inhibition zone method (disc diffusion method). Thermal stability of samples was evaluated by TGA and DSC. Hydrophobicity of samples was determined by contact angle measurements. Surface morphology of samples was investigated by SEM. Moreover, gel contents of samples were determined. The obtained results prove that produced food packaging materials have good thermal, antimicrobial and surface properties, and they can be used as food packaging material in many industries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Occurrence of Salmonella spp. in broiler chicken carcasses and their susceptibility to antimicrobial agents

PubMed Central

Duarte, Dalila Angélica Moliterno; Ribeiro, Aldemir Reginato; Vasconcelos, Ana Mércia Mendes; Santos, Sylnei Barros; Silva, Juliana Vital Domingos; de Andrade, Patrícia Lúcia Arruda; de Arruda Falcão, Lúcia Sadae Pereira da Costa

2009-01-01

The present study was carried out to evaluate the occurrence of Salmonellae in broiler chicken carcasses and to determine the antimicrobial resistance profile of the isolated strains. Twenty-five out of the 260 broiler chicken carcasses samples (9.6%) were positive for Salmonella. S. Enteritidis was the most frequent serovar. Nineteen Salmonella isolates were tested for antimicrobial resistance, and the results indicated that 94.7% were resistant to at least one antimicrobial agent. Resistance to streptomycin (73.7%), nitrofurantoin (52.3%), tetracycline (31.6%), and nalidixic acid (21%) were the prevalent amongst Salmonella strains tested. PMID:24031401

Sales of veterinary antimicrobial agents for therapeutic use in food-producing animal species in Japan between 2005 and 2010.

PubMed

Hosoi, Y; Asai, T; Koike, R; Tsuyuki, M; Sugiura, K

2014-12-01

The use of veterinary antimicrobial agents in animals can result in the emergence and selection of resistant bacteria in food-producing animals. This study elucidated the use of veterinary antimicrobial agents in Japan in terms of milligrams of active ingredient sold per kilogram of biomass between 2005 and 2010. Data on sales of antimicrobial agents and on the biomass of the target animal species were compiled from statistics published bythe Japanese Ministry of Agriculture, Forestry and Fisheries. The quantities of antimicrobials used varied between animal species: the highest usage was observed in pigs (392 to 423 mg/ kg), followed by beef cattle (45 to 67 mg/kg), broiler chickens (44 to 63 mg/kg) and dairy cattle (33 to 49 mg/kg). For the animal species combined, usage of third- and fourth-generation cefalosporins, fluoroquinolones and macrolides ranged from 0.10 to 0.14 mg/kg biomass, 1.1 to 1.3 mg/kg biomass and 7.8 to 10.6 mg/kg biomass, respectively.

Light activated compounds as antimicrobial agents - patently obvious?

PubMed

Phoenix, D A; Harris, F

2006-06-01

Microbial pathogens with resistance to conventional drugs are a problem of global proportions and may be viral such as HIV, bacterial as in the case of MRSA or eukaryotic as seen with the malarial parasite Plasmodium falciparum. In response, photodynamic antimicrobial chemotherapy (PACT) has been developed, which is the delivery of a non-toxic photosensitiser (PS) to the site of a microbial infection. When taken up by the pathogen, illumination of the PS by light at an appropriate wavelength can lead to inactivation of the pathogen through the production of highly reactive free radical species, which induce oxidative damage to lipid, proteins and DNA / RNA, and / or adduct formation between the PS and these microbial biomolecules. Here the photochemical and photophysical steps underlying PS antimicrobial action along with the desirable electronic and physiochemical properties of PS are briefly reviewed. The therapeutic uses of PS are then illustrated with reference to a number that have featured in recent patents, including: The induction of endogenous PS by aminolevulinic acid; phenothiazinium based PS, which are the most studied of PACT agents, psoralens and organorhodium complexes.

Antibiofilm agents: A new perspective for antimicrobial strategy.

PubMed

Li, Xi-Hui; Lee, Joon-Hee

2017-10-01

Biofilms are complex microbial architectures that attach to surfaces and encase microorganisms in a matrix composed of self-produced hydrated extracellular polymeric substances (EPSs). In biofilms, microorganisms become much more resistant to antimicrobial treatments, harsh environmental conditions, and host immunity. Biofilm formation by microbial pathogens greatly enhances survival in hosts and causes chronic infections that result in persistent inflammation and tissue damages. Currently, it is believed over 80% of chronic infectious diseases are mediated by biofilms, and it is known that conventional antibiotic medications are inadequate at eradicating these biofilm-mediated infections. This situation demands new strategies for biofilm-associated infections, and currently, researchers focus on the development of antibiofilm agents that are specific to biofilms, but are nontoxic, because it is believed that this prevents the development of drug resistance. Here, we review the most promising antibiofilm agents undergoing intensive research and development.

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).

Synthesis of Some Benzofuran Derivatives Containing Pyrimidine Moiety as Potent Antimicrobial Agents.

PubMed

Venkatesh, Talavara; Bodke, Yadav Dasharathrao; Joy, Muthipeedika Nibin; Dhananjaya, Bhadrapura Lakkappa; Venkataraman, Sivaramakrishnan

2018-01-01

In this investigation, the synthesis of 2-substituted pyrimidines by the reaction of benzofuran chalcones (3a-d) with urea, thiourea and guanidine hydrochloride was reported. The structures of title compounds (4a-d), (5a-d) and (6a-d) were established on the basis of analytical and spectral data. The synthesized compounds were screened for antimicrobial activity and molecular docking studies. Some of the compounds displayed excellent antimicrobial activity. The molecular docking analysis revealed that compounds 5a and 5c with the lowest binding energy in comparison to others suggesting its potential as best inhibitor of GluN-6-P. Consequently, it is confirmed from the above analysis that the compounds 5a and 5c might serve as a useful backbone scaffold for rational design, adaptation and investigation of more active analogs as potential broad spectrum antimicrobial agents.

General Principles of Antimicrobial Therapy

PubMed Central

Leekha, Surbhi; Terrell, Christine L.; Edson, Randall S.

2011-01-01

Antimicrobial agents are some of the most widely, and often injudiciously, used therapeutic drugs worldwide. Important considerations when prescribing antimicrobial therapy include obtaining an accurate diagnosis of infection; understanding the difference between empiric and definitive therapy; identifying opportunities to switch to narrow-spectrum, cost-effective oral agents for the shortest duration necessary; understanding drug characteristics that are peculiar to antimicrobial agents (such as pharmacodynamics and efficacy at the site of infection); accounting for host characteristics that influence antimicrobial activity; and in turn, recognizing the adverse effects of antimicrobial agents on the host. It is also important to understand the importance of antimicrobial stewardship, to know when to consult infectious disease specialists for guidance, and to be able to identify situations when antimicrobial therapy is not needed. By following these general principles, all practicing physicians should be able to use antimicrobial agents in a responsible manner that benefits both the individual patient and the community. PMID:21282489

General principles of antimicrobial therapy.

PubMed

Leekha, Surbhi; Terrell, Christine L; Edson, Randall S

2011-02-01

Antimicrobial agents are some of the most widely, and often injudiciously, used therapeutic drugs worldwide. Important considerations when prescribing antimicrobial therapy include obtaining an accurate diagnosis of infection; understanding the difference between empiric and definitive therapy; identifying opportunities to switch to narrow-spectrum, cost-effective oral agents for the shortest duration necessary; understanding drug characteristics that are peculiar to antimicrobial agents (such as pharmacodynamics and efficacy at the site of infection); accounting for host characteristics that influence antimicrobial activity; and in turn, recognizing the adverse effects of antimicrobial agents on the host. It is also important to understand the importance of antimicrobial stewardship, to know when to consult infectious disease specialists for guidance, and to be able to identify situations when antimicrobial therapy is not needed. By following these general principles, all practicing physicians should be able to use antimicrobial agents in a responsible manner that benefits both the individual patient and the community.

Repurposing Auranofin, Ebselen, and PX-12 as Antimicrobial Agents Targeting the Thioredoxin System

PubMed Central

May, Holly C.; Yu, Jieh-Juen; Guentzel, M. N.; Chambers, James P.; Cap, Andrew P.; Arulanandam, Bernard P.

2018-01-01

As microbial resistance to drugs continues to rise at an alarming rate, finding new ways to combat pathogens is an issue of utmost importance. Development of novel and specific antimicrobial drugs is a time-consuming and expensive process. However, the re-purposing of previously tested and/or approved drugs could be a feasible way to circumvent this long and costly process. In this review, we evaluate the U.S. Food and Drug Administration tested drugs auranofin, ebselen, and PX-12 as antimicrobial agents targeting the thioredoxin system. These drugs have been shown to act on bacterial, fungal, protozoan, and helminth pathogens without significant toxicity to the host. We propose that the thioredoxin system could serve as a useful therapeutic target with broad spectrum antimicrobial activity. PMID:29556223

[Recommendations for selecting antimicrobial agents for in vitro susceptibility studies using automatic and semiautomatic systems].

PubMed

Cantón, Rafael; Alós, Juan Ignacio; Baquero, Fernando; Calvo, Jorge; Campos, José; Castillo, Javier; Cercenado, Emilia; Domínguez, M Angeles; Liñares, Josefina; López-Cerezo, Lorena; Marco, Francesc; Mirelis, Beatriz; Morosini, María-Isabel; Navarro, Ferran; Oliver, Antonio; Pérez-Trallero, Emilio; Torres, Carmen; Martínez-Martínez, Luis

2007-01-01

The number of clinical microbiology laboratories that have incorporated automatic susceptibility testing devices has increased in recent years. The majority of these systems determine MIC values using microdilution panels or specific cards, with grouping into clinical categories (susceptible, intermediate or resistant) and incorporate expert systems to infer resistance mechanisms. This document presents the recommendations of a group of experts designated by Grupo de Estudio de los Mecanismos de Acción y Resistencia a los Antimicrobianos (GEMARA, Study group on mechanisms of action and resistance to antimicrobial agents) and Mesa Española de Normalización de la Sensibilidad y Resistencia a los Antimicrobianos (MENSURA, Spanish Group for Normalizing Antimicrobial Susceptibility and Antimicrobial Resistance), with the aim of including antimicrobial agents and selecting concentrations for the susceptibility testing panels of automatic systems. The following have been defined: various antimicrobial categories (A: must be included in the study panel; B: inclusion is recommended; and C: inclusion is secondary, but may facilitate interpretative reading of the antibiogram) and groups (0: not used in therapeutics but may facilitate the detection of resistance mechanisms; 1: must be studied and always reported; 2: must be studied and selectively reported; 3: must be studied and reported at a second level; and 4: should be studied in urinary tract pathogens isolated in urine and other specimens). Recommended antimicrobial concentrations are adapted from the breakpoints established by EUCAST, CLSI and MENSURA. This approach will lead to more accurate susceptibility testing results with better detection of resistance mechanisms, and allowing to reach the clinical goal of the antibiogram.

Combination Antimicrobial Nanocomposite Materials for Neutralization of Biological Threat Agents (PREPRINT)

DTIC Science & Technology

2008-09-01

AFRL-RX-TY-TP-2008-4601 PREPRINT COMBINATION ANTIMICROBIAL NANOCOMPOSITE MATERIALS FOR NEUTRALIZATION OF BIOLOGICAL THREAT AGENTS...AIRBASE TECHNOLOGIES DIVISION MATERIALS AND MANUFACTURING DIRECTORATE AIR FORCE RESEARCH LABORATORY AIR FORCE MATERIEL COMMAND 139 BARNES DRIVE, SUITE 2...a composite material that combines the protein and inorganic components. The process can be mimicked in vitro to some degree, providing methods for

Tolerance of dormant and active cells in Pseudomonas aeruginosa PA01 biofilm to antimicrobial agents.

PubMed

Kim, Jaeeun; Hahn, Ji-Sook; Franklin, Michael J; Stewart, Philip S; Yoon, Jeyong

2009-01-01

The aim of the study was to determine the susceptibility of active and dormant cell populations from Pseudomonas aeruginosa biofilms to non-antibiotic antimicrobial agents such as chlorine, hydrogen peroxide and silver ions in comparison with antibiotics. Active cells in colony biofilm were differentially labelled by induction of a green fluorescent protein (GFP). Active and dormant cells were sorted in phosphate buffered solution by flow cytometry. Reductions in viability were determined with plate counts. The spatial pattern of metabolic activity in colony biofilm was verified, and the active and dormant cells were successfully sorted according to the GFP intensity. Active cells had bigger cell size and higher intracellular density than dormant cells. While dormant cells were more tolerant to tobramycin and silver ions, active cells were more tolerant to chlorine. Metabolically active cells contain denser intracellular components that can react with highly reactive oxidants such as chlorine, thereby reducing the available concentrations of chlorine. In contrast, the concentrations of silver ions and hydrogen peroxide were constant during treatment. Aerobically grown stationary cells were significantly more tolerant to chlorine unlike other antimicrobial agents. Chlorine was more effective in inactivation of metabolically inactive dormant cells and also more effective under anaerobic conditions. The high oxidative reactivity and rapid decay of chlorine might influence the different antimicrobial actions of chlorine compared with antibiotics. This study contributes to understanding the effects of dormancy and the presence of oxygen on the susceptibility of P. aeruginosa biofilm to a wide range of antimicrobial agents.

Neuropsychiatric Effects of Antimicrobial Agents.

PubMed

Zareifopoulos, Nicholas; Panayiotakopoulos, George

2017-05-01

Antimicrobial drugs used in clinical practice are selected on the basis of their selective toxicity against bacterial cells. However, all exhibit multiple offsite interactions with eukaryotic cell structures, resulting in adverse reactions during antimicrobial pharmacotherapy. A multitude of these side effects involve the nervous system as antimicrobials at clinically relevant concentrations seem to interact with many of the same molecules usually implicated in the action of psychotropic drugs. The importance of such events cannot be overstated, as the misdiagnosis of an adverse drug reaction as a symptom of a primary psychiatric or neurological disorder entails great suffering for the patient affected as well as significant costs for the healthcare system. The neuropsychiatric effects of antimicrobial drugs are extensively documented in the literature. A number of antimicrobial drugs have the potential to exert CNS effects and many are associated with stimulant, psychotomimetic and epileptogenic properties, mediated by GABA antagonism (beta-lactams, quinolones and clarithromycin), NMDA agonism (D-cycloserine, aminoglycosides, and perhaps quinolones), MAO inhibition (linezolid, metronidazole and isoniazid weakly) as well as more exotic mechanisms, as in the case of trimethoprim, isoniazid, ethambutol, rifampicin and the tetracyclines. While those effects are generally undesirable, they may also under certain circumstances be beneficial, and further research is warranted in that direction.

Aqueous Zinc Compounds as Residual Antimicrobial Agents for Textiles.

PubMed

Holt, Brandon Alexander; Gregory, Shawn Alan; Sulchek, Todd; Yee, Shannon; Losego, Mark D

2018-03-07

Textiles, especially those worn by patients and medical professionals, serve as vectors for proliferating pathogens. Upstream manufacturing techniques and end-user practices, such as transition-metal embedment in textile fibers or alcohol-based disinfectants, can mitigate pathogen growth, but both techniques have their shortcomings. Fiber embedment requires complete replacement of all fabrics in a facility, and the effects of embedded nanoparticles on human health remain unknown. Alcohol-based, end-user disinfectants are short-lived because they quickly volatilize. In this work, common zinc salts are explored as an end-user residual antimicrobial agent. Zinc salts show cost-effective and long-lasting antimicrobial efficacy when solution-deposited on common textiles, such as nylon, polyester, and cotton. Unlike common alcohol-based disinfectants, these zinc salt-treated textiles mitigate microbial growth for more than 30 days and withstand commercial drying. Polyester fabrics treated with ZnO and ZnCl 2 were further explored because of their commercial ubiquity and likelihood for rapid commercialization. ZnCl 2 -treated textiles were found to retain their antimicrobial coating through abrasive testing, whereas ZnO-treated textiles did not. Scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry analyses suggest that ZnCl 2 likely hydrolyzes and reacts with portions of the polyester fiber, chemically attaching to the fiber, whereas colloidal ZnO simply sediments and binds with weaker physical interactions.

Antimicrobial Polymer

DOEpatents

McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

2004-09-28

A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

Strategies for transformation of naturally-occurring amphibian antimicrobial peptides into therapeutically valuable anti-infective agents.

PubMed

Conlon, J Michael; Al-Ghaferi, Nadia; Abraham, Bency; Leprince, Jérôme

2007-08-01

The emergence of strains of pathogenic microorganisms with resistance to commonly used antibiotics has necessitated a search for novel types of antimicrobial agents. Many frog species produce amphipathic alpha-helical peptides with broad spectrum antimicrobial activity in the skin but their therapeutic potential is limited by varying degrees of cytolytic activity towards eukaryotic cells. Methods for development of such peptides into anti-infective drugs are illustrated by the example of temporin-1DRa (HFLGTLVNLAK KIL.NH(2)). Studies with model alpha-helical peptides have shown that increase in cationicity promotes antimicrobial activity whereas increases in hydrophobicity, helicity and amphipathicity promote hemolytic activity and loss of selectivity for microorganisms. Analogs of temporin-1DRa in which each amino acid is replaced by L-lysine and D-lysine were synthesized and their cytolytic activities tested against a range of microorganisms and human erythrocytes. Small changes in structure produced marked changes in conformation, as determined by retention time on reversed-phase HPLC, and in biological activity. However, peptides containing the substitutions (Val(7) -->L-Lys), (Thr(5)-->D-Lys) and (Asn(8)-->D-Lys) retained the high solubility and potent, broad spectrum antimicrobial activity of the naturally occurring peptide but were appreciably (up to 10-fold) less hemolytic. In contrast, analogs in which Leu(9) and Ile(13) were replaced by the more hydrophobic cyclohexylglycine residue showed slightly increased antimicrobial potencies (up to 2-fold) but a 4-fold increase in hemolytic activity. The data suggest a strategy of selective increases in cationicity concomitant with decreases in helicity and hydrophobicity in the transformation of naturally-occurring antimicrobial peptides into non-toxic therapeutic agents.

Synthesis and Evaluation of Ester Derivatives of 10-Hydroxycanthin-6-one as Potential Antimicrobial Agents.

PubMed

Zhao, Fei; Dai, Jiang-Kun; Liu, Dan; Wang, Shi-Jun; Wang, Jun-Ru

2016-03-21

As part of our continuing research on canthin-6-one antimicrobial agents, a new series of ester derivatives of 10-hydroxycanthin-6-one were synthesized using a simple and effective synthetic route. The structure of each compound was characterized by NMR, ESI-MS, FT-IR, UV, and elemental analysis. The antimicrobial activity of these compounds against three phytopathogenic fungi (Alternaria solani, Fusarium graminearum, and Fusarium solani) and four bacteria (Bacillus cereus, Bacillus subtilis, Ralstonia solanacearum, and Pseudomonas syringae) were evaluated using the mycelium linear growth rate method and micro-broth dilution method, respectively. The structure-activity relationship is discussed. Of the tested compounds, 4 and 7s displayed significant antifungal activity against F. graminearum, with inhibition rates of 100% at a concentration of 50 μg/mL. Compounds 5, 7s, and 7t showed the best inhibitory activity against all the tested bacteria, with minimum inhibitory concentrations (MICs) between 3.91 and 31.25 μg/mL. Thus, 7s emerged as a promising lead compound for the development of novel canthine-6-one antimicrobial agents.

Gold nanoparticles synthesized by Brassica oleracea (Broccoli) acting as antimicrobial agents against human pathogenic bacteria and fungi

NASA Astrophysics Data System (ADS)

Piruthiviraj, Prakash; Margret, Anita; Krishnamurthy, Poornima Priyadharsani

2016-04-01

Production of antimicrobial agents through the synthesis of gold nanoparticles using green technology has been extensively made consistent by various researchers; yet, this study uses the flower bud's aqueous extracts of Brassica oleracea (Broccoli) as a reducing agent for chloroauric acid (1 mM). After 30 min of incubation, synthesis of gold nanoparticles (AuNps) was observed by a change in extract color from pale yellow to purple color. Synthesis of AuNps was confirmed in UV-visible spectroscopy at the range of approximately 560 nm. The SEM analysis showed the average nanoparticles size of 12-22 nm. The antimicrobial activity of AuNps was analyzed by subjecting it to human pathogenic bacteria (Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumonia) and fungi (Aspergillus flavus, Aspergillus niger and Candida albicans) using disc diffusion method. The broccoli-synthesized AuNps showed the efficient antibacterial and antifungal activity of above-mentioned microbes. It was confirmed that AuNps have the best antimicrobial agent compared to the standard antibiotics (Gentamicin and Fluconazole). When the concentrations of AuNps were increased (10, 25, and 50 µg/ml), the sensitivity zone also increased for all the tested microbes. The synthesized AuNps are capable of rendering high antimicrobial efficacy and, hence, have a great potential in the preparation of drugs used against major bacterial and fungal diseases in humans.

Characterization of Antimicrobial Agent Loaded Eudragit RS Solvent Exchange-Induced In Situ Forming Gels for Periodontitis Treatment.

PubMed

Phaechamud, Thawatchai; Jantadee, Takron; Mahadlek, Jongjan; Charoensuksai, Purin; Pichayakorn, Wiwat

2017-02-01

Eudragit RS (ERS), a quaternary polyacrylate positively charged polymer, exhibits a very low permeability and swells in aqueous media independently of pH without dissolving. Owing to its high solubility in N-methyl pyrrolidone (NMP), it was interesting to apply as polymer matrix for solvent-exchanged in situ forming gel. The aim of this research was to prepare in situ forming gels from ERS to deliver the antimicrobial agents (doxycycline hyclate, metronidazole, and benzoyl peroxide) for periodontitis treatment. They were evaluated for viscosity and rheology, gel formation, syringeability, drug release, and antimicrobial activities. The solvent exchange between NMP and an external aqueous simulated gingival crevicular fluid stimulated the dissolved ERS transforming into the opaque rigid gel. Antimicrobial agent loaded ERS systems exhibited Newtonian flow with acceptable syringeability. The higher-loaded ERS promoted the more prolongation of drug release because of the retardation of water diffusion into the precipitated matrix. Antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans, and Porphyromonas gingivalis depended on type of drugs and test microorganisms. Doxycycline hyclate loaded ERS systems showed these activities greater than the others; however, all of them could inhibit all test microorganisms. Thus, the solvent exchange-induced in situ forming gels comprising ERS-antimicrobial drugs exhibited potential use as localized delivery systems for periodontitis treatment.

Prevalence of multi-antimicrobial-agent resistant, shiga toxin and enterotoxin producing Escherichia coli in surface waters of river Ganga.

PubMed

Ram, Siya; Vajpayee, Poornima; Shanker, Rishi

2007-11-01

The consumption of polluted surface water for domestic and recreational purposes by large populations in developing nations is a major cause of diarrheal disease related mortality. The river Ganga and its tributaries meet 40% of the water requirement for drinking and irrigation in India. In this study, Escherichia coli isolates (n=75) of the river Ganga water were investigated for resistance to antimicrobial agents (n=15) and virulence genes specific to shiga toxin (STEC) and enterotoxin producing E. coli (ETEC). E. coli isolates from the river Ganga water exhibit resistance to multiple antimicrobial agents. The distribution of antimicrobial agent resistance in E. colivaries significantly (chi2: 81.28 at df = 24, p < 0.001) between the sites. Both stx1 and stx2 genes were present in 82.3% of STEC (n=17) while remaining isolates possess either stxl (11.8%) or stx2 (5.9%). The presence of eaeA, hlyA, and chuA genes was observed in 70.6, 88.2, and 58.8% of STEC, respectively. Both LT1 and ST1 genes were positive in 66.7% of ETEC (n=15) while 33.3% of isolates harbor only LT1 gene. The prevalence of multi-antimicrobial-agent resistant E. coli in the river Ganga water poses increased risk of infections in the human population.

Resistance to antimicrobial agents among Salmonella isolates recovered from layer farms and eggs in the Caribbean region.

PubMed

Adesiyun, Abiodun; Webb, Lloyd; Musai, Lisa; Louison, Bowen; Joseph, George; Stewart-Johnson, Alva; Samlal, Sannandan; Rodrigo, Shelly

2014-12-01

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries, the frequency of resistance to antimicrobial agents was significantly different for ampicillin (P = 0.001) and SXT (P = 0.032). A total of 83 (98.8%) of the 84 isolates exhibited 39 multidrug resistance patterns. Farm size significantly (P = 0.032) affected the frequency of resistance to kanamycin across the countries. Overall, among the 14 serotypes of Salmonella tested, significant (P < 0.05) differences in frequency of resistance were detected to kanamycin, ampicillin, and SXT. Results suggest that the relatively high frequency of resistance to six of the antimicrobial agents (erythromycin, streptomycin, gentamycin, kanamycin, ampicillin, and tetracycline) tested and the multidrug resistance detected may pose prophylactic and therapeutic concerns for chicken layer farms in the three countries studied.

Determining Multiple Responses of Pseudomonas aeruginosa PAO1 to an Antimicrobial Agent, Free Nitrous Acid.

PubMed

Gao, Shu-Hong; Fan, Lu; Peng, Lai; Guo, Jianhua; Agulló-Barceló, Míriam; Yuan, Zhiguo; Bond, Philip L

2016-05-17

Free nitrous acid (FNA) has recently been demonstrated as an antimicrobial agent on a range of micro-organisms, especially in wastewater-treatment systems. However, the antimicrobial mechanism of FNA is largely unknown. Here, we report that the antimicrobial effects of FNA are multitargeted. The response of a model denitrifier, Pseudomnas aeruginosa PAO1 (PAO1), common in wastewater treatment, was investigated in the absence and presence of inhibitory level of FNA (0.1 mg N/L) under anaerobic denitrifying conditions. This was achieved through coupling gene expression analysis, by RNA sequencing, and with a suite of physiological analyses. Various transcripts exhibited significant changes in abundance in the presence of FNA. Respiration was likely inhibited because denitrification activity was severely depleted, and decreased transcript levels of most denitrification genes occurred. As a consequence, the tricarboxylic acid (TCA) cycle was inhibited due to the lowered cellular redox state in the FNA-exposed cultures. Meanwhile, during FNA exposure, PAO1 rerouted its carbon metabolic pathway from the TCA cycle to pyruvate fermentation with acetate as the end product as a possible survival mechanism. Additionally, protein synthesis was significantly decreased, and ribosome preservation was evident. These findings improve our understanding of PAO1 in response to FNA and contribute toward the potential application for use of FNA as an antimicrobial agent.

Component Release and Mechanical Properties of Endodontic Sealers following Incorporation of Antimicrobial Agents.

PubMed

Gjorgievska, Elizabeta S; Nicholson, John W; Coleman, Nichola J; Booth, Samantha; Dimkov, Aleksandar; Hurt, Andrew

2017-01-01

Root canal sealers with antimicrobial activity are highly beneficial; therefore, their antimicrobial properties could be improved by incorporation of antimicrobial agents. In the present study, the release of the quaternary ammonium compounds from endodontic sealers admixed with either benzalkonium chloride (BC) or cetylpyridinium chloride (CPC) at loadings of 2% wt was monitored. The effect of these additives on the compressive strengths and their release from the sealers was determined after 1 and 4 weeks. All of the materials studied were found to be capable of releasing antimicrobial additive in useful quantities. The release of CPC occurred to a statistically significant greater extent than BC for all materials. The addition of both BC and CPC generally decreased the compressive strength of all the endodontic sealers, with the exception of CPC in AH Plus, where the compressive strength was significantly increased. This suggests that, for these endodontic sealers, the antimicrobial additives alter the setting chemistry. AH Plus is an epoxy-based material cured with an amine, and in this case the increase in compressive strength with CPC is attributed to an enhanced cure reaction with this system. In all other cases, the additive inhibited the cure reaction to a greater or lesser extent.

Component Release and Mechanical Properties of Endodontic Sealers following Incorporation of Antimicrobial Agents

PubMed Central

Nicholson, John W.; Coleman, Nichola J.; Booth, Samantha; Dimkov, Aleksandar

2017-01-01

Root canal sealers with antimicrobial activity are highly beneficial; therefore, their antimicrobial properties could be improved by incorporation of antimicrobial agents. In the present study, the release of the quaternary ammonium compounds from endodontic sealers admixed with either benzalkonium chloride (BC) or cetylpyridinium chloride (CPC) at loadings of 2% wt was monitored. The effect of these additives on the compressive strengths and their release from the sealers was determined after 1 and 4 weeks. All of the materials studied were found to be capable of releasing antimicrobial additive in useful quantities. The release of CPC occurred to a statistically significant greater extent than BC for all materials. The addition of both BC and CPC generally decreased the compressive strength of all the endodontic sealers, with the exception of CPC in AH Plus, where the compressive strength was significantly increased. This suggests that, for these endodontic sealers, the antimicrobial additives alter the setting chemistry. AH Plus is an epoxy-based material cured with an amine, and in this case the increase in compressive strength with CPC is attributed to an enhanced cure reaction with this system. In all other cases, the additive inhibited the cure reaction to a greater or lesser extent. PMID:28620615

Isolation, Purification and Characterization of Antimicrobial Agent Antagonistic to Escherichia coli ATCC 10536 Produced by Bacillus pumilus SAFR-032 Isolated from the Soil of Unaizah, Al Qassim Province of Saudi Arabia.

PubMed

S Alanazi, Abdurrahman; Qureshi, Kamal Ahmad; Elhassan, Gamal Osman; I El-Agamy, Elsayed

Escherichia coli is one of the most common pathogenic bacteria, which cause urinary tract infections in infants as well as in adult human beings. Due to the emergence of antibiotic resistance in E. coli, there is a great demand of new antimicrobial agent for the treatment of infections caused by such E. coli. This study aims to isolate, identify and characterize the native soil-bacterial strains predominate in the soil of Unaizah city, which produce antimicrobial agent antagonistic to E. coli ATCC 10536, followed by isolation, purification and characterization of antimicrobial agent. Pour plate, spread plate and 16S rRNA sequence analysis methods were followed for the isolation and identification of soil bacteria. Ammonium sulphate and dialysis (MWCO-8 KD) methods were followed for the isolation and partial purification of antimicrobial agent from the cell free broths. The characterization of antimicrobial agent was carried out by determining the minimum inhibitory concentration and effects of temperature and pH on the antimicrobial stability. Out of the twenty five soil samples, only one soil-bacterial strain was found to produce antimicrobial agent antagonistic to E. coli ATCC 10536. The isolated soil bacterium was identified as Bacillus pumilus SAFR-032. The soil isolate was characterized and results suggest that 30°C temperature and pH 7.0 were the optimum growth parameters and soybean casein digest broth was the best fermentation medium, whereas the highest production of antimicrobial agent was at 35°C temperature, pH 7.0, shaking at 150-220 rpm and at 60th h of incubation. The maximum yield of antimicrobial agent was obtained at 60% of (NH 4) 2SO 4. The results of characterization of antimicrobial agent suggest that the maximum and minimum antimicrobial activities were at pH 3.0 and 8.0, respectively, whereas antimicrobial activity was unaffected by temperature. The antimicrobial agent was highly stable at varying range of temperature 50-120°C. Minimum

Engineered Chimeric Peptides as Antimicrobial Surface Coating Agents toward Infection-Free Implants

PubMed Central

Yazici, Hilal; O'Neill, Mary B.; Kacar, Turgay; Wilson, Brandon R.; Oren, E. Emre; Sarikaya, Mehmet; Tamerler, Candan

2016-01-01

Prevention of bacterial colonization and consequent biofilm formation remains a major challenge in implantable medical devices. Implant-associated infections are not only a major cause of implant failures but also their conventional treatment with antibiotics brings further complications due to the escalation in multidrug resistance to a variety of bacterial species. Owing to their unique properties, antimicrobial peptides (AMPs) have gained significant attention as effective agents to combat colonization of microorganisms. These peptides have been shown to exhibit a wide spectrum of activities with specificity to a target cell while having a low tendency for developing bacterial resistance. Engineering biomaterial surfaces that feature AMP properties, therefore, offer a promising approach to prevent implant infections. Here, we engineered a chimeric peptide with bifunctionality that both forms a robust solid-surface coating while presenting antimicrobial property. The individual domains of the chimeric peptides were evaluated for their solid-binding kinetics to titanium substrate as well as for their antimicrobial properties in solution. The antimicrobial efficacy of the chimeric peptide on the implant material was evaluated in vitro against infection by a variety of bacteria, including Streptococcus mutans, Staphylococcus. epidermidis, and Escherichia coli, which are commonly found in oral and orthopedic implant related surgeries. Our results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces below the detectable limit. Engineered chimeric peptides with freely displayed antimicrobial domains could be a potential solution for developing infection-free surfaces by engineering implant interfaces with highly reduced bacterial colonization property. PMID:26795060

Engineered Chimeric Peptides as Antimicrobial Surface Coating Agents toward Infection-Free Implants.

PubMed

Yazici, Hilal; O'Neill, Mary B; Kacar, Turgay; Wilson, Brandon R; Oren, E Emre; Sarikaya, Mehmet; Tamerler, Candan

2016-03-02

Prevention of bacterial colonization and consequent biofilm formation remains a major challenge in implantable medical devices. Implant-associated infections are not only a major cause of implant failures but also their conventional treatment with antibiotics brings further complications due to the escalation in multidrug resistance to a variety of bacterial species. Owing to their unique properties, antimicrobial peptides (AMPs) have gained significant attention as effective agents to combat colonization of microorganisms. These peptides have been shown to exhibit a wide spectrum of activities with specificity to a target cell while having a low tendency for developing bacterial resistance. Engineering biomaterial surfaces that feature AMP properties, therefore, offer a promising approach to prevent implant infections. Here, we engineered a chimeric peptide with bifunctionality that both forms a robust solid-surface coating while presenting antimicrobial property. The individual domains of the chimeric peptides were evaluated for their solid-binding kinetics to titanium substrate as well as for their antimicrobial properties in solution. The antimicrobial efficacy of the chimeric peptide on the implant material was evaluated in vitro against infection by a variety of bacteria, including Streptococcus mutans, Staphylococcus. epidermidis, and Escherichia coli, which are commonly found in oral and orthopedic implant related surgeries. Our results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces below the detectable limit. Engineered chimeric peptides with freely displayed antimicrobial domains could be a potential solution for developing infection-free surfaces by engineering implant interfaces with highly reduced bacterial colonization property.

Novel Penicillin Analogues as Potential Antimicrobial Agents; Design, Synthesis and Docking Studies.

PubMed

Ashraf, Zaman; Bais, Abdul; Manir, Md Maniruzzaman; Niazi, Umar

2015-01-01

A number of penicillin derivatives (4a-h) were synthesized by the condensation of 6-amino penicillinic acid (6-APA) with non-steroidal anti-inflammatory drugs as antimicrobial agents. In silico docking study of these analogues was performed against Penicillin Binding Protein (PDBID 1CEF) using AutoDock Tools 1.5.6 in order to investigate the antimicrobial data on structural basis. Penicillin binding proteins function as either transpeptidases or carboxypeptidases and in few cases demonstrate transglycosylase activity in bacteria. The excellent antibacterial potential was depicted by compounds 4c and 4e against Escherichia coli, Staphylococcus epidermidus and Staphylococcus aureus compared to the standard amoxicillin. The most potent penicillin derivative 4e exhibited same activity as standard amoxicillin against S. aureus. In the enzyme inhibitory assay the compound 4e inhibited E. coli MurC with an IC50 value of 12.5 μM. The docking scores of these compounds 4c and 4e also verified their greater antibacterial potential. The results verified the importance of side chain functionalities along with the presence of central penam nucleus. The binding affinities calculated from docking results expressed in the form of binding energies ranges from -7.8 to -9.2kcal/mol. The carboxylic group of penam nucleus in all these compounds is responsible for strong binding with receptor protein with the bond length ranges from 3.4 to 4.4 Ǻ. The results of present work ratify that derivatives 4c and 4e may serve as a structural template for the design and development of potent antimicrobial agents.

Novel Penicillin Analogues as Potential Antimicrobial Agents; Design, Synthesis and Docking Studies

PubMed Central

Ashraf, Zaman; Bais, Abdul; Manir, Md. Maniruzzaman; Niazi, Umar

2015-01-01

A number of penicillin derivatives (4a-h) were synthesized by the condensation of 6-amino penicillinic acid (6-APA) with non-steroidal anti-inflammatory drugs as antimicrobial agents. In silico docking study of these analogues was performed against Penicillin Binding Protein (PDBID 1CEF) using AutoDock Tools 1.5.6 in order to investigate the antimicrobial data on structural basis. Penicillin binding proteins function as either transpeptidases or carboxypeptidases and in few cases demonstrate transglycosylase activity in bacteria. The excellent antibacterial potential was depicted by compounds 4c and 4e against Escherichia coli, Staphylococcus epidermidus and Staphylococcus aureus compared to the standard amoxicillin. The most potent penicillin derivative 4e exhibited same activity as standard amoxicillin against S. aureus. In the enzyme inhibitory assay the compound 4e inhibited E. coli MurC with an IC50 value of 12.5 μM. The docking scores of these compounds 4c and 4e also verified their greater antibacterial potential. The results verified the importance of side chain functionalities along with the presence of central penam nucleus. The binding affinities calculated from docking results expressed in the form of binding energies ranges from -7.8 to -9.2kcal/mol. The carboxylic group of penam nucleus in all these compounds is responsible for strong binding with receptor protein with the bond length ranges from 3.4 to 4.4 Ǻ. The results of present work ratify that derivatives 4c and 4e may serve as a structural template for the design and development of potent antimicrobial agents. PMID:26267242

Nasal Carriage in Vietnamese Children of Streptococcus pneumoniae Resistant to Multiple Antimicrobial Agents

PubMed Central

Parry, Christopher M.; Diep, To Song; Wain, John; Hoa, Nguyen Thi Tuyet; Gainsborough, Mary; Nga, Diem; Davies, Catrin; Phu, Nguyen Hoan; Hien, Tran Tinh; White, Nicholas J.; Farrar, Jeremy J.

2000-01-01

Resistance to antimicrobial agents in Streptococcus pneumoniae is increasing rapidly in many Asian countries. There is little recent information concerning resistance levels in Vietnam. A prospective study of pneumococcal carriage in 911 urban and rural Vietnamese children, of whom 44% were nasal carriers, was performed. Carriage was more common in children <5 years old than in those ≥5 years old (192 of 389 [49.4%] versus 212 of 522 [40.6%]; P, 0.01). A total of 136 of 399 isolates (34%) had intermediate susceptibility to penicillin (MIC, 0.1 to 1 mg/liter), and 76 of 399 isolates (19%) showed resistance (MIC, >1.0 mg/liter). A total of 54 of 399 isolates (13%) had intermediate susceptibility to ceftriaxone, and 3 of 399 isolates (1%) were resistant. Penicillin resistance was 21.7 (95% confidence interval, 7.0 to 67.6) times more common in urban than in rural children (35 versus 2%; P, <0.001). More than 40% of isolates from urban children were also resistant to erythromycin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline. Penicillin resistance was independently associated with an urban location when the age of the child was controlled for. Multidrug resistance (resistance to three or more antimicrobial agent groups) was present in 32% of isolates overall but in 39% of isolates with intermediate susceptibility to penicillin and 86% of isolates with penicillin resistance. The predominant serotypes of the S. pneumoniae isolates were 19, 23, 14, 6, and 18. Almost half of the penicillin-resistant isolates serotyped were serotype 23, and these isolates were often multidrug resistant. This study suggests that resistance to penicillin and other antimicrobial agents is common in carriage isolates of S. pneumoniae from children in Vietnam. PMID:10681307

Coping with antibiotic resistance: combining nanoparticles with antibiotics and other antimicrobial agents.

PubMed

Allahverdiyev, Adil M; Kon, Kateryna Volodymyrivna; Abamor, Emrah Sefik; Bagirova, Malahat; Rafailovich, Miriam

2011-11-01

The worldwide escalation of bacterial resistance to conventional medical antibiotics is a serious concern for modern medicine. High prevalence of multidrug-resistant bacteria among bacteria-based infections decreases effectiveness of current treatments and causes thousands of deaths. New improvements in present methods and novel strategies are urgently needed to cope with this problem. Owing to their antibacterial activities, metallic nanoparticles represent an effective solution for overcoming bacterial resistance. However, metallic nanoparticles are toxic, which causes restrictions in their use. Recent studies have shown that combining nanoparticles with antibiotics not only reduces the toxicity of both agents towards human cells by decreasing the requirement for high dosages but also enhances their bactericidal properties. Combining antibiotics with nanoparticles also restores their ability to destroy bacteria that have acquired resistance to them. Furthermore, nanoparticles tagged with antibiotics have been shown to increase the concentration of antibiotics at the site of bacterium-antibiotic interaction, and to facilitate binding of antibiotics to bacteria. Likewise, combining nanoparticles with antimicrobial peptides and essential oils generates genuine synergy against bacterial resistance. In this article, we aim to summarize recent studies on interactions between nanoparticles and antibiotics, as well as other antibacterial agents to formulate new prospects for future studies. Based on the promising data that demonstrated the synergistic effects of antimicrobial agents with nanoparticles, we believe that this combination is a potential candidate for more research into treatments for antibiotic-resistant bacteria.

A case study of preservation of semi-solid preparations using the European Pharmacopoeia test: comparative efficacy of antimicrobial agents in zinc gelatin.

PubMed

Favet, J; Chappuis, M L; Doelker, E

2001-09-01

The present study was undertaken with the aim of finding an alternative preservative system to methyl parahydroxybenzoate in zinc gelatin, which was described in the monographs of the Swiss Pharmacopoeia (until Ph. Helv. 8) and in previous editions of the German Pharmacopoeia (until DAB 7). This antimicrobial agent has now been withdrawn in the DAB, because of its potential allergy risks. As for the USP and DAB-DDR zinc gelatin preparations, they have always been devoid of any preservative agent, probably relying on the mild antimicrobial activity of zinc. A literature survey did not reveal if such an aqueous preparation containing the water-insoluble zinc oxide shows efficacious antimicrobial activity by itself. Thus, a comparative evaluation of differently preserved zinc gelatin preparations was performed using a test for the efficacy of antimicrobial preservation that has been modified with regard to the European Pharmacopoeia (EP) test to take into account the solid state of the preparations and the bactericidal effect of the zinc. Three zinc gelatin preparations were checked, either: (i), without any agent; or (ii), with 0.1% methyl parahydroxybenzoate; or (iii), with 0.5% phenoxyethanol, a broad-spectrum antimicrobial agent almost devoid of allergy risks. The three preparations behave quite differently, in particular with respect to fungi. All three preparations passed the modified EP test as far as bacteria are concerned. Even zinc gelatin without preservative is very effective, not only because of the mild antimicrobial activity of zinc (the soluble fraction of zinc oxide in the liquid phase of zinc gelatin was determined to be 13 microg/ml), but most probably because of the low water activity of the preparation (measured as around 0.81), as shown by the absence of growth of a zinc-resistant strain of Pseudomonas aeruginosa. Zinc gelatin preserved with methyl parahydroxybenzoate has a weak, although satisfactory, activity against Staphylococcus aureus

Drug Susceptibility Testing of 31 Antimicrobial Agents on Rapidly Growing Mycobacteria Isolates from China.

PubMed

Pang, Hui; Li, Guilian; Zhao, Xiuqin; Liu, Haican; Wan, Kanglin; Yu, Ping

2015-01-01

Several species of rapidly growing mycobacteria (RGM) are now recognized as human pathogens. However, limited data on effective drug treatments against these organisms exists. Here, we describe the species distribution and drug susceptibility profiles of RGM clinical isolates collected from four southern Chinese provinces from January 2005 to December 2012. Clinical isolates (73) were subjected to in vitro testing with 31 antimicrobial agents using the cation-adjusted Mueller-Hinton broth microdilution method. The isolates included 55 M. abscessus, 11 M. fortuitum, 3 M. chelonae, 2 M. neoaurum, and 2 M. septicum isolates. M. abscessus (75.34%) and M. fortuitum (15.07%), the most common species, exhibited greater antibiotic resistance than the other three species. The isolates had low resistance to amikacin, linezolid, and tigecycline, and high resistance to first-line antituberculous agents, amoxicillin-clavulanic acid, rifapentine, dapsone, thioacetazone, and pasiniazid. M. abscessus and M. fortuitum were highly resistant to ofloxacin and rifabutin, respectively. The isolates showed moderate resistance to the other antimicrobial agents. Our results suggest that tigecycline, linezolid, clofazimine, and cefmetazole are appropriate choices for M. abscessus infections. Capreomycin, sulfamethoxazole, tigecycline, clofazimine, and cefmetazole are potentially good choices for M. fortuitum infections. Our drug susceptibility data should be useful to clinicians.

Drug Susceptibility Testing of 31 Antimicrobial Agents on Rapidly Growing Mycobacteria Isolates from China

PubMed Central

Pang, Hui; Li, Guilian; Zhao, Xiuqin; Liu, Haican; Wan, Kanglin; Yu, Ping

2015-01-01

Objectives. Several species of rapidly growing mycobacteria (RGM) are now recognized as human pathogens. However, limited data on effective drug treatments against these organisms exists. Here, we describe the species distribution and drug susceptibility profiles of RGM clinical isolates collected from four southern Chinese provinces from January 2005 to December 2012. Methods. Clinical isolates (73) were subjected to in vitro testing with 31 antimicrobial agents using the cation-adjusted Mueller-Hinton broth microdilution method. The isolates included 55 M. abscessus, 11 M. fortuitum, 3 M. chelonae, 2 M. neoaurum, and 2 M. septicum isolates. Results. M. abscessus (75.34%) and M. fortuitum (15.07%), the most common species, exhibited greater antibiotic resistance than the other three species. The isolates had low resistance to amikacin, linezolid, and tigecycline, and high resistance to first-line antituberculous agents, amoxicillin-clavulanic acid, rifapentine, dapsone, thioacetazone, and pasiniazid. M. abscessus and M. fortuitum were highly resistant to ofloxacin and rifabutin, respectively. The isolates showed moderate resistance to the other antimicrobial agents. Conclusions. Our results suggest that tigecycline, linezolid, clofazimine, and cefmetazole are appropriate choices for M. abscessus infections. Capreomycin, sulfamethoxazole, tigecycline, clofazimine, and cefmetazole are potentially good choices for M. fortuitum infections. Our drug susceptibility data should be useful to clinicians. PMID:26351633

Antimicrobial activity of Eucalyptus camaldulensis essential oils and their interactions with conventional antimicrobial agents against multi-drug resistant Acinetobacter baumannii.

PubMed

Knezevic, Petar; Aleksic, Verica; Simin, Natasa; Svircev, Emilija; Petrovic, Aleksandra; Mimica-Dukic, Neda

2016-02-03

Traditional herbal medicine has become an important issue on the global scale during the past decade. Among drugs of natural origin, special place belongs to essential oils, known as strong antimicrobial agents that can be used to combat antibiotic-resistant bacteria. Eucalyptus camaldulensis leaves are traditional herbal remedy used for various purposes, including treatment of infections. The aim of this study was to determine antimicrobial potential of two E. camaldulensis essential oils against multi-drug resistant (MDR) Acinetobacter baumannii wound isolates and to examine possible interactions of essential oils with conventional antimicrobial agents. Chemical composition of essential oils was determined by gas chromatography-mass spectrometry analysis (GC-MS). MIC values of essential oils against A. baumannii strains were estimated by modified broth microdilution method. The components responsible for antimicrobial activity were detected by bioautographic analysis. The potential synergy between the essential oils and antibiotics (ciprofloxacin, gentamicin and polymyxin B) was examined by checkerboard method and time kill curve. The dominant components of both essential oils were spatulenol, cryptone, p-cimene, 1,8-cineole, terpinen-4-ol and β-pinene. The detected MICs for the E. camaldulensis essential oils were in range from 0.5 to 2 μl mL(-1). The bioautographic assay confirmed antibacterial activity of polar terpene compounds. In combination with conventional antibiotics (ciprofloxacin, gentamicin and polymyxin B), the examined essential oils showed synergistic antibacterial effect in most of the cases, while in some even re-sensitized MDR A. baumannii strains. The synergistic interaction was confirmed by time-kill curves for E. camaldulensis essential oil and polymyxin B combination which reduced bacterial count under detection limit very fast, i.e. after 6h of incubation. The detected anti-A. baumannii activity of E. camaldulensis essential oils

Determination of the Mutant Prevention Concentration and the Mutant Selection Window of Topical Antimicrobial Agents against Propionibacterium acnes.

PubMed

Nakase, Keisuke; Nakaminami, Hidemasa; Toda, Yuta; Noguchi, Norihisa

2017-01-01

Determination of the mutant prevention concentration (MPC) and the mutant selection window (MSW) of antimicrobial agents used to treat pathogenic bacteria is important in order to apply effective antimicrobial therapies. Here, we determined the MPCs of the major topical antimicrobial agents against Propionibacterium acnes and Staphylococcus aureus which cause skin infections and compared their MSWs. Among the MPCs of nadifloxacin and clindamycin, the clindamycin MPC was determined to be the lowest against P. acnes. In contrast, the nadifloxacin MPC was the lowest against S. aureus. Calculations based on the minimum inhibitory concentrations and MPCs showed that clindamycin has the lowest MSW against both P. acnes and S. aureus. Nadifloxacin MSWs were 4-fold higher against P. acnes than against S. aureus. It is more likely for P. acnes to acquire resistance to fluoroquinolones than S. aureus. Therefore, topical application of clindamycin contributes very little to the emergence of resistant P. acnes and S. aureus strains. © 2016 S. Karger AG, Basel.

Antimicrobials in beekeeping.

PubMed

Reybroeck, Wim; Daeseleire, Els; De Brabander, Hubert F; Herman, Lieve

2012-07-06

The bee diseases American and European foulbrood and nosemosis can be treated with anti-infectious agents. However, in the EU and the USA the use of these agents in beekeeping is strictly regulated due to the lack of tolerance (e.g. Maximum Residue Limit) for residues of antibiotics and chemotherapeutics in honey. This article reviews the literature dealing with antimicrobials of interest in apiculture, stability of these antimicrobials in honey, and disposition of the antimicrobials in honeybee hives. Copyright © 2012 Elsevier B.V. All rights reserved.

Microbiological aspects of an in situ model to study effects of antimicrobial agents on dental plaque ecology.

PubMed

Giertsen, E; Guggenheim, B; Thurnheer, T; Gmür, R

2000-10-01

This study validates an in situ model for ecological studies of dental plaque exposed to various antimicrobial agents with different modes of action on plaque bacteria. Eleven subjects wore two acrylic appliances, each containing two bovine enamel discs, during two 1-wk test periods. Using a split-mouth crossover design, the appliances were dipped twice daily for 1 min into water (control; treatment A), fluoride (26.3 mM NaF; B), zinc acetate (20.0 mM; C), or fluoride plus zinc acetate (D). Four of the subjects used also chlorhexidine diacetate (2.2 mM; E) and chlorhexidine plus fluoride (F). At the end of each period, plaque was collected from the discs, after which the microbiota were analyzed by culture, automated quantitative immunofluorescence, and a viability fluorescence stain. As compared to control, treatments B, C, and D resulted in a significant reduction of individual taxa as detected by immunofluorescence, whereas similar bacterial viability and total bacterial numbers were observed. In contrast, chlorhexidine significantly reduced bacterial viability, total cell numbers, and the abundance of most of the enumerated taxa. We conclude that this in situ model is well suited to study effects of antimicrobial agents on dental plaque ecology. Combined with viability testing, immunofluorescence is obviously superior to culture in detecting taxa-specific shifts caused by antimicrobial agents.

Plant Products as Antimicrobial Agents

PubMed Central

Cowan, Marjorie Murphy

1999-01-01

The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and “leads” which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations. PMID:10515903

An Injectable System for Local and Sustained Release of Antimicrobial Agents in the Periodontal Pocket.

PubMed

Morelli, Laura; Cappelluti, Martino Alfredo; Ricotti, Leonardo; Lenardi, Cristina; Gerges, Irini

2017-08-01

Periodontitis treatments usually require local administration of antimicrobial drugs with the aim to reduce the bacterial load inside the periodontal pocket. Effective pharmaceutical treatments may require sustained local drug release for several days in the site of interest. Currently available solutions are still not able to fulfill the clinical need for high-quality treatments, mainly in terms of release profiles and patients' comfort. This work aims to fill this gap through the development of an in situ gelling system, capable to achieve controlled and sustained release of antimicrobial agents for medium-to-long-term treatments. The system is composed of micrometer-sized β-cyclodextrin-based hydrogel (bCD-Jef-MPs), featured by a strong hydrophilic character, suspended in a synthetic block-co-polymer solution (Poloxamer 407), which is capable to undergo rapid thermally induced sol-gel phase transition at body temperature. The chemical structure of bCD-Jef-MPs was confirmed by cross-correlating data from Fourier transform infrared (FTIR) spectroscopy, swelling test, and degradation kinetics. The thermally induced sol-gel phase transition is demonstrated by rheometric tests. The effectiveness of the described system to achieve sustained release of antimicrobial agents is demonstrated in vitro, using chlorhexidine digluconate as a drug model. The results achieved in this work disclose the potential of the mentioned system in effectively treating periodontitis lesions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel food packaging systems with natural antimicrobial agents.

PubMed

Irkin, Reyhan; Esmer, Ozlem Kizilirmak

2015-10-01

A new type of packaging that combines food packaging materials with antimicrobial substances to control microbial surface contamination of foods to enhance product microbial safety and to extend shelf-life is attracting interest in the packaging industry. Several antimicrobial compounds can be combined with different types of packaging materials. But in recent years, since consumer demand for natural food ingredients has increased because of safety and availability, these natural compounds are beginning to replace the chemical additives in foods and are perceived to be safer and claimed to alleviate safety concerns. Recent research studies are mainly focused on the application of natural antimicrobials in food packaging system. Biologically derived compounds like bacteriocins, phytochemicals, enzymes can be used in antimicrobial food packaging. The aim of this review is to give an overview of most important knowledge about application of natural antimicrobial packagings with model food systems and their antimicrobial effects on food products.

Food Antimicrobials Nanocarriers

PubMed Central

Blanco-Padilla, Adriana; Soto, Karen M.; Hernández Iturriaga, Montserrat

2014-01-01

Natural food antimicrobials are bioactive compounds that inhibit the growth of microorganisms involved in food spoilage or food-borne illness. However, stability issues result in degradation and loss of antimicrobial activity. Nanoencapsulation allows protection of antimicrobial food agents from unfavorable environmental conditions and incompatibilities. Encapsulation of food antimicrobials control delivery increasing the concentration of the antimicrobials in specific areas and the improvement of passive cellular absorption mechanisms resulted in higher antimicrobial activity. This paper reviews the present state of the art of the nanostructures used as food antimicrobial carriers including nanoemulsions, nanoliposomes, nanoparticles, and nanofibers. PMID:24995363

Antimicrobial peptides as potential anti-biofilm agents against multidrug-resistant bacteria.

PubMed

Chung, Pooi Yin; Khanum, Ramona

2017-08-01

Bacterial resistance to commonly used drugs has become a global health problem, causing increased infection cases and mortality rate. One of the main virulence determinants in many bacterial infections is biofilm formation, which significantly increases bacterial resistance to antibiotics and innate host defence. In the search to address the chronic infections caused by biofilms, antimicrobial peptides (AMP) have been considered as potential alternative agents to conventional antibiotics. Although AMPs are commonly considered as the primitive mechanism of immunity and has been extensively studied in insects and non-vertebrate organisms, there is now increasing evidence that AMPs also play a crucial role in human immunity. AMPs have exhibited broad-spectrum activity against many strains of Gram-positive and Gram-negative bacteria, including drug-resistant strains, and fungi. In addition, AMPs also showed synergy with classical antibiotics, neutralize toxins and are active in animal models. In this review, the important mechanisms of action and potential of AMPs in the eradication of biofilm formation in multidrug-resistant pathogen, with the goal of designing novel antimicrobial therapeutics, are discussed. Copyright © 2017. Published by Elsevier B.V.

Edible coating as carrier of antimicrobial agents to extend the shelf life of fresh-cut apples

USDA-ARS?s Scientific Manuscript database

Edible coatings with antimicrobial agents can extend shelf-life of fresh-cut fruits. The effect of lemongrass, oregano oil and vanillin incorporated in apple puree-alginate edible coatings, on shelf-life of fresh-cut 'Fuji' apples, was investigated. Coated apples were packed in air filled polypropyl...

Antimicrobial Peptides: An Emerging Category of Therapeutic Agents.

PubMed

Mahlapuu, Margit; Håkansson, Joakim; Ringstad, Lovisa; Björn, Camilla

2016-01-01

Antimicrobial peptides (AMPs), also known as host defense peptides, are short and generally positively charged peptides found in a wide variety of life forms from microorganisms to humans. Most AMPs have the ability to kill microbial pathogens directly, whereas others act indirectly by modulating the host defense systems. Against a background of rapidly increasing resistance development to conventional antibiotics all over the world, efforts to bring AMPs into clinical use are accelerating. Several AMPs are currently being evaluated in clinical trials as novel anti-infectives, but also as new pharmacological agents to modulate the immune response, promote wound healing, and prevent post-surgical adhesions. In this review, we provide an overview of the biological role, classification, and mode of action of AMPs, discuss the opportunities and challenges to develop these peptides for clinical applications, and review the innovative formulation strategies for application of AMPs.

Synergy between antibiotics and natural agents results in increased antimicrobial activity against Staphylococcus epidermidis.

PubMed

Abidi, Syed Hani; Ahmed, Khalid; Sherwani, Sikander Khan; Kazmi, Shahana Urooj

2015-09-27

Staphylococcus epidermidis is one of the most frequent causes of biofilm-associated infections on indwelling medical devices. With the emergence of methicillin-resistant S. epidermidis (MRSE), there is an urgent need to discover novel active agents against a range of Gram-positive pathogens. We screened the clinical isolates of S. epidermidis for susceptibility/resistance against commonly prescribed antibiotics. Furthermore, we tested some natural agents alone and in combination with antibiotics to find possible synergistic antimicrobial effects. S. epidermidis clinical isolates were screened for susceptibility/resistance against vancomycin, erythromycin, tetracycline, chloramphenicol, ampicillin, ofloxacin, cephalexin, and gentamicin using the Kirby-Bauer disk diffusion method. The antimicrobial potential of Camellia sinensis, Juglans regia, and Hippophae rhamnoides alone and in combination with antibiotics were examined using the disk diffusion method, where the antimicrobial potential activity was measured in terms of formation of zones of inhibition. Most S. epidermidis isolates were found to be resistant to one or more antibiotics. Gentamycin and ofloxacin were found to be the most effective antibiotics against S. epidermidis isolates. Extracts of Hippophae rhamnoides, Juglans regia, and Camellia sinensis were found to be equally effective against S. epidermidis isolates. In combination with antibiotics, these extracts exhibited appreciable synergistic activity; the highest synergistic activity was observed with erythromycin and cephalexin. In the case of cephalexin, a reversion in resistance was observed. The plant extracts used in the study exhibited additive and synergistic antibacterial activity against S. epidermidis, hence providing an effective alternative to deal with the problem of multidrug resistance.

Efficacy of Yeast' Vacuoles as Antimicrobial Agents to Escherichia coli Bacteremia in Rat.

PubMed

Yoon, Jihee; Cho, Ho-Seong; Park, Chul; Park, Byoung-Yong; Kim, Yang-Hoon; Min, Jiho

2017-01-01

Yeast vacuoles, lysosomes, are cell organelles that have antimicrobial activity against several bacteria in vitro. Lysosomes have a potential application to the treatment of pathogens such as antibiotics in vivo. Therefore, the in vivo efficacy of lysosomes was examined in a rat infection model against pathogenic Escherichia coli with varying susceptibilities to standard antimicrobial agents. Before in vivo testing, the concentration-dependent safety of lysosomes was confirmed by blood test and histopathology of normal rats. The therapeutic efficacy of lysosomes was examined in terms of the survival of E. coli in infected rat blood. The complete blood count and histopathology results were affected by the lysosomes concentration. In addition, the E. coli growth was inhibited by the initial injection of lysosomes. These results support the use of lysosomes as a bacterial inhibitor of an infected rat model.

Use of Extract of Citrus sinensis as an antimicrobial agent for foodborne zoonotic pathogens and spoilage bacteria

USDA-ARS?s Scientific Manuscript database

Foodborne pathogens remain global health problems despite concerted efforts to control the transmission of these microorganisms through food. The resurgence of drug resistant bacteria has renewed interest in developing and testing new sources of antimicrobial agents to control foodborne illness. Thi...

Absorbent silver (I) antimicrobial fabrics

USDA-ARS?s Scientific Manuscript database

In recent years, silver in form of silver ions, has been gaining importance in the wound management as an effective broad-spectrum antimicrobial agent. Silver has a long history as an antimicrobial agent, especially in the treatment of wounds. Alginates and carboxymethyl (CM) cotton contain carboxyl...

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.

In vivo antimicrobial activity of silver nanoparticles produced via a green chemistry synthesis using Acacia rigidula as a reducing and capping agent.

PubMed

Escárcega-González, Carlos Enrique; Garza-Cervantes, J A; Vázquez-Rodríguez, A; Montelongo-Peralta, Liliana Zulem; Treviño-González, M T; Díaz Barriga Castro, E; Saucedo-Salazar, E M; Chávez Morales, R M; Regalado Soto, D I; Treviño González, F M; Carrazco Rosales, J L; Cruz, Rocío Villalobos; Morones-Ramírez, José Rubén

2018-01-01

One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells. In this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo. The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet-visible, and Fourier transform infrared. We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative ( Escherichia coli , Pseudomonas aeruginosa , and a clinical multidrug-resistant strain of P. aeruginosa ) and Gram-positive ( Bacillus subtilis ) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the

In vivo antimicrobial activity of silver nanoparticles produced via a green chemistry synthesis using Acacia rigidula as a reducing and capping agent

PubMed Central

Escárcega-González, Carlos Enrique; Garza-Cervantes, JA; Vázquez-Rodríguez, A; Montelongo-Peralta, Liliana Zulem; Treviño-González, MT; Díaz Barriga Castro, E; Saucedo-Salazar, EM; Chávez Morales, RM; Regalado Soto, DI; Treviño González, FM; Carrazco Rosales, JL; Cruz, Rocío Villalobos; Morones-Ramírez, José Rubén

2018-01-01

Introduction One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells. Purpose In this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo. Materials and methods The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet–visible, and Fourier transform infrared. Results We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and a clinical multidrug-resistant strain of P. aeruginosa) and Gram-positive (Bacillus subtilis) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were

In-vitro susceptibility of 1982 respiratory tract pathogens and 1921 urinary tract pathogens against 19 antimicrobial agents: a Canadian multicentre study. Canadian Antimicrobial Study Group.

PubMed

Blondeau, J M; Yaschuk, Y; Suter, M; Vaughan, D

1999-03-01

A total of 3903 pathogens from 48 Canadian medical centres were tested against 19 antimicrobial agents. Five agents showed activity against > or = 90% of all 1982 respiratory tract pathogens tested (ciprofloxacin, 90%; cefoperazone, 91%; ticarcillin/clavulanate, 92%; ceftazidime and imipenem, 93% each). Nine agents had > or = 90% activity against Enterobacteriaceae from respiratory tract infection (cefotaxime and ticarcillin/clavulanate, 90% each; aztreonam, ceftizoxime and ceftriaxone, 91% each; ceftazidime, 93%; ciprofloxacin, 97%; imipenem and netilmicin, 98% each). Similarly, five agents had activity against > or = 90% of all 1921 urinary tract pathogens tested (ciprofloxacin and ticarcillin/clavulanate, 90% each; cefoperazone and netilmicin, 91% each; imipenem, 99%). Nine agents had > or = 95% activity against Enterobacteriaceae from urinary tract infection (ciprofloxacin, 95%; cefotetan, 97%; aztreonam, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone and netilmicin, 98% each; imipenem, 99%). Seventeen agents had activity against > or = 95% of Staphylococcus aureus strains. Susceptibility of Pseudomonas aeruginosa isolates ranged from 2% to 91%.

Synthesis, Characterization and Biological Evaluation of Some Quinoxaline Derivatives: A Promising and Potent New Class of Antitumor and Antimicrobial Agents.

PubMed

Al-Marhabi, Aisha R; Abbas, Hebat-Allah S; Ammar, Yousry A

2015-11-03

In continuation of our endeavor towards the development of potent and effective anticancer and antimicrobial agents; the present work deals with the synthesis of some novel tetrazolo[1,5-a]quinoxalines, N-pyrazoloquinoxalines, the corresponding Schiff bases, 1,2,4-triazinoquinoxalines and 1,2,4-triazoloquinoxalines. These compounds were synthesized via the reaction of the key intermediate hydrazinoquinoxalines with various reagents and evaluated for anticancer and antimicrobial activity. The results indicated that tetrazolo[1,5-a]quinoxaline derivatives showed the best result, with the highest inhibitory effects towards the three tested tumor cell lines, which were higher than that of the reference doxorubicin and these compounds were non-cytotoxic to normal cells (IC50 values > 100 μg/mL). Also, most of synthesized compounds exhibited the highest degrees of inhibition against the tested strains of Gram positive and negative bacteria, so tetrazolo[1,5-a]quinoxaline derivatives show dual activity as anticancer and antimicrobial agents.

Effects of antimicrobial treatment on fiberglass-acrylic filters.

PubMed

Cecchini, C; Verdenelli, M C; Orpianesi, C; Dadea, G M; Cresci, A

2004-01-01

The aims of the present study were to: (i) analyse a group of antimicrobial agents and to select the most active against test microbial strains; (ii) test the effect of the antimicrobial treatment on air filters in order to reduce microbial colonization. Different kinds of antimicrobial agents were analysed to assess their compatibility with the production process of air filter media. The minimal inhibitory concentration for each antimicrobial agent was determined against a defined list of microbial strains, and an antimicrobial activity assay of filter prototypes was developed to determine the most active agent among the compatible antimicrobials. Then, the most active was chosen and added directly to the filter during the production process. The microbial colonization of treated and untreated filter media was assessed at different working times for different incubation times by stereomicroscope and scanning electron microscope analysis. Some of the antimicrobial agents analysed were more active against microbial test strains and compatible with the production process of the filter media. Filter sections analysis of treated filter media showed a significantly lower microbial colonization than those untreated, a reduction of species both in density and varieties and of the presence of bacteria and fungal hyphae with reproductive structures. This study demonstrated the ability of antimicrobial treatments to inhibit the growth of micro-organisms in filter media and subsequently to increase indoor air quality (IAQ), highlighting the value of adding antimicrobials to filter media. To make a contribution to solving the problem of microbial contamination of air filters, by demonstrating the efficacy of incorporating antimicrobial agents in the filter media to improve IAQ and health.

Antimicrobial activity of Olea europaea Linné extracts and their applicability as natural food preservative agents.

PubMed

Thielmann, J; Kohnen, S; Hauser, C

2017-06-19

The antimicrobial activity of phenolic compounds from Olea (O.) europaea Linné (L.) is part of the scientific discussion regarding the use of natural plant extracts as alternative food preservative agents. Although, the basic knowledge on the antimicrobial potential of certain molecules such as oleuropein, hydroxytyrosol or elenolic acid derivatives is given, there is still little information regarding their applicability for food preservation. This might be primarily due to the lack of information regarding the full antimicrobial spectrum of the compounds, their synergisms in natural or artificial combinations and their interaction with food ingredients. The present review accumulates available literature from the past 40 years, investigating the antimicrobial activity of O. europaea L. derived extracts and compounds in vitro and in food matrices, in order to evaluate their food applicability. In summary, defined extracts from olive fruit or leaves, containing the strongest antimicrobial compounds hydroxytyrosol, oleacein or oleacanthal in considerable concentrations, appear to be suitable for food preservation. Nonetheless there is still need for consequent research on the compounds activity in food matrices, their effect on the natural microbiota of certain foods and their influence on the sensorial properties of the targeted products. Copyright © 2017 Elsevier B.V. All rights reserved.

In vitro susceptibility of Helicobacter pullorum strains to different antimicrobial agents.

PubMed

Ceelen, Liesbeth; Decostere, Annemie; Devriese, Luc A; Ducatelle, Richard; Haesebrouck, Freddy

2005-01-01

The in vitro activity of 13 antimicrobial agents against 23 Helicobacter pullorum strains from poultry (21) and human (two) origin, and one human H. canadensis strain was tested by the agar dilution method. With the H. pullorum strains, monomodal distributions of Minimum Inhibitory Concentrations (MICs) were seen with lincomycin, doxycycline, gentamicin, tobramycin, erythromycin, tylosin, metronidazole, and enrofloxacin in concentration ranges considered as indicating susceptibility in other bacteria. The normal susceptibility level for nalidixic acid was situated at or slightly above the MIC breakpoints proposed for Campylobacteriaceae. Ampicillin, ceftriaxone, and sulphamethoxazole-trimethoprim showed poor activity against H. pullorum. For the H. canadensis strain, a similar susceptibility pattern was seen, except for nalidixic acid and enrofloxacin, whose MIC of >512 and 8 microg/ml, respectively, indicated resistance of this agent. With spectinomycin, a bimodal distribution of the MICs was noted for the tested strains; eight H. pullorum isolates originating from one flock showed acquired resistance (MIC>512 microg/ml).

Top 1% of Inpatients Administered Antimicrobial Agents Comprising 50% of Expenditures: A Descriptive Study and Opportunities for Stewardship Intervention.

PubMed

Dela-Pena, Jennifer; Kerstenetzky, Luiza; Schulz, Lucas; Kendall, Ron; Lepak, Alexander; Fox, Barry

2017-03-01

OBJECTIVE To characterize the top 1% of inpatients who contributed to the 6-month antimicrobial budget in a tertiary, academic medical center and identify cost-effective intervention opportunities targeting high-cost antimicrobial utilization. DESIGN Retrospective cohort study. PATIENTS Top 1% of the antimicrobial budget from July 1 through December 31, 2014. METHODS Patients were identified through a pharmacy billing database. Baseline characteristics were collected through a retrospective medical chart review. Patients were presented to the antimicrobial stewardship team to determine appropriate utilization of high-cost antimicrobials and potential intervention opportunities. Appropriate use was defined as antimicrobial therapy that was effective, safe, and most cost-effective compared with alternative agents. RESULTS A total of 10,460 patients received antimicrobials in 6 months; 106 patients accounted for $889,543 (47.2%) of the antimicrobial budget with an antimicrobial cost per day of $219±$192 and antimicrobial cost per admission of $4,733±$7,614. Most patients were immunocompromised (75%) and were followed by the infectious disease consult service (80%). The most commonly prescribed antimicrobials for treatment were daptomycin, micafungin, liposomal amphotericin B, and meropenem. Posaconazole and valganciclovir accounted for most of the prophylactic therapy. Cost-effective opportunities (n=71) were present in 57 (54%) of 106 patients, which included dose optimization, de-escalation, dosage form conversion, and improvement in transitions of care. CONCLUSION Antimicrobial stewardship oversight is important in implementing cost-effective strategies, especially in complex and immunocompromised patients who require the use of high-cost antimicrobials. Infect Control Hosp Epidemiol 2017;38:259-265.

Consumer-mediated nutrient recycling is influenced by interactions between nutrient enrichment and the anti-microbial agent triclosan

USDA-ARS?s Scientific Manuscript database

Triclosan (5-chloro-2-(2, 4-dichlorophenoxy)phenol) is a widely used antimicrobial agent in personal care products whose fate and transport in aquatic ecosystems is a growing environmental concern. Evidence for chronic ecological effects of triclosan in aquatic organisms is increasing. At larger sca...

Antimicrobial activity of chemomechanical gingival retraction products.

PubMed

Hsu, Belinda; Lee, Stephanie; Schwass, Donald; Tompkins, Geoffrey

2017-07-01

Application of astringent hemostatic agents is the most widely used technique for gingival retraction, and a variety of products are offered commercially. However, these products may have additional unintended yet clinically beneficial properties. The authors assessed the antimicrobial activities of marketed retraction products against plaque-associated bacteria in both planktonic and biofilm assays, in vitro. The authors assessed hemostatic solutions, gels, pellets, retraction cords, pastes, and their listed active agents against a collection of microorganisms by means of conventional agar diffusion and minimum bacteriostatic and bactericidal concentration determinations. The authors then tested the most active products against monospecies biofilms grown on hydroxyapatite disks. All of the tested retraction products exhibited some antimicrobial activity. The results of the most active products were comparable with those of a marketed mouthwash. The listed retraction-active agents displayed relatively little activity when tested in pure form. At 10% dilution, some products evidenced inhibitory activity against most tested bacteria within 3 minutes of exposure, whereas others displayed variable effects after 10 minutes. The most active agents reduced, but did not completely prevent, the metabolic activity of a monospecies biofilm. Commercial gingival retraction products exhibit antimicrobial effects to various degrees in vitro. Some products display rapid bactericidal activity. The antimicrobial activity is not owing to the retraction-active agents. Biofilm bacteria are less sensitive to the antimicrobial effects of the agents. The rapidity of killing by some hemostatic agents suggests an antimicrobial effect that may be efficacious during clinical placement. The results of this in vitro study suggest that clinicians should be aware of the potential antimicrobial effects of some hemostatic agents, but more research is needed to confirm these observations in

Recent updates of marine antimicrobial peptides.

PubMed

Semreen, Mohammad H; El-Gamal, Mohammed I; Abdin, Shifaa; Alkhazraji, Hajar; Kamal, Leena; Hammad, Saba; El-Awady, Faten; Waleed, Dima; Kourbaj, Layal

2018-03-01

Antimicrobial peptides are group of proteins showing broad-spectrum antimicrobial activity that have been known to be powerful agents against a variety of pathogens. This class of compounds contributed to solving the microbial resistance dilemma that limited the use of many potent antimicrobial agents. The marine environment is known to be one of the richest sources for antimicrobial peptides, yet this environment is not fully explored. Hence, the scientific research attention should be directed toward the marine ecosystem as enormous amount of useful discoveries could be brought to the forefront. In the current article, the marine antimicrobial peptides reported from mid 2012 to 2017 have been reviewed.

Essential oils and their principal constituents as antimicrobial agents for synthetic packaging films.

PubMed

Kuorwel, Kuorwel K; Cran, Marlene J; Sonneveld, Kees; Miltz, Joseph; Bigger, Stephen W

2011-01-01

Spices and herbal plant species have been recognized to possess a broad spectrum of active constituents that exhibit antimicrobial (AM) activity. These active compounds are produced as secondary metabolites associated with the volatile essential oil (EO) fraction of these plants. A wide range of AM agents derived from EOs have the potential to be used in AM packaging systems which is one of the promising forms of active packaging systems aimed at protecting food products from microbial contamination. Many studies have evaluated the AM activity of synthetic AM and/or natural AM agents incorporated into packaging materials and have demonstrated effective AM activity by controlling the growth of microorganisms. This review examines the more common synthetic and natural AM agents incorporated into or coated onto synthetic packaging films for AM packaging applications. The focus is on the widely studied herb varieties including basil, oregano, and thyme and their EOs. © 2011 Institute of Food Technologists®

Emerging Gram negative resistance to last-line antimicrobial agents fosfomycin, colistin and ceftazidime-avibactam - epidemiology, laboratory detection and treatment implications.

PubMed

Sherry, Norelle; Howden, Benjamin

2018-04-01

Multidrug-resistant (MDR) and extensively-drug-resistant (XDR) Gram-negative bacteria have emerged as a major threat to human health globally. This has resulted in the 're-discovery' of some older antimicrobials and development of new agents, however resistance has also rapidly emerged to these agents. Areas covered: Here we describe recent developments in resistance to three of the most important last-line antimicrobials for treatment of MDR and XDR Gram negatives: fosfomycin, colistin and ceftazidime-avibactam. Expert commentary: A key challenge for microbiologists and clinicians using these agents for treating patients with MDR and XDR Gram negative infections is the need to ensure appropriate reference methods are being used to test susceptibility to these agents, especially colistin and fosfomycin. These methods are not available in all laboratories meaning accurate results are either delayed, or potentially inaccurate as non-reference methods are employed. Combination therapy for MDR and XDR Gram negatives is likely to become more common, and future studies should focus on the clinical effects of monotherapy vs combination therapy, as well as validation of synergy testing methods. Effective national and international surveillance systems to detect and respond to resistance to these last line agents are also critical.

Topical antimicrobial agents for the treatment of chronic wounds.

PubMed

Ousey, Karen; McIntosh, Caroline

2009-09-01

Chronic wounds are commonly observed in acute and community settings. The management of chronic wounds represents a significant proportion of health-care resources and makes up a substantial amount of contact time with community-based nurses spending approximately 25% to 50% of their time treating wounds. Chronic wounds often exhibit increased bacterial burden that can negatively impact upon patients, reduce their quality of life and substantially increase treatment costs for health care providers. Antibiotic resistance has become a major medical and public health problem, and interest has been generated in the use of topical therapies to manage wound infection. This article presents an overview of the historical use of honey, silver and iodine for the treatment of infected wounds progressing through to modern day use and the current evidence base for the use of these antimicrobial agents in the management of infected wounds.

Drug-induced liver injury due to antimicrobials, central nervous system agents, and nonsteroidal anti-inflammatory drugs.

PubMed

Devarbhavi, Harshad; Andrade, Raúl J

2014-05-01

Antimicrobial agents including antituberculosis (anti-TB) agents are the most common cause of idiosyncratic drug-induced liver injury (DILI) and drug-induced liver failure across the world. Better molecular and genetic biomarkers are acutely needed to help identify those at risk of liver injury particularly for those needing antituberculosis therapy. Some antibiotics such as amoxicillin-clavulanate and isoniazid consistently top the lists of agents in retrospective and prospective DILI databases. Central nervous system agents, particularly antiepileptics, account for the second most common class of agents implicated in DILI registries. Hepatotoxicity from older antiepileptics such as carbamazepine, phenytoin, and phenobarbital are often associated with hypersensitivity features, whereas newer antiepileptic drugs have a more favorable safety profile. Antidepressants and nonsteroidal anti-inflammatory drugs carry very low risk of significant liver injury, but their prolific use make them important causes of DILI. Early diagnosis and withdrawal of the offending agent remain the mainstays of minimizing hepatotoxicity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Synthesis and biological evaluation of pyrazolylthiazole carboxylic acids as potent anti-inflammatory-antimicrobial agents.

PubMed

Khloya, Poonam; Kumar, Satish; Kaushik, Pawan; Surain, Parveen; Kaushik, Dhirender; Sharma, Pawan K

2015-03-15

Current Letter presents design, synthesis and biological evaluation of a novel series of pyrazolylthiazole carboxylates 1a-1p and corresponding acid derivatives 2a-2p. All 32 novel compounds were tested for their in vivo anti-inflammatory activity by carrageenan-induced rat paw edema method as well as for in vitro antimicrobial activity. All the tested compounds exhibited excellent AI activity profile. Three compounds 1p (R=Cl, R(1)=Cl), 2c (R=H, R(1)=F) and 2n (R=Cl, R(1)=OCH3) were identified as potent anti-inflammatory agents exhibiting edema inhibition of 93.06-89.59% which is comparable to the reference drug indomethacin (91.32%) after 3h of carrageenan injection while most of the other compounds displayed inhibition ⩾80%. In addition, pyrazolylthiazole carboxylic acids (2a-2p) also showed good antimicrobial profile. Compound 2h (R=OCH3, R(1)=Cl) showed excellent antimicrobial activity (MIC 6.25μg/mL) against both Gram positive bacteria comparable with the reference drug ciprofloxacin (MIC 6.25μg/mL). Copyright © 2015 Elsevier Ltd. All rights reserved.

In vitro activities of 10 antimicrobial agents against bacterial vaginosis-associated anaerobic isolates from pregnant Japanese and Thai women.

PubMed

Puapermpoonsiri, S; Watanabe, K; Kato, N; Ueno, K

1997-10-01

The in vitro activities of 10 antimicrobial agents against 159 bacterial vaginosis-associated anaerobic isolates from pregnant Japanese and Thai women were determined. Clindamycin, imipenem, cefmetazole, amoxicillin, amoxicillin-clavulanate, and metronidazole were highly active against all anaerobic isolates except Prevotella bivia and Mobiluncus species, which were resistant to amoxicillin and metronidazole, respectively. Cefotiam, ceftazidime, and ofloxacin were variably effective, while cefaclor was the least effective agent.

Evaluation of new antimicrobial agents on Bacillus spp. strains: docking affinity and in vitro inhibition of glutamate-racemase.

PubMed

Tamay-Cach, Feliciano; Correa-Basurto, José; Villa-Tanaca, Lourdes; Mancilla-Percino, Teresa; Juárez-Montiel, Margarita; Trujillo-Ferrara, José G

2013-10-01

Three glutamic acid derivatives, two boron-containing and one imide-containing compound, were synthesized and tested for antimicrobial activity targeting glutamate-racemase. Antimicrobial effect was evaluated over Bacillus spp. Docking analysis shown that the test compounds bind near the active site of racemase isoforms, suggesting an allosteric effect. The boron derivatives had greater affinity than the imide derivative. In vitro assays shown good antimicrobial activity for the boron-containing compounds, and no effectiveness for the imide-containing compounds. The minimum inhibitory concentration of tetracycline, used as standard, was lower than that of the boron-containing derivatives. However, it seems that the boron-containing derivatives are more selective for bacteria. Experimental evidence suggests that the boron-containing derivatives act by inhibiting the racemase enzyme. Therefore, these test compounds probably impede the formation of the bacterial cell wall. Thus, the boron-containing glutamic acid derivatives should certainly be of interest for future studies as antimicrobial agents for Bacillus spp.

Synthesis of bio-based nanocomposites for controlled release of antimicrobial agents in food packaging

NASA Astrophysics Data System (ADS)

DeGruson, Min Liu

The utilization of bio-based polymers as packaging materials has attracted great attention in both scientific and industrial areas due to the non-renewable and nondegradable nature of synthetic plastic packaging. Polyhydroxyalkanoate (PHA) is a biobased polymer with excellent film-forming and coating properties, but exhibits brittleness, insufficient gas barrier properties, and poor thermal stability. The overall goal of the project was to develop the polyhydroxyalkanoate-based bio-nanocomposite films modified by antimicrobial agents with improved mechanical and gas barrier properties, along with a controlled release rate of antimicrobial agents for the inhibition of foodborne pathogens and fungi in food. The ability for antimicrobial agents to intercalate into layered double hydroxides depended on the nature of the antimicrobial agents, such as size, spatial structure, and polarity, etc. Benzoate and gallate anions were successfully intercalated into LDH in the present study and different amounts of benzoate anion were loaded into LDH under different reaction conditions. Incorporation of nanoparticles showed no significant effect on mechanical properties of polyhydroxybutyrate (PHB) films, however, significantly increased the tensile strength and elongation at break of polyhydroxybutyrate-co-valerate (PHBV) films. The effects of type and concentration of LDH nanoparticles (unmodified LDH and LDH modified by sodium benzoate and sodium gallate) on structure and properties of PHBV films were then studied. The arrangement of LDH in the bio-nanocomposite matrices ranged from exfoliated to phase-separated depending on the type and concentration of LDH nanoparticles. Intercalated or partially exfoliated structures were obtained using modified LDH, however, only phase-separated structures were formed using unmodified LDH. The mechanical (tensile strength and elongation at break) and thermo-mechanical (storage modulus) properties were significantly improved with low

In vitro susceptibility of rabbit strains of Clostridium spiroforme to antimicrobial agents.

PubMed

Carman, R J; Wilkins, T D

1991-08-30

Using an agar dilution method we measured the minimum inhibitory concentration (MIC) of 12 antimicrobial agents against 11 strains of iota-toxigenic strains of Clostridium spiroforme. Each strain was isolated from a separate outbreak of toxic diarrhoea of rabbits. Vancomycin and bacitracin, both agents used to treat intestinal clostridioses of humans and other animals, had a relatively high MIC (8 micrograms/ml or more). Metronidazole was uniformly active against C. spiroforme. With MIC of 8 micrograms/ml or more, both lincomycin (11 strains) and erythromycin (9 strains) were relatively inactive against C. spiroforme, conversely, penicillin G was active (MIC for 8 strains was 0.5 micrograms/ml or less). Exposure to any one of these drugs has been implicated as a predisposing factor for C. spiroforme mediated diarrhoea of rabbits. The greatest variation in MIC was seen for erythromycin (8-fold), penicillin G (8-fold) and tetracycline (16-fold).

Insights into Comparative Antimicrobial Efficacies of Synthetic and Organic Agents: The Case of ZnS Nanoparticles and Zingiber officinale Rosc.

NASA Astrophysics Data System (ADS)

Obidi, O. F.; Nejo, A. O.; Ayeni, R. A.; Revaprasadu, N.

2018-03-01

The differences among the antimicrobial activities of synthetic nanoparticles (NPs), organic agents and conventional antibiotics against human pathogens are little known. We compared the antimicrobial activities of aqueous, ethanol and ethyl acetate extracts of Zingiber officinale rhizomes with ZnS NPs and tetracycline/nystatin using agar-diffusion techniques. Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and ultraviolet spectroscopy were used to characterize ZnS NPs. At 100 mg/ml, ethanol and ethyl acetate extract inhibited Acinetobacter baumannii, Salmonella typhimurium, Enterococcus faecium, Shigella flexneri, Klebsiella pneumoniae, Staphylococcus epidermidis and Candida albicans with zones of inhibition (ZOI) ranging between 0-42 mm and 0-39 mm, respectively. Candida albicans had a remarkable ZOI of 42 mm and 22 mm from ethanol and ZnS NPs compared with 20 mm from conventional nystatin. TEM and FTIR revealed spherically shaped polydispersed NPs with particle size of 12.5 nm and the role of banana peel extracts in ZnS NPs synthesis. Organic and synthetic NPs proved potential alternatives to conventional antimicrobial agents.

Insights into Comparative Antimicrobial Efficacies of Synthetic and Organic Agents: The Case of ZnS Nanoparticles and Zingiber officinale Rosc.

NASA Astrophysics Data System (ADS)

Obidi, O. F.; Nejo, A. O.; Ayeni, R. A.; Revaprasadu, N.

2018-06-01

The differences among the antimicrobial activities of synthetic nanoparticles (NPs), organic agents and conventional antibiotics against human pathogens are little known. We compared the antimicrobial activities of aqueous, ethanol and ethyl acetate extracts of Zingiber officinale rhizomes with ZnS NPs and tetracycline/nystatin using agar-diffusion techniques. Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and ultraviolet spectroscopy were used to characterize ZnS NPs. At 100 mg/ml, ethanol and ethyl acetate extract inhibited Acinetobacter baumannii, Salmonella typhimurium, Enterococcus faecium, Shigella flexneri, Klebsiella pneumoniae, Staphylococcus epidermidis and Candida albicans with zones of inhibition (ZOI) ranging between 0-42 mm and 0-39 mm, respectively. Candida albicans had a remarkable ZOI of 42 mm and 22 mm from ethanol and ZnS NPs compared with 20 mm from conventional nystatin. TEM and FTIR revealed spherically shaped polydispersed NPs with particle size of 12.5 nm and the role of banana peel extracts in ZnS NPs synthesis. Organic and synthetic NPs proved potential alternatives to conventional antimicrobial agents.

The chemistry and applications of antimicrobial polymers: a state-of-the-art review.

PubMed

Kenawy, El-Refaie; Worley, S D; Broughton, Roy

2007-05-01

Microbial infection remains one of the most serious complications in several areas, particularly in medical devices, drugs, health care and hygienic applications, water purification systems, hospital and dental surgery equipment, textiles, food packaging, and food storage. Antimicrobials gain interest from both academic research and industry due to their potential to provide quality and safety benefits to many materials. However, low molecular weight antimicrobial agents suffer from many disadvantages, such as toxicity to the environment and short-term antimicrobial ability. To overcome problems associated with the low molecular weight antimicrobial agents, antimicrobial functional groups can be introduced into polymer molecules. The use of antimicrobial polymers offers promise for enhancing the efficacy of some existing antimicrobial agents and minimizing the environmental problems accompanying conventional antimicrobial agents by reducing the residual toxicity of the agents, increasing their efficiency and selectivity, and prolonging the lifetime of the antimicrobial agents. Research concerning the development of antimicrobial polymers represents a great a challenge for both the academic world and industry. This article reviews the state of the art of antimicrobial polymers primarily since the last comprehensive review by one of the authors in 1996. In particular, it discusses the requirements of antimicrobial polymers, factors affecting the antimicrobial activities, methods of synthesizing antimicrobial polymers, major fields of applications, and future and perspectives in the field of antimicrobial polymers.

The Potential of Antimicrobial Peptides as Biocides

PubMed Central

Laverty, Garry; Gorman, Sean P.; Gilmore, Brendan F.

2011-01-01

Antimicrobial peptides constitute a diverse class of naturally occurring antimicrobial molecules which have activity against a wide range of pathogenic microorganisms. Antimicrobial peptides are exciting leads in the development of novel biocidal agents at a time when classical antibiotics are under intense pressure from emerging resistance, and the global industry in antibiotic research and development stagnates. This review will examine the potential of antimicrobial peptides, both natural and synthetic, as novel biocidal agents in the battle against multi-drug resistant pathogen infections. PMID:22072905

[Susceptibility and resistence of Pseudomonas aeruginosa to antimicrobial agents].

PubMed

Gamero Delgado, M C; García-Mayorgas, A D; Rodríguez, F; Ibarra, A; Casal, M

2007-06-01

Pseudomonas aeruginosa is an opportunistic microorganism that is frequently the cause of nosocomial infections. Multiple mechanisms are involved in its natural and acquired resistance to many of the antimicrobial agents commonly used in clinical practice. The objective of this study was to assess the susceptibility and resistance patterns of P. aeruginosa strains isolated in Hospital Reina Sofia between 2000 and 2005, as well as to analyze the differences between intrahospital and extrahospital isolates in 2005 and to compare the results with those obtained in other studies. A total of 3,019 strains of P. aeruginosa from different hospitals and nonhospital settings were evaluated, taking into consideration their degree of sensitivity to different antibiotics. The MICs were determined by means of the Wider I automated system (Soria Melguizo), taking into consideration the criteria of susceptibility and resistance recommended by MENSURA. Results of the analysis showed that P. aeruginosa maintained similar levels of antimicrobial susceptibility during the period 2000-2005, with increased susceptibility to amikacin, gentamicin and tobramycin. There were also important differences in the degree of susceptibility between intrahospital and extrahospital strains, except for imipenem and fosfomycin. The intrahospital difference in susceptibility was also evaluated, emphasizing the importance of periodically studying susceptibility and resistance patterns of P. aeruginosa in each setting in order to evaluate different therapeutic guidelines, as it is not always advisable to extrapolate data from different regions. These differences can be explained by the different use of antibiotics in each center and the geographic variations of the resistance mechanisms of P. aeruginosa.

In Vitro Activities of the Everninomicin SCH 27899 and Other Newer Antimicrobial Agents against Borrelia burgdorferi

PubMed Central

Dever, Lisa L.; Torigian, Christine V.; Barbour, Alan G.

1999-01-01

The in vitro activity of the everninomicin antibiotic SCH 27899 against 17 isolates of Borrelia spp. was investigated. MICs ranged from 0.06 to 0.5 μg/ml. Time-kill studies with the B31 strain of B. burgdorferi demonstrated ≥3-log10-unit killing after 72 h with concentrations representing four times the MIC. The in vitro activity of four other newer antimicrobial agents, meropenem, cefepime, quinupristin-dalfopristin, and linezolid, was also tested against the B31 strain. Meropenem was the most potent of the latter agents, with an MIC of 0.125 μg/ml. PMID:10390242

Antimicrobial resistance mechanisms among Campylobacter.

PubMed

Wieczorek, Kinga; Osek, Jacek

2013-01-01

Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world. Humans most often become infected by ingesting contaminated food, especially undercooked chicken, but also other sources of bacteria have been described. Campylobacteriosis is normally a self-limiting disease. Antimicrobial treatment is needed only in patients with more severe disease and in those who are immunologically compromised. The most common antimicrobial agents used in the treatment of Campylobacter infections are macrolides, such as erythromycin, and fluoroquinolones, such as ciprofloxacin. Tetracyclines have been suggested as an alternative choice in the treatment of clinical campylobacteriosis but in practice are not often used. However, during the past few decades an increasing number of resistant Campylobacter isolates have developed resistance to fluoroquinolones and other antimicrobials such as macrolides, aminoglycosides, and beta-lactams. Trends in antimicrobial resistance have shown a clear correlation between use of antibiotics in the veterinary medicine and animal production and resistant isolates of Campylobacter in humans. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter are discussed.

Antimicrobial susceptibility survey on bacterial agents of canine and feline urinary tract infections: Weight of the empirical treatment.

PubMed

Rampacci, Elisa; Bottinelli, Marco; Stefanetti, Valentina; Hyatt, Doreene R; Sgariglia, Elisa; Coletti, Mauro; Passamonti, Fabrizio

2018-06-01

This work characterised the antimicrobial susceptibility of uropathogens isolated from empirically treated dogs and cats. Within-household transmission of uropathogens can involve humans and companion animals. Knowledge on the prevalence and susceptibility pattern of isolates from canine and feline urine samples and the impact of prior antimicrobial treatment is important to prevent the dissemination of antimicrobial resistance. A retrospective study was conducted selecting antibiotic-treated companion animals. Urine samples were collected by cystocentesis and were submitted to an Italian diagnostic laboratory over a 2-year period (2013-2015). The antimicrobial susceptibility of the isolates was analysed both using Clinical and Laboratory Standards Institute (CLSI) guidelines and a formula to help select rational antimicrobial therapy. Gram-negative bacteria were clearly prevalent. Gentamicin had the highest impact factors. Amoxicillin/clavulanic acid and doxycycline appeared to be the most effective compounds against Gram-positive infections, whilst marbofloxacin may be a useful option against Gram-negative urinary tract infections (UTIs) as well as doxycycline and trimethoprim/sulfamethoxazole in cats and dogs, respectively. Consulting published studies, a comparable overall trend regarding bacterial species incriminated in canine and feline UTIs and their susceptibilities seems likely, despite different circumstances where the studies were conducted. Companion animals are potential reservoirs of drug-resistant uropathogens. Judicious use of antibiotics is necessary to maintain the efficacy of antimicrobials in human and veterinary medicine. Antimicrobial susceptibility monitoring programmes are therefore essential to facilitate the choice of antimicrobial agent that is most likely to be effective, particularly in cases of prior antimicrobial treatment. Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. All rights reserved.

Vancomycin-modified Fe3O4@SiO2@Ag microflowers as effective antimicrobial agents.

PubMed

Wang, Chongwen; Zhang, Kehan; Zhou, Zhe; Li, Qingjun; Shao, Liting; Hao, Rong Zhang; Xiao, Rui; Wang, Shengqi

2017-01-01

Nanomaterials combined with antibiotics exhibit synergistic effects and have gained increasing interest as promising antimicrobial agents. In this study, vancomycin-modified magnetic-based silver microflowers (Van/Fe 3 O 4 @SiO 2 @Ag microflowers) were rationally designed and prepared to achieve strong bactericidal ability, a wide antimicrobial spectrum, and good recyclability. High-performance Fe 3 O 4 @SiO 2 @Ag microflowers served as a multifunction-supporting matrix and exhibited sufficient magnetic response property due to their 200 nm Fe 3 O 4 core. The microflowers also possessed a highly branched flower-like Ag shell that provided a large surface area for effective Ag ion release and bacterial contact. The modified-vancomycin layer was effectively bound to the cell wall of bacteria to increase the permeability of the cell membrane and facilitate the entry of the Ag ions into the bacterium, resulting in cell death. As such, the fabricated Van/Fe 3 O 4 @SiO 2 @Ag microflowers were predicted to be an effective and environment-friendly antibacterial agent. This hypothesis was verified through sterilization of Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus , with minimum inhibitory concentrations of 10 and 20 μg mL -1 , respectively. The microflowers also showed enhanced effect compared with bare Fe 3 O 4 @SiO 2 @Ag microflowers and free-form vancomycin, confirming the synergistic effects of the combination of the two components. Moreover, the antimicrobial effect was maintained at more than 90% after five cycling assays, indicating the high stability of the product. These findings reveal that Van/Fe 3 O 4 @SiO 2 @Ag microflowers exhibit promising applications in the antibacterial fields.

Consensus summary of aerosolized antimicrobial agents: application of guideline criteria. Insights from the Society of Infectious Diseases Pharmacists.

PubMed

Le, Jennifer; Ashley, Elizabeth Dodds; Neuhauser, Melinda M; Brown, Jack; Gentry, Chris; Klepser, Michael E; Marr, Ann Marie; Schiller, Daryl; Schwiesow, Joshua N; Tice, Sally; VandenBussche, Heather L; Wood, G Christopher

2010-06-01

Aerosolized delivery of antimicrobial agents is an attractive option for management of pulmonary infections, as this is an ideal method of providing high local drug concentrations while minimizing systemic exposure. With the paucity of consensus regarding the safety, efficacy, and means with which to use aerosolized antimicrobials, a task force was created by the Society of Infectious Diseases Pharmacists to critically review and evaluate the literature on the use of aerosolized antiinfective agents. This article summarizes key findings and statements for preventing or treating a variety of infectious diseases, including cystic fibrosis, bronchiecstasis, hospital-acquired pneumonia, fungal infections, nontuberculosis mycobacterial infection, and Pneumocystis jiroveci pneumonia. Our intention was to provide guidance for clinicians on the use of aerosolized antibiotics through evidence-based pharmacotherapy. Further research with well-designed clinical trials is necessary to elucidate the optimal dosage and duration of therapy and, of equal importance, to appreciate the true risks associated with the use of aerosolized delivery systems.

Screening of commercial and pecan shell-extracted liquid smoke agents as natural antimicrobials against foodborne pathogens.

PubMed

Van Loo, Ellen J; Babu, D; Crandall, Philip G; Ricke, Steven C

2012-06-01

Liquid smoke extracts have traditionally been used as flavoring agents, are known to possess antioxidant properties, and serve as natural alternatives to conventional antimicrobials. The antimicrobial efficacies of commercial liquid smoke samples may vary depending on their source and composition and the methods used to extract and concentrate the smoke. We investigated the MICs of eight commercial liquid smoke samples against Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli . The commercial liquid smoke samples purchased were supplied by the manufacturer as water-based or concentrated extracts of smoke from different wood sources. The MICs of the commercial smokes to inhibit the growth of foodborne pathogens ranged from 0.5 to 6.0% for E. coli, 0.5 to 8.0% for Salmonella, and 0.38 to 6% for S. aureus. The MIC for each liquid smoke sample was similar in its effect on both E. coli and Salmonella. Solvent-extracted antimicrobials prepared using pecan shells displayed significant differences between their inhibitory concentrations depending on the type of solvent used for extraction. The results indicated that the liquid smoke samples tested in this study could serve as effective natural antimicrobials and that their inhibitory effects depended more on the solvents used for extraction than the wood source.

Novel aminohydrazide cross-linked chitosan filled with multi-walled carbon nanotubes as antimicrobial agents.

PubMed

Mohamed, Nadia A; Abd El-Ghany, Nahed A

2018-04-21

Four chemically modified chitosan derivatives 1-4 were designed and synthesized via a series of four reactions; first by reaction with benzaldehyde to protect its amino groups (Derivative 1), second by reaction with epichlorohydrine (Derivative 2), third by reaction with aminobenzhydrazide (Derivative 3), and forth by removing of benzaldehyde to restore the free amino groups on the chitosan (Derivative 4). Two multi-walled carbon nanotube (MWCNT) biocomposites based on Derivative 4 were also prepared. The structure of the prepared derivatives and MWCNT composites was elucidated using elemental analyses, FTIR, XRD, SEM and TEM. The modified chitosan derivatives and MWCNT composites showed better antimicrobial activities than that of chitosan against Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Aspergillus niger, Cryptococcus neoformans and Candida tropicalis as judged by their higher inhibition zone diameters using the agar well diffusion technique. These derivatives and MWCNT composites are more potent against Gram-positive bacteria than against Gram-negative bacteria. The MWCNT composites displayed comparable or even better antimicrobial activities than the reference bactericides or fungicides. Thus, structural modification of chitosan through combination with functionalized moieties and MWCNTs in one system was taken as a way to achieve promising templates for antimicrobial agents and to be appropriate candidates for medical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Rhamnolipids as emulsifying agents for essential oil formulations: antimicrobial effect against Candida albicans and methicillin-resistant Staphylococcus aureus.

PubMed

Haba, Ester; Bouhdid, Samira; Torrego-Solana, Noelia; Marqués, A M; Espuny, M José; García-Celma, M José; Manresa, Angeles

2014-12-10

This work examines the influence of essential oil composition on emulsification with rhamnolipids and their use as therapeutic antimicrobial agents against two opportunistic pathogens, methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans. Rhamnolipids, produced by Pseudomonas aeruginosa, with waste frying oil as the carbon source, were composed of eight rhamnolipid homologues. The rhamnolipid mixture was used to produce emulsions containing essential oils (EOs) of Melaleuca alternifolia, Cinnamomum verum, Origanum compactum and Lavandula angustifolia using the titration method. Ternary phase diagrams were designed to evaluate emulsion stability, which differed depending on the essential oil. The in vitro antimicrobial activity of the EOs alone and the emulsions was evaluated. The antimicrobial activity presented by the essential oils alone increased with emulsification. The surface properties of rhamnolipids contribute to the positive dispersion of EOs and thus increase their availability and antimicrobial activity against C. albicans and S. aureus. Therefore, rhamnolipid-based emulsions represent a promising approach to the development of EO delivery systems. Copyright © 2014 Elsevier B.V. All rights reserved.

In vivo killing of Staphylococcus aureus using a light-activated antimicrobial agent

PubMed Central

2009-01-01

Background The widespread problem of antibiotic resistance in pathogens such as Staphylococcus aureus has prompted the search for new antimicrobial approaches. In this study we report for the first time the use of a light-activated antimicrobial agent, methylene blue, to kill an epidemic methicillin-resistant Staphylococcus aureus (EMRSA-16) strain in two mouse wound models. Results Following irradiation of wounds with 360 J/cm2 of laser light (670 nm) in the presence of 100 μg/ml of methylene blue, a 25-fold reduction in the number of viable EMRSA was seen. This was independent of the increase in temperature of the wounds associated with the treatment. Histological examination of the wounds revealed no difference between the photodynamic therapy (PDT)-treated wounds and the untreated wounds, all of which showed the same degree of inflammatory infiltration at 24 hours. Conclusion The results of this study demonstrate that PDT is effective at reducing the total number of viable EMRSA in a wound. This approach has promise as a means of treating wound infections caused by antibiotic-resistant microbes as well as for the elimination of such organisms from carriage sites. PMID:19193212

Antimicrobial Approaches for Textiles: From Research to Market

PubMed Central

Morais, Diana Santos; Guedes, Rui Miranda; Lopes, Maria Ascensão

2016-01-01

The large surface area and ability to retain moisture of textile structures enable microorganisms’ growth, which causes a range of undesirable effects, not only on the textile itself, but also on the user. Due to the public health awareness of the pathogenic effects on personal hygiene and associated health risks, over the last few years, intensive research has been promoted in order to minimize microbes’ growth on textiles. Therefore, to impart an antimicrobial ability to textiles, different approaches have been studied, being mainly divided into the inclusion of antimicrobial agents in the textile polymeric fibers or their grafting onto the polymer surface. Regarding the antimicrobial agents, different types have been used, such as quaternary ammonium compounds, triclosan, metal salts, polybiguanides or even natural polymers. Any antimicrobial treatment performed on a textile, besides being efficient against microorganisms, must be non-toxic to the consumer and to the environment. This review mainly intends to provide an overview of antimicrobial agents and treatments that can be performed to produce antimicrobial textiles, using chemical or physical approaches, which are under development or already commercially available in the form of isolated agents or textile fibers or fabrics. PMID:28773619

Methods of Antimicrobial Coating of Diverse Materials

NASA Technical Reports Server (NTRS)

Akse, James R.; Holtsnider, John T.; Kliestik, Helen

2011-01-01

Methods of coating diverse substrate materials with antimicrobial agents have been developed. Originally intended to reduce health risks to astronauts posed by pathogenic microorganisms that can grow on surfaces in spacecraft, these methods could also be used on Earth for example, to ensure sterility of surgical inserts and other medical equipment. The methods involve, generally, chemical preparation of substrate surfaces to enable attachment of antimicrobial molecules to the substrate surfaces via covalent bonds. Substrate materials that have been treated successfully include aluminum, glass, a corrosion-resistant nickel alloy, stainless steel, titanium, and poly(tetrafluoroethylene). Antimicrobial agents that have been successfully immobilized include antibiotics, enzymes, bacteriocins, bactericides, and fungicides. A variety of linkage chem istries were employed. Activity of antimicrobial coatings against gram-positive bacteria, gram-negative bacteria, and fungi was demonstrated. Results of investigations indicate that the most suitable combination of antimicrobial agent, substrate, and coating method depends upon the intended application.

Design, synthesis and biological evaluation of 5-fluorouracil-derived benzimidazoles as novel type of potential antimicrobial agents.

PubMed

Fang, Xue-Jie; Jeyakkumar, Ponmani; Avula, Srinivasa Rao; Zhou, Qian; Zhou, Cheng-He

2016-06-01

A series of 5-fluorouracil benzimidazoles as novel type of potential antimicrobial agents were designed and synthesized for the first time. Bioactive assay manifested that some of the prepared compounds exhibited good or even stronger antibacterial and antifungal activities against the tested strains in comparison with reference drugs norfloxacin, chloromycin and fluconazole. Noticeably, 3-fluorobenzyl benzimidazole derivative 5c gave remarkable antimicrobial activities against Saccharomyces cerevisiae, MRSA and Bacillus proteus with MIC values of 1, 2 and 4μg/mL, respectively. Experimental research revealed that compound 5c could effectively intercalate into calf thymus DNA to form compound 5c-DNA complex which might block DNA replication and thus exert antimicrobial activities. Molecular docking indicated that compound 5c should bind with DNA topoisomerase IA through three hydrogen bonds by the use of fluorine atom and oxygen atoms in 5-fluorouracil with the residue Lys 423. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of silver-copper core-shell nanoparticles using polyol method for antimicrobial agent

NASA Astrophysics Data System (ADS)

Hikmah, N.; Idrus, N. F.; Jai, J.; Hadi, A.

2016-06-01

Silver and copper nanoparticles are well-known as the good antimicrobial agent. The nano-size of particles influences in enhancing the antimicrobial activity. This paper discusses the effect of molarity on the microstructure and morphology of silver-copper core-shell nanoparticles prepared by a polyol method. In this study, silver-copper nanoparticles are synthesized through the green approach of polyol method using ethylene glycol (EG) as green solvent and reductant, and polyoxyethylene-(80)-sorbitan monooleate (Tween 80) as a nontoxic stabilizer. The phase and morphology of silver-copper nanoparticles are characterized by X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM) and Transmission electron microscope (TEM). The results XRD confirm the pure crystalline of silver and copper nanoparticles with face-centered cubic (FCC) structure. FESEM and TEM analysis confirm the existence of Ag and Cu nanoparticles in core-shell shape.

ZnO and TiO2 nanoparticles as novel antimicrobial agents for oral hygiene: a review

NASA Astrophysics Data System (ADS)

Khan, Shams Tabrez; Al-Khedhairy, Abdulaziz A.; Musarrat, Javed

2015-06-01

Oral cavity is inhabited by more than 25,000 different bacterial phylotypes; some of them cause systemic infections in addition to dental and periodontal diseases. Emergence of multiple antibiotic resistance among these bacteria necessitates the development of alternative antimicrobial agents that are safe, stable, and relatively economic. This review focuses on the significance of metal oxide nanoparticles, especially zinc oxide and titanium dioxide nanoparticles as supplementary antimicrobials for controlling oral infections and biofilm formation. Indeed, the ZnO NPs and TiO2 NPs have exhibited significant antimicrobial activity against oral bacteria at concentrations which is not toxic in in vivo toxicity assays. These nanoparticles are being produced at an industrial scale for use in a variety of commercial products including food products. Thus, the application of ZnO and TiO2 NPs as nanoantibiotics for the development of mouthwashes, dental pastes, and other oral hygiene materials is envisaged. It is also suggested that these NPs could serve as healthier, innocuous, and effective alternative for controlling both the dental biofilms and oral planktonic bacteria with lesser side effects and antibiotic resistance.

Short AntiMicrobial Peptides (SAMPs) as a class of extraordinary promising therapeutic agents.

PubMed

Ramesh, Suhas; Govender, Thavendran; Kruger, Hendrik G; de la Torre, Beatriz G; Albericio, Fernando

2016-07-01

The emergence of multidrug resistant bacteria has a direct impact on global public health because of the reduced potency of existing antibiotics against pathogens. Hence, there is a pressing need for new drugs with different modes of action that can kill microorganisms. Antimicrobial peptides (AMPs) can be regarded as an alternative tool for this purpose because they are proven to have therapeutic effects with broad-spectrum activities. There are some hurdles in using AMPs as clinical candidates such as toxicity, lack of stability and high budgets required for manufacturing. This can be overcome by developing shorter and more easily accessible AMPs, the so-called Short AntiMicrobial Peptides (SAMPs) that contain between two and ten amino acid residues. These are emerging as an attractive class of therapeutic agents with high potential for clinical use and possessing multifunctional activities. In this review we attempted to compile those SAMPs that have exhibited biological properties which are believed to hold promise for the future. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

[Studies on antimicrobial activity of extracts from thyme].

PubMed

Fan, M; Chen, J

2001-08-01

The extracts from thyme by water and ethanol, thyme essential oil, thymol and carvacrol were used as antimicrobial agents in this paper. The results show that all antimicrobial agents used have strong inhibition activity against Staphalococcus aureus, Bacillus subtilis, Escherichia coli.

[Kinetics of decamethoxine, an antimicrobial agent].

PubMed

Paliĭ, G K; Nazarchuk, A A; Kulakov, A I; Nazarchuk, G G; Paliĭ, D V; Bereza, B N; Oleĭnik, D P

2014-01-01

The kinetics of decamethoxine liberation from medical antimicrobial textiles was studied. The elution of decamethoxine was shown to be a complicated diffusive-kinetic process dependent on the exposure and concentration of decamethoxine.

Vancomycin-modified Fe3O4@SiO2@Ag microflowers as effective antimicrobial agents

PubMed Central

Wang, Chongwen; Zhang, Kehan; Zhou, Zhe; Li, Qingjun; Shao, Liting; Hao, Rong Zhang; Xiao, Rui; Wang, Shengqi

2017-01-01

Nanomaterials combined with antibiotics exhibit synergistic effects and have gained increasing interest as promising antimicrobial agents. In this study, vancomycin-modified magnetic-based silver microflowers (Van/Fe3O4@SiO2@Ag microflowers) were rationally designed and prepared to achieve strong bactericidal ability, a wide antimicrobial spectrum, and good recyclability. High-performance Fe3O4@SiO2@Ag microflowers served as a multifunction-supporting matrix and exhibited sufficient magnetic response property due to their 200 nm Fe3O4 core. The microflowers also possessed a highly branched flower-like Ag shell that provided a large surface area for effective Ag ion release and bacterial contact. The modified-vancomycin layer was effectively bound to the cell wall of bacteria to increase the permeability of the cell membrane and facilitate the entry of the Ag ions into the bacterium, resulting in cell death. As such, the fabricated Van/Fe3O4@SiO2@Ag microflowers were predicted to be an effective and environment-friendly antibacterial agent. This hypothesis was verified through sterilization of Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus, with minimum inhibitory concentrations of 10 and 20 μg mL−1, respectively. The microflowers also showed enhanced effect compared with bare Fe3O4@SiO2@Ag microflowers and free-form vancomycin, confirming the synergistic effects of the combination of the two components. Moreover, the antimicrobial effect was maintained at more than 90% after five cycling assays, indicating the high stability of the product. These findings reveal that Van/Fe3O4@SiO2@Ag microflowers exhibit promising applications in the antibacterial fields. PMID:28450783

Genotypic Analysis of Escherichia coli Strains from Poultry Carcasses and Their Susceptibilities to Antimicrobial Agents

PubMed Central

Geornaras, Ifigenia; Hastings, John W.; von Holy, Alexander

2001-01-01

Plasmid profiling and amplified fragment length polymorphism (AFLP) analysis were used to genotype 50 Escherichia coli strains from poultry carcasses. Thirty different plasmid profiles were evident, and clustering of the AFLP data showed that they were a distinctly heterogeneous group of strains. Susceptibility testing against five antimicrobial agents used in the South African poultry industry showed all strains to be susceptible to danofloxacin and colistin, while the majority (96%) were resistant to two tetracyclines. PMID:11282652

Antimicrobial Tolerance in Biofilms

PubMed Central

Stewart, Philip S.

2015-01-01

The tolerance of microorganisms in biofilms to antimicrobial agents is examined through a meta-analysis of literature data. A numerical tolerance factor comparing the rates of killing in the planktonic and biofilm states is defined to provide a quantitative basis for the analysis. Tolerance factors for biocides and antibiotics range over three orders of magnitude. This variation is not explained by taking into account the molecular weight of the agent, the chemistry of the agent, the substratum material, or the speciation of the microorganisms. Tolerance factors do depend on the areal cell density of the biofilm at the time of treatment and on the age of the biofilm as grown in a particular experimental system. This suggests that there is something that happens during biofilm maturation, either physical or physiological, that is essential for full biofilm tolerance. Experimental measurements of antimicrobial penetration times in biofilms range over orders of magnitude, with slower penetration (>12 min) observed for reactive oxidants and cationic molecules. These agents are retarded through the interaction of reaction, sorption, and diffusion. The specific physiological status of microbial cells in a biofilm contributes to antimicrobial tolerance. A conceptual framework for categorizing physiological cell states is discussed in the context of antimicrobial susceptibility. It is likely that biofilms harbor cells in multiple states simultaneously (e.g., growing, stress-adapted, dormant, inactive) and that this physiological heterogeneity is an important factor in the tolerance of the biofilm state. PMID:26185072

Cationic antimicrobial polymers and their assemblies.

PubMed

Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

2013-05-10

Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

Cationic Antimicrobial Polymers and Their Assemblies

PubMed Central

Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

2013-01-01

Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications. PMID:23665898

Mushrooms as possible antioxidant and antimicrobial agents.

PubMed

Kosanić, Marijana; Ranković, Branislav; Dašić, Marko

2012-01-01

The aim of the study is to examine in-vitro antioxidant and antimicrobial activity of the acetonic and methanolic extracts of the mushrooms Boletus aestivalis, Boletus edulis and Leccinum carpini. Antioxidant activity was evaluated by using free radical scavenging activity and reducing power. In addition, total content of phenol and flavonoid in extracts were determined as pyrocatechol equivalent, and as rutin equivalent, respectively. As a result of the study acetonic extracts from Boletus edulis was more powerful antioxidant activity with IC50 value of 4.72 μg/mL which was similar or greater than the standard antioxidants, ascorbic acid (IC50 = 4.22 μg/mL), BHA (IC50 = 6.42 μg/mL) and α-tocopherol (IC50 = 62.43 μg/mL). Moreover, the tested extracts had effective reducing power. A significant relationship between total phenolic and flavonoid contents and their antioxidative activities was significantly observed. The antimicrobial activity of each extract was estimated by determination of the minimum inhibitory concentration by using microdilution plate method against five species of bacteria and five species of fungi. Generally, the tested mushroom extracts had relatively strong antimicrobial activity against the tested microorganisms. The minimum inhibitory concentration for both extracts related to the tested bacteria and fungi were 1.25 - 10 mg/ mL. The present study shows that tested mushroom species demonstrated a strong antioxidant and antimicrobial activity. It suggests that mushroom may be used as good sources of natural antioxidants and for pharmaceutical purposes in treating of various deseases.

Mushrooms as Possible Antioxidant and Antimicrobial Agents

PubMed Central

Kosanić, Marijana; Ranković, Branislav; Dašić, Marko

2012-01-01

The aim of the study is to examine in-vitro antioxidant and antimicrobial activity of the acetonic and methanolic extracts of the mushrooms Boletus aestivalis, Boletus edulis and Leccinum carpini. Antioxidant activity was evaluated by using free radical scavenging activity and reducing power. In addition, total content of phenol and flavonoid in extracts were determined as pyrocatechol equivalent, and as rutin equivalent, respectively. As a result of the study acetonic extracts from Boletus edulis was more powerful antioxidant activity with IC50 value of 4.72 μg/mL which was similar or greater than the standard antioxidants, ascorbic acid (IC50 = 4.22 μg/mL), BHA (IC50 = 6.42 μg/mL) and α-tocopherol (IC50 = 62.43 μg/mL). Moreover, the tested extracts had effective reducing power. A significant relationship between total phenolic and flavonoid contents and their antioxidative activities was significantly observed. The antimicrobial activity of each extract was estimated by determination of the minimum inhibitory concentration by using microdilution plate method against five species of bacteria and five species of fungi. Generally, the tested mushroom extracts had relatively strong antimicrobial activity against the tested microorganisms. The minimum inhibitory concentration for both extracts related to the tested bacteria and fungi were 1.25 - 10 mg/ mL. The present study shows that tested mushroom species demonstrated a strong antioxidant and antimicrobial activity. It suggests that mushroom may be used as good sources of natural antioxidants and for pharmaceutical purposes in treating of various deseases. PMID:24250542

A 3D Hydrodynamic Model for Heterogeneous Biofilms with Antimicrobial Persistence

DTIC Science & Technology

2014-01-01

antimicrobial agents, providing a useful tool for analyzing the mechanism of biofilm persistence to antimicrobial agents in an aqueous environment. The numerical...mecha- nism of biofilm persistence to antimicrobial agents in an aqueous environment. The numerical result also confirms that the periodic dosing...We model the biofilm together with its surrounding aqueous environment as a mixture of complex fluids. The biofilm is consisted of the biomass

Alginate edible films containing microencapsulated lemongrass oil or citral: effect of encapsulating agent and storage time on physical and antimicrobial properties.

PubMed

Alarcón-Moyano, Jessica K; Bustos, Rubén O; Herrera, María Lidia; Matiacevich, Silvia B

2017-08-01

Active edible films have been proposed as an alternative to extend shelf life of fresh foods. Most essential oils have antimicrobial properties; however, storage conditions could reduce their activity. To avoid this effect the essential oil (EO) can be microencapsulated prior to film casting. The aim of this study was to determine the effects of the type of encapsulating agent (EA), type of EO and storage time on physical properties and antimicrobial activity of alginate-based films against Escherichia coli ATCC 25922. Trehalose (TH), Capsul ® (CAP) and Tween 20 (Tw20) were used as EA. Lemongrass essential oil (LMO) and citral were used as active agents. The results showed that the type of EA affected the stability of the film forming-emulsions as well as the changes in opacity and colour of the films during storage but not the antimicrobial activity of them. Both microencapsulated EOs showed a prolonged release from the alginate films during the 28 days of storage. Trehalose was selected to encapsulate both active compounds because the films made with this microencapsulated EA showed the greatest physical stability and the lowest color variation among all the films studied.

pH Dependent Antimicrobial Peptides and Proteins, Their Mechanisms of Action and Potential as Therapeutic Agents

PubMed Central

Malik, Erum; Dennison, Sarah R.; Harris, Frederick; Phoenix, David A.

2016-01-01

delivery systems. Nonetheless, many pH dependent AMPs and antimicrobial proteins have yet to be fully characterized and these molecules, as a whole, represent an untapped source of novel biologically active agents that could aid fulfillment of the urgent need for alternatives to conventional antibiotics, helping to avert a return to the pre-antibiotic era. PMID:27809281

KR-12-a5 is a non-cytotoxic agent with potent antimicrobial effects against oral pathogens.

PubMed

Caiaffa, Karina Sampaio; Massunari, Loiane; Danelon, Marcelle; Abuna, Gabriel Flores; Bedran, Telma Blanca Lombardo; Santos-Filho, Norival Alves; Spolidorio, Denise Madalena Palomari; Vizoto, Natalia Leal; Cilli, Eduardo Maffud; Duque, Cristiane

2017-11-01

This study evaluated the cytotoxicity and antimicrobial activity of analogs of cationic peptides against microorganisms associated with endodontic infections. L-929 fibroblasts were exposed to LL-37, KR-12-a5 and hBD-3-1C V and chlorhexidine (CHX, control), and cell metabolism was evaluated with MTT. The minimal inhibitory concentration (MIC) and the minimal bactericidal/fungicidal concentration (MBC/MFC) of the peptides and CHX were determined against oral pathogens associated with endodontic infections. Enterococcus faecalis and Streptococcus mutans biofilms were cultivated in bovine dentin blocks, exposed to different concentrations of the most efficient antimicrobial peptide and analyzed by confocal laser scanning microscopy. CHX and peptides affected the metabolism of L-929 at concentrations > 31.25 and 500 μg ml -1 , respectively. Among the peptides, KR-12-a5 inhibited growth of both the microorganisms tested with the lowest MIC/MBC/MFC values. In addition, KR-12-a5 significantly reduced E. faecalis and S. mutans biofilms inside dentin tubules. In conclusion, KR-12-a5 is a non-cytotoxic agent with potent antimicrobial and anti-biofilm activity against oral pathogens associated with endodontic infections.

Antimicrobial agents from selected medicinal plants in Libya.

PubMed

Muhaisen, Hasan M H; Ab-Mous, Miftah Mailoud; Ddeeb, Fadel A; Rtemi, Aboclaid Ali; Taba, Omer M; Parveen, Mehtab

2016-03-01

To test the in vitro antimicrobial efficacy of water and methanol extracts of 23 plant species that are commonly used in Libyan folk medicine. The antimicrobial activity was determined using the well-diffusion method. Four test microorganisms were used namely, Escherichia coli, Salmonella species, Staphylococcus aureus and Bacillus subtilis. The minimum inhibitory concentration (MIC) was determined for the high biologically active crude plant extracts. Among 23 medicinal plants used in the study, only 5 methanolic extracts [Rosmarinus offcinalis L., Carduus marianium L., Lantana camara L., Rhus tripartite (ueria) Grande, and Thymus capitatus (L.) Hoffm (link)] showed the highest antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Salmonella species, while 22 methanolic and aqueous extracts showed moderate to weak antimicrobial activity on all tested organisms. However 19 of the extracts showed no activity at all against Gram-ve and Gram +ve microorganisms. MIC was found to be 1.25 mg/mL (Thymus capitatus), 3 mg/mL (Rhus tripartite), 4 mg/mL (Carduus marianium), 5 mg/mL (Rosamarinus officinalis) and 5 mg/mL (Lantana camara), respectively. The present results revealed that, crude methanolic extracts of the investigated Libyan folk medicinal plants exhibited mild to high in vitro antibacterial activities against Gram-positive and Gram-negative microorganisms.

Urinary tract infection in pregnant population, which empirical antimicrobial agent should be specified in each of the three trimesters?

PubMed

Unlu, Bekir Serdar; Yildiz, Yunus; Keles, Ibrahim; Kaba, Metin; Kara, Halil; Tasin, Cuma; Erkilinc, Selcuk; Yildirim, Gulcin

2014-05-01

We aimed to investigate the bacterial profile and the adequacy of antimicrobial treatment in pregnant women with urinary tract infection. This retrospective observational study was conducted with 753 pregnant women who needed hospitalization because of UTI in each of the three trimesters. Midstream urine culture and antimicrobial susceptibility tests were evaluated. E. Coli was the most frequently isolated bacterial agent (82.2%), followed by Klebsiella spp. (11.2%). In each of the three trimesters, E. Coli remained the most frequently isolated bacterium (86%, 82.2%, 79.5%, respectively), followed by Klebsiella spp. (9%, 11.6%, 12.2%, respectively). Enterococcus spp. were isolated as a third microbial agent, with 43 patients (5.7%) in the three trimesters. The bacteria were found to be highly sensitive to fosfomycin, with 98-99% sensitivity for E.Coli and 88-89% for Klebsiella spp. and for Enterococcus spp. 93-100% nitrofurantoin sensitivity for each of the three trimesters. We demonstrated that E. Coli and Klebsiella spp. are the most common bacterial agents isolated from urine culture of pregnant women with UTI in each of the three trimesters. We consider fosfomycin to be the most adequate first-line treatment regimen due to high sensitivity to the drug, ease of use and safety for use in pregnancy

Microwave Assisted Synthesis of 1-[5-(Substituted Aryl)-1H-Pyrazol-3-yl]-3,5-Diphenyl-1H-1,2,4-Triazole as Antinociceptive and Antimicrobial Agents

PubMed Central

Khanage, Shantaram Gajanan; Mohite, Popat Baban; Pandhare, Ramdas Bhanudas; Raju, S. Appala

2014-01-01

Purpose: An efficient technique has been developed for microwave assisted synthesis of 1-[5-(substituted aryl)-1H-pyrazol-3-yl]-3,5-diphenyl-1H-1,2,4-triazole as antinociceptive and antimicrobial agents. Methods: The desired compounds (S1-S10) were synthesized by the microwave irradiation via cyclization of formerly synthesized chalcones of 3,5-diphenyl-1H-1,2,4-triazole and hydrazine hydrate in mild acidic condition. All newly synthesized compounds were subjected to study their antinociceptive and antimicrobial activity. The analgesic potential of compounds was tested by acetic acid induced writhing response and hot plate method. The MIC values for antimicrobial activity were premeditated by liquid broth method. Results: The compounds S1, S2, S4, S6 and S10 were found to be excellent peripherally acting analgesic agents when tested on mice by acetic acid induced writhing method and compounds S3, S6 and S1 at dose level of 100 mg/kg were exhibited superior centrally acting antinociceptive activity when tested by Eddy’s hot plate method. In antimicrobial activity compound S10 found to be broad spectrum antibacterial agent at MIC value of 15.62 µg/ml and compound S6 was exhibited antifungal potential at 15.62 µg/mL on both fungal strains. Conclusion: Some novel pyrazoles clubbed with 1,2,4-triazole derivatives were synthesized and evaluated as possible antimicrobial, centrally and peripherally acting analgesics. PMID:24511473

Shelf-life extension of gilthead seabream fillets by osmotic treatment and antimicrobial agents.

PubMed

Tsironi, T N; Taoukis, P S

2012-02-01

The objectives of the study were to evaluate the effect of selected antimicrobial agents on the shelf life of osmotically pretreated gilthead seabream and to establish reliable kinetic equations for shelf-life determination validated in dynamic conditions. Fresh gilthead seabream (Sparus aurata) fillets were osmotically treated with 50% high dextrose equivalent maltodextrin (HDM, DE 47) plus 5% NaCl and 0·5% carvacrol, 0·5% glucono-δ-lactone or 1% Citrox (commercial antimicrobial mix). Untreated and treated slices were aerobically packed and stored isothermally (0-15°C). Microbial growth and quality-related chemical indices were modelled as functions of temperature. Models were validated at dynamic storage conditions. Osmotic pretreatment with the use of antimicrobials led to significant shelf-life extension of fillets, in terms of microbial growth and organoleptic deterioration. The shelf life was 7 days for control samples at 5°C. The osmotic pretreatment with carvacrol, glucono-δ-lactone and Citrox allowed for shelf-life extension by 8, 10 and 5 days at 5°C, respectively. The results of the study show the potential of adding carvacrol, glucono-δ-lactone or Citrox in the osmotic solution to extend the shelf life and improve commercial value of chilled osmotically pretreated fish products. The developed models can be a reliable tool for predicting the shelf life of fresh or minimally processed gilthead seabream fillets in the real chill chain. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Properties and applications of antimicrobial peptides in biodefense against biological warfare threat agents.

PubMed

Dawson, Raymond Murray; Liu, Chun-Qiang

2008-01-01

Recent advances in knowledge of the properties of antimicrobial peptides (AMPs) are reviewed. AMPs are typically small, positively charged, amphipathic peptides that interact electrostatically and non-stereospecifically with the bacterial cell membrane, resulting in its permeabilization and cell death. Classes of AMPs, their mechanisms of action, hemolytic activity, and cytotoxicity towards host cells are discussed. A particular focus is AMPs with potential for use in defense against biological warfare agents. Some AMPs cytotoxic to Bacillus anthracis have been described. Synthesis of these peptides in multivalent form leads to a synergistic increase in antibacterial activity. Strategies to enhance the potency, stability, and selectivity of AMPs are discussed.

An oral carbapenem, but only now intravenous penicillin: the paradox of Japanese antimicrobials.

PubMed

Rogers, Benjamin A; Hayashi, Yoshiro

2012-12-01

At present there is a profound paradox in antimicrobial use and development in Japan. A tightly held domestic pharmaceutical market with significant barriers to the importation and registration of foreign agents, has spurred domestic pharmaceutical companies to develop a vast range of antimicrobials. Many Japanese developed antimicrobials are now used globally. A negative consequence of this environment, however, is the lack of availability of several 'workhorse' narrow-spectrum agents to treat patients in Japan. Absent agents include anti-staphylococcal penicillins and until recently, intravenous benzylpenicillin. In substitution for these unavailable agents, patients are frequently administered broader spectrum antimicrobials. This change offers no additional benefit to the patient and is potentially contributing to treatment failure and high rates of antimicrobial resistance amongst key bacterial pathogens in Japan. The situation in Japan illustrates the broader global challenges faced in integrating the development of new antimicrobial agents with maintaining the supply and use of older and less profitable agents. Copyright © 2012 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Spectrum of antimicrobial activity associated with ionic colloidal silver.

PubMed

Morrill, Kira; May, Kathleen; Leek, Daniel; Langland, Nicole; Jeane, La Deana; Ventura, Jose; Skubisz, Corey; Scherer, Sean; Lopez, Eric; Crocker, Ephraim; Peters, Rachel; Oertle, John; Nguyen, Krystine; Just, Scott; Orian, Michael; Humphrey, Meaghan; Payne, David; Jacobs, Bertram; Waters, Robert; Langland, Jeffrey

2013-03-01

Silver has historically and extensively been used as a broad-spectrum antimicrobial agent. However, the Food and Drug Administration currently does not recognize colloidal silver as a safe and effective antimicrobial agent. The goal of this study was to further evaluate the antimicrobial efficacy of colloidal silver. Several strains of bacteria, fungi, and viruses were grown under multicycle growth conditions in the presence or absence of ionic colloidal silver in order to assess the antimicrobial activity. For bacteria grown under aerobic or anaerobic conditions, significant growth inhibition was observed, although multiple treatments were typically required. For fungal cultures, the effects of ionic colloidal silver varied significantly between different genera. No viral growth inhibition was observed with any strains tested. The study data support ionic colloidal silver as a broad-spectrum antimicrobial agent against aerobic and anaerobic bacteria, while having a more limited and specific spectrum of activity against fungi.

Does release of antimicrobial agents from impregnated external ventricular drainage catheters affect the diagnosis of ventriculitis?

PubMed

Bayston, Roger; Ashraf, Waheed; Ortori, Catherine

2016-02-01

Recently concern has arisen over the effect of released antimicrobial agents from antibiotic-impregnated external ventricular drainage (EVD) catheters on the reliability of CSF culture for diagnosis of ventriculitis. The authors designed a laboratory study to investigate this possibility, and to determine whether there was also a risk of loss of bacterial viability when CSF samples were delayed in transport to the laboratory. Three types of commercially available antibiotic-impregnated EVD catheters were perfused with a suspension of bacteria (Staphylococcus epidermidis) over 21 days. Samples were analyzed for bacterial viability and for concentrations of antibiotics released from the catheters. The authors also investigated the effect on bacterial viability in samples stored at 18°C and 4°C to simulate delay in CSF samples reaching the laboratory for analysis. Bacterial viability was significantly reduced in all 3 catheter types when sampled on Day 1, but this effect was not observed in later samples. The results were reflected in stored samples, with significant loss of viability in Day 1 samples but with little further loss of viable bacteria in samples obtained after this time point. All samples stored for 18 hours showed significant loss of viable bacteria. While there were differences between the catheters, only samples taken on Day 1 showed a significant reduction in the numbers of viable bacteria after passing through the catheters. This reduction coincided with higher concentrations of antimicrobial agents in the first few hours after perfusion began. Similarly, bacterial viability declined significantly after storage of Day 1 samples, but only slightly in samples obtained thereafter. The results indicate that drugs released from these antimicrobial catheters are unlikely to affect the diagnosis of ventriculitis, as sampling for this purpose is not usually conducted in the first 24 hours of EVD.

Multidrug resistant Salmonella enterica isolated from conventional pig farms using antimicrobial agents in preventative medicine programmes.

PubMed

Cameron-Veas, Karla; Fraile, Lorenzo; Napp, Sebastian; Garrido, Victoria; Grilló, María Jesús; Migura-Garcia, Lourdes

2018-04-01

A longitudinal study was conducted to investigate the presence of multidrug antimicrobial resistance (multi-AR) in Salmonella enterica in pigs reared under conventional preventative medicine programmes in Spain and the possible association of multi-AR with ceftiofur or tulathromycin treatment during the pre-weaning period. Groups of 7-day-old piglets were treated by intramuscular injection with ceftiofur on four farms (n=40 piglets per farm) and with tulathromycin on another four farms (n=40 piglets per farm). A control group of untreated piglets (n=30 per farm) was present on each farm. Faecal swabs were collected for S. enterica culture prior to treatment, at 2, 7 and 180days post-treatment, and at slaughter. Minimal inhibitory concentrations of 14 antimicrobial agents, pulsed-field gel electrophoresis and detection of resistance genes representing five families of antimicrobial agents were performed. Plasmids carrying cephalosporin resistant (CR) genes were characterised. Sixty-six S. enterica isolates were recovered from five of eight farms. Forty-seven isolates were multi-AR and four contained bla CTX-M genes harboured in conjugative plasmids of the IncI1 family; three of these isolates were recovered before treatment with ceftiofur. The most frequent AR genes detected were tet(A) (51/66, 77%), sul1 (17/66, 26%); tet(B) (15/66, 23%) and qnrB (10/66, 15%). A direct relation between the use of ceftiofur in these conditions and the occurrence of CR S. enterica was not established. However, multi-AR was common, especially for ampicillin, streptomycin, sulphonamides and tetracycline. These antibiotics are used frequently in veterinary medicine in Spain and, therefore, should be used sparingly to minimise the spread of multi-AR. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Retainment of the antimicrobial agent triclosan in a septic tank.

PubMed

Kirjanova, Ala; Rimeika, Mindaugas; Vollertsen, Jes; Nielsen, Asbjørn Haaning

2014-01-01

Laboratory experiments were conducted to investigate the fate of the antimicrobial agent triclosan (TCS) in a conventional septic tank. The main mechanism of TCS removal from wastewater was identified to be rapid TCS sorption to suspended particles followed by settling of these particles to the bottom of the septic tank. Sorption to particles was completed within minutes while the settling took several days. Therefore, in a septic tank the removal of TCS from wastewater is mainly determined by the removal of suspended particles by sedimentation. Over 5 days of hydraulic residence time the initial dissolved TCS concentration of 100 μg L(-1) was reduced by 87 ± 8%. During the first 24 hours, 66-86% of all removed TCS was retained, whereas during the remainder of the experiment a slight but steady decrease in TCS concentration was observed. This was most likely caused by TCS diffusion and its subsequent sorption onto the septic sludge.

Helical Antimicrobial Sulfono- {gamma} -AApeptides

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

Li, Yaqiong; Wu, Haifan; Teng, Peng

Host-defense peptides (HDPs) such as magainin 2 have emerged as potential therapeutic agents combating antibiotic resistance. Inspired by their structures and mechanism of action, herein we report the fi rst example of antimicrobial helical sulfono- γ - AApeptide foldamers. The lead molecule displays broad-spectrum and potent antimicrobial activity against multi-drug-resistant Gram- positive and Gram-negative bacterial pathogens. Time-kill studies and fl uorescence microscopy suggest that sulfono- γ -AApeptides eradicate bacteria by taking a mode of action analogous to that of HDPs. Clear structure - function relationships exist in the studied sequences. Longer sequences, presumably adopting more-de fi ned helical structures, aremore » more potent than shorter ones. Interestingly, the sequence with less helical propensity in solution could be more selective than the stronger helix-forming sequences. Moreover, this class of antimicrobial agents are resistant to proteolytic degradation. These results may lead to the development of a new class of antimicrobial foldamers combating emerging antibiotic-resistant pathogens.« less

Chitosan-thioglycolic acid as a versatile antimicrobial agent.

PubMed

Geisberger, Georg; Gyenge, Emina Besic; Hinger, Doris; Käch, Andres; Maake, Caroline; Patzke, Greta R

2013-04-08

As functionalized chitosans hold great potential for the development of effective and broad-spectrum antibiotics, representative chitosan derivatives were tested for antimicrobial activity in neutral media: trimethyl chitosan (TMC), carboxy-methyl chitosan (CMC), and chitosan-thioglycolic acid (TGA; medium molecular weight: MMW-TGA; low molecular weight: LMW-TGA). Colony forming assays indicated that LMW-TGA displayed superior antimicrobial activity over the other derivatives tested: a 30 min incubation killed 100% Streptococcus sobrinus (Gram-positive bacteria) and reduced colony counts by 99.99% in Neisseria subflava (Gram-negative bacteria) and 99.97% in Candida albicans (fungi). To elucidate LMW-TGA effects at the cellular level, microscopic studies were performed. Use of fluorescein isothiocyanate (FITC)-labeled chitosan derivates in confocal microscopy showed that LMW-TGA attaches to microbial cell walls, while transmission electron microscopy indicated that this derivative severely affects cell wall integrity and intracellular ultrastructure in all species tested. We therefore propose LMW-TGA as a promising and effective broad-band antimicrobial compound.

Bionano Interaction Study on Antimicrobial Star-Shaped Peptide Polymer Nanoparticles.

PubMed

Lam, Shu J; Wong, Edgar H H; O'Brien-Simpson, Neil M; Pantarat, Namfon; Blencowe, Anton; Reynolds, Eric C; Qiao, Greg G

2016-12-14

'Structurally nanoengineered antimicrobial peptide polymers' (SNAPPs), in the form of star-shaped peptide polymer nanoparticles, have been recently demonstrated as a new class of antimicrobial agents with superior in vitro and in vivo efficacy against Gram-negative pathogens, including multidrug-resistant species. Herein, we present a detailed bionano interaction study on SNAPPs by assessing their antimicrobial activities against several Gram-negative bacteria in complex biological matrices. Simulated body fluid and animal serum were used as test media to reveal factors that influence the antimicrobial efficacy of SNAPPs. With the exception of Acinetobacter baumannii, the presence of divalent cations at physiological concentrations reduced the antimicrobial efficacy of SNAPPs from minimum inhibitory concentrations (MICs) within the nanomolar range (40-300 nM) against Escherichia coli, Pseudomanas aeruginosa, and Klebsiella pneumoniae to 0.6-4.7 μM. By using E. coli as a representative bacterial species, we demonstrated that the reduction in activity was due to a decrease in the ability of SNAPPs to cause outer and inner membrane disruption. This effect could be reversed through coadministration with a chelating agent. Interestingly, the potency of SNAPPs against A. baumannii was retained even under high salt concentrations. The presence of serum proteins was also found to affect the interaction of SNAPPs with bacterial membranes, possibly through intermolecular binding. Collectively, this study highlights the need to consider the possible interactions of (bio)molecules present in vivo with any new antimicrobial agent under development. We also demonstrate that outer membrane disruption/destabilization is an important but hitherto under-recognized target for the antimicrobial action of peptide-based agents, such as antimicrobial peptides (AMPs). Overall, the findings presented herein could aid in the design of more efficient peptide-based antimicrobial agents with

Susceptibilities of Haemophilus influenzae and Moraxella catarrhalis to ABT-773 Compared to Their Susceptibilities to 11 Other Agents

PubMed Central

Credito, Kim L.; Lin, Gengrong; Pankuch, Glenn A.; Bajaksouzian, Saralee; Jacobs, Michael R.; Appelbaum, Peter C.

2001-01-01

The activity of the ketolide ABT-773 against Haemophilus and Moraxella was compared to those of 11 other agents. Against 210 Haemophilus influenzae strains (39.0% β-lactamase positive), microbroth dilution tests showed that azithromycin and ABT-773 had the lowest MICs (0.5 to 4.0 and 1.0 to 8.0 μg/ml, respectively), followed by clarithromycin and roxithromycin (4.0 to >32.0 μg/ml). Of the β-lactams, ceftriaxone had the lowest MICs (≤0.004 to 0.016 μg/ml), followed by cefixime and cefpodoxime (0.008 to 0.125 and ≤0.125 to 0.25 μg/ml, respectively), amoxicillin-clavulanate (0.125 to 4.0 μg/ml), and cefuroxime (0.25 to 8.0 μg/ml). Amoxicillin was only active against β-lactamase-negative strains, and cefprozil had the highest MICs of all oral cephalosporins tested (0.5 to >32.0 μg/ml). Against 50 Moraxella catarrhalis strains, all of the compounds except amoxicillin and cefprozil were active. Time-kill studies against 10 H. influenzae strains showed that ABT-773, at two times the MIC, was bactericidal against 9 of 10 strains, with 99% killing of all strains at the MIC after 24 h; at 12 h, ABT-773 gave 90% killing of all strains at two times the MIC. At 3 and 6 h, killing by ABT-773 was slower, with 99.9% killing of four strains at two times the MIC after 6 h. Similar results were found for azithromycin, with slightly slower killing by erythromycin, clarithromycin, and roxithromycin, especially at earlier times. β-Lactams were bactericidal against 8 to 10 strains at two times the MIC after 24 h, with slower killing at earlier time periods. Most compounds gave good killing of five M. catarrhalis strains, with β-lactams killing more rapidly than other drugs. ABT-773 and azithromycin gave the longest postantibiotic effects (PAEs) of the ketolide-macrolide-azalide group tested (4.4 to >8.0 h), followed by clarithromycin, erythromycin, and roxithromycin. β-Lactam PAEs were similar and shorter than those of the ketolide-macrolide-azalide group for all strains

Susceptibilities of Haemophilus influenzae and Moraxella catarrhalis to ABT-773 compared to their susceptibilities to 11 other agents.

PubMed

Credito, K L; Lin, G; Pankuch, G A; Bajaksouzian, S; Jacobs, M R; Appelbaum, P C

2001-01-01

The activity of the ketolide ABT-773 against Haemophilus and Moraxella was compared to those of 11 other agents. Against 210 Haemophilus influenzae strains (39.0% beta-lactamase positive), microbroth dilution tests showed that azithromycin and ABT-773 had the lowest MICs (0.5 to 4.0 and 1.0 to 8.0 microg/ml, respectively), followed by clarithromycin and roxithromycin (4.0 to >32.0 microg/ml). Of the beta-lactams, ceftriaxone had the lowest MICs (32.0 microg/ml). Against 50 Moraxella catarrhalis strains, all of the compounds except amoxicillin and cefprozil were active. Time-kill studies against 10 H. influenzae strains showed that ABT-773, at two times the MIC, was bactericidal against 9 of 10 strains, with 99% killing of all strains at the MIC after 24 h; at 12 h, ABT-773 gave 90% killing of all strains at two times the MIC. At 3 and 6 h, killing by ABT-773 was slower, with 99.9% killing of four strains at two times the MIC after 6 h. Similar results were found for azithromycin, with slightly slower killing by erythromycin, clarithromycin, and roxithromycin, especially at earlier times. beta-Lactams were bactericidal against 8 to 10 strains at two times the MIC after 24 h, with slower killing at earlier time periods. Most compounds gave good killing of five M. catarrhalis strains, with beta-lactams killing more rapidly than other drugs. ABT-773 and azithromycin gave the longest postantibiotic effects (PAEs) of the ketolide-macrolide-azalide group tested (4.4 to >8.0 h), followed by clarithromycin, erythromycin, and roxithromycin. beta-Lactam PAEs were similar and shorter than those of the ketolide

Survey of resistance of Pseudomonas aeruginosa from UK patients with cystic fibrosis to six commonly prescribed antimicrobial agents

PubMed Central

Pitt, T; Sparrow, M; Warner, M; Stefanidou, M

2003-01-01

Methods: The susceptibility of 417 CF patient isolates of P aeruginosa from 17 hospitals to six commonly prescribed antibiotics were examined. Isolates were tested by an agar break point dilution method and E-tests according to British Society of Antimicrobial Chemotherapy guidelines. Genotyping of isolates was performed by XbaI DNA macrorestriction and pulsed field gel electrophoresis. Results: 38% of isolates were susceptible to all of the agents tested; almost half were resistant to gentamicin compared with ceftazidime (39%), piperacillin (32%), ciprofloxacin (30%), tobramycin (10%), and colistin (3%). Approximately 40% were resistant to two or more compounds with ceftazidime in combination with gentamicin, piperacillin or ciprofloxacin being the most common cross resistances. Resistance rates were generally similar to those reported recently from the USA and Germany. A selection of resistant isolates proved to be predominantly genotypically distinct by XbaI DNA macrorestriction but six pairs from three centres had similar genotypes. Conclusions: The level of resistance to front line antipseudomonal agents, with the exception of colistin, is disturbingly high. The prudent use of antimicrobial drugs and closer monitoring of accumulation of resistant strain populations should be actively considered. PMID:12947141

Synthesis of tritium-labeled cyadox, a promising antimicrobial growth-promoting agent with high specific activity.

PubMed

Harnud, Sechenchogt; Zhang, Aiqun; Yuan, Zonghui

2018-05-23

Cyadox is a new antimicrobial growth-promoting agent for food-producing animals. Studies on radiolabeled compounds enable the use of sensitive radiometric analytical methods and help in the elucidation of metabolic and elimination pathways. In the present study, 6-[ 3 H]-cyadox with a high specific activity of 2.08 Ci/mmol was prepared by the catalytic bromine-tritium exchange of 4-bromo-2-nitroaniline followed by a three-step microscale synthesis, giving a high yield between 36.16% and 94.75%. Copyright © 2018. Published by Elsevier Ltd.

In vitro activity of five tetracyclines and some other antimicrobial agents against four porcine respiratory tract pathogens.

PubMed

Pijpers, A; Van Klingeren, B; Schoevers, E J; Verheijden, J H; Van Miert, A S

1989-09-01

The minimal inhibitory concentrations (MIC) of five tetracyclines and ten other antimicrobial agents were determined for four porcine bacterial respiratory tract pathogens by the agar dilution method. For the following oxytetracycline-susceptible strains, the MIC50 ranges of the tetracyclines were: P. multocida (n = 17) 0.25-0.5 micrograms/ml; B. bronchiseptica (n = 20) 0.25-1.0 micrograms/ml; H. pleuropneumoniae (n = 20) 0.25-0.5 micrograms/ml; S. suis Type 2 (n = 20) 0.06-0.25 micrograms/ml. For 19 oxytetracycline-resistant P. multocida strains the MIC50 of the tetracyclines varied from 64 micrograms/ml for oxytetracycline to 0.5 micrograms/ml for minocycline. Strikingly, minocycline showed no cross-resistance with oxytetracycline, tetracycline, chlortetracycline and doxycycline in P. multocida and in H. pleuropneumoniae. Moreover, in susceptible strains minocycline showed the highest in vitro activity followed by doxycycline. Low MIC50 values were observed for chloramphenicol, ampicillin, flumequine, ofloxacin and ciprofloxacin against P. multocida and H. pleuropneumoniae. B. bronchiseptica was moderately susceptible or resistant to these compounds. As expected tiamulin, lincomycin, tylosin and spiramycin were not active against H. pleuropneumoniae. Except for flumequine, the MIC50 values of nine antimicrobial agents were low for S. suis Type 2. Six strains of this species showed resistance to the macrolides and lincomycin.

Plasmid-Mediated Antimicrobial Resistance in Staphylococci and Other Firmicutes.

PubMed

Schwarz, Stefan; Shen, Jianzhong; Wendlandt, Sarah; Fessler, Andrea T; Wang, Yang; Kadlec, Kristina; Wu, Cong-Ming

2014-12-01

In staphylococci and other Firmicutes, resistance to numerous classes of antimicrobial agents, which are commonly used in human and veterinary medicine, is mediated by genes that are associated with mobile genetic elements. The gene products of some of these antimicrobial resistance genes confer resistance to only specific members of a certain class of antimicrobial agents, whereas others confer resistance to the entire class or even to members of different classes of antimicrobial agents. The resistance mechanisms specified by the resistance genes fall into any of three major categories: active efflux, enzymatic inactivation, and modification/replacement/protection of the target sites of the antimicrobial agents. Among the mobile genetic elements that carry such resistance genes, plasmids play an important role as carriers of primarily plasmid-borne resistance genes, but also as vectors for nonconjugative and conjugative transposons that harbor resistance genes. Plasmids can be exchanged by horizontal gene transfer between members of the same species but also between bacteria belonging to different species and genera. Plasmids are highly flexible elements, and various mechanisms exist by which plasmids can recombine, form cointegrates, or become integrated in part or in toto into the chromosomal DNA or into other plasmids. As such, plasmids play a key role in the dissemination of antimicrobial resistance genes within the gene pool to which staphylococci and other Firmicutes have access. This chapter is intended to provide an overview of the current knowledge of plasmid-mediated antimicrobial resistance in staphylococci and other Firmicutes.

Phyllanthus wightianus Müll. Arg.: A Potential Source for Natural Antimicrobial Agents

PubMed Central

Natarajan, D.; Srinivasan, R.; Shivakumar, M. S.

2014-01-01

Phyllanthus wightianus belongs to Euphorbiaceae family having ethnobotanical importance. The present study deals with validating the antimicrobial potential of solvent leaf extracts of P. wightianus. 11 human bacterial pathogens (Bacillus subtilis, Streptococcus pneumoniae, Staphylococcus epidermidis, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, Escherichia coli, Shigella flexneri, Proteus vulgaris, and Serratia marcescens) and 4 fungal pathogens (Candida albicans, Cryptococcus neoformans, Mucor racemosus, and Aspergillus niger) were also challenged with solvent leaf extracts usingagar well and disc diffusion methods. Further, identification of the active component present in the bioactive extract was done using GC-MS analysis. Results show that all extracts exhibited broad spectrum (6–29 mm) of antibacterial activity on most of the tested organisms. The results highlight the fact that the well in agar method was more effective than disc diffusion method. Significant antimicrobial activity was detected in methanol extract against S. pneumoniae (29 mm) with MIC and MBC values of 15.62 μg/mL. GC-MS analysis revealed that 29 bioactive constituents were present in methanolic extract of P. wightianus, of which 9,12-octadecaenioic acid (peak area 22.82%; RT-23.97) and N-hexadecanoic acid (peak area 21.55% RT-21.796) are the major compounds. The findings of this study show that P. wightianus extracts may be used as an anti-infective agent in folklore medicine. PMID:24883301

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.

Bacterial meningitis - principles of antimicrobial treatment.

PubMed

Jawień, Miroslaw; Garlicki, Aleksander M

2013-01-01

Bacterial meningitis is associated with significant morbidity and mortality despite the availability of effective antimicrobial therapy. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Successful treatment of bacterial meningitis requires the knowledge on epidemiology including prevalence of antimicrobial resistant pathogens, pathogenesis of meningitis, pharmacokinetics and pharmacodynamics of antimicrobial agents. The emergence of antibiotic-resistant bacterial strains in recent years has necessitated the development of new strategies for empiric antimicrobial therapy for bacterial meningitis.

Colloid particle formulations for antimicrobial applications.

PubMed

Halbus, Ahmed F; Horozov, Tommy S; Paunov, Vesselin N

2017-11-01

Colloidal particles are being extensively studied in various antimicrobial applications due to their small size to volume ratio and ability to exhibit a wide spectrum of antibacterial, antifungal, antialgal and antiviral action. The present review focuses on various nanoparticles (NPs) of inorganic, organic and hybrid materials, and discusses some of the methods for their preparation as well as mechanisms of their antimicrobial action. We consider the antimicrobial applications of metal oxide nanoparticles (ZnO, MgO, CuO, Cu 2 O, Al 2 O 3 , TiO 2 , CeO 2 and Y 2 O 3 ), metal nanoparticles (NPs), such as copper, silver and gold, metal hydroxide NPs such as Mg(OH) 2 as well as hybrid NPs made from biodegradable materials, such as chitosan, lignin and dextran, loaded with other antimicrobial agents. Recent developments for targeted delivery of antimicrobials by using colloid antibodies for microbial cell shape and surface recognition are also discussed. We also consider recent advances in the functionalization of nanoparticles and their potential antimicrobial applications as a viable alternative of conventional antibiotics and antiseptic agents which can help to tackle antimicrobial resistance. The review also covers the recently developed environmentally benign NPs (EbNPs) as a "safer-by-design" green chemistry solution of the post use fate of antimicrobial nanomaterials. Copyright © 2017 Elsevier B.V. All rights reserved.

Novel natural food antimicrobials.

PubMed

Juneja, Vijay K; Dwivedi, Hari P; Yan, Xianghe

2012-01-01

Naturally occurring antimicrobial compounds could be applied as food preservatives to protect food quality and extend the shelf life of foods and beverages. These compounds are naturally produced and isolated from various sources, including plants, animals and microorganisms, in which they constitute part of host defense systems. Many naturally occurring compounds, such as nisin, plant essential oils, and natamycin, have been widely studied and are reported to be effective in their potential role as antimicrobial agents against spoilage and pathogenic microorganisms. Although some of these natural antimicrobials are commercially available and applied in food processing, their efficacy, consumer acceptance and regulation are not well defined. This manuscript reviews natural antimicrobial compounds with reference to their applications in food when applied individually or in combination with other hurdles. It also reviews the mechanism of action of selected natural antimicrobials, factors affecting their antimicrobial activities, and future prospects for use of natural antimicrobials in the food industry.

[Consensus for antimicrobial susceptibility testing for Enterobacteriaceae. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].

PubMed

Famiglietti, A; Quinteros, M; Vázquez, M; Marín, M; Nicola, F; Radice, M; Galas, M; Pasterán, F; Bantar, C; Casellas, J M; Kovensky Pupko, J; Couto, E; Goldberg, M; Lopardo, H; Gutkind, G; Soloaga, R

2005-01-01

Taking into account previous recommendations from the National Committee for Clinical Laboratory Standards (NCCLS), the Antimicrobial Committee, Sociedad Argentina de Bacteriología Clínica (SADEBAC), Asociación Argentina de Microbiología (AAM), and the experience from its members and some invited microbiologists, a consensus was obtained for antimicrobial susceptibility testing and interpretation in most frequent enterobacterial species isolated from clinical samples in our region. This document describes the natural antimicrobial resistance of some Enterobacteriaceae family members, including the resistance profiles due to their own chromosomal encoded beta-lactamases. A list of the antimicrobial agents that should be tested, their position on the agar plates, in order to detect the most frequent antimicrobial resistance mechanisms, and considerations on which antimicrobial agents should be reported regarding to the infection site and patient characteristics are included. Also, a description on appropriate phenotypic screening and confirmatory test for detection of prevalent extended spectrum beta-lactamases in our region are presented. Finally, a summary on frequent antimicrobial susceptibility profiles and their probably associated resistance mechanisms, and some infrequent antimicrobial resistance profiles that deserve confirmation are outlined.

Uses of antimicrobial genes from microbial genome

DOEpatents

Sorek, Rotem; Rubin, Edward M.

2013-08-20

We describe a method for mining microbial genomes to discover antimicrobial genes and proteins having broad spectrum of activity. Also described are antimicrobial genes and their expression products from various microbial genomes that were found using this method. The products of such genes can be used as antimicrobial agents or as tools for molecular biology.

Antimicrobial Stewardship: A Call to Action for Surgeons

PubMed Central

Duane, Therese M.; Catena, Fausto; Tessier, Jeffrey M.; Coccolini, Federico; Kao, Lillian S.; De Simone, Belinda; Labricciosa, Francesco M.; May, Addison K.; Ansaloni, Luca; Mazuski, John E.

2016-01-01

Abstract Despite current antimicrobial stewardship programs (ASPs) being advocated by infectious disease specialists and discussed by national and international policy makers, ASPs coverage remains limited to only certain hospitals as well as specific service lines within hospitals. The ASPs incorporate a variety of strategies to optimize antimicrobial agent use in the hospital, yet the exact set of interventions essential to ASP success remains unknown. Promotion of ASPs across clinical practice is crucial to their success to ensure standardization of antimicrobial agent use within an institution. To effectively accomplish this standardization, providers who actively engage in antimicrobial agent prescribing should participate in the establishment and support of these programs. Hence, surgeons need to play a major role in these collaborations. Surgeons must be aware that judicious antibiotic utilization is an integral part of any stewardship program and necessary to maximize clinical cure and minimize emergence of antimicrobial resistance. The battle against antibiotic resistance should be fought by all healthcare professionals. If surgeons around the world participate in this global fight and demonstrate awareness of the major problem of antimicrobial resistance, they will be pivotal leaders. If surgeons fail to actively engage and use antibiotics judiciously, they will find themselves deprived of the autonomy to treat their patients. PMID:27828764

Antimicrobial Peptides As Biologic and Immunotherapeutic Agents against Cancer: A Comprehensive Overview.

PubMed

Roudi, Raheleh; Syn, Nicholas L; Roudbary, Maryam

2017-01-01

Antimicrobial peptides (AMPs) are a pervasive and evolutionarily ancient component of innate host defense which is present in virtually all classes of life. In recent years, evidence has accumulated that parallel or de novo mechanisms by which AMPs curb infectious pathologies are also effective at restraining cancer cell proliferation and dissemination, and have consequently stimulated significant interest in their deployment as novel biologic and immunotherapeutic agents against human malignancies. In this review, we explicate the biochemical underpinnings of their tumor-selectivity, and discuss results of recent clinical trials (outside of oncologic indications) which substantiate their safety and tolerability profiles. Next, we present evidence for their preclinical antitumor activity, systematically organized by the major and minor classes of natural AMPs. Finally, we discuss the barriers to their clinical implementation and envision directions for further development.

Prudent Use of Antimicrobials in Exotic Animal Medicine.

PubMed

Broens, Els M; van Geijlswijk, Ingeborg M

2018-05-01

Reduction of antimicrobial use can result in reduction of resistance in commensal bacteria. In exotic animals, information on use of antimicrobials and resistance in commensals and pathogens is scarce. However, use of antimicrobials listed as critically important antimicrobials for human medicine seems high in exotic animals. Ideally, the selection of a therapy should be based on an accurate diagnosis and antimicrobial susceptibility testing. When prescribing antimicrobials based on empiricism, knowledge of the most common pathogens causing specific infections and the antimicrobial spectrum of antimicrobial agents is indispensable. Implementing antimicrobial stewardship promotes the prudent use of antimicrobials in exotic animals. Copyright © 2018 Elsevier Inc. All rights reserved.

Antimicrobial resistance incidence and risk factors among Helicobacter pylori-infected persons, United States.

PubMed

Duck, William M; Sobel, Jeremy; Pruckler, Janet M; Song, Qunsheng; Swerdlow, David; Friedman, Cindy; Sulka, Alana; Swaminathan, Balasubra; Taylor, Tom; Hoekstra, Mike; Griffin, Patricia; Smoot, Duane; Peek, Rick; Metz, David C; Bloom, Peter B; Goldschmidt, Steven; Parsonnet, Julie; Triadafilopoulos, George; Perez-Perez, Guillermo I; Vakil, Nimish; Ernst, Peter; Czinn, Steve; Dunne, Donald; Gold, Ben D

2004-06-01

Helicobacter pylori is the primary cause of peptic ulcer disease and an etiologic agent in the development of gastric cancer. H. pylori infection is curable with regimens of multiple antimicrobial agents, and antimicrobial resistance is a leading cause of treatment failure. The Helicobacter pylori Antimicrobial Resistance Monitoring Program (HARP) is a prospective, multicenter U.S. network that tracks national incidence rates of H. pylori antimicrobial resistance. Of 347 clinical H. pylori isolates collected from December 1998 through 2002, 101 (29.1%) were resistant to one antimicrobial agent, and 17 (5%) were resistant to two or more antimicrobial agents. Eighty-seven (25.1%) isolates were resistant to metronidazole, 45 (12.9%) to clarithromycin, and 3 (0.9%) to amoxicillin. On multivariate analysis, black race was the only significant risk factor (p < 0.01, hazard ratio 2.04) for infection with a resistant H. pylori strain. Formulating pretreatment screening strategies or providing alternative therapeutic regimens for high-risk populations may be important for future clinical practice.

Antimicrobial Resistance Incidence and Risk Factors among Helicobacter pylori–Infected Persons, United States

PubMed Central

Sobel, Jeremy; Pruckler, Janet M.; Song, Qunsheng; Swerdlow, David; Friedman, Cindy; Sulka, Alana; Swaminathan, Balasubra; Taylor, Tom; Hoekstra, Mike; Griffin, Patricia; Smoot, Duane; Peek, Rick; Metz, David C.; Bloom, Peter B.; Goldschmid, Steven; Parsonnet, Julie; Triadafilopoulos, George; Perez-Perez, Guillermo I.; Vakil, Nimish; Ernst, Peter; Czinn, Steve; Dunne, Donald; Gold, Ben D.

2004-01-01

Helicobacter pylori is the primary cause of peptic ulcer disease and an etiologic agent in the development of gastric cancer. H. pylori infection is curable with regimens of multiple antimicrobial agents, and antimicrobial resistance is a leading cause of treatment failure. The Helicobacter pylori Antimicrobial Resistance Monitoring Program (HARP) is a prospective, multicenter U.S. network that tracks national incidence rates of H. pylori antimicrobial resistance. Of 347 clinical H. pylori isolates collected from December 1998 through 2002, 101 (29.1%) were resistant to one antimicrobial agent, and 17 (5%) were resistant to two or more antimicrobial agents. Eighty-seven (25.1%) isolates were resistant to metronidazole, 45 (12.9%) to clarithromycin, and 3 (0.9%) to amoxicillin. On multivariate analysis, black race was the only significant risk factor (p < 0.01, hazard ratio 2.04) for infection with a resistant H. pylori strain. Formulating pretreatment screening strategies or providing alternative therapeutic regimens for high-risk populations may be important for future clinical practice. PMID:15207062

Bacteriophages show promise as antimicrobial agents.

PubMed

Alisky, J; Iczkowski, K; Rapoport, A; Troitsky, N

1998-01-01

The emergence of antibiotic-resistant bacteria has prompted interest in alternatives to conventional drugs. One possible option is to use bacteriophages (phage) as antimicrobial agents. We have conducted a literature review of all Medline citations from 1966-1996 that dealt with the therapeutic use of phage. There were 27 papers from Poland, the Soviet Union, Britain and the U.S.A. The Polish and Soviets administered phage orally, topically or systemically to treat a wide variety of antibiotic-resistant pathogens in both adults and children. Infections included suppurative wound infections, gastroenteritis, sepsis, osteomyelitis, dermatitis, empyemas and pneumonia; pathogens included Staphylococcus, Streptococcus, Klebsiella, Escherichia, Proteus, Pseudomonas, Shigella and Salmonella spp. Overall, the Polish and Soviets reported success rates of 80-95% for phage therapy, with rare, reversible gastrointestinal or allergic side effects. However, efficacy of phage was determined almost exclusively by qualitative clinical assessment of patients, and details of dosages and clinical criteria were very sketchy. There were also six British reports describing controlled trials of phage in animal models (mice, guinea pigs and livestock), measuring survival rates and other objective criteria. All of the British studies raised phage against specific pathogens then used to create experimental infections. Demonstrable efficacy against Escherichia, Acinetobacter, Pseudomonas and Staphylococcus spp. was noted in these model systems. Two U.S. papers dealt with improving the bioavailability of phage. Phage is sequestered in the spleen and removed from circulation. This can be overcome by serial passage of phage through mice to isolate mutants that resist sequestration. In conclusion, bacteriophages may show promise for treating antibiotic resistant pathogens. To facilitate further progress, directions for future research are discussed and a directory of authors from the reviewed

Investigation on antimicrobial agents of the terrestrial Streptomyces sp. BCC71188.

PubMed

Supong, Khomsan; Sripreechasak, Paranee; Tanasupawat, Somboon; Danwisetkanjana, Kannawat; Rachtawee, Pranee; Pittayakhajonwut, Pattama

2017-01-01

The terrestrial actinomycete strain BCC71188 was identified as Streptomyces by its morphology (having spiral chain spore on the aerial mycelium), chemotaxonomy (containing LL-diaminopimelic acid in the cell wall), and 16S rRNA gene sequence analysis [showing high similarity values compared with Streptomyces samsunensis M1463 T (99.85 %) and Streptomyces malaysiensis NBRC 16446 T (99.40 %)]. The crude extract exhibited antimalarial against Plasmodium falciparum (IC 50 0.19 μg/ml), anti-TB against Mycobacterial tuberculosis (MIC 6.25 μg/ml), and antibacterial against Bacillus cereus (MIC 1.56 μg/ml) activities. Therefore, chemical investigation was conducted by employing bioassay-guided method and led to the isolation of 19 compounds including two cyclic peptides (1-2), five macrolides (3-7), new naphthoquinone (8), nahuoic acid C (9), geldanamycin derivatives (10-13), cyclooctatin (14), germicidins A (15) and C (16), actinoramide A (17), abierixin, and 29-O-methylabierixin. These isolated compounds were evaluated for antimicrobial activity, such as antimalarial, anti-TB, and antibacterial activities, and for cytotoxicity against both cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells. Compounds 1-7, 10-14 exhibited antimalarial (IC 50 0.22-7.14 μg/ml), and elaiophylin analogs (4-6) displayed anti-TB (MIC 0.78-12.00 μg/ml) and B. cereus (MIC 0.78-3.13 μg/ml) activities. Compounds 1, 2, 14, and abierixin displayed weak cytotoxicity, indicating a potential for antimicrobial agents.

Antimicrobial activity of pomegranate peel extracts as affected by cultivar.

PubMed

Rosas-Burgos, Ema C; Burgos-Hernández, Armando; Noguera-Artiaga, Luis; Kačániová, Miroslava; Hernández-García, Francisca; Cárdenas-López, José L; Carbonell-Barrachina, Ángel A

2017-02-01

Some studies have reported that different parts of the pomegranate fruit, especially the peel, may act as potential antimicrobial agents and thus might be proposed as a safe natural alternative to synthetic antimicrobial agents. The high tannin content, especially punicalagin, found in pomegranate extracts, has been reported as the main compound responsible for such antimicrobial activity. Because the pomegranate peel chemical composition may vary with the type of cultivar (sweet, sour-sweet and sour), pomegranates may also differ with respect to their antimicrobial capacity. The extract from PTO8 pomegranate cultivar peel had the highest antimicrobial activity, as well as the highest punicalagins (α and β) and ellagic acid concentrations. In the results obtained from both antibacterial and antifungal activity studies, the sour-sweet pomegranate cultivar PTO8 showed the best antimicrobial activity, and the highest ellagic acid concentrations. The results of the present study suggest that ellagic acid content has a significant influence on the antimicrobial activity of the pomegranate extracts investigated. The pomegranate peel of the PTO8 cultivar is a good source of antifungal and antibacterial compounds, and may represent an alternative to antimicrobial agents of synthetic origin. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

2-Amino-1,3,4-thiadiazole as a potential scaffold for promising antimicrobial agents.

PubMed

Serban, Georgeta; Stanasel, Oana; Serban, Eugenia; Bota, Sanda

2018-01-01

Pathogenic microorganisms are causative agents for different types of serious and even lethal infectious diseases. Despite advancements in medication, bacterial and fungal infections continue to be a growing problem in health care. As more and more bacteria become resistant to antibiotics used in therapy and an increasing number of invasive fungal species become resistant to current antifungal medications, there is considerable interest in the development of new compounds with antimicrobial activity. The compounds containing a heterocyclic ring play an important role among organic compounds with biological activity used as drugs in human and veterinary medicine or as insecticides and pesticides in agriculture. Thiadiazoles belong to the classes of nitrogen-sulfur heterocycles with extensive application as structural units of biologically active molecules and as useful intermediates in medicinal chemistry. The potency of the thiadiazole nucleus is demonstrated by the drugs currently used. 1,3,4-Thiadiazoles and some of their derivatives are extensively studied because of their broad spectrum of pharmacological activities. The aim of this review was to highlight the main antimicrobial properties exhibited by derivatives possessing 2-amino-1,3,4-thiadiazole moiety. Many of the reported 2-amino-1,3,4-thiadiazole derivatives can be considered as lead compounds for drug synthesis, and several of them have demonstrated higher antimicrobial activity in comparison to standard drugs. Furthermore, taking into account the reactivity of the amine group in the derivatization process, 2-amino-1,3,4-thiadiazole moiety may be a good scaffold for future pharmacologically active 1,3,4-thiadiazole derivatives.

Soft antimicrobial agents: synthesis and activity of labile environmentally friendly long chain quaternary ammonium compounds.

PubMed

Thorsteinsson, Thorsteinn; Másson, Már; Kristinsson, Karl G; Hjálmarsdóttir, Martha A; Hilmarsson, Hilmar; Loftsson, Thorsteinn

2003-09-11

A series of soft quaternary ammonium antimicrobial agents, which are analogues to currently used quaternary ammonium preservatives such as cetyl pyridinium chloride and benzalkonium chloride, were synthesized. These soft analogues consist of long alkyl chain connected to a polar headgroup via chemically labile spacer group. They are characterized by facile nonenzymatic and enzymatic degradation to form their original nontoxic building blocks. However, their chemical stability has to be adequate in order for them to have antimicrobial effects. Stability studies and antibacterial and antiviral activity measurements revealed relationship between activity, lipophilicity, and stability. Their minimum inhibitory concentration (MIC) was as low as 1 microg/mL, and their viral reduction was in some cases greater than 6.7 log. The structure-activity studies demonstrate that the bioactive compounds (i.e., MIC for Gram-positive bacteria of <10 microg/mL) have an alkyl chain length between 12 and 18 carbon atoms, with a polar headgroup preferably of a small quaternary ammonium group, and their acquired inactivation half-life must be greater than 3 h at 60 degrees C.

Effect of ionizing energy on extracts of Quillaja saponaria to be used as an antimicrobial agent on irradiated edible coating for fresh strawberries

NASA Astrophysics Data System (ADS)

Zúñiga, G. E.; Junqueira-Gonçalves, M. P.; Pizarro, M.; Contreras, R.; Tapia, A.; Silva, S.

2012-01-01

Incorporating antimicrobial compounds into edible films or coatings provides a novel way to improve the safety and shelf life of ready-to-eat foods. Diverse studies with Quillaja saponaria Mol. (popularly named quillay) extracts have demonstrated their potential as antifungal agents against phytopathogenic fungi. Crosslinking induced by ionizing radiation is an effective method for the improvement of both barrier and mechanical properties of the edible films and coatings based on milk proteins. However there are few reports about the effects of γ-radiation on plant extracts. The aim of this work was to evaluate the effect of ionizing radiation (0, 5, 10, 15, 20, 25 and 35 kGy) on extracts prepared from in vitro plants of Q. saponaria to be used as antimicrobial agent in irradiated edible coating based on calcium caseinate and whey protein isolated, and also to establish the concentration of Q. saponaria extract to be added as an antifungal agent in the coating. Gamma irradiation since 15 kGy affects negatively the antimicrobial activity and metabolites composition of extract of Q. saponaria by reducing compounds of phenolic nature. Otherwise no effect on saponins profile was observed even at higher doses. It was possible to conclude that the antifungal activity of Q. saponaria extract is mainly related to phenolic compounds content. In addition, our work also shows that to obtain an efficient antifungal protection is necessary to add a minimum concentration of 6% of the extract after the coating irradiation.

In vitro susceptibility of contagious ovine digital dermatitis associated Treponema spp. isolates to antimicrobial agents in the UK.

PubMed

Angell, Joseph W; Clegg, Simon R; Sullivan, Leigh E; Duncan, Jennifer S; Grove-White, Dai H; Carter, Stuart D; Evans, Nicholas J

2015-12-01

Contagious ovine digital dermatitis (CODD) is an important cause of infectious lameness in sheep in the UK and Ireland and has a severe impact on the welfare of affected individuals. The three treponemal phylogroups Treponema medium/Treponema vincentii-like, Treponema phagedenis-like and Treponema pedis spirochaetes have been associated with clinical CODD lesions and are considered to be a necessary cause of disease. There are scant data on the antimicrobial susceptibility of the treponemes cultured from CODD lesions. The aim of this study was to determine in vitro the miniumum inhibitory concentration/ minimum bactericidal concentration (MIC/MBC) of antimicrobials used in the sheep industry for isolates of the three CODD associated treponeme phylogroups T. medium/T. vincentii-like, T. phagedenis-like and T. pedis. Twenty treponeme isolates; from 19 sheep with clinical CODD lesions. A microdilution method was used to determine in vitro the MIC/MBC of 10 antimicrobial agents for 20 treponeme isolates (five T. medium/T. vincentii-like, 10 T. phagedenis-like and five T. pedis). The antimicrobials tested were penicillin G, amoxicillin, oxytetracycline, tilmicosin, lincomycin, spectinomycin, tylosin, tildipirosin, tulathromycin and gamithromycin. The treponeme isolates tested showed low MICs and MBCs to all 10 antimicrobials tested. They were most susceptible to gamithromycin and tildipirosin (MIC90: 0.0469 mg/L), and were least susceptible to lincomycin, spectinomycin and oxytetracycline (MIC90: 48 mg/L, 24 mg/L and 3 mg/L, respectively). These data are comparable to in vitro antimicrobial susceptibility data for treponemes cultured from bovine digital dermatitis lesions. Dependent on local licensing, penicillin and tilmicosin appear to be the best candidates for future in vivo studies. © 2015 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the ESVD and ACVD.

Antimicrobial Polymers with Metal Nanoparticles

PubMed Central

Palza, Humberto

2015-01-01

Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms. PMID:25607734

Antimicrobial food packaging: potential and pitfalls

PubMed Central

Malhotra, Bhanu; Keshwani, Anu; Kharkwal, Harsha

2015-01-01

Nowadays food preservation, quality maintenance, and safety are major growing concerns of the food industry. It is evident that over time consumers’ demand for natural and safe food products with stringent regulations to prevent food-borne infectious diseases. Antimicrobial packaging which is thought to be a subset of active packaging and controlled release packaging is one such promising technology which effectively impregnates the antimicrobial into the food packaging film material and subsequently delivers it over the stipulated period of time to kill the pathogenic microorganisms affecting food products thereby increasing the shelf life to severe folds. This paper presents a picture of the recent research on antimicrobial agents that are aimed at enhancing and improving food quality and safety by reduction of pathogen growth and extension of shelf life, in a form of a comprehensive review. Examination of the available antimicrobial packaging technologies is also presented along with their significant impact on food safety. This article entails various antimicrobial agents for commercial applications, as well as the difference between the use of antimicrobials under laboratory scale and real time applications. Development of resistance amongst microorganisms is considered as a future implication of antimicrobials with an aim to come up with actual efficacies in extension of shelf life as well as reduction in bacterial growth through the upcoming and promising use of antimicrobials in food packaging for the forthcoming research down the line. PMID:26136740

The diversity of antimicrobial resistance genes among staphylococci of animal origin.

PubMed

Wendlandt, Sarah; Feßler, Andrea T; Monecke, Stefan; Ehricht, Ralf; Schwarz, Stefan; Kadlec, Kristina

2013-08-01

Staphylococci of animal origin harbor a wide variety of resistance genes. So far, more than 40 different resistance genes have been identified in staphylococci from animals. This includes genes that confer resistance to virtually all classes of antimicrobial agents approved for use in animals, such as penicillins, cephalosporins, tetracyclines, macrolides, lincosamides, phenicols, aminoglycosides, aminocyclitols, pleuromutilins, and diaminopyrimidines. The gene products of some of these resistance genes confer resistance to only specific members of a class of antimicrobial agents, whereas others confer resistance to the entire class or even to members of different classes of antimicrobial agents. The resistance mechanisms specified by the resistance genes fall into three major categories: (i) enzymatic inactivation, (ii) active efflux, or (iii) protection/modification/replacement of the cellular target sites of the antimicrobial agents. Mobile genetic elements, in particular plasmids and transposons, play a major role as carriers of antimicrobial resistance genes in animal staphylococci. They facilitate the exchange of resistance genes with staphylococci of human origin but also with other Gram-positive bacteria. Copyright © 2013 Elsevier GmbH. All rights reserved.

[Etiology of urinary tract infections and antimicrobial susceptibility of urinary pathogens].

PubMed

Correia, Carlos; Costa, Elísio; Peres, António; Alves, Madalena; Pombo, Graça; Estevinho, Letícia

2007-01-01

With the objective of knowing the common etiological agents in urinary infection and comparing its antimicrobial susceptibility in nosocomial and community-acquired urinary infections, we analyse all the urine bacteriological exams from the Serviço de Patologia Clínica do Centro Hospitalar do Nordeste, EPE - Unidade Hospitalar de Bragança, during a two years period (April 2004 to March 2006). During this period, 4018 urine bacteriological exams were made. The cultural exam was positive in 572 samples (144 from nosocomial infections and 428 from community-acquired urinary infections). The Escherichia coli was the more isolated strain (68,4 %), followed by Klebsiella spp (7,9%), Pseudomonas aeruginosa (6,1%) and Proteus mirabilis (5,2%). Concerning to antimicrobial susceptibility, Escherichia coli and Klebsiella spp showed a high resistance to the antimicrobials Amoxicillin, Piperacillin, Cephalothin, Ceftazidim and Quinolones. For Enterobacteriaceae Imipenem, Amikacin and Netilmicin were the antimicrobials with more level of susceptibility. Imipenem and Amikacin were the more efficient antimicrobials against Pseudomonas aeruginosa. Concerning to the susceptibility for the same etiological agent, in nosocomial and community-acquired urinary infections, we founded statistical significant differences in the antimicrobials Ticarcillin-clavulanic acid and Collistin for Pseudomonas aeruginosa and in the group of antimicrobials from Quinolones for the Proteus mirabilis. In the other identified agents there were no statistical significant differences for antimicrobials. This study it allows making use of data necessary for the knowledge of etiologic urinary infection agents in Bragança and provides the information about the antimicrobials resistance, which were necessary to initiate an adequate empirical treatment and to elaborate treatment guides.

Effect of mixed antimicrobial agents and flavors in active packaging films.

PubMed

Gutiérrez, Laura; Escudero, Ana; Batlle, Ramón; Nerín, Cristina

2009-09-23

Active packaging is an emerging food technology to improve the quality and safety of food products. Many works have been developed to study the antimicrobial activity of essential oils. Essential oils have been traditionally used as flavorings in food, so they have an important odor impact but they have as well antimicrobial properties that could be used to protect the food. Recent developments in antimicrobial active packaging showed the efficiency of essential oils versus bread and bakery products among other applications. However, one of the main problems to face is the odor and taste they could provide to the packaged food. Using some aromas to mask the odor could be a good approach. That is why the main objective of this paper is to develop an antimicrobial packaging material based on the combination of the most active compounds of essential oils (hydrocinnamaldehyde, oregano essential oil, cinnamaldehyde, thymol, and carvacrol) together with some aromas commonly used in the food industry. A study of the concentration required to get the antimicrobial properties, the organoleptic compatibility with typical aroma present in many food systems (vanilla, banana, and strawberry), and the right combination of both systems has been carried out. Antimicrobial tests of both the mentioned aromas, the main components of some essential oils, and the combination of both groups were carried out against bacteria (Enterococcus faecalis, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Salmonella choleraesuis, Yersinia enterocolitica, Escherichia coli), yeasts (Candida albicans, Debaryomyces hansenii, Zygosaccharomyces rouxii), and molds (Botrytis cinerae, Aspergillus flavus, Penicillium roqueforti, Eurotium repens, Penicillium islandicum, Penicillium commune, Penicillium nalgiovensis). The sensory properties of the combinations were evaluated with a triangular test and classification was by an order test; the odor threshold of the aroma compounds was also

Chimeric peptides as implant functionalization agents for titanium alloy implants with antimicrobial properties.

PubMed

Yucesoy, Deniz T; Hnilova, Marketa; Boone, Kyle; Arnold, Paul M; Snead, Malcolm L; Tamerler, Candan

2015-04-01

Implant-associated infections can have severe effects on the longevity of implant devices and they also represent a major cause of implant failures. Treating these infections associated with implants by antibiotics is not always an effective strategy due to poor penetration rates of antibiotics into biofilms. Additionally, emerging antibiotic resistance poses serious concerns. There is an urge to develop effective antibacterial surfaces that prevent bacterial adhesion and proliferation. A novel class of bacterial therapeutic agents, known as antimicrobial peptides (AMP's), are receiving increasing attention as an unconventional option to treat septic infection, partly due to their capacity to stimulate innate immune responses and for the difficulty of microorganisms to develop resistance towards them. While host- and bacterial- cells compete in determining the ultimate fate of the implant, functionalization of implant surfaces with antimicrobial peptides can shift the balance and prevent implant infections. In the present study, we developed a novel chimeric peptide to functionalize the implant material surface. The chimeric peptide simultaneously presents two functionalities, with one domain binding to a titanium alloy implant surface through a titanium-binding domain while the other domain displays an antimicrobial property. This approach gains strength through control over the bio-material interfaces, a property built upon molecular recognition and self-assembly through a titanium alloy binding domain in the chimeric peptide. The efficiency of chimeric peptide both in-solution and absorbed onto titanium alloy surface was evaluated in vitro against three common human host infectious bacteria, S. mutans, S. epidermidis , and E. coli . In biological interactions such as occurs on implants, it is the surface and the interface that dictate the ultimate outcome. Controlling the implant surface by creating an interface composed chimeric peptides may therefore open up

Alternatives to antibiotics: bacteriocins, antimicrobial peptides and bacteriophages.

PubMed

Joerger, R D

2003-04-01

Bacteriocins, antimicrobial peptides, and bacteriophage have attracted attention as potential substitutes for, or as additions to, currently used antimicrobial compounds. This publication will review research on the potential application of these alternative antimicrobial agents to poultry production and processing. Bacteriocins are proteinaceous compounds of bacterial origin that are lethal to bacteria other than the producing strain. It is assumed that some of the bacteria in the intestinal tract produce bacteriocins as a means to achieve a competitive advantage, and bacteriocin-producing bacteria might be a desirable part of competitive exclusion preparations. Purified or partially purified bacteriocins could be used as preservatives or for the reduction or elimination of certain pathogens. Currently only nisin, produced by certain strains of Lactococcus lactis subsp. lactis, has regulatory approval for use in certain foods, and its use for poultry products has been studied extensively. Exploration of the application of antimicrobial peptides from sources other than bacteria to poultry has not yet commenced to a significant extent. Evidence for the ability of chickens to produce such antimicrobial peptides has been provided, and it is likely that these peptides play an important role in the defense against various pathogens. Bacteriophages have received renewed attention as possible agents against infecting bacteria. Evidence from several trials indicates that phage therapy can be effective under certain circumstances. Numerous obstacles for the use of phage as antimicrobials for poultry or poultry products remain. Chiefly among them are the narrow host range of many phages, the issue of phage resistance, and the possibility of phage-mediated transfer of genetic material to bacterial hosts. Regulatory issues and the high cost of producing such alternative antimicrobial agents are also factors that might prevent application of these agents in the near future.

Antimicrobial Prophylaxis in Adults

PubMed Central

Enzler, Mark J.; Berbari, Elie; Osmon, Douglas R.

2011-01-01

Antimicrobial prophylaxis is commonly used by clinicians for the prevention of numerous infectious diseases, including herpes simplex infection, rheumatic fever, recurrent cellulitis, meningococcal disease, recurrent uncomplicated urinary tract infections in women, spontaneous bacterial peritonitis in patients with cirrhosis, influenza, infective endocarditis, pertussis, and acute necrotizing pancreatitis, as well as infections associated with open fractures, recent prosthetic joint placement, and bite wounds. Perioperative antimicrobial prophylaxis is recommended for various surgical procedures to prevent surgical site infections. Optimal antimicrobial agents for prophylaxis should be bactericidal, nontoxic, inexpensive, and active against the typical pathogens that can cause surgical site infection postoperatively. To maximize its effectiveness, intravenous perioperative prophylaxis should be administered within 30 to 60 minutes before the surgical incision. Antimicrobial prophylaxis should be of short duration to decrease toxicity and antimicrobial resistance and to reduce cost. PMID:21719623

Antimicrobial Agents Used in the Treatment of Peri-Implantitis Alter the Physicochemistry and Cytocompatibility of Titanium Surfaces.

PubMed

Kotsakis, Georgios A; Lan, Caixia; Barbosa, Joao; Lill, Krista; Chen, Ruoqiong; Rudney, Joel; Aparicio, Conrado

2016-07-01

Chemotherapeutic agents (ChAs) are considered an integral part of current treatment protocols for the decontamination of titanium implants with peri-implantitis, based on their antimicrobial effect. Despite the proven antimicrobial effect of ChAs on titanium-bound biofilms, previous studies have elucidated an unexpected disassociation between bacterial reduction and biologically acceptable treatment outcomes. In this study, the authors hypothesize that ChAs residues alter titanium physicochemistry and thus compromise cellular response to decontaminated surfaces. Grit-blasted acid-etched titanium disks were contaminated with multispecies microcosm biofilms grown from in vivo peri-implant plaque samples. To simulate implant decontamination, the contaminated disks were burnished with 0.12% chlorhexidine, 20% citric acid, 24% EDTA/1.5% NaOCl, or sterile saline and assessed surface physicochemical properties. Sterile untreated surfaces were the controls. The biologic effects of decontamination were assessed via cell proliferation and differentiation assays. Bacterial counts after decontamination confirmed that the ChAs were antimicrobial. X-ray photoelectron spectroscopy invariably detected elemental contaminants associated with each ChA molecule or salt that significantly altered wettability compared with controls. Notably, all surfaces with ChA residues showed some cytotoxic effect compared with controls (P <0.05). Increased cell counts were consistently found in the saline-treated group compared with chlorhexidine (P = 0.03). Interestingly, no association was found between antimicrobial effect and cell counts (P >0.05). ChA-specific residues left on the titanium surfaces altered titanium physical properties and adversely affected the osteoblastic response irrespective of their observed antimicrobial effect. Chlorhexidine may compromise the biocompatibility of titanium surfaces, and its use is not recommended to detoxify implants. Sterile saline, citric acid, and Na

Archetypal tryptophan-rich antimicrobial peptides: properties and applications.

PubMed

Shagaghi, Nadin; Palombo, Enzo A; Clayton, Andrew H A; Bhave, Mrinal

2016-02-01

Drug-resistant microorganisms ('superbugs') present a serious challenge to the success of antimicrobial treatments. Subsequently, there is a crucial need for novel bio-control agents. Many antimicrobial peptides (AMPs) show a broad-spectrum activity against bacteria, fungi or viruses and are strong candidates to complement or substitute current antimicrobial agents. Some AMPs are also effective against protozoa or cancer cells. The tryptophan (Trp)-rich peptides (TRPs) are a subset of AMPs that display potent antimicrobial activity, credited to the unique biochemical properties of tryptophan that allow it to insert into biological membranes. Further, many Trp-rich AMPs cross bacterial membranes without compromising their integrity and act intracellularly, suggesting interactions with nucleic acids and enzymes. In this work, we overview some archetypal TRPs derived from natural sources, i.e., indolicidin, tritrpticin and lactoferricin, summarising their biochemical properties, structures, antimicrobial activities, mechanistic studies and potential applications.

Effect of the addition of antimicrobial agents on Shore A hardness and roughness of soft lining materials.

PubMed

Urban, Vanessa M; Lima, Thiago F; Bueno, Mirian G; Giannini, Marcelo; Arioli Filho, João N; de Almeida, Ana Lúcia P F; Neppelenbroek, Karin H

2015-04-01

While the incorporation of antimicrobial agents into soft denture liners has been suggested as a reliable alternative treatment for denture stomatitis, it may affect the liner's properties. The effect of addition of antimicrobial agents for the treatment of denture stomatitis on the surface roughness and Shore A hardness of soft lining materials was evaluated. The test groups comprised specimens (36 × 7 × 6 mm(3) ) of soft materials (Softone and Trusoft) without (control) or with incorporation of drugs (nystatin, miconazole, ketoconazole, chlorhexidine diacetate, and itraconazole). Hardness (Shore A) and roughness (Ra) were evaluated after immersion of specimens (n = 10) in distilled water at 37°C for 24 hours, 7 and 14 days. Data were analyzed by 3-way ANOVA/Tukey's test (α = 0.05). After 14 days, an increase (p < 0.05) was observed in the hardness of soft materials with time for the modified specimens, except for itraconazole. Addition of drugs increased the Softone roughness only for the addition of miconazole and chlorhexidine (p < 0.05), and did not increase the roughness of Trusoft with time. Only chlorhexidine and itraconazole altered the roughness compared to the control for each material (p < 0.05). The smallest changes of hardness and roughness with time in the modified groups compared to controls were observed for itraconazole groups for both materials. © 2014 by the American College of Prosthodontists.

Novel aminopyrimidinyl benzimidazoles as potentially antimicrobial agents: Design, synthesis and biological evaluation.

PubMed

Liu, Han-Bo; Gao, Wei-Wei; Tangadanchu, Vijai Kumar Reddy; Zhou, Cheng-He; Geng, Rong-Xia

2018-01-01

A series of novel aminopyrimidinyl benzimidazoles as potentially antimicrobial agents were designed, synthesized and characterized by IR, NMR and HRMS spectra. The biological evaluation in vitro revealed that some of the target compounds exerted good antibacterial and antifungal activity in comparison with the reference drugs. Noticeably, compound 7d could effectively inhibit the growth of A. flavus, E. coli DH52 and MRSA with MIC values of 1, 1 and 8 μg/mL, respectively. Further studies revealed that pyrimidine derivative 7d could exhibit bactericidal mode of action against both Gram positive (S. aureus and MRSA) and Gram negative (P. aeruginosa) bacteria. The active molecule 7d showed low cell toxicity and did not obviously trigger the development of resistance in bacteria even after 16 passages. Furthermore, compound 7d was able to beneficially regulate reactive oxygen species (ROS) generation for an excellent safety profile. Molecular docking study revealed that compound 7d could bind with DNA gyrase by the formation of hydrogen bonds. The preliminary exploration for antimicrobial mechanism disclosed that compound 7d could effectively intercalate into calf thymus DNA to form a steady supramolecular complex, which might further block DNA replication to exert the powerful bioactivities. The binding investigation of compound 7d with human serum albumins (HSA) revealed that this molecule could be effectively transported by HSA. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Adaptive Resistance to Biocides in Salmonella enterica and Escherichia coli O157 and Cross-Resistance to Antimicrobial Agents

PubMed Central

Braoudaki, M.; Hilton, A. C.

2004-01-01

The mechanisms by which bacteria resist killing by antibiotics and biocides are still poorly defined, although repeated exposure to sublethal concentrations of antibacterial agents undoubtedly contributes to their development. This study aimed both to investigate the potential of Salmonella enterica and Escherichia coli O157 for adaptive resistance to commonly used biocides and to determine any cross-resistance to antibiotics. Strains were repeatedly passaged in media containing increasing concentrations of a biocide or antibiotic until adaptive resistance was obtained. A wide panel of antimicrobial agents was then screened by using the adapted strain to determine cross-resistance, if any. Adaptive resistance was readily achieved for both S. enterica and E. coli O157. Cross-resistance in adaptively resistant S. enterica varied with the serotype; Salmonella enterica serovar Enteritidis expressed cross-resistance to chloramphenicol, whereas Salmonella enterica serovar Typhimurium expressed cross-resistance to chlorhexidine. Benzalkonium chloride-resistant Salmonella enterica serovar Virchow showed elevated resistance to chlorhexidine; however, chlorhexidine-resistant Salmonella serovar Virchow did not demonstrate reciprocal cross-resistance to benzalkonium chloride, suggesting specific rather than generic resistance mechanisms. E. coli O157 strains acquired high levels of resistance to triclosan after only two sublethal exposures and, when adapted, repeatedly demonstrated decreased susceptibilities to various antimicrobial agents, including chloramphenicol, erythromycin, imipenem, tetracycline, and trimethoprim, as well as to a number of biocides. These observations raise concern over the indiscriminate and often inappropriate use of biocides, especially triclosan, in situations where they are unnecessary, whereby they may contribute to the development of microbial resistance mechanisms. PMID:14715734

Impact of Feed Supplementation with Antimicrobial Agents on Growth Performance of Broiler Chickens, Clostridium perfringens and Enterococcus Counts, and Antibiotic Resistance Phenotypes and Distribution of Antimicrobial Resistance Determinants in Escherichia coli Isolates▿

PubMed Central

Diarra, Moussa S.; Silversides, Fred G.; Diarrassouba, Fatoumata; Pritchard, Jane; Masson, Luke; Brousseau, Roland; Bonnet, Claudie; Delaquis, Pascal; Bach, Susan; Skura, Brent J.; Topp, Edward

2007-01-01

The effects of feed supplementation with the approved antimicrobial agents bambermycin, penicillin, salinomycin, and bacitracin or a combination of salinomycin plus bacitracin were evaluated for the incidence and distribution of antibiotic resistance in 197 commensal Escherichia coli isolates from broiler chickens over 35 days. All isolates showed some degree of multiple antibiotic resistance. Resistance to tetracycline (68.5%), amoxicillin (61.4%), ceftiofur (51.3%), spectinomycin (47.2%), and sulfonamides (42%) was most frequent. The levels of resistance to streptomycin, chloramphenicol, and gentamicin were 33.5, 35.5, and 25.3%, respectively. The overall resistance levels decreased from day 7 to day 35 (P < 0.001). Comparing treatments, the levels of resistance to ceftiofur, spectinomycin, and gentamicin (except for resistance to bacitracin treatment) were significantly higher in isolates from chickens receiving feed supplemented with salinomycin than from the other feeds (P < 0.001). Using a DNA microarray analysis capable of detecting commonly found antimicrobial resistance genes, we characterized 104 tetracycline-resistant E. coli isolates from 7- to 28-day-old chickens fed different growth promoters. Results showed a decrease in the incidence of isolates harboring tet(B), blaTEM, sulI, and aadA and class 1 integron from days 7 to 35 (P < 0.01). Of the 84 tetracycline-ceftiofur-resistant E. coli isolates, 76 (90.5%) were positive for blaCMY-2. The proportions of isolates positive for sulI, aadA, and integron class 1 were significantly higher in salinomycin-treated chickens than in the control or other treatment groups (P < 0.05). These data demonstrate that multiantibiotic-resistant E. coli isolates can be found in broiler chickens regardless of the antimicrobial growth promoters used. However, the phenotype and the distribution of resistance determinants in E. coli can be modulated by feed supplementation with some of the antimicrobial agents used in broiler

Natural antimicrobial/antioxidant agents in meat and poultry products as well as fruits and vegetables: A review.

PubMed

Aziz, Marya; Karboune, Salwa

2018-02-11

Synthetic preservatives are widely used by the food industry to control the growth of spoilage and pathogenic microorganisms and to inhibit the process of lipid oxidation extending the shelf-life, quality and safety of food products. However, consumer's preference for natural food additives and concern regarding the safety of synthetic preservatives prompted the food industry to look for natural alternatives. Natural antimicrobials, including plant extracts and their essential oils, enzymes, peptides, bacteriocins, bacteriophages, and fermented ingredients have all been shown to have the potential for use as alternatives to chemical antimicrobials. Some spices, herbs and other plant extracts were also reported to be strong antioxidants. The antimicrobial/antioxidant activities of some plant extracts and/or their essential oils are mainly due to the presence of some major bioactive compounds, including phenolic acids, terpenes, aldehydes, and flavonoids. The proposed mechanisms of action of these natural preservatives are reported. An overview of the research done on the direct incorporation of natural preservatives agents into meat and poultry products as well as fruit and vegetables to extend their shelf-life is presented. The development of edible packaging materials containing natural preservatives is growing and their applications in selected food products are also presented in this review.

Antimicrobial susceptibility of Brachyspira hyodysenteriae in Switzerland.

PubMed

Kirchgässner, C; Schmitt, S; Borgström, A; Wittenbrink, M M

2016-06-01

Brachyspira (B.) hyodysenteriae is the causative agent of swine dysentery (SD), a severe mucohaemorrhagic diarrheal disease in pigs worldwide. So far, the antimicrobial susceptibility patterns of B. hyodysenteriae in Switzerland have not been investigated. Therefore, a panel of 30 porcine B. hyodysenteriae isolates were tested against 6 antimicrobial agents by using the VetMIC Brachy panel, a broth microdilution test. Tiamulin and valnemulin showed high antimicrobial activity inhibiting all isolates at low concentrations. The susceptibility testing of doxycycline revealed values from ≤0.25 μg/ ml (47%) to 2 μg/ml (10%). The MIC values of lincomycin ranged between ≤0.5 μg/ml (30%) and 32 μg/ml (43%). For tylosin, 57% of the isolates could not be inhibited at the highest concentration of ≥128 μg/ml. The MIC values for tylvalosin were between ≤0.25 μg/ml (10%) and 8 μg/ml (20%). These findings reveal Switzerland's favourable situation compared to other European countries. Above all, tiamulin and valnemulin are still effective antimicrobial agents and can be further used for the treatment of SD.

Antimicrobials and therapeutic decision making: an historical perspective.

PubMed

Quintiliani, R; Nightingale, C H

1991-01-01

In an effort to remedy inappropriate and excessive use of antimicrobials and to control costs, most hospitals have developed some type of antimicrobial management program. At Hartford Hospital, our most effective approaches have been those that reduce the chances for physician error, decrease the burden on ancillary services, and encourage short hospital stays. These include automatic correction of dose and dosing intervals of antimicrobials and, if possible, their conversion by pharmacy to cost-effective alternative agents; daily review of patients who are taking the drugs by an antimicrobial team; and replacement of parenteral with oral agents as soon as possible. Physician acceptance of these approaches will require significant changes in traditional prescribing styles and willingness to allow pharmacists to implement the recommendations of therapeutic and medical staff committees.

National Antimicrobial Resistance Monitoring System (NARMS) Program

USDA-ARS?s Scientific Manuscript database

The National Antimicrobial Resistance Monitoring System (NARMS) – Enteric Bacteria is a national public health surveillance system in the United States that tracks changes in the susceptibility of certain enteric bacteria to antimicrobial agents of human and veterinary medical importance. The NARMS ...

Advances in pharmacovigilance initiatives surrounding antimicrobial resistance-Indian perspective.

PubMed

Bairy, Laxminarayana Kurady; Nayak, Veena; A, Avinash; Kunder, Sushil Kiran

2016-08-01

In recent years the development of antimicrobial resistance has been accelerating, the discovery of new antimicrobial agents has slowed substantially in past decades. This review mainly focuses on the problem of antimicrobial resistance(AMR); the various contributor mechanisms, consequences and future of AMR. The review also highlights the irrational use of antimicrobials, improving their usage and problems associated with pharmacovigilance of antimicrobial resistance. Pharmacovigilance in the form of surveillance of antibiotic use is being done in 90% of the countries worldwide through the WHONET program developed by WHO. However, the data comes from a limited area of the globe. Data from every part of the world is required, so that there is geographical representation of every region. A major hurdle in quantifying the extent of antimicrobial resistance is the fact that there are several known microbes, that may turn out to be resistant to one or more of the several known antimicrobial agents. The global action plan initiated by WHO, if implemented successfully will definitely reduce AMR and will help in evaluating treatment interventions.

Comparative in vitro susceptibilities and bactericidal activities of investigational fluoroquinolone ABT-492 and other antimicrobial agents against human mycoplasmas and ureaplasmas.

PubMed

Waites, Ken B; Crabb, Donna M; Duffy, Lynn B

2003-12-01

We determined in vitro susceptibilities for ABT-492 and other antimicrobials against Mycoplasma pneumoniae, Mycoplasma fermentans, Mycoplasma hominis, and Ureaplasma species. ABT-492 MICs were < or =1 microg/ml, and the agent was bactericidal against selected isolates of M. pneumoniae and M. hominis. ABT-492 has potential for treatment of infections due to these microorganisms.

Synthesis, spectroscopic characterization and computational chemical study of 5-cyano-2-thiouracil derivatives as potential antimicrobial agents

NASA Astrophysics Data System (ADS)

Rizk, Sameh A.; El-Naggar, Abeer M.; El-Badawy, Azza A.

2018-03-01

A series of 5-cyano-2-thiouracil derivatives, containing diverse hydrophobic groups in the 2-, 4- and 6-positions, were synthesized through one pot reaction of thiophene 2-carboxaldehyde, ethylcyanoacetate and thiourea using classic reflux-based method as well as microwave-assisted methods. Such prepared compounds were reacted with different electrophilic reagents to synthesize potent anti-microbial agents, e.g. 1,3,4-thiadiazinopyrimidine, hydrazide and triazolopyrimidine derivatives (compounds 4a-e, 9 and 10-12) respectively. The density functional theory (DFT) was then applied to explore the structural and electronic characteristics of these materials. It is found that compound 12 exhibited the highest antibacterial and antifungal activity against C. Albicans showing six-fold increasing biological affinity compared to that of Colitrimazole drug with MIC values 7.8 and 49 μg/mL, respectively. All the synthesized compounds have been characterized based on their elemental analyses and spectral data. Such compounds can be submitted to in vivo antimicrobial studies in future works.

Design and synthesis of some new 2,3'-bipyridine-5-carbonitriles as potential anti-inflammatory/antimicrobial agents.

PubMed

Elzahhar, Perihan A; Elkazaz, Salwa; Soliman, Raafat; El-Tombary, Alaa A; Shaltout, Hossam A; El-Ashmawy, Ibrahim M; Abdel Wahab, Abeer E; El-Hawash, Soad A

2017-08-01

Inflammation may cause accumulation of fluid in the injured area, which may promote bacterial growth. Other reports disclosed that non-steroidal anti-inflammatory drugs may enhance progression of bacterial infection. This work describes synthesis of new series of 2,3'-bipyridine-5-carbonitriles as structural analogs of etoricoxib, linked at position-6 to variously substituted thio or oxo moieties. Biological screening results revealed that compounds 2b, 4b, 7e and 8 showed significant acute and chronic AI activities and broad spectrum of antimicrobial activity. In addition, similarity ensemble approach was applied to predict potential biological targets of the tested compounds. Then, pharmacophore modeling study was employed to determine the most important structural parameters controlling bioactivity. Moreover, title compounds showed physicochemical properties within those considered adequate for drug candidates. This study explored the potential of such series of compounds as structural leads for further modification to develop a new class of dual AI-antimicrobial agents.

Antimicrobial susceptibility of starter culture bacteria used in Norwegian dairy products.

PubMed

Katla, A K; Kruse, H; Johnsen, G; Herikstad, H

2001-07-20

Commercial starter culture bacteria are widely used in the production of dairy products and could represent a potential source for spread of genes encoding resistance to antimicrobial agents. To learn more about the antimicrobial susceptibility of starter culture bacteria used in Norwegian dairy products, a total of 189 isolates of lactic acid bacteria were examined for susceptibility to ampicillin, penicillin G, cephalothin, vancomycin, bacitracin, gentamicin, streptomycin, erythromycin, tetracycline, chloramphenicol, quinupristin/dalfopristin, ciprofloxacin, trimethoprim and sulphadiazine using Etest for MIC determination. Most of the isolates (140) originated from 39 dairy products (yoghurt, sour cream, fermented milk and cheese), while 49 were isolated directly from nine commercial cultures. The bacteria belonged to the genera Lactobacillus, Lactococcus, Leuconostoc and Streptococcus. Only one of the 189 isolates was classified as resistant to an antimicrobial agent included in the study. This isolate, a lactobacillus, was classified as high level resistant to streptomycin. The remaining isolates were not classified as resistant to the antimicrobial agents included other than to those they are known to have a natural reduced susceptibility to. Thus, starter culture bacteria in Norwegian dairy products do not seem to represent a source for spread of genes encoding resistance to antimicrobial agents.

Antimicrobial Treatment of Polymeric Medical Devices by Silver Nanomaterials and Related Technology

PubMed Central

Polívková, Markéta; Hubáček, Tomáš; Staszek, Marek; Švorčík, Václav; Siegel, Jakub

2017-01-01

Antimicrobial biocompatible polymers form a group of highly desirable materials in medicinal technology that exhibit interesting thermal and mechanical properties, and high chemical resistance. There are numerous types of polymers with antimicrobial activity or antimicrobial properties conferred through their proper modification. In this review, we focus on the second type of polymers, especially those whose antimicrobial activity is conferred by nanotechnology. Nanotechnology processing is a developing area that exploits the antibacterial effects of broad-scale compounds, both organic and inorganic, to form value-added medical devices. This work gives an overview of nanostructured antimicrobial agents, especially silver ones, used together with biocompatible polymers as effective antimicrobial composites in healthcare. The bactericidal properties of non-conventional antimicrobial agents are compared with those of conventional ones and the advantages and disadvantages are discussed. PMID:28212308

Antimicrobial Treatment of Polymeric Medical Devices by Silver Nanomaterials and Related Technology.

PubMed

Polívková, Markéta; Hubáček, Tomáš; Staszek, Marek; Švorčík, Václav; Siegel, Jakub

2017-02-15

Antimicrobial biocompatible polymers form a group of highly desirable materials in medicinal technology that exhibit interesting thermal and mechanical properties, and high chemical resistance. There are numerous types of polymers with antimicrobial activity or antimicrobial properties conferred through their proper modification. In this review, we focus on the second type of polymers, especially those whose antimicrobial activity is conferred by nanotechnology. Nanotechnology processing is a developing area that exploits the antibacterial effects of broad-scale compounds, both organic and inorganic, to form value-added medical devices. This work gives an overview of nanostructured antimicrobial agents, especially silver ones, used together with biocompatible polymers as effective antimicrobial composites in healthcare. The bactericidal properties of non-conventional antimicrobial agents are compared with those of conventional ones and the advantages and disadvantages are discussed.

Impact of formulary restriction with prior authorization by an antimicrobial stewardship program

PubMed Central

Reed, Erica E.; Stevenson, Kurt B.; West, Jessica E.; Bauer, Karri A.; Goff, Debra A.

2013-01-01

In an era of increasing antimicrobial resistance and few antimicrobials in the developmental pipeline, many institutions have developed antimicrobial stewardship programs (ASPs) to help implement evidence-based (EB) strategies for ensuring appropriate utilization of these agents. EB strategies for accomplishing this include formulary restriction with prior authorization. Potential limitations to this particular strategy include delays in therapy, prescriber pushback, and unintended increases in use of un-restricted antimicrobials; however, our ASP found that implementing prior authorization for select antimicrobials along with making a significant effort to educate clinicians on criteria for use ensured more appropriate prescribing of these agents, hopefully helping to preserve their utility for years to come. PMID:23154323

Impact of formulary restriction with prior authorization by an antimicrobial stewardship program.

PubMed

Reed, Erica E; Stevenson, Kurt B; West, Jessica E; Bauer, Karri A; Goff, Debra A

2013-02-15

In an era of increasing antimicrobial resistance and few antimicrobials in the developmental pipeline, many institutions have developed antimicrobial stewardship programs (ASPs) to help implement evidence-based (EB) strategies for ensuring appropriate utilization of these agents. EB strategies for accomplishing this include formulary restriction with prior authorization. Potential limitations to this particular strategy include delays in therapy, prescriber pushback, and unintended increases in use of un-restricted antimicrobials; however, our ASP found that implementing prior authorization for select antimicrobials along with making a significant effort to educate clinicians on criteria for use ensured more appropriate prescribing of these agents, hopefully helping to preserve their utility for years to come.

Bacteria from Animals as a Pool of Antimicrobial Resistance Genes

PubMed Central

Argudín, Maria Angeles; Deplano, Ariane; Meghraoui, Alaeddine; Dodémont, Magali; Heinrichs, Amelie; Denis, Olivier; Nonhoff, Claire; Roisin, Sandrine

2017-01-01

Antimicrobial agents are used in both veterinary and human medicine. The intensive use of antimicrobials in animals may promote the fixation of antimicrobial resistance genes in bacteria, which may be zoonotic or capable to transfer these genes to human-adapted pathogens or to human gut microbiota via direct contact, food or the environment. This review summarizes the current knowledge of the use of antimicrobial agents in animal health and explores the role of bacteria from animals as a pool of antimicrobial resistance genes for human bacteria. This review focused in relevant examples within the ESC(K)APE (Enterococcus faecium, Staphylococcus aureus, Clostridium difficile (Klebsiella pneumoniae), Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae) group of bacterial pathogens that are the leading cause of nosocomial infections throughout the world. PMID:28587316

Comparative In Vitro Susceptibilities and Bactericidal Activities of Investigational Fluoroquinolone ABT-492 and Other Antimicrobial Agents against Human Mycoplasmas and Ureaplasmas

PubMed Central

Waites, Ken B.; Crabb, Donna M.; Duffy, Lynn B.

2003-01-01

We determined in vitro susceptibilities for ABT-492 and other antimicrobials against Mycoplasma pneumoniae, Mycoplasma fermentans, Mycoplasma hominis, and Ureaplasma species. ABT-492 MICs were ≤1 μg/ml, and the agent was bactericidal against selected isolates of M. pneumoniae and M. hominis. ABT-492 has potential for treatment of infections due to these microorganisms. PMID:14638513

Effect of Plant Antimicrobial Agents Containing Marinades on Storage Stability and Microbiological Quality of Broiler Chicken Cuts Packed with Modified Atmosphere Packaging.

PubMed

Alakomi, H-L; Maukonen, J; Honkapää, K; Storgårds, E; Quirin, K-W; Yang, B; Saarela, M

2017-10-01

The food industry, including the meat industry, is currently looking for natural preservatives to prevent the growth of harmful microbes in foods. The potential of plant-derived antimicrobial extracts to increase the shelf life and to delay the microbiological spoilage of marinated broiler chicken cuts in modified atmosphere packages during cold storage was investigated in this study. We evaluated the impact of aqueous ethanolic extracts of Finnish sea buckthorn berries and lingonberries and supercritical CO 2 -extracted herbal extracts from an antimicrobial blend and oregano leaves on the shelf life of broiler meat. The commercial antimicrobial blend extract and the oregano extract inhibited the growth of lactic acid bacteria (LAB) and Brochothrix thermosphacta in the marinated samples. The antimicrobial blend extract also reduced the growth of psychrotrophic aerobic bacteria, whereas the sea buckthorn and lingonberry extracts did not. Only minor antimicrobial activity against Enterobacteriaceae by all the extracts was observed. Plate count analysis, denaturing gradient gel electrophoresis, and quantitative real-time PCR indicated that LAB, which are the major spoilage group in marinated modified atmosphere-packaged poultry products, were not significantly affected by the berry extracts studied. During this shelf-life study, LAB isolates of Lactobacillus and Leuconostoc were identified in the marinated samples. Antimicrobial blends and oregano leaf extracts can act as antimicrobial agents in marinade blends, although tailoring of the dose is needed because of their strong taste. Further studies for exploiting synergistic effects of plant extracts could contribute to the development of potential and more effective antimicrobial blends. Studies are needed in meat matrices and in product applications to demonstrate the efficacy of these compounds.

In vitro susceptibility of Bacillus spp. to selected antimicrobial agents.

PubMed Central

Weber, D J; Saviteer, S M; Rutala, W A; Thomann, C A

1988-01-01

Although often dismissed as contaminants when isolated from blood cultures, Bacillus spp. are increasingly recognized as capable of causing serious systemic infections. As part of a clinical-microbiological study, 89 strains of Bacillus spp. isolated from clinical blood cultures between 1981 and 1985 had their species determined and were tested for antimicrobial agent susceptibility to 18 antibiotics. Species of isolates were determined by the API 50CH and API 20E systems. Bacillus cereus (54 strains) was the most common species isolated, followed by B. megaterium (13 strains), B. polymyxa (5 strains), B. pumilus (4 strains), B. subtilis (4 strains), B. circulans (3 strains), B. amyloliquefaciens (2 strains), B. licheniformis (1 strain), and Bacillus spp. (3 strains). Microdilution MIC susceptibility tests revealed all B. cereus strains to be susceptible to imipenem, vancomycin, chloramphenicol, gentamicin, and ciprofloxacin. Non-B. cereus strains were most susceptible to imipenem, vancomycin, LY146032, and ciprofloxacin. Disk susceptibility testing suggested that B. cereus was rarely susceptible to penicillins, semisynthetic penicillins, or cephalosporins with the exception of mezlocillin. In contrast, many non-B. cereus strains were susceptible to penicillins, semisynthetic penicillins, and cephalosporins, but marked variability was noted among species. PMID:3395100

Antimicrobial Resistance Among Nontyphoidal Salmonella Isolated From Blood in the United States, 2003-2013.

PubMed

Angelo, Kristina M; Reynolds, Jared; Karp, Beth E; Hoekstra, Robert Michael; Scheel, Christina M; Friedman, Cindy

2016-11-15

 Salmonella causes an estimated 100 000 antimicrobial-resistant infections annually in the United States. Salmonella antimicrobial resistance may result in bacteremia and poor outcomes. We describe antimicrobial resistance among nontyphoidal Salmonella blood isolates, using data from the National Antimicrobial Resistance Monitoring System.  Human nontyphoidal Salmonella isolates from 2003 to 2013 were classified as fully susceptible, resistant to ≥1 antimicrobial agent, or resistant to a first-line agent. Logistic regression was used to compare resistance patterns, serotypes, and patient characteristics for Salmonella isolated from blood versus stool and to determine resistance trends over time.  Approximately 20% of blood isolates had antimicrobial resistance to a first-line treatment agent. Bacteremia was associated with male sex, age ≥65 years, and specific serotypes. Blood isolates were more likely to be resistant to ≥1 agent for serotypes Enteritidis, Javiana, Panama, and Typhimurium. Blood isolates were most commonly resistant to tetracycline (19%), and more likely resistant to a first-line agent (odds ratio, 1.81; 95% confidence interval, 1.56-2.11) than stool isolates. Ceftriaxone resistance increased in blood isolates from 2003 to 2013 (odd ratio, 1.12; 95% confidence interval, 1.02-1.22).  Resistance to first-line treatment agents in patients with Salmonella bacteremia is a concern for public health and for informing clinical decisions. Judicious antimicrobial use is crucial to limit resistance. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Antimicrobial Use and Antimicrobial Resistance: A Population Perspective

PubMed Central

Samore, Matthew H.

2002-01-01

The need to stem the growing problem of antimicrobial resistance has prompted multiple, sometimes conflicting, calls for changes in the use of antimicrobial agents. One source of disagreement concerns the major mechanisms by which antibiotics select resistant strains. For infections like tuberculosis, in which resistance can emerge in treated hosts through mutation, prevention of antimicrobial resistance in individual hosts is a primary method of preventing the spread of resistant organisms in the community. By contrast, for many other important resistant pathogens, such as penicillin-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus faecium resistance is mediated by the acquisition of genes or gene fragments by horizontal transfer; resistance in the treated host is a relatively rare event. For these organisms, indirect, population-level mechanisms of selection account for the increase in the prevalence of resistance. These mechanisms can operate even when treatment has a modest, or even negative, effect on an individual host’s colonization with resistant organisms. PMID:11971765

Triclosan antimicrobial polymers

PubMed Central

Petersen, Richard C.

2016-01-01

Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers that set on cooling

Antimicrobial susceptibility of Histophilus somni isolated from clinically affected cattle in Australia.

PubMed

Goldspink, Lauren K; Mollinger, Joanne L; Barnes, Tamsin S; Groves, Mitchell; Mahony, Timothy J; Gibson, Justine S

2015-02-01

This study investigated antimicrobial resistance traits, clonal relationships and epidemiology of Histophilus somni isolated from clinically affected cattle in Queensland and New South Wales, Australia. Isolates (n = 53) were subjected to antimicrobial susceptibility testing against six antimicrobial agents (ceftiofur, enrofloxacin, florfenicol, tetracycline, tilmicosin and tulathromycin) using disc diffusion and minimum inhibitory concentration (MIC) assays. Clonal relationships were assessed using repetitive sequence PCR and descriptive epidemiological analysis was performed. The H. somni isolates appeared to be geographically clonal, with 27/53 (47%) isolates grouping in one cluster from one Australian state. On the basis of disc diffusion, 34/53 (64%) isolates were susceptible to all antimicrobial agents tested; there was intermediate susceptibility to tulathromycin in 12 isolates, tilmicosin in seven isolates and resistance to tilmicosin in one isolate. Using MIC, all but one isolate was susceptible to all antimicrobial agents tested; the non-susceptible isolate was resistant to tetracycline, but this MIC result could not be compared to disc diffusion, since there are no interpretative guidelines for disc diffusion for H. somni against tetracycline. In this study, there was little evidence of antimicrobial resistance in H. somni isolates from Australian cattle. Disc diffusion susceptibility testing results were comparable to MIC results for most antimicrobial agents tested; however, results for isolates with intermediate susceptibility or resistance to tilmicosin and tulathromycin on disc diffusion should be interpreted with caution in the absence of MIC results. Copyright © 2014 Elsevier Ltd. All rights reserved.

Gallium(iii) and iron(iii) complexes of quinolone antimicrobials.

PubMed

Mjos, Katja Dralle; Cawthray, Jacqueline F; Polishchuk, Elena; Abrams, Michael J; Orvig, Chris

2016-08-16

Iron is an essential nutrient for many microbes. According to the "Trojan Horse Hypothesis", biological systems have difficulties distinguishing between Fe(3+) and Ga(3+), which constitutes the antimicrobial efficacy of the gallium(iii) ion. Nine novel tris(quinolono)gallium(iii) complexes and their corresponding iron(iii) analogs have been synthesized and fully characterized. Quinolone antimicrobial agents from three drug generations were used in this study: ciprofloxacin, enoxacin, fleroxacin, levofloxacin, lomefloxacin, nalidixic acid, norfloxacin, oxolinic acid, and pipemidic acid. The antimicrobial efficacy of the tris(quinolono)gallium(iii) complexes was studied against E. faecalis and S. aureus (both Gram-positive), as well as E. coli, K. pneumonia, and P. aeruginosa (all Gram-negative) in direct comparison to the tris(quinolono)iron(iii) complexes and the corresponding free quinolone ligands at various concentrations. For the tris(quinolono)gallium(iii) complexes, no combinational antimicrobial effects between Ga(3+) and the quinolone antimicrobial agents were observed.

Antimicrobial Lemongrass Essential Oil-Copper Ferrite Cellulose Acetate Nanocapsules.

PubMed

Liakos, Ioannis L; Abdellatif, Mohamed H; Innocenti, Claudia; Scarpellini, Alice; Carzino, Riccardo; Brunetti, Virgilio; Marras, Sergio; Brescia, Rosaria; Drago, Filippo; Pompa, Pier Paolo

2016-04-20

Cellulose acetate (CA) nanoparticles were combined with two antimicrobial agents, namely lemongrass (LG) essential oil and Cu-ferrite nanoparticles. The preparation method of CA nanocapsules (NCs), with the two antimicrobial agents, was based on the nanoprecipitation method using the solvent/anti-solvent technique. Several physical and chemical analyses were performed to characterize the resulting NCs and to study their formation mechanism. The size of the combined antimicrobial NCs was found to be ca. 220 nm. The presence of Cu-ferrites enhanced the attachment of LG essential oil into the CA matrix. The magnetic properties of the combined construct were weak, due to the shielding of Cu-ferrites from the polymeric matrix, making them available for drug delivery applications where spontaneous magnetization effects should be avoided. The antimicrobial properties of the NCs were significantly enhanced with respect to CA/LG only. This work opens novel routes for the development of organic/inorganic nanoparticles with exceptional antimicrobial activities.

[Antimicrobial susceptibility testing in clinically relevant non-fermenting gram-negative bacilli: recommendations from the Antimicrobial Agents Subcommittee of the Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas, Asociación Argentina de Microbiología].

PubMed

Radice, Marcela; Marín, Marcelo; Giovanakis, Marta; Vay, Carlos; Almuzara, Marisa; Limansky, Adriana; Casellas, José M; Famiglietti, Angela; Quinteros, Mirta; Bantar, Carlos; Galas, Marcelo; Kovensky Pupko, Jaime; Nicola, Federico; Pasterán, Fernando; Soloaga, Rolando; Gutkind, Gabriel

2011-01-01

This document contains the recommendations for antimicrobial susceptibility testing of the clinically relevant non-fermenting gram-negative bacilli (NFGNB), adopted after conforming those from international committees to the experience of the Antimicrobial Agents Subcommittee members and invited experts. This document includes an update on NFGNB classification and description, as well as some specific descriptions regarding natural or frequent antimicrobial resistance and a brief account of associated resistance mechanisms. These recommendations not only suggest the antimicrobial drugs to be evaluated in each case, but also provide an optimization of the disk diffusion layout and a selection of results to be reported. Finally, this document also includes a summary of the different methodological approaches that may be used for detection and confirmation of emerging b-lactamases, such as class A and B carbapenemases.

Tokyo Guidelines 2018: antimicrobial therapy for acute cholangitis and cholecystitis.

PubMed

Gomi, Harumi; Solomkin, Joseph S; Schlossberg, David; Okamoto, Kohji; Takada, Tadahiro; Strasberg, Steven M; Ukai, Tomohiko; Endo, Itaru; Iwashita, Yukio; Hibi, Taizo; Pitt, Henry A; Matsunaga, Naohisa; Takamori, Yoriyuki; Umezawa, Akiko; Asai, Koji; Suzuki, Kenji; Han, Ho-Seong; Hwang, Tsann-Long; Mori, Yasuhisa; Yoon, Yoo-Seok; Huang, Wayne Shih-Wei; Belli, Giulio; Dervenis, Christos; Yokoe, Masamichi; Kiriyama, Seiki; Itoi, Takao; Jagannath, Palepu; Garden, O James; Miura, Fumihiko; de Santibañes, Eduardo; Shikata, Satoru; Noguchi, Yoshinori; Wada, Keita; Honda, Goro; Supe, Avinash Nivritti; Yoshida, Masahiro; Mayumi, Toshihiko; Gouma, Dirk J; Deziel, Daniel J; Liau, Kui-Hin; Chen, Miin-Fu; Liu, Keng-Hao; Su, Cheng-Hsi; Chan, Angus C W; Yoon, Dong-Sup; Choi, In-Seok; Jonas, Eduard; Chen, Xiao-Ping; Fan, Sheung Tat; Ker, Chen-Guo; Giménez, Mariano Eduardo; Kitano, Seigo; Inomata, Masafumi; Mukai, Shuntaro; Higuchi, Ryota; Hirata, Koichi; Inui, Kazuo; Sumiyama, Yoshinobu; Yamamoto, Masakazu

2018-01-01

Antimicrobial therapy is a mainstay of the management for patients with acute cholangitis and/or cholecystitis. The Tokyo Guidelines 2018 (TG18) provides recommendations for the appropriate use of antimicrobials for community-acquired and healthcare-associated infections. The listed agents are for empirical therapy provided before the infecting isolates are identified. Antimicrobial agents are listed by class-definitions and TG18 severity grade I, II, and III subcategorized by clinical settings. In the era of emerging and increasing antimicrobial resistance, monitoring and updating local antibiograms is underscored. Prudent antimicrobial usage and early de-escalation or termination of antimicrobial therapy are now important parts of decision-making. What is new in TG18 is that the duration of antimicrobial therapy for both acute cholangitis and cholecystitis is systematically reviewed. Prophylactic antimicrobial usage for elective endoscopic retrograde cholangiopancreatography is no longer recommended and the section was deleted in TG18. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included. © 2018 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

Antimicrobial properties of conventional restorative filling materials and advances in antimicrobial properties of composite resins and glass ionomer cements-A literature review.

PubMed

Farrugia, Cher; Camilleri, Josette

2015-04-01

It has been reported that complete caries removal from cavities during restoration of teeth is difficult. Furthermore with the tissue saving approach it is expected that more of the saved affected tissue will possibly harbor more residual bacteria. Antimicrobial restorative filling materials would be ideal to prevent the spread of caries after completion of tooth restoration, thus preventing recurrent decay and eventually restoration failure. This paper reviews the literature on the antimicrobial properties of dental restorative filling materials. Pubmed searches on the antibacterial properties of restorative materials were carried out. Keywords were chosen to assess antibacterial properties of conventional filling materials. Methods of introducing antimicrobial agents in restorative materials were also reviewed together with the methodology used to assess antimicrobial activity. 174 articles from 1983 till 2014 were included. Adhesive materials have decreased antimicrobial activity when compared to amalgams and zinc oxides. Several techniques have been employed in order to increase the antimicrobial activity of restorative materials. Although antimicrobial activity of restorative materials is important, the introduction of antimicrobial agents/techniques should not be at the expense of other material properties. Environmental changes within a material may affect the bacterial response to the antimicrobial. Bacterial adhesion to the restorative materials should be assessed. Long term assessment of antimicrobial activity is important and is clinically relevant. The use of antimicrobial dental materials is important unless such characteristics are gained to the detriment of other material properties. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The US national antimicrobial resistance monitoring system.

PubMed

Gilbert, Jeffrey M; White, David G; McDermott, Patrick F

2007-10-01

The use of antimicrobial agents in food animals can select for resistant bacterial pathogens that may be transmitted to humans via the commercial meat supply. In the USA, the FDA's Center for Veterinary Medicine regulatory duties require a determination that antimicrobial drugs are safe and effective for use in food animals. In addition, a qualitative assessment of risks to human health from antimicrobial resistance requires development. This risk assessment process is supported by data generated by the FDA's National Antimicrobial Resistance Monitoring System (NARMS) for enteric bacteria. NARMS data on antimicrobial susceptibility among Salmonella, Campylobacter, Escherichia coli and Enterococcus is collected. Research activities defining the genetic bases of resistance helps to understand the potential public health risks posed by the spread of antimicrobial resistance from food animal antimicrobial use. These activities help insure that antimicrobials are used judiciously to promote human and animal health.

In vitro drug susceptibility of 40 international reference rapidly growing mycobacteria to 20 antimicrobial agents

PubMed Central

Pang, Hui; Li, Guilian; Wan, Li; Jiang, Yi; Liu, Haican; Zhao, Xiuqin; Zhao, Zhongfu; Wan, Kanglin

2015-01-01

Rapidly growing mycobacteria (RGM) are human pathogens that are relatively easily identified by acid-fast staining but are proving difficult to treat in the clinic. In this study, we performed susceptibility testing of 40 international reference RGM species against 20 antimicrobial agents using the cation-adjusted Mueller-Hinton (CAMH) broth microdilution based on the minimum inhibitory concentration (MIC) assay recommended by the guidelines of the Clinical and Laboratory Standards Institute (CLSI). The results demonstrated that RGM organisms were resistant to the majority of first-line antituberculous agents but not to second-line fluoroquinolones or aminoglycosides. Three drugs (amikacin, tigecycline and linezolid) displayed potent antimycobacterial activity against all tested strains. Capreomycin, levofloxacin and moxifloxacin emerged as promising candidates for the treatment of RGM infections, and cefoxitin and meropenem were active against most strains. Mycobacterium chelonae (M. chelonae), M. abscessus, M. bolletii, M. fortuitum, M. boenickei, M. conceptionense, M. pseudoshottsii, M. septicum and M. setense were the most resistant RGM species. These results provide significant insight into the treatment of RGM species and will assist optimization of clinical criteria. PMID:26629031

Role of Nutrients and Phyto-compounds in the Modulation of Antimicrobial Resistance.

PubMed

Harakeh, Steve; Khan, Imran; Almasaudi, Saad B; Azhar, Esam I; Al-Jaouni, Soad; Niedzweicki, Aleksandra

2017-01-01

Antimicrobial resistance is quickly spreading and has become a major public health problem worldwide. If this issue is not resolved, it may cause a shift back to the pre-antibiotics era and infectious disease will again be a serious problem, especially in developing countries. Since the discovery of antibiotics, bacterial resistance has emerged, enabling certain bacteria to withstand antibiotic action. The emergence of antibiotic resistance is fueled by excessive and improper use of antimicrobial agents, especially in developing countries. For this reason, alternatives to or modifications of current treatment methods have been sought. The aim of this review is to highlight the possible synergies of various agents that can augment antibiotic activities. A structured literature search was conducted using only papers that have been published in PubMed with the focus on the agents that are likely to modulate antimicrobial resistance. In this review, data was retrieved from the literature regarding the possible synergies that exist between commercially available antimicrobial drugs with agents of interest. The papers included were summarized and analyzed, critiqued and compared for their contents using a conceptual frame-work. In total, one hundred and twenty six papers were reviewed. The number of papers that dealt with the different topics included are as follows (): emergence of antimicrobial resistance (22), bioactive phyto-compounds (36) (phytobiologics, and phytochemicals), Antioxidants (40) (N-acetylcysteine, Ambroxol, Ascorbic acid, Glutathione and vitamin E), Peptide synergies (14) (Synthetic cationic α-helical AMPs, CopA3, Alafosfalin, PMAP-36, Phosphonopeptide L-norvalyl-L-1-aminoethylphosphonic acid and norcardicin-A), nano-antibiotics (10), drug-compound interactions (4).This review addressed the new strategies using the above compounds in the modulation of antimicrobial resistance to avoid issues related to resistance of bacteria to antibiotics. The

Adsorption of various antimicrobial agents to endotoxin removal polymyxin-B immobilized fiber (Toraymyxin®). Part 2: Adsorption of two drugs to Toraymyxin PMX-20R cartridges.

PubMed

Shimokawa, Ken-ichi; Takakuwa, Ryotaro; Wada, Yuko; Yamazaki, Noriko; Ishii, Fumiyoshi

2013-01-01

In our previous study, the degree of adsorption of 9 representative antimicrobial agents to Toraymyxin(®) PMX-F sheets was quantitatively evaluated. As a result, the adsorption rate was 22.1% for Linezolid in the presence of serum. Therefore, we investigated whether two types of antimicrobial agents (Ciprofroxacin and Linezolid) can be better adsorbed on PMX-F sheets. When the number of PMX-F sheets was increased in a step wise manner, specifically 2, 4, 6, 8 and 12, the adsorption rate increased linearly. In addition, the adsorption to polymyxin-B immobilized fiber (Toraymyxin(®) PMX-20R) cartridges, widely used to remove endotoxins from circulating blood in the treatment of sepsis, was quantitatively evaluated. As a result, in the presence of serum, Linezolid showed adsorption to PMX-20R, and the adsorption rate after 2h was 54.5%, and that after 4h was 65.8%. The results of this study suggest the necessity of monitoring blood antimicrobial concentration during treatment for sepsis with Linezolid, which showed adsorption to PMX-20R in an environment close to a clinical environment. Copyright © 2012 Elsevier B.V. All rights reserved.

Shigella Antimicrobial Drug Resistance Mechanisms, 2004-2014.

PubMed

Nüesch-Inderbinen, Magdalena; Heini, Nicole; Zurfluh, Katrin; Althaus, Denise; Hächler, Herbert; Stephan, Roger

2016-06-01

To determine antimicrobial drug resistance mechanisms of Shigella spp., we analyzed 344 isolates collected in Switzerland during 2004-2014. Overall, 78.5% of isolates were multidrug resistant; 10.5% were ciprofloxacin resistant; and 2% harbored mph(A), a plasmid-mediated gene that confers reduced susceptibility to azithromycin, a last-resort antimicrobial agent for shigellosis.

Antimicrobial agents from Licaria puchuri-major and their synergistic effect with polygodial.

PubMed

Himejima, M; Kubo, I

1992-05-01

The resistance of the seeds of Licaria puchuri-major (Lauraceae) to decomposition in nature seems to be due largely to chemical defense, since its n-hexane extract contains antimicrobial principles in quantity, with a broad antimicrobial spectrum. In order to identify the active principles, the n-hexane extract was steam-distilled to yield a distillate and a residue. Subsequent bioassay indicated that the distillate retained the original broad antimicrobial activity, while the residue exhibited almost no activity. Gc-ms analysis showed that the distillate contained four phenolic compounds, seven monoterpenes, and one sesquiterpene. In contrast, the residue contained, almost exclusively, lauric acid. In the detailed antimicrobial assay with the pure compounds identified, most of them showed broad, but moderate, antimicrobial activity. Some of the components identified in the distillate were combined with polygodial [1] in order to enhance their antifungal activity. Unexpectedly, while polygodial did not synergize the antifungal activity of any of the compounds tested, the antifungal activity of polygodial was significantly increased when combined with aromatic substances such as anethole, safrole, or methyleugenol.

Modeling antimicrobial tolerance and treatment of heterogeneous biofilms.

PubMed

Zhao, Jia; Seeluangsawat, Paisa; Wang, Qi

2016-12-01

A multiphasic, hydrodynamic model for spatially heterogeneous biofilms based on the phase field formulation is developed and applied to analyze antimicrobial tolerance of biofilms by acknowledging the existence of persistent and susceptible cells in the total population of bacteria. The model implements a new conversion rate between persistent and susceptible cells and its homogeneous dynamics is bench-marked against a known experiment quantitatively. It is then discretized and solved on graphic processing units (GPUs) in 3-D space and time. With the model, biofilm development and antimicrobial treatment of biofilms in a flow cell are investigated numerically. Model predictions agree qualitatively well with available experimental observations. Specifically, numerical results demonstrate that: (i) in a flow cell, nutrient, diffused in solvent and transported by hydrodynamics, has an apparent impact on persister formation, thereby antimicrobial persistence of biofilms; (ii) dosing antimicrobial agents inside biofilms is more effective than dosing through diffusion in solvent; (iii) periodic dosing is less effective in antimicrobial treatment of biofilms in a nutrient deficient environment than in a nutrient sufficient environment. This model provides us with a simulation tool to analyze mechanisms of biofilm tolerance to antimicrobial agents and to derive potentially optimal dosing strategies for biofilm control and treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Design of novel analogues of short antimicrobial peptide anoplin with improved antimicrobial activity.

PubMed

Wang, Yang; Chen, Jianbo; Zheng, Xin; Yang, Xiaoli; Ma, Panpan; Cai, Ying; Zhang, Bangzhi; Chen, Yuan

2014-12-01

Currently, novel antibiotics are urgently required to combat the emergence of drug-resistant bacteria. Antimicrobial peptides with membrane-lytic mechanism of action have attracted considerable interest. Anoplin, a natural α-helical amphiphilic antimicrobial peptide, is an ideal research template because of its short sequence. In this study, we designed and synthesized a group of analogues of anoplin. Among these analogues, anoplin-4 composed of D-amino acids displayed the highest antimicrobial activity due to increased charge, hydrophobicity and amphiphilicity. Gratifyingly, anoplin-4 showed low toxicity to host cells, indicating high bacterial selectivity. Furthermore, the mortality rate of mice infected with Escherichia coli was significantly reduced by anoplin-4 treatment relative to anoplin. In conclusion, anoplin-4 is a novel anoplin analogue with high antimicrobial activity and enzymatic stability, which may represent a potent agent for the treatment of infection. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.

Self-assembled arginine-rich peptides as effective antimicrobial agents.

PubMed

Mi, Gujie; Shi, Di; Herchek, Whitney; Webster, Thomas J

2017-04-01

Bacteria can adapt to their ever-changing environment to develop a resistance to commonly used antibiotics. This escalating evolution of bacteria coupled with a diminished number of effective antibiotics has caused a global healthcare crisis. New antimicrobials and novel approaches to tackle this problem are urgently needed. Antimicrobial peptides are of particular interest in this endeavor due to their broad spectrum antimicrobial properties as well as ability to combat multi-drug resistant bacteria. Most peptides have both hydrophobic and hydrophilic regions that enable them to be soluble in an aqueous solution, yet can insert into and subsequently disintegrate lipid rich membranes through diverse mechanisms. In this study, a novel class of cationic nanoparticles (formed by the self-assembly of an amphiphilic peptide) were shown to have strong antimicrobial properties against gram-positive bacteria, specifically Staphylococcus aureus, Staphylococcus epidermidis, and methicillin-resistant Staphylococcus aureus (MRSA) with minimal toxicity to human dermal fibroblasts. The particular self-assembled structure tested here included an arginine rich nanoparticle (C 17 H 35 GR7RGDS or amphiphilic peptide nanoparticles, APNPs) which incorporated seven arginine residues (imparting a positive charge to improve membrane interactions), a hydrophobic block which drove the self-assembly process, and the presence of an amino acid quadruplet arginine-glycine-aspartic acid-serine (RGDS) which may render these nanoparticles capable of attracting healthy cells while competing bacterial adherence to fibronectin, an adhesive protein found on cell surfaces. As such, this in vitro study demonstrated that the presently formulated APNPs should be further studied for a wide range of antibacterial applications where antibiotics are no longer useful. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1046-1054, 2017. © 2017 Wiley Periodicals, Inc.

Sulfur and sulfur nanoparticles as potential antimicrobials: from traditional medicine to nanomedicine.

PubMed

Rai, Mahendra; Ingle, Avinash P; Paralikar, Priti

2016-10-01

The alarming rate of infections caused by various pathogens and development of their resistance towards a large number of antimicrobial agents has generated an essential need to search for novel and effective antimicrobial agents. Metal nanoparticles such as silver have been widely used and accepted as strong antimicrobial agents, but considering the cost effectiveness and significant bioactivities, researchers are looking to utilize sulfur nanoparticles as an effective alternative to silver nanoparticles. This review has been focused on different approaches for the synthesis of sulfur nanoparticles, their broad spectrum bioactivities and possible mechanisms involved in their bioactivities. Expert commentary: Sulfur nanoparticles are reported to possess broad spectrum antimicrobial activity, and hence can be used to treat microbial infections and potentially tackle the problem of antibiotic resistance. Thus, in the future, sulfur nanoparticles can be used as an effective, non-toxic and economically viable alternative to other precious metal nanoparticles.

Multiple Antimicrobial Resistance of Escherichia coli Isolated from Chickens in Iran

PubMed Central

Talebiyan, Reza; Kheradmand, Mehdi; Khamesipour, Faham; Rabiee-Faradonbeh, Mohammad

2014-01-01

Antimicrobial agents are used extremely in order to reduce the great losses caused by Escherichia coli infections in poultry industry. In this study, 318 pathogenic Escherichia coli (APEC) strains isolated from commercial broiler flocks with coli-septicemia were examined for antimicrobials of both veterinary and human significance by disc diffusion method. Multiple resistances to antimicrobial agents were observed in all the isolates. Resistance to the antibiotics was as follows: Tylosin (88.68%), Erythromycin (71.70%), Oxytetracycline (43.40%), Sulfadimethoxine-Trimethoprim (39.62%), Enrofloxacin (37.74%), Florfenicol (35.85%), Chlortetracycline (33.96%), Doxycycline (16.98%), Difloxacin (32.08%), Danofloxacin (28.30%), Chloramphenicol (20.75%), Ciprofloxacin (7.55%), and Gentamicin (5.66%). This study showed resistance against the antimicrobial agents that are commonly applied in poultry, although resistance against the antibiotics that are only applied in humans or less frequently used in poultry was significantly low. This study emphasizes on the occurrence of multiple drug resistant E. coli among diseased broiler chickens in Iran. The data revealed the relative risks of using antimicrobials in poultry industry. It also concluded that use of antibiotics must be limited in poultry farms in order to reduce the antibiotic resistances. PMID:25548716

Multiple Antimicrobial Resistance of Escherichia coli Isolated from Chickens in Iran.

PubMed

Talebiyan, Reza; Kheradmand, Mehdi; Khamesipour, Faham; Rabiee-Faradonbeh, Mohammad

2014-01-01

Antimicrobial agents are used extremely in order to reduce the great losses caused by Escherichia coli infections in poultry industry. In this study, 318 pathogenic Escherichia coli (APEC) strains isolated from commercial broiler flocks with coli-septicemia were examined for antimicrobials of both veterinary and human significance by disc diffusion method. Multiple resistances to antimicrobial agents were observed in all the isolates. Resistance to the antibiotics was as follows: Tylosin (88.68%), Erythromycin (71.70%), Oxytetracycline (43.40%), Sulfadimethoxine-Trimethoprim (39.62%), Enrofloxacin (37.74%), Florfenicol (35.85%), Chlortetracycline (33.96%), Doxycycline (16.98%), Difloxacin (32.08%), Danofloxacin (28.30%), Chloramphenicol (20.75%), Ciprofloxacin (7.55%), and Gentamicin (5.66%). This study showed resistance against the antimicrobial agents that are commonly applied in poultry, although resistance against the antibiotics that are only applied in humans or less frequently used in poultry was significantly low. This study emphasizes on the occurrence of multiple drug resistant E. coli among diseased broiler chickens in Iran. The data revealed the relative risks of using antimicrobials in poultry industry. It also concluded that use of antibiotics must be limited in poultry farms in order to reduce the antibiotic resistances.

The effect of radiopacifiers agents on pH, calcium release, radiopacity, and antimicrobial properties of different calcium hydroxide dressings.

PubMed

Ordinola-Zapata, Ronald; Bramante, Clovis Monteiro; García-Godoy, Franklin; Moldauer, Bertram Ivan; Gagliardi Minotti, Paloma; Tercília Grizzo, Larissa; Duarte, Marco Antonio Hungaro

2015-07-01

The aim of this study was to evaluate the antimicrobial activity, pH level, calcium ion release, and radiopacity of calcium hydroxide pastes associated with three radiopacifying agents (iodoform, zinc oxide, and barium sulfate). For the pH and calcium release tests, 45 acrylic teeth were utilized and immersed in ultrapure water. After 24 h, 72 h, and 7 days the solution was analyzed by using a pH meter and an atomic absorption spectrophotometer. Polyethylene tubes filled with the pastes were used to perform the radiopacity test. For the antimicrobial test, 25 dentin specimens were infected intraorally in order to induce the biofilm colonization and treated with the pastes for 7 days. The Live/Dead technique and a confocal microscope were used to obtain the ratio of live cells. Parametric and nonparametric statistical tests were performed to show differences among the groups (P < 0.05). The pH analysis at 7 days showed significant differences (P < 0.05) among the groups. No differences among the pastes were found in the calcium release test on the 7th day (P > 0.05). The calcium hydroxide/iodoform samples had the highest radiopacity and antimicrobial activity against the biofilm-infected dentin in comparison to the other pastes (P < 0.05). Calcium hydroxide mixed with 17% iodoform and 35% propylene glycol into a paste had the highest pH, calcium ion release, radiopacity, and the greatest antimicrobial action versus similar samples mixed with BaSO4 or ZnO. © 2015 Wiley Periodicals, Inc.

Cytotoxicity of topical antimicrobial agents used in burn wounds in Australasia.

PubMed

Fraser, John F; Cuttle, Leila; Kempf, Margit; Kimble, Roy M

2004-03-01

Burn sepsis is a leading cause of mortality and morbidity in patients with major burns. The use of topical antimicrobial agents has helped improve the survival of these patients. Silvazine (Sigma Pharmaceuticals, Melbourne, Australia) (1% silver sulphadiazine and 0.2% chlorhexidine digluconate) is used exclusively in Australasia, and there is no published study on its cytotoxicity. This study compared the relative cytotoxicity of Silvazine with 1% silver sulphadiazine (Flamazine (Smith & Nephew Healthcare, Hull, UK)) and a silver-based dressing (Acticoat (Smith & Nephew Healthcare, Hull, UK)). Dressings were applied to the centre of culture plates that were then seeded with keratinocytes at an estimated 25% confluence. The plates were incubated for 72 h and culture medium and dressings then removed. Toluidine blue was added to stain the remaining keratinocytes. Following removal of the dye, the plates were photographed under standard conditions and these digital images were analysed using image analysis software. Data was analysed using Student's t-test. In the present study, Silvazine is the most cytotoxic agent. Seventy-two hour exposure to Silvazine in the present study results in almost no keratinocyte survival at all and a highly statistically significant reduction in cell survival relative to control, Acticoat and Flamazine (P<0.001, P<0.01, P<0.01, respectively). Flamazine is associated with a statistically significant reduction in cell numbers relative to control (P<0.05), but is much less cytotoxic than Silvazine (P<0.005). In this in-vitro study comparing Acticoat, Silvazine and Flamazine, Silvazine shows an increased cytotoxic effect, relative to control, Flamazine and Acticoat. An in-vivo study is required to determine whether this effect is carried into the clinical setting.

Synthesis, evaluation and modeling of some triazolothienopyrimidinones as anti-inflammatory and antimicrobial agents.

PubMed

Bekhit, Adnan A; Farghaly, Ahmed M; Shafik, Ragab M; Elsemary, Mona Ma; El-Shoukrofy, Mai S; Bekhit, Alaa El-Din A; Ibrahim, Tamer M

2017-06-01

New triazolotetrahydrobenzothienopyrimidinone derivatives were synthesized. Their structures were confirmed, and their anti-inflammatory, antimicrobial activities and ulcerogenic potentials were evaluated. Compounds 7a, 10a and 11a showed minimal ulcerogenic effect and high selectivity toward human recombinant COX-2 over COX-1 enzyme with IC 50 values of 1.39, 1.22 and 0.56 μM, respectively. Their docking outcome correlated with their biological activity and confirmed the high selectivity binding toward COX-2. Compound 12b displayed antimicrobial activity comparable to that of ampicillin against Escherichia coli while compounds 6 and 11c were similar to ampicillin against Staphylococcus aureus. In addition, compounds 7a, 9a, 10b and 11c showed dual anti-inflammatory/antimicrobial activities. This work represents a promising matrix for developing new potential anti-inflammatory, antimicrobial and dual antimicrobial/anti-inflammatory candidates. [Formula: see text].

Current Trend of Antimicrobial Prescription for Oral Implant Surgery Among Dentists in India.

PubMed

Datta, Rahul; Grewal, Yasmin; Batth, J S; Singh, Amandeep

2014-12-01

The aim of our study was to evaluate antimicrobial prescription behaviour amongst dentists performing oral implant surgery in India. Dentists performing oral implant surgery from different parts of India were personally approached during various national events such as conferences and academic meetings and information regarding their prescription habits for antimicrobial agents in routine oral implant surgery was collected using a structured questionnaire. Out of a total sample of 332 dentists, 85.5 % prescribed 17 different groups or combinations of antibiotics routinely for oral implant surgery in the normal healthy patient. Majority preferred the peri-operative protocol of drug therapy (72.2 %) with variable and prolonged duration of therapy after surgery, ranging from 3 to 10 days. An antimicrobial mouthwash was routinely prescribed by all the doctors (14.5 %) not in favour of prescribing antimicrobials in a normal healthy patient. Our findings suggest that there is a trend of antimicrobial agent misuse by dentists performing oral implant surgery in India, both in terms of drugs used and the protocols prescribed. The majority of these dentists prescribed a variety of antimicrobial agents for prolonged durations routinely even in the normal, healthy patients.

Introduction: the goals of antimicrobial therapy.

PubMed

Song, Jae-Hoon

2003-03-01

Antimicrobial agents are generally evaluated in preclinical studies assessing in vitro activity, animal models demonstrating in vivo bacteriologic efficacy, and clinical trials primarily investigating safety and clinical efficacy. However, large sample sizes are required to detect any differences in outcomes between antimicrobials in clinical trials, and, generally, studies are powered to show only clinical equivalence. In addition, diagnosis is often based on clinical symptoms, rather than microbiological evidence of bacterial infection, and the patients most likely to have resistant pathogens are often excluded. Clinical efficacy can be achieved in some bacterial infections in which antimicrobials are suboptimal or even not prescribed. However, bacterial eradication maximizes clinical efficacy and may also reduce the development and spread of resistant organisms. The goal of antimicrobial therapy is, therefore, to eradicate bacteria at the site of infection. Bacterial eradication is not usually assessed as a primary endpoint within the limits of currently recommended clinical trial design. However, pharmacokinetic (PK) (serum concentration profiles, penetration to site of infection) and pharmacodynamic (PD) (susceptibility, concentration- versus time-dependent killing, post-antimicrobial effects) criteria can be used to predict bacteriologic efficacy. PK/PD predictions should be confirmed during all phases of antimicrobial development and throughout clinical use in response to changing patterns of resistance. A clear rationale for dose recommendations can be determined preclinically based on PK/PD parameters, and correlated with efficacy, safety and resistance endpoints in clinical trials. The duration of treatment and dose should be the shortest that will reliably eradicate the pathogen(s), and that is safe and well tolerated. Currently available agents vary significantly in their ability to achieve PK/PD parameters necessary for bacteriologic eradication

Associations between host characteristics and antimicrobial resistance of Salmonella typhimurium.

PubMed

Ruddat, I; Tietze, E; Ziehm, D; Kreienbrock, L

2014-10-01

A collection of Salmonella Typhimurium isolates obtained from sporadic salmonellosis cases in humans from Lower Saxony, Germany between June 2008 and May 2010 was used to perform an exploratory risk-factor analysis on antimicrobial resistance (AMR) using comprehensive host information on sociodemographic attributes, medical history, food habits and animal contact. Multivariate resistance profiles of minimum inhibitory concentrations for 13 antimicrobial agents were analysed using a non-parametric approach with multifactorial models adjusted for phage types. Statistically significant associations were observed for consumption of antimicrobial agents, region type and three factors on egg-purchasing behaviour, indicating that besides antimicrobial use the proximity to other community members, health consciousness and other lifestyle-related attributes may play a role in the dissemination of resistances. Furthermore, a statistically significant increase in AMR from the first study year to the second year was observed.

Biofilm disruption with rotating microrods enhances antimicrobial efficacy

NASA Astrophysics Data System (ADS)

Mair, Lamar O.; Nacev, Aleksandar; Hilaman, Ryan; Stepanov, Pavel Y.; Chowdhury, Sagar; Jafari, Sahar; Hausfeld, Jeffrey; Karlsson, Amy J.; Shirtliff, Mark E.; Shapiro, Benjamin; Weinberg, Irving N.

2017-04-01

Biofilms are a common and persistent cause of numerous illnesses. Compared to planktonic microbes, biofilm residing cells often demonstrate significant resistance to antimicrobial agents. Thus, methods for dislodging cells from the biofilm may increase the antimicrobial susceptibility of such cells, and serve as a mechanical means of increasing antimicrobial efficacy. Using Aspergillus fumigatus as a model microbe, we magnetically rotate microrods in and around biofilm. We show that such rods can improve the efficacy of antimicrobial Amphotericin B treatments in vitro. This work represents a first step in using kinetic magnetic particle therapy for disrupting fungal biofilms.

Synthetic biology of antimicrobial discovery.

PubMed

Zakeri, Bijan; Lu, Timothy K

2013-07-19

Antibiotic discovery has a storied history. From the discovery of penicillin by Sir Alexander Fleming to the relentless quest for antibiotics by Selman Waksman, the stories have become like folklore used to inspire future generations of scientists. However, recent discovery pipelines have run dry at a time when multidrug-resistant pathogens are on the rise. Nature has proven to be a valuable reservoir of antimicrobial agents, which are primarily produced by modularized biochemical pathways. Such modularization is well suited to remodeling by an interdisciplinary approach that spans science and engineering. Herein, we discuss the biological engineering of small molecules, peptides, and non-traditional antimicrobials and provide an overview of the growing applicability of synthetic biology to antimicrobials discovery.

Antimicrobial activity of spices.

PubMed

Arora, D S; Kaur, J

1999-08-01

Spices have been shown to possess medicinal value, in particular, antimicrobial activity. This study compares the sensitivity of some human pathogenic bacteria and yeasts to various spice extracts and commonly employed chemotherapeutic substances. Of the different spices tested only garlic and clove were found to possess antimicrobial activity. The bactericidal effect of garlic extract was apparent within 1 h of incubation and 93% killing of Staphylococcus epidermidis and Salmonella typhi was achieved within 3 h. Yeasts were totally killed in 1 h by garlic extract but in 5 h with clove. Some bacteria showing resistance to certain antibiotics were sensitive to extracts of both garlic and clove. Greater anti-candidal activity was shown by garlic than by nystatin. Spices might have a great potential to be used as antimicrobial agents.

Antimicrobial resistance of Listeria spp. recovered from processed bison.

PubMed

Li, Q; Sherwood, J S; Logue, C M

2007-01-01

The current study examined the antimicrobial susceptibility of 86 Listeria spp. isolated from processed bison carcasses. Susceptibility to 25 antimicrobial agents was determined using E-test and National Antimicrobial Resistance Monitoring System (NARMS) panels. Most Listeria isolates (88-98%) exhibited resistance to bacitracin, oxacillin, cefotaxime, and fosfomycin. Resistance to tetracycline (18.6%) was also common. Of the 16 tetracycline-resistant Listeria isolates, 15 carried tetM and 2 contained integrase of Tn1545 transposons. Rifampicin and trimethoprim-sulfamethoxazole were the most active antimicrobial agents against Listeria spp., with a MIC(90) of 0.38 microg ml(-1). Ampicillin, erythromycin, penicillin, gentamicin, and tobramycin also exhibited good activity against Listeria spp., with MIC(90) not exceeding 1 microg ml(-1). Differences in resistance among Listeria spp. was displayed, as Listeria innocua strains were more resistant than other Listeria species. The study showed that Listeria monocytogenes strains from bison were susceptible to the antibiotics most commonly used to treat human listeriosis. However, the presence of antimicrobial resistance in L. innocua indicates the potential for transfer of resistance and a conjugative transposon to L. monocytogenes. The findings of our study will provide useful information for the development of public health policy in the use of antimicrobials in food animal production.

Antimicrobial Effects of 7,8-Dihydroxy-6-Methoxycoumarin and 7-Hydroxy-6-Methoxycoumarin Analogues against Foodborne Pathogens and the Antimicrobial Mechanisms Associated with Membrane Permeability.

PubMed

Yang, Ji-Yeon; Park, Jun-Hwan; Lee, Myung-Ji; Lee, Ji-Hoon; Lee, Hoi-Seon

2017-10-03

The antimicrobial effects of 7,8-dihydroxy-6-methoxycoumarin and 7-hydroxy-6-methoxycoumarin isolated from Fraxinus rhynchophylla bark and of their structural analogues were determined in an attempt to develop natural antimicrobial agents against the foodborne pathogens Escherichia coli, Bacillus cereus, Staphylococcus intermedius, and Listeria monocytogenes. To elucidate the relationship between structure and antimicrobial activity for the coumarin analogues, isolated constituents and their structural analogues were evaluated against foodborne pathogens. Based on the culture plate inhibition zones and MICs, 6,7-dimethoxycoumarin, 7,8-dihydroxy-6-methoxycoumarin, 7-hydroxy-6-methoxycoumarin, and 7-methoxycoumarin, containing a methoxy functional group on the coumarin skeleton, had the notable antimicrobial activity against foodborne pathogens. However, 7-hydroxycoumarin and 6,7-dihydroxycoumarin, which contained a hydroxyl functional group on the coumarin skeleton, had no antimicrobial activity against these pathogens. An increase in cell membrane permeability was confirmed by electron microscopy observations, and release of extracellular ATP and cell constituents followed treatment with the ethyl acetate fraction of F. rhynchophylla extract. These findings indicate that F. rhynchophylla extract and coumarin analogues have potential for use as antimicrobial agents against foodborne pathogens and that the antimicrobial mechanisms are associated with the loss of cell membrane integrity.

Methylsulfonyl benzothiazoles (MSBT) derivatives: Search for new potential antimicrobial and anticancer agents.

PubMed

Lad, Nitin P; Manohar, Yogesh; Mascarenhas, Malcolm; Pandit, Yashwant B; Kulkarni, Mahesh R; Sharma, Rajiv; Salkar, Kavita; Suthar, Ashish; Pandit, Shivaji S

2017-03-01

A series of novel 4 and 5-substituted methylsulfonyl benzothiazole (MSBT) compounds having amide, alkoxy, sulfonamide, nitro and amine functionality were synthesized from sequential reactions on 5-ethoxy-2-(methylsulfonyl)benzo[d]thiazole such as nitration, reduction, sulfonation, dealkylation, etc. All synthesized compounds were screened against antimicrobial and selected screened for anticancer activity. Antimicrobial activities studies reveled that among all compounds screened, out of MSBT-07, MSBT-11, MSBT-12, MSBT-14, MSBT-19, and MSBT-27 were found to have promising antimicrobial activity at MIC range of 4-50μg/ml against selected bacterial as well as fungal species. Compounds having good antimicrobial activity were screened for cervical cancer (HeLA cell lines). Of these MSBT-07 and MSBT-12 significantly reduced the cell growth. Consequently their calculated GI 50 values were found to be 0.1 or <0.1μM. Copyright © 2016 Elsevier Ltd. All rights reserved.

Prophylaxis of post-ERC infectious complications in patients with biliary obstruction by adding antimicrobial agents into ERC contrast media- a single center retrospective study.

PubMed

Wobser, Hella; Gunesch, Agnetha; Klebl, Frank

2017-01-13

Patients with biliary obstruction are at high risk to develop septic complications after endoscopic retrograde cholangiography (ERC). We evaluated the benefits of local application of antimicrobial agents into ERC contrast media in preventing post-ERC infectious complications in a high-risk study population. Patients undergoing ERC at our tertiary referral center were retrospectively included. Addition of vancomycin, gentamicin and fluconazol into ERC contrast media was evaluated in a case-control design. Outcomes comprised infectious complications within 3 days after ERC. In total, 84 ERC cases were analyzed. Primarily indications for ERC were sclerosing cholangitis (75%) and malignant stenosis (9.5%). Microbial testing of collected bile fluid in the treatment group was positive in 91.4%. Detected organisms were sensitive to the administered antimicrobials in 93%. The use of antimicrobials in contrast media was associated with a significant decrease in post-ERC infectious complications compared to non-use (14.3% vs. 33.3%; odds ratio [OR]: 0.33, 95% confidence interval [CI]: 0.114-0.978). After adjusting for the variables acute cholangitis prior to ERC and incomplete biliary drainage, the beneficial effect of intraductal antibiotic prophylaxis was even more evident (OR = 0.153; 95% CI: 0.039-0.598, p = 0.007). Patients profiting most obviously from intraductal antimicrobials were those with secondary sclerosing cholangitis. Local application of a combination of antibiotic and antimycotic agents to ERC contrast media efficiently reduced post-ERC infectious events in patients with biliary obstruction. This is the first study that evaluates ERC-related infectious complications in patients with secondary sclerosing cholangitis. Our first clinical results should now be prospectively evaluated in a larger patient cohort to improve the safety of ERC, especially in patients with secondary sclerosing cholangitis.

Antimicrobial activity of transition metal acid MoO(3) prevents microbial growth on material surfaces.

PubMed

Zollfrank, Cordt; Gutbrod, Kai; Wechsler, Peter; Guggenbichler, Josef Peter

2012-01-01

Serious infectious complications of patients in healthcare settings are often transmitted by materials and devices colonised by microorganisms (nosocomial infections). Current strategies to generate material surfaces with an antimicrobial activity suffer from the consumption of the antimicrobial agent and emerging multidrug-resistant pathogens amongst others. Consequently, materials surfaces exhibiting a permanent antimicrobial activity without the risk of generating resistant microorganisms are desirable. This publication reports on the extraordinary efficient antimicrobial properties of transition metal acids such as molybdic acid (H(2)MoO(4)), which is based on molybdenum trioxide (MoO(3)). The modification of various materials (e.g. polymers, metals) with MoO(3) particles or sol-gel derived coatings showed that the modified materials surfaces were practically free of microorganisms six hours after contamination with infectious agents. The antimicrobial activity is based on the formation of an acidic surface deteriorating cell growth and proliferation. The application of transition metal acids as antimicrobial surface agents is an innovative approach to prevent the dissemination of microorganisms in healthcare units and public environments. Copyright © 2011 Elsevier B.V. All rights reserved.

Qualitative screening of veterinary anti-microbial agents in tissues, milk, and eggs of food-producing animals using liquid chromatography coupled with tandem mass spectrometry.

PubMed

Chen, Dongmei; Yu, Jie; Tao, Yanfei; Pan, Yuanhu; Xie, Shuyu; Huang, Lingli; Peng, Dapeng; Wang, Xu; Wang, Yulian; Liu, Zhenli; Yuan, Zonghui

2016-04-01

A method for the analysis of 120 drugs in animal derived food was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These analytes belong to 12 families of veterinary anti-microbial agents (quinolones, macrolides, β-lactams, nitroimidazoles, sulfonamides, lincomycines, chloramphenicols, quinoxalines, tetracyclines, polypeptides, and antibacterial synergists) as well as other compounds not assigned to a particular drug family. The animal derived food samples include muscle and liver of swine, bovine, sheep, and chicken, as well as hen eggs and dairy milk. The sample preparation included ultrasound-assisted extraction (UAE) with acetonitrile-water and a final clean-up with auto solid-phase extraction (SPE) on HLB cartridges. The detection and quantification of 120 anti-microbial agents was performed using LC-MS/MS in positive and negative ion mode. The chromatographic separation was performed on a C18 column using acetonitrile and 0.1% formic acid as the mobile phase. The limit of detection (LOD) and limit of quantification (LOQ) of all drugs in food-producing animals were 0.5-3.0μg/kg and 1.5-10.0μg/kg, respectively. The developed method was successfully utilized to monitor real samples, which demonstrated that it is a simple, fast, and robust method, and could be used as a regulatory to screen for the presence of residues from veterinary anti-microbial drugs in animal-derived foods. Copyright © 2016 Elsevier B.V. All rights reserved.

Control of the development and prevalence of antimicrobial resistance in bacteria of food animal origin in Japan: a new approach for risk management of antimicrobial veterinary medicinal products in Japan.

PubMed

Asai, Tetsuo; Hiki, Mototaka; Ozawa, Manao; Koike, Ryoji; Eguchi, Kaoru; Kawanishi, Michiko; Kojima, Akemi; Endoh, Yuuko S; Hamamoto, Shuichi; Sakai, Masato; Sekiya, Tatsuro

2014-03-01

Antimicrobial agents are essential for controlling bacterial disease in food-producing animals and contribute to the stable production of safe animal products. The use of antimicrobial agents in these animals affects the emergence and prevalence of antimicrobial resistance in bacteria isolated from animals and animal products. As disease-causing bacteria are often transferred from food-producing animals to humans, the food chain is considered a route of transmission for the resistant bacteria and/or resistance genes. The Food Safety Commission of Japan (FSC) has been assessing the risk posed to human health by the transmission of antimicrobial-resistant bacteria from livestock products via the food chain. In addition to the FSC's risk assessments, the Japanese Ministry of Agriculture, Forestry and Fisheries has developed risk-management guidelines to determine feasible risk-management options for the use of antimicrobial veterinary medicinal products during farming practices. This report includes information on risk assessment and novel approaches for risk management of antimicrobial veterinary medicinal products for mitigating the risk of development and prevalence of antimicrobial resistance in bacteria originating from food-producing animals in Japan.

Sales of veterinary antibacterial agents in nine European countries during 2005-09: trends and patterns.

PubMed

Grave, Kari; Greko, Christina; Kvaale, Mari K; Torren-Edo, Jordi; Mackay, David; Muller, Arno; Moulin, Gerard

2012-12-01

To identify trends and patterns of sales of veterinary antimicrobial agents in nine European countries during 2005-09 in order to document the situation. Existing sales data, in tonnes of active ingredients, of veterinary antimicrobial agents by class were collected from nine European countries in a standardized manner for the years 2005-09 (one country for 2006-09). A population correction unit (PCU) is introduced as a proxy for the animal population potentially treated with antimicrobial agents. The sales data are expressed as mg of active substance/PCU. Data coverage was reported to be 98%-100% for the nine countries. Overall, sales of veterinary antimicrobials agents, in mg/PCU, declined during the reporting period in the nine countries. Substantial differences in the sales patterns and in the magnitude of sales of veterinary antimicrobial agents, expressed as mg/PCU, between the nine countries are observed. The major classes sold were penicillins, sulphonamides and tetracyclines. The sales accounted for by the various veterinary antimicrobial agents have changed substantially for most countries. An increase in the sales of third- and fourth-generation cephalosporins and fluoroquinolones were observed for the majority of the countries. Through re-analysis of existing data by application of a harmonized approach, an overall picture of the trends in the sales of veterinary antimicrobial agents in the nine countries was obtained. Notable differences in trends in sales between the countries were observed. Further studies, preferably including data by animal species, are needed to understand the factors that explain these observations.

Synthetic biology of antimicrobial discovery

PubMed Central

Zakeri, Bijan; Lu, Timothy K.

2012-01-01

Antibiotic discovery has a storied history. From the discovery of penicillin by Sir Alexander Fleming to the relentless quest for antibiotics by Selman Waksman, the stories have become like folklore, used to inspire future generations of scientists. However, recent discovery pipelines have run dry at a time when multidrug resistant pathogens are on the rise. Nature has proven to be a valuable reservoir of antimicrobial agents, which are primarily produced by modularized biochemical pathways. Such modularization is well suited to remodeling by an interdisciplinary approach that spans science and engineering. Herein, we discuss the biological engineering of small molecules, peptides, and non-traditional antimicrobials and provide an overview of the growing applicability of synthetic biology to antimicrobials discovery. PMID:23654251

Evaluating the antimicrobial activity of Nisin, Lysozyme and Ethylenediaminetetraacetate incorporated in starch based active food packaging film.

PubMed

Bhatia, Sugandha; Bharti, Anoop

2015-06-01

The pleothera of micro organisms obtained from contaminated food cultured in a starch broth was effectively tested against antibacterial agents, i.e. nisin, lysozyme and chelating agent EDTA. A variety of combination treatments of these antimicrobial agents and their incorporation in Starch based active packaging film according to their permissibility standards was done. 4 variables of Nisin concentration (ranging from 0 to 750 IU/ml), 3 variables of lysozyme concentration (ranging from 0 to 500 IU/ml) and 3 variables of EDTA concentration from (0 to 20 μM) were chosen. Bacterial inhibition by combination of different levels of different factors without antimicrobial films was evaluated using a liquid incubation method. The samples were assayed for turbidity at interval of 2, 4 and 24 h to check effectiveness of combined effects of antimicrobial agents which proved a transitory bactericidal effect for short incubation times. Zone of Inhibition was observed in the antimicrobial films prepared by agar diffusion method. Statistical analysis of experimental data for their antimicrobial spectrum was carried out by multi regression analysis and ANOVA using Design-Expert software to plot the final equation in terms of coded factors as antimicrobial agents. The experimental data indicated that the model was highly significant. Results were also evaluated graphically using response surface showing interactions between two factors, keeping other factor fixed at values at the center of domain. Synergy was also determined among antibacterial agents using the fractional inhibitory concentration (FIC) index which was observed to be 0.56 supporting the hypothesis that nisin and EDTA function as partial synergistically. The presented work aimed to screen in quick fashion the combinatorial effect of three antimicrobial agents and evaluating their efficacy in anti microbial film development.

Antimicrobial Drug Use and Resistance in Europe

PubMed Central

van de Sande-Bruinsma, Nienke; Verloo, Didier; Tiemersma, Edine; Monen, Jos; Goossens, Herman; Ferech, Matus

2008-01-01

Our study confronts the use of antimicrobial agents in ambulatory care with the resistance trends of 2 major pathogens, Streptococcus pneumoniae and Escherichia coli, in 21 European countries in 2000–2005 and explores whether the notion that antimicrobial drug use determines resistance can be supported by surveillance data at national aggregation levels. The data obtained from the European Surveillance of Antimicrobial Consumption and the European Antimicrobial Resistance Surveillance System suggest that variation of consumption coincides with the occurrence of resistance at the country level. Linear regression analysis showed that the association between antimicrobial drug use and resistance was specific and robust for 2 of 3 compound pathogen combinations, stable over time, but not sensitive enough to explain all of the observed variations. Ecologic studies based on routine surveillance data indicate a relation between use and resistance and support interventions designed to reduce antimicrobial drug consumption at a national level in Europe. PMID:18976555

Antimicrobial and anticancer efficacy of antineoplastic agent capped gold nanoparticles.

PubMed

Selvaraj, V; Grace, A Nirmala; Alagar, M; Hamerton, I

2010-04-01

Synthesis of thioguanine (TG)-capped Au nanoparticles (Au@TG) and their enhanced in vitro antimicrobial and anticancer efficacy against Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, E. coli, Aspergillus fumigatus, Aspergillus niger and Hep2 cancer cell (Human epidermiod cell) have been reported. The nature of binding between 6-TG and the gold nanoparticles via complexation is investigated using ultraviolet-visible spectrum, cyclic voltammetry, transmission electron microscopy, fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The present experimental studies suggests that Au@TG are more potential than TG towards antimicrobial and anticancer activities. Hence, gold nanoparticles have the potential to be used as effective carriers for anticancer drug.

Cyclodextrins: A Weapon in the Fight Against Antimicrobial Resistance

NASA Astrophysics Data System (ADS)

Wong, Chew Ee; Dolzhenko, Anton V.; Lee, Sui Mae; Young, David James

Antimicrobial resistance poses one of the most serious global challenges of our age. Cyclodextrins (CDs) are widely utilized excipients in formulations because of their solubilizing properties, low toxicity, and low inflammatory response. This review summarizes recent investigations of antimicrobial agents involving CDs and CD-based antimicrobial materials. CDs have been employed for antimicrobial applications either through formation of inclusion complexes or by chemical modification of their hydroxyl groups to tailor pharmaceutically active compounds. Applications of these CD inclusion complexes include drug delivery, antimicrobial coatings on materials (e.g., biomedical devices and implants) and antimicrobial dressings that help to prevent wound infections. There are relatively limited studies of chemically modified CDs with antimicrobial activity. The mechanism of action of antimicrobial CD inclusion complexes and derivatives needs further elucidation, but activity of CDs and their derivatives is often associated with their interaction with bacterial cell membranes.

Aspirin inhibits the growth of Helicobacter pylori and enhances its susceptibility to antimicrobial agents

PubMed Central

Wang, W H; Wong, W M; Dailidiene, D; Berg, D E; Gu, Q; Lai, K C; Lam, S K; Wong, B C Y

2003-01-01

Background and aim: The role of Helicobacter pylori and aspirin in peptic ulcer formation and recurrence remains an important clinical topic. The interaction between aspirin and H pylori in vitro is also not clear. We investigated the effect of aspirin on the growth of H pylori and on the susceptibility of H pylori to antimicrobials. Methods: Time killing studies of H pylori were performed with different concentrations of aspirin and salicylate. Growth of bacteria was assessed spectrophotometrically and by viable colony count. The effects of aspirin on the efficiency of colony formation and on metronidazole induced mutation to rifampicin resistance in H pylori were determined. Minimal inhibitory concentrations (MICs) of aspirin and metronidazole were tested by the standard agar dilution method. MICs of amoxycillin and clarithromycin were determined by the E test method. Results: Aspirin and salicylate inhibited the growth of H pylori in a dose dependent manner and bactericidal activity was due to cell lysis. Aspirin 400 μg/ml caused a 2 logs decrease in colony forming units/ml at 48 hours, and suppressed the normal ability of metronidazole to induce new mutations to rifampicin. The IC90 of aspirin was 512 μg/ml. Increased susceptibility of amoxycillin, clarithromycin, and metronidazole to H pylori was observed at 1 mM (180 μg/ml) aspirin. Conclusions: Aspirin inhibited the growth of H pylori, suppressed the mutagenic effect of metronidazole, and enhanced the susceptibility of H pylori to antimicrobial agents. This mechanism is important in future drug development for effective clearing and overcoming resistance. PMID:12631656

Role of C-terminal heptapeptide in pore-forming activity of antimicrobial agent, gaegurin 4.

PubMed

Kim, H J; Kim, S S; Lee, M H; Lee, B J; Ryu, P D

2004-10-01

Gaegurin 4 (GGN4) is an antimicrobial peptide of 37 amino acids isolated from the skin of a frog, Rana rugosa. GGN4 has a disulfide bond between the residues 31 and 37, which is highly conserved among the antimicrobial peptides isolated from skin of the genus, Rana. However, the role of this C-terminal heptapeptide motif is not well understood. In this work, we compared the membrane effects of the full-length GGN4 (C37) and GGN4 1-30 (C30), which is devoid of the C-terminal seven amino acids to elucidate the function of the C-terminal motif. C37 induced significantly larger membrane conductance (>10x) in the model lipid bilayers formed with acidic and neutral phospholipids and larger K+ efflux from gram-positive (>30x) and gram-negative bacteria. However, the pores induced by C37 and C30 were not different in their permeability to K+ over Cl- (permeability ratio of K+ to Cl- = 4.8-7.1). In addition, the pore-forming effect of C37 or C30 in acidic membranes was not different from that in neutral membranes. Furthermore, C37-induced K+ efflux was not significantly decreased by the reducing agent, dithiothreitol. The results indicate that C-terminal heptapeptide sequence plays an important role in maintaining the high pore-forming activity of GGN4, but does not participate in forming GGN4-induced pore structure. The disulfide bond in this region does not appear critical for such high ionophoric activity of GGN4.

New Approaches to Antibiotic Use and Review of Recently Approved Antimicrobial Agents.

PubMed

Hahn, Andrew W; Jain, Rupali; Spach, David H

2016-07-01

Antimicrobial drug-resistance continues to force adaptation in our clinical practice. We explore new evidence regarding adjunctive antibiotic therapy for skin and soft tissue abscesses as well as duration of therapy for intra-abdominal abscesses. As new evidence refines optimal practice, it is essential to support clinicians in adopting practice patterns concordant with evidence-based guidelines. We review a simple approach that can 'nudge' clinicians towards concordant practices. Finally, the use of novel antimicrobials will play an increasingly important role in contemporary therapy. We review five new antimicrobials recently FDA-approved for use in drug-resistant infections: dalbavancin, oritavancin, ceftaroline, ceftolozane-tazobactam, and ceftazidime-avibactam. Copyright © 2016 Elsevier Inc. All rights reserved.

Durability of Anti-Infective Effect of Long-Term Silicone Sheath Catheters Impregnated with Antimicrobial Agents

PubMed Central

Tcholakian, Robert K.; Raad, Issam I.

2001-01-01

This study was performed to test the long-term antimicrobial efficacy of impregnated silicone catheters comprising an antimicrobial layer sandwiched between an external surface sheath and a luminal surface silicone sheath. The design of the catheter permits the introduction of various antimicrobials in addition to anticoagulants or antifibrins in the antimicrobial layer and allows their gradual release over a period of months after insertion. The in vitro data presented show that the catheter can provide antimicrobial activity for 90 days, after being replated for 15 7-day cycles of replating. When the catheters were immersed in human serum and incubated at 37°C, they demonstrated significant antimicrobial activity after more than 325 days of incubation. The significant long-term in vitro antimicrobial activity observed may imply effective in vivo activity for almost 1 year after insertion and could serve as a cost-effective alternative to surgically implantable silicone catheters. PMID:11408213

Antimicrobial susceptibility pattern of clinical isolates of Burkholderia pseudomallei in Bangladesh.

PubMed

Dutta, Subarna; Haq, Sabah; Hasan, Mohammad Rokibul; Haq, Jalaluddin Ashraful

2017-07-20

Melioidosis an infectious disease, caused by a Gram negative bacterium called Burkholderia pseudomallei, is endemic in Bangladesh. This organism is sensitive to limited number of antimicrobial agents and need prolonged treatment. There is no comprehensive data on the antimicrobial susceptibility profile of B. pseudomallei isolated in Bangladesh over last several years. The present study aimed to determine the antimicrobial susceptibility pattern of B. pseudomallei isolated in a tertiary care hospital of Dhaka city from 2009 to 2015. All B. pseudomallei isolated from melioidosis patients over a period of 7 years (2009-2015) in the Department of Microbiology of a 725-bed tertiary care referral hospital in Dhaka city, Bangladesh were included in the study. B. pseudomallei was identified by Gram stain, culture, specific biochemical tests, serology and PCR using specific primers constructed from 16s rRNA region of B. pseudomallei. Antimicrobial susceptibility to specific agents was determined by disk diffusion and minimum inhibitory concentration methods. A total of 20 isolates of B. pseudomallei which were isolated from patients coming from different geographic locations of Bangladesh were included in the study. All the isolates were uniformly sensitive (100%) to ceftazidime, imipenem, piperacillin-tazobactam, amoxicillin-clavulanic acid and tetracycline by both disk diffusion and MIC methods. Two strains were resistant to trimethoprim-sulfamethoxazole by disk diffusion method but were sensitive by MIC method. The MIC 50 and MIC 90 values of the above antimicrobial agents were almost similar. All the isolates were resistant to amikacin by both MIC and disk diffusion methods. The results of the study suggest that B. pseudomallei prevalent in Bangladesh were still susceptible to all recommended antimicrobial agents used for the treatment of melioidosis. However, regular monitoring is needed to detect any emergence of resistance and shifting of MIC 50 and MIC 90 values.

Contact Active Antimicrobial Coatings Prepared by Polymer Blending.

PubMed

Cuervo-Rodríguez, Rocío; López-Fabal, Fátima; Gómez-Garcés, José L; Muñoz-Bonilla, Alexandra; Fernández-García, Marta

2017-11-01

Herein, contact active antimicrobial films are prepared by simply blending cationic amphiphilic block copolymers with commercial polystyrene (PS). The copolymers are prepared by combining atom transfer radical polymerization and "click chemistry." A variety of copolymers are synthesized, and composed of a PS segment and an antimicrobial block bearing flexible side chain with thiazole and triazole groups, 4-(1-(2-(4-methylthiazol-5-yl)ethyl)-1H-1,2,3-triazol-4-yl) butyl methacrylate (TTBM). The length of the TTBM block is varied as well as the alkylating agent. Different films are prepared from N,N-dimethylformamide solution, containing variable PS-b-PTTBM/PS ratio: from 0 to 100 wt%. Remarkably, the blend films, especially those with 30 and 50 wt% of copolymers, exhibit excellent antimicrobial activities against Gram-positive, Gram-negative bacteria and fungi, even higher than films prepared exclusively from the cationic copolymers. Blends composed of 50 wt% of the copolymers present a more than 99.999% killing efficiency against the studied microorganisms. The better activity found in blends can be due to the higher roughness, which increases the surface area and consequently the contact with the microorganisms. These results demonstrate that the use of blends implies a reduction of the content of antimicrobial agent and also enhances the antimicrobial activity, providing new insights for the better designing of antimicrobial coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antimicrobial property and microstructure of micro-emulsion edible composite films against Listeria.

PubMed

Guo, Mingming; Jin, Tony Z; Yadav, Madhav P; Yang, Ruijin

2015-09-02

Edible antimicrobial composite films from micro-emulsions containing all natural compounds were developed and their antimicrobial properties and microstructures were investigated. Chitosan, allyl isothiocyanate (AIT), barley straw arabinoxylan (BSAX), and organic acids (acetic, lactic and levulinic acids) were used as film-forming agent, antimicrobial agent, emulsifier, and solvent, respectively. Micro-emulsions were obtained using high pressure homogenization (HPH) processing at 138MPa for 3cycles. The composite films made from the micro-emulsions significantly (p<0.05) inactivated Listeria innocua in tryptic soy broth (TSB) and on the surface of ready-to-eat (RTE) meat samples, achieving microbial reductions of over 4logCFU/ml in TSB after 2days at 22°C and on meat samples after 35days at 10°C. AIT was a major contributor to the antimicrobial property of the films and HPH processing further enhanced its antimicrobial efficacy, while the increase of chitosan from 1.5% to 3%, or addition of acetic acid to the formulations didn't result in additional antimicrobial effects. This study demonstrated an effective approach to developing new edible antimicrobial films and coatings used for food applications. Published by Elsevier B.V.

Novel Treatment of Staphylococcus aureus Device-Related Infections Using Fibrinolytic Agents.

PubMed

Hogan, S; O'Gara, J P; O'Neill, E

2018-02-01

Staphylococcal infections involving biofilms represent a significant challenge in the treatment of patients with device-related infections. Staphylococcus aureus biofilms have been shown to be SaeRS regulated and dependent on the coagulase-catalyzed conversion of fibrinogen into fibrin on surfaces coated with human plasma. Here we investigated the treatment of staphylococcal biofilm device-related infections by digesting the fibrin biofilm matrix with and without existing antimicrobials. The fibrinolytic agents plasmin, streptokinase, and nattokinase, and TrypLE, a recombinant trypsin-like protease, were used to digest and treat S. aureus biofilms grown in vitro using in vivo -like static biofilm assays with and without antimicrobials. Cytotoxicity, the potential to induce a cytokine response in whole human blood, and the risk of induction of tolerance to fibrinolytic agents were investigated. A rat model of intravascular catheter infection was established to investigate the efficacy of selected fibrinolytic agents in vivo Under biomimetic conditions, the fibrinolytic agents effectively dispersed established S. aureus biofilms and, in combination with common antistaphylococcal antimicrobials, effectively killed bacterial cells being released from the biofilm. These fibrinolytic agents were not cytotoxic and did not affect the host immune response. The rat model of infection successfully demonstrated the activity of the selected fibrinolytic agents alone and in combination with antimicrobials on established biofilms in vivo TrypLE and nattokinase most successfully removed adherent cells from plasma-coated surfaces and significantly improved the efficacy of existing antimicrobials against S. aureus biofilms in vitro and in vivo These biofilm dispersal agents represent a viable future treatment option for S. aureus device-related infections. Copyright © 2018 American Society for Microbiology.

The Global Challenge of Antimicrobial Resistance: Insights from Economic Analysis

PubMed Central

Eggleston, Karen; Zhang, Ruifang; Zeckhauser, Richard J.

2010-01-01

The prevalence of antimicrobial resistance (AR) limits the therapeutic options for treatment of infections, and increases the social benefit from disease prevention. Like an environmental resource, antimicrobials require stewardship. The effectiveness of an antimicrobial agent is a global public good. We argue for greater use of economic analysis as an input to policy discussion about AR, including for understanding the incentives underlying health behaviors that spawn AR, and to supplement other methods of tracing the evolution of AR internationally. We also discuss integrating antimicrobial stewardship into global health governance. PMID:20948953

Antimicrobial Substances for Food Packaging Products: The Current Situation.

PubMed

Pellerito, Alessandra; Ameen, Sara M; Micali, Maria; Caruso, Giorgia

2018-04-04

Antimicrobial substances are widely used in many anthropic activities, including sanitary and military services for the human population. These compounds are also known to be used in food production, agricultural activities, and partially correlated industrial sectors. However, there are concerns regarding the link between the abuse of antimicrobial agents in these ambits and the possible detection of antibiotic-resistant microorganisms. Modern food and beverage products are generally found on the market as prepackaged units, with several exceptions. Consequently, positive and negative features of a specific food or beverage should be considered as the result of the synergic action of different components, including the container (or the assembled sum of packaging materials). At present, the meaning of food container also includes the creation and development of new packaging materials that are potentially able to interact with the contained food. "Active" packaging systems can be realized with antimicrobial substances. On the other hand, a careful evaluation of risks and advantages correlated with antimicrobial agents is needed because of possible negative and/or unexpected failures.

High CO2 concentration as an inductor agent to drive production of recombinant phytotoxic antimicrobial peptides in plant biofactories.

PubMed

Ruiz, Cristina; Pla, Maria; Company, Nuri; Riudavets, Jordi; Nadal, Anna

2016-03-01

Cationic α-helical antimicrobial peptides such as BP100 are of increasing interest for developing novel phytosanitary or therapeutic agents and products with industrial applications. Biotechnological production of these peptides in plants can be severely impaired due to the toxicity exerted on the host by high-level expression. This can be overcome by using inducible promoters with extremely low activity throughout plant development, although the yields are limited. We examined the use of modified atmospheres using the increased levels of [CO2], commonly used in the food industry, as the inductor agent to biotechnologically produce phytotoxic compounds with higher yields. Here we show that 30% [CO2] triggered a profound transcriptional response in rice leaves, including a change in the energy provision from photosynthesis to glycolysis, and the activation of stress defense mechanisms. Five genes with central roles in up-regulated pathways were initially selected and their promoters successfully used to drive the expression of phytotoxic BP100 in genetically modified (GM) rice. GM plants had a normal phenotype on development and seed production in non-induction conditions. Treatment with 30 % [CO2] led to recombinant peptide accumulation of up to 1 % total soluble protein when the Os.hb2 promoter was used. This is within the range of biotechnological production of other peptides in plants. Using BP100 as a proof-of-concept we demonstrate that very high [CO2] can be considered an economically viable strategy to drive production of recombinant phytotoxic antimicrobial peptides in plant biofactories.

Construction of Zinc Oxide into Different Morphological Structures to Be Utilized as Antimicrobial Agent against Multidrug Resistant Bacteria

PubMed Central

Elkady, M. F.; Shokry Hassan, H.; Hafez, Elsayed E.; Fouad, Ahmed

2015-01-01

Nano-ZnO has been successfully implemented in particles, rods, and tubes nanostructures via sol-gel and hydrothermal techniques. The variation of the different preparation parameters such as reaction temperature, time, and stabilizer agents was optimized to attain different morphological structures. The influence of the microwave annealing process on ZnO crystallinity, surface area, and morphological structure was monitored using XRD, BET, and SEM techniques, respectively. The antimicrobial activity of zinc oxide produced in nanotubes structure was examined against four different multidrug resistant bacteria: Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) strains. The activity of produced nano-ZnO was determined by disc diffusion technique and the results revealed that ZnO nanotubes recorded high activity against the studied strains due to their high surface area equivalent to 17.8 m2/g. The minimum inhibitory concentration (MIC) of ZnO nanotubes showed that the low concentrations of ZnO nanotubes could be a substitution for the commercial antibiotics when approached in suitable formula. Although the annealing process of ZnO improves the degree of material crystallinity, however, it declines its surface area and consequently its antimicrobial activity. PMID:26451136

Chimeric Peptides as Implant Functionalization Agents for Titanium Alloy Implants with Antimicrobial Properties

NASA Astrophysics Data System (ADS)

Yucesoy, Deniz T.; Hnilova, Marketa; Boone, Kyle; Arnold, Paul M.; Snead, Malcolm L.; Tamerler, Candan

2015-04-01

Implant-associated infections can have severe effects on the longevity of implant devices and they also represent a major cause of implant failures. Treating these infections associated with implants by antibiotics is not always an effective strategy due to poor penetration rates of antibiotics into biofilms. Additionally, emerging antibiotic resistance poses serious concerns. There is an urge to develop effective antibacterial surfaces that prevent bacterial adhesion and proliferation. A novel class of bacterial therapeutic agents, known as antimicrobial peptides (AMPs), are receiving increasing attention as an unconventional option to treat septic infection, partly due to their capacity to stimulate innate immune responses and for the difficulty of microorganisms to develop resistance towards them. While host and bacterial cells compete in determining the ultimate fate of the implant, functionalization of implant surfaces with AMPs can shift the balance and prevent implant infections. In the present study, we developed a novel chimeric peptide to functionalize the implant material surface. The chimeric peptide simultaneously presents two functionalities, with one domain binding to a titanium alloy implant surface through a titanium-binding domain while the other domain displays an antimicrobial property. This approach gains strength through control over the bio-material interfaces, a property built upon molecular recognition and self-assembly through a titanium alloy binding domain in the chimeric peptide. The efficiency of chimeric peptide both in-solution and absorbed onto titanium alloy surface was evaluated in vitro against three common human host infectious bacteria, Streptococcus mutans, Staphylococcus epidermidis, and Escherichia coli. In biological interactions such as occur on implants, it is the surface and the interface that dictate the ultimate outcome. Controlling the implant surface by creating an interface composed chimeric peptides may therefore

Effects of different surface modifying agents on the cytotoxic and antimicrobial properties of ZnO nanoparticles.

PubMed

Esparza-González, S C; Sánchez-Valdés, S; Ramírez-Barrón, S N; Loera-Arias, M J; Bernal, J; Meléndez-Ortiz, H Iván; Betancourt-Galindo, R

2016-12-01

Zinc oxide (ZnO) nanoparticles (NPs) have received considerable attention in the medical field because of their antibacterial properties, primarily for killing and reducing the activity of numerous microorganisms. The purpose of this study was to determine whether surface-modified ZnO NPs exhibit different properties compared with unmodified ZnO. The antimicrobial and cytotoxic properties of modified ZnO NPs as well as their effects on inflammatory cytokine production were evaluated. ZnO NPs were prepared using a wet chemical method. Then, the surfaces of these NPs were modified using 3-aminopropyltriethoxysilane (APTES) and dimethyl sulfoxide (DMSO) as modifying agents via a chemical hydrolysis method. According to infrared spectroscopy analysis (FTIR), the structure of the ZnO remained unchanged after modification. Antibacterial assays demonstrated that APTES modification is more effective at inducing an antimicrobial effect against Gram-negative bacteria than against Gram-positive bacteria. Cytotoxicity studies showed that cell viability was dose-dependent; moreover, pristine and APTES-modified ZnO exhibited low cytotoxicity, whereas DMSO-modified ZnO exhibited toxicity even at a low NP concentration. An investigation of inflammatory cytokine production demonstrated that the extent of stimulation was related to the ZnO NP concentration but not to the surface modification, except for IFN-γ and IL-10, which were not detected even at high NP concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

Food-grade antimicrobials potentiate the antibacterial activity of 1,2-hexanediol.

PubMed

Yogiara; Hwang, S J; Park, S; Hwang, J-K; Pan, J-G

2015-05-01

Preservative agents determining the shelf life of cosmetic products must have effective antimicrobial activity while meeting safety requirements for topical use. In this study, we determined the antimicrobial activity of 1,2-hexanediol against several Gram-positive and Gram-negative bacteria. Antimicrobial susceptibility tests have shown that 1,2-hexanediol exhibits broad-spectrum activity against Gram-positive and Gram-negative bacteria with MICs of 0·5-2% (v/v). The bactericidal concentration of 1,2-hexanediol was ranging from 1 to 2 × MIC as demonstrated by time-kill curve assay. A membrane depolarization assay showed that 1,2-hexanediol disrupted the cytoplasmic membrane potential. A checkerboard assay indicated that the effective concentration of 1,2-hexanediol was reduced up to 0·25-0·5 × MIC when combined with macelignan and octyl gallate against Gram-positive bacteria. However, this combination was not effective against Gram-negative bacteria. A turbidity reduction assay demonstrated that the combination of a high concentration of 1,2-hexanediol with food-grade antimicrobial compounds could trigger lytic activity towards Bacillus cereus cells. The remaining cell turbidity was 24·6 and 22·2% when 2% of 1,2-hexanediol was combined with 8 mg l(-1) octyl gallate or with 32 mg l(-1) macelignan respectively. This study showed that food-grade antimicrobial compounds may be used in combination with 1,2-hexanediol to increase its efficacy as a preservative agent in cosmetics. The antimicrobial activity of 1,2-hexanediol against Gram-positive and Gram-negative bacteria was potentiated with food-grade antimicrobials including xanthorrhizol, macelignan, panduratin A and octyl gallate, which have already been reported to display anti-inflammatory and other beneficial activities related to cosmetics. Therefore, the combination of 1,2-hexanediol and these food-grade antimicrobial agents would have benefits not only for increasing the antimicrobial activity

Antimicrobial Properties of Natural Phenols and Related Compounds

PubMed Central

Jurd, L.; King, A. D.; Mihara, K.; Stanley, W. L.

1971-01-01

Obtusastyrene (4-cinnamylphenol) displays effective antimicrobial activity in vitro against a variety of gram-positive bacteria, yeasts, and molds. The activity of obtusastyrene is not appreciably affected by pH, and its minimal inhibitory concentrations, 12 to 25 μg/ml for bacteria and 12 to 100 μg/ml for fungi, compare favorably with those of a number of synthetic, phenolic antimicrobial agents. PMID:5553287

Remote Antimicrobial Stewardship in Community Hospitals

PubMed Central

Wood, Zachary H.; Nicolsen, Nicole C.; Allen, Nichole; Cook, Paul P.

2015-01-01

Antimicrobial stewardship has become standard practice at university medical centers, but the practice is more difficult to implement in remote community hospitals that lack infectious diseases trained practitioners. Starting in 2011, six community hospitals within the Vidant Health system began an antimicrobial stewardship program utilizing pharmacists who reviewed charts remotely from Vidant Medical Center. Pharmacists made recommendations within the electronic medical record (EMR) to streamline, discontinue, or switch antimicrobial agents. Totals of charts reviewed, recommendations made, recommendations accepted, and categories of intervention were recorded. Linear regression was utilized to measure changes in antimicrobial use over time. For the four larger hospitals, recommendations for changes were made in an average of 45 charts per month per hospital and physician acceptance of the pharmacists’ recommendations varied between 83% and 88%. There was no significant decrease in total antimicrobial use, but much of the use was outside of the stewardship program’s review. Quinolone use decreased by more than 50% in two of the four larger hospitals. Remote antimicrobial stewardship utilizing an EMR is feasible in community hospitals and is generally received favorably by physicians. As more community hospitals adopt EMRs, there is an opportunity to expand antimicrobial stewardship beyond the academic medical center. PMID:27025642

Antimicrobial Activities and Time-Kill Kinetics of Extracts of Selected Ghanaian Mushrooms

PubMed Central

Appiah, Theresa; Boakye, Yaw Duah

2017-01-01

The rapid rise of antimicrobial resistance is a worldwide problem. This has necessitated the need to search for new antimicrobial agents. Mushrooms are rich sources of potential antimicrobial agents. This study investigated the antimicrobial properties of methanol extracts of Trametes gibbosa, Trametes elegans, Schizophyllum commune, and Volvariella volvacea. Agar well diffusion, broth microdilution, and time-kill kinetic assays were used to determine the antimicrobial activity of the extracts against selected test organisms. Preliminary mycochemical screening revealed the presence of tannins, flavonoids, triterpenoids, anthraquinones, and alkaloids in the extracts. Methanol extracts of T. gibbosa, T. elegans, S. commune, and V. volvacea showed mean zone of growth inhibition of 10.00 ± 0.0 to 21.50 ± 0.84, 10.00 ± 0.0 to 22.00 ± 1.10, 9.00 ± 0.63 to 21.83 ± 1.17, and 12.00 ± 0.0 to 21.17 ± 1.00 mm, respectively. The minimum inhibitory concentration of methanol extracts of T. gibbosa, T. elegans, S. commune, and V. volvacea ranged from 4.0 to 20, 6.0 to 30.0, 8.0 to 10.0, and 6.0 to 20.0 mg/mL, respectively. Time-kill kinetics studies showed that the extracts possess bacteriostatic action. Methanol extracts of T. gibbosa, T. elegans, S. commune, and V. volvacea exhibited antimicrobial activity and may contain bioactive compounds which may serve as potential antibacterial and antifungal agents. PMID:29234399

Novel Synthetic Antimicrobial Peptides against Streptococcus mutans▿

PubMed Central

He, Jian; Eckert, Randal; Pharm, Thanh; Simanian, Maurice D.; Hu, Chuhong; Yarbrough, Daniel K.; Qi, Fengxia; Anderson, Maxwell H.; Shi, Wenyuan

2007-01-01

Streptococcus mutans, a common oral pathogen and the causative agent of dental caries, has persisted and even thrived on the tooth surface despite constant removal and eradication efforts. In this study, we generated a number of synthetic antimicrobial peptides against this bacterium via construction and screening of several structurally diverse peptide libraries where the hydrophobicity and charge within each library was varied incrementally in order to generate a collection of peptides with different biochemical characteristics. From these libraries, we identified multiple peptides with robust killing activity against S. mutans. To further improve their effectiveness, the most bactericidal peptides from each library were synthesized together as one molecule, in various combinations, with and without a flexible peptide linker between each antimicrobial region. Many of these “fusion” peptides had enhanced killing activities in comparison with those of the original nonconjoined molecules. The results presented here illustrate that small libraries of biochemically constrained peptides can be used to generate antimicrobial peptides against S. mutans, several of which may be likely candidates for the development of anticaries agents. PMID:17296741

Antimicrobial-Coated Granules for Disinfecting Water

NASA Technical Reports Server (NTRS)

Akse, James R.; Holtsnider, John T.; Kliestik, Helen

2011-01-01

Methods of preparing antimicrobialcoated granules for disinfecting flowing potable water have been developed. Like the methods reported in the immediately preceding article, these methods involve chemical preparation of substrate surfaces (in this case, the surfaces of granules) to enable attachment of antimicrobial molecules to the surfaces via covalent bonds. A variety of granular materials have been coated with a variety of antimicrobial agents that include antibiotics, bacteriocins, enzymes, bactericides, and fungicides. When employed in packed beds in flowing water, these antimicrobial-coated granules have been proven effective against gram-positive bacteria, gram-negative bacteria, fungi, and viruses. Composite beds, consisting of multiple layers containing different granular antimicrobial media, have proven particularly effective against a broad spectrum of microorganisms. These media have also proven effective in enhancing or potentiating the biocidal effects of in-line iodinated resins and of very low levels of dissolved elemental iodine.

[Susceptibilities of Escherichia coli, Salmonella and Staphylococcus aureus isolated from animals to ofloxacin and commonly used antimicrobial agents].

PubMed

Takahashi, I; Yoshida, T; Higashide, Y; Sakano, T

1990-01-01

Susceptibilities of Escherichia coli, Salmonella and Staphylococcus aureus isolated from chickens, pigs and cattle to ofloxacin (OFLX) and commonly used antimicrobial agents were investigated. 1. E. coli (28 isolates) demonstrated the highest level of susceptibility of OFLX (MIC 0.10-0.39 micrograms/ml for all the isolates) among all the test drugs. Commonly used antimicrobial agents to which these isolates responded with relatively high susceptibilities (MIC50 0.78-6.25 micrograms/ml) included oxolinic acid (OXA), ampicillin (ABPC), kanamycin (KM) and chloramphenicol (CP) with their MIC50 values in the increasing order as above. Drugs to which these isolates responded with moderate to weak susceptibilities (MIC50 25 approximately greater than 800 micrograms/ml) were doxycycline (DOXY), streptomycin (SM), spectinomycin (SPCM) and sulfadimethoxine (SDMX) in the increasing order of MIC50. E. coli isolates with resistances to all the test drugs other than OFLX and OXA amounted to 7.1-57.1% of the isolates examined and 20 isolates (71.4%) in total. 2. Susceptibilities to OFLX and 4 existing pyridonecarboxylic acid derivatives of E. coli (48 samples) isolated recently from diarrheal pigs were compared. When evaluated in terms of MIC50, the values of OFLX and norfloxacin were both 0.10 micrograms/ml. The values increased by differences of 0.39-3.13 micrograms/ml in an order of OXA, pipemidic acid and nalidixic acid. 3. Salmonella (28 isolates) demonstrated the highest level of susceptibility to OFLX (MIC 0.20-0.39 micrograms/ml for all the isolates) among all the test drugs. The drugs to which these isolates responded with relatively high to moderate susceptibilities (MIC50 0.78-12.5 micrograms/ml) included ABPC, OXA, DOXY, KM, CP and SM with their MIC50 values increasing in this order. The drugs to which the isolates responded with low susceptibilities (MIC50 above 100 micrograms/ml) were SPCM and SDMX. Of all the 28 Salmonella isolates tested, 7.1-32.1% were resistant

Antimicrobial resistance trends among Escherichia coli isolates obtained from dairy cattle in the northeastern United States, 2004-2011.

PubMed

Cummings, Kevin J; Aprea, Victor A; Altier, Craig

2014-01-01

Monitoring antimicrobial resistance trends among bacteria isolated from food animals and people is necessary to inform risk analyses and guide public policy regarding antimicrobial use. Our objectives were to describe the antimicrobial resistance status of Escherichia coli isolates from dairy cattle in the northeastern United States and to identify trends in resistance to selected antimicrobial agents over time. We collected data retrospectively for all bovine E. coli isolates that were obtained from samples submitted to Cornell University's Animal Health Diagnostic Center between January 1, 2004 and December 31, 2011. We investigated temporal trends in the prevalence of resistant E. coli for each antimicrobial agent using the Cochran-Armitage trend test. Antimicrobial susceptibility testing was performed on 3373 bovine E. coli isolates from clinical samples submitted during the study period. Overall resistance to each antimicrobial agent ranged from 2.7% (enrofloxacin) to 91.3% (oxytetracycline). There was evidence of a significantly decreasing trend in prevalence of resistance to several agents: chlortetracycline, florfenicol, neomycin, oxytetracycline, spectinomycin, and trimethoprim/sulfamethoxazole. However, a significantly increasing trend in prevalence of resistance to enrofloxacin was also evident. These results do not support the idea that current antimicrobial use practices on dairy operations are driving a general increase in the emergence and dissemination of drug-resistant E. coli in the region served by the laboratory. However, resistance to some drugs remained consistently high during the study period, and increasing resistance to enrofloxacin is a key area of concern.

Evaluation of antimicrobial peptides as novel bactericidal agents for room temperature-stored platelets.

PubMed

Mohan, Ketha V K; Rao, Shilpakala Sainath; Atreya, Chintamani D

2010-01-01

A single cost-effective pathogen inactivation approach would help to improve the safety of our nation's blood supply. Several methods and technologies are currently being studied to help reduce bacterial contamination of blood components. There is clearly need for simple and easy-to-use pathogen inactivation techniques specific to plasma, platelets (PLTs), and red blood cells. In this report, we introduce a novel proof of concept: using known therapeutic antimicrobial peptides (AMPs) as bactericidal agents for room temperature-stored PLT concentrates (PCs). Nine synthetic AMPs, four from PLT microbicidal protein-derived peptides (PD1-4) and five Arg-Trp (RW) repeat peptides containing one to five repeats, were tested for bactericidal activity in plasma and PC samples spiked with Staphylococcus aureus, S. epidermidis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Bacillus cereus. A 3-log reduction of viable bacteria was considered as the bactericidal activity of a given peptide. In both plasma alone and PCs, RW3 peptide demonstrated bactericidal activity against S. aureus, S. epidermidis, E. coli, P. aeruginosa, and K. pneumoniae; PD4 and RW2 against P. aeruginosa; and RW4 against K. pneumoniae. The activity of each of these four peptides against the remaining bacterial species in the test panel resulted in less than a 3-log reduction in the number of viable bacteria and hence considered ineffective. These findings suggest a new approach to improving the safety of blood components, demonstrating the potential usefulness of screening therapeutic AMPs against selected bacteria to identify suitable bactericidal agents for stored plasma, PCs, and other blood products.

Multifactorial antimicrobial wood protectants

Treesearch

Robert D. Coleman; Carol A. Clausen

2008-01-01

It is unlikely that a single antimicrobial compound, whether synthetic or natural, will provide the ‘magic bullet’ for eliminating multiple biological agents affecting wood products. Development of synergistic combinations of selected compounds, especially those derived from natural sources, is recognized as a promising approach to improved wood protection. Recent...

Novel 4-Thiazolidinone Derivatives as Anti-Infective Agents: Synthesis, Characterization, and Antimicrobial Evaluation.

PubMed

Gupta, Amit; Singh, Rajendra; Sonar, Pankaj K; Saraf, Shailendra K

2016-01-01

A series of new 4-thiazolidinone derivatives was synthesized, characterized by spectral techniques, and screened for antimicrobial activity. All the compounds were evaluated against five Gram-positive bacteria, two Gram-negative bacteria, and two fungi, at concentrations of 50, 100, 200, 400, 800, and 1600 µg/mL, respectively. Minimum inhibitory concentrations of all the compounds were also determined and were found to be in the range of 100-400 µg/mL. All the compounds showed moderate-to-good antimicrobial activity. Compounds 4a [2-(4-fluoro-phenyl)-3-(4-methyl-5,6,7,8-tetrahydro-quinazolin-2-yl)-thiazolidin-4-one] and 4e [3-(4,6-dimethyl-pyrimidin-2-yl)-2-(2-methoxy-phenyl)-thiazolidin-4-one] were the most potent compounds of the series, exhibiting marked antimicrobial activity against Pseudomonas fluorescens, Staphylococcus aureus, and the fungal strains. Thus, on the basis of results obtained, it may be concluded that synthesized compounds exhibit a broad spectrum of antimicrobial activity.

Optimized dispersion of ZnO nanoparticles and antimicrobial activity against foodborne pathogens and spoilage microorganisms

NASA Astrophysics Data System (ADS)

Espitia, Paula Judith Perez; Soares, Nilda de Fátima Ferreira; Teófilo, Reinaldo F.; Vitor, Débora M.; Coimbra, Jane Sélia dos Reis; de Andrade, Nélio José; de Sousa, Frederico B.; Sinisterra, Rubén D.; Medeiros, Eber Antonio Alves

2013-01-01

Single primary nanoparticles of zinc oxide (nanoZnO) tend to form particle collectives, resulting in loss of antimicrobial activity. This work studied the effects of probe sonication conditions: power, time, and the presence of a dispersing agent (Na4P2O7), on the size of nanoZnO particles. NanoZnO dispersion was optimized by response surface methodology (RSM) and characterized by the zeta potential (ZP) technique. NanoZnO antimicrobial activity was investigated at different concentrations (1, 5, and 10 % w/w) against four foodborne pathogens and four spoilage microorganisms. The presence of the dispersing agent had a significant effect on the size of dispersed nanoZnO. Minimum size after sonication was 238 nm. An optimal dispersion condition was achieved at 200 W for 45 min of sonication in the presence of the dispersing agent. ZP analysis indicated that the ZnO nanoparticle surface charge was altered by the addition of the dispersing agent and changes in pH. At tested concentrations and optimal dispersion, nanoZnO had no antimicrobial activity against Pseudomonas aeruginosa, Lactobacillus plantarum, and Listeria monocytogenes. However, it did have antimicrobial activity against Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger. Based on the exhibited antimicrobial activity of optimized nanoZnO against some foodborne pathogens and spoilage microorganisms, nanoZnO is a promising antimicrobial for food preservation with potential application for incorporation in polymers intended as food-contact surfaces.

Benefits and risks of antimicrobial use in food-producing animals

PubMed Central

Hao, Haihong; Cheng, Guyue; Iqbal, Zahid; Ai, Xiaohui; Hussain, Hafiz I.; Huang, Lingli; Dai, Menghong; Wang, Yulian; Liu, Zhenli; Yuan, Zonghui

2014-01-01

Benefits and risks of antimicrobial drugs, used in food-producing animals, continue to be complex and controversial issues. This review comprehensively presents the benefits of antimicrobials drugs regarding control of animal diseases, protection of public health, enhancement of animal production, improvement of environment, and effects of the drugs on biogas production and public health associated with antimicrobial resistance. The positive and negative impacts, due to ban issue of antimicrobial agents used in food-producing animals, are also included in the discussion. As a double-edged sword, use of these drugs in food-animals persists as a great challenge. PMID:24971079

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.

Antimicrobial Peptides as Potential Alternatives to Antibiotics in Food Animal Industry.

PubMed

Wang, Shuai; Zeng, Xiangfang; Yang, Qing; Qiao, Shiyan

2016-05-03

Over the last decade, the rapid emergence of multidrug-resistant pathogens has become a global concern, which has prompted the search for alternative antibacterial agents for use in food animals. Antimicrobial peptides (AMPs), produced by bacteria, insects, amphibians and mammals, as well as by chemical synthesis, are possible candidates for the design of new antimicrobial agents because of their natural antimicrobial properties and a low propensity for development of resistance by microorganisms. This manuscript reviews the current knowledge of the basic biology of AMPs and their applications in non-ruminant nutrition. Antimicrobial peptides not only have broad-spectrum activity against bacteria, fungi, and viruses but also have the ability to bypass the common resistance mechanisms that are placing standard antibiotics in jeopardy. In addition, AMPs have beneficial effects on growth performance, nutrient digestibility, intestinal morphology and gut microbiota in pigs and broilers. Therefore, AMPs have good potential as suitable alternatives to conventional antibiotics used in swine and poultry industries.

Antimicrobial Resistance in Asia: Current Epidemiology and Clinical Implications

PubMed Central

Kang, Cheol-In

2013-01-01

Antimicrobial resistance has become one of the most serious public health concerns worldwide. Although circumstances may vary by region or country, it is clear that some Asian countries are epicenters of resistance, having seen rapid increases in the prevalence of antimicrobial resistance of major bacterial pathogens. In these locations, however, the public health infrastructure to combat this problem is very poor. The prevalence rates of methicillin-resistant Staphylococcus aureus (MRSA), macrolide-resistant Streptococcus pneumoniae, and multidrug-resistant enteric pathogens are very high due to the recent emergence of extremely drug-resistant gram-negative bacilli in Asia. Because antimicrobial options for these pathogens are extremely limited, infections caused by antimicrobial-resistant bacteria are often associated with inappropriate antimicrobial therapy and poor clinical outcomes. Physicians should be aware of the current epidemiological status of resistance and understand the appropriate use of antimicrobial agents in clinical practice. This review focuses on describing the epidemiology and clinical implications of antimicrobial-resistant bacterial infections in Asian countries. PMID:24265947

Plant nutraceuticals as antimicrobial agents in food preservation: terpenoids, polyphenols and thiols.

PubMed

Gutiérrez-Del-Río, Ignacio; Fernández, Javier; Lombó, Felipe

2018-05-16

Synthetic food additives generate a negative perception in consumers. Therefore, food manufacturers search for safer natural alternatives as those involving phytochemicals and plant essential oils. These bioactives have antimicrobial activities widely proved in in vitro tests. Foodborne diseases cause thousands of deaths and millions of infections every year, mainly due to pathogenic bacteria as Salmonella spp., Campylobacter spp., Escherichia coli, Bacillus cereus, Listeria monocytogenes or Staphylococcus aureus. This review summarizes industrially interesting antimicrobial bioactivities, as well as their mechanisms of action, for three main types of plant nutraceuticals, terpenoids (as carnosic acid), polyphenols (as quercetin) and thiols (as allicin), which are important constituents of plant essential oils with a broad range of antimicrobial effects. These phytochemicals are widely distributed in fruits and vegetables and are really useful in food preservation as they inhibit microbial growth. Copyright © 2018. Published by Elsevier B.V.

Oral administration of antimicrobials increase antimicrobial resistance in E. coli from chicken--a systematic review.

PubMed

Simoneit, C; Burow, E; Tenhagen, B-A; Käsbohrer, A

2015-01-01

Antimicrobials play an important role in animal and human health care. It was the aim of this systematic review to assess the effects of oral administration of antimicrobials on the development of antimicrobial resistance (AMR) in Escherichia coli (E. coli) from chickens. Moreover, the effects of the administration of more than one antimicrobial and of different dosages were studied. Literature was searched in November 2012 from the electronic databases ISI Web of Science, PubMed, Scopus and a national literature database (DIMDI) as well as the database ProQuest LLC. The search was updated in March 2014. Original studies describing a treatment (A) and a control group of either non-treatment (C) or initial value (0) and determining AMR in E. coli at different sample points (SP) were included. The literature search resulted in 35 full text articles on the topic, seven (20%) of which contained sufficient information on the administered antimicrobial and the impact of treatment on AMR. Most papers described the use of more than one antimicrobial, several dosages, controls (non-treatment or pre-treatment) and measured AMR at different SPs leading to a total of 227 SPs on the impact of the use of antimicrobials on AMR in chickens. 74% of the SPs (168/227) described a higher AMR-rate in E. coli from treated animals than from controls. After the administration of a single antimicrobial, AMR increased at 72% of the SPs. Administration of more than one antimicrobial increased AMR at 82% of the SPs. Higher dosages were associated with similar or higher AMR rates. The limited number of studies for each antimicrobial agent and the high variability in the resistance effect call for more well designed studies on the impact of oral administration on AMR development and spread. Copyright © 2014 Elsevier B.V. All rights reserved.

Antimicrobial resistance and genetic profiling of Escherichia coli from a commercial beef packing plant.

PubMed

Aslam, Mueen; Service, Cara

2006-07-01

The objective of this study was to investigate the extent of antimicrobial resistance and to genetically characterize resistant Escherichia coli recovered from a commercial beef packing plant. E. coli isolates were recovered by a hydrophobic grid membrane filtration method by direct plating on SD-39 medium. A total of 284 isolates comprising 71, 36, 55, 52, and 70 isolates from animal hides, washed carcasses, conveyers, beef trimmings, and ground beef, respectively, were analyzed. The susceptibility of E. coli isolates to 15 antimicrobial agents was evaluated with an automated broth microdilution system, and the genetic characterization of these isolates was performed by the random amplified polymorphic DNA (RAPD) method. Of the 284 E. coli isolates, 56% were sensitive to all 15 antimicrobial agents. Resistance to tetracycline, ampicillin, and streptomycin was observed in 38, 9, and 6% of the isolates, respectively. Resistance to one or more antimicrobial agents was observed in 51% of the E. coli isolates recovered from the hides but in only 25% of the E. coli from the washed carcasses. Resistance to one or more antimicrobial agents was observed in 49, 50, and 37% of the isolates recovered from conveyers, beef trimmings, and ground beef, respectively. The RAPD pattern data showed that the majority of resistant E. coli isolates were genetically diverse. Only a few RAPD types of resistant strains were shared among various sample sources. The results of this study suggest that antimicrobial-resistant E. coli isolates were prevalent during all stages of commercial beef processing and that considerably higher numbers of resistant E. coli were present on conveyers, beef trimmings, and ground beef than on dressed carcasses. This stresses the need for improving hygienic conditions during all stages of commercial beef processing and meatpacking to avoid the risks of transfer of antimicrobial-resistant bacteria to humans.

Antimicrobial agents are societal drugs: how should this influence prescribing?

PubMed

Sarkar, Paul; Gould, Ian M

2006-01-01

This paper is concerned with how those who prescribe antimicrobials should consider the wider repercussions of their actions. It is accepted that in an ecological system, pressure will cause evolution; this is also the case with antimicrobials, the result being the development of resistance and the therapeutic failure of drugs. To an extent, this can be ameliorated through advances by the pharmaceutical industry, but that should not stop us from critically appraising our use and modifying our behavior to slow this process down. Up to 50% of prescribing in human medicine and 80% in veterinary medicine and farming has been considered questionable. The Alliance for the Prudent Use of Antimicrobials (APUA) was approached by the WHO to review the situation. Their recommendations include decreasing the prescribing of antibacterials for nonbacterial infections. In the UK, there has been an initiative called "the path of least resistance". This encourages general practitioners to avoid prescribing or reduce the duration of prescriptions for conditions such as upper respiratory tract infections and uncomplicated urinary tract infections; this approach has been successful. Another recommendation is to reduce the prescribing of broad-spectrum antibacterials. In UK hospitals, the problems identified with the inappropriate use of antibacterials are insufficient training in infectious disease, difficulty in selecting empirical antibacterial therapy, poor use of available microbiological information, the fear of litigation and the fact that the majority of antibacterials are prescribed by the least experienced doctors. With close liaison between the laboratories and clinicians, and the development of local protocols, this can be addressed. Another recommendation is to tighten the use of antibacterial prophylaxis and to improve patient compliance. Through a combination of improved education for doctors and patients, and improved communication skills, these problems can be

Antimicrobial susceptibility profiles of gram-negative bacteria causing infections collected across India during 2014-2016: Study for monitoring antimicrobial resistance trend report.

PubMed

Veeraraghavan, Balaji; Jesudason, Mark Ranjan; Prakasah, John Antony Jude; Anandan, Shalini; Sahni, Rani Diana; Pragasam, Agila Kumari; Bakthavatchalam, Yamuna Devi; Selvakumar, Rajesh Joseph; Dhole, T N; Rodrigues, Camilla; Roy, Indranil; Joshi, Sangeetha; Chaudhuri, Bhaskar Narayan; Chitnis, D S

2018-01-01

The emergence of antibiotic resistance among bacterial pathogens in the hospital and community has increased the concern to the health-care providers due to the limited treatment options. Surveillance of antimicrobial resistance (AMR) in frequently isolated bacterial pathogens causing severe infections is of great importance. The data generated will be useful for the clinicians to decide empiric therapy on the local epidemiological resistance profile of the antimicrobial agents. This study aims to monitor the distribution of bacterial pathogen and their susceptibility pattern to the commonly used antimicrobial agents. This study includes Gram-negative bacilli collected from intra-abdominal, urinary tract and respiratory tract infections during 2014-2016. Isolates were collected from seven hospitals across India. All the study isolates were characterised up to species level, and minimum inhibitory concentration was determined for a wide range of antimicrobials included in the study panel. The test results were interpreted as per standard Clinical Laboratory Standards Institute guidelines. A total of 2731 isolates of gram-negative bacteria were tested during study period. The most frequently isolated pathogens were 44% of Escherichia coli (n = 1205) followed by 25% of Klebsiella pneumoniae (n = 676) and 11% of Pseudomonas aeruginosa (n = 308). Among the antimicrobials tested, carbapenems were the most active, followed by amikacin and piperacillin/tazobactam. The rate of extended-spectrum beta-lactamase (ESBL)-positive isolates were ranged from 66%-77% in E. coli to 61%-72% in K. pneumoniae, respectively. Overall, colistin retains its activity in > 90% of the isolates tested and appear promising. Increasing rates of ESBL producers have been noted, which is alarming. Further, carbapenem resistance was also gradually increasing, which needs much attention. Overall, this study data show that carbapenems, amikacin and colistin continue to be the best agents available to

Graphene Materials in Antimicrobial Nanomedicine: Current Status and Future Perspectives.

PubMed

Karahan, Hüseyin Enis; Wiraja, Christian; Xu, Chenjie; Wei, Jun; Wang, Yilei; Wang, Liang; Liu, Fei; Chen, Yuan

2018-03-05

Graphene materials (GMs), such as graphene, graphene oxide (GO), reduced GO (rGO), and graphene quantum dots (GQDs), are rapidly emerging as a new class of broad-spectrum antimicrobial agents. This report describes their state-of-the-art and potential future covering both fundamental aspects and biomedical applications. First, the current understanding of the antimicrobial mechanisms of GMs is illustrated, and the complex picture of underlying structure-property-activity relationships is sketched. Next, the different modes of utilization of antimicrobial GMs are explained, which include their use as colloidal dispersions, surface coatings, and photothermal/photodynamic therapy agents. Due to their practical relevance, the examples where GMs function as synergistic agents or release platforms for metal ions and/or antibiotic drugs are also discussed. Later, the applicability of GMs in the design of wound dressings, infection-protective coatings, and antibiotic-like formulations ("nanoantibiotics") is assessed. Notably, to support our assessments, the existing clinical applications of conventional carbon materials are also evaluated. Finally, the key hurdles of the field are highlighted, and several possible directions for future investigations are proposed. We hope that the roadmap provided here will encourage researchers to tackle remaining challenges toward clinical translation of promising research findings and help realize the potential of GMs in antimicrobial nanomedicine. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antimicrobial agents for preventing peritonitis in peritoneal dialysis patients.

PubMed

Campbell, Denise; Mudge, David W; Craig, Jonathan C; Johnson, David W; Tong, Allison; Strippoli, Giovanni Fm

2017-04-08

Peritoneal dialysis (PD) is an important therapy for patients with end-stage kidney disease and is used in more than 200,000 such patients globally. However, its value is often limited by the development of infections such as peritonitis and exit-site and tunnel infections. Multiple strategies have been developed to reduce the risk of peritonitis including antibiotics, topical disinfectants to the exit site and antifungal agents. However, the effectiveness of these strategies has been variable and are based on a small number of randomised controlled trials (RCTs). The optimal preventive strategies to reduce the occurrence of peritonitis remain unclear.This is an update of a Cochrane review first published in 2004. To evaluate the benefits and harms of antimicrobial strategies used to prevent peritonitis in PD patients. We searched the Cochrane Kidney and Transplant's Specialised Register to 4 October 2016 through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. RCTs or quasi-RCTs in patients receiving chronic PD, which evaluated any antimicrobial agents used systemically or locally to prevent peritonitis or exit-site/tunnel infection were included. Two authors independently assessed risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratio (RR) with 95% confidence intervals (CI). Thirty-nine studies, randomising 4435 patients, were included. Twenty additional studies have been included in this update. The risk of bias domains were often unclear or high; risk of bias was judged to be low in 19 (49%) studies for random sequence generation, 12 (31%) studies for

Antimicrobial silver: An unprecedented anion effect

PubMed Central

Swathy, J. R.; Sankar, M. Udhaya; Chaudhary, Amrita; Aigal, Sahaja; Anshup; Pradeep, T.

2014-01-01

Silver is an indispensable metal but its use has to be minimised for sustainable growth. Much of the silver lost during use is unrecoverable; an example being its use as an antimicrobial agent, a property known since ages. While developing methods to create an affordable drinking water purifier especially for the developing world, we discovered that 50 parts per billion (ppb) of Ag+ released continuously from silver nanoparticles confined in nanoscale cages is enough to cause antimicrobial activity in conditions of normal water. Here we show that the antibacterial and antiviral activities of Ag+ can be enhanced ~1,000 fold, selectively, in presence of carbonate ions whose concentration was maintained below the drinking water norms. The protective layers of the organisms were affected during the carbonate-assisted antimicrobial activity. It is estimated that ~1,300 tons of silver can be saved annually using this new way to enhance its antimicrobial activity. PMID:25418185

Plant Antimicrobial Peptides as Potential Anticancer Agents

PubMed Central

Guzmán-Rodríguez, Jaquelina Julia; López-Gómez, Rodolfo

2015-01-01

Antimicrobial peptides (AMPs) are part of the innate immune defense mechanism of many organisms and are promising candidates to treat infections caused by pathogenic bacteria to animals and humans. AMPs also display anticancer activities because of their ability to inactivate a wide range of cancer cells. Cancer remains a cause of high morbidity and mortality worldwide. Therefore, the development of methods for its control is desirable. Attractive alternatives include plant AMP thionins, defensins, and cyclotides, which have anticancer activities. Here, we provide an overview of plant AMPs anticancer activities, with an emphasis on their mode of action, their selectivity, and their efficacy. PMID:25815333

D-amino acid substitution enhances the stability of antimicrobial peptide polybia-CP.

PubMed

Jia, Fengjing; Wang, Jiayi; Peng, Jinxiu; Zhao, Ping; Kong, Ziqing; Wang, Kairong; Yan, Wenjin; Wang, Rui

2017-10-01

With the increasing emergence of resistant microbes toward conventional antimicrobial agents, there is an urgent need for the development of antimicrobial agents with novel action mode. Antimicrobial peptides (AMPs) are believed to be one kind of ideal alternatives. However, AMPs can be easily degraded by protease, which limited their therapeutic use. In the present study, D-amino acid substitution strategy was employed to enhance the stability of polybia-CP. We investigated the stability of peptides against the degradation of trypsin and chymotrypsin by determining the antimicrobial activity or determining the HPLC profile of peptides after incubation with proteases. Our results showed that both the all D-amino acid derivative (D-CP) and partial D-lysine substitution derivative (D-lys-CP) have an improved stability against trypsin and chymotrypsin. Although D-CP takes left-hand α-helical conformation and D-lys-CP loses some α-helical content, both of the D-amino acid-substituted derivatives maintain their parental peptides' membrane active action mode. In addition, D-lys-CP showed a slight weaker antimicrobial activity than polybia-CP, but the hemolytic activity decreased greatly. These results suggest that D-CP and D-lys-CP can offer strategy to improve the property of AMPs and may be leading compounds for the development of novel antimicrobial agents. © The Author 2017. Published by Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Antimicrobial resistance trends among Salmonella isolates obtained from dairy cattle in the northeastern United States, 2004-2011.

PubMed

Cummings, Kevin J; Perkins, Gillian A; Khatibzadeh, Sarah M; Warnick, Lorin D; Altier, Craig

2013-04-01

Monitoring antimicrobial resistance trends among bacteria isolated from food animals and people is necessary to inform public policy regarding appropriate antimicrobial use. Our objectives were to describe the antimicrobial resistance status of Salmonella isolates from dairy cattle in the northeastern United States and to identify trends in resistance to various antimicrobial agents over time. Data were collected retrospectively for all bovine Salmonella isolates that were obtained from samples submitted to Cornell University's Animal Health Diagnostic Center between January 1, 2004 and December 31, 2011. Temporal trends in the prevalence of resistant Salmonella were investigated for each antimicrobial agent using the Cochran-Armitage trend test. Antimicrobial susceptibility testing was performed on 2745 bovine Salmonella isolates from clinical samples submitted during the study period. Overall resistance to each antimicrobial agent ranged from 0% (amikacin, ciprofloxacin, and nalidixic acid) to 72.0% (sulfadimethoxine). There was evidence of a significantly decreasing trend in prevalence of resistance to most agents: amoxicillin/clavulanic acid (AUG), ampicillin (AMP), cefoxitin (FOX), ceftiofur (TIO), ceftriaxone (AXO), chloramphenicol (CHL), chlortetracycline (CTET), florfenicol (FFN), kanamycin (KAN), neomycin (NEO), oxytetracycline (OXY), spectinomycin (SPE), streptomycin (STR), sulfadimethoxine (SDM), sulfisoxazole (FIS), and tetracycline (TET). Among the 265 isolates that were tested using the National Antimicrobial Resistance Monitoring System (NARMS) panel, the most common resistance patterns were pansusceptible (54.0%), AUG-AMP-FOX-TIO-AXO-CHL-KAN-STR-FIS-TET (18.1%), and AUG-AMP-FOX-TIO-AXO-CHL-STR-FIS-TET (12.1%). Increasing prevalence of S. enterica serovar Cerro over the course of the study period presumably had an impact on the observed resistance trends. Nevertheless, these results do not support the notion that the current level of antimicrobial

Chitosan preparations for wounds and burns: antimicrobial and wound-healing effects

PubMed Central

Dai, Tianhong; Tanaka, Masamitsu; Huang, Ying-Ying; Hamblin, Michael R

2011-01-01

Since its discovery approximately 200 years ago, chitosan, as a cationic natural polymer, has been widely used as a topical dressing in wound management owing to its hemostatic, stimulation of healing, antimicrobial, nontoxic, biocompatible and biodegradable properties. This article covers the antimicrobial and wound-healing effects of chitosan, as well as its derivatives and complexes, and its use as a vehicle to deliver biopharmaceuticals, antimicrobials and growth factors into tissue. Studies covering applications of chitosan in wounds and burns can be classified into in vitro, animal and clinical studies. Chitosan preparations are classified into native chitosan, chitosan formulations, complexes and derivatives with other substances. Chitosan can be used to prevent or treat wound and burn infections not only because of its intrinsic antimicrobial properties, but also by virtue of its ability to deliver extrinsic antimicrobial agents to wounds and burns. It can also be used as a slow-release drug-delivery vehicle for growth factors to improve wound healing. The large number of publications in this area suggests that chitosan will continue to be an important agent in the management of wounds and burns. PMID:21810057

Shell crosslinked nanoparticles carrying silver antimicrobials as therapeutics†

PubMed Central

Li, Yali; Hindi, Khadijah; Watts, Kristin M.; Taylor, Jane B.; Zhang, Ke; Li, Zicheng

2010-01-01

Amphiphilic polymer nanoparticles loaded with silver cations or/and N-heterocyclic carbene–silver complexes were assessed as antimicrobial agents against Gram-negative pathogens Escherichia coli and Pseudomonas aeruginosa. PMID:20024313

A cost-effectiveness comparison of the use of antimicrobial agents for treatment or prophylaxis of travelers' diarrhea.

PubMed

Reves, R R; Johnson, P C; Ericsson, C D; DuPont, H L

1988-11-01

We conducted a decision analysis to compare the cost-effectiveness of antimicrobial agents used for treatment with their use for prophylaxis of travelers' diarrhea. Estimates of the likelihood and the cost of various outcomes were obtained from a panel of experts using the Delphi group opinion technique. Treatment with sulfamethoxazole-trimethoprim for three days was compared with daily prophylaxis with sulfamethoxazole-trimethoprim or doxycycline. The cost-effectiveness of prophylaxis with either agent (75% to 83%) was greater than that of treatment (38%). Treatment would become more cost-effective than prophylaxis when the cumulative risk of acquiring travelers' diarrhea was less than 0.05 episodes per person per week or if the effectiveness of prophylaxis fell below 35% for doxycycline and 46% for sulfamethoxazole-trimethoprim. The most important contributor to the mean cost of travelers' diarrhea in this analysis was the cost associated with a day of incapacitation due to illness. On the basis of the results of this decision analysis, we conclude that prophylaxis of travelers' diarrhea is an option that should be considered for individual situations and recommend further studies of its cost-effectiveness.

Outcomes of an antimicrobial control program in a teaching hospital.

PubMed

Gentry, C A; Greenfield, R A; Slater, L N; Wack, M; Huycke, M M

2000-02-01

The clinical outcomes and cost-effectiveness of an antimicrobial control program (ACP) were studied. The impact of an ACP in a teaching hospital was analyzed by comparing clinical outcomes and intravenous antimicrobial costs over two two-year periods, the two years before the program and the first two years after the program's inception. Admission baseline data, length of stay, mortality, and readmission rates were gathered for each patient. Patients were identified by using the International Classification of Diseases. Multivariate logistic regression models were constructed for mortality and for lengths of stay of 12 or more days. The acquisition costs of intravenous antimicrobial agents for the second baseline year and the entire program period were tabulated and compared. The average daily inpatient census was determined. The ACP was associated with a 2.4-day decrease in length of stay and a reduction in mortality from 8.28% to 6.61%. Rates of readmission for infection within 30 days of discharge remained about the same. Inpatient pharmacy costs other than intravenous antimicrobials decreased an average of only 5.7% over the two program years, but the acquisition cost of intravenous antimicrobials for both program years yielded a total cost saving of $291,885, a reduction of 30.8%. The institution's average daily census fell 19% between the second baseline year and the second program year. An ACP directed by a clinical pharmacist trained in infectious diseases was associated with improvements in inpatient length of stay and mortality. The ACP decreased intravenous antimicrobial costs and facilitated the approval process for restricted and nonformulary antimicrobial agents.

Antimicrobial Activities of Clove and Thyme Extracts

PubMed Central

Nzeako, B C; Al-Kharousi, Zahra S N; Al-Mahrooqui, Zahra

2006-01-01

Objective: It has been postulated that geographical locations of the herbs affect the constituents of their essential oils and thus the degree of their antimicrobial action. This study examine two samples of clove obtained from Sri Lanka and Zanzibar and two samples of thyme from Iran and Oman to determine the antimicrobial potential of their extracted oils. Method: The active agents in each plant were extracted by steam distillation and by boiling. The antimicrobial activities of the extracts were determined at neat and by two-fold dilutions in well agar diffusion technique using Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Streptococcus pyogenes, Corynebacterium species, Salmonella species, Bacteroides fragilis and Candida albicans. Results: All oil extracts possessed antimicrobial activity against all bacteria and yeast tested. Their water extracts exhibited lower antimicrobial activity, though thyme aqueous extract was active only against S. aureus. The lowest concentration of antimicrobial activity (0.1% i.e., 1:1024) was obtained with thyme oil extract using Candida albicans. There was no significant difference in antimicrobial activity between clove obtained from Sri Lanka or Zanzibar or thyme obtained from Iran or Oman. Conclusion: Our experiment showed that the country of origin of the herbs has no effect on their antimicrobial activity. However, further work is necessary to ascertain why Candida albicans displayed remarkable degree of sensitivity with the extracts than all the other organisms test. PMID:21748125

Phenotypically anchored transcriptome profiling of developmental exposure to the antimicrobial agent, triclosan, reveals hepatotoxicity in embryonic zebrafish

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

Haggard, Derik E.

Triclosan (TCS) is an antimicrobial agent commonly found in a variety of personal care products and cosmetics. TCS readily enters the environment through wastewater and is detected in human plasma, urine, and breast milk due to its widespread use. Studies have implicated TCS as a disruptor of thyroid and estrogen signaling; therefore, research examining the developmental effects of TCS is warranted. In this study, we used embryonic zebrafish to investigate the developmental toxicity and potential mechanism of action of TCS. Embryos were exposed to graded concentrations of TCS from 6 to 120 hours post-fertilization (hpf) and the concentration where 80%more » of the animals had mortality or morbidity at 120 hpf (EC{sub 80}) was calculated. Transcriptomic profiling was conducted on embryos exposed to the EC{sub 80} (7.37 μM). We identified a total of 922 significant differentially expressed transcripts (FDR adjusted P-value ≤ 0.05; fold change ≥ 2). Pathway and gene ontology enrichment analyses identified biological networks and transcriptional hubs involving normal liver functioning, suggesting TCS may be hepatotoxic in zebrafish. Tissue-specific gene enrichment analysis further supported the role of the liver as a target organ for TCS toxicity. We also examined the in vitro bioactivity profile of TCS reported by the ToxCast screening program. TCS had a diverse bioactivity profile and was a hit in 217 of the 385 assay endpoints we identified. We observed similarities in gene expression and hepatic steatosis assays; however, hit data for TCS were more concordant with the hypothesized CAR/PXR activity of TCS from rodent and human in vitro studies. - Highlights: • Triclosan is a common antimicrobial agent with widespread human exposure. • Exposure to the triclosan EC{sub 80} causes robust gene expression changes in zebrafish. • The liver may be a target organ of triclosan toxicity in embryonic zebrafish. • Triclosan disrupts normal liver functioning and

Antimicrobial and Efflux Inhibitor Activity of Usnic Acid Against Mycobacterium abscessus.

PubMed

Ramis, Ivy B; Vianna, Júlia S; Reis, Ana Júlia; von Groll, Andrea; Ramos, Daniela F; Viveiros, Miguel; da Silva, Pedro E Almeida

2018-06-18

New drugs are needed to treat infections with antimicrobial-resistant Mycobacterium abscessus ; therefore, we evaluated usnic acid as an antimicrobial agent and efflux inhibitor (EI) against M. abscessus . Usnic acid showed antimicrobial activity, and synergistically, the EI verapamil increased this activity. In addition, when we evaluated the interaction of antimicrobials with usnic acid, the increase of their activity was observed. Finally, usnic acid showed an efflux inhibitory effect between the classical EIs verapamil and carbonyl cyanide m-chlorophenylhydrazine. In conclusion, usnic acid showed both antimicrobial and EI activity, indicating that this natural compound may be a promising scaffold for new drugs against this difficult-to-treat microorganism. Georg Thieme Verlag KG Stuttgart · New York.

Antimicrobial-resistant nontyphoidal Salmonella is associated with excess bloodstream infections and hospitalizations.

PubMed

Varma, Jay K; Molbak, Kåre; Barrett, Timothy J; Beebe, James L; Jones, Timothy F; Rabatsky-Ehr, Therese; Smith, Kirk E; Vugia, Duc J; Chang, Hwa-Gan H; Angulo, Frederick J

2005-02-15

Nontyphoidal Salmonella is a leading cause of foodborne illness. Few studies have explored the health consequences of antimicrobial-resistant Salmonella. The National Antimicrobial Resistance Monitoring System (NARMS) performs susceptibility testing on nontyphoidal Salmonella isolates. The Foodborne Diseases Active Surveillance Network (FoodNet) ascertains outcomes for patients with culture-confirmed Salmonella infection, in 9 states, each of which participates in NARMS. We analyzed the frequency of bloodstream infection and hospitalization among patients with resistant infections. Isolates defined as resistant to a clinically important agent were resistant to 1 or more of the following agents: ampicillin, ceftriaxone, ciprofloxacin, gentamicin, and/or trimethoprim-sulfamethoxazole. During 1996-2001, NARMS received 7370 serotyped, nontyphoidal Salmonella isolates from blood or stool. Bloodstream infection occurred more frequently among patients infected with an isolate resistant to > or =1 clinically important agent (adjusted odds ratio [OR], 1.6; 95% confidence interval [CI], 1.2-2.1), compared with patients with pansusceptible infection. During 1996-2001, FoodNet staff ascertained outcomes for 1415 patients who had isolates tested in NARMS. Hospitalization with bloodstream infection occurred more frequently among patients infected with an isolate resistant to > or =1 clinically important agent (adjusted OR, 3.1; 95% CI, 1.4-6.6), compared with patients with pansusceptible infection. Patients with antimicrobial-resistant nontyphoidal Salmonella infection were more likely to have bloodstream infection and to be hospitalized than were patients with pansusceptible infection. Mitigation of antimicrobial resistance in Salmonella will likely benefit human health.

Synthesis and antimicrobial studies of novel derivatives of 4-(4-formyl-3-phenyl-1H-pyrazol-1-yl)benzoic acid as potent anti-Acinetobacter baumanni agents

PubMed Central

Allison, Devin; Delancey, Evan; Ramey, Hunter; Williams, Conrad; Alsharif, Zakeyah Ali; Al-khattabi, Hessa; Ontko, Allyn; Gilmore, David

2017-01-01

Microbial resistance to antibiotics is a global concern. The World Health Organization (WHO) has identified antimicrobial resistance as one the three greatest threats for human beings in the 21st century. Without urgent and coordinated action, the world is moving toward a post-antibiotic era, in which normal infections or minor injuries may become fatal. In an effort to find new agents, we report the synthesis and antimicrobial activities of 40 novel 1,3-diphenyl pyrazole derivatives. These compounds have shown zones of growth inhibition up to 85 mm against Acinetobacter baumannii. We tested the active compounds against this Gram-negative bacterium in minimum inhibitory concentration (MIC) tests and found activity with concentration as low as 4 μg/mL. PMID:28065568

Synthesis and antimicrobial studies of novel derivatives of 4-(4-formyl-3-phenyl-1H-pyrazol-1-yl)benzoic acid as potent anti-Acinetobacter baumannii agents.

PubMed

Allison, Devin; Delancey, Evan; Ramey, Hunter; Williams, Conrad; Alsharif, Zakeyah Ali; Al-Khattabi, Hessa; Ontko, Allyn; Gilmore, David; Alam, Mohammad A

2017-02-01

Microbial resistance to antibiotics is a global concern. The World Health Organization (WHO) has identified antimicrobial resistance as one the three greatest threats for human beings in the 21st century. Without urgent and coordinated action, the world is moving toward a post-antibiotic era, in which normal infections or minor injuries may become fatal. In an effort to find new agents, we report the synthesis and antimicrobial activities of 40 novel 1,3-diphenyl pyrazole derivatives. These compounds have shown zones of growth inhibition up to 85mm against Acinetobacter baumannii. We tested the active compounds against this Gram-negative bacterium in minimum inhibitory concentration (MIC) tests and found activity with concentration as low as 4μg/mL. Published by Elsevier Ltd.

Nanostructures as promising tools for delivery of antimicrobial peptides.

PubMed

Brandelli, A

2012-07-01

Antimicrobial peptides have been extensively investigated for their potential applications as therapeutics and food biopreservatives. The antimicrobial activity may be impaired by the susceptibility for proteolytic degradation and undesirable interactions of the antimicrobial peptide in the biological environment. Development of nanostructures for entrapment and delivery of antimicrobial peptides may represent an alternative to the direct application of these substances. Lipid nanovesicles have been developed for encapsulation of antimicrobial peptides. Phosphatidylcholine is often employed in liposome manufacture, which is mostly achieved by the thin-film hydration method. Nanofibers may allow different physical modes of drug loading, including direct adsorption on the nanofiber surface or the assembly of drug-loaded nanoparticles. Self-assembled peptides reveal attractive features as nanostructures for applications in drug delivery and promising as antimicrobial agent for treatment of brain infections. Magnetic nanoparticles and nanotubules are also potential structures for entrapment of antimicrobial peptides. Nanoparticles can be also chemically modified with specific cell surface ligands to enhance cell adhesion and site specific delivery. This article reviews the most important nanostructures as promising tools for peptide delivery systems.

Antimalarial and antimicrobial activities of 8-Aminoquinoline-Uracils metal complexes

PubMed Central

Phopin, Kamonrat; Sinthupoom, Nujarin; Treeratanapiboon, Lertyot; Kunwittaya, Sarun; Prachayasittikul, Supaluk; Ruchirawat, Somsak; Prachayasittikul, Virapong

2016-01-01

8-Aminoquinoline (8AQ) derivatives have been reported to have antimalarial, anticancer, and antioxidant activities. This study investigated the potency of 8AQ-5-substituted (iodo and nitro) uracils metal (Mn, Cu, Ni) complexes (1-6) as antimalarial and antimicrobial agents. Interestingly, all of these metal complexes (1-6) showed fair antimalarial activities. Moreover, Cu complexes 2 (8AQ-Cu-5Iu) and 5 (8AQ-Cu-5Nu) exerted antimicrobial activities against Gram-negative bacteria including P. shigelloides and S. dysenteriae. The results reveal application of 8AQ and its metal complexes as potential compounds to be further developed as novel antimalarial and antibacterial agents. PMID:27103894

Antimalarial and antimicrobial activities of 8-Aminoquinoline-Uracils metal complexes.

PubMed

Phopin, Kamonrat; Sinthupoom, Nujarin; Treeratanapiboon, Lertyot; Kunwittaya, Sarun; Prachayasittikul, Supaluk; Ruchirawat, Somsak; Prachayasittikul, Virapong

2016-01-01

8-Aminoquinoline (8AQ) derivatives have been reported to have antimalarial, anticancer, and antioxidant activities. This study investigated the potency of 8AQ-5-substituted (iodo and nitro) uracils metal (Mn, Cu, Ni) complexes (1-6) as antimalarial and antimicrobial agents. Interestingly, all of these metal complexes (1-6) showed fair antimalarial activities. Moreover, Cu complexes 2 (8AQ-Cu-5Iu) and 5 (8AQ-Cu-5Nu) exerted antimicrobial activities against Gram-negative bacteria including P. shigelloides and S. dysenteriae. The results reveal application of 8AQ and its metal complexes as potential compounds to be further developed as novel antimalarial and antibacterial agents.

Physicochemical investigations of biogenic chitosan-silver nanocomposite as antimicrobial and anticancer agent.

PubMed

Arjunan, Nithya; Kumari, Henry Linda Jeeva; Singaravelu, Chandra Mohan; Kandasamy, Ruckmani; Kandasamy, Jothivenkatachalam

2016-11-01

Chitosan (CS), a seaweed polysaccharide is a natural macromolecule which is widely being used in medical applications because of its distinctive antimicrobial and anticancer properties. Silver, a noble metal, is also receiving wide attention for its potential usage in antimicrobial and anticancer therapeutics. In this study, an effective way of reduction of silver using chitosan at varying reaction temperatures and an optimised concentration of silver were performed. The optical, structural, spectral, morphological and elemental studies of the biosynthesized chitosan-silver (CS-Ag) nanocomposites were characterized by several techniques. The synthesized CS-Ag nanocomposites exhibit particle size around 20nm and were further exploited for potent biological applications in nanomedicine due to their nanometric sizes and biocompatibility of chitosan. The antimicrobial activity of the biosynthesized CS-Ag nanocomposites exhibits zone of inhibition ranged between 09.666±0.577 and 19.000±1.000 (mm). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were from 8 to 128μgmL -1 and 16 to 256μgmL -1 respectively, with the highest antimicrobial activity shown against Gram-negative Salmonella sp. The synergistic effect of chitosan and silver as a composite in nanometric size revealed significant IC 50 value of 29.35μgmL -1 and a maximum of 95.56% inhibition at 100μgmL -1 against A549 lung cancer cell line, resulting in potent anticancer effect. Copyright © 2016 Elsevier B.V. All rights reserved.

Antimicrobial resistance of zoonotic and commensal bacteria in Europe: the missing link between consumption and resistance in veterinary medicine.

PubMed

Garcia-Migura, Lourdes; Hendriksen, Rene S; Fraile, Lorenzo; Aarestrup, Frank M

2014-05-14

The emergence of resistance in food animals has been associated to the consumption of antimicrobials in veterinary medicine. Consequently, monitoring programs have been designed to monitor the occurrence of antimicrobial resistant bacteria. This study analyses the amount of antimicrobial agents used in nine European countries from 2005 to 2011, and compares by univariate analysis the correlations between consumptions of each of the following antimicrobial classes; tetracycline, penicillins, cephalosporins, quinolones and macrolides. An overview of resistance in zoonotic and commensal bacteria in Europe focusing on Salmonella, Escherichia coli, Campylobacter sp. and Enterococcus sp., during the same period of time based on monitoring programs is also assessed. With the exception of cephalosporins, linear regressions showed strong positive associations between the consumption of the four different antimicrobial classes. Substantial differences between countries were observed in the amount of antimicrobials used to produce 1 kg of meat. Moreover, large variations in proportions of resistant bacteria were reported by the different countries, suggesting differences in veterinary practice. Despite the withdrawn of a specific antimicrobial from "on farm" use, persistence over the years of bacteria resistant to this particular antimicrobial agent, was still observed. There were also differences in trends of resistance associated to specific animal species. In order to correlate the use of antimicrobial agents to the presence of resistance, surveillance of antimicrobial consumption by animal species should be established. Subsequently, intervention strategies could be designed to minimize the occurrence of resistance. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantitative Assessment of Combination Antimicrobial Therapy against Multidrug-Resistant Acinetobacter baumannii▿

PubMed Central

Lim, Tze-Peng; Ledesma, Kimberly R.; Chang, Kai-Tai; Hou, Jing-Guo; Kwa, Andrea L.; Nikolaou, Michael; Quinn, John P.; Prince, Randall A.; Tam, Vincent H.

2008-01-01

Treatment of multidrug-resistant bacterial infections poses a therapeutic challenge to clinicians; combination therapy is often the only viable option for multidrug-resistant infections. A quantitative method was developed to assess the combined killing abilities of antimicrobial agents. Time-kill studies (TKS) were performed using a multidrug-resistant clinical isolate of Acinetobacter baumannii with escalating concentrations of cefepime (0 to 512 mg/liter), amikacin (0 to 256 mg/liter), and levofloxacin (0 to 64 mg/liter). The bacterial burden data in single and combined (two of the three agents with clinically achievable concentrations in serum) TKS at 24 h were mathematically modeled to provide an objective basis for comparing various antimicrobial agent combinations. Synergy and antagonism were defined as interaction indices of <1 and >1, respectively. A hollow-fiber infection model (HFIM) simulating various clinical (fluctuating concentrations over time) dosing exposures was used to selectively validate our quantitative assessment of the combined killing effect. Model fits in all single-agent TKS were satisfactory (r2 > 0.97). An enhanced combined overall killing effect was seen in the cefepime-amikacin combination (interactive index, 0.698; 95% confidence interval [CI], 0.675 to 0.722) and the cefepime-levofloxacin combination (interactive index, 0.929; 95% CI, 0.903 to 0.956), but no significant difference in the combined overall killing effect for the levofloxacin-amikacin combination was observed (interactive index, 0.994; 95% CI, 0.982 to 1.005). These assessments were consistent with observations in HFIM validation studies. Our method could be used to objectively rank the combined killing activities of two antimicrobial agents when used together against a multidrug-resistant A. baumannii isolate. It may offer better insights into the effectiveness of various antimicrobial combinations and warrants further investigations. PMID:18505848

Emerging Resistance, New Antimicrobial Agents  …  but No Tests! The Challenge of Antimicrobial Susceptibility Testing in the Current US Regulatory Landscape.

PubMed

Humphries, R M; Hindler, J A

2016-07-01

Accurate and timely performance of antimicrobial susceptibility testing (AST) by the clinical laboratory is paramount to combating antimicrobial resistance. The ability of laboratories in the United States to effectively perform ASTs is challenged by several factors. Some, such as new resistance mechanisms and the associated evolution of testing recommendations and breakpoints, are inevitable. Others are entirely man-made. These include unnecessarily strict US Food and Drug Administration (FDA) limitations on how commercial AST systems can be used for diagnostic testing, the absence of up-to-date performance data on these systems, and the lack of commercially available FDA-cleared tests for newer antimicrobial agents or for older agents with updated breakpoints. This viewpoint will highlight contemporary AST challenges faced by the clinical laboratory, and propose some solutions. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Antimicrobial Resistance and Reduced Susceptibility in Clostridium difficile: Potential Consequences for Induction, Treatment, and Recurrence of C. difficile Infection

PubMed Central

Baines, Simon D.; Wilcox, Mark H.

2015-01-01

Clostridium difficile infection (CDI) remains a substantial burden on healthcare systems and is likely to remain so given our reliance on antimicrobial therapies to treat bacterial infections, especially in an aging population in whom multiple co-morbidities are common. Antimicrobial agents are a key component in the aetiology of CDI, both in the establishment of the infection and also in its treatment. The purpose of this review is to summarise the role of antimicrobial agents in primary and recurrent CDI; assessing why certain antimicrobial classes may predispose to the induction of CDI according to a balance between antimicrobial activity against the gut microflora and C. difficile. Considering these aspects of CDI is important in both the prevention of the infection and in the development of new antimicrobial treatments. PMID:27025625

Fatty acid conjugation enhances the activities of antimicrobial peptides.

PubMed

Li, Zhining; Yuan, Penghui; Xing, Meng; He, Zhumei; Dong, Chuanfu; Cao, Yongchang; Liu, Qiuyun

2013-04-01

Antimicrobial peptides are small molecules that play a crucial role in innate immunity in multi-cellular organisms, and usually expressed and secreted constantly at basal levels to prevent infection, but local production can be augmented upon an infection. The clock is ticking as rising antibiotic abuse has led to the emergence of many drug resistance bacteria. Due to their broad spectrum antibiotic and antifungal activities as well as anti-viral and anti-tumor activities, efforts are being made to develop antimicrobial peptides into future microbial agents. This article describes some of the recent patents on antimicrobial peptides with fatty acid conjugation. Potency and selectivity of antimicrobial peptide can be modulated with fatty acid tails of variable length. Interaction between membranes and antimicrobial peptides was affected by fatty acid conjugation. At concentrations above the critical miscelle concentration (CMC), propensity of solution selfassembly hampered binding of the peptide to cell membranes. Overall, fatty acid conjugation has enhanced the activities of antimicrobial peptides, and occasionally it rendered inactive antimicrobial peptides to be bioactive. Antimicrobial peptides can not only be used as medicine but also as food additives.

Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained.

PubMed

von Woedtke, T; Schlüter, B; Pflegel, P; Lindequist, U; Jülich, W D

1999-06-01

The antimicrobial efficacy as well as the content of preservative agents of six commercially available grapefruit seed extracts were examined. Five of the six extracts showed a high growth inhibiting activity against the test germs Bacillus subtilis SBUG 14, Micrococcus flavus SBUG 16, Staphylococcus aureus SBUG 11, Serratia marcescens SBUG 9, Escherichia coli SBUG 17, Proteus mirabilis SBUG 47, and Candida maltosa SBUG 700. In all of the antimicrobial active grapefruit seed extracts, the preservative benzethonium chloride was detected by thin layer chromatography. Additionally, three extracts contained the preserving substances triclosan and methyl parabene. In only one of the grapefruit seed extracts tested no preservative agent was found. However, with this extract as well as with several self-made extracts from seed and juiceless pulp of grapefruits (Citrus paradisi) no antimicrobial activity could be detected (standard serial broth dilution assay, agar diffusion test). Thus, it is concluded that the potent as well as nearly universal antimicrobial activity being attributed to grapefruit seed extract is merely due to the synthetic preservative agents contained within. Natural products with antimicrobial activity do not appear to be present.

Antibiotic-resistant bacteria show widespread collateral sensitivity to antimicrobial peptides.

PubMed

Lázár, Viktória; Martins, Ana; Spohn, Réka; Daruka, Lejla; Grézal, Gábor; Fekete, Gergely; Számel, Mónika; Jangir, Pramod K; Kintses, Bálint; Csörgő, Bálint; Nyerges, Ákos; Györkei, Ádám; Kincses, András; Dér, András; Walter, Fruzsina R; Deli, Mária A; Urbán, Edit; Hegedűs, Zsófia; Olajos, Gábor; Méhi, Orsolya; Bálint, Balázs; Nagy, István; Martinek, Tamás A; Papp, Balázs; Pál, Csaba

2018-06-01

Antimicrobial peptides are promising alternative antimicrobial agents. However, little is known about whether resistance to small-molecule antibiotics leads to cross-resistance (decreased sensitivity) or collateral sensitivity (increased sensitivity) to antimicrobial peptides. We systematically addressed this question by studying the susceptibilities of a comprehensive set of 60 antibiotic-resistant Escherichia coli strains towards 24 antimicrobial peptides. Strikingly, antibiotic-resistant bacteria show a high frequency of collateral sensitivity to antimicrobial peptides, whereas cross-resistance is relatively rare. We identify clinically relevant multidrug-resistance mutations that increase bacterial sensitivity to antimicrobial peptides. Collateral sensitivity in multidrug-resistant bacteria arises partly through regulatory changes shaping the lipopolysaccharide composition of the bacterial outer membrane. These advances allow the identification of antimicrobial peptide-antibiotic combinations that enhance antibiotic activity against multidrug-resistant bacteria and slow down de novo evolution of resistance. In particular, when co-administered as an adjuvant, the antimicrobial peptide glycine-leucine-amide caused up to 30-fold decrease in the antibiotic resistance level of resistant bacteria. Our work provides guidelines for the development of efficient peptide-based therapies of antibiotic-resistant infections.

Antimicrobial edible films and coatings for fresh and minimally processed fruits and vegetables: a review.

PubMed

Valencia-Chamorro, Silvia A; Palou, Lluís; Del Río, Miguel A; Pérez-Gago, María B

2011-01-01

The use of edible films and coatings is an environmentally friendly technology that offers substantial advantages for shelf-life increase of many food products including fruits and vegetables. The development of new natural edible films and coatings with the addition of antimicrobial compounds to preserve fresh and minimally processed fruits and vegetables is a technological challenge for the industry and a very active research field worldwide. Antimicrobial agents have been successfully added to edible composite films and coatings based on polysaccharides or proteins such as starch, cellulose derivatives, chitosan, alginate, fruit puree, whey protein isolated, soy protein, egg albumen, wheat gluten, or sodium caseinate. This paper reviews the development of edible films and coatings with antimicrobial activity, typically through the incorporation of antimicrobial food additives as ingredients, the effect of these edible films on the control of target microorganisms, the influence of antimicrobial agents on mechanical and barrier properties of stand-alone edible films, and the effect of the application of antimicrobial edible coatings on the quality of fresh and fresh-cut fruits and vegetables.

French multicenter study involving eight test sites for radiometric determination of activities of 10 antimicrobial agents against Mycobacterium avium complex.

PubMed Central

Rastogi, N; Bauriaud, R M; Bourgoin, A; Carbonnelle, B; Chippaux, C; Gevaudan, M J; Goh, K S; Moinard, D; Roos, P

1995-01-01

The radiometric BACTEC 460-TB methodology has filled an increased need in the screening of a wide range of antimicrobial agents against Mycobacterium avium (MAC) isolates on a patient-to-patient basis. In this context, a multicenter study involving eight test sites across France was performed to determine the MICs of 10 antimicrobial agents for MAC organisms. The aim of the investigation was to compare the in vitro activities of D-cycloserine, ethambutol, ethionamide, rifampin, amikacin, streptomycin, ciprofloxacin, sparfloxacin, clofazimine, and clarithromycin against MAC isolates. All of the test sites received the same clinical isolates of MAC, and the MICs were determined by a common protocol. The overall interlaboratory reproducibility of the MICs within +/- 1 dilution of the modal MICs varied from 79.70 to 100% (mean, 95.2% +/- 2.1%), whereas overall agreement of the MICs among the test sites varied from a mean of 91% +/- 4.1% to a mean of 98 +/- 1.3%. We confirmed that the proposed methodology is easy, accurate, and sufficiently reproducible to be used routinely in a clinical laboratory. Despite variations in the MICs of the same drug among strains, no link between the origin of MAC isolates (from human immunodeficiency virus-positive or -negative patients) and their drug susceptibilities was established. On the basis of the MICs that inhibited 50 and 90% of isolates tested for the drugs used, clarithromycin, clofazimine, ethambutol, and streptomycin were the most uniformly active against MAC; this was followed by amikacin, rifampin, and sparfloxacin. On the other hand, ciprofloxacin, D-cycloserine, and ethionamide showed only marginal in vitro activities. PMID:7793865

Antimicrobial Drug Prescription and Neisseria gonorrhoeae Susceptibility, United States, 2005–2013

PubMed Central

Bartoces, Monina G.; Soge, Olusegun O.; Riedel, Stefan; Kubin, Grace; Del Rio, Carlos; Papp, John R.; Hook, Edward W.; Hicks, Lauri A.

2017-01-01

We investigated whether outpatient antimicrobial drug prescribing is associated with Neisseria gonorrhoeae antimicrobial drug susceptibility in the United States. Using susceptibility data from the Gonococcal Isolate Surveillance Project during 2005–2013 and QuintilesIMS data on outpatient cephalosporin, macrolide, and fluoroquinolone prescribing, we constructed multivariable linear mixed models for each antimicrobial agent with 1-year lagged annual prescribing per 1,000 persons as the exposure and geometric mean MIC as the outcome of interest. Multivariable models did not demonstrate associations between antimicrobial drug prescribing and N. gonorrhoeae susceptibility for any of the studied antimicrobial drugs during 2005–2013. Elucidation of epidemiologic factors contributing to resistance, including further investigation of the potential role of antimicrobial drug use, is needed. PMID:28930001

Antimicrobial Impacts of Essential Oils on Food Borne-Pathogens.

PubMed

Ozogul, Yesim; Kuley, Esmeray; Ucar, Yilmaz; Ozogul, Fatih

2015-01-01

The antimicrobial activity of twelve essential oil (pine oil, eucalyptus, thyme, sage tea, lavender, orange, laurel, lemon, myrtle, lemon, rosemary and juniper) was tested by a disc diffusion method against food borne pathogens (Escherichia coli, Salmonella paratyphi A, Klebsiella pneumoniae, Yersinia enterocolitica, Pseudomonas aeruginosa, Aeromonas hydrophila, Campylobacter jejuni, Enterococcus faecalis, Staphylococcus aureus). The major components in essential oils were monoterpenes hydrocarbons, α-pinene, limonene; monoterpene phenol, carvacrol and oxygenated monoterpenes, camphor, 1,8-cineole, eucalyptol, linalool and linalyl acetate. Although the antimicrobial effect of essential oils varied depending on the chemical composition of the essential oils and specific microorganism tested, majority of the oils exhibited antibacterial activity against one or more strains. The essential oil with the lowest inhibition zones was juniper with the values varied from 1.5 to 6 mm. However, the components of essential oil of thyme and pine oil are highly active against food borne pathogen, generating the largest inhibition zones for both gram negative and positive bacteria (5.25-28.25 mm vs. 12.5-30 mm inhibition zones). These results indicate the possible use of the essential oils on food system as antimicrobial agents against food-borne pathogen. The article also offers some promising patents on applications of essential oils on food industry as antimicrobial agent.

Antimicrobial graphene family materials: Progress, advances, hopes and fears.

PubMed

Lukowiak, Anna; Kedziora, Anna; Strek, Wieslaw

2016-10-01

Graphene-based materials have become very popular bionanotechnological instruments in the last few years. Since 2010, the graphene family materials have been recognized as worthy of attention due to its antimicrobial properties. Functionalization of graphene (or rather graphene oxide) surface creates the possibilities to obtain efficient antimicrobial agents. In this review, progress and advances in this field in the last few years are described and discussed. Special attention is devoted to materials based on graphene oxide in which specifically selected components significantly modify biological activity of this carbon structure. Short introduction concerns the physicochemical properties of the graphene family materials. In the section on antimicrobial properties, proposed mechanisms of activity against microorganisms are given showing enhanced action of nanocomposites also under light irradiation (photoinduced activity). Another important feature, i.e. toxicity against eukaryotic cells, is presented with up-to-date data. Taking into account all the information on the properties of the described materials and usefulness of the graphene family as antimicrobial agents, hopes and fears concerning their application are discussed. Finally, some examples of promising usage in medicine and other fields, e.g. in phytobiology and water remediation, are shown. Copyright © 2016 Elsevier B.V. All rights reserved.

Antimicrobial Activity of Lactoferrin-Related Peptides and Applications in Human and Veterinary Medicine.

PubMed

Bruni, Natascia; Capucchio, Maria Teresa; Biasibetti, Elena; Pessione, Enrica; Cirrincione, Simona; Giraudo, Leonardo; Corona, Antonio; Dosio, Franco

2016-06-11

Antimicrobial peptides (AMPs) represent a vast array of molecules produced by virtually all living organisms as natural barriers against infection. Among AMP sources, an interesting class regards the food-derived bioactive agents. The whey protein lactoferrin (Lf) is an iron-binding glycoprotein that plays a significant role in the innate immune system, and is considered as an important host defense molecule. In search for novel antimicrobial agents, Lf offers a new source with potential pharmaceutical applications. The Lf-derived peptides Lf(1-11), lactoferricin (Lfcin) and lactoferrampin exhibit interesting and more potent antimicrobial actions than intact protein. Particularly, Lfcin has demonstrated strong antibacterial, anti-fungal and antiparasitic activity with promising applications both in human and veterinary diseases (from ocular infections to osteo-articular, gastrointestinal and dermatological diseases).

Antimicrobial Protection of Marsupial Pouch Young

PubMed Central

Cheng, Yuanyuan; Belov, Katherine

2017-01-01

Marsupials diverged from eutherian mammals about 148 million years ago and represent a unique lineage of mammals with distinctive morphological and reproductive characteristics. Marsupials have significantly shorter gestation periods than eutherians. Pregnancy typically ranges from 15 to 35 days, with young being born at a very early developmental stage and lacking differentiated lymphoid tissues and mature effector cells. Recent microbiome studies of the marsupial pouch revealed that marsupial young can face intense microbial challenges after birth, as the pouch contains a broad range of Gram-positive and Gram-negative bacteria. Antimicrobials are believed to play a significant role in the immune protection of marsupial newborns during their pouch life. The skin of the post-reproductive pouch secretes antimicrobial lysozyme and dermcidin, which may contribute to the decreased density of certain bacteria in the pouch. A range of antimicrobial agents, such as immunoglobulins, lysozyme, transferrin, and cathelicidins, have been identified in marsupial milk. Antimicrobial assays have revealed that marsupial cathelicidins have broad-spectrum activity against a variety of bacteria and fungi, including several multi-drug resistant strains. In this article, we will review the action mechanisms of these antimicrobial compounds and discuss how they protect marsupial newborns from potentially pathogenic bacteria inside the pouch. We will also discuss the potential of marsupial antimicrobial compounds as a source of novel antibiotics. PMID:28326070

Development of antimicrobial active packaging materials based on gluten proteins.

PubMed

Gómez-Heincke, Diana; Martínez, Inmaculada; Partal, Pedro; Guerrero, Antonio; Gallegos, Críspulo

2016-08-01

The incorporation of natural biocide agents into protein-based bioplastics, a source of biodegradable polymeric materials, manufactured by a thermo-mechanical method is a way to contribute to a sustainable food packaging industry. This study assesses the antimicrobial activity of 10 different biocides incorporated into wheat gluten-based bioplastics. The effect that formulation, processing, and further thermal treatments exert on the thermo-mechanical properties, water absorption characteristics and rheological behaviour of these materials is also studied. Bioplastics containing six of the 10 examined bioactive agents have demonstrated suitable antimicrobial activity at 37 °C after their incorporation into the bioplastic. Moreover, the essential oils are able to create an antimicrobial atmosphere within a Petri dish. Depending on the selected biocide, its addition may alter the bioplastics protein network in a different extent, which leads to materials exhibiting less water uptake and different rheological and thermo-mechanical behaviours. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Interscience Conference on Antimicrobial Agents and Chemotherapy--49th annual meeting. Part 2. 12-15 September 2009, San Francisco, CA, USA.

PubMed

Turner, Ben; Murch, Lisa

2009-11-01

The Interscience Conference on Antimicrobial Agents and Chemotherapy held in San Francisco included topics covering new therapeutic developments for the treatment of infectious diseases. This conference report highlights selected presentations on several antibiotics in development including a broad-spectrum penem beta-lactam antibiotic, a novel siderophore monobactam, as well as other novel antibiotics. Investigational drugs discussed include sulopenem and sulopenem etzadroxil (both Pfizer Inc), BAL-30072 (Basilea Pharmaceutica International Ltd), TP-120 and TP-787 (both Tetraphase Pharmaceuticals Inc), NAI-107 (New Anti Infectives Consortium/NexThera Biosciences) and ABI-200 (AdRem Biotech/US Department of Agriculture).

Synthesis of symmetrical and asymmetrical azines from hydrazones and/or ferrocenecarboxaldehyde as potential antimicrobial-antitumor agents

NASA Astrophysics Data System (ADS)

Lasri, Jamal; Aly, Magda M.; Eltayeb, Naser Eltaher; Babgi, Bandar A.

2018-07-01

9-Fluorenone azine 2a and benzophenone azine 2b were synthesized, respectively, by treatment of 9-fluorenone hydrazone 1a or benzophenone hydrazone 1b with FeCl3 in chloroform. Ferrocenecarboxaldehyde 3 reacts with 1a or 1b, in ethanol, to furnish novel asymmetrical azine products 1-((ferrocenyl)methylene)-2-(9H-fluoren-9-ylidene)hydrazine 3a or 1-((ferrocenyl)methylene)-2-(diphenylmethylene)hydrazine 3b, respectively. The compounds were characterized by IR,1H, 13C and DEPT-135 NMR spectroscopy, high resolution ESI+-MS or EI, and also by single crystal X-ray diffraction analysis (in the case of 2b and 3b). The contribution of the azine functional group (3a) in the LUMO orbital was justified by observing a red shift in the MLCT upon its protonation. The antimicrobial activities of 2a, 2b, 3a and 3b were determined against some Gram-positive and Gram-negative bacteria in addition to Candida albicans and Aspergillus niger using paper disc diffusion method. Moderate antibacterial activities were found for 3a and 3b while weak activities were recorded for 2a and 2b compared to Ampicillin, positive control. No antifungal or antitumor activities were found for all the tested compounds, except 3a which showed antitumor activity. Low toxicity was recorded for 3a and 3b using Artemia salina as test organism. Hence, the prepared products 3a and 3b can be used as antimicrobial agents due to their antibacterial activities and low cell toxicity.

Encrypted Antimicrobial Peptides from Plant Proteins.

PubMed

Ramada, M H S; Brand, G D; Abrão, F Y; Oliveira, M; Filho, J L Cardozo; Galbieri, R; Gramacho, K P; Prates, M V; Bloch, C

2017-10-16

Examples of bioactive peptides derived from internal sequences of proteins are known for decades. The great majority of these findings appear to be fortuitous rather than the result of a deliberate and methodological-based enterprise. In the present work, we describe the identification and the biological activities of novel antimicrobial peptides unveiled as internal fragments of various plant proteins founded on our hypothesis-driven search strategy. All putative encrypted antimicrobial peptides were selected based upon their physicochemical properties that were iteratively selected by an in-house computer program named Kamal. The selected peptides were chemically synthesized and evaluated for their interaction with model membranes. Sixteen of these peptides showed antimicrobial activity against human and/or plant pathogens, some with a wide spectrum of activity presenting similar or superior inhibition efficacy when compared to classical antimicrobial peptides (AMPs). These original and previously unforeseen molecules constitute a broader and undisputable set of evidences produced by our group that illustrate how the intragenic concept is a workable reality and should be carefully explored not only for microbicidal agents but also for many other biological functions.

Synthetic biology platform technologies for antimicrobial applications.

PubMed

Braff, Dana; Shis, David; Collins, James J

2016-10-01

The growing prevalence of antibiotic resistance calls for new approaches in the development of antimicrobial therapeutics. Likewise, improved diagnostic measures are essential in guiding the application of targeted therapies and preventing the evolution of therapeutic resistance. Discovery platforms are also needed to form new treatment strategies and identify novel antimicrobial agents. By applying engineering principles to molecular biology, synthetic biologists have developed platforms that improve upon, supplement, and will perhaps supplant traditional broad-spectrum antibiotics. Efforts in engineering bacteriophages and synthetic probiotics demonstrate targeted antimicrobial approaches that can be fine-tuned using synthetic biology-derived principles. Further, the development of paper-based, cell-free expression systems holds promise in promoting the clinical translation of molecular biology tools for diagnostic purposes. In this review, we highlight emerging synthetic biology platform technologies that are geared toward the generation of new antimicrobial therapies, diagnostics, and discovery channels. Copyright © 2016 Elsevier B.V. All rights reserved.

A potential photocatalytic, antimicrobial and anticancer activity of chitosan-copper nanocomposite.

PubMed

Arjunan, Nithya; Singaravelu, Chandra Mohan; Kulanthaivel, Jeganathan; Kandasamy, Jothivenkatachalam

2017-11-01

In this study, chitosan-copper (CS-Cu) nanocomposite was synthesized without the aid of any external chemical reducing agents. The optical, structural, spectral, thermal and morphological analyses were carried out by several techniques. The prepared nanocomposite acts as a photocatalyst for the removal of Rhodamine B (RhB) and Conge red (CR) dyes under visible light irradiation. The pseudo first order kinetics was derived according to Langmuir-Hinshelwood (L-H) model. The nanocomposite also proved to be an excellent antimicrobial agent against Gram-positive and Gram-negative bacteria; and also show activity against fungus. The advanced material was used for the major research areas which include photocatalytic materials for waste water treatment; biological applications in the development of drug resistant antimicrobials and anticancer agents. Copyright © 2017 Elsevier B.V. All rights reserved.

High-Velocity Microsprays Enhance Antimicrobial Activity in Streptococcus mutans Biofilms.

PubMed

Fabbri, S; Johnston, D A; Rmaile, A; Gottenbos, B; De Jager, M; Aspiras, M; Starke, E M; Ward, M T; Stoodley, P

2016-12-01

Streptococcus mutans in dental plaque biofilms play a role in caries development. The biofilm's complex structure enhances the resistance to antimicrobial agents by limiting the transport of active agents inside the biofilm. The authors assessed the ability of high-velocity water microsprays to enhance delivery of antimicrobials into 3-d-old S. mutans biofilms. Biofilms were exposed to a 90° or 30° impact, first using a 1-µm tracer bead solution (10 9 beads/mL) and, second, a 0.2% chlorhexidine (CHX) or 0.085% cetylpyridinium chloride (CPC) solution. For comparison, a 30-s diffusive transport and simulated mouthwash were also performed. Confocal microscopy was used to determine number and relative bead penetration depth into the biofilm. Assessment of antimicrobial penetration was determined by calculating the killing depth detected by live/dead viability staining. The authors first demonstrated that the microspray was able to deliver significantly more microbeads deeper in the biofilm compared with diffusion and mouthwashing exposures. Next, these experiments revealed that the microspray yielded better antimicrobial penetration evidenced by deeper killing inside the biofilm and a wider killing zone around the zone of clearance than diffusion alone. Interestingly the 30° impact in the distal position delivered approximately 16 times more microbeads and yielded approximately 20% more bacteria killing (for both CHX and CPC) than the 90° impact. These data suggest that high-velocity water microsprays can be used as an effective mechanism to deliver microparticles and antimicrobials inside S. mutans biofilms. High shear stresses generated at the biofilm-burst interface might have enhanced bead and antimicrobial delivery inside the remaining biofilm by combining forced advection into the biofilm matrix and physical restructuring of the biofilm itself. Further, the impact angle has potential to be optimized both for biofilm removal and active agents' delivery inside

Role of Combination Antimicrobial Therapy for Vancomycin-Resistant Enterococcus faecium Infections: Review of the Current Evidence.

PubMed

Yim, Juwon; Smith, Jordan R; Rybak, Michael J

2017-05-01

Enterococcus species are the second most common cause of nosocomial infections in the United States and are particularly concerning in critically ill patients with preexisting comorbid conditions. Rising resistance to antimicrobials that were historically used as front-line agents for treatment of enterococcal infections, such as ampicillin, vancomycin, and aminoglycosides, further complicates the treatment of these infections. Of particular concern are Enterococcus faecium strains that are associated with the highest rate of vancomycin resistance. The introduction of antimicrobial agents with specific activity against vancomycin-resistant Enterococcus (VRE) faecium including daptomycin, linezolid, quinupristin-dalfopristin, and tigecycline did not completely resolve this clinical dilemma. In this review, the mechanisms of action and resistance to currently available anti-VRE antimicrobial agents including newer agents such as oritavancin and dalbavancin will be presented. In addition, novel combination therapies including β-lactams and fosfomycin, and the promising results from in vitro, animal studies, and clinical experience in the treatment of VRE faecium will be discussed. © 2017 Pharmacotherapy Publications, Inc.

Evaluation of antimicrobial activity of glycerol monolaurate nanocapsules against American foulbrood disease agent and toxicity on bees.

PubMed

Lopes, Leonardo Q S; Santos, Cayane G; de Almeida Vaucher, Rodrigo; Gende, Liesel; Raffin, Renata P; Santos, Roberto C V

2016-08-01

The American Foulbrood Disease (AFB) is a fatal larval bee infection. The etiologic agent is the bacterium Paenibacillus larvae. The treatment involves incineration of all contaminated materials, leading to high losses. The Glycerol Monolaurate (GML) is a known antimicrobial potential compound, however its use is reduced due to its low solubility in water and high melting point. The nanoencapsulation of some drugs offers several advantages like improved stability and solubility in water. The present study aimed to evaluate the antimicrobial activity against P. larvae and the toxicity in bees of GML nanoparticles. The nanocapsules were produced and presented mean diameter of 210 nm, polydispersity index of 0.044, and zeta potential of -23.4 mV demonstrating the acceptable values to predict a stable system. The microdilution assay showed that it is necessary 142 and 285 μg/mL of GML nanocapsules to obtain a bacteriostatic and bactericidal effect respectively. The time-kill curve showed the controlled release of compound, exterminating the microorganism after 24 h. The GML nanocapsules were able to kill the spore form of Paenibacillus larvae while the GML do not cause any effect. The assay in bees showed that the GML has a high toxicity while the GML nanoparticles showed a decrease on toxic effects. Concluding, the formulation shows positive results in the action to combat AFB besides not causing damage to bees. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanoparticles for antimicrobial purposes in Endodontics: A systematic review of in vitro studies.

PubMed

Samiei, Mohammad; Farjami, Afsaneh; Dizaj, Solmaz Maleki; Lotfipour, Farzaneh

2016-01-01

Antimicrobial nanoparticles with enhanced physiochemical properties have attracted attention as modern antimicrobials, especially in the complicated oral cavity environment. The goal of the present article is to review the current state of nanoparticles used for antimicrobial purposes in root canal infections. A review was conducted in electronic databases using MeSH keywords to identify relevant published literature in English. The analysis and eligibility criteria were documented according to the Preferred Reporting Items for Systematic Reviews and Meta Analysis (PRISMA-guidelines). No restrictions on publication date were imposed. Data regarding root canal disinfections, general antimicrobial mechanisms of nanoparticles, type of nanoparticles as antimicrobial agent and antimicrobial effect of nanoparticles in endodontics were collected and subjected to descriptive data analysis. The literature search in electronic databases according to the inclusion criteria provided 83 titles and abstracts. Among them 15 papers were related to antimicrobial effect of nanoparticles in Endodontics. Silver nanoparticles with sustainable activity were the most studied agent for its antimicrobial behavior in root canal infection. Aided polymeric nanoparticles with photo or ultrasound, glass bioactive nanoparticles as well as Calcium derivative based nanoparticles, with improved activity in comparison with the non-nano counterparts, are of importance in infection control of dental root canal. Bioactive Non-organic nanoparticles with structural capabilities present enhanced antimicrobial activity in root canal infections. All included studies showed an enhanced or at least equal effect of nanoparticulate systems to combat dental root canal infections compared to conventional antimicrobial procedures. However, it is crucial to understand their shortcomings and their probable cellular effects and toxicity as well as environmental effects. Copyright © 2015 Elsevier B.V. All rights

Antimicrobial Activity of Nanoemulsion in Combination with Cetylpyridinium Chloride in Multidrug-Resistant Acinetobacter baumannii

DTIC Science & Technology

2013-08-01

antimicrobial nanoparticles, chelating agents, and peptides . ACKNOWLEDGMENTS We thank Stephanie A. Brown and Hunter Radetsky for technical support. Funding...AUG 2013 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Antimicrobial activity of nanoemulsion in combination with...unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Antimicrobial Activity of Nanoemulsion in Combination

Antimicrobial and Attractant Roles for Chemerin in the Oral Cavity during Inflammatory Gum Disease

PubMed Central

Godlewska, Urszula; Brzoza, Piotr; Sroka, Aneta; Majewski, Pawel; Jentsch, Holger; Eckert, Martin; Eick, Sigrun; Potempa, Jan; Zabel, Brian A.; Cichy, Joanna

2017-01-01

Periodontal inflammation is one of the most common chronic inflammatory conditions in humans. Despite recent advances in identifying and characterizing oral microbiota dysbiosis in the pathogenesis of gum disease, just how host factors maintain a healthy homeostatic oral microbial community or prevent the development of a pathogenic oral microbiota remains poorly understood. An important determinant of microbiota fate is local antimicrobial proteins. Here, we report that chemoattractant protein chemerin, which we recently identified as a potent endogenous antimicrobial agent in body barriers such as the skin, is present in the oral cavity under homeostatic and inflammatory conditions. Chemerin and a chemerin-derived antimicrobial peptide are bactericidal against select bacteria strategically positioned in dental biofilm. Gingival crevicular samples from patients with gingivitis but not periodontitis contain abundant bioactive chemerin capable of inducing CMKLR1-dependent leukocyte migration. Gingipains secreted by the periodontopathogen P. gingivalis inactivate chemerin. Together, these data suggest that as an antimicrobial agent and leukocyte chemoattractant, chemerin likely contributes to antimicrobial immune defense in the oral cavity. PMID:28424689

Antimicrobial and Attractant Roles for Chemerin in the Oral Cavity during Inflammatory Gum Disease.

PubMed

Godlewska, Urszula; Brzoza, Piotr; Sroka, Aneta; Majewski, Pawel; Jentsch, Holger; Eckert, Martin; Eick, Sigrun; Potempa, Jan; Zabel, Brian A; Cichy, Joanna

2017-01-01

Periodontal inflammation is one of the most common chronic inflammatory conditions in humans. Despite recent advances in identifying and characterizing oral microbiota dysbiosis in the pathogenesis of gum disease, just how host factors maintain a healthy homeostatic oral microbial community or prevent the development of a pathogenic oral microbiota remains poorly understood. An important determinant of microbiota fate is local antimicrobial proteins. Here, we report that chemoattractant protein chemerin, which we recently identified as a potent endogenous antimicrobial agent in body barriers such as the skin, is present in the oral cavity under homeostatic and inflammatory conditions. Chemerin and a chemerin-derived antimicrobial peptide are bactericidal against select bacteria strategically positioned in dental biofilm. Gingival crevicular samples from patients with gingivitis but not periodontitis contain abundant bioactive chemerin capable of inducing CMKLR1-dependent leukocyte migration. Gingipains secreted by the periodontopathogen P. gingivalis inactivate chemerin. Together, these data suggest that as an antimicrobial agent and leukocyte chemoattractant, chemerin likely contributes to antimicrobial immune defense in the oral cavity.

Solvent exchange-induced in situ forming gel comprising ethyl cellulose-antimicrobial drugs.

PubMed

Phaechamud, Thawatchai; Mahadlek, Jongjan

2015-10-15

Solvent-exchanged in situ forming gel is a drug delivery system which is in sol form before administration. When it contacts with the body fluid, then the water miscible organic solvent dissipates and water penetrates into the system, leading the polymer precipitation as in situ gel at the site of injection. The aim of this research was to study the parameters affecting the gel properties, drug release and antimicrobial activities of the in situ forming gels prepared from ethyl cellulose (EC) dissolved in N-methyl pyrrolidone (NMP) to deliver the antimicrobial agents (doxycycline hyclate, metronidazole and benzyl peroxide) for periodontitis treatment. The gel appearance, pH, viscosity, rheology, syringeability, gel formation, rate of water diffusion into the gels, in vitro degradation, drug release behavior and antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans and Porphyrommonas gingivalis were determined. Increasing the amount of EC increased the viscosity of system while still exhibiting Newtonian flow and increased the work of syringeability whereas decreased the releasing of drug. The system transformed into the rigid gel formation after being injected into the simulated gingival crevicular fluid. The developed systems containing 5% w/w antimicrobial agent showed the antimicrobial activities against all test bacteria. Thus the developed solvent exchange-induced in situ forming gels comprising EC-antimicrobial drugs exhibited potential use for periodontitis treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Antimicrobial resistance of Shigella spp. from humans in Shanghai, China, 2004-2011.

PubMed

Zhang, Jianmin; Jin, Huiming; Hu, Jiayu; Yuan, Zhengan; Shi, Weimin; Yang, Xiaowei; Xu, Xuebin; Meng, Jianghong

2014-03-01

A retrospective study conducted on patients with diarrhea in Shanghai, China from 2004-2011, indicated that of 77,600 samples collected, 1,635 (2.1%) tested positive for Shigella. Species isolated included S. sonnei (1,066, 65.1%), S. flexneri (569, 34.7%), and S. boydii (3, 0.2%). Most of the Shigella isolates were found to be resistant to streptomycin (98.7%), trimethoprim (98.0%), ampicillin (92.1%), and nalidixic acid (91.7%). Additionally, many isolates were resistant to tetracycline (86.9%), trimethoprim + sulfamethoxazole (80.1%), sulfisoxazole (76.8%) and gentamicin (55.5%). Approximately 80% of the isolates were resistant to at least eight antimicrobial agents, 14% to at least ten antimicrobials tested and 10 isolates to fourteen antimicrobials, including sulfonamides, fluoroquinolones, tetracyclines, aminoglycosides and β-lactamases. Importantly, co-resistance to fluoroquinolones and the third- and fourth-generation cephalosporins was also identified. The high levels of resistance to antimicrobial agents commonly used in clinical medicine presents a great challenge to treating patients with shigellosis. Copyright © 2014 Elsevier Inc. All rights reserved.

Fibrous Filter to Protect Building Environments from Polluting Agents: A Review

NASA Astrophysics Data System (ADS)

Chavhan, Md. Vaseem; Mukhopadhyay, Arunangshu

2016-04-01

This paper discusses the use of fibrous filter to protect the building environments from air born polluting agents and especially of concern chemical, biological and radiological agents. Air-filtration includes removal of particulate from air and toxic gases from air. In air filtration, particulate which are mostly biological and radioactive types of agents can be removed by using mechanical and electrostatic filters. Some biological agents, which cannot be removed by air filtration alone, special techniques like antimicrobial finish, UV germicides, coated filters etc. are required. Biocide agent can be added into the fibre itself by grafting reaction to impart antimicrobial activity. Chemical agents like toxic gases can be removed by integrating adsorbents and sorbents in filters or by fibre modifications. It is also possible to impart catalytic conversion properties into the fibre to remove volatile gasous. Radioactive agents can be removed by particulate filter if present in the form of aerosol or by gas cleaning by the use of specific fibre impregnate.

Lipopolysaccharide induces amyloid formation of antimicrobial peptide HAL-2.

PubMed

Wang, Jiarong; Li, Yan; Wang, Xiaoming; Chen, Wei; Sun, Hongbin; Wang, Junfeng

2014-11-01

Lipopolysaccharide (LPS), the important component of the outer membrane of Gram-negative bacteria, contributes to the integrity of the outer membrane and protects the cell against bactericidal agents, including antimicrobial peptides. However, the mechanisms of interaction between antimicrobial peptides and LPS are not clearly understood. Halictines-2 (HAL-2), one of the novel antimicrobial peptides, was isolated from the venom of the eusocial bee Halictus sexcinctus. HAL-2 has exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria and even against cancer cells. Here, we studied the interactions between HAL-2 and LPS to elucidate the antibacterial mechanism of HAL-2 in vitro. Our results show that HAL-2 adopts a significant degree of β-strand structure in the presence of LPS. LPS is capable of inducing HAL-2 amyloid formation, which may play a vital role in its antimicrobial activity. Copyright © 2014 Elsevier B.V. All rights reserved.

Machine learning: novel bioinformatics approaches for combating antimicrobial resistance.

PubMed

Macesic, Nenad; Polubriaginof, Fernanda; Tatonetti, Nicholas P

2017-12-01

Antimicrobial resistance (AMR) is a threat to global health and new approaches to combating AMR are needed. Use of machine learning in addressing AMR is in its infancy but has made promising steps. We reviewed the current literature on the use of machine learning for studying bacterial AMR. The advent of large-scale data sets provided by next-generation sequencing and electronic health records make applying machine learning to the study and treatment of AMR possible. To date, it has been used for antimicrobial susceptibility genotype/phenotype prediction, development of AMR clinical decision rules, novel antimicrobial agent discovery and antimicrobial therapy optimization. Application of machine learning to studying AMR is feasible but remains limited. Implementation of machine learning in clinical settings faces barriers to uptake with concerns regarding model interpretability and data quality.Future applications of machine learning to AMR are likely to be laboratory-based, such as antimicrobial susceptibility phenotype prediction.

Alpha-Melanocyte Stimulating Hormone: An Emerging Anti-Inflammatory Antimicrobial Peptide

PubMed Central

Singh, Madhuri; Mukhopadhyay, Kasturi

2014-01-01

The alpha-melanocyte stimulating hormone (α-MSH) is a neuropeptide belonging to the melanocortin family. It is well known for its anti-inflammatory and antipyretic effects and shares several characteristics with antimicrobial peptides (AMPs). There have been some recent reports about the direct antimicrobial activity of α-MSH against various microbes belonging to both fungal and bacterial pathogens. Similar to α-MSH's anti-inflammatory properties, its C-terminal residues also exhibit antimicrobial activity parallel to that of the entire peptide. This review is focused on the current findings regarding the direct antimicrobial potential and immunomodulatory mechanism of α-MSH and its C-terminal fragments, with particular emphasis on the prospects of α-MSH based peptides as a strong anti-infective agent. PMID:25140322

Antimicrobial hydrogels: promising materials for medical application

PubMed Central

Yang, Kerong; Han, Qing; Chen, Bingpeng; Zheng, Yuhao; Zhang, Kesong; Li, Qiang; Wang, Jincheng

2018-01-01

The rapid emergence of antibiotic resistance in pathogenic microbes is becoming an imminent global public health problem. Local application of antibiotics might be a solution. In local application, materials need to act as the drug delivery system. The drug delivery system should be biodegradable and prolonged antibacterial effect should be provided to satisfy clinical demand. Hydrogel is a promising material for local antibacterial application. Hydrogel refers to a kind of biomaterial synthesized by a water-soluble natural polymer or a synthesized polymer, which turns into gel according to the change in different signals such as temperature, ionic strength, pH, ultraviolet exposure etc. Because of its high hydrophilicity, unique three-dimensional network, fine biocompatibility and cell adhesion, hydrogel is one of the suitable biomaterials for drug delivery in antimicrobial areas. In this review, studies from the past 5 years were reviewed, and several types of antimicrobial hydrogels according to different ingredients, different preparations, different antimicrobial mechanisms, different antimicrobial agents they contained and different applications, were summarized. The hydrogels loaded with metal nanoparticles as a potential method to solve antibiotic resistance were highlighted. Finally, future prospects of development and application of antimicrobial hydrogels are suggested. PMID:29695904

Enhanced antimicrobial activity in biosynthesized ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Kumari, Niraj; Kumari, Priti; Jha, Anal K.; Prasad, K.

2018-05-01

Biological synthesis of different metallic and/or oxide nanoparticles and their applications especially in agriculture and biomedical sciences are gaining prominence nowadays due to their handy and reproducible synthetic protocols which are cost-effective and eco-friendly. In this work, green synthesis of zinc oxide nanoparticles (ZnO NPs) using the alcoholic extract of Azadirachta indica as a reducing and stabilizing agent has been presented. Formation of ZnO NPs was confirmed by X-ray diffraction, scanning and transmission electron microscopy techniques. The phytochemicals responsible for nano-transformation were principally alkaloids, flavanoids, terpenoids, tannins and organic acids present in the Azadirachta indica leaves. The synthesized ZnO NPs were used for antimicrobial assays by disc diffusion method against Staphylococcus aureus and Candida albicans. Results showed that ZnO NPs may act as antimicrobial agent especially against skin infections.

Topical Antimicrobials for Burn Infections – An Update

PubMed Central

Sevgi, Mert; Toklu, Ani; Vecchio, Daniela; Hamblin, Michael R

2014-01-01

The relentless rise in antibiotic resistance among pathogenic bacteria and fungi, coupled with the high susceptibility of burn wounds to infection, and the difficulty of systemically administered antibiotics to reach damaged tissue, taken together have made the development of novel topical antimicrobials for burn infections a fertile area of innovation for researchers and companies. We previously covered the existing patent literature in this area in 2010, but the notable progress made since then, has highlighted the need for an update to bring the reader up to date on recent developments. New patents in the areas of topically applied antibiotics and agents that can potentiate the action of existing antibiotics may extend their useful lifetime. Developments have also been made in biofilm-disrupting agents. Antimicrobial peptides are nature’s way for many life forms to defend themselves against attack by pathogens. Silver has long been known to be a highly active antimicrobial but new inorganic metal derivatives based on bismuth, copper and gallium have emerged. Halogens such as chlorine and iodine can be delivered by novel technologies. A variety of topically applied antimicrobials include chitosan preparations, usnic acid, ceragenins and XF porphyrins. Natural product derived antimicrobials such as tannins and essential oils have also been studied. Novel techniques to deliver reactive oxygen species and nitric oxide in situ have been developed. Light-mediated techniques include photodynamic therapy, ultraviolet irradiation, blue light, low-level laser therapy and titania photocatalysis. Passive immunotherapy employs antibodies against pathogens and their virulence factors. Finally an interesting new area uses therapeutic microorganisms such as phages, probiotic bacteria and protozoa to combat infections. PMID:24215506

Pheno- and genotypic analysis of antimicrobial resistance properties of Yersinia ruckeri from fish.

PubMed

Huang, Yidan; Michael, Geovana Brenner; Becker, Roswitha; Kaspar, Heike; Mankertz, Joachim; Schwarz, Stefan; Runge, Martin; Steinhagen, Dieter

2014-07-16

Enteric red-mouth disease, caused by Yersinia ruckeri, is an important disease in rainbow trout aquaculture. Antimicrobial agents are frequently used in aquaculture, thereby causing a selective pressure on bacteria from aquatic organisms under which they may develop resistance to antimicrobial agents. In this study, the distribution of minimal inhibitory concentrations (MICs) of antimicrobial agents for 83 clinical and non-clinical epidemiologically unrelated Y. ruckeri isolates from north west Germany was determined. Antimicrobial susceptibility was conducted by broth microdilution at 22 ± 2°C for 24, 28 and 48 h. Incubation for 24h at 22 ± 2°C appeared to be suitable for susceptibility testing of Y. ruckeri. In contrast to other antimicrobial agents tested, enrofloxacin and nalidixic acid showed a bimodal distribution of MICs, with one subpopulation showing lower MICs for enrofloxacin (0.008-0.015 μg/mL) and nalidixic acid (0.25-0.5 μg/mL) and another subpopulation exhibiting elevated MICs of 0.06-0.25 and 8-64 μg/mL, respectively. Isolates showing elevated MICs revealed single amino acid substitutions in the quinolone resistance-determining region (QRDR) of the GyrA protein at positions 83 (Ser83-Arg or -Ile) or 87 (Asn87-Tyr), which raised the MIC values 8- to 32-fold for enrofloxacin or 32- to 128-fold for nalidixic acid. An isolate showing elevated MICs for sulfonamides and trimethoprim harbored a ∼ 8.9 kb plasmid, which carried the genes sul2, strB and a dfrA14 gene cassette integrated into the strA gene. These observations showed that Y. ruckeri isolates were able to develop mutations that reduce their susceptibility to (fluoro)quinolones and to acquire plasmid-borne resistance genes. Copyright © 2013 Elsevier B.V. All rights reserved.

Antimicrobial formulary management: a case study in a teaching hospital.

PubMed

Wright, D B

1991-01-01

The role of the formulary system for effective cost containment is becoming increasingly important. With antimicrobial agents taking up a large proportion of most pharmaceutical budgets, this group of agents is an obvious target for cost reduction. The responsible interchange of selected antimicrobial agents offers a promising method to achieve this goal. The Pharmacy and Therapeutics Committee at Henry Ford Hospital implemented the formulary replacement of cefoxitin with cefotetan on a cost basis after the agents were evaluated and considered to be therapeutically equivalent. Drug usage guidelines were developed to implement this change. Educational materials were distributed to the medical staff, and lectures on the appropriate use of cefotetan were given to the house staff. On implementation, all orders written for cefoxitin were automatically changed to cefotetan in the appropriate dosage. After the first 12 months of cefotetan usage no unanticipated problems with treatment failures or adverse effects were noted. Based on analysis of cefotetan use for the first year, a savings of +4F229,811 was achieved with this interchange.

Characteristics of antimicrobial studies registered in the USA through ClinicalTrials.Gov

PubMed Central

Stockmann, Chris; Sherwin, Catherine M.T.; Ampofo, Krow; Hersh, Adam L.; Pavia, Andrew T.; Byington, Carrie L.; Ward, Robert M.; Spigarelli, Michael G.

2013-01-01

Increasing rates of antimicrobial-resistant infections and the dwindling pipeline of new agents necessitate judicious, evidence-based antimicrobial prescribing. Clinical trials represent a vital resource for establishing evidence of safety and efficacy, which are crucial to guiding antimicrobial treatment decisions. The objective of this study was to comprehensively evaluate the characteristics of antimicrobial research studies registered in ClinicalTrials.gov. Primary outcome measures, funding sources, inclusion criteria and the reporting of study results were evaluated for 16 055 antimicrobial studies registered in ClinicalTrials.gov as of mid 2012. Interventional studies accounted for 93% of registered antimicrobial studies. Clinical trials of drugs (82%) and biologics (9%) were most common. Antibacterial, antiviral and antifungal studies accounted for 43%, 41% and 16% of drug trials, respectively. Among interventional drug trials, 73% featured randomised allocation to study arms and 71% included measures of safety and/or efficacy as primary endpoints. Children were eligible for enrolment in 26% of studies. Among the studies, 60% were sponsored primarily by non-profit organisations, 30% by industry and 10% by the federal government. Only 7% of studies reported results; however, 71% of these were sponsored primarily by industry. Antimicrobial studies commonly incorporated elements of high-quality trial design, including randomisation and safety/efficacy endpoints. Publication of study results and updating of ClinicalTrials.gov should be encouraged for all studies, with particular attention paid to research sponsored by non-profit organisations and governmental agencies. Leveraging the application of these data to guide the careful selection of antimicrobial agents will be essential to preserve their utility for years to come. PMID:23726436

Current Trends of Using Antimicrobial Drugs in the ICU at a Tertiary Level Teaching Hospital in Mymensingh.

PubMed

Saha, S K; Shaha, K C; Haque, M F; Khatun, S; Akhter, S M; Akhter, H

2016-10-01

The aim of the present study was to investigate the current trends of using antimicrobial drugs in the ICU at a tertiary level teaching hospital in Mymensingh. The study of prescribing patterns seeks to monitor, evaluate and suggest modifications in clinicians prescribing habits so as to make medical care rational. It was an observational type of descriptive study, conducted in the Mymensingh medical college hospital, Mymensingh, during the study period of June 2016 to September 2016.The study was approved by the institutional ethical committee. Most patients in the ICU belonged to the older age group >60 years. Male patients were more than the female patients in ICU. Average duration of stay in ICU was 4.35 days. Admissions in ICU were common due to respiratory system related diseases and the present study showed that 31.68% of the reported cases belong to the respiratory system. Average number of drugs per prescription was 6.46. Average number of anti-microbial drugs per prescription was 1.38. Cephalosporin group and individually ceftriaxone was the most frequently prescribed antimicrobial group and agent respectively in the ICU. Most commonly used antimicrobial combination was Cephalosporin and Metronidazole (43.33%) followed by Carbapenem (Meropenem) and Metronidazole (13.33%). Most antimicrobial agents were prescribed without bacteriological culture and sensivity testing evidence. There is a need for motivating the physicians to prescribe antimicrobial agents with supportive bacteriological evidences.

Effects of subinhibitory concentrations of antimicrobial agents on Escherichia coli O157:H7 Shiga toxin release and role of the SOS response.

PubMed

Nassar, Farah J; Rahal, Elias A; Sabra, Ahmad; Matar, Ghassan M

2013-09-01

Treatment of Escherichia coli O157:H7 by certain antimicrobial agents often exacerbates the patient's condition by increasing either the release of preformed Shiga toxins (Stx) upon cell lysis or their production through the SOS response-triggered induction of Stx-producing prophages. Recommended subinhibitory concentrations (sub-MICs) of azithromycin (AZI), gentamicin (GEN), imipenem (IMI), and rifampicin (RIF) were evaluated in comparison to norfloxacin (NOR), an SOS-inducer, to assess the role of the SOS response in Stx release. Relative expression of recA (SOS-inducer), Q (late antitermination gene of Stx-producing prophage), stx1, and stx2 genes was assessed at two sub-MICs of the antimicrobials for two different strains of E. coli O157:H7 using reverse transcription-real-time polymerase chain reaction. Both strains at the two sub-MICs were also subjected to Western blotting for LexA protein expression and to reverse passive latex agglutination for Stx detection. For both strains at both sub-MICs, NOR and AZI caused SOS-induced Stx production (high recA, Q, and stx2 gene expression and high Stx2 production), so they should be avoided in E. coli O157:H7 treatment; however, sub-MICs of RIF and IMI induced Stx2 production in an SOS-independent manner except for one strain at the first twofold dilution below MIC of RIF where Stx2 production decreased. Moreover, GEN caused somewhat increased Stx2 production due to its mode of action rather than any effect on gene expression. The choice of antimicrobial therapy should rely on the antimicrobial mode of action, its concentration, and on the nature of the strain.

Antibacterial Potential of an Antimicrobial Agent Inspired by Peroxidase-Catalyzed Systems

PubMed Central

Tonoyan, Lilit; Fleming, Gerard T. A.; Mc Cay, Paul H.; Friel, Ruairi; O'Flaherty, Vincent

2017-01-01

Antibiotic resistance is an increasingly serious threat to global health. Consequently, the development of non-antibiotic based therapies and disinfectants, which avoid induction of resistance, or cross-resistance, is of high priority. We report the synthesis of a biocidal complex, which is produced by the reaction between ionic oxidizable salts—iodide and thiocyanate—in the presence of hydrogen peroxide as an oxidation source. The reaction generates bactericidal reactive oxygen and iodine species. In this study, we report that the iodo-thiocyanate complex (ITC) is an effective bactericidal agent with activity against planktonic and biofilm cells of Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and methicillin-resistant S. aureus) bacteria. The minimum bactericidal concentrations and the minimum biofilm eradication concentrations of the biocidal composite were in the range of 7.8–31.3 and 31.3–250 μg ml−1, respectively. As a result, the complex was capable to cause a rapid cell death of planktonic test cultures at between 0.5 and 2 h, and complete eradication of dual and mono-species biofilms between 30 s and 10 min. Furthermore, the test bacteria, including a MRSA strain, exposed to the cocktail failed to develop resistance after serial passages. The antimicrobial activity of the ITC appears to derive from the combinational effect of the powerful species capable of oxidizing the essential biomolecules of bacteria. The use of this composition may provide an effective and efficient method for killing potential pathogens, as well as for disinfecting and removing biofilm contamination. PMID:28512449

Antimicrobial resistance in zoonotic nontyphoidal Salmonella: an alarming trend?

PubMed

Michael, G B; Schwarz, S

2016-12-01

Zoonotic bacteria of the genus Salmonella have acquired various antimicrobial resistance properties over the years. The corresponding resistance genes are commonly located on plasmids, transposons, gene cassettes, or variants of the Salmonella Genomic Islands SGI1 and SGI2. Human infections by nontyphoidal Salmonella isolates mainly result from ingestion of contaminated food. The two predominantly found Salmonella enterica subsp. enterica serovars in the USA and in Europe are S. Enteritidis and S. Typhimurium. Many other nontyphoidal Salmonella serovars have been implicated in foodborne Salmonella outbreaks. Summary reports of the antimicrobial susceptibility patterns of nontyphoidal Salmonella isolates over time suggest a moderate to low level of antimicrobial resistance and multidrug-resistance. However, serovar-specific analyses showed in part a steady state, a continuous decline, or a recent increase in resistance to certain antimicrobial agents. Resistance to critically important antimicrobial agents, e.g. third-generation cephalosporins and (fluoro)quinolones is part of many monitoring programmes and the corresponding results confirm that extended-spectrum β-lactamases are still rarely found in nontyphoidal Salmonella serovars, whereas resistance to (fluoro)quinolones is prevalent at variable frequencies among different serovars from humans and animals in different countries. Although it is likely that nontyphoidal Salmonella isolates from animals represent a reservoir for resistance determinants, it is mostly unknown where and when Salmonella isolates acquired resistance properties and which exchange processes have happened since then. Copyright © 2016 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Current state of a dual behaviour of antimicrobial peptides-Therapeutic agents and promising delivery vectors.

PubMed

Piotrowska, Urszula; Sobczak, Marcin; Oledzka, Ewa

2017-12-01

Micro-organism resistance is an important challenge in modern medicine due to the global uncontrolled use of antibiotics. Natural and synthetic antimicrobial peptides (AMPs) symbolize a new family of antibiotics, which have stimulated research and clinical interest as new therapeutic options for infections. They represent one of the most promising antimicrobial substances, due to their broad spectrum of biological activity, against bacteria, fungi, protozoa, viruses, yeast and even tumour cells. Besides, being antimicrobial, AMPs have been shown to bind and neutralize bacterial endotoxins, as well as possess immunomodulatory, anti-inflammatory, wound-healing, angiogenic and antitumour properties. In contrast to conventional antibiotics, which have very defined and specific molecular targets, host cationic peptides show varying, complex and very rapid mechanisms of actions that make it difficult to form an effective antimicrobial defence. Importantly, AMPs display their antimicrobial activity at micromolar concentrations or less. To do this, many peptide-based drugs are commercially available for the treatment of numerous diseases, such as hepatitis C, myeloma, skin infections and diabetes. Herein, we present an overview of the general mechanism of AMPs action, along with recent developments regarding carriers of AMPs and their potential applications in medical fields. © 2017 John Wiley & Sons A/S.

Optimization of four types of antimicrobial agents to increase the inhibitory ability of marine Arthrobacter oxydans KQ11 dextranase mouthwash

NASA Astrophysics Data System (ADS)

Ren, Wei; Wang, Shujun; Lü, Mingsheng; Wang, Xiaobei; Fang, Yaowei; Jiao, Yuliang; Hu, Jianen

2016-03-01

We adopted the response surface methodology using single factor and orthogonal experiments to optimize four types of antimicrobial agents that could inhibit biofilm formation by Streptococcus mutans, which is commonly found in the human oral cavity and causes tooth decay. The objective was to improve the function of marine Arthrobacter oxydans KQ11 dextranase mouthwash (designed and developed by our laboratory). The experiment was conducted in a three-level, four-variable central composite design to determine the best combination of ZnSO4, lysozyme, citric acid and chitosan. The optimized antibacterial agents were 2.16 g/L ZnSO4, 14 g/L lysozyme, 4.5 g/L citric acid and 5 g/L chitosan. The biofilm formation inhibition reached 84.49%. In addition, microscopic observation of the biofilm was performed using scanning electron microscopy and confocal laser scanning microscopy. The optimized formula was tested in marine dextranase Arthrobacter oxydans KQ11 mouthwash and enhanced the inhibition of S. mutans. This work may be promoted for the design and development of future marine dextranase oral care products.

Light insensitive silver(I) cyanoximates as antimicrobial agents for indwelling medical devices.

PubMed

Gerasimchuk, Nikolay; Gamian, Andrzej; Glover, Garrett; Szponar, Bogumila

2010-11-01

Ten silver(I) cyanoximates of AgL composition (L = NC-C(NO)-R, where R is electron withdrawing groups: -CN, -C(O)NR(2), -C(O)R' (alkyl), -C(O)OEt, 2-heteroaryl fragments such as 2-pyridyl, 2-benzimidazolyl, 2-benzoxazolyl, 2-benzthiazolyl) were synthesized and characterized using spectroscopic methods and X-ray analysis. Crystal structures of four complexes were determined and revealed the formation of two-dimensional (2D) coordination polymers of different complexity in which anions exhibit bridging or combined chelate and bridging binding modes. In these compounds, anions are in the nitroso form. All studied AgL complexes are sparingly soluble in water and are thermally stable to 150 °C. Synthesized compounds demonstrated remarkable insensitivity toward visible light and UV-radiation, which was explained based on their polymeric structures with multiple covalent bonds between bridging cyanoxime ligands and Ag(I) centers. All 10 silver(I) cyanoximates were tested in vitro on the subject of their antimicrobial activity against both Gram-positive and Gram-negative microorganisms such as Escherichia coli, Klebsiella pneumoniae, Proteus sp., Pseudomonas aeruginosa, Enterococcus hirae, Streptococcus mutans, Staphylococcus aureus, and Mycobacterium fortuitum as well as against Candida albicans in solutions, and in the solid state as pressed pellets and dried filter paper disks presoaked with solutions of AgL in DMF. Results showed pronounced antimicrobial activity for all investigated complexes. A combination of five factors: (1) light insensitivity, (2) poor water solubility, (3) high thermal stability, (4) lack of toxicity of organic ligands, and (5) in vitro antimicrobial activity allows development of silver(I) cyanoximates for medical applications. These include antimicrobial additives to acrylate glue, cured by UV-radiation, used in introduction of prosthetic joints and dental implants, and prevention of biofilm formation on several types of indwelling medical

The Impact of an Antimicrobial Utilization Program on Antimicrobial Use at a Large Teaching Hospital: A Randomized Controlled Trial

PubMed Central

Camins, Bernard C.; King, Mark D.; Wells, Jane B.; Googe, Heidi L.; Patel, Manish; Kourbatova, Ekaterina V.; Blumberg, Henry M.

2009-01-01

Background Multidisciplinary antimicrobial utilization teams (AUT) have been proposed as a mechanism for improving antimicrobial use, but data on their efficacy remain limited. Objective To determine the impact of an AUT on antimicrobial use at a teaching hospital. Design Randomized controlled intervention trial. Setting A 953-bed public university-affiliated urban teaching hospital. Patients Patients who were prescribed selected antimicrobial agents (piperacillin-tazobactam, levofloxacin, or vancomycin) by internal medicine ward teams. Intervention Twelve internal medicine teams were randomized monthly: 6 teams to intervention group (academic detailing by the AUT), and 6 teams to a control group given indication-based guidelines for prescription of broad spectrum antimicrobials (standard of care) during a 10-month study period. Measurements Proportion of appropriate empiric, definitive (therapeutic), and end antimicrobial (overall) usage. Results A total of 784 new prescriptions of piperacillin-tazobactam, levofloxacin, and vancomycin were reviewed. The proportion of appropriate antimicrobial prescriptions written by the intervention teams was significantly higher than prescribed by the control teams: 82% vs. 73% for empiric (RR=1.14, 95% CI 1.04–1.24), 82% vs. 43% for definitive (RR=1.89, 95% CI 1.53–2.33), and 94% vs. 70% for end antimicrobial usage (RR=1.34, 95% CI 1.25–1.43). In a multivariate analysis, teams that received feedback from the AUT alone (aRR=1.37, 95% CI 1.27–1.48) or from both the AUT and the ID consult service (aRR=2.28, 95% CI 1.64–3.19) were significantly more likely to prescribe end antimicrobial usage appropriately compared to control teams. Conclusions A multidisciplinary AUT which provides feedback to prescribing physicians was an effective method in improving antimicrobial use. PMID:19712032

Antimicrobials in animal production: usage and practices among livestock farmers in Oyo and Kaduna States of Nigeria.

PubMed

Ojo, Olufemi Ernest; Fabusoro, Eniola; Majasan, Ademola Adetokunbo; Dipeolu, Morenike Atinuke

2016-01-01

Antimicrobials have proven to be important for sustainable livestock production by their use as growth promoters and in the control of animal infections. However, injudicious use of antimicrobials could accelerate the emergence and spread of resistant bacterial strains with attendant socioeconomic and public health issues. This work assessed antimicrobial usage in animal production with emphasis on usage and practices by livestock producers in Oyo and Kaduna States of Nigeria. Data on antimicrobial usage were collected through interviews, questionnaire and focus group discussions. Four hundred and fifty-four farmers in 11 communities within 11 Local Government Areas of Oyo and Kaduna States of Nigeria were sampled in a multi-stage sampling procedure. The study showed that antimicrobial agents were widely distributed, readily accessible and commonly used in animal production. Fluoroquinolones and other critically important antimicrobials for human medicine were widely used in animals as prophylactics. Potentially harmful antimicrobials including furazolidones and chloramphenicol already banned for use in humans and animals were freely marketed and used in livestock production. Most of the respondents believed that veterinarians should be responsible for the administration of antimicrobials to animals, but in practice, they buy and administer antimicrobials without consulting veterinary professionals. It was observed that the ready availability of antimicrobial agents promoted the use of antimicrobials in livestock production and may encourage non-adherence to hygienic principles and management laxity in farm operations. The non-involvement of veterinary professionals and laboratory investigations in disease diagnosis prior to antimicrobial use could lead to improper usage that contribute to the development of antimicrobial resistance in bacterial strains. Responsible antimicrobial stewardship and strict regulations are vital to prolonging the benefits derivable from

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.

Mechanisms of Antimicrobial Resistance in ESKAPE Pathogens

PubMed Central

Santajit, Sirijan; Indrawattana, Nitaya

2016-01-01

The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are the leading cause of nosocomial infections throughout the world. Most of them are multidrug resistant isolates, which is one of the greatest challenges in clinical practice. Multidrug resistance is amongst the top three threats to global public health and is usually caused by excessive drug usage or prescription, inappropriate use of antimicrobials, and substandard pharmaceuticals. Understanding the resistance mechanisms of these bacteria is crucial for the development of novel antimicrobial agents or other alternative tools to combat these public health challenges. Greater mechanistic understanding would also aid in the prediction of underlying or even unknown mechanisms of resistance, which could be applied to other emerging multidrug resistant pathogens. In this review, we summarize the known antimicrobial resistance mechanisms of ESKAPE pathogens. PMID:27274985

Mechanisms of Antimicrobial Resistance in ESKAPE Pathogens.

PubMed

Santajit, Sirijan; Indrawattana, Nitaya

2016-01-01

The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are the leading cause of nosocomial infections throughout the world. Most of them are multidrug resistant isolates, which is one of the greatest challenges in clinical practice. Multidrug resistance is amongst the top three threats to global public health and is usually caused by excessive drug usage or prescription, inappropriate use of antimicrobials, and substandard pharmaceuticals. Understanding the resistance mechanisms of these bacteria is crucial for the development of novel antimicrobial agents or other alternative tools to combat these public health challenges. Greater mechanistic understanding would also aid in the prediction of underlying or even unknown mechanisms of resistance, which could be applied to other emerging multidrug resistant pathogens. In this review, we summarize the known antimicrobial resistance mechanisms of ESKAPE pathogens.

Antimicrobial activity and phytochemical characterization of Carya illinoensis.

PubMed

Bottari, Nathieli Bianchin; Lopes, Leonardo Quintana Soares; Pizzuti, Kauana; Filippi Dos Santos Alves, Camilla; Corrêa, Marcos Saldanha; Bolzan, Leandro Perger; Zago, Adriana; de Almeida Vaucher, Rodrigo; Boligon, Aline Augusti; Giongo, Janice Luehring; Baldissera, Matheus Dellaméa; Santos, Roberto Christ Vianna

2017-03-01

Carya illinoensis is a widespread species, belonging to the Juglandaceae family, commonly known as Pecan. Popularly, the leaves have been used in the treatment of smoking as a hypoglycemic, cleansing, astringent, keratolytic, antioxidant, and antimicrobial agent. The following research aimed to identify for the first time the phytochemical compounds present in the leaves of C. illinoensis and carry out the determination of antimicrobial activity of aqueous and ethanolic extracts. The antimicrobial activity was tested against 20 microorganisms by determining the minimum inhibitory concentration (MIC). Phenolic acids (gallic acid and ellagic acid), flavonoids (rutin), and tannins (catechins and epicatechins) were identified by HPLC-DAD and may be partially responsible for the antimicrobial activity against Gram-positive, Gram-negative, and yeast. The results showed MIC values between 25 mg/mL and 0.78 mg/mL. The extracts were also able to inhibit the production of germ tubes by Candida albicans. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antimicrobial drug use in dermatology in a teaching hospital in western Nepal.

PubMed

Sarkar, C; Das, B; Sripathi, H

2002-05-01

Medical audit is supposed to oversee, monitor and analyse standards of medical treatment at all levels of the healthcare delivery system. This study was undertaken to monitor the prescribing of antimicrobial drugs for patients seeking treatment in the dermatology outpatient department of the Manipal Teaching Hospital in Nepal. A total of 292 dermatology prescriptions of patients attending the dermatology OPD were collected between July 2000 and June 2001. Prescriptions for antimicrobial agents were separated from the total prescriptions collected, and evaluated. There were more female patients (58.2%) than male (41.8%) in our study; most were in the 21-40 year age group. The commonest cutaneous infections were acne (15.8%) followed by fungal infections (14.8%). Of the 292 prescriptions audited, 149 contained antimicrobial agents, constituting 36% of the total number of drugs prescribed. Of 256 antimicrobials prescribed, 63% were topical and 37% systemic; 5% were generic, 29% were from the essential drug list of Nepal, and 15% were fixed-dose combinations. Most of the patients received one or two antimicrobials, 50% of which were antibacterials and 40% antifungals. Though the selection of antimicrobial drugs used in dermatology was largely rational, anomalies were observed, and these issues were discussed with clinicians in relation to various aspects of drug use. The results indicate there is scope for improving prescribing habits. A periodic audit of drug prescribing is desirable in rationalising prescribing practice.

Improving the water solubility and antimicrobial activity of silymarin by nanoencapsulation.

PubMed

Lee, Ji-Soo; Hong, Da Young; Kim, Eun Suh; Lee, Hyeon Gyu

2017-06-01

The aims of this study were to improve the water solubility and antimicrobial activity of milk thistle silymarin by nanoencapsulation and to assess the functions of silymarin nanoparticle-containing film as an antimicrobial food-packaging agent. Silymarin nanoparticles were prepared using water-soluble chitosan (WCS) and poly-γ-glutamic acid (γ-PGA). As the WCS and silymarin concentrations increased, particle size and polydispersity index (PDI) significantly increased. Nanoencapsulation significantly improved the water solubility of silymarin 7.7-fold. Antimicrobial activity of silymarin was effectively improved when silymarin was entrapped within the nanocapsule compared to when it was not entrapped. Films incorporating silymarin nanoparticles had better antimicrobial activity than films incorporating free silymarin. The results suggest that silymarin nanoparticles have applications in antimicrobial food additives and food packing. Copyright © 2017 Elsevier B.V. All rights reserved.

New antimicrobial peptides against foodborne pathogens: From in silico design to experimental evidence.

PubMed

Palmieri, Gianna; Balestrieri, Marco; Proroga, Yolande T R; Falcigno, Lucia; Facchiano, Angelo; Riccio, Alessia; Capuano, Federico; Marrone, Raffaele; Neglia, Gianluca; Anastasio, Aniello

2016-11-15

Recently there has been growing interest in the discovery of new antimicrobial agents to increase safety and shelf-life of food products. Here, we developed an innovative approach by introducing the concept that mitochondrial targeting peptides (MTP) can interact and disrupt bacterial membranes, acting as antimicrobial agents. As proof-of-principle, we used a multidisciplinary strategy by combining in silico predictions, docking simulations and antimicrobial assays, to identify two peptides, MTP1 and MTP2, which were structurally and functionally characterized. Both compounds appeared effective against Listeria monocytogenes, one of the most important foodborne pathogens. Specifically, a significant bactericidal activity was evidenced with EC50 values of 16.8±1.2μM for MTP1 and 109±7.0μM for MTP2. Finally, NMR structure determinations suggested that MTP1 would be oriented into the membrane bilayer, while the molecular shape of MTP2 could indicate porin-mediated antimicrobial mechanisms, as predicted using molecular docking analysis. Therefore, MTPs represent alternative sources to design new potential bio-preservatives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antimicrobial activity of silver nanoparticles impregnated wound dressing

NASA Astrophysics Data System (ADS)

Shinde, V. V.; Jadhav, P. R.; Patil, P. S.

2013-06-01

In this work, silver nanoparticles were synthesized by simple wet chemical reduction method. The silver nitrate was reduced by Sodium borohydride used as reducing agent and Poly (vinyl pyrrolidone) (PVP) as stabilizing agent. The formation of silver nanoparticles was evaluated by UV-visible spectroscope and transmission electron microscope (TEM). Absorption spectrum consist two plasmon peaks at 410 and 668 nm revels the formation of anisotropic nanoparticles confirmed by TEM. The formation of silver nanoparticles was also evidenced by dynamic light scattering (DLS) study. DLS showed polydisperse silver nanoparticles with hydrodynamic size 32 nm. Protecting mechanism of PVP was manifested by FT-Raman study. Silver nanoparticles were impregnated into wound dressing by sonochemical method. The Kirby-Bauer disc diffusion methods were used for antimicrobial susceptibility testing. The antimicrobial activity of the samples has been tested against gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus.

Antimicrobial preservative use in parenteral products: past and present.

PubMed

Meyer, Brian K; Ni, Alex; Hu, Binghua; Shi, Li

2007-12-01

The following review provides a comprehensive summary of antimicrobial preservatives that are commonly used in licensed parenteral products to date. The information reviewed includes the general properties of the preservatives, the doses and frequency of their use, the classes of the preserved products (peptide, protein, vaccine, and small molecule products), the interactions with other formulation components, and the criteria commonly used for their selection in parental product formulations. It was revealed that phenol and benzyl alcohol are the two most common antimicrobial preservatives used in peptide and protein products, while phenoxyethanol is the most frequently used preservative in vaccines. Benzyl alcohol or a combination of methylparaben and propylparaben are generally found in small molecule parenteral formulations. The key criteria for antimicrobial preservative selection are the preservative's dose, antimicrobial functionality, and effect on the active ingredient. Additionally, the use of spectroscopic techniques (circular dicroism (CD) and fluorescence) and differential scanning calorimetry (DSC) were identified as common techniques used in evaluating an antimicrobial preservative for its impact on the conformational stability of peptide, protein, and vaccine antigens. The future use of preservatives is also discussed, including antimicrobial agents such as peptides, and regulatory requirements for antimicrobial effectiveness testing. (c) 2007 Wiley-Liss, Inc.

Antimicrobial activity of ceftaroline and other anti-infective agents against microbial pathogens recovered from the surgical intensive care patient population: a prevalence analysis.

PubMed

Edmiston, Charles E; Krepel, Candace J; Leaper, David; Ledeboer, Nathan A; Mackey, Tami-Lea; Graham, Mary Beth; Lee, Cheong; Rossi, Peter J; Brown, Kellie R; Lewis, Brian D; Seabrook, Gary R

2014-12-01

Ceftaroline is a new parenteral cephalosporin agent with excellent activity against methicillin-sensitive (MSSA) and resistant strains of Staphylococcus aureus (MRSA). Critically ill surgical patients are susceptible to infection, often by multi-drug-resistant pathogens. The activity of ceftaroline against such pathogens has not been described. Three hundred thirty-five consecutive microbial isolates were collected from surgical wounds or abscesses, respiratory, urine, and blood cultures from patients in the surgical intensive care unit (SICU) of a major tertiary medical center. Using Clinical and Laboratory Standards Institute (CLSI) standard methodology and published breakpoints, all aerobic, facultative anaerobic isolates were tested against ceftaroline and selected comparative antimicrobial agents. All staphylococcal isolates were susceptible to ceftaroline at a breakpoint of ≤1.0 mcg/mL. In addition, ceftaroline exhibited excellent activity against all streptococcal clinical isolates and non-ESBL-producing strains of Enterobacteriaceae (93.5%) recovered from SICU patients. Ceftaroline was inactive against ESBL-producing Enterobacteriaceae, Pseudomonas aeruginosa, vancomycin-resistant enterococci, and selective gram-negative anaerobic bacteria. At present, ceftaroline is the only cephalosporin agent that is active against community and healthcare-associated MRSA. Further studies are needed to validate the benefit of this novel broad-spectrum anti-infective agent for the treatment of susceptible serious infections in the SICU patient population.

Biological evaluation and molecular docking of some chromenyl-derivatives as potential antimicrobial agents.

PubMed

Ionuţ, Ioana; Vodnar, Dan Cristian; Oniga, Ilioara; Oniga, Ovidiu; Tiperciuc, Brînduşa; Tamaian, Radu

2016-01-01

Various thiosemicarbazones (TSCs) and their heterocyclic thiadiazolines (TDZ) possess important biological effects. In addition, chromenyl derivatives exhibit a wide range of pharmacological activities. Based on these findings and as a continuation of our research on nitrogen and sulfur containing compounds, we investigated a series of previously reported chromenyl-TSCs (1a-j) and chromenyl-TDZs (2a-j) for their in vitro antimicrobial activities against two bacterial and four fungal strains. MIC and MBC/MFC (µg/mL) values of these compounds were evaluated and compared to those of Spectinomycin, Moxifloxacin and Fluconazole, used as reference drugs. For a better understanding of the drug-receptor interactions, all the compounds were further subjected to molecular docking against four targets that were chosen based on the specific mechanism of action of the reference drugs used in the antimicrobial screening. All compounds tested showed equal or higher antibacterial/antifungal activities relative to the used reference drugs. In silico studies (molecular docking) revealed that all the investigated compounds showed good binding energies towards four receptor protein targets and supported their antimicrobial properties.

Synthesis, lipophilicity and antimicrobial activity evaluation of some new thiazolyl-oxadiazolines

PubMed Central

STOICA, CRISTINA IOANA; IONUȚ, IOANA; PÎRNĂU, ADRIAN; POP, CARMEN; ROTAR, ANCUȚA; VLASE, LAURIAN; ONIGA, SMARANDA; ONIGA, OVIDIU

2015-01-01

Background and aims Synthesis of new potential antimicrobial agents and evaluation of their lipophilicity. Methods Ten new thiazolyl-oxadiazoline derivatives were synthesized and their structures were validated by 1H-NMR and mass spectrometry. The lipophilicity of the compounds was evaluated using the principal component analysis (PCA) method. The necessary data for applying this method were obtained by reverse-phase thin-layer chromatography (RP-TLC). The antimicrobial activities were tested in vitro against four bacterial strains and one fungal strain. Results The lipophilicity varied with the structure but could not be correlated with the antimicrobial activity, since this was modest. Conclusions We have synthesized ten new heterocyclic compounds. After their physical and chemical characterization, we determined their lipophilicity and screened their antimicrobial activity. PMID:26733751

Identification of didecyldimethylammonium salts and salicylic acid as antimicrobial compounds in commercial fermented radish kimchi.

PubMed

Li, Jing; Chaytor, Jennifer L; Findlay, Brandon; McMullen, Lynn M; Smith, David C; Vederas, John C

2015-03-25

Daikon radish (Raphanus sativus) fermented with lactic acid bacteria, especially Leuconostoc or Lactobacillus spp., can be used to make kimchi, a traditional Korean fermented vegetable. Commercial Leuconostoc/radish root ferment filtrates are claimed to have broad spectrum antimicrobial activity. Leuconostoc kimchii fermentation products are patented as preservatives for cosmetics, and certain strains of this organism are reported to produce antimicrobial peptides (bacteriocins). We examined the antimicrobial agents in commercial Leuconostoc/radish root ferment filtrates. Both activity-guided fractionation with Amberlite XAD-16 and direct extraction with ethyl acetate gave salicylic acid as the primary agent with activity against Gram-negative bacteria. Further analysis of the ethyl acetate extract revealed that a didecyldimethylammonium salt was responsible for the Gram-positive activity. The structures of these compounds were confirmed by a combination of (1)H- and (13)C NMR, high-performance liquid chromatography, high-resolution mass spectrometry, and tandem mass spectrometry analyses. Radiocarbon dating indicates that neither compound is a fermentation product. No antimicrobial peptides were detected.

Characterization of antimicrobial resistant Escherichia coli isolated from processed bison carcasses.

PubMed

Li, Q; Sherwood, J S; Logue, C M

2007-12-01

To determine the phenotypic and genotypic antimicrobial susceptibility profiles of Escherichia coli from bison carcasses. The antimicrobial resistance of 138 E. coli isolates recovered from processed bison carcasses was determined by using the National Antimicrobial Resistance Monitoring System panels, polymerase chain reaction assays, plasmid analysis and conjugation studies. Resistance to 14 of the 16 antimicrobials was observed. Twenty-three (16.7%) isolates displayed resistance to at least one antimicrobial agent. The most prevalent resistances were to tetracycline (13.0%), sulfamethoxazole (7.9%) and streptomycin (5.8%). No resistance was observed to amikacin and ciprofloxacin. Further analysis of 23 antimicrobial-resistant E. coli isolates showed the presence of resistance genes corresponding to their phenotypic profiles. Results of conjugation studies carried out showed most isolates tested were able to transfer their resistance to recipients. This study indicated that multidrug-resistant E. coli isolates are present in bison. However, the resistance rate is lower than that reported in other meat species. The beneficial effects of antimicrobial-free feeding practice in bison may be promoting a reduction in the prevalence of antimicrobial resistance in commensal flora of bison.

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

Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis.

PubMed

Brouwer, Matthijs C; Tunkel, Allan R; van de Beek, Diederik

2010-07-01

The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease.

Antimicrobial Susceptibility Patterns of Brachyspira Species Isolated in Taiwan.

PubMed

Yeh, Jih-Ching; Lo, Dan-Yuan; Chang, Shao-Kuang; Kuo, Hung-Chih

2018-03-13

Some members of the Brachyspira genus cause diseases such as swine dysentery (SD) and porcine intestinal (or colonic) spirochetosis. Severe economic losses are caused by decreased feed intake and increased feed conversion ratio, as well as costs associated with treatment and death. A loss of clinical efficacy of some antimicrobial agents authorized for treating SD has been observed in many countries. The aim of this study was to analyze the antimicrobial susceptibility of Brachyspira isolated from Taiwan and to investigate the mechanism of decreased susceptibility to macrolides. A total of 55 Brachyspira isolates obtained from the grower-finisher period were evaluated in this study. These isolates included B. hyodysenteriae (n = 37), B. murdochii (n = 11), B. pilosicoli (n = 5), B. intermedia (n = 1), and B. innocens (n = 1). Antimicrobial susceptibility testing was performed to examine 12 selected antimicrobial agents. The results showed that the 50% and 90% minimum inhibitory concentration (MIC) values of the tested macrolides were all >256 μg/ml. The MIC 50 of lincomycin, tiamulin, carbadox, olaquindox, ampicillin, amoxicillin, doxycycline, oxytetracycline, and gentamicin were 32, 1, ≤0.125, ≤0.125, 0.5, 0.25, 2, 2, and 2 μg/ml. The genetic basis of the decreased susceptibility to tylosin and lincomycin in Brachyspira spp. was investigated and the results showed a possible connection to the mutations at position A2058 and G2032 of the 23S rRNA gene. These findings demonstrated that, in Taiwan, there may be a decrease in susceptibility of Brachyspira spp. to antimicrobials commonly used for the treatment of SD.

Antimicrobial susceptibility, serotypes and genotypes of Pasteurella multocida isolates associated with swine pneumonia in Taiwan.

PubMed

Yeh, Jih-Ching; Lo, Dan-Yuan; Chang, Shao-Kuang; Chou, Chi-Chung; Kuo, Hung-Chih

2017-09-21

Pasteurella multocida (PM) can cause progressive atrophic rhinitis and suppurative bronchopneumonia in pigs. The present study performed antimicrobial susceptibility testing and serotype and genotype identification on the 62 PM strains isolated from the lungs of diseased pigs with respiratory symptoms. Antimicrobial susceptibility testing examined 13 antimicrobial agents (amoxicillin, cefazolin, doxycycline, flumequine, enrofloxacin, florfenicol, kanamycin, lincomycin, Linco-Spectin (lincomycin and spectinomycin), erythromycin, tylosin, tilmicosin and tiamulin). Antimicrobial resistance ratios were over 40% in all of the antimicrobial agents except for cefazolin. The highest levels of resistance (100%) were found for kanamycin, erythromycin and tylosin. The majority of isolated strains was serotype D:L6 (n=35) followed by A:L3 (n=17). Comparison of the antimicrobial resistance levels between the two serotypes showed that the antimicrobial resistance rates were higher in D:L6 than in A:L3 for all the tested antimicrobials except for tylosin and tilmicosin. For PM with erm (B), erm (T) or erm (42), the results showed no significant difference compared with non-resistance gene strains in phenotype. Pulsed-field gel electrophoresis genotyping using Apa I restriction digestion of the genomic DNA demonstrated that there were 17 distinct clusters with a similarity of 85% or more, and the genotyping result was similar to that of serotyping. The results of the present study demonstrated that the PM isolated from diseased pigs in Taiwan was resistant to multiple antimicrobials, and the distribution of antimicrobial resistance was associated with pulsotype and serotype. © British Veterinary Association (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Antimicrobial activity of sodium hypochlorite in endodontics.

PubMed

Mohammadi, Zahed; Shalavi, Sousan

2013-01-01

One of the major objectives in endodontic therapy is to disinfect the entire root canal system. This goal may be achieved using mechanical instrumenation and chemical irrigation in conjunrction with medication of the root canal between treatment sessions. Microorganisms and their by-products are considered to be the major cause of pulpal and periradicular patholic. In order to reduce or eliminate bacteria and popular tissue remnants, the use of various irrigation solution during treatment have been suggested. Sodium hypochlorite (NaOCI), the most common irrigant, is an excellent nonspecific proteolytic and antimicrobial agent. The purpose of this paper is to review the antimicrobial activity of sodium hypochlorite.

Pharmacist-driven antimicrobial stewardship in intensive care units in East China: A multicenter prospective cohort study.

PubMed

Li, Zhongwang; Cheng, Baoli; Zhang, Kai; Xie, Guohao; Wang, Yan; Hou, Jinchao; Chu, Lihua; Zhao, Jialian; Xu, Zhijun; Lu, Zhongqiu; Sun, Huaqin; Zhang, Jian; Wang, Zhiyi; Wu, Haiya; Fang, Xiangming

2017-09-01

Antimicrobial stewardship programs, particularly pharmacist-driven programs, help reduce the unnecessary use of antimicrobial agents. The objective of this study was to assess the influence of pharmacist-driven antimicrobial stewardship on antimicrobial use, multidrug resistance, and patient outcomes in adult intensive care units in China. We conducted a multicenter prospective cohort study with a sample of 577 patients. A total of 353 patients were included under a pharmacist-driven antimicrobial stewardship program, whereas the remaining 224 patients served as controls. The primary outcome was all-cause hospital mortality. The pharmacist-driven antimicrobial stewardship program had a lower hospital mortality rate compared with the nonpharmacist program (19.3% vs 29.0%; P = .007). Furthermore, logistic regression analysis indicated that the pharmacist-driven program independently predicted hospital mortality (odds ratio, 0.57; 95% confidence interval, 0.36-0.91; P = .017) after adjustment. Meanwhile, this strategy had a lower rate of multidrug resistance (23.8% vs 31.7%; P = .037). Moreover, the strategy optimized antimicrobial use, such as having a shorter duration of empirical antimicrobial therapy (2.7 days; interquartile range [IQR], 1.7-4.6 vs 3.0; IQR, 1.9-6.2; P = .002) and accumulated duration of antimicrobial treatment (4.0; IQR, 2.0-7.0 vs 5.0; IQR, 3.0-9.5; P = .030). Pharmacist-driven antimicrobial stewardship in an intensive care unit decreased patient mortality and the emergence of multidrug resistance, and optimized antimicrobial agent use. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Antimicrobial resistance among Salmonella isolates from hospitals in Rome.

PubMed Central

Falbo, V.; Caprioli, A.; Mondello, F.; Cacace, M. L.; Luzi, S.; Greco, D.

1982-01-01

The susceptibility to antimicrobial agents of 569 salmonella isolated collected in 1977-8 from patients in hospitals in Rome was tested. Fifty-nine per cent of all isolates were resistant to one or more antimicrobials. Resistance was most common to sulphathiazole, tetracycline, streptomycin, whereas colistin, gentamicin, tobramycin, trimethoprim-sulphamethoxazole and nalidixic acid were the most active in vitro. Multiple resistance was most frequently found in strains of Salmonella wien and S. typhimurium (94% and 38% respectively). A significant change in the resistance pattern of S. wien was observed between 1977 and 1978, with a significant increase of susceptibility to some antimicrobials in 1978. Twenty-one R-plasmids transmissible to E. coli K12 were derived from 46 resistant strains of S. typhimurum. PMID:7061839