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Sample records for antimicrobial residues agents

  1. 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. PMID:11252480

  2. 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

  3. Investigational antimicrobial agents of 2013.

    PubMed

    Pucci, Michael J; Bush, Karen

    2013-10-01

    New antimicrobial agents are always needed to counteract the resistant pathogens that continue to be selected by current therapeutic regimens. This review provides a survey of known antimicrobial agents that were currently in clinical development in the fall of 2012 and spring of 2013. Data were collected from published literature primarily from 2010 to 2012, meeting abstracts (2011 to 2012), government websites, and company websites when appropriate. Compared to what was reported in previous surveys, a surprising number of new agents are currently in company pipelines, particularly in phase 3 clinical development. Familiar antibacterial classes of the quinolones, tetracyclines, oxazolidinones, glycopeptides, and cephalosporins are represented by entities with enhanced antimicrobial or pharmacological properties. More importantly, compounds of novel chemical structures targeting bacterial pathways not previously exploited are under development. Some of the most promising compounds include novel β-lactamase inhibitor combinations that target many multidrug-resistant Gram-negative bacteria, a critical medical need. Although new antimicrobial agents will continue to be needed to address increasing antibiotic resistance, there are novel agents in development to tackle at least some of the more worrisome pathogens in the current nosocomial setting. PMID:24092856

  4. Investigational Antimicrobial Agents of 2013

    PubMed Central

    Pucci, Michael J.

    2013-01-01

    SUMMARY New antimicrobial agents are always needed to counteract the resistant pathogens that continue to be selected by current therapeutic regimens. This review provides a survey of known antimicrobial agents that were currently in clinical development in the fall of 2012 and spring of 2013. Data were collected from published literature primarily from 2010 to 2012, meeting abstracts (2011 to 2012), government websites, and company websites when appropriate. Compared to what was reported in previous surveys, a surprising number of new agents are currently in company pipelines, particularly in phase 3 clinical development. Familiar antibacterial classes of the quinolones, tetracyclines, oxazolidinones, glycopeptides, and cephalosporins are represented by entities with enhanced antimicrobial or pharmacological properties. More importantly, compounds of novel chemical structures targeting bacterial pathways not previously exploited are under development. Some of the most promising compounds include novel β-lactamase inhibitor combinations that target many multidrug-resistant Gram-negative bacteria, a critical medical need. Although new antimicrobial agents will continue to be needed to address increasing antibiotic resistance, there are novel agents in development to tackle at least some of the more worrisome pathogens in the current nosocomial setting. PMID:24092856

  5. Scope of Hydrolysable Tannins as Possible Antimicrobial Agent.

    PubMed

    Ekambaram, Sanmuga Priya; Perumal, Senthamil Selvan; Balakrishnan, Ajay

    2016-07-01

    Hydrolysable tannins (HTs) are secondary metabolites from plants, which are roughly classified into gallotannins and ellagitannins having gallic acid and ellagic acid residues respectively attached to the hydroxyl group of glucose by ester linkage. The presence of hexahydroxydiphenoyl and nonahydroxyterphenoyl moieties is considered to render antimicrobial property to HTs. HTs also show considerable synergy with antibiotics. Nevertheless, they have low pharmacokinetic property. The present review presents the scope of HTs as future antimicrobial agent. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27062587

  6. 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

  7. Mechanisms of biofilm resistance to antimicrobial agents.

    PubMed

    Mah, T F; O'Toole, G A

    2001-01-01

    Biofilms are communities of microorganisms attached to a surface. It has become clear that biofilm-grown cells express properties distinct from planktonic cells, one of which is an increased resistance to antimicrobial agents. Recent work has indicated that slow growth and/or induction of an rpoS-mediated stress response could contribute to biocide resistance. The physical and/or chemical structure of exopolysaccharides or other aspects of biofilm architecture could also confer resistance by exclusion of biocides from the bacterial community. Finally, biofilm-grown bacteria might develop a biofilm-specific biocide-resistant phenotype. Owing to the heterogeneous nature of the biofilm, it is likely that there are multiple resistance mechanisms at work within a single community. Recent research has begun to shed light on how and why surface-attached microbial communities develop resistance to antimicrobial agents. PMID:11166241

  8. Repurposing celecoxib as a topical antimicrobial agent

    PubMed Central

    Thangamani, Shankar; Younis, Waleed; Seleem, Mohamed N.

    2015-01-01

    There is an urgent need for new antibiotics and alternative strategies to combat multidrug-resistant bacterial pathogens, which are a growing clinical issue. Repurposing existing approved drugs with known pharmacology and toxicology is an alternative strategy to accelerate antimicrobial research and development. In this study, we show that celecoxib, a marketed inhibitor of cyclooxygenase-2, exhibits broad-spectrum antimicrobial activity against Gram-positive pathogens from a variety of genera, including Staphylococcus, Streptococcus, Listeria, Bacillus, and Mycobacterium, but not against Gram-negative pathogens. However, celecoxib is active against all of the Gram-negative bacteria tested, including strains of, Acinetobacter, and Pseudomonas, when their intrinsic resistance is artificially compromised by outer membrane permeabilizing agents such as colistin. The effect of celecoxib on incorporation of radioactive precursors into macromolecules in Staphylococcus aureus was examined. The primary antimicrobial mechanism of action of celecoxib was the dose-dependent inhibition of RNA, DNA, and protein synthesis. Further, we demonstrate the in vivo efficacy of celecoxib in a methicillin-resistant S. aureus (MRSA) infected Caenorhabditis elegans whole animal model. Topical application of celecoxib (1 and 2%) significantly reduced the mean bacterial count in a mouse model of MRSA skin infection. Further, celecoxib decreased the levels of all inflammatory cytokines tested, including tumor necrosis factor-α, interleukin-6, interleukin-1 beta, and monocyte chemo attractant protein-1 in wounds caused by MRSA infection. Celecoxib also exhibited synergy with many conventional antimicrobials when tested against four clinical isolates of S. aureus. Collectively, these results demonstrate that celecoxib alone, or in combination with traditional antimicrobials, has a potential to use as a topical drug for the treatment of bacterial skin infections. PMID:26284040

  9. Discovery and development of new antimicrobial agents.

    PubMed Central

    Gootz, T D

    1990-01-01

    The unprecedented growth in the number of new antibiotics over the past two decades has been the result of extensive research efforts that have exploited the growing body of knowledge describing the interactions of antibiotics with their targets in bacterial cells. Information gained from one class of antimicrobial agents has often been used to advance the development of other classes. In the case of beta-lactams, information on structure-activity relationships gleaned from penicillins and cephalosporins was rapidly applied to the cephamycins, monobactams, penems, and carbapenems in order to discover broad-spectrum agents with markedly improved potency. These efforts have led to the introduction of many new antibiotics that demonstrate outstanding clinical efficacy and improved pharmacokinetics in humans. The current review discusses those factors that have influenced the rapid proliferation of new antimicrobial agents, including the discovery of new lead structures from natural products and the impact of bacterial resistance development in the clinical setting. The development process for a new antibiotic is discussed in detail, from the stage of early safety testing in animals through phase I, II, and III clinical trials. PMID:2404566

  10. In vitro susceptibility of Bordetella parapertussis to various antimicrobial agents.

    PubMed Central

    Watanabe, M; Haraguchi, Y

    1989-01-01

    The in vitro activity of 18 antimicrobial agents against 32 strains of Bordetella parapertussis isolated from whooping cough patients was studied. The most active antimicrobial agents were piperacillin and minocycline, followed (in descending order of activity) by moxalactam, erythromycin, cefoperazone, tetracycline, ampicillin, cefotaxime, chloramphenicol, josamycin, sulfamethoxazole, and nalidixic acid. Isolates were resistant to benzylpenicillin, cephalothin, cefatrizine, cefaclor, streptomycin, and cephalexin. PMID:2764546

  11. Antiendotoxin activity of cationic peptide antimicrobial agents.

    PubMed Central

    Gough, M; Hancock, R E; Kelly, N M

    1996-01-01

    The endotoxin from gram-negative bacteria consists of a molecule lipopolysaccharide (LPS) which can be shed by bacteria during antimicrobial therapy. A resulting syndrome, endotoxic shock, is a leading cause of death in the developed world. Thus, there is great interest in the development of antimicrobial agents which can reverse rather than promote sepsis, especially given the recent disappointing clinical performance of antiendotoxin therapies. We describe here two small cationic peptides, MBI-27 and MBI-28, which have both antiendotoxic and antibacterial activities in vitro and in vivo in animal models. We had previously demonstrated that these peptides bind to LPS with an affinity equivalent to that of polymyxin B. Consistent with this, the peptides blocked the ability of LPS and intact cells to induce the endotoxic shock mediator, tumor necrosis factor (TNF), upon incubation with the RAW 264.7 murine macrophage cell line. MBI-28 was equivalent to polymyxin B in its ability to block LPS induction of TNF by this cell line, even when added 60 min after the TNF stimulus. Furthermore, MBI-28 offered significant protection in a galactosamine-sensitized mouse model of lethal endotoxic shock. This protection correlated with the ability of MBI-28 to reduce LPS-induced circulating TNF by nearly 90% in this mouse model. Both MBI-27 and MBI-28 demonstrated antibacterial activity against gram-negative bacteria in vitro and in vivo against Pseudomonas aeruginosa infections in neutropenic mice. PMID:8945527

  12. Prodigiosin - A Multifaceted Escherichia coli Antimicrobial Agent.

    PubMed

    Danevčič, Tjaša; Borić Vezjak, Maja; Zorec, Maša; Stopar, David

    2016-01-01

    Despite a considerable interest in prodigiosin, the mechanism of its antibacterial activity is still poorly understood. In this work, Escherichia coli cells were treated with prodigiosin to determine its antimicrobial effect on bacterial physiology. The effect of prodigiosin was concentration dependent. In prodigiosin treated cells above MIC value no significant DNA damage or cytoplasmic membrane disintegration was observed. The outer membrane, however, becomes leaky. Cells had severely decreased respiration activity. In prodigiosin treated cells protein and RNA synthesis were inhibited, cells were elongated but could not divide. Pre-treatment with prodigiosin improved E. coli survival rate in media containing ampicillin, kanamycin and erythromycin but not phleomycin. The results suggest that prodigiosin acts as a bacteriostatic agent in E. coli cells. If prodigiosin was diluted, cells resumed growth. The results indicate that prodigiosin has distinct mode of antibacterial action in different bacteria. PMID:27612193

  13. Susceptibility of archaea to antimicrobial agents: applications to clinical microbiology.

    PubMed

    Khelaifia, S; Drancourt, M

    2012-09-01

    We herein review the state of knowledge regarding the in vitro and in vivo susceptibility of archaea to antimicrobial agents, including some new molecules. Indeed, some archaea colonizing the human microbiota have been implicated in diseases such as periodontopathy. Archaea are characterized by their broad-spectrum resistance to antimicrobial agents. In particular, their cell wall lacks peptidoglycan, making them resistant to antimicrobial agents interfering with peptidoglycan biosynthesis. Archaea are, however, susceptible to the protein synthesis inhibitor fusidic acid and imidazole derivatives. Also, squalamine, an antimicrobial agent acting on the cell wall, proved effective against human methanogenic archaea. In vitro susceptibility data could be used to design protocols for the decontamination of complex microbiota and the selective isolation of archaea in anaerobic culture. PMID:22748132

  14. Antimicrobial resistance of three species of Bacillus to thirty various antimicrobial agents.

    PubMed

    Moldenhauer, J E; Bass, S; Rubio, S L

    1996-01-01

    Three frequently used strains of Bacillus were tested using antimicrobial susceptibility test discs to determine their resistance to various antimicrobial drug agents. The organisms selected were B. subtilis ATCC 6633 (used for USP B and F tests), B. stearothermophilus ATCC 12980 (used as a biological indicator for steam sterilization) and B. coagulans ATCC 51232 (used as a biological indicator for steam sterilization). The results indicated that for the thirty antimicrobial drug agents tested, the only organisms which exhibited any resistance to these agents was B. subtilis, and it only showed resistance to two drugs (Aztreonam and Bacitracin). PMID:8973119

  15. Activity of 10 antimicrobial agents against intracellular Rhodococcus equi.

    PubMed

    Giguère, Steeve; Berghaus, Londa J; Lee, Elise A

    2015-08-01

    Studies with facultative intracellular bacterial pathogens have shown that evaluation of the bactericidal activity of antimicrobial agents against intracellular bacteria is more closely associated with in vivo efficacy than traditional in vitro susceptibility testing. The objective of this study was to determine the relative activity of 10 antimicrobial agents against intracellular Rhodococcus equi. Equine monocyte-derived macrophages were infected with virulent R. equi and exposed to erythromycin, clarithromycin, azithromycin, rifampin, ceftiofur, gentamicin, enrofloxacin, vancomycin, imipenem, or doxycycline at concentrations achievable in plasma at clinically recommended dosages in foals. The number of intracellular R. equi was determined 48h after infection by counting colony forming units (CFUs). The number of R. equi CFUs in untreated control wells were significantly higher than those of monolayers treated with antimicrobial agents. Numbers of R. equi were significantly lower in monolayers treated with enrofloxacin followed by those treated with gentamicin, and vancomycin, when compared to monolayers treated with other antimicrobial agents. Numbers of R. equi in monolayers treated with doxycycline were significantly higher than those of monolayers treated with other antimicrobial agents. Differences in R. equi CFUs between monolayers treated with other antimicrobial agents were not statistically significant. Enrofloxacin, gentamicin, and vancomycin are the most active drugs in equine monocyte-derived macrophages infected with R. equi. Additional studies will be needed to determine if these findings correlate with in vivo efficacy. PMID:26051479

  16. 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

  17. The Three Bacterial Lines of Defense against Antimicrobial Agents

    PubMed Central

    Zhou, Gang; Shi, Qing-Shan; Huang, Xiao-Mo; Xie, Xiao-Bao

    2015-01-01

    Antimicrobial agents target a range of extra- and/or intracellular loci from cytoplasmic wall to membrane, intracellular enzymes and genetic materials. Meanwhile, many resistance mechanisms employed by bacteria to counter antimicrobial agents have been found and reported in the past decades. Based on their spatially distinct sites of action and distribution of location, antimicrobial resistance mechanisms of bacteria were categorized into three groups, coined the three lines of bacterial defense in this review. The first line of defense is biofilms, which can be formed by most bacteria to overcome the action of antimicrobial agents. In addition, some other bacteria employ the second line of defense, the cell wall, cell membrane, and encased efflux pumps. When antimicrobial agents permeate the first two lines of defense and finally reach the cytoplasm, many bacteria will make use of the third line of defense, including alterations of intracellular materials and gene regulation to protect themselves from harm by bactericides. The presented three lines of defense theory will help us to understand the bacterial resistance mechanisms against antimicrobial agents and design efficient strategies to overcome these resistances. PMID:26370986

  18. Quaternized Chitosan as an Antimicrobial Agent: Antimicrobial Activity, Mechanism of Action and Biomedical Applications in Orthopedics

    PubMed Central

    Tan, Honglue; Ma, Rui; Lin, Chucheng; Liu, Ziwei; Tang, Tingting

    2013-01-01

    Chitosan (CS) is a linear polysaccharide with good biodegradability, biocompatibility and antimicrobial activity, which makes it potentially useful for biomedical applications, including an antimicrobial agent either alone or blended with other polymers. However, the poor solubility of CS in most solvents at neutral or high pH substantially limits its use. Quaternary ammonium CS, which was prepared by introducing a quaternary ammonium group on a dissociative hydroxyl group or amino group of the CS, exhibited improved water solubility and stronger antibacterial activity relative to CS over an entire range of pH values; thus, this quaternary modification increases the potential biomedical applications of CS in the field of anti-infection. This review discusses the current findings on the antimicrobial properties of quaternized CS synthesized using different methods and the mechanisms of its antimicrobial actions. The potential antimicrobial applications in the orthopedic field and perspectives regarding future studies in this field are also considered. PMID:23325051

  19. Recombinant expression, antimicrobial activity and mechanism of action of tritrpticin analogs containing fluoro-tryptophan residues.

    PubMed

    Arias, Mauricio; Hoffarth, Elesha R; Ishida, Hiroaki; Aramini, James M; Vogel, Hans J

    2016-05-01

    The increase in antibiotic-resistant bacterial infections has prompted significant academic research into new therapeutic agents targeted against these pathogens. Antimicrobial peptides (AMPs) appear as promising candidates, due their potent antimicrobial activity and their ubiquitous presence in almost all organisms. Tritrpticin is a member of this family of peptides and has been shown to exert a strong antimicrobial activity against several bacterial strains. Tritrpticin's main structural characteristic is the presence of three consecutive Trp residues at the center of the peptide. These residues play an important role in the activity of tritrpticin against Escherichia coli. In this work, a recombinant version of tritrpticin was produced in E. coli using calmodulin as a fusion protein expression tag to overcome the toxicity of the peptide. When used in combination with glyphosate, an inhibitor of the endogenous synthesis of aromatic amino acids, this expression system allowed for the incorporation of fluorinated Trp analogs at very high levels (>90%). The antimicrobial activity of the 4-, 5- and 6-fluoro-Trp-containing tritrpticins against E. coli was as strong as the activity of the native peptide. Similarly, the tritrpticin analogs exhibited comparable abilities to perturb and permeabilize synthetic lipid bilayers as well as the outer and inner membrane of E. coli. Furthermore, the use of 19F NMR spectroscopy established that each individual fluoro-Trp residue interacts differently with SDS micelles, supporting the idea that each Trp in the original tritrpticin plays a different role in the perturbing/permeabilizing activity of the peptide. Moreover, our work demonstrates that the use of fluoro-Trp in solvent perturbation 19F NMR experiments provides detailed site-specific information on the insertion of the Trp residues in biological membrane mimetics. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai

  20. 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

  1. Diphosphonium Ionic Liquids as Broad Spectrum Antimicrobial Agents

    PubMed Central

    O’Toole, George A.; Wathier, Michel; Zegans, Michael E.; Shanks, Robert M.Q.; Kowalski, Regis; Grinstaff, Mark W.

    2011-01-01

    Purpose One of the most disturbing trends in recent years is the growth of resistant strains of bacteria with the simultaneous dearth of new antimicrobial agents. Thus, new antimicrobial agents for use on the ocular surface are needed. Methods We synthesized a variety of ionic liquid compounds, which possess two positively charged phosphonium groups separated by ten methylene units in a “bola” type configuration. We tested these compounds for antimicrobial activity versus a variety of ocular pathogens, as well as their cytoxicity in vitro in a corneal cell line and in vivo in mice. Results The ionic liquid Di-Hex C10 demonstrated broad in vitro antimicrobial activity at the low micromolar concentrations versus Gram-negative and Gram-positive organisms, including methicillin-resistant Staphylococcus aureus strains, as well as ocular fungal pathogens. Treatment with Di-Hex C10 resulted in bacterial killing in as little as 15 minutes in vitro. Di-Hex C10 showed little cytotoxicity at 1 μM versus a corneal epithelial cell line or at 10 μM in a mouse corneal wound model. We also show that this bis-phosphonium ionic liquid structure is key, as a comparable mono phosphonium ionic liquid is cytotoxic to both bacteria and corneal epithelial cells. Conclusions Here we report the first use of dicationic bis-phosphonium ionic liquids as antimicrobial agents. Our data suggest that diphosphonium ionic liquids may represent a new class of broad-spectrum antimicrobial agents for use on the ocular surface. PMID:22236790

  2. Novel isoquinoline derivatives as antimicrobial agents.

    PubMed

    Galán, Abraham; Moreno, Laura; Párraga, Javier; Serrano, Ángel; Sanz, Ma Jesús; Cortes, Diego; Cabedo, Nuria

    2013-06-01

    The wide variety of potent biological activities of natural and synthetic isoquinoline alkaloids encouraged us to develop novel antimicrobial isoquinoline compounds. We synthesized a variety of differently functionalized 1-pentyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolines (THIQs), including dihydroisoquinolinium salts (2 and 5), methyl pentanoate-THIQ (6), 1-pentanol-THIQ (7), ester derivatives (8-15) and carbamate derivatives (16-23). We employed classic intramolecular Bischler-Napieralski cyclodehydration to generate the isoquinoline core. All the structures were characterized by nuclear magnetic resonance and mass spectrometry. The bactericide and fungicide activities were evaluated for all the synthesized compounds and structure-activity relationships were established. Many compounds exhibited high and broad-range bactericidal activity. Fluorophenylpropanoate ester 13 and the halogenated phenyl- (17, 18) and phenethyl carbamates (21, 22) exerted the most remarkable bactericidal activity. However, few compounds displayed antifungal activity against most of the fungi tested. Among them, chlorinated derivatives like chlorobenzoate and chlorophenylpropanoate esters (10 and 14, respectively) and chlorophenethyl carbamate 22, exhibited the greatest antifungal activity. PMID:23601815

  3. Current trends in antimicrobial agent research: chemo- and bioinformatics approaches.

    PubMed

    Hammami, Riadh; Fliss, Ismail

    2010-07-01

    Databases and chemo- and bioinformatics tools that contain genomic, proteomic and functional information have become indispensable for antimicrobial drug research. The combination of chemoinformatics tools, bioinformatics tools and relational databases provides means of analyzing, linking and comparing online search results. The development of computational tools feeds on a diversity of disciplines, including mathematics, statistics, computer science, information technology and molecular biology. The computational approach to antimicrobial agent discovery and design encompasses genomics, molecular simulation and dynamics, molecular docking, structural and/or functional class prediction, and quantitative structure-activity relationships. This article reviews progress in the development of computational methods, tools and databases used for organizing and extracting biological meaning from antimicrobial research. PMID:20546918

  4. Synthesis of riccardin D derivatives as potent antimicrobial agents.

    PubMed

    Sun, Bin; Zhang, Ming; Li, Ying; Hu, Qing-Wen; Zheng, Hong-Bo; Chang, Wen-Qiang; Lou, Hong-Xiang

    2016-08-01

    We describe the synthesis and biological evaluation of riccardin D derivatives, a novel class of antimicrobial molecules. Structural diversification of these derivatives was achieved by introducing hydroxy, methoxy, and bromine into the aromatic rings of riccardin D. The antimicrobial evaluation of these compounds was performed as in vitro assays against clinically isolated bacteria and fungi. The introduction of bromine atom into the arene B of riccardin D led to several strongly active antibacterial compounds with a MIC value ranging from 0.5 to 4μg/mL for Staphylococcus aureus, both methicillin-sensitive and -resistant strains. Antifungal tests found compound 34 was the most potent molecule with a MIC value of 2μg/mL against Candida albicans. This initial biological evaluation suggests that these novel molecules merit further investigation as potential antimicrobial agents. PMID:27297569

  5. Antimicrobial agents in orthopaedic surgery: Prophylaxis and treatment.

    PubMed

    Trampuz, Andrej; Zimmerli, Werner

    2006-01-01

    The pathogenesis of implant-associated infection involves interaction between the microorganisms (biofilm formation), the implant and the host. Despite improvement of perioperative prophylaxis, orthopaedic implants still remain highly susceptible to bacterial or fungal contamination, generally resulting in persistent implant-associated infection. Therefore, perioperative and life-long prevention of infection is important. For perioperative prophylaxis, a first- or second-generation cephalosporin is recommended, which should be administered between 60 and 30 minutes before incision. The duration of prophylaxis should not exceed 1 day. In centres with a low incidence of infection, a single dose is sufficient. Treatment of infections associated with orthopaedic devices usually requires appropriate surgical intervention combined with prolonged antimicrobial therapy. The choice of the antimicrobial regimen depends on the duration and pathogenesis of infection, stability of the implant, antimicrobial susceptibility of the pathogen and condition of the surrounding soft tissue. The role of rifampicin (rifampin), which has excellent activity on adherent staphylococci, in combination with beta-lactams, glycopeptides, fluoroquinolones, minocycline, cotrimoxazole or fusidic acid, in the treatment of staphylococcal infections is outlined. Increasing antimicrobial resistance requires the use of alternative agents, such as quinupristin/dalfopristin, linezolid and daptomycin, but results of clinical trials with these agents are limited. Also reviewed are potential new antimicrobial agents currently undergoing investigation, such as the novel oxazolidinone RWJ-416457, the new glycopeptide dalbavancin, the glycylcycline compound tigecycline, the new carbacephem BP-102 and novel rifamycin derivatives. Vaccination against Staphylococcus aureus with StaphVAX induced specific antibodies potentially preventing bacteraemia; however, there are no studies on efficacy in the prophylaxis of

  6. In vitro antimicrobial activity of peroxide-based bleaching agents.

    PubMed

    Napimoga, Marcelo Henrique; de Oliveira, Rogério; Reis, André Figueiredo; Gonçalves, Reginaldo Bruno; Giannini, Marcelo

    2007-06-01

    Antibacterial activity of 4 commercial bleaching agents (Day White, Colgate Platinum, Whiteness 10% and 16%) on 6 oral pathogens (Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, Candida albicans, Lactobacillus casei, and Lactobacillus acidophilus) and Staphylococcus aureus were evaluated. A chlorhexidine solution was used as a positive control, while distilled water was the negative control. Bleaching agents and control materials were inserted in sterilized stainless-steel cylinders that were positioned under inoculated agar plate (n = 4). After incubation according to the appropriate period of time for each microorganism, the inhibition zones were measured. Data were analyzed by 2-way analysis of variance and Tukey test (a = 0.05). All bleaching agents and the chlorhexidine solution produced antibacterial inhibition zones. Antimicrobial activity was dependent on peroxide-based bleaching agents. For most microorganisms evaluated, bleaching agents produced inhibition zones similar to or larger than that observed for chlorhexidine. C albicans, L casei, and L acidophilus were the most resistant microorganisms. PMID:17625621

  7. Antimicrobial susceptibility of Leptospira isolates from dogs and rats to 12 antimicrobial agents.

    PubMed

    Suepaul, S M; Carrington, C; Campbell, M; Borde, G; Adesiyun, A A

    2015-03-01

    This study determined the antimicrobial susceptibilities of 67 isolates of Leptospira from dogs (suspect canine cases: n=7 and stray dogs: n=6) and rodents (n=54) in Trinidad to 12 antimicrobial agents using broth microdilution and macrodilution techniques. Commonly used antimicrobial agents such as the penicillin G and ceftriaxone had relatively low minimal inhibitory concentrations (MICs) while doxycycline displayed a relatively higher value but was still considered to be effective. While imipenem was the most effective with low MIC values in vitro, sulphamethoxazole-trimethoprim had the highest i.e. least effective. Based on these results, the drugs commonly used in the treatment of leptospirosis (penicillin G, penicillin-streptomycin, doxycycline and ceftriaxone) in both humans and animals in Trinidad appear to have similar MICs and MBCs in vitro when compared with published reports. The serovar of Leptospira spp. and in most cases the origin of the isolates did not significantly (P>0.05) influence their susceptibilities to the antimicrobial agents tested. PMID:25801249

  8. 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

  9. 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. PMID:24915323

  10. Glycosylated Nanoparticles as Efficient Antimicrobial Delivery Agents.

    PubMed

    Eissa, Ahmed M; Abdulkarim, Ali; Sharples, Gary J; Cameron, Neil R

    2016-08-01

    Synthetic polymer nanoparticles that can be tailored through multivalent ligand display on the surface, while at the same time allowing encapsulation of desired bioactive molecules, are especially useful in providing a versatile and robust platform in the design of specific delivery vehicles for various purposes. Glycosylated nanoparticles (glyco-NPs) of a poly(n-butyl acrylate) (pBA) core and poly(N-2-(β-d-glucosyloxy)ethyl acrylamide) (p(NβGlcEAM)) or poly(N-2-(β-D-galactosyloxy)ethyl acrylamide) (p(NβGalEAM)) corona were prepared via nanoprecipitation in aqueous solutions of preformed amphiphilic glycopolymers. Well-defined block copolymers of (poly(pentafluorophenyl acrylate) (pPFPA) and pBA were first prepared by RAFT polymerization followed by postpolymerization functionalization with aminoethyl glycosides to yield p(NβGlcEAM-b-BA) and p(NβGalEAM-b-BA), which were then used to form glyco-NPs (glucosylated and galactosylated NPs, Glc-NPs and Gal-NPs, respectively). The glyco-NPs were characterized by dynamic light scattering (DLS) and TEM. Encapsulation and release of ampicillin, leading to nanoparticles that we have termed "glyconanobiotics", were studied. The ampicillin-loaded glyco-NPs were found to induce aggregation of Staphylococcus aureus and Escherichia coli and resulted in antibacterial activity approaching that of ampicillin itself. This glyconanobiotics strategy represents a potential new approach for the delivery of antibiotics close to the surface of bacteria by promoting bacterial aggregation. Defined release in the proximity of the bacterial envelope may thus enhance antibacterial efficiency and potentially reduce the quantities of agent required for potency. PMID:27434596

  11. Antimicrobial agents-associated with QT interval prolongation.

    PubMed

    Bril, Fernando; Gonzalez, Claudio Daniel; Di Girolamo, Guillermo

    2010-01-01

    QT interval prolongation is one of the most important causes of withdrawal of drugs from the market, due to its association with Torsades de Pointes (TdP), a potentially fatal arrhythmia. Although many antimicrobial drugs are capable of inducing this type of arrhythmia, the importance of this effect is usually underestimated. Macrolides, quinolones, azoles, pentamidine, protease inhibitors, antimalarial drugs and cotrimoxazole are the anti-infective agents more frequently associated with this adverse effect. Despite the fact that the risk of QT prolongation and TdP under single antimicrobial therapy is low, these drugs are so extensively used that sporadic cases of this arrhythmia are reported. Moreover, antimicrobial drugs are susceptible to pharmacokinetic and pharmacodynamic interactions with other drugs, which may increase the risk of this arrhythmia. Therefore, physicians must be familiar with not only the antimicrobial drugs capable of producing QT interval prolongation, but also their potential interactions. In addition, patient's specific risk factors of prolonging QT interval or producing TdP must be taken into account. This article reviews the role of anti-infective drugs in QT prolongation, focusing on QT prolongation mechanisms, potential drug interactions, and patients' predisposing factors to this arrhythmia. PMID:20210724

  12. Essential oil nanoemulsions as antimicrobial agents in food.

    PubMed

    Donsì, Francesco; Ferrari, Giovanna

    2016-09-10

    The crescent interest in the use of essential oils (EOs) as natural antimicrobials and preservatives in the food industry has been driven in the last years by the growing consumers' demand for natural products with improved microbial safety, and fresh-like organoleptic properties. Nanoemulsions efficiently contribute to support the use of EOs in foods by increasing their dispersibility in the food areas where microorganisms grow and proliferate, by reducing the impact on the quality attributes of the product, as well as by enhancing their antimicrobial activity. Understanding how nanoemulsions intervene on the mass transfer of EOs to the cell membrane and on the mechanism of antimicrobial action will support the engineering of more effective delivery systems and foster the application of EOs in real food systems. This review focuses on the enabling contribution of nanoemulsions to the use of EOs as natural preservative agents in food, (a) specifically addressing the formulation and fabrication of stable EO nanoemulsions, (b) critically analyzing the reported antimicrobial activity data, both in vitro and in product, to infer the impact of the delivery system on the mechanisms of action of EOs, as well as (c) discussing the regulatory issues associated with their use in food systems. PMID:27416793

  13. [Biofilm disclosing agents in complete denture: clinical and antimicrobial evaluation].

    PubMed

    Silva, Cláudia Helena Lovato da; Paranhos, Helena de Freitas Oliveira; Ito, Isabel Yoko

    2002-01-01

    This study evaluated the disclosing ability, removal facility and antimicrobial effect of biofilm disclosing agents applied on complete dentures. Disclosing ability was evaluated by means of the visual method. The solutions were applied on the internal surface of dentures. After being photographed, the dentures were brushed with denture-specific brush and dentifrice and photographed again. The obtained slides were projected on paper (10 X amplification) and the total and stained surfaces were outlined with graphite, cut off and weighed, in order to assess removal facility. The evaluation of antimicrobial effects was carried out by means of the method of diffusion in agar, and the results were obtained by measuring the length of the halos and rings. In terms of disclosing ability, the best solutions were 0.05% methylene blue, 5% erythrosin, 1% sodic fluorescein, Replak and 1% neutral red. One percent eosin, 1% sodic fluorescein and 5% erythrosin were the most easily removed solutions. One percent eosin, 5% erythrosin, 1% sodic fluorescein, 0.3% proflavine, Replak and 1% neutral red presented no antimicrobial effect. The solutions which presented the greatest disclosing ability and removal facility as well as absence of antimicrobial effect - which are essential requirements in the assessment of hygiene methods and guidance on oral health - were 1% eosin, 1% neutral red and 5% erythrosin. PMID:12386691

  14. Recent applications of liquid chromatography-mass spectrometry to residue analysis of antimicrobials in food of animal origin.

    PubMed

    Bogialli, Sara; Di Corcia, Antonio

    2009-10-01

    Residual antimicrobials in food constitute a risk to human health. Although epidemiological data on the real magnitude of their adverse effects are very scarce, they indicate that food could be an important vehicle for evolution and dissemination of antimicrobial-resistant bacteria. Public health agencies in many countries rely on detection by mass spectrometry (MS) for unambiguous identification of residues of antimicrobial agents in animal food products for human consumption. The introduction of relatively inexpensive and robust liquid chromatography (LC)-MS systems has given a strong impulse to the development of confirmatory methods for the above medicines in foodstuffs. The initial part of this review, after a brief introduction into the field of antimicrobials, is dedicated to the most important EU regulations and directives for control of residues of these substances in animal products. The main attention in this review is on the sample-treatment and MS detection systems in use today for analysing the most important classes of antimicrobials in various biological matrices (milk, animal tissues, eggs, and honey). As evidenced by this review, reversed-phase LC combined with tandem MS, usually triple-quadrupole MS (QqQMS), is currently the preferred technique in most residue analysis of a single-class of antimicrobials. A recently emerging analytical strategy is that of developing methods for detecting a large variety of veterinary drugs belonging to different classes, including pesticides (multi-class residue analysis). To do this, simple and generic extraction and separation techniques applicable to a broad range of compounds differing in physical and chemical properties have been adopted. Such methods are still based mainly on LC-QqQMS. Emerging alternative MS detection systems are time-of-flight MS, which provides accurate mass of the analyte(s), or Q-linear ion trap (IT) MS that eliminates some limitations of ITMS(n). PMID:19609510

  15. Residual antimicrobial effect of chlorhexidine digluconate and octenidine dihydrochloride on reconstructed human epidermis.

    PubMed

    Müller, G; Langer, J; Siebert, J; Kramer, A

    2014-01-01

    The objective of the present investigation was to examine the residual antimicrobial activity after a topical exposure of reconstructed human epidermis (RHE) to equimolar solutions of either chlorhexidine digluconate (CHG, 0.144% w/v) or octenidine dihydrochloride (OCT, 0.1% w/v) for 15 min. RHE-associated antiseptic agents were more effective on Staphylococcus aureus than on Pseudomonas aeruginosa. S. aureus was not detected after 24 h of contact, which demonstrated a microbicidal efficacy of greater than 5-log10 reduction. In contrast, P. aeruginosa was reduced by approximately 2 log10 at the same incubation time, which parallels the growth of the initial inoculum. This result could be interpreted either as a microbiostatic effect or as an adherence of P. aeruginosa to a low positively charged surface. Small amounts of CHG and OCT can penetrate the stratum corneum. Using these antiseptic agents, the viability of keratinocytes was reduced to 65-75% of that of the untreated RHE control following 24 h incubation in the presence of test microorganisms. With consideration of antimicrobial activity and cytotoxic effect, OCT corresponds better to a biocompatible antiseptic agent than CHG. PMID:23887383

  16. A synthetic peptide adhesion epitope as a novel antimicrobial agent.

    PubMed

    Kelly, C G; Younson, J S; Hikmat, B Y; Todryk, S M; Czisch, M; Haris, P I; Flindall, I R; Newby, C; Mallet, A I; Ma, J K; Lehner, T

    1999-01-01

    The earliest step in microbial infection is adherence by specific microbial adhesins to the mucosa of the oro-intestinal, nasorespiratory, or genitourinary tract. We inhibited binding of a cell surface adhesin of Streptococcus mutans to salivary receptors in vitro, as measured by surface plasmon resonance, using a synthetic peptide (p1025) corresponding to residues 1025-1044 of the adhesin. Two residues within p1025 that contribute to binding (Q1025, E1037) were identified by site-directed mutagenesis. In an in vivo human streptococcal adhesion model, direct application of p1025 to the teeth prevented recolonization of S. mutans but not Actinomyces, as compared with a control peptide or saline. This novel antimicrobial strategy, applying competitive peptide inhibitors of adhesion, may be used against other microorganisms in which adhesins mediate colonization of mucosal surfaces. PMID:9920267

  17. Coping with the rising tide of resistance to antimicrobial agents.

    PubMed

    Hunter, P A

    2001-06-01

    The 11th European Congress of Clinical Microbiology and Infectious Diseases was held in Istanbul, Turkey, from April 2nd to April 4th, 2001. The meeting was attended by approximately 4,500 people. Sessions were well attended and included a number of workshops, keynote lectures, symposia, free papers and posters. As at many chemotherapy meetings in recent years, a major topic was the continuing growth of resistance among all microbes to antimicrobial agents, and this is the topic highlighted in this report. PMID:12813593

  18. [Susceptibility of spore-forming butyric acid bacteria to antimicrobial agents].

    PubMed

    Kaneko, Naofumi; Nakayama, Tomohiro; Ichikawa, Nobuhiro

    2012-01-01

    Antimicrobial agents occasionally cause certain adverse effects, such as diarrhea and loose stool, by altering the composition of the intestinal flora. Antibiotic-resistant lactic acid bacteria are used to prevent these adverse effects. Although these bacteria are not resistant to several recently introduced antimicrobial agents, bacterial preparations are still sometimes prescribed concomitantly with these antimicrobial agents. In this study, we investigated whether the administration of the spore-forming butyric acid bacteria Clostridium butyricum improves the adverse clinical effects by preventing diarrhea. Inhibition of C. butyricum growth was observed with 17 of the 20 antimicrobial agents used. However, dilution of 11 of these 17 agents resulted in the regrowth of C. butyricum. These results suggest that C. butyricum may survive exposure to several antibiotic agents by forming spores. Further, a decrease in the antimicrobial agent concentration in the gastrointestinal tract permits the vegetative growth of C. butyricum, which functions as a probiotic. PMID:22790032

  19. Alanine-Scanning Mutational Analysis of Durancin GL Reveals Residues Important for Its Antimicrobial Activity.

    PubMed

    Ju, Xingrong; Chen, Xinquan; Du, Lihui; Wu, Xueyou; Liu, Fang; Yuan, Jian

    2015-07-22

    Durancin GL is a novel class IIa bacteriocin with 43 residues produced by Enterococcus durans 41D. This bacteriocin demonstrates narrow inhibition spectrum and potent antimicrobial activity against several Listeria monocytogenes strains, including nisin-resistant L. monocytogenes NR30. A systematic alanine-scanning mutational analysis with site-directed mutagenesis was performed to analyze durancin GL residues important for antimicrobial activity and specificity. Results showed that three mutations lost their antimicrobial activity, ten mutations demonstrated a decreased effect on the activity, and seven mutations exhibited relatively high activity. With regard to inhibitory spectrum, four mutants demonstrated a narrower antimicrobial spectrum than wild-type durancin GL. Another four mutants displayed a broader target cell spectrum and increased potency relative to wild-type durancin GL. These findings broaden our understanding of durancin GL residues important for its antimicrobial activity and contribute to future rational design of variants with increased potency. PMID:26168032

  20. Effects of treatment with antimicrobial agents on the human colonic microflora

    PubMed Central

    Rafii, Fatemeh; Sutherland, John B; Cerniglia, Carl E

    2008-01-01

    Antimicrobial agents are the most valuable means available for treating bacterial infections. However, the administration of therapeutic doses of antimicrobial agents to patients is a leading cause of disturbance of the normal gastrointestinal microflora. This disturbance results in diminishing the natural defense mechanisms provided by the colonic microbial ecosystem, making the host vulnerable to infection by commensal microorganisms or nosocomial pathogens. In this minireview, the impacts of antimicrobials, individually and in combinations, on the human colonic microflora are discussed. PMID:19337440

  1. New triazole and triazolothiadiazine derivatives as possible antimicrobial agents.

    PubMed

    Kaplancikli, Zafer Asim; Turan-Zitouni, Gülhan; Ozdemir, Ahmet; Revial, Gilbert

    2008-01-01

    Triazole and triazoles fused with six-membered ring systems are found to possess diverse applications in the fields of medicine, agriculture and industry. The new 1,2,4-triazole and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine derivatives were synthesized as novel antimicrobial agents. The reaction of 1H-indol-3-acetic acid with thiocarbohydrazide gave the 4-amino-3-mercapto-5-[(1H-indol-3-yl)methyl]-4H-1,2,4-triazole. The reaction of triazole with arylaldehydes in ethanol gave the 4-arylideneamino-3-mercapto-5-[(1H-indol-3-yl)methyl]-4H-1,2,4-triazoles (I). The 3-[(1H-indol-3-yl)methyl]-6-aryl-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines (II) were obtained by condensing triazole with phenacyl bromides in absolute ethanol . The chemical structures of the compounds were elucidated by IR, (1)H NMR and FAB(+)-MS spectral data. Their antimicrobial activities against Micrococcus luteus (NRLL B-4375), Bacillus cereus (NRRL B-3711), Proteus vulgaris (NRRL B-123), Salmonella typhimurium (NRRL B-4420), Staphylococcus aureus (NRRL B-767), Escherichia coli (NRRL B-3704), Candida albicans and Candida glabrata (isolates obtained from Osmangazi University, Faculty of Medicine) were investigated and significant activity was obtained. PMID:17499887

  2. Influence of topically applied antimicrobial agents on muscular microcirculation.

    PubMed

    Goertz, Ole; Hirsch, Tobias; Ring, Andrej; Steinau, Hans U; Daigeler, Adrien; Lehnhardt, Marcus; Homann, Heinz H

    2011-10-01

    Bacterial infections cause major complications in wound healing. Local antiseptics are used for daily wound care; however, their potential toxic effects on the vasculature have not yet been thoroughly investigated. The aim of this study was to assess the effects of antiseptics on microcirculation. Investigations were performed on a standardized cremaster muscle model on rats (n = 60). The arteriolar diameter and functional capillary density (FCD) were investigated using transillumination microscopy before and 60 and 120 minutes after application of each of the following antimicrobial agents: alcohol, hydrogen peroxide, imipenem, octenidine dihydrochloride, polyhexanide, and ethacridine lactate. Although polyhexanide caused a significant arteriolar dilatation (106.25 ± 3.23 vs. 88.54 ± 6.74 μm [baseline value]) and increase of FCD compared with baseline value (12.65 ± 0.82 vs. 9.10 ± 0.50 n/0.22 mm), alcohol led to a significant decrease of both parameters (90.63 ± 10.80 vs. 52.09 ± 7.69 and 5.35 ± 0.54 vs. 1.68 ± 0.48) and was the only agent that caused arteriolar thrombosis. The FCD also increased significantly after treatment with hydrogen peroxide (10.55 ± 0.33 vs. 12.30 ± 0.48) and octenidine (6.82 ± 0.63 vs. 12.32 ± 0.63). However, no positive effect on arteriolar diameter could be found. Ethacridine lactate and imipenem did not impact either parameter. In addition to reducing bacteria, an antiseptic should be nontoxic, especially to the microcirculation. Polyhexanide seems to have a positive influence on vessel diameter and capillary density, whereas alcohol reduces both parameters. If the antimicrobial efficacy is comparable, the antiseptic with less toxic effects should be chosen, especially in critically perfused wounds. PMID:21407057

  3. 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. PMID:27117429

  4. Detection limits of four antimicrobial residue screening tests for beta-lactams in goat's milk.

    PubMed

    Sierra, D; Sánchez, A; Contreras, A; Luengo, C; Corrales, J C; Morales, C T; de la Fe, C; Guirao, I; Gonzalo, C

    2009-08-01

    This study was conducted to compare the detection limits (DL) of several antibiotic residue screening tests with the maximum residue limits (MRL) authorized by the EU according to the guidance for the standardized evaluation of microbial inhibitor tests of the International Dairy Federation. Composite antibiotic-free milk samples from 30 primiparous Murciano-Granadina goats in good health condition were used to prepare test samples spiked with different concentrations of each antimicrobial. In total, 5,760 analytical determinations of 10 beta-lactam antibiotics (penicillin-G, ampicillin, amoxicillin, cloxacillin, oxacillin, dicloxacillin, cefadroxyl, cefalexin, cefoperazone, and cefuroxime) were performed using 4 antibiotic residue screening tests: the brilliant black reduction test BRT AiM (AiM-Analytik in Milch Produktions-und Vertriebs GmbH, München, Germany), Delvotest MCS (DSM Food Specialties, Delft, the Netherlands), Eclipse 100 (ZEU-Inmunotec SL, Zaragoza, Spain), and the Copan Milk Test (CMT; Copan Italia SpA, Brescia, Italy). For each method, we estimated the detection limits of the antimicrobial agents using a logistic regression model. Using the CMT and Delvotest on samples spiked with the 8 antibiotics for which MRL were available, DL were at or below the MRL. The BRT test provided DL at or below the MRL for all of the agents except cefalexin, whereas the Eclipse 100 method failed to detect 4 antibiotics (ampicillin, amoxicillin, cloxacillin, and cefoperazone) at MRL or below. Logistic regression-determined levels of agreement were highest for the CMT method (98.6 to 100%) and lowest for Eclipse 100 (66.3 to 100%). In general, agreement levels indicated good correlation between observed results and those predicted by logistic regression. The lowest b values (closely related to test sensitivity) were recorded for the cephalosporins (0.074 to 0.430) and highest for penicillin G, ampicillin, and amoxicillin (11.270 to 11.504). Delvotest and CMT best

  5. [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. PMID:17893761

  6. [Investigation of Aspergillus galactomannan levels in antimicrobial agents].

    PubMed

    Yücesoy, Mine; Ergon, M Cem

    2007-10-01

    The diagnosis of invasive aspergillosis which is a serious infection of immunocompromized patients, depends on the detection of Aspergillus galactomannan antigen in the serum by enzyme immunoassay (EIA) in routine laboratories. However, it has been previously reported that false positive results in Aspergillus galactomannan test may be obtained in the sera of patients sera receiving piperacillin-tazobactam (PIP-TAZ). The aim of this study was to investigate the presence and levels of Aspergillus galactomannan antigen in the content of PIP-TAZ and some other antimicrobial agents that are often used for the treatment of infections in immunocompromised patients. The level of galactomannan antigen was determined for PIP-TAZ, ampicillin-sulbactam, ampicillin, penicillin G, ceftriaxone, cefepime, imipenem, clarithromycin, ciprofloxacin, vancomycin, gentamicin, trimethoprim-sulfamethoxazole, ornidazole, fluconazole and amphotericin B, by a commercial EIA (Platelia Aspergillus EIA, Bio-Rad, France) kit. Galactomannan index (GI) was estimated with the ratio of absorbance values of antimicrobials to cut-off value and evaluated as positive when GI was found >0.5. Amongst the 15 antibiotics studied, the only positive result was detected for ampicillin with the highest index value (GI = 0.540), followed by PIP-TAZ with a relatively high value (GI = 0.235) even though it was not in the range of positivity. GI values have ranged from 0.011 to 0.188 for the other antibiotics. In conclusion, the use of especially ampicillin (and probably PIP-TAZ) therapy should be questioned in patients whose sera are being tested for Aspergillus galactomannan antigen by EIA in order to evaluate the positive results in terms of false positivities due to cross reactivity. PMID:18173075

  7. Controlling the release of peptide antimicrobial agents from surfaces.

    PubMed

    Shukla, Anita; Fleming, Kathleen E; Chuang, Helen F; Chau, Tanguy M; Loose, Christopher R; Stephanopoulos, Gregory N; Hammond, Paula T

    2010-03-01

    Medical conditions are often exacerbated by the onset of infection caused by hospital dwelling bacteria such as Staphylococcus aureus. Antibiotics taken orally or intravenously can require large and frequent doses, further contributing to the sharp rise in resistant bacteria observed over the past several decades. These existing antibiotics are also often ineffective in preventing biofilm formation, a common cause of medical device failure. Local delivery of new therapeutic agents that do not allow bacterial resistance to occur, such as antimicrobial peptides, could alleviate many of the problems associated with current antibacterial treatments. By taking advantage of the versatility of layer-by-layer assembly of polymer thin films, ponericin G1, an antimicrobial peptide known to be highly active against S. aureus, was incorporated into a hydrolytically degradable polyelectrolyte multilayer film. Several film architectures were examined to obtain various drug loadings that ranged from 20 to 150 microg/cm2. Release was observed over approximately ten days, with varying release profiles, including burst as well as linear release. Results indicated that film-released peptide did not suffer any loss in activity against S. aureus and was able to inhibit bacteria attachment, a necessary step in preventing biofilm formation. Additionally, all films were found to be biocompatible with the relevant wound healing cells, NIH 3T3 fibroblasts and human umbilical vein endothelial cells. These films provide the level of control over drug loading and release kinetics required in medically relevant applications including coatings for implant materials and bandages, while eliminating susceptibility to bacterial resistance. PMID:20004967

  8. Residual antimicrobial activity after canal irrigation with chlorhexidine.

    PubMed

    White, R R; Hays, G L; Janer, L R

    1997-04-01

    We previously reported that the in vitro antimicrobial activity of a 2.0% chlorhexidine endodontic irrigant was equivalent to that of 5.25% sodium hypochlorite. The purpose of this study was to determine if chlorhexidine irrigants could instill substantive antimicrobial activity in instrumented root canals in vitro. Human teeth were instrumented using 2.0% or 0.12% chlorhexidine as irrigants. After instrumentation, the root canals were filled with sterile water, and samples of the root canal fluid were absorbed with paper points at 6, 12, 24, 48, and 72 h after treatment. The paper points were assayed for antimicrobial activity by placing them on agar plate surfaces inoculated with Streptococcus mutans and measuring zones of inhibition. Antimicrobial activity was present in all 2.0% chlorhexidine-treated teeth throughout the 72-h testing period and in most teeth, in relatively lower concentrations, for 6 to 24 h after irrigation with 0.12% chlorhexidine. These results indicate that chlorhexidine instills substantive antimicrobial activity when used as an endodontic irrigant. PMID:9594771

  9. Adherence of oral streptococci to an immobilized antimicrobial agent.

    PubMed

    Saito, T; Takatsuka, T; Kato, T; Ishihara, K; Okuda, K

    1997-08-01

    An antimicrobial agent, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, was immobilized on silica. Interaction between the material (termed) OAIS) and various oral bacterial species were then studied. Seven species of Streptococcus and two Actinomyces were investigated for their ability to adhere to this biomaterial. Cell-surface hydrophobicity and zeta-potential were examined as well. Analysis of extracted hydrophobic proteins which adhered to OAIS revealed that the adherence of these micro-organisms was closely related to the hydrophobicity of their cell surfaces. The results of zeta-potential assays indicated that negative charge on the cell surface inhibited adherence to OAIS. Gel electrophoresis revealed that OAIS could absorb cell-surface hydrophobic proteins from all bacterial species tested. Preadsorption of hydrophobic components on the cell surface inhibited adherence of the Strep. mutans strain to OAIS in a dose-dependent manner. The results indicate that OAIS adsorption of these oral bacteria was dependent on the degree of hydrophobicity of their surfaces. A major component of this adherence was hydrophobic cell-surface proteins. PMID:9347116

  10. Comparative physiological disposition of two nitrofuran anti-microbial agents.

    PubMed

    Labaune, J P; Moreau, J P; Byrne, R

    1986-01-01

    The physiological disposition of two nitrofuran derivatives used as antimicrobial agents for the treatment of acute infectious diarrhoea was evaluated in humans and animals. Upon administration of a single oral dose (600 mg) of nifurzide or nifuroxazide, no unchanged parent drug was detected in human blood or urine. In rats given 14C-nifurzide and 14C-nifuroxazide at a dose of 10 mg kg-1, 5 per cent and 17 per cent of the dose of nifurzide and nifuroxazide, respectively, were excreted in urine over a 48-hour period. None of this radioactivity was present as unchanged drug, indicating that renal excretion of both drugs occurs as metabolites. In the faeces 20 per cent of the radioactivity recovered was associated with unchanged nifuroxazide as compared with 100 per cent for nifurzide. Whole body autoradiography using rats showed that after oral administration of 14C-nifurzide and 14C-nifuroxazide, most of the radioactivity remained in the gastrointestinal lumen. PMID:3779034

  11. 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. PMID:26396358

  12. 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. PMID:27352996

  13. Antimicrobial susceptibilities of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents.

    PubMed

    Soriano, F; Zapardiel, J; Nieto, E

    1995-01-01

    The susceptibilities of 265 strains of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents were tested. Most strains were susceptible to vancomycin, doxycycline, and fusidic acid. Corynebacterium jeikeium and Corynebacterium urealyticum were the most resistant organisms tested. Resistance to beta-lactams, clindamycin, erythromycin, azythromycin, ciprofloxacin and gentamicin was common among strains of Corynebacterium xerosis and Corynebacterium minutissimum. Ampicillin resistance among Listeria monocytogenes was more prevalent than previously reported. Optochin, fosfomycin, and nitrofurantoin showed very little activity against most organisms tested, but the use of nitrofurantoin as a selective agent in culture medium may prevent the recovery of some isolates. Except for the unvarying activity of vancomycin against Corynebacterium species, the antimicrobial susceptibilities of the latter to other antibiotics are usually unpredictable, such that susceptibility tests are necessary for selecting the best antimicrobial treatment. PMID:7695308

  14. Risk assessment of growth hormones and antimicrobial residues in meat.

    PubMed

    Jeong, Sang-Hee; Kang, Daejin; Lim, Myung-Woon; Kang, Chang Soo; Sung, Ha Jung

    2010-12-01

    Growth promoters including hormonal substances and antibiotics are used legally and illegally in food producing animals for the growth promotion of livestock animals. Hormonal substances still under debate in terms of their human health impacts are estradiol-17β, progesterone, testosterone, zeranol, trenbolone, and melengestrol acetate (MGA) . Many of the risk assessment results of natural steroid hormones have presented negligible impacts when they are used under good veterinary practices. For synthetic hormonelike substances, ADIs and MRLs have been established for food safety along with the approval of animal treatment. Small amounts of antibiotics added to feedstuff present growth promotion effects via the prevention of infectious diseases at doses lower than therapeutic dose. The induction of antimicrobial resistant bacteria and the disruption of normal human intestinal flora are major concerns in terms of human health impact. Regulatory guidance such as ADIs and MRLs fully reflect the impact on human gastrointestinal microflora. However, before deciding on any risk management options, risk assessments of antimicrobial resistance require large-scale evidence regarding the relationship between antimicrobial use in food-producing animals and the occurrence of antimicrobial resistance in human pathogens. In this article, the risk profiles of hormonal and antibacterial growth promoters are provided based on recent toxicity and human exposure information, and recommendations for risk management to prevent human health impacts by the use of growth promoters are also presented. PMID:24278538

  15. Risk Assessment of Growth Hormones and Antimicrobial Residues in Meat

    PubMed Central

    Jeong, Sang-Hee; Kang, Daejin; Lim, Myung-Woon; Kang, Chang Soo

    2010-01-01

    Growth promoters including hormonal substances and antibiotics are used legally and illegally in food producing animals for the growth promotion of livestock animals. Hormonal substances still under debate in terms of their human health impacts are estradiol-17β, progesterone, testosterone, zeranol, trenbolone, and melengestrol acetate (MGA) . Many of the risk assessment results of natural steroid hormones have presented negligible impacts when they are used under good veterinary practices. For synthetic hormonelike substances, ADIs and MRLs have been established for food safety along with the approval of animal treatment. Small amounts of antibiotics added to feedstuff present growth promotion effects via the prevention of infectious diseases at doses lower than therapeutic dose. The induction of antimicrobial resistant bacteria and the disruption of normal human intestinal flora are major concerns in terms of human health impact. Regulatory guidance such as ADIs and MRLs fully reflect the impact on human gastrointestinal microflora. However, before deciding on any risk management options, risk assessments of antimicrobial resistance require large-scale evidence regarding the relationship between antimicrobial use in food-producing animals and the occurrence of antimicrobial resistance in human pathogens. In this article, the risk profiles of hormonal and antibacterial growth promoters are provided based on recent toxicity and human exposure information, and recommendations for risk management to prevent human health impacts by the use of growth promoters are also presented. PMID:24278538

  16. Environmental fate of two sulfonamide antimicrobial agents in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Veterinary antimicrobials have been detected in a number of environmental samples, including agricultural soils. In this study, the persistence and sorption of the sulfonamide sulfamethazine (SMZ) and sulfachloropyridine (SCP) in soil and their potential effects on soil microorganisms were investiga...

  17. Covalent modification of a ten-residue cationic antimicrobial peptide with levofloxacin

    NASA Astrophysics Data System (ADS)

    Rodriguez, Carlos; Papanastasiou, Emilios; Juba, Melanie; Bishop, Barney

    2014-09-01

    The rampant spread of antibiotic resistant bacteria has spurred interest in alternative strategies for developing next-generation antibacterial therapies. As such, there has been growing interest in cationic antimicrobial peptides (CAMPs) and their therapeutic applications. Modification of CAMPs via conjugation to auxiliary compounds, including small molecule drugs, is a new approach to developing effective, broad-spectrum antibacterial agents with novel physicochemical properties and versatile antibacterial mechanisms. Here, we’ve explored design parameters for engineering CAMPs conjugated to small molecules with favorable physicochemical and antibacterial properties by covalently affixing a fluoroquinolone antibiotic, levofloxacin, to the ten-residue CAMP Pep-4. Relative to the unmodified Pep-4, the conjugate was found to demonstrate substantially increased antibacterial potency under high salt concentrations. Historically, it has been observed that most CAMPs lose antibacterial effectiveness in such high ionic strength environments, a fact that has presented a challenge to their development as therapeutics. Physicochemical studies revealed that P4LC was more hydrophobic than Pep-4, while mechanistic findings indicated that the conjugate was more effective at disrupting bacterial membrane integrity. Although the inherent antibacterial effect of the incorporated levofloxacin molecules did not appear to be substantially realized in this conjugate, these findings nevertheless suggest that covalent attachment of small molecule antibiotics with favorable physicochemical properties to CAMPs could be a promising strategy for enhancing peptide performance and overall therapeutic potential. These results have broader applicability to the development of future CAMP-antibiotic conjugates for potential therapeutic applications.

  18. Antimicrobial and antioxidant activities of lignin from residue of corn stover to ethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve the economic viability of the biofuel production from biomass resource, a value-added lignin byproduct from this process is increasingly interested. Antioxidant and antimicrobial activities of lignin extracted from residue of corn stover to ethanol production were investigated. The lignin...

  19. In vitro susceptibility testing of nonsporing anaerobes to ten antimicrobial agents.

    PubMed

    Rao, P S; Shivananda, P G

    2000-07-01

    Antibiotic susceptibility was performed on sixty clinical isolates of nonsporing anaerobes against ten antimicrobial agents. The test was performed on Muller Hinton Agar and Wilkins Chalgren blood agar by preparing suspension of freshly isolated colonies in BHI broth. Apart from Metronidazole and Chloramphenicol newer antibiotics like Minocycline, Secnidazole, Tinidazole, Clarithromycin, Roxithromycin were also tried. Antimicrobial agents like Metronidazole, Secnidazole, Tinidazole and Minocycline were 100% sensitive, followed by Chloramphenicol, Clarithromycin and Roxithromycin. These newer agents can be good alternatives for the treatment of non sporing anaerobes. PMID:11218673

  20. In vitro susceptibility testing of nonsporing anaerobes to ten antimicrobial agents.

    PubMed

    Rao, P S; Shivananda, P G

    2000-04-01

    Antibiotic Susceptibility was performed on sixty clinical isolates of nonsporing anaerobes against ten antimicrobial agents. The test was performed on Muller Hinton Agar and Wilkins Chalgren blood agar by preparing suspension of freshly isolated colonies in BHI broth. Apart from Metronidazole and Chloramphenicol newer antibiotics like Minocycline, Secnidazole, Tinidazole, Clarithromycin, Roxithromycin were also tried. Antimicrobial agents like metronidazole, Secnidazole, Tinidazole and Minocycline were 100% sensitive, followed by Chloramphenicol, Clarithromycin and Roxithromycin. These newer agents can be good alternatives for the treatment of non sporing anaerobes. PMID:11217270

  1. Susceptibility of Anaerobic Bacteria to 23 Antimicrobial Agents

    PubMed Central

    Sutter, Vera L.; Finegold, Sydney M.

    1976-01-01

    The antimicrobial susceptibility of 492 anaerobic bacteria, the majority of which were recent clinical isolates, was determined by the agar dilution technique. Penicillin G was active against most of the strains tested at 32 U or less/ml, but only 72% of Bacteroides fragilis strains were susceptible at this level and 9% required 256 U or more/ml. Ampicillin was effective against most of the strains except B. fragilis at 16 μg or less/ml. Amoxicillin was active against only 31% of B. fragilis, 76% of other Bacteroides species, and 67% of Fusobacterium species at 8 μg/ml. Two new penicillins, mezlocillin and azlocillin, were similar to ampicillin in their activity. Carbenicillin and ticarcillin inhibited all but a few strains at 128 μg or less/ml. BLP 1654 was somewhat more active than penicillin G against B. fragilis but had similar activity against other anaerobes. Cephalothin was inactive against B. fragilis, and only 65% of other Bacteroides species were inhibited by 32 μg or less/ml. It was effective against all other anaerobes at that level. Cefamandole showed somewhat greater activity than cephalothin against B. fragilis but generally less activity against gram-positive organisms. Cefazaflur (SKF 59962) was comparable to cephalothin against B. fragilis. Cefoxitin was distinctly more active than cephalothin against B. fragilis. These latter two agents were less active than cephalothin against the gram-positive anaerobes. Chloramphenicol remains active against anaerobic bacteria at 16 μg or less/ml, with rare exceptions. Thiamphenicol was similar to chloramphenicol in its activity. Clindamycin was very active against most of the anaerobes at 8 μg or less/ml. Erythromycin and josamycin were also tested, with josamycin showing greater activity against B. fragilis than either erythromycin or clindamycin. A new oligosaccharide, everninomicin B, was less active than clindamycin against B. fragilis but more active against clostridia and some of the other strains

  2. EDTA: An Antimicrobial and Antibiofilm Agent for Use in Wound Care

    PubMed Central

    Finnegan, Simon; Percival, Steven L.

    2015-01-01

    Significance: Methods employed for preventing and eliminating biofilms are limited in their efficacy on mature biofilms. Despite this a number of antibiofilm formulations and technologies incorporating ethylenediaminetetraacetic acid (EDTA) have demonstrated efficacy on in vitro biofilms. The aim of this article is to critically review EDTA, in particular tetrasodium EDTA (tEDTA), as a potential antimicrobial and antibiofilm agent, in its own right, for use in skin and wound care. EDTA's synergism with other antimicrobials and surfactants will also be discussed. Recent Advances: The use of EDTA as a potentiating and sensitizing agent is not a new concept. However, currently the application of EDTA, specifically tEDTA as a stand-alone antimicrobial and antibiofilm agent, and its synergistic combination with other antimicrobials to make a “multi-pronged” approach to biofilm control is being explored. Critical Issues: As pathogenic biofilms in the wound increase infection risk, tEDTA could be considered as a potential “stand-alone” antimicrobial/antibiofilm agent or in combination with other antimicrobials, for use in both the prevention and treatment of biofilms found within abiotic (the wound dressing) and biotic (wound bed) environments. The ability of EDTA to chelate and potentiate the cell walls of bacteria and destabilize biofilms by sequestering calcium, magnesium, zinc, and iron makes it a suitable agent for use in the management of biofilms. Future Direction: tEDTA's excellent inherent antimicrobial and antibiofilm activity and proven synergistic and permeating ability results in a very beneficial agent, which could be used for the development of future antibiofilm technologies. PMID:26155384

  3. Anthocyanins as antimicrobial agents of natural plant origin.

    PubMed

    Cisowska, Agnieszka; Wojnicz, Dorota; Hendrich, Andrzej B

    2011-01-01

    Anthocyanins are particularly abundant in different fruits, especially in berries. The beneficial effects of these compounds for human health have been known from at least the 16th century. Despite the great number of papers devoted to the different biological effects exerted by anthocyanins only a limited number of studies is focused on the antimicrobial activity of these compounds. Anthocyanin content of berry fruits varies from 7.5 mg/100 mg fresh fruit in redcurrant (Ribes rubum) up to 460 mg/100 g fresh fruit in chokeberry (Aronia melanocarpa). After consumption, anthocyanins are intensively metabolized, mainly in the intestines and liver. Glucorination, methylation and sulfation are the most typical metabolic reactions. Antimicrobial activity of crude extracts of plant phenolic compounds against human pathogens has been intensively studied to characterize and develop new healthy food ingredients as well as medical and pharmaceutical products. However, there is very little information available about the antimicrobial activity of the pure anthocyanins. In the last part of this review we present the collection of papers describing the anthocyanin profiles of different fruits (mainly berries) and the antimicrobial properties of the identified compounds. Generally, anthocyanins are active against different microbes, however Gram-positive bacteria usually are more susceptible to the anthocyanin action than Gram-negative ones. Mechanisms underlying anthocyanin activity include both membrane and intracellular interactions of these compounds. Antimicrobial activity of berries and other anthocyanin-containing fruits is likely to be caused by multiple mechanisms and synergies because they contain various compounds including anthocyanins, weak organic acids, phenolic acids, and their mixtures of different chemical forms. Therefore, the antimicrobial effect of chemically complex compounds has to be critically analyzed. PMID:21366068

  4. Squalamine as an example of a new potent antimicrobial agents class: a critical review.

    PubMed

    Alhanout, K; Rolain, J M; Brunel, J M

    2010-01-01

    An important strategy to circumvent the problem of antimicrobial resistance is to search for new compounds with antimicrobial activity. In this context, aminosterols, which include squalamine-like compounds and ceragenins, have gained interest due to their wide spectrum of antibacterial and antifungal properties. In light of recently reported data, we decided to analyze the mechanism of action of these compounds as well as their antimicrobial properties. Aminosterols are active against both bacterial reference strains and multidrug-resistant antibiotics as they disrupt the integrity of the bacterial membrane. Thus, these compounds could be useful in the development of new topical decontaminants or disinfecting agents. PMID:20858213

  5. Bioconverted Products of Essential Fatty Acids as Potential Antimicrobial Agents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review deals with the recent findings on the microbial conversion of essential fatty acids (EFAs) through Pseudomonas aeruginosa PR3 NRRL-B-18602, and the antimicrobial properties of bioconverted essential fatty acids, with particular emphasis on n-3 or n-6 fatty acids. The first section deals...

  6. In Vitro Susceptibility of Equine-Obtained Isolates of Corynebacterium pseudotuberculosis to Gallium Maltolate and 20 Other Antimicrobial Agents

    PubMed Central

    Batista, M.; Lawhon, S. D.; Zhang, S.; Kuskie, K. R.; Swinford, A. K.; Bernstein, L. R.; Cohen, N. D.

    2014-01-01

    This study's objective was to determine the in vitro antimicrobial activities of gallium maltolate (GaM) and 20 other antimicrobial agents against clinical equine isolates of Corynebacterium pseudotuberculosis. The growth of cultured isolates was not inhibited by any concentration of GaM. MIC data revealed susceptibility to commonly used antimicrobials. PMID:24829243

  7. Inhibition of bacterial colonization by antimicrobial agents incorporated into dental resins.

    PubMed

    Bapna, M S; Murphy, R; Mukherjee, S

    1988-09-01

    The antimicrobial activity of several chemical agents was determined by incorporating these agents into dentine adhesive resin and following the colonization of Streptococcus mutans on the surfaces of the resin and culture vessel, as well as in the surrounding medium, by optical density measurements. It was found that sodium fluoride and dodecylamine, an organic amine, exhibited excellent antimicrobial properties. These chemicals not only inhibited bacterial growth completely but also seemed to reduce the adhesion of the bacteria to the resin surface. A silver compound, protargin, was mildly effective in inhibiting growth of S. mutans. Copper oxide and chelating acids such as vanillic acid, syringic acid, and ethylenediamine-n, n' diacetic acid (EDDA) were not effective as antimicrobial agents against S. mutans. PMID:3072391

  8. Aerosol delivery of antimicrobial agents during mechanical ventilation: current practice and perspectives.

    PubMed

    Michalopoulos, Argyris; Metaxas, Eugenios I; Falagas, Matthew E

    2011-03-01

    Critically ill patients, who develop ventilator-associated pneumonia during prolonged mechanical ventilation, often require antimicrobial agents administered through the endotracheal or the tracheotomy tube. The delivery of antibiotics via the respiratory tract has been established over the past years as an alternative route in order to deliver high concentrations of antimicrobial agents directly to the lungs and avoid systemic toxicity. Since the only formal indications for inhaled/aerosolized antimicrobial agents is for patients suffering from cystic fibrosis, consequently the majority of research and published studies concerns this group of patients. Newer devices and new antibiotic formulations are currently off-label used in ambulatory cystic fibrosis patients whereas similar data for the mechanically ventilated patients do not yet exist. PMID:21235473

  9. Susceptibility to antimicrobial agents and plasmid carrying in Aeromonas hydrophila isolated from two estuarine systems.

    PubMed

    Montoya, R; Dominguez, M; Gonzalez, C; Mondaca, M A; Zemelman, R

    1992-01-01

    Susceptibility to various antimicrobial agents and the presence of plasmids was investigated in eleven strains of Aeromonas hydrophila isolated from samples of sea water and these strains isolated from Aulacomya ater. Transference of resistance to Escherichia coli was attempted by conjugation and transformation experiments. The strains showed multiple resistance toward beta-lactam antibiotics and susceptibility to other antimicrobial agents. Five strains harboured plasmids with molecular weights below 5.7 MD. It was not possible to relate the resistance of the strains with the presence of their plasmids. PMID:1593967

  10. Susceptibility of bifidobacteria of animal origin to selected antimicrobial agents.

    PubMed

    Mayrhofer, Sigrid; Mair, Christiane; Kneifel, Wolfgang; Domig, Konrad J

    2011-01-01

    Strains of the genus Bifidobacterium are frequently used as probiotics, for which the absence of acquired antimicrobial resistance has become an important safety criterion. This clarifies the need for antibiotic susceptibility data for bifidobacteria. Based on a recently published standard for antimicrobial susceptibility testing of bifidobacteria with broth microdilution method, the range of susceptibility to selected antibiotics in 117 animal bifidobacterial strains was examined. Narrow unimodal MIC distributions either situated at the low-end (chloramphenicol, linezolid, and quinupristin/dalfopristin) or high-end (kanamycin, neomycin) concentration range could be detected. In contrast, the MIC distribution of trimethoprim was multimodal. Data derived from this study can be used as a basis for reviewing or verifying present microbiological breakpoints suggested by regulatory agencies to assess the safety of these micro-organisms intended for the use in probiotics. PMID:22312561

  11. Interactions between the antimicrobial agent triclosan and the bloom-forming cyanobacteria Microcystis aeruginosa.

    PubMed

    Huang, Xiaolong; Tu, Yenan; Song, Chaofeng; Li, Tiancui; Lin, Juan; Wu, Yonghong; Liu, Jiantong; Wu, Chenxi

    2016-03-01

    Cyanobacteria can co-exist in eutrophic waters with chemicals or other substances derived from personal care products discharged in wastewater. In this work, we investigate the interactions between the antimicrobial agent triclosan (TCS) and the bloom-forming cyanobacteria Microcystis aeruginosa. M. aeruginosa was very sensitive to TCS with the 96h lowest observed effect concentration of 1.0 and 10μg/L for inhibition of growth and photosynthetic activity, respectively. Exposure to TCS at environmentally relevant levels (0.1-2.0μg/L) also affected the activities of superoxide dismutase (SOD) and the generation of reduced glutathione (GSH), while microcystin production was not affected. Transmission electron microscope (TEM) examination showed the destruction of M. aeruginosa cell ultrastructure during TCS exposure. TCS however, can be biotransformed by M. aeruginosa with methylation as a major biotransformation pathway. Furthermore, the presence of M. aeruginosa in solution promoted the photodegradation of TCS. Overall, our results demonstrate that M. aeruginosa plays an important role in the dissipation of TCS in aquatic environments but high residual TCS can exert toxic effects on M. aeruginosa. PMID:26800489

  12. Carbon nanodots as molecular scaffolds for development of antimicrobial agents.

    PubMed

    Ngu-Schwemlein, Maria; Chin, Suk Fun; Hileman, Ryan; Drozdowski, Chris; Upchurch, Clint; Hargrove, April

    2016-04-01

    We report the potential of carbon nanodots (CNDs) as a molecular scaffold for enhancing the antimicrobial activities of small dendritic poly(amidoamines) (PAMAM). Carbon nanodots prepared from sago starch are readily functionalized with PAMAM by using N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Electron microscopy images of these polyaminated CNDs show that they are approximately 30-60nm in diameter. Infrared and fluorescence spectroscopy analyses of the water-soluble material established the presence of the polyamidoaminated moiety and the intrinsic fluorescence of the nanodots. The polyaminated nanodots (CND-PAM1 and CND-PAM2) exhibit in vitro antimicrobial properties, not only to non-multidrug resistant bacteria but also to the corresponding Gram-negative multidrug bacteria. Their minimum inhibitory concentration (MIC) ranges from 8 to 64μg/mL, which is much lower than that of PAMAM G1 or the non-active PAMAM G0 and CNDs. Additionally, they show synergistic effect in combination with tetracycline or colistin. These preliminary results imply that CNDs can serve as a promising scaffold for facilitating the rational design of antimicrobial materials for combating the ever-increasing threat of antibiotic resistance. Moreover, their fluorescence could be pertinent to unraveling their mode of action for imaging or diagnostic applications. PMID:26923697

  13. Global survey on nebulization of antimicrobial agents in mechanically ventilated patients: a call for international guidelines.

    PubMed

    Solé-Lleonart, C; Roberts, J A; Chastre, J; Poulakou, G; Palmer, L B; Blot, S; Felton, T; Bassetti, M; Luyt, C-E; Pereira, J M; Riera, J; Welte, T; Qiu, H; Rouby, J-J; Rello, J

    2016-04-01

    Nebulized antimicrobial agents are increasingly administered for treatment of respiratory infections in mechanically ventilated (MV) patients. A structured online questionnaire assessing the indications, dosages and recent patterns of use for nebulized antimicrobial agents in MV patients was developed. The questionnaire was distributed worldwide and completed by 192 intensive care units. The most common indications for using nebulized antimicrobial agent were ventilator-associated tracheobronchitis (VAT; 58/87), ventilator-associated pneumonia (VAP; 56/87) and management of multidrug-resistant, Gram-negative (67/87) bacilli in the respiratory tract. The most common prescribed nebulized agents were colistin methanesulfonate and sulfate (36/87, 41.3% and 24/87, 27.5%), tobramycin (32/87, 36.7%) and amikacin (23/87, 26.4%). Colistin methanesulfonate, amikacin and tobramycin daily doses for VAP were significantly higher than for VAT (p < 0.05). Combination of parenteral and nebulized antibiotics occurred in 50 (86%) of 58 prescriptions for VAP and 36 (64.2%) of 56 of prescriptions for VAT. The use of nebulized antimicrobial agents in MV patients is common. There is marked heterogeneity in clinical practice, with significantly different in use between patients with VAP and VAT. Randomized controlled clinical trials and international guidance on indications, dosing and antibiotic combinations to improve clinical outcomes are urgently required. PMID:26723563

  14. Studies on residue-free decontaminants for chemical warfare agents.

    PubMed

    Wagner, George W

    2015-03-17

    Residue-free decontaminants based on hydrogen peroxide, which decomposes to water and oxygen in the environment, are examined as decontaminants for chemical warfare agents (CWA). For the apparent special case of CWA on concrete, H2O2 alone, without any additives, effectively decontaminates S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate (VX), pinacolyl methylphosphorofluoridate (GD), and bis(2-choroethyl) sulfide (HD) in a process thought to involve H2O2 activation by surface-bound carbonates/bicarbonates (known H2O2 activators for CWA decontamination). A plethora of products are formed during the H2O2 decontamination of HD on concrete, and these are characterized by comparison to synthesized authentic compounds. As a potential residue-free decontaminant for surfaces other than concrete (or those lacking adsorbed carbonate/bicarbonate) H2O2 activation for CWA decontamination is feasible using residue-free NH3 and CO2 as demonstrated by reaction studies for VX, GD, and HD in homogeneous solution. Although H2O2/NH3/CO2 ("HPAC") decontaminants are active for CWA decontamination in solution, they require testing on actual surfaces of interest to assess their true efficacy for surface decontamination. PMID:25710477

  15. Antimicrobial residues in animal waste and water resources proximal to large-scale swine and poultry feeding operations.

    PubMed

    Campagnolo, Enzo R; Johnson, Kammy R; Karpati, Adam; Rubin, Carol S; Kolpin, Dana W; Meyer, Michael T; Esteban, J Emilio; Currier, Russell W; Smith, Kathleen; Thu, Kendall M; McGeehin, Michael

    2002-11-01

    Expansion and intensification of large-scale animal feeding operations (AFOs) in the United States has resulted in concern about environmental contamination and its potential public health impacts. The objective of this investigation was to obtain background data on a broad profile of antimicrobial residues in animal wastes and surface water and groundwater proximal to large-scale swine and poultry operations. The samples were measured for antimicrobial compounds using both radioimmunoassay and liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) techniques. Multiple classes of antimicrobial compounds (commonly at concentrations of > 100 microg/l) were detected in swine waste storage lagoons. In addition, multiple classes of antimicrobial compounds were detected in surface and groundwater samples collected proximal to the swine and poultry farms. This information indicates that animal waste used as fertilizer for crops may serve as a source of antimicrobial residues for the environment. Further research is required to determine if the levels of antimicrobials detected in this study are of consequence to human and/or environmental ecosystems. A comparison of the radioimmunoassay and LC/ESI-MS analytical methods documented that radioimmunoassay techniques were only appropriate for measuring residues in animal waste samples likely to contain high levels of antimicrobials. More sensitive LC/ESI-MS techniques are required in environmental samples, where low levels of antimicrobial residues are more likely. PMID:12462576

  16. Antimicrobial residues in animal waste and water resources proximal to large-scale swine and poultry feeding operations

    USGS Publications Warehouse

    Campagnolo, E.R.; Johnson, K.R.; Karpati, A.; Rubin, C.S.; Kolpin, D.W.; Meyer, M.T.; Esteban, J. Emilio; Currier, R.W.; Smith, K.; Thu, K.M.; McGeehin, M.

    2002-01-01

    Expansion and intensification of large-scale animal feeding operations (AFOs) in the United States has resulted in concern about environmental contamination and its potential public health impacts. The objective of this investigation was to obtain background data on a broad profile of antimicrobial residues in animal wastes and surface water and groundwater proximal to large-scale swine and poultry operations. The samples were measured for antimicrobial compounds using both radioimmunoassay and liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) techniques. Multiple classes of antimicrobial compounds (commonly at concentrations of >100 μg/l) were detected in swine waste storage lagoons. In addition, multiple classes of antimicrobial compounds were detected in surface and groundwater samples collected proximal to the swine and poultry farms. This information indicates that animal waste used as fertilizer for crops may serve as a source of antimicrobial residues for the environment. Further research is required to determine if the levels of antimicrobials detected in this study are of consequence to human and/or environmental ecosystems. A comparison of the radioimmunoassay and LC/ESI-MS analytical methods documented that radioimmunoassay techniques were only appropriate for measuring residues in animal waste samples likely to contain high levels of antimicrobials. More sensitive LC/ESI-MS techniques are required in environmental samples, where low levels of antimicrobial residues are more likely.

  17. Assessment of antimicrobial drug residues in beef in Abuja, the Federal Capital Territory, Nigeria.

    PubMed

    Omeiza, Gabriel K; Ajayi, Itopa E; Ode, Okwoche J

    2012-01-01

    Drugs administered to food-producing animals close to the time of slaughter often result in prohibited antimicrobial residues in the animal tissues at slaughter. Evidence based on the Premi® test confirmed the occurrence of antimicrobial drug residues in 89.3% of kidney and urine samples from cattle slaughtered within Abuja town where the residents rely heavily on beef as a source of protein. The administration of antibiotics close to the time of slaughter by marketers/herd owners and transporters was found to be significantly (p<0.05) higher when compared with butchers and abattoir workers. The practice of administering antibiotics to animals close to the time of slaughter was believed to be profit-motivated. The research suggests that awareness campaigns amongst the stakeholders, the enactment of appropriate laws for the control of antibiotic use and the empowerment of veterinary public health practitioners in food regulatory agencies as some of the strategies which may positively reduce the risk of antimicrobial drug residues in food animals in Nigeria. PMID:23038074

  18. The in vitro activity of 15 antimicrobial agents against bacterial isolates from dogs.

    PubMed

    Awji, Elias Gebru; Damte, Dereje; Lee, Seung-Jin; Lee, Joong-Su; Kim, Young-Hoan; Park, Seung-Chun

    2012-08-01

    The in vitro activity of 15 antimicrobial agents against clinical isolates of Staphylococcus pseudintermedius, Staphylococcus aureus, Escherichia coli, Pasteurella spp. and Streptococcus canis from dogs was investigated. For Staphylococcus spp., the highest frequency of resistance was observed for penicillin, followed by ampicillin, tetracycline and chloramphenicol. The highest frequency of resistance in E. coli isolates was recorded for tetracycline and streptomycin. Pasteurella spp. and S. canis had the highest resistance rate for tetracycline and chloramphenicol. Most isolates showed full susceptibility to low-level resistance to colistin, florfenicol and fluoroquinolones. Further studies using larger number of isolates from both healthy and diseased dogs would provide a broader picture of antimicrobial resistance at a national level and promote prudent use of antimicrobial agents in companion animals. PMID:22516694

  19. Mutant prevention concentration and mutant selection window for 10 antimicrobial agents against Rhodococcus equi.

    PubMed

    Berghaus, Londa J; Giguère, Steeve; Guldbech, Kristen

    2013-10-25

    The objectives of this study were to determine the mutant prevention concentration (MPC), time above the MPC and mutant selection window for 10 antimicrobial agents against Rhodococcus equi and to determine if the combination of a macrolide with rifampin would decrease emergence of resistant mutants. Antimicrobial agents investigated (erythromycin, clarithromycin, azithromycin, rifampin, amikacin, gentamicin, enrofloxacin, vancomycin, imipenem, and doxycycline) were selected based on in vitro activity and frequency of use in foals or people infected with R. equi. Each antimicrobial agent or combination of agents was evaluated against four virulent strains of R. equi. MPC were determined using an agar plate assay. Pharmacodynamic parameters were calculated using published plasma and pulmonary pharmacokinetic variables. There was a significant (P<0.001) effect of the type of antimicrobial agent on the MPC. The MPC of clarithromycin (1.0 μg/ml) was significantly lower and the MPC of rifampin and amikacin (512 and 384 μg/ml, respectively) were significantly higher than that of all other antimicrobial agents tested. Combining erythromycin, clarithromycin, or azithromycin with rifampin resulted in a significant (P≤0.005) decrease in MPC and MPC/MIC ratio. When MIC and MPC were combined with pharmacokinetic variables, only gentamicin and vancomycin were predicted to achieve plasma concentrations above the MPC for any given periods of time. Only clarithromycin and the combination clarithromycin-rifampin were predicted to achieve concentrations in bronchoalveolar cells and pulmonary epithelial lining fluid above the MPC for the entire dosing interval. In conclusion, the combination of a macrolide with rifampin considerably decreases the emergence of resistant mutants of R. equi. PMID:23915992

  20. Benzofuran as a promising scaffold for the synthesis of antimicrobial and antibreast cancer agents: A review

    PubMed Central

    Khodarahmi, Ghadamali; Asadi, Parvin; Hassanzadeh, Farshid; Khodarahmi, Elham

    2015-01-01

    Benzofuran as an important heterocyclic compound is extensively found in natural products as well as synthetic materials. Since benzofuran drivatives display a diverse array of pharmacological activities, an interest in developing new biologically active agents from benzofuran is still under consideration. This review highlights recent findings on biological activities of benzofuran derivatives as antimicrobial and antibreast cancer agents and lays emphasis on the importance of benzofurans as a major source for drug design and development. PMID:26941815

  1. 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…

  2. Evaluating bionanoparticle infused fungal metabolites as a novel antimicrobial agent

    PubMed Central

    Rajpal, Kartikeya; Aziz, Nafe; Prasad, Ram; Varma, Ramendra G.; Varma, Ajit

    2016-01-01

    Therapeutic properties of fungal metabolites and silver nanoparticles have been well documented. While fungal metabolites have been used for centuries as medicinal drugs, potential of biogenic silver nanoparticles has recently received attention. We have evaluated the antimicrobial potential of Aspergillus terreus crude extract, silver nanoparticles and an amalgamation of both against four pathogenic bacterial strains. Antimicrobial activity of the following was evaluated – A. terreus extract, biogenic silver nanoparticles, and a mixture containing extract and nanoparticles. Four pathogenic bacteria - Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, and Bacillus cereus were used as test organisms. Phenol, flavonoid, and alkaloid content of extract were determined to understand the chemical profile of the fungus. The extract contained significantly high amounts of phenols, flavonoids, and alkaloids. The extract and biogenic silver nanoparticle exhibited significant antibacterial activity at concentrations of 10 μg/ml and 1 μg/ml, respectively. When used in combination, the extract-nanoparticle mixture showed equally potent antibacterial activity at a much lower concentration of 2.5 μg/ml extract + 0.5 μg/ml nanoparticle. Given its high antibacterial potential, the fungal extract can be a promising source of novel drug lead compounds. The extract – silver nanoparticle mixture exhibited synergism in their antibacterial efficacy. This property can be further used to formulate new age drugs. PMID:27429931

  3. 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. PMID:22421330

  4. Antimicrobial agents from higher plants. The antimicrobially inactive components of Ptelea trifoliata L.

    PubMed

    Mitscher, L A; Bathala, M S; Clark, G W; Beal, J L

    1975-01-01

    From the weakly antibacterial non-quaternary alkaloidal fractions from Ptelea trifoliata L. (Rutaceae), ten tertiary quinol-2-one and quinol-4-one alkaloids were isolated and identified. In addition, beta-sitosterol, beta-sitosteryl-beta-D-glucoside and bergapten were isolated. None of these compounds possessed perceptible antimicrobial activity. The weak antimicrobial activity of the neutral and alkaloidal fractions was traced to small amounts of pteleatinium chloride which had not been completely separated by bulk processes. Alkaloids previously known to be present in P. trifoliata which were found in this study ptelefoline methyl ether, pteleine and skimmianine. Alkaloids previously known but new to this plant were lunidoine and isomaculasidine. Alkaloids newly found in nature were neohydroxylunine, hydroxylunidonine, 6-methoxylunidoine, 6-methoxylunineand 6-methoxy-hydroxylunidine. The structure of the latter three bases is proposed tentatively. PMID:1134209

  5. Dairy farm age and resistance to antimicrobial agents in Escherichia coli isolated from dairy topsoil.

    PubMed

    Jones, Suzanna E; Burgos, Jonathan M; Lutnesky, Marvin M F; Sena, Johnny A; Kumar, Sanath; Jones, Lindsay M; Varela, Manuel F

    2011-04-01

    Antimicrobial agent usage is common in animal agriculture for therapeutic and prophylactic purposes. Selective pressure exerted by these antimicrobials on soil bacteria could result in the selection of strains that are resistant due to chromosomal- or plasmid-derived genetic components. Multiple antimicrobial resistances in Escherichia coli and the direct relationship between antimicrobial agent use over time has been extensively studied, yet the relationship between the age of an animal agriculture environment such as a dairy farm and antibiotic resistance remains unclear. Therefore, we tested the hypothesis that antimicrobial-resistance profiles of E. coli isolated from dairy farm topsoil correlate with dairy farm age. E. coli isolated from eleven dairy farms of varying ages within Roosevelt County, NM were used for MIC determinations to chloramphenicol, nalidixic acid, penicillin, tetracycline, ampicillin, amoxicillin/clavulanic acid, gentamicin, trimethoprim/sulfamethoxazole, cefotaxime, and ciprofloxacin. The minimum inhibitory concentration values of four antibiotics ranged 0.75 to >256 μg/ml, 1 to >256 μg/ml, 12 to >256 μg/ml, and 0.75 to >256 μg/ml for chloramphenicol, nalidixic acid, penicillin, and tetracycline, respectively. The study did not show a direct relationship between antibiotic resistance and the age of dairy farms. PMID:21153729

  6. Inhibitory effects of antimicrobial agents against Fusarium species.

    PubMed

    Kawakami, Hideaki; Inuzuka, Hiroko; Hori, Nobuhide; Takahashi, Nobumichi; Ishida, Kyoko; Mochizuki, Kiyofumi; Ohkusu, Kiyofumi; Muraosa, Yasunori; Watanabe, Akira; Kamei, Katsuhiko

    2015-08-01

    We investigated the inhibitory effects of antibacterial, biocidal, and antifungal agents against Fusarium spp. Seven Fusarium spp: four F. falciforme (Fusarium solani species complex), one Fusarium spp, one Fusarium spp. (Fusarium incarnatum-equiseti species complex), and one F. napiforme (Gibberella fujikuroi species complex), isolated from eyes with fungal keratitis were used in this study. Their susceptibility to antibacterial agents: flomoxef, imipenem, gatifloxacin, levofloxacin, moxifloxacin, gentamicin, tobramycin, and Tobracin® (contained 3,000 μg/ml of tobramycin and 25 μg/ml of benzalkonium chloride (BAK), a biocidal agent: BAK, and antifungal agents: amphotericin B, pimaricin (natamycin), fluconazole, itraconazole, miconazole, voriconazole, and micafungin, was determined by broth microdilution tests. The half-maximal inhibitory concentration (IC50), 100% inhibitory concentration (IC100), and minimum inhibitory concentration (MIC) against the Fusarium isolates were determined. BAK had the highest activity against the Fusarium spp. except for the antifungal agents. Three fluoroquinolones and two aminoglycosides had inhibitory effects against the Fusarium spp. at relatively high concentrations. Tobracin® had a higher inhibitory effect against Fusarium spp. than tobramycin alone. Amphotericin B had the highest inhibitory effect against the Fusarium spp, although it had different degrees of activity against each isolate. Our findings showed that fluoroquinolones, aminoglycosides, and BAK had some degree of inhibitory effect against the seven Fusarium isolates, although these agents had considerably lower effect than amphotericin B. However, the inhibitory effects of amphotericin B against the Fusarium spp. varied for the different isolates. Further studies for more effective medications against Fusarium, such as different combinations of antibacterial, biocidal, and antifungal agents are needed. PMID:25841054

  7. 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

  8. Photo induced silver on nano titanium dioxide as an enhanced antimicrobial agent for wool.

    PubMed

    Montazer, Majid; Behzadnia, Amir; Pakdel, Esfandiar; Rahimi, Mohammad Karim; Moghadam, Mohammad Bameni

    2011-06-01

    In this study an effective nanocomposite antimicrobial agent for wool fabric was introduced. The silver loaded nano TiO(2) as a nanocomposite was prepared through UV irradiation in an ultrasonic bath. The nanocomposite was stabilized on the wool fabric surface by using citric acid as a friendly cross-linking agent. The treated wool fabrics indicated an antimicrobial activity against both Staphylococcus aureus and Escherichia coli bacteria. Increasing the concentration of Ag/TiO(2) nanocomposite led to an improvement in antibacterial activities of the treated fabrics. Also increasing the amount of citric acid improved the adsorption of Ag/TiO(2) on the wool fabric surface leading to enhance antibacterial activity. The EDS spectrum, SEM images, and XRD patterns was studied to confirm the presence of existence of nanocomposite on the fabric surface. The role of both cross-linking agent and nanocomposite concentrations on the results was investigated using response surface methodology (RSM). PMID:21474327

  9. Metabolic Network Analysis-Based Identification of Antimicrobial Drug Targets in Category A Bioterrorism Agents

    PubMed Central

    Ahn, Yong-Yeol; Lee, Deok-Sun; Burd, Henry; Blank, William; Kapatral, Vinayak

    2014-01-01

    The 2001 anthrax mail attacks in the United States demonstrated the potential threat of bioterrorism, hence driving the need to develop sophisticated treatment and diagnostic protocols to counter biological warfare. Here, by performing flux balance analyses on the fully-annotated metabolic networks of multiple, whole genome-sequenced bacterial strains, we have identified a large number of metabolic enzymes as potential drug targets for each of the three Category A-designated bioterrorism agents including Bacillus anthracis, Francisella tularensis and Yersinia pestis. Nine metabolic enzymes- belonging to the coenzyme A, folate, phosphatidyl-ethanolamine and nucleic acid pathways common to all strains across the three distinct genera were identified as targets. Antimicrobial agents against some of these enzymes are available. Thus, a combination of cross species-specific antibiotics and common antimicrobials against shared targets may represent a useful combinatorial therapeutic approach against all Category A bioterrorism agents. PMID:24454817

  10. CO-releasing Metal Carbonyl Compounds as Antimicrobial Agents in the Post-antibiotic Era*

    PubMed Central

    Wareham, Lauren K.; Poole, Robert K.; Tinajero-Trejo, Mariana

    2015-01-01

    The possibility of a “post-antibiotic era” in the 21st century, in which common infections may kill, has prompted research into radically new antimicrobials. CO-releasing molecules (CORMs), mostly metal carbonyl compounds, originally developed for therapeutic CO delivery in animals, are potent antimicrobial agents. Certain CORMs inhibit growth and respiration, reduce viability, and release CO to intracellular hemes, as predicted, but their actions are more complex, as revealed by transcriptomic datasets and modeling. Progress is hindered by difficulties in detecting CO release intracellularly, limited understanding of the biological chemistry of CO reactions with non-heme targets, and the cytotoxicity of some CORMs to mammalian cells. PMID:26055702

  11. Plant Antimicrobial Agents and Their Effects on Plant and Human Pathogens

    PubMed Central

    González-Lamothe, Rocío; Mitchell, Gabriel; Gattuso, Mariza; Diarra, Moussa S.; Malouin, François; Bouarab, Kamal

    2009-01-01

    To protect themselves, plants accumulate an armoury of antimicrobial secondary metabolites. Some metabolites represent constitutive chemical barriers to microbial attack (phytoanticipins) and others inducible antimicrobials (phytoalexins). They are extensively studied as promising plant and human disease-controlling agents. This review discusses the bioactivity of several phytoalexins and phytoanticipins defending plants against fungal and bacterial aggressors and those with antibacterial activities against pathogens affecting humans such as Pseudomonas aeruginosa and Staphylococcus aureus involved in respiratory infections of cystic fibrosis patients. The utility of plant products as “antibiotic potentiators” and “virulence attenuators” is also described as well as some biotechnological applications in phytoprotection. PMID:20111686

  12. Simple isoquinoline and benzylisoquinoline alkaloids as potential antimicrobial, antimalarial, cytotoxic, and anti-HIV agents.

    PubMed

    Iwasa, K; Moriyasu, M; Tachibana, Y; Kim, H S; Wataya, Y; Wiegrebe, W; Bastow, K F; Cosentino, L M; Kozuka, M; Lee, K H

    2001-11-01

    Twenty-six simple isoquinolines and 21 benzylisoquinolines were tested for antimicrobial, antimalarial, cytotoxic, and anti-HIV activities. Some simple isoquinoline alkaloids were significantly active in each assay, and may be useful as lead compounds for developing potential chemotherapeutic agents. These compounds include 13 (antimicrobial), 25, 26, and 42 (antimalarial), 13 and 25 (cytotoxic), and 28 and 29 (anti-HIV). A quaternary nitrogen atom of isoquinolium or dihydroisoquinolinium type may contribute to enhanced potency in the first three types of activities. In contrast, anti-HIV activity was found with tetrahydroisoquinoline and 6,7-dihydroxyisoquinolium salts. PMID:11597468

  13. 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

  14. In vitro synergy, pharmacodynamics, and postantibiotic effect of 11 antimicrobial agents against Rhodococcus equi.

    PubMed

    Giguère, Steeve; Lee, Elise A; Guldbech, Kristen M; Berghaus, Londa J

    2012-11-01

    There are no studies investigating interactions between clarithromycin or azithromycin and rifampin or other commonly used antimicrobial agents against virulent isolates of Rhodococcus equi. In addition, there is no published data on the postantibiotic effects (PAEs) and pharmacodynamics properties of antimicrobial agents against R. equi. The objectives were to assess in vitro interactions, pharmacodynamics, and PAEs of 11 antimicrobial agents belonging to various antimicrobial classes against R. equi. Antimicrobial agents investigated (erythromycin, clarithromycin, azithromycin, rifampin, amikacin, gentamicin, enrofloxacin, vancomycin, imipenem, ceftiofur, and doxycycline) were selected based on in vitro activity against large numbers of isolates of R. equi and frequency of use in foals or humans infected with R. equi. Three virulent strains of R. equi were evaluated by time-kill curves and checkerboard assays, and the postantibiotic effect was measured at 5×MIC. Only amikacin, gentamicin, enrofloxacin, and vancomycin were bactericidal against R. equi. Combinations including a macrolide (erythromycin, clarithromycin, azithromycin) and either rifampin or doxycycline, and the combination doxycycline-rifampin were synergistic. Combinations containing amikacin and erythromycin, clarithromycin, azithromycin, or rifampin and the combination gentamicin-rifampin were antagonistic. The PAEs of rifampin, erythromycin, clarithromycin, vancomycin, and doxycycline were relatively long with median values ranging between 4.5 and 6.5h. Azithromycin, gentamicin, and imipenem had intermediate PAEs ranging between 3.3 and 3.5h. Amikacin, enrofloxacin, and ceftiofur had shorter PAEs ranging between 1.3 and 2.1h. Gentamicin, amikacin, enrofloxacin, and doxycycline exhibited concentration-dependent activity whereas erythromycin, clarithromycin, azithromycin, rifampin, ceftiofur, imipenem, and vancomycin exhibited time-dependent activity against R. equi. PMID:22704561

  15. Silver-Lactoferrin Nanocomplexes as a Potent Antimicrobial Agent.

    PubMed

    Pomastowski, Paweł; Sprynskyy, Myroslav; Žuvela, Petar; Rafińska, Katarzyna; Milanowski, Maciej; Liu, J Jay; Yi, Myunggi; Buszewski, Bogusław

    2016-06-29

    The process of silver immobilization onto and/or into bovine lactoferrin (LTF), the physicochemical properties of bovine lactoferrin and obtained silver-lactoferrin complexes, as well as antibacterial activity of silver-lactoferrin complexes were investigated in this work. Kinetic study of the silver immobilization into lactoferrin was carried out using batch sorption techniques. Spectrometric (MALDI-TOF/TOF-MS, ICP-MS), spectroscopic (FTIR, SERS), electron microscopic (TEM) and electrophoretic (I-DE) techniques, as well as zeta potential measurements, were applied for characterization of LTF and binding nature of silver in Ag-LTF complexes. On the basis of the results of the kinetics study, it was established that the silver binding to LTF is a heterogeneous process involving two main stages: (i) internal diffusion and sorption onto external surface of lactoferrin globules; and (ii) internal diffusion and binding into lactoferrin globule structure. Spectroscopic techniques combined with TEM analysis confirmed the binding process. Molecular dynamics (MD) analysis was carried out in order to simulate the mechanism of the binding process, and locate potential binding sites, as well as complement the experimental findings. Quantum mechanics (QM) simulations were performed utilizing density functional theory (DFT) in order to support the reduction mechanism of silver ions to elemental silver. Antimicrobial activity of synthesized lactoferrin complexes against selected clinical bacteria was confirmed using flow cytometry and antibiograms. PMID:27263865

  16. The Role and Efficacy of Herbal Antimicrobial Agents in Orthodontic Treatment

    PubMed Central

    Mishra, Sumita; Kumar Sahu, Sanjeeb; Bhusan Nanda, Smruti; Charan Sahu, Kanhu

    2014-01-01

    Aims: To assess the effect of herbal antimicrobial agents on Streptococcus mutans count in biofilm formations during orthodontic treatment. Materials and Methods: We calculated the growth inhibition of oral bacteria in the orthodontic appliances after herbal antibacterial agents were placed in culture media. The Minimum Inhibitory Concentrations (MICs) of these agents on Streptococcus mutans growth were determined. After cultivating colonies of Streptococci in biofilm medium with these herbal antimicrobial agents and orthodontic attachments, viable cell counting was performed from the bacteria which were attached on them. Scanning electron microscopy (SEM) analysis of morphology was observed on bacterial cells which were attached to orthodontic attachments. The effects of these agents were then evaluated and recommendations were forwarded. Results: There was an increase in count of Streptococcus mutans with respect to the herbal antibacterial agents. Conclusion: Despite the antibacterial functions of these herbal agents, there was increase in the biofilm formation caused by Streptococcus mutans to orthodontic bands, which had occurred most likely through upregulation of glucosyl transferase expression. These extracts may thus play an important role in increased bacterial attachment to orthodontic wires. Thus, this study was corroborative of an amalgamation of Ayurvedic therapy and Orthodontic treatment. PMID:25121056

  17. Small Antimicrobial Agents Based on Acylated Reduced Amide Scaffold.

    PubMed

    Teng, Peng; Huo, Da; Nimmagadda, Alekhya; Wu, Jianfeng; She, Fengyu; Su, Ma; Lin, Xiaoyang; Yan, Jiyu; Cao, Annie; Xi, Chuanwu; Hu, Yong; Cai, Jianfeng

    2016-09-01

    Prevalence of drug-resistant bacteria has emerged to be one of the greatest threats in the 21st century. Herein, we report the development of a series of small molecular antibacterial agents that are based on the acylated reduced amide scaffold. These molecules display good potency against a panel of multidrug-resistant Gram-positive and Gram-negative bacterial strains. Meanwhile, they also effectively inhibit the biofilm formation. Mechanistic studies suggest that these compounds kill bacteria by compromising bacterial membranes, a mechanism analogous to that of host-defense peptides (HDPs). The mechanism is further supported by the fact that the lead compounds do not induce resistance in MRSA bacteria even after 14 passages. Lastly, we also demonstrate that these molecules have therapeutic potential by preventing inflammation caused by MRSA induced pneumonia in a rat model. This class of compounds could lead to an appealing class of antibiotic agents combating drug-resistant bacterial strains. PMID:27526720

  18. Potential of medicinal plants as antimicrobial and antioxidant agents in food industry: a hypothesis.

    PubMed

    Ortega-Ramirez, Luis Alberto; Rodriguez-Garcia, Isela; Leyva, Juan Manuel; Cruz-Valenzuela, Manuel Reynaldo; Silva-Espinoza, Brenda Adriana; Gonzalez-Aguilar, Gustavo A; Siddiqui, Wasim; Ayala-Zavala, Jesus Fernando

    2014-02-01

    Many food preservation strategies can be used for the control of microbial spoilage and oxidation; however, these quality problems are not yet controlled adequately. Although synthetic antimicrobial and antioxidant agents are approved in many countries, the use of natural safe and effective preservatives is a demand of food consumers and producers. This paper proposes medicinal plants, traditionally used to treat health disorders and prevent diseases, as a source of bioactive compounds having food additive properties. Medicinal plants are rich in terpenes and phenolic compounds that present antimicrobial and antioxidant properties; in addition, the literature revealed that these bioactive compounds extracted from other plants have been effective in food systems. In this context, the present hypothesis paper states that bioactive molecules extracted from medicinal plants can be used as antimicrobial and antioxidant additives in the food industry. PMID:24446991

  19. Emerging resistance to newer antimicrobial agents among Shigella isolated from Finnish foreign travellers.

    PubMed

    Haukka, K; Siitonen, A

    2008-04-01

    In Finland, most cases of shigellosis are related to travel abroad. Antimicrobial drug resistance of 1814 Shigella strains isolated from Finnish patients during 1990-2005 was studied using discs of 12 antimicrobial agents. Since 2000, the E-test has been performed to determine ciprofloxacin minimum inhibitory concentrations of nalidixic acid-resistant isolates. The proportion of multi-resistant strains (resistant to >or =4 antimicrobials) was highest among isolates from China and India, but is increasing significantly in other parts of Asia. Resistance to nalidixic acid has become common among the strains from the Far East, and the first isolates also resistant to ciprofloxacin were detected during 2004-2005. All the ciprofloxacin-resistant isolates belonged to the S. flexneri 2a serotype. All the nalidixic acid-resistant S. flexneri strains had reduced susceptibility to ciprofloxacin, whereas 23% of the nalidixic acid-resistant S. sonnei strains were still completely susceptible to ciprofloxacin. PMID:17578602

  20. 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.

  1. [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. PMID:17583653

  2. Biological activity assessment of a novel contraceptive antimicrobial agent.

    PubMed

    Garg, A; Anderson, R A; Zaneveld, L J D; Garg, S

    2005-01-01

    Microbicides are a new category of compounds being developed as a prophylactic approach for the prevention of transmission of sexually transmitted diseases (STDs), including the human immunodeficiency virus (HIV). These are primarily being developed as women-controlled methods, with the target of designing new compounds or formulations that can be used without the knowledge of a male partner. Microbicide screening can be initially based on their hyaluronidase-inhibiting (HI) activity, as this enzyme plays a major role in the sperm and microbe penetration into the substrate. Derivatives of hesperidin, a citrus flavonoid glycoside, have been reported in the literature for their HI effects. Hesperidin was thereby sulphonated under strictly controlled conditions and the active fraction isolated and characterized, based on its HI activity. This derivative was screened for antimicrobial and enzyme-inhibitory activities, specifically for the reproductive tract. Sulphonated hesperidin (SH) was found to completely inhibit the sperm enzymes hyaluronidase, giving an indication toward its contraceptive effects. It was also been found to inhibit various sexually transmitted pathogens, including Chlamydia trachomatis, Neisseria gonorrhoea, HIV, and Herpes Simplex virus type 2 (HSV-2). Its safety assessment was based on its noninterference in sperm motility and its penetration through the cervical mucus, and no effect on the growth of lactobacilli, the normal vaginal flora. It was also found to be nontoxic to the HIV substrate cells (MT2 cells). The study concludes that sulphonated hesperidin can be developed as a potential microbicide for a dual prophylaxis of contraception and transmission of STDs and AIDS. PMID:15867010

  3. 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

    2016-03-01

    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

  4. 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. PMID:27116299

  5. 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

  6. 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. PMID:26849681

  7. Chemokine-Derived Peptides: Novel Antimicrobial and Antineoplasic Agents.

    PubMed

    Valdivia-Silva, Julio; Medina-Tamayo, Jaciel; Garcia-Zepeda, Eduardo A

    2015-01-01

    Chemokines are a burgeoning family of chemotactic cytokines displaying a broad array of functions such as regulation of homeostatic leukocyte traffic and development, as well as activating the innate immune system. Their role in controlling early and late inflammatory stages is now well recognized. An improper balance either in chemokine synthesis or chemokine receptor expression contributes to various pathological disorders making chemokines and their receptors a useful therapeutic target. Research in this area is progressing rapidly, and development of novel agents based on chemokine/ chemokine receptors antagonist functions are emerging as attractive alternative drugs. Some of these novel agents include generation of chemokine-derived peptides (CDP) with potential agonist and antagonist effects on inflammation, cancer and against bacterial infections. CDP have been generated mainly from N- and C-terminus chemokine sequences with subsequent modifications such as truncations or elongations. In this review, we present a glimpse of the different pharmacological actions reported for CDP and our current understanding regarding the potential use of CDP alone or as part of the novel therapies proposed in the treatment of microbial infections and cancer. PMID:26062132

  8. Chemokine-Derived Peptides: Novel Antimicrobial and Antineoplasic Agents

    PubMed Central

    Valdivia-Silva, Julio; Medina-Tamayo, Jaciel; Garcia-Zepeda, Eduardo A.

    2015-01-01

    Chemokines are a burgeoning family of chemotactic cytokines displaying a broad array of functions such as regulation of homeostatic leukocyte traffic and development, as well as activating the innate immune system. Their role in controlling early and late inflammatory stages is now well recognized. An improper balance either in chemokine synthesis or chemokine receptor expression contributes to various pathological disorders making chemokines and their receptors a useful therapeutic target. Research in this area is progressing rapidly, and development of novel agents based on chemokine/chemokine receptors antagonist functions are emerging as attractive alternative drugs. Some of these novel agents include generation of chemokine-derived peptides (CDP) with potential agonist and antagonist effects on inflammation, cancer and against bacterial infections. CDP have been generated mainly from N- and C-terminus chemokine sequences with subsequent modifications such as truncations or elongations. In this review, we present a glimpse of the different pharmacological actions reported for CDP and our current understanding regarding the potential use of CDP alone or as part of the novel therapies proposed in the treatment of microbial infections and cancer. PMID:26062132

  9. Resistance of gram-negative bacilli as related to hospital use of antimicrobial agents.

    PubMed Central

    Ma, M Y; Goldstein, E J; Friedman, M H; Anderson, M S; Mulligan, M E

    1983-01-01

    The development of resistance of gram-negative bacilli, which are common nosocomial pathogens, is an increasing problem. It is generally accepted that this resistance may directly reflect the frequency of use of various antimicrobial agents. Because our institution experienced in 1976 a dramatic change in the pattern of antimicrobial use, primarily a marked decrease in prescribing cephalosporins, we attempted to evaluate retrospectively the effects of this change upon the resistance of gram-negative bacilli that are common nosocomial pathogens. Susceptibilities of Klebsiella and Providencia spp., Pseudomonas aeruginosa, and Serratia marcescens were determined for the years 1975 to 1979. Not unexpectedly, we observed a substantial decrease in cephalosporin resistance. An unexpected finding was a decrease in aminoglycoside resistance, despite increased use of these agents. The possibility that decreased cephalosporin use may lead to decreased aminoglycoside resistance is an intriguing and provocative thesis which can only be speculative at this time but which would seem worthy of additional formal investigation. PMID:6638994

  10. The therapeutic effect of 16 antimicrobial agents on Cryptosporidium infection in mice.

    PubMed

    Tzipori, S R; Campbell, I; Angus, K W

    1982-04-01

    The therapeutic efficiency of 16 anti-microbial agents (Ethopabate, Nicarbazin, Sulphaquinoxaline, Furaltadone, Enterolyte-N, Sulphamethazine, Trinamide, Amprol, Phenamidine, Zoaquin, Halofuginone, Salinomycin, Monensin, Emtryl, Arprinocid and Amprolium) were examined against Cryptosporidium infections in mice. The Cryptosporidium was originally isolated from a field outbreak of calf diarrhoea. The drugs neither prevented nor modified the course of the infection as compared with infected, untreated mice. PMID:7115220

  11. 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. PMID:26257400

  12. Development and spread of bacterial resistance to antimicrobial agents: an overview.

    PubMed

    Tenover, F C

    2001-09-15

    Resistance to antimicrobial agents is emerging in a wide variety of nosocomial and community-acquired pathogens. The emergence and spread of multiply resistant organisms represent the convergence of a variety of factors that include mutations in common resistance genes that extend their spectrum of activity, the exchange of genetic information among microorganisms, the evolution of selective pressures in hospitals and communities that facilitate the development and spread of resistant organisms, the proliferation and spread of multiply resistant clones of bacteria, and the inability of some laboratory testing methods to detect emerging resistance phenotypes. Twenty years ago, bacteria that were resistant to antimicrobial agents were easy to detect in the laboratory because the concentration of drug required to inhibit their growth was usually quite high and distinctly different from that of susceptible strains. Newer mechanisms of resistance, however, often result in much more subtle shifts in bacterial population distributions. Perhaps the most difficult phenotypes to detect, as shown in several proficiency testing surveys, are decreased susceptibility to beta-lactams in pneumococci and decreased susceptibility to vancomycin in staphylococci. In summary, emerging resistance has required adaptations and modifications of laboratory diagnostic techniques, empiric anti-infective therapy for such diseases as bacterial meningitis, and infection control measures in health care facilities of all kinds. Judicious use is imperative if we are to preserve our arsenal of antimicrobial agents into the next decade. PMID:11524705

  13. Medical applications of nanoparticles in biological imaging, cell labeling, antimicrobial agents, and anticancer nanodrugs.

    PubMed

    Singh, Ravina; Nalwa, Hari Singh

    2011-08-01

    This article reviews the applications of nanotechnology in the fields of medical and life sciences. Nanoparticles have shown promising applications from diagnosis to treatment of various types of diseases including cancer. In this review, we discuss the applications of nanostructured materials such as nanoparticles, quantum dots, nanorods, nanowires, and carbon nanotubes in diagnostics, biomarkers, cell labeling, contrast agents for biological imaging, antimicrobial agents, drug delivery systems, and anticancer nanodrugs for treatment of cancer and other infectious diseases. The adverse affects of nanoparticles on human skin from daily use in cosmetics and general toxicology of nanoscale materials are also reviewed. PMID:21870454

  14. Protective effects of intravenous immunoglobulin and antimicrobial agents on acute pneumonia in leukopenic mice.

    PubMed

    Shimizu, Masaru; Katoh, Hideya; Hamaoka, Saeko; Kinoshita, Mao; Akiyama, Koichi; Naito, Yoshifumi; Sawa, Teiji

    2016-04-01

    Multi-drug resistant Pseudomonas aeruginosa causes the type of acute lung injury that is strongly associated with bacteremia, sepsis, and mortality, especially under immunocompromised conditions. Although administration of immunoglobulin solution is an applicable immunotherapy in immunocompromised patients, efficacy of immunoglobulin administration against multi-drug resistant P. aeruginosa pneumonia has not been well evaluated. In this study, we investigated the effectiveness of prophylactic administration of immunoglobulin solution (IVIG) in comparison with that of other types of antimicrobial agents, such as anti-PcrV IgG, piperacillin/tazobactam, or colistin in an immunocompromised mouse model of P. aeruginosa pneumonia. Colistin was the most effective agent for preventing acute lung injury, bacteremia, cytokinemia, and sepsis. Among the four tested antimicrobial agents, after colistin, anti-PcrV IgG and IVIG were the most effective at protecting mice from mortality. Piperacillin/tazobactam did not prevent acute lung injury or bacteremia; rather, it worsened lung histology. The data suggest that using an agent for which a positive result in an in vitro susceptibility test has been obtained may not always prevent acute lung injury in a leukopenic host infected with P. aeruginosa. Clinicians should consider the possibility of discrepancies between in vitro and in vivo tests because the absence of in vitro bactericidal activity in an antimicrobial agent is not always a reliable predictor of its lack of ability to eradicate bacteria in vivo, even in immunocompromised hosts. Based on our findings, the potential protective effects of IVIG against the acute lung injury induced by P. aeruginosa should be reevaluated. PMID:26867796

  15. Resistance to antimicrobial agents of Campylobacter spp. strains isolated from animals in Poland.

    PubMed

    Krutkiewicz, A; Sałamaszyńska-Guz, A; Rzewuska, M; Klimuszko, D; Binek, M

    2009-01-01

    A total of 69 Campylobacter jejuni and 16 Campylobacter coli strains isolated from chicken, dog and pig stool samples were characterized based on their resistance to five antimicrobial agents and on plasmid pTet profiles. Antimicrobials used in this study were: amoxicillin/clavulanic acid, ciprofloxacin, erythromycin, tetracycline and trimethoprim/sulfamethoxazole. Among the isolates studied, 91.7% were resistant to one or more antimicrobial agent. The highest level of resistance for the whole test group was to trimethoprim/sulfamethoxazole (57.6%), followed by ciprofloxacin (44.2%) and tetracycline (20%). All isolates were susceptible to amoxicillin/clavulanic acid. Strains isolated from chickens were susceptible to erythromycin. Few erythromycin-resistant strains were isolated from dogs and pigs (5.8%). C. coli strains exhibited a higher antibiotic resistance than C. jejuni strains, excluding resistance to trimethoprim/sulfamethoxazole. The pTet plasmid harboring the tet(O) gene was detected in 14 Campylobacter spp. strains. Our studies demonstrate that the majority (71.4%) of tetracycline-resistant isolates carry a plasmid-borne tet(O) gene, particularly strains for which the minimum inhibitory concentration (MIC) are > or = 256 microg/ml. In conclusion, we have found high-level trimethoprim/sulfamethoxazole, ciprofloxacin and tetracycline resistance in Polish strains isolated from different sources. This study has demonstrated that resistance of Campylobacter species differs depending on both the bacterial species and animal origins. All strains that displayed resistance to four antimicrobial agents were isolated from pigs. Localization of the tet(O) gene on either plasmid or chromosome was not found to be correlated with tetracycline resistance. PMID:20169919

  16. Risk factors for resistance to antimicrobial agents among nursing home residents.

    PubMed

    Loeb, Mark B; Craven, Sharon; McGeer, Allison J; Simor, Andrew E; Bradley, Suzanne F; Low, Donald E; Armstrong-Evans, Maxine; Moss, Lorraine A; Walter, Stephen D

    2003-01-01

    The authors prospectively collected data on exposure to antimicrobial agents and susceptibility patterns among all clinical isolates of bacteria taken from 9,156 residents of 50 nursing homes in Canada and the United States in 1998-1999. Exposure to antimicrobial agents was measured during the 10 weeks prior to detection of targeted resistant bacteria in residents and compared with antibiotic exposure during a 10-week interval in individuals with sensitive organisms. These main effects were adjusted for infection-control and staffing covariates using multiple logistic regression modeling. Increased staffing of nursing homes with registered nurses (adjusted odds ratio (OR) = 0.79 (95% confidence interval (CI): 0.72, 0.87) per registered nurse per 100 resident-days) and use of antibacterial soap (adjusted OR = 0.40, 95% CI: 0.18, 0.90) were associated with reduced risk of methicillin-resistant Staphylococcus aureus in nursing home residents. An increase in the number of hand-washing sinks per 100 residents was shown to reduce the risk of trimethoprim-sulfamethoxazole (TMP/SMX)-resistant Enterobacteriaceae (adjusted OR = 0.94, 95% CI: 0.90, 0.98). Exposure to TMP-SMX and exposure to fluoroquinolones were significant risk factors for isolation of TMP-SMX-resistant Enterobacteriaciae (adjusted OR = 1.14, 95% CI: 1.06, 1.22) and fluoroquinolone-resistant Enterobacteriaciae (adjusted OR = 1.08, 95% CI: 1.04, 1.11), respectively. These findings suggest that increased staffing, more hand-washing sinks, and use of antimicrobial soap may reduce resistance to antimicrobial agents in long-term care facilities. PMID:12505889

  17. Sensitivity of bacterial biofilms and planktonic cells to a new antimicrobial agent, Oxsil 320N.

    PubMed

    Surdeau, N; Laurent-Maquin, D; Bouthors, S; Gellé, M P

    2006-04-01

    The effective concentrations of disinfectants were determined for planktonic bacteria using the norms EN 1040 and NF T 72-150. This concentration corresponds to biocide efficacy after 5 min of contact, followed by neutralization. However, micro-organisms often colonize a substratum and form microcolonies or biofilms where they are enclosed in exopolymer matrices. Biofilms are commonly resistant to a broad range of antimicrobial agents, and resistance mechanisms involve exopolymer matrices, changes in gene expression and metabolic alterations. Due to these different resistance mechanisms, it is difficult to select and titrate antimicrobial agents to be effective against biofilms. In this context, SODIFRA developed a new disinfectant, Oxsil 320N (French patent 94 15 193). Oxsil 320N is an association of three active principles: hydrogen peroxide, acetic acid/peracetic acid and silver. This biocide was tested on planktonic bacteria and on 24-h biofilms formed on AISI 304 stainless steel surfaces. The effective concentration of Oxsil 320N was also determined on biofilms using SODIFRA recommendations (without neutralization of the biocide). Data showed that the antimicrobial efficacy measured on planktonic bacteria is not a reliable indicator of performance when biofilm is present. When biofilms were exposed to Oxsil 320N, the concentration needed to achieve a 10(5)-fold decrease in concentration was 10 times higher than that for bacterial suspensions (0.313% Oxsil 320N). An effective concentration of Oxsil 320N of 3.13% was required. PMID:16478644

  18. 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

    2016-01-01

    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. PMID:27007362

  19. Multidrug resistance genes in staphylococci from animals that confer resistance to critically and highly important antimicrobial agents in human medicine.

    PubMed

    Wendlandt, Sarah; Shen, Jianzhong; Kadlec, Kristina; Wang, Yang; Li, Beibei; Zhang, Wan-Jiang; Feßler, Andrea T; Wu, Congming; Schwarz, Stefan

    2015-01-01

    Most antimicrobial resistance genes known so far to occur in staphylococci of animal origin confer resistance to a specific class of antimicrobial agents or to selected members within such a class. However, there are also a few examples of multidrug resistance (MDR) genes that confer resistance to antimicrobial agents of different classes by either target site methylation or active efflux via ATP-binding cassette (ABC) transporters. The present review provides an overview of these MDR genes with particular reference to those genes involved in resistance to critically or highly important antimicrobial agents used in human and veterinary medicine. Moreover, their location on mobile genetic elements and colocated resistance genes, which may play a role in coselection and persistence of the MDR genes, are addressed. PMID:25455417

  20. Discovery of novel berberine imidazoles as safe antimicrobial agents by down regulating ROS generation.

    PubMed

    Wen, Si-Qi; Jeyakkumar, Ponmani; Avula, Srinivasa Rao; Zhang, Ling; Zhou, Cheng-He

    2016-06-15

    A series of novel berberine-based imidazole derivatives as new type of antimicrobial agents were developed and characterized. Most of them gave good antibacterial activity toward the Gram-positive and negative bacteria. Noticeably, imidazolyl berberine 3a exhibited low MIC value of 1μg/mL against Eberthella typhosa, which was even superior to reference drugs berberine, chloromycin and norfloxacin. The cell toxicity and ROS generation assay indicated that compound 3a showed low cell toxicity. The interactive investigation by UV-vis spectroscopic method revealed that compound 3a could effectively intercalate into calf thymus DNA to form 3a-DNA complex which might further block DNA replication to exert the powerful antimicrobial activities. The binding behavior of compound 3a to DNA topoisomerase IB revealed that hydrogen bonds and electrostatic interactions played important roles in the association of compound 3a with DNA topoisomerase IB. PMID:27156777

  1. 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. PMID:22416718

  2. 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

  3. 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. PMID:22029522

  4. In Vitro Effects of Antimicrobial Agents on Planktonic and Biofilm Forms of Staphylococcus lugdunensis Clinical Isolates▿

    PubMed Central

    Frank, Kristi L.; Reichert, Emily J.; Piper, Kerryl E.; Patel, Robin

    2007-01-01

    Staphylococcus lugdunensis is an atypically virulent coagulase-negative staphylococcal species associated with acute and destructive infections that often resemble Staphylococcus aureus infections. Several types of infection caused by S. lugdunensis (e.g., native valve endocarditis, prosthetic joint infection, and intravascular catheter infection) are associated with biofilm formation, which may lead to an inability to eradicate the infection due to the intrinsic nature of biofilms to resist high levels of antibiotics. In this study, planktonic MICs and MBCs and biofilm bactericidal concentrations of 10 antistaphylococcal antimicrobial agents were measured for 15 S. lugdunensis isolates collected from patients with endocarditis, medical device infections, or skin and soft tissue infections. Planktonic isolates were susceptible to all agents studied, but biofilms were resistant to high concentrations of most of the drugs. However, moxifloxacin was able to kill 73% of isolates growing in biofilms at ≤0.5 μg/ml. Relative to the effect on cell density, subinhibitory concentrations of nafcillin substantially stimulated biofilm formation of most isolates, whereas tetracycline and linezolid significantly decreased biofilm formation in 93 and 80% of isolates, respectively. An unexpected outcome of MBC testing was the observation that vancomycin was not bactericidal against 93% of S. lugdunensis isolates, suggesting widespread vancomycin tolerance in this species. These data provide insights into the response of S. lugdunensis isolates when challenged with various levels of antimicrobial agents in clinical use. PMID:17158933

  5. In vitro activities of antimicrobial agents against clinical isolates of Flavimonas oryzihabitans obtained from patients with cancer.

    PubMed

    Rolston, K V; Ho, D H; LeBlanc, B; Bodey, G P

    1993-11-01

    We evaluated the in vitro activities of 21 different antimicrobial agents against nine clinical isolates of Flavimonas oryzihabitans obtained from patients with cancer. The organisms were susceptible to most agents commonly used for the empiric therapy (aminoglycosides, ureidopenicillins, extended-spectrum cephalosporins, monobactams, and carbapenems) and prevention of infections (quinolones and trimethoprim-sulfamethoxazole) in this patient population. PMID:8285645

  6. Development of a rapid multiplexed assay for the direct screening of antimicrobial residues in raw milk.

    PubMed

    McGrath, Terry F; McClintock, Laura; Dunn, John S; Husar, Gregory M; Lochhead, Michael J; Sarver, Ronald W; Klein, Frank E; Rice, Jennifer A; Campbell, Katrina; Elliott, Christopher T

    2015-06-01

    Antimicrobial residues found to be present in milk can have both health and economic impacts. For these reasons, the widespread routine testing of milk is required. Due to delays with sample handling and test scheduling, laboratory-based tests are not always suited for making decisions about raw material intake and product release, especially when samples require shipping to a central testing facility. Therefore, rapid on-site screening tests that can produce results within a matter of minutes are required to facilitate rapid intake and product release processes. Such tests must be simple for use by non-technical staff. There is increasing momentum towards the development and implementation of multiplexing tests that can detect a range of important antimicrobial residues simultaneously. A simple in situ multiplexed planar waveguide device that can simultaneously detect chloramphenicol, streptomycin and desfuroylceftiofur in raw dairy milk, without sample preparation, has been developed. Samples are simply mixed with antibody prior to an aliquot being passed through the detection cartridge for 5 min before reading on a field-deployable portable instrument. Multiplexed calibration curves were produced in both buffer and raw milk. Buffer curves, for chloramphenicol, streptomycin and desfuroylceftiofur, showed linear ranges (inhibitory concentration (IC)20-IC80) of 0.1-0.9, 3-129 and 12-26 ng/ml, whilst linear range in milk was 0.13-0.74, 11-376 and 2-12 ng/ml, respectively, thus meeting European legislated concentration requirements for both chloramphenicol and streptomycin, in milk, without the need for any sample preparation. Desfuroylceftiofur-contaminated samples require only simple sample dilution to bring positive samples within the range of quantification. Assay repeatability and reproducibility were lower than 12 coefficient of variation (%CV), whilst blank raw milk samples (n = 9) showed repeatability ranging between 4.2 and 8.1%CV when measured on all

  7. A general approach to describe the antimicrobial agent release from highly swellable films intended for food packaging applications.

    PubMed

    Buonocore, G G; Del Nobile, M A; Panizza, A; Corbo, M R; Nicolais, L

    2003-06-01

    A mathematical model able to describe the release kinetics of antimicrobial agents from crosslinked polyvinylalcohol (PVOH) into water is presented. The model was developed by taking into account the diffusion of water molecules into the polymeric film, the counter-diffusion of the incorporated antimicrobial agent from the film into water, and the polymeric matrix swelling kinetic. To validate the model the water sorption kinetics as well as the release kinetics of three antimicrobial agents (i.e., lysozyme, nisin and sodium benzoate, all approved to be used in contact with food) were determined at ambient temperature (25 degrees C). The three investigated active agents were entrapped in four films of PVOH with a different degree of crosslink. The model was successfully used to fit all the above sets of data, corroborating the validity of the hypothesis made to derive it. PMID:12767710

  8. Efflux pump inhibitors (EPIs) as new antimicrobial agents against Pseudomonas aeruginosa

    PubMed Central

    Askoura, Momen; Mottawea, Walid; Abujamel, Turki; Taher, Ibrahim

    2011-01-01

    Pseudomonas aeruginosa is an opportunistic human pathogen and one of the leading causes of nosocomial infections worldwide. The difficulty in treatment of pseudomonas infections arises from being multidrug resistant (MDR) and exhibits resistance to most antimicrobial agents due to the expression of different mechanisms overcoming their effects. Of these resistance mechanisms, the active efflux pumps in Pseudomonas aeruginosa that belong to the resistance nodulation division (RND) plays a very important role in extruding the antibiotics outside the bacterial cells providing a protective means against their antibacterial activity. Beside its role against the antimicrobial agents, these pumps can extrude biocides, detergents, and other metabolic inhibitors. It is clear that efflux pumps can be targets for new antimicrobial agents. Peptidomimetic compounds such as phenylalanine arginyl β-naphthylamide (PAβN) have been introduced as efflux pump inhibitors (EPIs); their mechanism of action is through competitive inhibition with antibiotics on the efflux pump resulting in increased intracellular concentration of antibiotic, hence, restoring its antibacterial activity. The advantage of EPIs is the difficulty to develop bacterial resistance against them, but the disadvantage is their toxic property hindering their clinical application. The structure activity relationship of these compounds showed other derivatives from PAβN that are higher in their activity with higher solubility in biological fluids and decreased toxicity level. This raises further questions on how can we compact Pseudomonas infections. Of particular importance, the recent resurgence in the use of older antibiotics such as polymyxins and probably applying stricter control measures in order to prevent their spread in clinical sittings. PMID:21594004

  9. 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

  10. 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. PMID:26950031

  11. pH and Antimicrobial Activity of Portland Cement Associated with Different Radiopacifying Agents

    PubMed Central

    Guerreiro-Tanomaru, Juliane Maria; Cornélio, Ana Lívia G.; Andolfatto, Carolina; Salles, Loise P.; Tanomaru-Filho, Mário

    2012-01-01

    Objective. The aim of this study was to evaluate the antimicrobial activity and pH changes induced by Portland cement (PC) alone and in association with radiopacifiers. Methods. The materials tested were pure PC, PC + bismuth oxide, PC + zirconium oxide, PC + calcium tungstate, and zinc oxide and eugenol cement (ZOE). Antimicrobial activity was evaluated by agar diffusion test using the following strains: Micrococcus luteus, Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans. After 24 hours of incubation at 37°C, inhibition of bacterial growth was observed and measured. For pH analysis, material samples (n = 10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 12, 24, 48, and 72 hours, the pH of the solutions was determined using a pH meter. Results. All microbial species were inhibited by the cements evaluated. All materials composed of PC with radiopacifying agents promoted pH increase similar to pure Portland cement. ZOE had the lowest pH values throughout all experimental periods. Conclusions. All Portland cement-based materials with the addition of different radiopacifiers (bismuth oxide, calcium tungstate, and zirconium oxide) presented antimicrobial activity and pH similar to pure Portland cement. PMID:23119173

  12. pH and Antimicrobial Activity of Portland Cement Associated with Different Radiopacifying Agents.

    PubMed

    Guerreiro-Tanomaru, Juliane Maria; Cornélio, Ana Lívia G; Andolfatto, Carolina; Salles, Loise P; Tanomaru-Filho, Mário

    2012-01-01

    Objective. The aim of this study was to evaluate the antimicrobial activity and pH changes induced by Portland cement (PC) alone and in association with radiopacifiers. Methods. The materials tested were pure PC, PC + bismuth oxide, PC + zirconium oxide, PC + calcium tungstate, and zinc oxide and eugenol cement (ZOE). Antimicrobial activity was evaluated by agar diffusion test using the following strains: Micrococcus luteus, Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans. After 24 hours of incubation at 37°C, inhibition of bacterial growth was observed and measured. For pH analysis, material samples (n = 10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 12, 24, 48, and 72 hours, the pH of the solutions was determined using a pH meter. Results. All microbial species were inhibited by the cements evaluated. All materials composed of PC with radiopacifying agents promoted pH increase similar to pure Portland cement. ZOE had the lowest pH values throughout all experimental periods. Conclusions. All Portland cement-based materials with the addition of different radiopacifiers (bismuth oxide, calcium tungstate, and zirconium oxide) presented antimicrobial activity and pH similar to pure Portland cement. PMID:23119173

  13. Co-grafting of antiadhesive and antimicrobial agents onto UV-micropatterned copper surfaces.

    PubMed

    Peyre, Jessie; Humblot, Vincent; Méthivier, Christophe; Berjeaud, Jean-Marc; Pradier, Claire-Marie

    2015-12-01

    Adhesion of proteins and bacteria was reduced by a factor close to one order of magnitude, and adhered bacteria were dramatically damaged on copper surfaces by grafting a PEG-modified PMMA-based (polymethyl methacrylate) copolymer together with an antimicrobial peptide. To obtain PEG and a peptide grafted together on the surface, a UV sensitive copolymer (containing PMMA, PEG and a UV sensitive reagent) was primary synthesized and deposited. After selective UV irradiation of this copolymer layer, an antimicrobial peptide, Magainin I, was grafted onto freed-polymer coated-copper surface via a spacer molecule (a mercapto carboxylic acid). The functionalization was characterized at each step by Polarization Modulation Reflection Absorption Infrared Spectroscopy (PM-RAIRS). The antiadhesive properties of the copolymer layer and antibacterial activity of the anchored Magainin I, were individually tested toward adsorption of bovine serum albumin (BSA) proteins, and against Gram positive bacteria, Listeria ivanovii, respectively. The results revealed that adhesion of both proteins and bacteria has been considerably reduced; moreover, the peptide still displays some antimicrobial activity after grafting. This work gives new ideas and perspectives to elaborate complex surface coatings where several agents are needed like for anti-biofilm or sensing applications. PMID:26613864

  14. 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). PMID:15910225

  15. [The immunomodulatory and anti-inflammatory properties of different antimicrobial agents].

    PubMed

    Guz, Katarzyna; Bugla-Płoskońska, Gabriela

    2007-01-01

    One of the major achievements in modern medicine has been the development of research into antimicrobial agents. These drugs are now widely used in the treatment of human and animal infectious diseases caused by bacterial pathogens. However, some antibacterial agents, mainly macrolides, tetracyclines, and sulfonamides, have both anti-inflammatory and immunomodalotory properties. They can down-regulate prolonged inflammation, increase mucus clearance, prevent bacterial biofilm formation, and stimulate or impair the activation of the host immune system. It is possible that these drugs are able in modify phagocyte activity by altering their functions (chemotaxis, phagocytosis, oxidative burst, bacterial killing, and cytokine production). In addition, some antibiotics influence the biology of bacteria; they alter their metabolism, morphology, and antigenicity and inhibit the production of various virulence factors. The immunomodulatory and anti-inflammatory properties of antibiotics can occasionally be therapeutically useful in the treatment of chronic, noninfectious disorders, such as rheumatism, asthma, and other immunological diseases. PMID:18097341

  16. Antibacterial and residual antimicrobial activities against Enterococcus faecalis biofilm: A comparison between EDTA, chlorhexidine, cetrimide, MTAD and QMix.

    PubMed

    Zhang, Rui; Chen, Min; Lu, Yan; Guo, Xiangjun; Qiao, Feng; Wu, Ligeng

    2015-01-01

    We compared the antibacterial and residual antimicrobial activities of five root canal irrigants (17% EDTA,2% chlorhexidine,0.2% cetrimide, MTAD, and QMix) in a model of Enterococcus faecalis biofilm formation. Sixty dentin blocks with 3-week E. faecalis biofilm were divided into six equal groups and flushed with irrigant for 2 min or left untreated. A blank control group was also established. Antibacterial activities of the irrigants were evaluated by counting colony forming units. To test residual antimicrobial activities, 280 dentin blocks were divided into seven equal groups and flushed with irrigant for 2 min or left untreated and then incubated with E. faecalis suspension for 48 h, or used as a blank. No bacteria were observed in the blank control group. The number of viable E. faecalis was significantly fewer in the irrigant-treated groups compared with the untreated control (P < 0.05). Among the five irrigants, QMix had the strongest antibacterial activity. Residual antimicrobial activities of CHX were significantly higher at 12 h, 24 h and 36 h compared to untreated control (P < 0.05). All five root canal irrigants were effective to some extent against E. faecalis, but QMix and CHX had the strongest, and CHX the longest (up to 36 h), antimicrobial activity. PMID:26245711

  17. Antibacterial and residual antimicrobial activities against Enterococcus faecalis biofilm: A comparison between EDTA, chlorhexidine, cetrimide, MTAD and QMix

    PubMed Central

    Zhang, Rui; Chen, Min; Lu, Yan; Guo, Xiangjun; Qiao, Feng; Wu, Ligeng

    2015-01-01

    We compared the antibacterial and residual antimicrobial activities of five root canal irrigants (17% EDTA,2% chlorhexidine,0.2% cetrimide, MTAD, and QMix) in a model of Enterococcus faecalis biofilm formation. Sixty dentin blocks with 3-week E. faecalis biofilm were divided into six equal groups and flushed with irrigant for 2 min or left untreated. A blank control group was also established. Antibacterial activities of the irrigants were evaluated by counting colony forming units. To test residual antimicrobial activities, 280 dentin blocks were divided into seven equal groups and flushed with irrigant for 2 min or left untreated and then incubated with E. faecalis suspension for 48 h, or used as a blank. No bacteria were observed in the blank control group. The number of viable E. faecalis was significantly fewer in the irrigant-treated groups compared with the untreated control (P < 0.05). Among the five irrigants, QMix had the strongest antibacterial activity. Residual antimicrobial activities of CHX were significantly higher at 12 h, 24 h and 36 h compared to untreated control (P < 0.05). All five root canal irrigants were effective to some extent against E. faecalis, but QMix and CHX had the strongest, and CHX the longest (up to 36 h), antimicrobial activity. PMID:26245711

  18. Antibacterial and residual antimicrobial activities against Enterococcus faecalis biofilm: A comparison between EDTA, chlorhexidine, cetrimide, MTAD and QMix

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Chen, Min; Lu, Yan; Guo, Xiangjun; Qiao, Feng; Wu, Ligeng

    2015-08-01

    We compared the antibacterial and residual antimicrobial activities of five root canal irrigants (17% EDTA,2% chlorhexidine,0.2% cetrimide, MTAD, and QMix) in a model of Enterococcus faecalis biofilm formation. Sixty dentin blocks with 3-week E. faecalis biofilm were divided into six equal groups and flushed with irrigant for 2 min or left untreated. A blank control group was also established. Antibacterial activities of the irrigants were evaluated by counting colony forming units. To test residual antimicrobial activities, 280 dentin blocks were divided into seven equal groups and flushed with irrigant for 2 min or left untreated and then incubated with E. faecalis suspension for 48 h, or used as a blank. No bacteria were observed in the blank control group. The number of viable E. faecalis was significantly fewer in the irrigant-treated groups compared with the untreated control (P < 0.05). Among the five irrigants, QMix had the strongest antibacterial activity. Residual antimicrobial activities of CHX were significantly higher at 12 h, 24 h and 36 h compared to untreated control (P < 0.05). All five root canal irrigants were effective to some extent against E. faecalis, but QMix and CHX had the strongest, and CHX the longest (up to 36 h), antimicrobial activity.

  19. 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

  20. Trends in the resistance to antimicrobial agents of Streptococcus suis isolates from Denmark and Sweden.

    PubMed

    Aarestrup, F M; Rasmussen, S R; Artursson, K; Jensen, N E

    1998-08-28

    This study was conducted to determine the MIC values of historical and contemporary Streptoccocus suis (serotypes 2 and 7) from Denmark and S. suis (serotype 2) from Sweden. A total of 52 isolates originating from 1967 through 1981 and 156 isolates from 1992 through 1997 in Denmark and 13 isolates from Sweden were examined for their MICs against 20 different antimicrobial agents. Most antimicrobials were active against most isolates. A frequent occurrence of resistance to sulphamethoxazole was observed, with most resistance among historic isolates of serotype 7 and least resistance among isolates from Sweden. A large number of the isolates was resistant to macrolides. However, all historic serotype 2 isolates from Denmark were susceptible, whereas 20.4% of the contemporary isolates were resistant. Among serotype 7 isolates 23.3% of the historic isolates were resistant to macrolides, whereas resistance was found in 44.8% of the contemporary isolates. All isolates from Sweden were susceptible to macrolides. Time-associated frequency of resistance to tetracycline was also found. Only a single historic isolate of serotype 2 was resistant to tetracycline, whereas 43.9% of the contemporary serotype 2 isolates and 15.5% of the contemporary serotype 7 isolates were resistant. Only one (7.7%) of the isolates from Sweden was resistant. The differences in resistance between historic and contemporary isolates from Denmark were statistically significant. This study demonstrated a significant serotype-associated difference in the susceptibility to macrolides and tetracycline and demonstrated that an increase in resistance among S. suis isolates has taken place during the last 15 years to the two most commonly used antimicrobial agents (tylosin and tetracycline) in pig production in Denmark. PMID:9810623

  1. Detection of Salmonella spp., Candida albicans, Aspergillus spp., and Antimicrobial Residues in Raw and Processed Cow Milk from Selected Smallholder Farms of Zimbabwe

    PubMed Central

    Mhone, Tryness Anastazia; Matope, Gift; Saidi, Petronella Tapiwa

    2012-01-01

    A cross-sectional study was conducted to detect the presence of Salmonella spp., Candida albicans, Aspergillus spp., and antimicrobial residues in raw milk (n = 120) and processed cow milk (n = 20) from smallholder dairy farms from three sites in Zimbabwe. Culture and isolation of Salmonella spp., C. albicans, and Aspergillus spp. were performed using selective media, while antimicrobial residues were detected by a dye reduction test. No Salmonella, but C. albicans (17.5%; 21/120), Aspergillus spp. (0.8%; 1/120), and antimicrobial residues (2.5%; 3/120) were detected from raw milk. C. albicans was isolated from all three sites, while Aspergillus spp. and antimicrobial residues were detected from sites 1 and 3, respectively. From processed milk, only C. albicans (5%) was isolated while Aspergillus spp. and antimicrobial residues were not detected. These results suggested low prevalence of Salmonella spp. and Aspergillus spp. and a relatively high prevalence of C. albicans in raw milk from the smallholder farms. The potential public health risks of C. albicans and the detected antimicrobial residues need to be considered. Thus, educating farmers on improving milking hygiene and storage of milk and establishing programmes for monitoring antimicrobial residues may help to improve the safety of milk from smallholder farms. PMID:23050199

  2. Novel antimicrobial peptides that exhibit activity against select agents and other drug resistant bacteria.

    PubMed

    Venugopal, Divakaramenon; Klapper, David; Srouji, Antoine H; Bhonsle, Jayendra B; Borschel, Richard; Mueller, Allen; Russell, Amanda L; Williams, Brittany C; Hicks, Rickey P

    2010-07-15

    One of the greatest challenges facing modern medicine is the evolution of drug resistant strains of bacteria. In addition to traditional methods of exposure to traditional bacterial organisms there is a growing concerned of the use of bacteria as bio-terrorism agents. To counter the evolution of drug resistant and potential bio-terrorism bacterial agents new antibiotic drugs must be developed. One potential source of new therapeutic agents that act via a novel mechanism of action are natural and synthetic antimicrobial peptides (AMPs). In our laboratories we have developed a series of AMPs incorporating the un-natural amino acids Tic-Oic to impart organism selectivity and potency while increasing metabolic stability. Herein the in vitro activity of these peptides, including ten new compounds, against eight potential bio-terrorism bacterial agents and three other bacterial strains is presented and discussed. These peptides exhibit a wide range of organism potency and selectivity. Calcein fluorescence leakage and circular dichroism studies were conducted to confirm that these peptides interact with zwitterionic and anionic liposomes. PMID:20558071

  3. A central composite rotatable design (CCRD) approach to study the combined effect of antimicrobial agents against bacterial pathogens.

    PubMed

    Santos, Fernanda Godoy; Mendonça, Layanne Andrade; Mantovani, Hilário Cuquetto

    2015-09-01

    The combination of antimicrobial agents has been proposed as a therapeutic strategy to control bacterial diseases and to reduce the emergence of antibiotic-resistant strains in clinical environments. In this study, the interaction between the lantibiotic bovicin HC5 with chloramphenicol, gentamicin, nisin, lysostaphin and hydrogen peroxide against Staphylococcus aureus O46 was evaluated by MIC assays. The central composite rotatable design (CCRD), a robust and economic statistical design, was used to combine concentration levels of different antimicrobials agents with distinct mechanisms of action and the presence of significant interactions among the antimicrobials was determined by regression analysis. According to the adjusted model, there were no significant interactions between bovicin HC5 and gentamicin, lysostaphin, nisin or hydrogen peroxide. However, bovicin HC5 showed a significant interaction (P < 0.02) with chloramphenicol. This is the first study applying the CCRD approach to evaluate the combined effect of antimicrobials against S. aureus. Based on our results, this approach is an effective strategy to determine synergistic interactions between antimicrobial agents applied in human and veterinary medicine against bacterial pathogens. PMID:26081601

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

    PubMed Central

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

    2015-01-01

    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

  5. Effect of Antimicrobial Agents on MinD Protein Oscillations in E. coli Bacterial Cells

    NASA Astrophysics Data System (ADS)

    Kelly, Corey; Giuliani, Maximiliano; Dutcher, John

    2012-02-01

    The pole-to-pole oscillation of MinD proteins in E. coli cells determines the location of the division septum, and is integral to healthy cell division. It has been shown previously that the MinD oscillation period is approximately 40 s for healthy cells [1] but is strongly dependant on environmental factors such as temperature, which may place stress on the cell [2,3]. We use a strain of E. coli in which the MinD proteins are tagged with green fluorescent protein (GFP), allowing fluorescence visualization of the MinD oscillation. We use high-resolution total internal reflection fluorescence (TIRF) microscopy and a custom, temperature controlled flow cell to observe the effect of exposure to antimicrobial agents on the MinD oscillation period and, more generally, to analyze the time variation of the spatial distribution of the MinD proteins within the cells. These measurements provide insight into the mechanism of antimicrobial action. [1] Raskin, D.M.; de Boer, P. (1999) Proc. Natl. Acad. Sci. 96: 4971-4976. [2] Touhami, A.; Jericho, M; Rutenberg, A. (2006) J. Bacteriol. 188: 7661-7667. [3] Downing, B.; Rutenberg, A.; Touhami, A.; Jericho, M. (2009) PLoS ONE 4: e7285.

  6. Phyllanthus wightianus Müll. Arg.: a potential source for natural antimicrobial agents.

    PubMed

    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

  7. [Resistance to antimicrobial agents, hemolytic activity and plasmids in Aeromonas species].

    PubMed

    Morita, K; Watanabe, N; Kanamori, M

    1990-06-01

    A total of 174 Aeromonas isolates consisting of 100 strains from patients with diarrhea being mainly overseas travellers nd healthy subjects, and 74 strains from environmental sources including foods, fish, fresh water, sea water and river soil collected in the area of Tokyo Metropolis and Kanagawa Prefecture was examined for the antimicrobial resistance, presence of plasmids and hemolytic activity. Almost all the isolates (99.4%) were resistant to aminobenzyl penicillin. The isolation frequency of chloramphenicol- or tetracycline-resistant strain was low. Most environmental isolates of A. hydrophila were resistant to multiple antimicrobial agents. Thirty-seven percent of environmental isolates and 39% of human fecal ones carried plasmids. In environmental isolates, seven A. hydrophila and three A. sobria strains carried 63- to 150-kilobase pair (kb) conjugative R plasmids. Two A. hydrophila strains from both the healthy subject and domestic case with diarrhea carried 58- to 90-kb conjugative R plasmids, respectively. None of the isolates from the feces of overseas traveller's diarrhea carried the plasmid. Irrespective of the sources. A. hydrophila showed the highest hemolytic activity among three Aeromonas species. Eighty percent or more of A. hydrophila isolates were of hemolysin positive. The hemolytic titer of A. hydrophila strains from human feces was higher than that of the strains from environmental sources. PMID:2401817

  8. Comparative in vitro activity of faropenem and 11 other antimicrobial agents against 250 invasive Streptococcus pneumoniae isolates from France.

    PubMed

    Decousser, J W; Pina, P; Picot, F; Allouch, P Y

    2003-09-01

    The aim of the study presented here was to evaluate the in vitro activity of faropenem, a new member of the penem class intended for oral administration, compared with 11 other antimicrobial agents against a large number of Streptococcus pneumoniae strains isolated from adults and children with bloodstream infections in France. The minimum inhibitory concentration of faropenem against 90% of the pediatric strains tested was generally one to two dilutions lower than the most potent beta-lactam agents (i.e., 0.5 micro g/ml for faropenem vs. 1 for amoxicillin, 1 for cefotaxime and 0.5 micro g/ml for ceftriaxone). Against the adult strains, only moxifloxacin had a MIC(90) value similar to faropenem (i.e., 0.25 micro g/ml for both agents). Faropenem seems to be a promising antimicrobial agent for the treatment of adult and pediatric Streptococcus pneumoniae infections. PMID:12942341

  9. Effects of subtherapeutic administration of antimicrobial agents to beef cattle on the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter hyointestinalis.

    PubMed

    Inglis, G D; McAllister, T A; Busz, H W; Yanke, L J; Morck, D W; Olson, M E; Read, R R

    2005-07-01

    The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (> or =94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of

  10. Effects of Subtherapeutic Administration of Antimicrobial Agents to Beef Cattle on the Prevalence of Antimicrobial Resistance in Campylobacter jejuni and Campylobacter hyointestinalis†

    PubMed Central

    Inglis, G. D.; McAllister, T. A.; Busz, H. W.; Yanke, L. J.; Morck, D. W.; Olson, M. E.; Read, R. R.

    2005-01-01

    The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (≥94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a

  11. DECOMPOSITION SUPPRESSION OF RAYON BY SURFACE COATING USING ANTIMICROBIAL AGENTS AND POVAL

    NASA Astrophysics Data System (ADS)

    Nittami, Tadashi; Murata, Ryota; Nakamura, Kenji; Matsumoto, Kanji; Nakamura, Kazuho

    The authors examined whether decomposition of rayon in environment is suppressed by coating it with antimicrobial agent DC5700 and poval (PVA). When the rayon samples coated with DC5700 were decomposed in activated sludge or bark compost toge ther with non-coated samples, the coated samples needed longer time for the decomposition comparing to the non-coated samples under the environmental condition whose water content is 56% or less. Moreov er, PVA coating together with DC5700 further extended the decomposition time of rayon samples under the condition whose water content is 40% or less. The dyeing test of DC5700 using bromphenol blue indicated that PVA coating together with DC5700 prevented DC5700 from removing from the rayon su rface under the low-water-con tent condition and thus the double coating sample was decomposed slowly.

  12. Contribution of Cell Surface Hydrophobicity in the Resistance of Staphylococcus aureus against Antimicrobial Agents.

    PubMed

    Lather, Puja; Mohanty, A K; Jha, Pankaj; Garsa, Anita Kumari

    2016-01-01

    Staphylococcus aureus is found in a wide variety of habitats, including human skin, where many strains are commensals that may be clinically significant or contaminants of food. To determine the physiological characteristics of resistant strain of Staphylococcus aureus against pediocin, a class IIa bacteriocin, a resistant strain was compared with wild type in order to investigate the contribution of hydrophobicity to this resistance. Additional clumping of resistant strain relative to wild type in light microscopy was considered as an elementary evidence of resistance attainment. A delay in log phase attainment was observed in resistant strain compared to the wild type strain. A significant increase in cell surface hydrophobicity was detected for resistant strain in both hexadecane and xylene indicating the contribution of cell surface hydrophobicity as adaptive reaction against antimicrobial agents. PMID:26966577

  13. Sparfloxacin-metal complexes as antifungal agents - Their synthesis, characterization and antimicrobial activities

    NASA Astrophysics Data System (ADS)

    Sultana, Najma; Arayne, M. Saeed; Gul, Somia; Shamim, Sana

    2010-06-01

    Metal complexes with the third-generation quinolone antibacterial agent sparfloxacin (SPFX) or 5-amino-1-cyclopropyl-7-(cis-3,5-dimethyl-1-piperazinyl)-6,8,di-fluoro-1-4-dihydro-4-oxo-3-quinocarboxylic acid have been synthesized and characterized with physicochemical and spectroscopic techniques such as TLC, IR, NMR and elemental analyses. In these complexes, sparfloxacin acts as bidentate deprotonated ligands bound to the metal through the pyridone oxygen and one carboxylate oxygen. The antimicrobial activity of these complexes has been evaluated against four Gram-positive and seven Gram-negative bacteria. Antifungal activity against five different fungi has been evaluated and compared with reference drug sparfloxacin. Fe 2+-SPFX and Cd 2+-SPFX complexes showed remarkable potency as compared to the parent drug.

  14. Contribution of Cell Surface Hydrophobicity in the Resistance of Staphylococcus aureus against Antimicrobial Agents

    PubMed Central

    Lather, Puja; Mohanty, A. K.; Jha, Pankaj; Garsa, Anita Kumari

    2016-01-01

    Staphylococcus aureus is found in a wide variety of habitats, including human skin, where many strains are commensals that may be clinically significant or contaminants of food. To determine the physiological characteristics of resistant strain of Staphylococcus aureus against pediocin, a class IIa bacteriocin, a resistant strain was compared with wild type in order to investigate the contribution of hydrophobicity to this resistance. Additional clumping of resistant strain relative to wild type in light microscopy was considered as an elementary evidence of resistance attainment. A delay in log phase attainment was observed in resistant strain compared to the wild type strain. A significant increase in cell surface hydrophobicity was detected for resistant strain in both hexadecane and xylene indicating the contribution of cell surface hydrophobicity as adaptive reaction against antimicrobial agents. PMID:26966577

  15. Formation of complexes of antimicrobial agent norfloxacin with antitumor antibiotics of anthracycline series

    NASA Astrophysics Data System (ADS)

    Evstigneev, M. P.; Rybakova, K. A.; Davies, D. B.

    2007-05-01

    The formation of complexes in solutions of the norfloxacin antimicrobial agent (NOR) with daunomycin (DAU) and nogalamycin (NOG), antitumor anthracycline antibiotics, was studied using 1H NMR spectroscopy. Based on the concentration and temperature dependences of the chemical shifts of the protons of interacting molecules, the equilibrium constants and thermodynamic parameters (enthalpy and entropy) of heteroassociation of the antibiotics were calculated. It was shown that NOR interacts with DAU (NOG) in aqueous solutions forming stacked heterocomplexes with parallel orientation of the molecular chromophores. The conclusion was drawn that such interactions should be taken into account when anthracyclines and quinolones are jointly administered during combined chemotherapy, since they can contribute to the medico-biological synergistic effect of these antibiotics.

  16. In Vitro Model of Colonization Resistance by the Enteric Microbiota: Effects of Antimicrobial Agents Used in Food-Producing Animals▿

    PubMed Central

    Wagner, R. Doug; Johnson, Shemedia J.; Cerniglia, Carl E.

    2008-01-01

    A bioassay was developed to measure the minimum concentration of an antimicrobial drug that disrupts the colonization resistance mediated by model human intestinal microbiota against Salmonella invasion of Caco-2 intestinal cells. The bioassay was used to measure the minimum disruptive concentrations (MDCs) of drugs used in animal agriculture. The MDCs varied from 0.125 μg/ml for some broad-spectrum antimicrobial drugs (e.g., streptomycin) to 16 μg/ml for drugs with limited spectra of antimicrobial activity (e.g., lincomycin). The acceptable daily intake (ADI) residue concentration calculated on the basis of the MDCs were higher for erythromycin, lincomycin, and tylosin than the ADI residue concentrations calculated on the basis of the MICs. The MDC-based ADI values for apramycin, bacitracin, neomycin, novobiocin, penicillin G, streptomycin, tetracycline, and vancomycin were lower than the reported MIC-based ADI values. The effects of antimicrobial drugs at their MDCs on the bacterial composition of the microbiota were observed by denaturing gradient gel electrophoresis of 16S rRNA sequences amplified by PCR. Changes in the population composition of the model colonization resistance microbiota occurred simultaneously with reduced colonization resistance. The results of this study suggest that direct assessment of the effects of antimicrobial drugs on colonization resistance in an in vitro model can be useful in determining ADI values. PMID:18227184

  17. In vitro model of colonization resistance by the enteric microbiota: effects of antimicrobial agents used in food-producing animals.

    PubMed

    Wagner, R Doug; Johnson, Shemedia J; Cerniglia, Carl E

    2008-04-01

    A bioassay was developed to measure the minimum concentration of an antimicrobial drug that disrupts the colonization resistance mediated by model human intestinal microbiota against Salmonella invasion of Caco-2 intestinal cells. The bioassay was used to measure the minimum disruptive concentrations (MDCs) of drugs used in animal agriculture. The MDCs varied from 0.125 microg/ml for some broad-spectrum antimicrobial drugs (e.g., streptomycin) to 16 microg/ml for drugs with limited spectra of antimicrobial activity (e.g., lincomycin). The acceptable daily intake (ADI) residue concentration calculated on the basis of the MDCs were higher for erythromycin, lincomycin, and tylosin than the ADI residue concentrations calculated on the basis of the MICs. The MDC-based ADI values for apramycin, bacitracin, neomycin, novobiocin, penicillin G, streptomycin, tetracycline, and vancomycin were lower than the reported MIC-based ADI values. The effects of antimicrobial drugs at their MDCs on the bacterial composition of the microbiota were observed by denaturing gradient gel electrophoresis of 16S rRNA sequences amplified by PCR. Changes in the population composition of the model colonization resistance microbiota occurred simultaneously with reduced colonization resistance. The results of this study suggest that direct assessment of the effects of antimicrobial drugs on colonization resistance in an in vitro model can be useful in determining ADI values. PMID:18227184

  18. Application of Antimicrobial Agents via Commercial Spray Cabinet To Inactivate Salmonella on Skinless Chicken Meat.

    PubMed

    Hawkins, J L; Vimini, B; Schwarz, J G; Nichols, P; Parveen, S

    2016-04-01

    Salmonella enterica subsp. enterica serovar Typhimurium is a food safety concern for raw poultry products. New and innovative application methods of antimicrobials for the reduction of Salmonella in poultry and poultry products are essential. The aim of this study was to determine the efficacy of three antimicrobial compounds against Salmonella on raw chicken meat when applied individually and in combination using a commercial spray cabinet. Raw chicken thigh meat inoculated with 5 log CFU/g Salmonella Typhimurium ATCC 53647 was passed through a spray cabinet while being sprayed with 5% lauric arginate (LAE), 0.8% vinegar solution (VS), near-neutral electrolyzed water, or deionized water. The following three experiments were carried out: (i) exposure times of 0, 15, 30, 45, and 60 s, (ii) storage at 4°C for 0, 1, 2, and 3 days after a 60-s exposure, and (iii) a combination of treatment with LAE and VS followed by storage at 4°C for 0, 1, 2, and 3 days. Analysis of variance and the Tukey test were used to determine mean significant differences (P < 0.05). The experiment was carried out in duplicate for each replicate (n = 3 × 2). In comparing individual antimicrobials, the 60-s treatment time resulted in the greatest reduction of Salmonella Typhimurium, with LAE achieving the greatest reduction (2.07 log), followed by VS, near-neutral electrolyzed water, and deionized water (0.63, 0.56, and 0.53 log, respectively). After 3 days of storage, LAE significantly (P < 0.05) reduced Salmonella Typhimurium, by 1.28 log. The combination of VS and then LAE resulted in a significantly (P < 0.05) greater reduction than using LAE followed by VS (1.61 and 0.93 log, respectively). The results of this study suggest that LAE is a viable compound to reduce Salmonella Typhimurium on raw chicken meat and that the order of application of antimicrobial agents plays a vital role. PMID:27052860

  19. Edible Coating as Carrier of Antimicrobial Agents to Extend the Shelf Life of Fresh-Cut Apples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edible coatings with antimicrobial agents provide a novel way to improve the safety and shelf-life of fresh-cut fruit. The effect of lemongrass, oregano oil and vanillin, incorporated in apple puree-alginate edible coatings, on the shelf-life of fresh-cut Fuji apples, was investigated. Coated appl...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  1. In Vitro Activities of Linezolid Combined with Other Antimicrobial Agents against Staphylococci, Enterococci, Pneumococci, and Selected Gram-Negative Organisms

    PubMed Central

    Sweeney, Michael T.; Zurenko, Gary E.

    2003-01-01

    The activities of linezolid, an oxazolidinone antibacterial agent active against gram-positive organisms, alone and in combination with 35 antimicrobial agents were tested in vitro against methicillin-sensitive (n = 1 to 2 strains) and methicillin-resistant (n = 8 to 10) Staphylococcus aureus strains; vancomycin-sensitive (n = 6) and vancomycin-resistant (n = 6 to 8) Enterococcus faecalis strains; vancomycin-sensitive (n = 5) and vancomycin-resistant (n = 6) Enterococcus faecium strains; penicillin-sensitive (n = 2 to 5), penicillin-intermediate (n = 5 to 6), and penicillin-resistant (n = 5 to 6) Streptococcus pneumoniae strains; Escherichia coli (n = 6); and Klebsiella pneumoniae (n = 6). The fractional inhibitory concentration indices of linezolid in combination with other antimicrobial agents for the organisms tested were generated on checkerboard broth microdilution plates prepared by a semiautomated method. Of 1,380 organism-drug combinations, 1,369 (99.2%) combinations of linezolid with 28 antimicrobial drugs were indifferent, 9 combinations (0.65%) of linezolid with 6 drugs (amoxicillin, erythromycin, imipenem, sparfloxacin, teicoplanin, and tetracycline) were synergistic, and 2 combinations (0.15%) of linezolid with 2 drugs (ofloxacin and sparfloxacin) were antagonistic. Overall, the in vitro data demonstrated that linezolid combined with other antimicrobial agents primarily produces an indifferent response, with infrequent occurrences of synergism and antagonism. PMID:12760865

  2. In vitro activities of polycationic peptides alone and in combination with clinically used antimicrobial agents against Rhodococcus equi.

    PubMed

    Giacometti, A; Cirioni, O; Ancarani, F; Del Prete, M S; Fortuna, M; Scalise, G

    1999-08-01

    The in vitro activities of magainin II, nisin, and ranalexin alone and in combination with other antimicrobial agents against six clinical isolates of Rhodococcus equi were investigated by MIC and time-kill studies. All isolates were more susceptible to nisin. A positive interaction was observed when the peptides were combined with ampicillin, ceftriaxone, rifabutin, rifampin, azithromycin, clarithromycin, and vancomycin. PMID:10428947

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. Comparison of different agar diffusion methods for the detection of residues in the kidneys of pigs treated with antimicrobial drugs.

    PubMed

    Korkeala, H; Sorvettula, O; Mäki-Petäys, O; Hirn, J

    1983-01-01

    Residue analyses of the kidneys of twenty-six pigs treated with various antimicrobial drugs 20 h before slaughter and of eleven untreated pigs were performed. The effects of storage temperature of the kidneys, and of sampling location, on the residue analysis were also studied. No method alone was sufficient for the detection of residues. Oxytetracycline residues could be detected at pH 6, dihydrostreptomycin residues at pH 8, and sulphonamide residues if trimethoprim was present in the medium. Chloramphenicol, penicillin G procaine, tylosin and lincomycin residues were not detectable with the methods used. The concentration of ampicillin decreased during the storage of samples at +4°C. Most methods also yielded zones of inhibition for the frozen kidneys from untreated pigs. It seems necessary to use agar media of two different pH values: the addition of trimethoprim to the medium is also needed. The use of fresh pig kidneys, and samples containing both kidney medulla and kidney cortex, is recommended in residue analysis. PMID:22055926

  6. The detection limits of antimicrobial agents in cow's milk by a simple Yoghurt Culture Test.

    PubMed

    Mohsenzadeh, M; Bahrainipour, A

    2008-09-15

    The aim of this study was to study performance of Yoghurt Culture Test (YCT) in the detection of antimicrobial residues in milk. For this purpose, the sensitivity of YCT for 15 antibiotics were determined. For each drug, 8 concentrations were tested. The detection limits of YCT at 2.5 h and 4 h incubation were determined (microg kg(-1)): 15 and 37.5, penicillin G; 4 and 5, ampicillin; 5 and 7.5, amoxycillin; 100 and 200, cephalexin; 80 and 100, cefazoline; 100 and 200, oxytetracycline; 500 and 100, chlortetracycline; 100 and 200, tetracycline; 150 and 200, doxycycline; 200 and 400, sulphadimidine; 500 and 1000, gentamycin; 1000 and 1500, spectinomycin; 400 and 500, erythromycin; 50 and 100, tylosin; 5000 and 10000, chloramphenicol. The YCT detection limits at 2.5 h incubation for ampicillin, cephalexin, tetracycline, oxytetracycline and tylosin are similar to those obtained as Maximum Residue Limit (MRL) according to Regulation 2377/90 EEC as set out by the European Union. In addition the detection limits of YCT for some antibiotics were lower than some of microbial inhibitor test. PMID:19137842

  7. Distribution of drug-resistant bacteria and rational use of clinical antimicrobial agents

    PubMed Central

    ZHOU, CHENLIANG; CHEN, XIAOBING; WU, LIWEN; QU, JING

    2016-01-01

    Open wound may lead to infection in patients. Due to overuse of medication, certain bacteria have become resistant to drugs currently available. The aim of the present study was to provide a guide to ameliorate the appropriate and rational use of clinical antimicrobial agents by analyzing the distribution of drug-resistant pathogenic bacteria in patients. Between October 2013 and January 2015, 126 patients were selected at the Department of Orthopedics. Wound secretion samples were collected, and the pathogen bacteria isolated and identified. Identification was performed using an automated identification instrument and the Kirby-Bauer antibiotic method was used to evaluate the bacterial resistance. Of the 126 patients, 118 patients were infected (infection rate, 93.65%). Additionally, 47 strains of gram-positive pathogenic bacteria (39.83%) and 71 strains of pathogenic-gram negative bacteria (60.17%) were identified. The bacteria were most likely to be resistant to penicillin while sensitive to vancomycin and imipenem. Some bacteria were resistant to several antibacterial agents. The results showed that existing risk factors at the Department of Orthopedics were complex and any non-standard procedures were able to cause bacterial infection. There were obvious dissimilarities among infectious bacteria with regard to their sensitivity to various antibacterial agents. Manipulation techniques during the treatment process were performed in a sterile manner and the use of antibacterial agents was required to be strictly in accordance with the results of drug sensitivity tests to provide effective etiologic information and a treatment plan for clinical trials and to reduce the risk of infection by multi-resistant bacteria. PMID:27313667

  8. Susceptibility of bacterial etiological agents to commonly-used antimicrobial agents in children with sepsis at the Tamale Teaching Hospital

    PubMed Central

    2013-01-01

    Background Bloodstream infections in neonates and infants are life-threatening emergencies. Identification of the common bacteria causing such infections and their susceptibility patterns will provide necessary information for timely intervention. This study is aimed at determining the susceptibilities of bacterial etiological agents to commonly-used antimicrobial agents for empirical treatment of suspected bacterial septicaemia in children. Methods This is a hospital based retrospective analysis of blood cultures from infants to children up to 14 years of age with preliminary diagnosis of sepsis and admitted to the Neonatal Intensive Care Unit (NICU) and Paediatric Wards of the Teaching Hospital Tamale from July 2011 to January 2012. Results Out of 331 blood specimens cultured, the prevalence of confirmed bacterial sepsis was 25.9% (86/331). Point prevalence for confirmed cases from NICU was 44.4% (28/63) and 21.6% (58/268) from the Paediatric ward. Gram positive cocci (GPC) were the predominant isolates with Coagulase positive (32.2%) and Coagulase-negative (28.7%) Staphylococci accounting for 60.9% of the total isolates. Gram negative rods (GNR) comprised 39.1% of all isolates with Klebsiella, E.coli and Salmonella being the most common organisms isolated. Klebsiella was the most frequent GNR from the NICU and Salmonella typhi was predominantly isolated from the paediatric ward. Acinetobacter showed 100.0% susceptibility to Ceftriaxone and Cefotaxime but was resistant (100.0%) to Ampicillin, Tetracycline and Cotrimoxazole. Escherichia coli and Klebsiella were 80.0% and 91.0% susceptible to Ceftriaxone and Cefotaxime respectively. Klebsiella species showed 8.3% susceptibility to Tetracycline but was resistant to Ampicillin and Cotrimoxazole. Escherichia coli showed 40.0% susceptibility to Ampicillin, Chloramphenicol and Cotrimoxazole; 20.0% susceptibility to Tetracycline and 80.0% susceptible to Gentamicin and Cefuroxime. Coagulase negative Staphylococci was

  9. 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

  10. Assessment of the California mastitis test usage in smallholder dairy herds and risk of violative antimicrobial residues.

    PubMed

    Shitandi, Anakalo; Kihumbu, Gathoni

    2004-03-01

    This study evaluated how predictive the California Mastitis Test (CMT) is for sub-clinical mastitis under tropical smallholder dairy production conditions in Kenya. It intended to establish whether the CMT usage could be contributing to misdiagnosis and consequent mistreatment with animal drugs resulting in residue problems. Milk samples (n = 239) were aseptically collected from lactating cows in the Rift Valley of Kenya and tested using the CMT, somatic cell counts (SCC) and bacterial culture. The samples were also screened for violative drug residues using the commercial delvo test and compared to the milks mastitic status for possible association. There was a numerical but non-significant (p > 0.05) difference evident in the frequencies observed using the three different mastitis indicators. The prevalent bacterial species isolated from mammary glands with subclinical mastitis were Staphylococcus aureus (45.6%), coagulase-negative Staphylococci (13.0%), Streptococci (11.7%) and Escherichia coli 5.9%. There was an overall poor but significant (p < 0.05) correlation between the CMT and the violative antimicrobial residues in samples from all quarters, infected and non-infected respectively. The results suggest that the CMT use amongst the smallholder dairy sector as a mastitic indicator may not be a risk factor in violative antimicrobial residues problems in milk. PMID:15028880

  11. 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.

  12. In-vitro activity of cationic peptides alone and in combination with clinically used antimicrobial agents against Pseudomonas aeruginosa.

    PubMed

    Giacometti, A; Cirioni, O; Barchiesi, F; Fortuna, M; Scalise, G

    1999-11-01

    The in-vitro activity of cecropin P1, indolicidin, magainin II, nisin and ranalexin alone and in combination with nine clinically used antimicrobial agents was investigated against a control strain, Pseudomonas aeruginosa ATCC 27853 and 40 clinical isolates of P. aeruginosa. Antimicrobial activities were measured by MIC, MBC and viable count. In the combination study, the clinically used antibiotics were used at concentrations close to their mean serum level in humans in order to establish the clinical relevance of the results. To select peptide-resistant mutants, P. aeruginosa ATCC 27853 was treated with consecutive cycles of exposure to each peptide at 1 x MIC. The peptides had a varied range of inhibitory values: all isolates were more susceptible to cecropin P1, while ranalexin showed the lowest activity. Nevertheless, synergy was observed when the peptides were combined with polymyxin E and clarithromycin. Consecutive exposures to each peptide at 1 x MIC resulted in the selection of stable resistant mutants. Cationic peptides might be valuable as new antimicrobial agents. Our findings show that they are effective against P. aeruginosa, and that their activity is enhanced when they are combined with clinically used antimicrobial agents, particularly with polymyxin E and clarithromycin. PMID:10552980

  13. ['In vitro' activity of different antimicrobial agents on Gram-negative nonfermentative bacilli, excluding Pseudomonas aeruginosa and Acinetobacter spp].

    PubMed

    Vay, C A; Almuzara, M N; Rodríguez, C H; Pugliese, M L; Lorenzo Barba, F; Mattera, J C; Famiglietti, A M R

    2005-01-01

    Gram-negative nonfermentative bacilli (NFB) are widely spread in the environment. Besides of difficulties for identification, they often have a marked multiresistance to antimicrobial agents, including those active against Pseudomonas aeruginosa. The objective of this study was to evaluate the 'in vitro' activity of different antimicrobial agents on 177 gram-negative nonfermentative bacilli isolates (excluding Pseudomonas aeruginosa and Acinetobacter spp.) isolated from clinical specimens. Minimum inhibitory concentrations (MIC) were determined according to the Mueller Hinton agar dilution method against the following antibacterial agents: ampicillin, piperacillin, piperacillin-tazobactam, sulbactam, cefoperazone, cefoperazone-sulbactam, ceftazidime, cefepime, aztreonam, imipenem, meropenem, colistin, gentamicin, amikacin, trimethoprim-sulfamethoxazole, chloramphenicol, erythromycin, rifampin, norfloxacin, ciprofloxacin and minocycline. Seven isolates: Sphingobacterium multivorum (2), Sphingobacteriumspiritivorum (1), Empedobacterbrevis (1), Weeksella virosa (1), Bergeyella zoohelcum (1) and Oligella urethralis (1), were tested for amoxicillin-clavulanic acid and ampicillin-sulbactam susceptibility, and susceptibility to cefoperazone or sulbactam was not determined. Multiresistance was generally found in Stenotrophomonas maltophilia, Burkholderia cepacia, Chryseobacterium spp., Myroides spp., Achromobacter xylosoxidans, and Ochrobactrum anthropi isolates. On the other hand, Pseudomonas stutzeri, Shewanella putrefaciens-algae, Sphingomonas paucimobilis, and Pseudomonas oryzihabitans, Bergeyella zoohelcum, Weeksella virosa and Oligella urethralis were widely susceptible to the antibacterial agents tested. As a result of the wide variation in antimicrobial susceptibility shown by different species, a test on susceptibility to different antibacterial agents is essential in order to select an adequate therapy. The marked multiresistance evidenced by some species

  14. 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

  15. 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

  16. Pharmacodynamics of Antimicrobials against Mycoplasma mycoides mycoides Small Colony, the Causative Agent of Contagious Bovine Pleuropneumonia

    PubMed Central

    Mitchell, John D.; McKellar, Quintin A.; McKeever, Declan J.

    2012-01-01

    Background Mycoplasma mycoides subspecies mycoides Small Colony (MmmSC) is the causative agent of Contagious Bovine Pleuropneumonia (CBPP), a disease of substantial economic importance in sub-Saharan Africa. Failure of vaccination to curtail spread of this disease has led to calls for evaluation of the role of antimicrobials in CBPP control. Three major classes of antimicrobial are effective against mycoplasmas, namely tetracyclines, fluoroquinolones and macrolides. Therefore, the objectives of this study were to determine the effector kinetics of oxytetracycline, danofloxacin and tulathromycin against two MmmSC field strains in artificial medium and adult bovine serum. Methods Minimum inhibitory concentrations (MIC) were determined for oxytetracycline, danofloxacin and tulathromycin against MmmSC strains B237 and Tan8 using a macrodilution technique, and time-kill curves were constructed for various multiples of the MIC over a 24 hour period in artificial medium and serum. Data were fitted to sigmoid Emax models to obtain 24 hour-area under curve/MIC ratios for mycoplasmastasis and, where appropriate, for mycoplasmacidal activity and virtual mycoplasmal elimination. Results Minimum inhibitory concentrations against B237 were 20-fold higher, 2-fold higher and approximately 330-fold lower in serum than in artificial medium for oxytetracycline, danofloxacin and tulathromycin, respectively. Such differences were mirrored in experiments using Tan8. Oxytetracycline was mycoplasmastatic against both strains in both matrices. Danofloxacin elicited mycoplasmacidal activity against B237 and virtual elimination of Tan8; similar maximum antimycoplasmal effects were observed in artificial medium and serum. Tulathromycin effected virtual elimination of B237 but was mycoplasmastatic against Tan8 in artificial medium. However, this drug was mycoplasmastatic against both strains in the more physiologically relevant matrix of serum. Conclusions Oxytetracycline, danofloxacin and

  17. Inactivation of Salmonella Typhimurium in orange juice containing antimicrobial agents by pulsed electric field.

    PubMed

    Liang, Ziwei; Mittal, Gauri S; Griffiths, Mansel W

    2002-07-01

    Combinations of different hurdles, including moderately high temperatures (<60 degrees C), antimicrobial compounds, and pulsed electric field (PEF) treatment, to reduce Salmonella in pasteurized and freshly squeezed orange juices (with and without pulp) were explored. Populations of Salmonella Typhimurium were found to decrease with an increase in pulse number and treatment temperature. At a field strength of 90 kV/cm, a pulse number of 20, and a temperature of 45 degrees C, PEF treatment did not have a notable effect on cell viability or injury. At and above 46 degrees C, however, cell death and injury were greatly increased. Salmonella numbers were reduced by 5.9 log cycles in freshly squeezed orange juice (without pulp) treated at 90 kV/cm, 50 pulses, and 55 degrees C. When PEF treatment was carried out in the presence of nisin (100 U/ml of orange juice), lysozyme (2,400 U/ml), or a mixture of nisin (27.5 U/ml) and lysozyme (690 U/ml), cell viability loss was increased by an additional 0.04 to 2.75 log cycles. The combination of nisin and lysozyme had a more pronounced bactericidal effect than did either nisin or lysozyme alone. An additional Salmonella count reduction of at least 1.37 log cycles was achieved when the two antimicrobial agents were used in combination. No significant difference (P > 0.05) in cell death was attained by lowering the pH value; only cell injury increased. Inactivation by PEF was significantly more extensive (P < 0.05) in pasteurized orange juice than in freshly squeezed orange juice under the same treatment conditions. This increase might be due to the effect of the chemical composition of the juices. PMID:12117238

  18. Comparison of Wipe Materials and Wetting Agents for Pesticide Residue Collection from Hard Surfaces

    EPA Science Inventory

    Different wipe materials and wetting agents have been used to collect pesticide residues from surfaces, but little is known about their comparability. To inform the selection of a wipe for the National Children's Study, the analytical feasibility, collection efficiency, and preci...

  19. Nitrite Reductase from Pseudomonas aeruginosa Released by Antimicrobial Agents and Complement Induces Interleukin-8 Production in Bronchial Epithelial Cells

    PubMed Central

    Sar, Borann; Oishi, Kazunori; Wada, Akihiro; Hirayama, Toshiya; Matsushima, Kouji; Nagatake, Tsuyoshi

    1999-01-01

    We have recently reported that nitrite reductase, a bifunctional enzyme located in the periplasmic space of Pseudomonas aeruginosa, could induce interleukin-8 (IL-8) generation in a variety of respiratory cells, including bronchial epithelial cells (K. Oishi et al. Infect. Immun. 65:2648–2655, 1997). In this report, we examined the mode of nitrite reductase (PNR) release from a serum-sensitive strain of live P. aeruginosa cells during in vitro treatment with four different antimicrobial agents or human complement. Bacterial killing of P. aeruginosa by antimicrobial agents induced PNR release and mediated IL-8 production in human bronchial epithelial (BET-1A) cells. Among these agents, imipenem demonstrated rapid killing of P. aeruginosa as well as rapid release of PNR and resulted in the highest IL-8 production. Complement-mediated killing of P. aeruginosa was also associated with PNR release and enhanced IL-8 production. The immunoprecipitates of the aliquots of bacterial culture containing imipenem or complement with anti-PNR immunoglobulin G (IgG) induced a twofold-higher IL-8 production than did the immunoprecipitates of the aliquots of bacterial culture with a control IgG. These pieces of evidence confirmed that PNR released in the aliquots of bacterial culture was responsible for IL-8 production in the BET-1A cells. Furthermore, the culture supernatants of the BET-1A cells stimulated with aliquots of bacterial culture containing antimicrobial agents or complement similarly mediated neutrophil migration in vitro. These data support the possibility that a potent inducer of IL-8, PNR, could be released from P. aeruginosa after exposure to antimicrobial agents or complement and contributes to neutrophil migration in the airways during bronchopulmonary infections with P. aeruginosa. PMID:10103183

  20. Antimicrobials

    PubMed Central

    Murphy, Eileen F.; Clarke, Siobhan F.; Marques, Tatiana M.; Hill, Colin; Stanton, Catherine; Ross, R. Paul; O’Doherty, Robert M.; Shanahan, Fergus; Cotter, Paul D.

    2013-01-01

    Obesity is associated with a number of serious health consequences, including type 2 diabetes, cardiovascular disease and a variety of cancers among others and has been repeatedly shown to be associated with a higher risk of mortality. The relatively recent discovery that the composition and metabolic activity of the gut microbiota may affect the risk of developing obesity and related disorders has led to an explosion of interest in this distinct research field. A corollary of these findings would suggest that modulation of gut microbial populations can have beneficial effects with respect to controlling obesity. In this addendum, we summarize our recent data, showing that therapeutic manipulation of the microbiota using different antimicrobial strategies may be a useful approach for the management of obesity and metabolic conditions. In addition, we will explore some of the mechanisms that may contribute to microbiota-induced susceptibility to obesity and metabolic diseases. PMID:23018760

  1. Expression and purification of cyto-insectotoxin (Cit1a) using silkworm larvae targeting for an antimicrobial therapeutic agent.

    PubMed

    Ali, M P; Yoshimatsu, Katsuhiko; Suzuki, Tomohiro; Kato, Tatsuya; Park, Enoch Y

    2014-08-01

    Antimicrobial peptides (AMPs), both synthetic and from natural sources, have raised interest recently as potential alternatives to antibiotics. Cyto-insectotoxin (Cit1a) is a 69-amino-acid antimicrobial peptide isolated from the venom of the central Asian spider Lachesana tarabaevi. The synthetic gene Cit1a fused with the enhanced green fluorescent protein (EGFP) gene was expressed as the EGFP-Cit1a fusion protein using a cysteine protease-deleted Bombyx mori nucleopolyhedrovirus (BmNPV-CP(-)) bacmid in silkworm larva and pupa. The antimicrobial effect of the purified protein was assayed using disk diffusion and broth microdilution methods. The minimum inhibitory concentration of EGFP-Cit1a was also measured against several bacterial strains and showed similar antimicrobial activity to that of the synthetic Cit1a reported earlier. The EGFP-Cit1a fusion protein showed antibiotic activity toward gram-positive and gram-negative bacteria at the micromolar concentration level. These results show that active Cit1a can be produced and purified in silkworm, although this peptide is insecticidal. This study demonstrates the potential of active Cit1a purified from silkworms to use as an antimicrobial agent. PMID:24728600

  2. Short communication: Streptococcus species isolated from mastitis milk samples in Germany and their resistance to antimicrobial agents.

    PubMed

    Minst, K; Märtlbauer, E; Miller, T; Meyer, C

    2012-12-01

    Mastitis is one of the most frequent infectious diseases in dairy cattle and is a reason for antimicrobial drug usage in dairy cows. The bacteria involved in bovine mastitis are mainly Streptococcus spp., Staphylococcus spp., and coliforms. The aim of this study was to determine antimicrobial resistance among Streptococcus spp. isolated from bovine mastitis milk. Antimicrobial resistance in Strep. uberis (n=227), Strep. dysgalactiae (n=49), and Strep. agalactiae (n=3) was determined for 9 antimicrobial agents using the broth microdilution method in accordance with Clinical and Laboratory Standards Institute recommendations. Of all Streptococcus spp., 13% were multidrug resistant. The rate of multidrug resistance was higher among Strep. uberis (15%) than among Strep. dysgalactiae (6%) and Strep. agalactiae (0%). Resistance to tetracycline was the most common, followed by resistance to erythromycin, pirlimycin, and gentamicin. Resistance rates were higher on farms with more than 80 cows compared with those with fewer than 20 cows. β-Lactams should remain the drugs of choice in the treatment of streptococcal mastitis. The slightly elevated minimum inhibitory concentrations determined for these antibiotics may indicate, however, the emergence of resistant streptococci. To identify such changes in susceptibility as early as possible, antimicrobial resistance in streptococci should be surveyed regularly. PMID:22999286

  3. Immune mediators of sea-cucumber Holothuria tubulosa (Echinodermata) as source of novel antimicrobial and anti-staphylococcal biofilm agents

    PubMed Central

    2013-01-01

    The present study aims to investigate coelomocytes, immune mediators cells in the echinoderm Holothuria tubulosa, as an unusual source of antimicrobial and antibiofilm agents. The activity of the 5kDa peptide fraction of the cytosol from H. tubulosa coelomocytes (5-HCC) was tested against a reference group of Gram-negative and Gram-positive human pathogens. Minimal inhibitory concentrations (MICs) ranging from 125 to 500 mg/ml were determined against tested strains. The observed biological activity of 5-HCC could be due to two novel peptides, identified by capillary RP-HPLC/nESI-MS/MS, which present the common chemical-physical characteristics of antimicrobial peptides. Such peptides were chemically synthesized and their antimicrobial activity was tested. The synthetic peptides showed broad-spectrum activity at 12.5 mg/ml against the majority of the tested Gram-positive and Gram-negative strains, and they were also able to inhibit biofilm formation in a significant percentage at a concentration of 3.1 mg/ml against staphylococcal and Pseudomonas aeruginosa strains. The immune mediators in H. tubulosa are a source of novel antimicrobial peptides for the development of new agents against biofilm bacterial communities that are often intrinsically resistant to conventional antibiotics. PMID:23800329

  4. The Antimicrobial Properties of Cedar Leaf (Thuja plicata) Oil; A Safe and Efficient Decontamination Agent for Buildings

    PubMed Central

    Hudson, James; Kuo, Michael; Vimalanathan, Selvarani

    2011-01-01

    Cedar leaf oil (CLO), derived from the Western red cedar, Thuja plicata, was evaluated as a safe and acceptable broad spectrum antimicrobial agent, with a view to its potential applications in buildings, including the alleviation of sick building syndrome. Various Gram-positive and Gram-negative human bacteria, and two fungal organisms, all known to be common environmental sources of potential infection, were selected and tested quantitatively, and all of them were found to be susceptible to CLO liquid and vapor. Bacterial spores and Aspergillus niger were sensitive, although less so than the vegetative bacteria. Similar tests with cultured human lung cells showed that continuous exposure to CLO vapor for at least 60 minutes was not toxic to the cells. Based on these results, CLO shows promise as a prospective safe, green, broad-spectrum anti-microbial agent for decontamination of buildings. PMID:22408584

  5. Tolerance to antimicrobial agents and persistence of Escherichia coli and cyanobacteria.

    PubMed

    Samuilov, V D; Bulakhov, A V; Kiselevsky, D B; Kuznetsova, Yu E; Molchanova, D V; Sinitsyn, S V; Shestak, A A

    2008-07-01

    Bacterial persistence is the tolerance of a small part of a cell population to bactericidal agents, which is attained by a suppression of important cell functions and subsequent deceleration or cessation of cell division. The growth rate is the decisive factor in the transition of the cells to the persister state. A comparative study of quickly growing Escherichia coli K-12 strain MC 4100 and cyanobacteria Synechocystis sp. PCC 6803 and Anabaena variabilis ATCC 29413 growing slowly was performed. The cyanobacterial cells, like E. coli cells, differed in sensitivity to antimicrobial substances depending on the growth phase. Carbenicillin inhibiting the synthesis of peptidoglycan, a component of the bacterial cell wall, and lincomycin inhibiting the protein synthesis gave rise to nucleoid decay in cells from exponential cultures of Synechocystis 6803 and did not influence the nucleoids in cells from stationary cultures. Carbenicillin suppressed the growth of exponential cultures and had no effect on cyanobacterial stationary cultures. A suppression of Synechocystis 6803 growth in the exponential phase by lincomycin was stronger than in the stationary phase. Similar data were obtained with cyanobacterial cells under the action of H2O2 or menadione, an inducer of reactive oxygen species production. Slowly growing cyanobacteria were similar to quickly growing E. coli in their characteristics. Persistence is a characteristic feature of cyanobacteria. PMID:18707592

  6. Potential of Submergedly Cultivated Mycelia of Ganoderma spp. as Antioxidant and Antimicrobial Agents.

    PubMed

    Ćilerdžić, Jasmina; Stajic, Mirjana; Vukojevic, Jelena

    2016-01-01

    The study aimed to evaluate the antiradical and antimicrobial (antibacterial and antifungal) potentials of ethanol mycelial extracts of selected Ganoderma species and strains and to define interand intraspecies diversity among Ganoderma species and strains. Ganoderma lucidum strains were good DPPH• scavengers (neutralizing up to 57.12% radicals), contrary to G. applanatum (20.35%) and G. carnosum (17.04%). High correlations between the activities and contents of total phenols in the extracts showed that these compounds were carriers of the activity. Results obtained by both discdiffusion and microdilution methods indicated that the extract of G. lucidum BEOFB 433 was the most potent antibacterial agent that inhibited growth of almost all bacterial species at a concentration of 1.0 mg/mL. Salmonella typhimurium was the most sensitive species to the mycelium extracts. Extracts of G. lucidum BEOFB 431 and BEOFB 434 showed the best antifungal activity since in concentration of 0.5 mg/mL inhibited the growth of Aspergillus glaucus (BEOFB 431) and the growth of A. glaucus and Trichoderma viride (BEOFB 434). Extracts of G. applanatum and G. lucidum BEOFB 431 had the strongest fungicidal effects, with lethal outcomes for A. glaucus and T. viride, respectively, being noted at a concentration of 1.17 mg/mL. Aspergillus niger was proved as the most resistant species. PMID:26420047

  7. Synthesis and Biological Evaluation of 2-Aminobenzamide Derivatives as Antimicrobial Agents: Opening/Closing Pharmacophore Site

    PubMed Central

    Mabkhot, Yahia N.; Al-Majid, Abdullah M.; Barakat, Assem; Al-Showiman, Salim S.; Al-Har, Munirah S.; Radi, Smaail; Naseer, Muhammad Moazzam; Hadda, Taibi B.

    2014-01-01

    A series of new 2-aminobenzamide derivatives (1–10) has been synthesized in good to excellent yields by adopting both conventional and/or a time-efficient microwave assisted methodologies starting from isatoic anhydride (ISA) and characterized on the basis of their physical, spectral and microanalytical data. Selected compounds of this series were then tested against various bacterial (Bacillus subtilis (RCMB 000107) and Staphylococcus aureus (RCMB 000106). Pseudomonas aeruginosa (RCMB 000102) and Escherichia coli (RCMB 000103) and fungal strains (Saccharomyces cerevisiae (RCMB 006002), Aspergillus fumigatus (RCMB 002003) and Candida albicans (RCMB 005002) to explore their potential as antimicrobial agents. Compound 5 was found to be the most active compound among those tested, which showed excellent antifungal activity against Aspergillus fumigatus (RCMB 002003) more potent than standard Clotrimazole, and moderate to good antibacterial and antifungal activity against most of the other strains of bacteria and fungi. Furthermore, potential pharmacophore sites were identified and their activity was related with the structures in the solution. PMID:24663060

  8. VINEGAR AS AN ANTIMICROBIAL AGENT FOR CONTROL OF Candida spp. IN COMPLETE DENTURE WEARERS

    PubMed Central

    Pinto, Telma Maria Silva; Neves, Ana Christina Claro; Leão, Mariella Vieira Pereira; Jorge, Antonio Olavo Cardoso

    2008-01-01

    The use of denture is known to increase the carriage of Candida in healthy patients, and the proliferation of Candida albicans strains can be associated with denture-induced stomatitis. The aim of this study was to evaluate the use of vinegar as an antimicrobial agent for control of Candida spp. in complete upper denture wearers. Fifty-five patients were submitted to a detailed clinical interview and oral clinical examination, and were instructed to keep their dentures immersed in a 10% vinegar solution (pH less than 3) overnight for 45 days. Before and after the experimental period, saliva samples were collected for detection of Candida, counting of cfu/mL and identification of species by phenotypical tests (germ tube formation, chlamidoconidia production, and carbohydrate fermentation and assimilation). The results were analyzed using Spearman's correlation and Student's t-test (p≤0.05). Candida yeasts were present in 87.3% of saliva samples before the treatment. A significant reduction was verified in CFU/mL counts of Candida after treatment. A positive correlation between Candida and denture stomatitis was verified, since the decrease of cfu/mL counts was correlated with a reduction in cases of denture stomatitis. Although it was not able to eliminate C. albicans, the immersion of the complete denture in 10% vinegar solution, during the night, reduced the amounts (cfu/mL) of Candida spp. in the saliva and the presence of denture stomatitis in the studied patients. PMID:19082396

  9. 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. PMID:25474066

  10. 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. PMID:11037756

  11. Minimum inhibitory concentrations of 20 antimicrobial agents against Staphylococcus aureus isolated from bovine intramammary infections in Japan.

    PubMed

    Yoshimura, H; Ishimaru, M; Kojima, A

    2002-11-01

    Minimum inhibitory concentrations (MICs) of 20 antimicrobial agents were determined against 51 isolates of Staphylococcus aureus from bovine intramammary infections. Fourteen (27.4%) isolates were resistant to benzylpenicillin, but none of the isolates was resistant to cloxacillin, nafcillin, or cephems. Among aminoglycosides, gentamicin was the most active, with an MIC50 of 0.2 microg/ml, followed by kanamycin, with an MIC50 of 0.78 microg/ml. Five isolates (9.8%) were resistant to dihydrostreptomycin, three isolates (5.9%) to kanamycin and two isolates (3.9%) to gentamicin. Resistance to erythromycin was observed in two isolates (3.9%). Tylosin was less active than erythromycin, with MIC50s of 1.56 microg/ml versus 0.39 microg/ml, but none of the isolates was resistant to this antibiotic. Oxytetracycline MICs were situated in the range of 0.39-1.56 microg/ml for 48 susceptible isolates. Although 19 (37.3%) isolates were resistant to one or more antimicrobial agents, a single resistance pattern was most frequent: benzylpenicillin (12 isolates), dihydrostreptomycin (two isolates) and kanamycin (one isolate). There were no isolates resistant to antimicrobial agents such as methicillin, lincomycin, clindamycin, chloramphenicol, florfenicol and virginiamycin, which have not been approved for use in cattle husbandry in Japan. PMID:12489715

  12. An update discussion on the current assessment of the safety of veterinary antimicrobial drug residues in food with regard to their impact on the human intestinal microbiome.

    PubMed

    Cerniglia, Carl E; Pineiro, Silvia A; Kotarski, Susan F

    2016-05-01

    The human gastrointestinal tract ecosystem consists of complex and diverse microbial communities that have now been collectively termed the intestinal microbiome. Recent scientific breakthroughs and research endeavours have increased our understanding of the important role the intestinal microbiome plays in human health and disease. The use of antimicrobial new animal drugs in food-producing animals may result in the presence of low levels of drug residues in edible foodstuffs. There is concern that antimicrobial new animal drugs in or on animal-derived food products at residue-level concentrations could disrupt the colonization barrier and/or modify the antimicrobial resistance profile of human intestinal bacteria. Therapeutic doses of antimicrobial drugs have been shown to promote shifts in the intestinal microbiome, and these disruptions promote the emergence of antimicrobial-resistant bacteria. To assess the effects of antimicrobial new animal drug residues in food on human intestinal bacteria, many national regulatory agencies and international committees follow a harmonized process, VICH GL36(R), which was issued by a trilateral organization of the European Union, the USA, and Japan called the International Cooperation on Harmonization of Technical Requirements for Veterinary Medicinal Products (VICH). The guidance describes a general approach currently used by national regulatory agencies and international committees to assess the effects of antimicrobial new animal drug residues in animal-derived food on human intestinal bacteria. The purpose of this review is to provide an overview of this current approach as part of the antimicrobial new animal drug approval process in participating countries, give insights on the microbiological endpoints used in this safety evaluation, and discuss the availability of new information. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27443209

  13. Antimicrobial agents from higher plants. The quaternary alkaloids of Ptelea trifoliata.

    PubMed

    Mitscher, L A; Bathala, M S; Clark, G W; Beal, J L

    1975-01-01

    Quaternary alkaloid extracts of Ptelea trifoliata showed potentially interesting antimicrobial activity. Chromatographic examination showed the presence of six components. Of these, choline and O-4-methyl ptelefolinium were known compounds. Rational structures are proposed for the new alkaloids, O-4-methylhydroxyluninium, neohydroxylunine and pteleatinium salts. Pteleatinium salt is responsible for the antimicrobial activity of the extracts of the plant. PMID:1094214

  14. The antimicrobial activity of a dentin conditioner combined with antibacterial agents.

    PubMed

    Botelho, Michael G

    2005-01-01

    Dental hand instruments are not efficient in removing all infected dentin when performing carious removal for minimal intervention techniques. The use of an antibacterial dentin conditioner may therefore be useful when restoring cavities that have residual carious dentin. Antibacterial agents--chlorhexidine hydrochloride, cetylpyridinium chloride, cetrimide, benzaIkonium chloride and sodium hypochlorite, were added either to a dentin conditioner used for glass ionomer cements or distilled water at 1% concentration. Dentin conditioning solutions at pH 2.5, 4.9 and 7.7 were also prepared, along with 1% aqueous thymol. Using an agar diffusion test, 25 microl aliquots were examined for their inhibitory effects on three cariogenic bacteria. After 24 hours, an agar pellet was extracted adjacent to the agar well and placed on a second inoculated agar plate to observe sustained inhibitory effects, after which this procedure was repeated one more time. Antibacterial dentin conditioners showed significant inhibitory effect compared to the control over the three test periods (p<0.016). The combination of dentin conditioners with antibacterial agents significantly reduced the inhibitory effect compared to the antibacterial aqueous solutions (p<0.016). One-percent aqueous thymol showed no inhibitory effect against the test bacteria. The cetrimide-dentin conditioner showed the greatest inhibitory effect against all three test bacteria over the three experimental periods (p<0.016). The inhibitory effect of antibacterial agents was significantly reduced when combined with a dentin conditioner. Only the cetrimide-dentin conditioner combination produced significant inhibitory effects against all three test organisms. PMID:15765961

  15. 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. PMID:22691487

  16. 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. PMID:25269010

  17. Comparison of antimicrobial agents as therapy for experimental endocarditis: caused by methicillin-resistant Staphylococcus aureus.

    PubMed

    Sacar, Mustafa; Sacar, Suzan; Cevahir, Nural; Onem, Gokhan; Teke, Zafer; Asan, Ali; Turgut, Huseyin; Adali, Fahri; Kaleli, Ilknur; Susam, Ibrahim; Yaylali, Yalin Tolga; Baltalarli, Ahmet

    2010-01-01

    We used an experimental rat model to compare the therapeutic efficacy of teicoplanin, linezolid, and quinupristin/dalfopristin with that of vancomycin as standard therapy for infective endocarditis.Aortic endocarditis was induced in rats by insertion of a polyethylene catheter into the left ventricle, followed by intravenous inoculation of 106 colony-forming units of methicillin-resistant Staphylococcus aureus 24 hours later. Forty-eight hours after bacterial challenge, intravenous antibiotic therapies were initiated. There were 6 groups of 8 rats each: uninfected control; infected, untreated control; vancomycin-treated (40 mg/kg twice daily); teicoplanin-treated (20 mg/kg twice daily after a loading dose of 40 mg/kg); linezolid-treated (75 mg/kg 3 times daily for 1 day, then 75 mg/kg twice daily); and quinupristin/dalfopristin-treated (30 mg/kg twice daily and an additional 10 mg/kg dalfopristin infusion over 6 to 12 hr daily). At the end of therapy, the aortic valve vegetations in the drug-treated rats were evaluated microbiologically.Compared with the infected, untreated group, all drug-treated groups had significantly reduced bacterial titers in the vegetations. Vancomycin, teicoplanin, and quinupristin/dalfopristin all effectively reduced the quantitative bacterial cultures of aortic valve vegetations. In addition, there was no significant difference in the comparative efficacy of teicoplanin, linezolid, and quinupristin/dalfopristin. Vancomycin significantly reduced bacterial counts in comparison with linezolid, which was nonetheless also effective.Our experimental model showed that each of the investigated antimicrobial agents was effective in the treatment of infective endocarditis. PMID:20844611

  18. Relative potency estimates of acceptable residues and reentry intervals after nerve agent release.

    PubMed

    Watson, A P; Jones, T D; Adams, J D

    1992-06-01

    In the event of an unplanned release of a chemical warfare agent during any stage of the Chemical Stockpile Disposal Program, the potential exists for off-post contamination of drinking water, forage crops, grains, garden produce, and livestock. The more persistent agents, such as the organophosphate nerve agent VX, pose the greatest human health concern for reentry. A relative potency approach comparing the toxicity of VX to organophosphate insecticide analogues is developed and used to estimate allowable residues for VX in agricultural products and reentry intervals for public access to contaminated areas. Analysis of mammalian LD50 data by all exposure routes indicates that VX is 10(3) to 10(4) times more toxic than most commercially available organophosphate insecticides. Thus, allowable residues of VX could be considered at concentration levels 10(3) to 10(4) lower than those established for certain insecticides by the U.S. EPA. Evaluation of reentry intervals developed for these organophosphate analogues indicate that, if environmental monitoring cannot reliably demonstrate acceptable levels of VX, restricted access to suspect or contaminated areas may be on the order of weeks to months following agent release. Planning for relocation, mass care centers, and quarantine should take this time period into account. PMID:1376237

  19. Relative potency estimates of acceptable residues and reentry intervals after nerve agent release

    SciTech Connect

    Watson, A.P.; Jones, T.D.; Adams, J.D. )

    1992-06-01

    In the event of an unplanned release of a chemical warfare agent during any stage of the Chemical Stockpile Disposal Program, the potential exists for off-post contamination of drinking water, forage crops, grains, garden produce, and livestock. The more persistent agents, such as the organophosphate nerve agent VX, pose the greatest human health concern for reentry. A relative potency approach comparing the toxicity of VX to organophosphate insecticide analogues is developed and used to estimate allowable residues for VX in agricultural products and reentry intervals for public access to contaminated areas. Analysis of mammalian LD50 data by all exposure routes indicates that VX is 10(3) to 10(4) times more toxic than most commercially available organophosphate insecticides. Thus, allowable residues of VX could be considered at concentration levels 10(3) to 10(4) lower than those established for certain insecticides by the U.S. EPA. Evaluation of reentry intervals developed for these organophosphate analogues indicate that, if environmental monitoring cannot reliably demonstrate acceptable levels of VX, restricted access to suspect or contaminated areas may be on the order of weeks to months following agent release. Planning for relocation, mass care centers, and quarantine should take this time period into account.

  20. Antimicrobial factor from Bacillus amyloliquefaciens inhibits Paenibacillus larvae, the causative agent of American foulbrood.

    PubMed

    Benitez, Lisianne Brittes; Velho, Renata Voltolini; de Souza da Motta, Amanda; Segalin, Jéferson; Brandelli, Adriano

    2012-03-01

    Bacillus amyloliquefaciens LBM 5006 produces an antimicrobial factor active against Paenibacillus larvae, a major honeybee pathogen. The antagonistic effect and the mode of action of the antimicrobial factor were investigated. The antibacterial activity was produced starting at mid-logarithmic growth phase, reaching its maximum during the stationary phase. Exposure of cell suspensions of P. larvae to this antimicrobial resulted in loss of cell viability and reduction in optical density associated with cell lysis. Scanning electron microscopy showed damaged cell envelope and loss of protoplasmic material. The antimicrobial factor was stable for up to 80°C, but it was sensitive to proteinase K and trypsin. Mass spectrometry analysis indicates that the antimicrobial activity is associated with iturin-like peptides. The antimicrobial factor from B. amyloliquefaciens LBM 5006 showed a bactericidal effect against P. larvae cells and spores. This is the first report on iturin activity against P. larvae. This antimicrobial presents potential for use in the control of American foulbrood disease. PMID:21858429

  1. 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.

  2. Ecotoxicity and screening level ecotoxicological risk assessment of five antimicrobial agents: triclosan, triclocarban, resorcinol, phenoxyethanol and p-thymol.

    PubMed

    Tamura, Ikumi; Kagota, Kei-Ichiro; Yasuda, Yusuke; Yoneda, Saori; Morita, Junpei; Nakada, Norihide; Kameda, Yutaka; Kimura, Kumiko; Tatarazako, Norihisa; Yamamoto, Hiroshi

    2013-11-01

    Acute and chronic (or sub-chronic) toxicity of five selected antimicrobial agents, including triclosan (TCS), triclocarban (TCC), resorcinol, phenoxyethanol and p-thymol, was investigated using the conventional three-aquatic-organism battery. These compounds are widely used in cosmetics and other personal care products and their ecological risk has recently become a significant concern. As results of toxicity tests, TCS was found to be most strongly toxic for green algae [e.g. 72 h no observed effect concentration (NOEC) of 0.50 µg l(-1) ] among the selected compounds, followed by TCC, while TCC was more toxic or similar to TCS for Daphnia and fish (e.g. Daphnia 8 day NOEC of 1.9 µg l(-1) ). Having compared the predicted no effect concentration (PNEC) determined from the toxicity data with measured environmental concentrations (MEC), the preliminary ecological risk assessment of these five antimicrobials was conducted. The MEC/PNEC ratios of TCS and TCC were over 1 for some monitoring data, especially in urban streams with watershed areas without sewage service coverage, and their potential risk for green algae and Daphnia might be at a level of concern, although the contribution of TCS/TCC on the total toxicity of the those sites needs to be further investigated. For the three other antimicrobials, the maximum MEC/PNEC ratio for resorcinol was 0.1-1, but those for phenoxyethanol and p-thymol were <0.1 and their risk to aquatic organisms is limited, although the additive effects with TCS, TCC and other antimicrobial agents, such as parabens, need to be further examined in future studies. PMID:22806922

  3. Thiazole-based chalcones as potent antimicrobial agents. Synthesis and biological evaluation.

    PubMed

    Liaras, K; Geronikaki, A; Glamočlija, J; Cirić, A; Soković, M

    2011-05-15

    As part of ongoing studies in developing new antimicrobials, we report the synthesis of a new class of structurally novel derivatives, that incorporate two known bioactive structures a thiazole and chalcone, to yield a class of compounds with interesting antimicrobial properties. Evaluation of antibacterial activity showed that almost all the compounds exhibited greater activity than reference drugs and thus could be promising novel drug candidates. PMID:21524583

  4. 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

  5. Comparison of various antimicrobial agents as catheter lock solutions: preference for ethanol in eradication of coagulase-negative staphylococcal biofilms.

    PubMed

    Qu, Yue; Istivan, Taghrid S; Daley, Andrew J; Rouch, Duncan A; Deighton, Margaret A

    2009-04-01

    Coagulase-negative staphylococci (CoNS) are the main causative agents of bacteraemia in infants managed in neonatal intensive care units (NICUs). Intraluminal colonization of long-term central venous catheters by these bacteria and subsequent biofilm formation are the prerequisites of the bloodstream infections acquired in NICUs. The catheter lock technique has been used to treat catheter colonization; however, the optimum choice of antimicrobial agents and their corresponding concentrations and exposure times have not been determined. The effectiveness of catheter lock solutions (CLSs) was assessed by determining the minimal biofilm eradication concentration of antimicrobial agents against CoNS biofilms. Five conventional antibiotics (oxacillin, gentamicin, vancomycin, ciprofloxacin and rifampicin) alone or in combination, as well as ethanol, were evaluated. Ethanol was found to be superior to all of these conventional antibiotics when used as a CLS. A time-kill study and confocal laser scanning microscopy revealed that exposure to 40 % ethanol for 1 h was sufficient to kill CoNS biofilm cells. To our knowledge, this is the first in vitro study to provide solid evidence to support the rationale of using ethanol at low concentrations for a short time as a CLS, instead of using conventional antibiotics at high concentrations for a long period to treat catheter-related bloodstream infections. PMID:19273639

  6. Comparative in vitro activity of 16 antimicrobial agents against Actinobacillus pleuropneumoniae.

    PubMed

    Yoshimura, H; Takagi, M; Ishimura, M; Endoh, Y S

    2002-01-01

    Sixteen antimicrobial agents were tested for their activity against 68 isolates of Actinobacillus pleuropneumoniae by determining the minimum inhibitory concentrations (MICs). Ceftiofur and the fluoroquinolones danofloxacin and enrofloxacin were the most active compounds, with a MIC for 90% of the isolates (MIC90) of (0.05 microg/ml. The MIC90 values of benzylpenicillin, amoxicillin and aspoxicillin were 0.78 units/ml, 0.39 microg/ml and < or = 0.05 microg/ml, respectively. Three isolates (4.4%) were resistant to penicillins, but aspoxicillin was as active as ceftiofur against the susceptible isolates, with MICs of < or = 0.05 microg/ml for all isolates. Resistance to oxytetracycline, chloramphenicol and thiamphenicol occurred in 22 (32.4%), 14 (20.6%) and 15 (22.1%) of the isolates, respectively. Doxycycline was more active than oxytetracycline, with a MIC90 of 1.56 microg/ml as against 25 microg/ml. Florfenicol was not only as active as thiamphenicol, with a MIC for 50% of the isolates (MIC50) of 0.39 microg/ml, but also active against thiamphenicol-resistant isolates. All the isolates were susceptible to florfenicol. All the isolates were also susceptible to gentamicin, spectinomycin, tilmicosin, colistin and tiamulin. Of these, spectinomycin was the least active, with a MIC50 of 25 microg/ml, followed by tiamulin, with a MIC50 of 6.25 microg/ml. Of the 68 isolates tested, 49 (72.0%) were of serotype 2; 14 (20.5%) were of serotype 1; 2 each (3.0%) were of serotypes 5 and 6; and one was of serotype 7. Of the isolates, 23 (33.8%) were resistant to one or more of the major antibiotics. Antibiotic resistance was found only infrequently among serotype 2, with 5 (10.2%) of 49 isolates being resistant to chloramphenicol and/or oxytetracycline, while it occurred in 18 (94.7%) of the 19 isolates of other serotypes. PMID:11860083

  7. Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin

    PubMed Central

    ALCÂNTARA, Cristiane S.; de MACÊDO, Allana F.C.; GURGEL, Bruno C.V.; JORGE, Janaina H.; NEPPELENBROEK, Karin H.; URBAN, Vanessa M.

    2012-01-01

    In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties. Objective This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply). Material and Methods Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37ºC for 48 h. The drug powder concentrations (nystatin 500,000U - G2; nystatin 1,000,000U - G3; miconazole 125 mg - G4; miconazole 250 mg - G5; ketoconazole 100 mg - G6; ketoconazole 200 mg - G7; chlorhexidine diacetate 5% - G8; and 10% chlorhexidine diacetate - G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers' instructions and stored in distilled water at 37ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified. Results No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups. Conclusions Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents. PMID:23329241

  8. Release time of residual oxygen after dental bleaching with 35% hydrogen peroxide: effect of a catalase-based neutralizing agent.

    PubMed

    Guasso, Bárbara; Salomone, Paloma; Nascimento, Paulo Cícero; Pozzobon, Roselaine Terezinha

    2016-01-01

    This article assessed the effect of a catalase-based agent on residual oxygen (O2) release from teeth exposed to 35% hydrogen peroxide (H2O2). The use of the catalase-based neutralizer agent for 2-3 minutes was able to release residual O2 5 days after exposure to a 35% H2O2-based bleaching gel. PMID:27148658

  9. Effect of antimicrobial agents on the production and release of shiga toxin by enterotoxaemic Escherichia coli isolates from pigs.

    PubMed

    Uemura, Ryoko; Sueyoshi, Masuo; Taura, Yasuho; Nagatomo, Hiroshi

    2004-08-01

    Edema disease (ED) of pigs is an enterotoxaemic disease caused by enterotoxaemic Escherichia coli (ETEEC) infection. Antimicrobial therapy for pigs with ED is controversial because it may induce death of sickish piglets. In this study, we investigated the effects in vitro of 7 antimicrobial agents, ampicillin, gentamicin, colistin, bicozamycin, fosfomycin, sulfamethoxazole-trimethoprim and enrofloxacin, on the release and production of shiga toxin (Stx) 2e by ETEEC strains. We found that more Stx 2e accumulated in the bacterial cells than was released into supernatant. Associated with inhibition of cell wall synthesis, the exposure to ampicillin or fosfomycin increased the release of Stx 2e. The production levels of Stx 2e in all antimicrobial-treated cultures were equal to the level in the control or less than in the control. These results suggest that cell wall synthesis inhibitors, such as ampicillin and fosfomycin, may change for the worse in the signs in ETEEC infectious pigs. On the other hand, gentamicin, colistin, bicozamycin and enrofloxacin may be useful for the treatment of pigs with ED. PMID:15353838

  10. 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. PMID:27235621

  11. Exploiting Innate Immune Cell Activation of a Copper-Dependent Antimicrobial Agent during Infection

    PubMed Central

    Festa, Richard A.; Helsel, Marian E.; Franz, Katherine J.; Thiele, Dennis J.

    2014-01-01

    SUMMARY Recalcitrant microbial infections demand new therapeutic options. Here we present an approach that exploits two prongs of the host immune cell antimicrobial response: the oxidative burst and the compartmentalization of copper (Cu) within phagolysosomes. The prochelator QBP is a nontoxic protected form of 8-hydroxyquinoline (8HQ) in which a pinanediol boronic ester blocks metal ion coordination by 8HQ. QBP is deprotected via reactive oxygen species produced by activated macrophages, creating 8HQ and eliciting Cu-dependent killing of the fungal pathogen Cryptococcus neoformans in vitro and in mouse pulmonary infection. 8HQ ionophoric activity increases intracellular Cu, overwhelming the Cu-resistance mechanisms of C. neoformans to elicit fungal killing. The Cu-dependent antimicrobial activity of 8HQ against a spectrum of microbial pathogens suggests that this strategy may have broad utility. The conditional activation of Cu ionophores by innate immune cells intensifies the hostile antimicrobial environment and represents a promising approach to combat infectious disease. PMID:25088681

  12. Dropwort (Filipendula hexapetala Gilib.): potential role as antioxidant and antimicrobial agent

    PubMed Central

    Katanic, Jelena; Mihailovic, Vladimir; Stankovic, Nevena; Boroja, Tatjana; Mladenovic, Milan; Solujic, Slavica; Stankovic, Milan S.; Vrvic, Miroslav M.

    2015-01-01

    The aim of this study was to investigate the antioxidant activity of the methanolic extracts of Filipendula hexapetala Gilib. aerial parts (FHA) and roots (FHR) and their potential in different model systems, as well as antimicrobial activity. According to this, a number of assays were employed to evaluate the antioxidant and antimicrobial potential of F. hexapetala extracts. In addition, the antioxidant activity assays in different model systems were carried out, as well as pH, thermal and gastrointestinal stability studies. The phenolic compounds contents in FHA and FHR were also determined. The results showed that F. hexapetala extracts had considerable antioxidant activity in vitro and a great stability in different conditions. The extracts exhibited antimicrobial activity against most of the tested bacterial and fungal species. Also, the extracts contain high level of phenolic compounds, especially aerial parts extract. PMID:26417349

  13. Novel Antimicrobial Agents: Fluorinated 2-(3-(Benzofuran-2-yl) pyrazol-1-yl)thiazoles

    PubMed Central

    Mohamed, Hanan A.; Abdel-Latif, Ehab; Abdel-Wahab, Bakr F.; Awad, Ghada E. A.

    2013-01-01

    A new series of 2-pyrazolin-1-ylthiazoles 8a–d and 13–16 was synthesized by cyclization of N-thiocarboxamide-2-pyrazoline with different haloketones and 2,3-dichloroquinoxaline. The structures of the new compounds were confirmed by elemental analyses as well as NMR, IR, and mass spectral data. The newly synthesized compounds were evaluated for their antimicrobial activities, and also their minimum inhibitory concentration (MIC) against most of test organisms was performed. Amongst the tested ones, compound 8c displayed excellent antimicrobial activity. PMID:25379293

  14. Synthesis and biological evaluation of 5,7-dihydroxyflavanone derivatives as antimicrobial agents.

    PubMed

    Zhang, Xing; Khalidi, Omar; Kim, So Young; Wang, Ruitong; Schultz, Victor; Cress, Brady F; Gross, Richard A; Koffas, Mattheos A G; Linhardt, Robert J

    2016-07-01

    A series of 5,7-dihydroxyflavanone derivatives were efficiently synthesized. Their antimicrobial efficacy on Gram-negative, Gram-positive bacteria and yeast were evaluated. Among these compounds, most of the halogenated derivatives exhibited the best antimicrobial activity against Gram-positive bacteria, the yeast Saccharomyces cerevisiae, and the Gram-negative bacterium Vibrio cholerae. The cytotoxicities of these compounds were low as evaluated on HepG2 cells using a cell viability assay. This study suggests that halogenated flavanones might represent promising pharmacological candidates for further drug development. PMID:27210435

  15. 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. PMID:25990864

  16. Applications of ZnO nanoflowers as antimicrobial agents for Escherichia coli and enzyme-free glucose sensor.

    PubMed

    Umar, Ahmad; Chauhan, M S; Chauhan, S; Kumar, R; Sharma, P; Tomar, Kirti Janghu; Wahab, R; Al-Hajry, A; Singh, Dilbag

    2013-10-01

    Well-crystalline ZnO nanoflowers were prepared by a facile solution process and their applications as an antimicrobial agent against Escherichia coli and enzyme-free glucose sensor have been studied. The morphological, structural, compositional, and optical properties of ZnO nanoflowers were characterized by various techniques, which confirmed the well-crystalline wurtzite hexagonal phase. The minimum inhibitory concentration of ZnO nanoflowers for inhibiting the growth of Escherichia coli was found to be 25 microg/ml. ZnO nanoflowers were also tested as an efficient electron mediator for the fabrication of highly sensitive non-enzymatic glucose sensor, which exhibited a high sensitivity of -411 microA M(-1) cm(-2) and detection limit of -1.25 mM with a quick response time of -10.0 s. The presented studies showed that ZnO nanomaterials can be efficiently used as an antimicrobial agent and a highly sensitive non-enzymatic glucose sensor. PMID:24015509

  17. Biphasic toxicodynamic features of some antimicrobial agents on microbial growth: a dynamic mathematical model and its implications on hormesis

    PubMed Central

    2010-01-01

    Background In the present work, we describe a group of anomalous dose-response (DR) profiles and develop a dynamic model that is able to explain them. Responses were obtained from conventional assays of three antimicrobial agents (nisin, pediocin and phenol) against two microorganisms (Carnobacterium piscicola and Leuconostoc mesenteroides). Results Some of these anomalous profiles show biphasic trends which are usually attributed to hormetic responses. But they can also be explained as the result of the time-course of the response from a microbial population with a bimodal distribution of sensitivity to an effector, and there is evidence suggesting this last origin. In light of interest in the hormetic phenomenology and the possibility of confusing it with other phenomena, especially in the bioassay of complex materials we try to define some criteria which allow us to distinguish between sensu stricto hormesis and biphasic responses due to other causes. Finally, we discuss some problems concerning the metric of the dose in connection with the exposure time, and we make a cautionary suggestion about the use of bacteriocins as antimicrobial agents. Conclusions The mathematical model proposed, which combines the basis of DR theory with microbial growth kinetics, can generate and explain all types of anomalous experimental profiles. These profiles could also be described in a simpler way by means of bisigmoidal equations. Such equations could be successfully used in a microbiology and toxicology context to discriminate between hormesis and other biphasic phenomena. PMID:20723220

  18. Utility of Greater Wax Moth Larva (Galleria mellonella) for Evaluating the Toxicity and Efficacy of New Antimicrobial Agents.

    PubMed

    Desbois, Andrew P; Coote, Peter J

    2012-01-01

    There is an urgent need for new antimicrobial agents to combat infections caused by drug-resistant pathogens. Once a compound is shown to be effective in vitro, it is necessary to evaluate its efficacy in an animal infection model. Typically, this is achieved using a mammalian model, but such experiments are costly, time consuming, and require full ethical consideration. Hence, cheaper and ethically more acceptable invertebrate models of infection have been introduced, including the larvae of the greater wax moth Galleria mellonella. Invertebrates have an immune system that is functionally similar to the innate immune system of mammals, and often identical virulence and pathogenicity factors are used by human pathogenic microbes to infect wax moth larvae and mammals. Moreover, the virulence of many human pathogens is comparable in wax moth larvae and mammals. Using key examples from the literature, this chapter highlights the benefits of using the wax moth larva model to provide a rapid, inexpensive, and reliable evaluation of the toxicity and efficacy of new antimicrobial agents in vivo and prior to the use of more expensive mammalian models. This simple insect model can bridge the gap between in vitro studies and mammalian experimentation by screening out compounds with a low likelihood of success, while providing greater justification for further studies in mammalian systems. Thus, broader implementation of the wax moth larva model into anti-infective drug discovery and development programs could reduce the use of mammals during preclinical assessments and the overall cost of drug development. PMID:22305092

  19. In vitro culture system to determine MICs and MBCs of antimicrobial agents against Treponema pallidum subsp. pallidum (Nichols strain).

    PubMed Central

    Norris, S J; Edmondson, D G

    1988-01-01

    A new procedure for determining the susceptibility of Treponema pallidum subsp. pallidum to antimicrobial agents was developed, utilizing a tissue culture system which promotes the in vitro multiplication of this organism. In the absence of antibiotics, T. pallidum (Nichols virulent strain) multiplied an average of 10-fold when incubated for 7 days in the presence of Sf1Ep cottontail rabbit epithelial cell cultures. Varied concentrations of penicillin G, tetracycline, erythromycin, and spectinomycin were added to triplicate cultures to determine their effects on treponemal multiplication, motility, and virulence. The MIC of each antibiotic was defined as the lowest concentration which prevented treponemal multiplication, whereas the MBC was defined as the lowest concentration which abrogated the ability of the cultured treponemes to multiply and cause lesions in rabbits. The in vitro culture technique provided highly reproducible MICs and (in parentheses) MBCs of each of the antibiotics tested: aqueous penicillin G, 0.0005 (0.0025) microgram/ml; tetracycline, 0.2 (0.5) microgram/ml; erythromycin, 0.005 (0.005) microgram/ml; and spectinomycin, 0.5 (0.5) microgram/ml. The significance of these results in light of the in vivo activities and the previous in vitro evaluations of these antibiotics is discussed. The T. pallidum in vitro cultivation system shows promise as a method for studying the interaction between T. pallidum and antimicrobial agents and for screening new antibiotics for syphilis therapy. PMID:2964810

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

    PubMed Central

    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. PMID:26925267

  1. 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. PMID:26925267

  2. Chitin nanofibers as reinforcing and antimicrobial agents in carboxymethyl cellulose films: Influence of partial deacetylation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of edible, environmentally friendly, mechanically strong and antimicrobial biopolymer films for active food packaging has gained considerable interest in recent years. The present work deals with the extraction and deacetylation of chitin nanofibers (ChNFs) from crab shells and their...

  3. Isolation and characterization of two antimicrobial agents from mace (Myristica fragrans).

    PubMed

    Orabi, K Y; Mossa, J S; el-Feraly, F S

    1991-01-01

    The two antimicrobial resorcinols malabaricone B [1] and malabaricone C [2] were isolated from mace, the dried seed covers of Myristica fragrans. Both compounds exhibited strong antifungal and antibacterial activities. Structure modifications by methylation or reduction resulted in diminished activity. PMID:1955885

  4. 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.

  5. Synthesis, molecular modeling and structural characterization of vanillin derivatives as antimicrobial agents

    NASA Astrophysics Data System (ADS)

    Sun, Juan; Yin, Yong; Sheng, Gui-Hua; Yang, Zhi-Bo; Zhu, Hai-Liang

    2013-05-01

    Two vanillin derivatives have been designed and synthesized and their biological activities were also evaluated for antimicrobial activity. Their chemical structures are characterized by single crystal X-ray diffraction studies, 1H NMR, MS, and elemental analysis. Structural stabilization of them followed by intramolecular as well as intermolecular H-bonds makes these molecules as perfect examples in molecular recognition with self-complementary donor and acceptor units within a single molecule. Docking simulations have been performed to position compounds into the FtsZ active site to determine their probable binding model. Compound 3a shows the most potent biological activity, which may be a promising antimicrobial leading compound for the further research.

  6. Design, synthesis and biological evaluation of some new coumarin derivatives as potential antimicrobial agents.

    PubMed

    Singh, Lav Kumar; Priyanka; Singh, Vineeta; Katiyar, Diksha

    2015-01-01

    A series of 4-methyl-7-O-substituted coumarins (3-12) was synthesized and evaluated for in vitro antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), four Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris) and three fungal strains (Candida albicans, Cryptococcus terreus and Saccharomyces cerevisiae) by two-fold serial dilution technique. The results of bioactive assay showed that some of the synthesized coumarins displayed comparable or even better antibacterial and antifungal activities against tested strains in comparison with reference drugs erythromycin, novobiocin and amphotericin B. Compound 9 showed potent antimicrobial activities against seven of the nine microbial strains examined in this study with MIC values ranging between 1.09 and 25 µg/mL and was the most active compound of the series. The present work also describes the effect of substituent on bioactivity. PMID:25181986

  7. AFNOR validation of Premi Test, a microbiological-based screening tube-test for the detection of antimicrobial residues in animal muscle tissue.

    PubMed

    Gaudin, Valerie; Juhel-Gaugain, Murielle; Morétain, Jean-Pierre; Sanders, Pascal

    2008-12-01

    Premi Test contains viable spores of a strain of Bacillus stearothermophilus which is sensitive to antimicrobial residues, such as beta-lactams, tetracyclines, macrolides and sulphonamides. The growth of the strain is inhibited by the presence of antimicrobial residues in muscle tissue samples. Premi Test was validated according to AFNOR rules (French Association for Normalisation). The AFNOR validation was based on the comparison of reference methods (French Official method, i.e. four plate test (FPT) and the STAR protocol (five plate test)) with the alternative method (Premi Test). A preliminary study was conducted in an expert laboratory (Community Reference Laboratory, CRL) on both spiked and incurred samples (field samples). Several method performance criteria (sensitivity, specificity, relative accuracy) were estimated and are discussed, in addition to detection capabilities. Adequate agreement was found between the alternative method and the reference methods. However, Premi Test was more sensitive to beta-lactams and sulphonamides than the FPT. Subsequently, a collaborative study with 11 laboratories was organised by the CRL. Blank and spiked meat juice samples were sent to participants. The expert laboratory (CRL) statistically analysed the results. It was concluded that Premi Test could be used for the routine determination of antimicrobial residues in muscle of different animal origin with acceptable analytical performance. The detection capabilities of Premi Test for beta-lactams (amoxicillin, ceftiofur), one macrolide (tylosin) and tetracycline were at the level of the respective maximum residue limits (MRL) in muscle samples or even lower. PMID:19680855

  8. Composting of cow dung and crop residues using termite mounds as bulking agent.

    PubMed

    Karak, Tanmoy; Sonar, Indira; Paul, Ranjit K; Das, Sampa; Boruah, R K; Dutta, Amrit K; Das, Dilip K

    2014-10-01

    The present study reports the suitability of termite mounds as a bulking agent for composting with crop residues and cow dung in pit method. Use of 50 kg termite mound with the crop residues (stover of ground nut: 361.65 kg; soybean: 354.59 kg; potato: 357.67 kg and mustard: 373.19 kg) and cow dung (84.90 kg) formed a good quality compost within 70 days of composting having nitrogen, phosphorus and potassium as 20.19, 3.78 and 32.77 g kg(-1) respectively with a bulk density of 0.85 g cm(-3). Other physico-chemical and germination parameters of the compost were within Indian standard, which had been confirmed by the application of multivariate analysis of variance and multivariate contrast analysis. Principal component analysis was applied in order to gain insight into the characteristic variables. Four composting treatments formed two different groups when hierarchical cluster analysis was applied. PMID:25108475

  9. Occurrence of antimicrobial residues in Brazilian food animals in 2008 and 2009.

    PubMed

    Nonaka, C K V; Oliveira, A M G; Paiva, C R; Almeida, M P; Rezende, C P; Moraes, C G O; Botelho, B G; Souza, L F; Dias, P G

    2012-01-01

    Brazil is one of the most important countries as a producer and exporter of cattle and poultry. In 2009 cattle accounted for 30% of the export market and 41.4% for poultry meat. The Brazilian National Residues and Contaminants Control Plan (PNCRC) follows the guidelines set by the Codex Alimentarius Commission and checks compliance maximum residue limits (MRLs) to ensure the quality of these commodities. Kidney samples (n = 2978) were analysed between January 2008 and December 2009. Fifteen antibiotics of the macrolide and aminoglycoside groups (clindamycin, eritromycin, lincomycin, tylmicosin, tylosin, amikacin, apramycin, dihydrostreptomycin, gentamycin, higromycin, kanamycin, neomycin, spectinomycin, streptomycin, tobramycin) were determined by a microbiological screening method (FAST) and confirmed/quantified using liquid chromatography (LC-MS/MS and UPLC-MS/MS). In 2008, 1459 samples were analysed by a screening test and liquid chromatography with only one sample (0.07%) exceeded Brazilian legislation limits (>MRL). In 2009, 1519 samples were analysed and none exceeding Brazilian legislation limits (>MRL). The slaughterhouses of 16 states were monitored during the year of 2008, and 18 states were monitored in 2009, being the major producing states most sampled by the PNCRC. PMID:22129165

  10. Considering the antimicrobial sensitivity of the intestinal botulism agent Clostridium butyricum when treating concomitant infections.

    PubMed

    Fenicia, Lucia; Ferrini, Anna Maria; Anniballi, Fabrizio; Mannoni, Veruscka; Aureli, Paolo

    2003-01-01

    In Italy, neurotoxigenic Clostridium butyricum has been reported as a new agent of intestinal toxemia botulism, and most of the cases have been associated with enterocolitis. Although infections concomitant with botulism must be treated with antibiotics, this can increase the severity of botulism. We discuss the sensitivity of this agent to certain antibiotics, compared to findings on the sensitivity of C. botulinum. PMID:14758873

  11. Synthesis, Biological Evaluation and 2D-QSAR Study of Halophenyl Bis-Hydrazones as Antimicrobial and Antitubercular Agents

    PubMed Central

    Abdel-Aziz, Hatem A.; Eldehna, Wagdy M.; Fares, Mohamed; Al-Rashood, Sara T. A.; Al-Rashood, Khalid A.; Abdel-Aziz, Marwa M.; Soliman, Dalia H.

    2015-01-01

    In continuation of our endeavor towards the development of potent and effective antimicrobial agents, three series of halophenyl bis-hydrazones (14a–n, 16a–d, 17a and 17b) were synthesized and evaluated for their potential antibacterial, antifungal and antimycobacterial activities. These efforts led to the identification of five molecules 14c, 14g, 16b, 17a and 17b (MIC range from 0.12 to 7.81 μg/mL) with broad antimicrobial activity against Mycobacterium tuberculosis; Aspergillus fumigates; Gram positive bacteria, Staphylococcus aureus, Streptococcus pneumonia, and Bacillis subtilis; and Gram negative bacteria, Salmonella typhimurium, Klebsiella pneumonia, and Escherichia coli. Three of the most active compounds, 16b, 17a and 17b, were also devoid of apparent cytotoxicity to lung cancer cell line A549. Amphotericin B and ciprofloxacin were used as references for antifungal and antibacterial screening, while isoniazid and pyrazinamide were used as references for antimycobacterial activity. Furthermore, three Quantitative Structure Activity Relationship (QSAR) models were built to explore the structural requirements controlling the different activities of the prepared bis-hydrazones. PMID:25903147

  12. Evaluation of bishexadecyltrimethyl ammonium palladium tetrachloride based dual functional colloidal carrier as an antimicrobial and anticancer agent.

    PubMed

    Kaur, Gurpreet; Kumar, Sandeep; Dilbaghi, Neeraj; Kaur, Baljinder; Kant, Ravi; Guru, Santosh Kumar; Bhushan, Shashi; Jaglan, Sundeep

    2016-04-12

    We have developed a dual function carrier using bishexadecyltrimethyl ammonium palladium tetrachloride, which has anticancer as well as antibacterial activity, using a ligand insertion method with a simple and easy work procedure. The complex is prepared by a simple and cost effective method using hexadecyltrimethyl ammonium chloride and palladium chloride under controlled stoichiometry. Herein, we report the aggregation (self assembly) of the metallosurfactant having palladium as a counter ion, in aqueous medium along with its binding affinity with bovine serum albumin. The palladium surfactant has exhibited excellent antimicrobial efficacy against fungus and bacteria (both Gram-positive and Gram-negative bacteria). Cytotoxicity of palladium surfactant against cancerous (Human leukemia HL-60, pancreatic MIA-Pa-Ca-2 and prostate cancer PC-3) and healthy cells (fR2 human breast epithelial cells) was also evaluated using MTT assay. The present dual functional moiety shows a low IC50 value and has potential to be used as an anticancer agent. Our dual function carrier which itself possesses antimicrobial and anticancer activity represents a simple and effective system and can also be utilized as a drug carrier in the future. PMID:26961498

  13. 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. PMID:27216238

  14. 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

  15. Applications of chitosan powder with in situ synthesized nano ZnO particles as an antimicrobial agent.

    PubMed

    P, Mujeeb Rahman; Muraleedaran, K; Mujeeb, V M Abdul

    2015-01-01

    ZnO nanoparticles are immobilized on the chitosan matrix by an in situ sol-gel conversion of precursor molecules in a single step. Three different composites are prepared by varying the concentration of sodium hydroxide with same quantity of chitosan and zinc acetate dihydrate. The composites were characterized by FTIR, UV-visible spectra, and XRD. The observed decrease in the band width corresponding to OH and NH2 group in the composites is ascribed to the reduction of hydrogen bond due to the presence of ZnO nanoparticles. The direct evidence of the immobilization of nano ZnO particles in the matrix was identified by SEM. The average particle size values obtained for the nanoparticles, using Debye-Scherrer equation from XRD, is in the range 10-18nm. Optical studies proved that all the three composites studied have the same band gap energy (3.28eV) in agreement with the reported values. We observed that the composites possess excellent antimicrobial activity against Gram negative bacteria Escherichia coli (E. coli) and Gram positive bacteria Staphylococcus aureus (S. aureus) than chitosan. Based on the above studies, the biocompatible, eco-friendly and low-cost composite powder could be applied in various fields as an antimicrobial agent. PMID:25841382

  16. Reduced Susceptibility to Rifampicin and Resistance to Multiple Antimicrobial Agents among Brucella abortus Isolates from Cattle in Brazil

    PubMed Central

    Barbosa Pauletti, Rebeca; Reinato Stynen, Ana Paula; Pinto da Silva Mol, Juliana; Seles Dorneles, Elaine Maria; Alves, Telma Maria; de Sousa Moura Souto, Monalisa; Minharro, Silvia; Heinemann, Marcos Bryan; Lage, Andrey Pereira

    2015-01-01

    This study aimed to determine the susceptibility profile of Brazilian Brucella abortus isolates from cattle to eight antimicrobial agents that are recommended for the treatment of human brucellosis and to correlate the susceptibility patterns with origin, biotype and MLVA16-genotype of the strains. Screening of 147 B. abortus strains showed 100% sensitivity to doxycycline and ofloxacin, one (0.68%) strain resistant to ciprofloxacin, two strains (1.36%) resistant to streptomycin, two strains (1.36%) resistant to trimethoprim-sulfamethoxazole and five strains (3.40%) resistant to gentamicin. For rifampicin, three strains (2.04%) were resistant and 54 strains (36.73%) showed reduced sensitivity. Two strains were considered multidrug resistant. In conclusion, the majority of B. abortus strains isolated from cattle in Brazil were sensitive to the antimicrobials commonly used for the treatment of human brucellosis; however, a considerable proportion of strains showed reduced susceptibility to rifampicin and two strains were considered multidrug resistant. Moreover, there was no correlation among the drug susceptibility pattern, origin, biotype and MLVA16-genotypes of these strains. PMID:26181775

  17. Radiosensitivities of parabens and characterization of the radical species induced in this class of antimicrobial agents after gamma irradiation

    NASA Astrophysics Data System (ADS)

    Üstündaǧ, Ilknur; Korkmaz, Özden

    Radiosensitivities of methyl, ethyl, propyl and butyl parabens and sodium salts of methyl and propyl parabens (hereafter, MP, EP, PP, BP, SMP and SPP, respectively) were investigated by monitoring, through electron spin resonance (ESR) spectroscopy, the evolution under different experimental conditions of characteristic features of the radicalic species produced upon irradiation by gamma radiation. While ESR spectra of the studied parabens consisted of the sum of broad and narrow resonance lines of different microwave saturation and thermal characteristics, those of sodium salts appeared to consist of the sum of two overlapping narrow resonance lines. Radical species presented different room and high-temperature decay characteristics, depending on the extent of the cage effect created by the lattice networks on these species. A model based on the presence of two radical species presenting different spectroscopic and kinetic features described best the experimental data collected for parabens and their sodium salts. Radiation yields of the studied parabens towards gamma radiation were calculated to be low (G≤10-2), providing the opportunity of using these antimicrobial agents in food, cosmetics and drugs to be sterilized by radiation without much loss from their antimicrobial activities.

  18. Development of antimicrobial agents in the era of new and reemerging infectious diseases and increasing antibiotic resistance.

    PubMed

    Cassell, G H; Mekalanos, J

    2001-02-01

    During the past 2 decades, new infectious diseases have appeared and old ones previously thought to be controlled have reemerged. New and reemerging infectious agents will continue to pose serious threats well into the 21st century. The prediction that the threat of infectious disease may not diminish is supported by evidence that infectious agents cause many chronic diseases and cancer of previous unknown etiology. Moreover, the utility of existing antimicrobial agents is rapidly eroding, tipping the balance in favor of multidrug-resistant pathogens, and there appear to be few, if any, new classes of drugs currently in clinical development. The need for research directed toward development of new antibiotics has never been greater. Advances in research technologies and microbial genome sequencing in the past decade have led to identification of a large number of new targets. Functional genomics and integrative biology should validate these targets and provide the best opportunity for developing effective new therapies, improved diagnostic techniques, and better tools to understand host-pathogen interactions. PMID:11176866

  19. In Vitro Synergism between Azithromycin or Terbinafine and Topical Antimicrobial Agents against Pythium insidiosum.

    PubMed

    Itaqui, Sabrina R; Verdi, Camila M; Tondolo, Juliana S M; da Luz, Thaisa S; Alves, Sydney H; Santurio, Janio M; Loreto, Érico S

    2016-08-01

    We describe here in vitro activity for the combination of azithromycin or terbinafine and benzalkonium, cetrimide, cetylpyridinium, mupirocin, triclosan, or potassium permanganate. With the exception of potassium permanganate, the remaining antimicrobial drugs were active and had an MIC90 between 2 and 32 μg∕ml. The greatest synergism was observed for the combination of terbinafine and cetrimide (71.4%). In vivo experimental evaluations will clarify the potential of these drugs for the topical treatment of lesions caused by Pythium insidiosum. PMID:27216049

  20. Lipid composition and sensitivity of Prototheca wickerhamii to membrane-active antimicrobial agents.

    PubMed Central

    Sud, I J; Feingold, D S

    1979-01-01

    The lipid composition of Prototheca wickerhamii ATCC 16529 is presented and discussed in relation to the unique susceptibility of the organism to drugs of three membrane-active antimicrobial classes: the polyenes, the polymyxins, and the imidazoles. The presence of ergosterol in the neutral lipid fraction of the membrane is likely responsible for the exquisite susceptibility to amphotericin B. The presence of a large quantity of free fatty acids in the membrane appears responsible for imidazole susceptibility. The membrane determinants of polymyxin B susceptibility are less well defined. PMID:518077

  1. Nitric oxide nanoparticle technology: a novel antimicrobial agent in the context of current treatment of skin and soft tissue infection.

    PubMed

    Englander, Laura; Friedman, Adam

    2010-06-01

    Staphylococcus aureus infections account for the majority of skin and soft tissue infections in the United States. Staphylococcus aureus is rapidly evolving resistance to contemporary topical as well as systemic antibiotics. Alternatives to current treatment options for skin and soft tissue infections are needed for more effective treatment now and in the future. Nitric oxide's proven roles in both wound repair and as an antimicrobial agent make it an excellent candidate for the treatment of skin infections. Recent attempts at novel nitric oxide therapies, in the form of nitric oxide donors, have shown limited potential in treating cutaneous infection. However, more recent developments in nitric oxide delivery, using nitric oxide nanoparticle technology, demonstrate substantial promise in the promotion of wound repair and eradication of skin and soft tissue infections. PMID:20725551

  2. 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. PMID:26687131

  3. Apple Puree-Alginate Edible Coating as Carrier of Antimicrobial Agents to Prolong Shelf-Life of Fresh-Cut Apples

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Stenusine, an antimicrobial agent in the rove beetle genus Stenus (Coleoptera, Staphylinidae).

    PubMed

    Lusebrink, Inka; Dettner, Konrad; Seifert, Karlheinz

    2008-08-01

    Stenusine is well known as the alkaloid, discharged by the rove beetle, genus Stenus Latreille (Coleoptera, Staphylinidae). The Stenus beetles employ the alkaloid as an escape mechanism when on water surfaces. In the case of danger, they lower their abdomen and emit stenusine from their pygidial glands. Stenusine shows a low surface tension and therefore a high spreading pressure; these properties propel the beetle quickly over the water. Many Steninae do not live in habitats with open waters, but in detritus, leaf litter, mosses, etc. This raises the possibility that stenusine might also have another function, e.g., as antibiotic or fungicide. Stenus beetles show an intense grooming behaviour. With gas chromatography-mass spectrometry analyses we could prove that they cover themselves with their secretion. To tests its antimicrobial properties we conducted agar diffusion tests with stenusine and norstenusine, another substance that is abundant in most Stenus species. Both compounds have an antimicrobial effect on entomopathogenic bacteria and fungi. Stenusine not only allows for an extraordinary method of locomotion on water surfaces, it also protects the Steninae from being infested with microorganisms. PMID:18392795

  5. Biodegradable gelatin-chitosan films incorporated with essential oils as antimicrobial agents for fish preservation.

    PubMed

    Gómez-Estaca, J; López de Lacey, A; López-Caballero, M E; Gómez-Guillén, M C; Montero, P

    2010-10-01

    Essential oils of clove (Syzygium aromaticum L.), fennel (Foeniculum vulgare Miller), cypress (Cupressus sempervirens L.), lavender (Lavandula angustifolia), thyme (Thymus vulgaris L.), herb-of-the-cross (Verbena officinalis L.), pine (Pinus sylvestris) and rosemary (Rosmarinus officinalis) were tested for their antimicrobial activity on 18 genera of bacteria, which included some important food pathogen and spoilage bacteria. Clove essential oil showed the highest inhibitory effect, followed by rosemary and lavender. In an attempt to evaluate the usefulness of these essential oils as food preservatives, they were also tested on an extract made of fish, where clove and thyme essential oils were the most effective. Then, gelatin-chitosan-based edible films incorporated with clove essential oil were elaborated and their antimicrobial activity tested against six selected microorganisms: Pseudomonas fluorescens, Shewanella putrefaciens, Photobacterium phosphoreum, Listeria innocua, Escherichia coli and Lactobacillus acidophilus. The clove-containing films inhibited all these microorganisms irrespectively of the film matrix or type of microorganism. In a further experiment, when the complex gelatin-chitosan film incorporating clove essential oil was applied to fish during chilled storage, the growth of microorganisms was drastically reduced in gram-negative bacteria, especially enterobacteria, while lactic acid bacteria remained practically constant for much of the storage period. The effect on the microorganisms during this period was in accordance with biochemical indexes of quality, indicating the viability of these films for fish preservation. PMID:20688230

  6. Stenusine, an antimicrobial agent in the rove beetle genus Stenus (Coleoptera, Staphylinidae)

    NASA Astrophysics Data System (ADS)

    Lusebrink, Inka; Dettner, Konrad; Seifert, Karlheinz

    2008-08-01

    Stenusine is well known as the alkaloid, discharged by the rove beetle, genus Stenus Latreille (Coleoptera, Staphylinidae). The Stenus beetles employ the alkaloid as an escape mechanism when on water surfaces. In the case of danger, they lower their abdomen and emit stenusine from their pygidial glands. Stenusine shows a low surface tension and therefore a high spreading pressure; these properties propel the beetle quickly over the water. Many Steninae do not live in habitats with open waters, but in detritus, leaf litter, mosses, etc. This raises the possibility that stenusine might also have another function, e.g., as antibiotic or fungicide. Stenus beetles show an intense grooming behaviour. With gas chromatography mass spectrometry analyses we could prove that they cover themselves with their secretion. To tests its antimicrobial properties we conducted agar diffusion tests with stenusine and norstenusine, another substance that is abundant in most Stenus species. Both compounds have an antimicrobial effect on entomopathogenic bacteria and fungi. Stenusine not only allows for an extraordinary method of locomotion on water surfaces, it also protects the Steninae from being infested with microorganisms.

  7. C31G, a new agent for oral use with potent antimicrobial and antiadherence properties.

    PubMed Central

    Corner, A M; Dolan, M M; Yankell, S L; Malamud, D

    1988-01-01

    C31G, an equimolar mixture of alkyl dimethyl glycine and alkyl dimethyl amine oxide, was evaluated for antimicrobial and antiadherence properties. The efficacy of C31G, its two components, and several commercial mouth rinses was determined in assays measuring inhibition of glycolysis, inhibition of bacterial adherence, and MICs. Inhibition of glycolysis was determined by using a saliva sediment model, with glycolytic activity expressed as the change in pH relative to that of a control. Adherence studies were undertaken with Streptococcus sobrinus 6715 to measure inhibition of adherence to nichrome wires. MICs were determined against selected microorganisms by standard methods. C31G demonstrated broad-spectrum antimicrobial properties, with activity against both gram-positive and gram-negative organisms and Candida albicans, a yeast. C31G inhibited both glycolysis by salivary bacteria and adherence of Streptococcus strains to wire mesh. C31G was more effective in the assays conducted than any commercial formulation tested and was as effective as chlorhexidine. A synergistic effect was demonstrated between the individual components of C31G, and no loss of activity was noted when it was formulated into a mouth rinse vehicle. PMID:3364952

  8. Essential oils and herbal extracts as antimicrobial agents in cosmetic emulsion.

    PubMed

    Herman, Anna; Herman, Andrzej Przemysław; Domagalska, Beata Wanda; Młynarczyk, Andrzej

    2013-06-01

    The cosmetic industry adapts to the needs of consumers seeking to limit the use of preservatives and develop of preservative-free or self-preserving cosmetics, where preservatives are replaced by raw materials of plant origin. The aim of study was a comparison of the antimicrobial activity of extracts (Matricaria chamomilla, Aloe vera, Calendula officinalis) and essential oils (Lavandulla officinallis, Melaleuca alternifolia, Cinnamomum zeylanicum) with methylparaben. Extracts (2.5 %), essential oils (2.5 %) and methylparaben (0.4 %) were tested against Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, Candida albicans ATCC 14053. Essentials oils showed higher inhibitory activity against tested microorganism strain than extracts and methylparaben. Depending on tested microorganism strain, all tested extracts and essential oils show antimicrobial activity 0.8-1.7 and 1-3.5 times stronger than methylparaben, respectively. This shows that tested extracts and essential oils could replace use of methylparaben, at the same time giving a guarantee of microbiological purity of the cosmetic under its use and storage. PMID:24426114

  9. Synthesis and Evaluation of Selected Benzimidazole Derivatives as Potential Antimicrobial Agents.

    PubMed

    Alasmary, Fatmah A S; Snelling, Anna M; Zain, Mohammed E; Alafeefy, Ahmed M; Awaad, Amani S; Karodia, Nazira

    2015-01-01

    A library of 53 benzimidazole derivatives, with substituents at positions 1, 2 and 5, were synthesized and screened against a series of reference strains of bacteria and fungi of medical relevance. The SAR analyses of the most promising results showed that the antimicrobial activity of the compounds depended on the substituents attached to the bicyclic heterocycle. In particular, some compounds displayed antibacterial activity against two methicillin-resistant Staphylococcus aureus (MRSA) strains with minimum inhibitory concentrations (MICs) comparable to the widely-used drug ciprofloxacin. The compounds have some common features; three possess 5-halo substituents; two are derivatives of (S)-2-ethanaminebenzimidazole; and the others are derivatives of one 2-(chloromethyl)-1H-benzo[d]imidazole and (1H-benzo[d]imidazol-2-yl)methanethiol. The results from the antifungal screening were also very interesting: 23 compounds exhibited potent fungicidal activity against the selected fungal strains. They displayed equivalent or greater potency in their MIC values than amphotericin B. The 5-halobenzimidazole derivatives could be considered promising broad-spectrum antimicrobial candidates that deserve further study for potential therapeutic applications. PMID:26307956

  10. A fermentation assay to evaluate the effectiveness of antimicrobial agents on gut microflora.

    PubMed

    Shanmugavelu, S; Ruzickova, G; Zrustova, J; Brooker, J D

    2006-10-01

    The measurement of gas produced as a fermentation end product in vitro was correlated with absorbance as a measure of bacterial growth and was used as a rapid screening procedure to test the antimicrobial activity of certain essential oil and tannin secondary plant metabolites on gastrointestinal microorganisms from chickens. The assay was optimised using Clostridium perfringens and Lactobacillus fermentum, and tested in antimicrobial assays against C. perfringens; the minimum inhibitory concentration for each essential oil and condensed tannin was determined. The effect of penicillin-G on C. perfringens, in both growth and fermentation assays, was similar, and for all secondary metabolites tested, concentrations that inhibited fermentation were also bacteriocidal. The assay was also used to demonstrate the effect of dietary composition and enzyme supplementation on fermentation of mixed gut microflora in vitro; results are compared with in vivo results for the same dietary treatments. The data demonstrate that the effects of bioactive secondary plant products and feed composition on individual organisms or mixed gut microflora can be tested by analysis of fermentative activity in vitro, and that this provides a rapid assay for testing potential poultry feed additives before in vivo trials. PMID:16632004

  11. Development of new 5-(chromene-3-yl)methylene-2,4-thiazolidinediones as antimicrobial agents

    PubMed Central

    NASTASĂ, CRISTINA MARIANA; DUMA, MIHAELA; PÎRNĂU, ADRIAN; VLASE, LAURIAN; TIPERCIUC, BRÎNDUŞA; ONIGA, OVIDIU

    2016-01-01

    Background and aims In the context of the increasing phenomenon of microbial resistance to usual drugs, the development of new treatment strategies and new therapeutic protocols is a constant need. Thiazolidinedione and chromone represent two important scaffolds in medicinal chemistry due to their large pharmacological applicability. Methods We synthesized a new 5-(chromene-3-yl)methylene-2,4-thiazolidinedione starting from 6,8-dichloro-4-oxo-4H-chromene-3-carbaldehyde. Then, by treating with different α-bromoalkylarylketones, we obtained N-substituted derivatives. All new compounds were investigated for their antimicrobial potential, using the diffusion method, against Listeria monocytogenes ATCC 13932, Staphylococcus aureus ATCC 49444, Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028 and Candida albicans ATCC 10231. Three concentrations, 10 mg/ml, 5 mg/ml and 1 mg/ml of compounds were used. The results were evaluated by the measurement of the inhibition zone diameters and compared to those of gentamicin and fluconazole respectively, as reference drugs. Results All new synthesized compounds were characterized using physico-chemical and spectrometric methods. They displayed modest to good antimicrobial activity. New molecules 8, 9 and 10 may represent promising candidates, showing zone inhibition diameters superior to those of reference drugs. Conclusions This work presents chemical synthesis, characterization and investigation of the antibacterial and antifungal potential of 5-(chromene-3-yl)methylene-2,4-thiazolidinedione derivatives, which may be worthy of future research for designing new chemical entities. PMID:27004035

  12. Efflux pump activity in fluoroquinolone and tetracycline resistant Salmonella and E. coli implicated in reduced susceptibility to household antimicrobial cleaning agents.

    PubMed

    Thorrold, C A; Letsoalo, M E; Dusé, A G; Marais, E

    2007-02-15

    It has been shown that the inappropriate use of antimicrobial household agents selects for organisms with resistance mechanisms (e.g. efflux pumps), which could lead to the development of antibiotic resistance. The reverse hypothesis, that antibiotic-resistant organisms become tolerant to other antibacterial agents (e.g. disinfectants) due to the action of efflux pumps, has however not been extensively examined. The objective of this study was to establish whether there is a link between antibiotic resistance in potential gastrointestinal pathogens and reduced sensitivity of these organisms to commonly used household antimicrobial agents. In this study, tetracycline and ofloxacin sensitive and resistant Escherichia coli (9 strains) and Salmonella spp. (8 strains) were isolated from poultry and clinical samples. In order to assess whether these bacteria had active efflux pumps, ethidium bromide accumulation assays were performed. Extrusion of the active components of three commercial household agents (triclosan, sodium salicylate, and ortho-phenylphenol) by efflux pumps was tested using spectrophotometric accumulation assays. In order to simulate the kitchen environment, in-use disinfectant testing using the commercial household agents was performed to determine changes in their efficacy due to antibiotic resistance. Active efflux pump activity and extrusion of all three active ingredients was observed only in the antibiotic resistant organisms. The antibiotic sensitive bacteria were also more susceptible than the resistant isolates to the household antimicrobial agents at concentrations below that recommended by the manufacturer. These resistant bacteria could potentially be selected for and result in hard to treat infections. PMID:17126442

  13. Comparison of risk-based versus random sampling in the monitoring of antimicrobial residues in Danish finishing pigs.

    PubMed

    Alban, Lis; Rugbjerg, Helene; Petersen, Jesper Valentin; Nielsen, Liza Rosenbaum

    2016-06-01

    In Denmark, a monitoring program for residues of antimicrobials in pork is in place involving annual testing of around 20,000 samples from finishing pigs corresponding to 0.1% of the animals slaughtered. Annually, zero to two samples are found above the maximum residue limit. Both authorities and industry have expressed interest in adjusting the monitoring to a risk-based system. The objective of this study was to assess the opportunities and consequences of the monitoring considering: 1) replacing the current bioassay with high-performance liquid chromatography-mass spectrometry (HPLC LC-MS/MS), 2) replacing kidney with muscles as sample matrix, and 3) using indicators to identify high-risk (HR) herds and increase sampling intensity in these herds, lowering sampling in the low-risk (LR) herds, while aiming at continued detection of similar numbers of test-positives at the lowest possible costs. A state-of-the-art stochastic scenario tree modelling approach including economic evaluation of different model outcomes was used. A total of six scenarios were run for penicillin and tetracycline, respectively. Relevant information was obtained through the literature, statistical analysis of existing data as well as consultations with laboratory and slaughterhouse experts. Abattoir recordings of chronic pleuritis were used as an indicator for finishing pig herds (HR=within-herd prevalence>40%). Such risk-based monitoring would have to use muscles and not kidneys, because of logistic challenges in identifying and storing of plucks until testing. However, the bioassay cannot be used on muscle tissue due to low sensitivity for tetracyclines. Different plausible combinations of sample sizes were also modelled. The HPLC LC-MS/MS method detected the same number of cases compared to the bioassay when kidney was used as matrix. HPLC LC-MS/MS has a higher sensitivity when used on muscle but it is almost twice as costly as the bioassay. Risk-based sampling resulted in detection of

  14. Spectrum of antimicrobial activity and user acceptability of the hand disinfectant agent Sterillium Gel.

    PubMed

    Kampf, G; Rudolf, M; Labadie, J-C; Barrett, S P

    2002-10-01

    The antimicrobial efficacy of alcohol-based hand gels has been shown to be significantly less than liquid hand rubs probably because of a lower concentration of alcohol. Sterillium Gel is the first hand gel with 85% ethanol. Its antimicrobial efficacy and user acceptability was studied. Bactericidal activity was tested according to prEN 12054 against Staphylococcus aureus, Enterococcus hirae, Pseudomonas aeruginosa and Escherichia coli (suspension test) and EN 1500 (15 volunteers; four replicates), fungicidal activity according to EN 1275 against Candida albicans and spores of Aspergillus niger (suspension test) and tuberculocidal activity against Mycobacterium terrae using the DGHM suspension test. Virucidal activity was determined in suspension tests based on reduction of infectivity with and without interfering substances (10% fetal calf serum; 0.3% erythrocytes and 0.3% bovine serum albumin). Ninety-six healthcare workers in hospitals in France and the UK used the gel for four weeks and assessed it by filling out a questionnaire. The gel was bactericidal (a reduction factor of > 10(5)-fold), tuberculocidal (reduction factor > 10(5)) and fungicidal (reduction factor > 10(4)) in 30 s. Irrespective of interfering substances the gel inactivated orthopoxvirus and herpes simplex virus type 1 and 2 in 15 s, adenovirus in 2 min, poliovirus in 3 min and papovavirus in 15 min by a factor of > 10(4)-fold. Rotavirus and human immunodeficiency virus were inactivated in 30 s (without interfering substances). Under practical use conditions it was as effective in 30 s as the reference alcohol in 60 s. Most users described the tackiness, aggregation, skin feeling after use and smell as positive or acceptable. A total of 65.6% assessed the new gel to be better than a comparator irrespective of its type (gel or liquid). Overall Sterillium Gel had a unique spectrum of antimicrobial activity. It is probably the first alcohol-based hand gel to pass EN 1500 in 30 s. Due to the

  15. Potential of the essential oil from Pimenta pseudocaryophyllus as an antimicrobial agent.

    PubMed

    Suzuki, Érika Yoko; Baptista, Edilene Bolutari; Resende Do Carmo, Antônio Márcio; Miranda Chaves, Maria Das Graças Afonso; Chicourel, Elizabeth Lemos; Barbosa Raposo, Nádia Rezende

    2014-09-01

    This study evaluated the effectiveness of the essential oil of Pimenta pseudocaryophyllus in inhibiting the growth of the main bacteria responsible for bad perspiration odor (Staphylococcus epidermidis, Proteus hauseri, Micrococcus yunnanensis and Corynebacterium xerosis). The chemical profile of the essential oil was evaluated by high-resolution gas chromatography (HR-GC) and four constituents were identified, eugenol being the major component (88.6%). The antimicrobial activity was evaluated by means of the turbidimetric method, using the microdilution assay. The minimum inhibitory concentration (MIC) values of the essential oil ranged from 500 to 1,000 μg mL⁻¹. Scanning electron microscope (SEM) observations confirmed the physical damage and morphological alteration of the test bacteria treated with the essential oil, reference drugs and eugenol. The findings of the study demonstrated that this essential oil can be used in the formulation of personal care products. PMID:25296683

  16. Sarothrin from Alkanna orientalis is an antimicrobial agent and efflux pump inhibitor

    PubMed Central

    Bame, Jessica R.; Graf, Tyler N.; Junio, Hiyas A.; Bussey, R. Owen; Jarmusch, Scott A.; El-Elimat, Tamam; Falkinham, Joseph O.; Oberlies, Nicholas H.; Cech, Richard A.; Cech, Nadja B.

    2015-01-01

    An Alkanna orientalis leaf and flower extract inhibited the growth of Staphylococcus aureus, a pathogen that causes an estimated 478,000 hospitalizations in the US annually. Bioassay-guided fractionation of A. orientalis resulted in isolation of the flavonoid sarothrin (5,7,4′-trihydroxy-3,6,8-trimethoxyflavone), which inhibited the growth of Mycobacterium smegmatis (MIC 75 μM) and S. aureus (MIC >800 μM), and possessed efflux pump inhibitory activity. This is the first report of antimicrobial or efflux pump inhibitory activity of sarothrin, and of its presence in A. orientalis. Our findings suggest that the effectiveness of A. orientalis extracts is due to a combination of multiple constituents, including sarothrin. PMID:23468310

  17. Impact of medicated feed along with clay mineral supplementation on Escherichia coli resistance to antimicrobial agents in pigs after weaning in field conditions.

    PubMed

    Jahanbakhsh, Seyedehameneh; Kabore, Kiswendsida Paul; Fravalo, Philippe; Letellier, Ann; Fairbrother, John Morris

    2015-10-01

    The aim of this study was to examine changes in antimicrobial resistance (AMR) phenotype and virulence and AMR gene profiles in Escherichia coli from pigs receiving in-feed antimicrobial medication following weaning and the effect of feed supplementation with a clay mineral, clinoptilolite, on this dynamic. Eighty E. coli strains isolated from fecal samples of pigs receiving a diet containing chlortetracycline and penicillin, with or without 2% clinoptilolite, were examined for antimicrobial resistance to 15 antimicrobial agents. Overall, an increased resistance to 10 antimicrobials was observed with time. Supplementation with clinoptilolite was associated with an early increase but later decrease in blaCMY-2, in isolates, as shown by DNA probe. Concurrently, a later increase in the frequency of blaCMY-2 and the virulence genes iucD and tsh was observed in the control pig isolates, being significantly greater than in the supplemented pigs at day 28. Our results suggest that, in the long term, supplementation with clinoptilolite could decrease the prevalence of E. coli carrying certain antimicrobial resistance and virulence genes. PMID:26412523

  18. Quaternary ammonium biocides as antimicrobial agents protecting historical wood and brick.

    PubMed

    Rajkowska, Katarzyna; Koziróg, Anna; Otlewska, Anna; Piotrowska, Małgorzata; Nowicka-Krawczyk, Paulina; Brycki, Bogumił; Kunicka-Styczyńska, Alina; Gutarowska, Beata

    2016-01-01

    Quaternary ammonium compounds (QACs) are widely used in disinfection of water, surfaces and instruments as well as in textile, leather and food industries because of their relatively low toxicity, broad antimicrobial spectrum, non-volatility and chemical stability. Due to these advantages, QACs are also used in restoration and can be applied on historical material. The aim of this study was to determine the usefulness of biocides based on quaternary ammonium salts and containing various excipients in the protection of historical materials against microbial growth. The study determined the antimicrobial activity of three biocides against bacteria: Pseudomonas fluorescens, Staphylococcus equorum, Bacillus cereus, Bacillus muralis, Sporosarcina aquimarina and Rhodococcus fascians, and moulds: Chaetomium globosum, Penicillium citreonigrum, Cladosporium cladosporioides I, Acremonium strictum, Aspergillus fumigatus and Cladosporium cladosporioides II, all isolated from historical wood and brick. Staphylococcus equorum, Bacillus cereus, Sporosarcina aquimarina and Rhodococcus fascians bacteria, and Cladosporium cladosporioides I and Acremonium strictum moulds showed high sensitivity to quaternary ammonium biocides. Historical wood can be effectively disinfected by three applications of biocide A (30% v/v) containing dodecyl dimethyl ammonium chloride (DDAC), citric acid, propiconazole and propanol. Disinfection of historical brick can be carried out by three applications of 6% v/v solutions of biocide B (based on DDAC and ethylenediaminetetraacetic acid - EDTA) or biocide C (containing a non-ionic surfactant, DDAC and EDTA). Effective protection of historical building materials against microbial growth for a period of seven days can be achieved by the application of biocide A (30% v/v) on the wood surface and biocide B (6% v/v) on the brick surface. PMID:26629794

  19. Effect of Different Obturation Materials on Residual Antimicrobial Activity of 2% Chlorhexidine in Dentin at Different Time Intervals: An Ex Vivo Study

    PubMed Central

    Bolhari, Behnam; Dehghan, Somayyeh; Sharifian, Mohammad Reza; Bahador, Abbas

    2015-01-01

    Objectives: The aim of this study was to evaluate the effect of gutta percha/AH26 and Resilon/RealSeal SE on residual antimicrobial activity of chlorhexidine (CHX) in human root dentin and suggest the best filling material when CHX is used as final irrigant. Materials and Methods: One-hundred and forty-four single-rooted human teeth were selected for this study. Canals were instrumented to the apical size #35. Smear layer was removed using 5.25% NaOCl and 17% EDTA and then 108 teeth were irrigated with 2% CHX and randomly divided into three groups of gutta percha/AH26, Resilon/RealSeal SE and positive controls. Each group was divided into three subgroups for different time intervals (one, three and six weeks). Thirty-six teeth, as negative controls, were irrigated with saline and obturated with gutta percha/AH26 and Resilon/RealSeal SE. Dentin powder was prepared at the afore-mentioned intervals. After exposure to Enterococcus faecalis for 24 hours, colony forming units (CFUs) were counted and residual antimicrobial activity was calculated. The data were analyzed using the Kruskal Wallis test and one-way ANOVA. The significance level was set at P<0.05. Results: The antimicrobial activity of CHX gradually decreased in a time-dependent manner but it maintained over 95% of its antimicrobial activity after six weeks. Moreover, Resilon/RealSeal SE significantly decreased the antimicrobial activity of CHX in comparison with gutta-percha/AH26 (P<0.05). Conclusion: After a final irrigation with CHX, gutta-percha/AH26 is a better choice for root canal obturation. PMID:27252755

  20. Efficacy of antimicrobial property of two commercially available chemomechanical caries removal agents (Carisolv and Papacarie): An ex vivo study

    PubMed Central

    Reddy, Maram Vinay Chand; Shankar, A.J. Sai; Pentakota, Venkata Girish; Kolli, Harika; Ganta, Haritha; Katari, Pavan Kumar

    2015-01-01

    Purpose: The purpose of the study is to evaluate the antimicrobial efficacy of Carisolv and Papacarie. There are only a few studies comparing the primary teeth. The objective of this study is to assess the effects of Carisolv and Papacarie on cariogenic flora and to compare them. Materials and Methods: Fifteen children aged 4–8 years who had at least two primary molars with broad occlusal cavitated lesions showing brown and softened dentin samples were selected. The selected 30 teeth were randomly divided into two groups of 15 teeth each for Carisolv and Papacarie. Dentin samples of both groups were taken prior to and following caries removal. The total viable count and lactobacilli count were determined and expressed as colony forming units per milliliter. The two methods of caries removal were then compared and the data were statistically analyzed. Results: The data of both agents (groups) were analyzed by Wilcoxon signed-rank test before and after application and showed statistical significance. Inter-comparison of data of both groups was analyzed by Mann–Whitney U test for total viable count and total Lactobacillus count which showed no statistical significance. Conclusion: Carisolv and Papacarie have similar antibacterial efficacy against cariogenic flora as chemomechanical caries removal agents. PMID:26236677

  1. 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.

  2. Chemo-sensitization of fungal pathogens to antimicrobial agents using benzaldehyde analogs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Activity of conventional antifungal agents, fludioxonil, strobilurin and antimycinA, which target the oxidative and osmotic stress response systems, was elevated by co-application of certain analogs of benzaldehyde. Fungal tolerance to 2,3-dihydroxybenzaldehyde or 2,3-dihydroxybenzoic acid was foun...

  3. Oregano essential oil-pectin edible films as anti-quorum sensing and food antimicrobial agents

    PubMed Central

    Alvarez, Maria V.; Ortega-Ramirez, Luis A.; Gutierrez-Pacheco, M. Melissa; Bernal-Mercado, A. Thalia; Rodriguez-Garcia, Isela; Gonzalez-Aguilar, Gustavo A.; Ponce, Alejandra; Moreira, Maria del R.; Roura, Sara I.; Ayala-Zavala, J. Fernando

    2014-01-01

    Edible films can be used as carriers for antimicrobial compounds to assure food safety and quality; in addition, pathogenesis of food bacteria is related to a cell to cell communication mechanism called quorum sensing (QS). Oregano essential oil (OEO) has proved to be useful as food antimicrobial; however, its food applications can be compromised by the volatile character of its active constituents. Therefore, formulation of edible films containing OEO can be an alternative to improve its food usages. QS inhibitory activity of OEO and pectin-OEO films was evaluated using Chromobacterium violaceum as bacterial model. Additionally, antibacterial activity was tested against Escherichia coli O157:H7, Salmonella Choleraesuis, Staphylococcus aureus, and Listeria monocytogenes. OEO was effective to inhibit bacterial growth at MIC of 0.24 mg/mL for all tested bacteria and MBC of 0.24, 0.24, 0.48, and 0.24 mg/mL against E. coli O157:H7, S. Choleraesuis, S. aureus, and L. monocytogenes, respectively. Pectin-films incorporated with 36.1 and 25.9 mg/mL of OEO showed inhibition diameters of 16.3 and 15.2 mm for E. coli O157:H7; 18.1 and 24.2 mm for S. Choleraesuis; 20.8 and 20.3 mm for S. aureus; 21.3 and 19.3 mm for L. monocytogenes, respectively. Pectin-OEO film (15.7 mg/mL) was effective against E. coli O157:H7 (9.3 mm), S. aureus (9.7 mm), and L. monocytogenes (9.2 mm), but not for S. Choleraesuis. All concentrations of OEO (0.0156, 0.0312, 0.0625 and 0.125 mg/mL) and pectin-OEO films (15.7, 25.9 and 36.1 mg/mL) showed a significant anti-QS activity expressed as inhibition of violacein production by C. violaceum. Additionally, the application of pectin-OEO films was effective reducing total coliforms, yeast, and molds of shrimp and cucumber slices stored at 4°C during 15 d. These results demonstrated the potential of pectin films enriched with OEO as food related microorganisms and QS inhibitors. PMID:25566215

  4. Development of flexible antimicrobial films using essential oils as active agents.

    PubMed

    López, P; Sánchez, C; Batlle, R; Nerín, C

    2007-10-17

    The antimicrobial activity in the vapor-phase of laboratory-made flexible films of polypropylene (PP) and polyethylene/ethylene vinyl alcohol copolymer (PE/EVOH) incorporating essential oil of cinnamon ( Cinnamomum zeylanicum), oregano ( Origanum vulgare), clove ( Syzygium aromaticum), or cinnamon fortified with cinnamaldehyde was evaluated against a wide range of microorganisms: the Gram-negative bacteria Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruginosa, and Salmonella choleraesuis; the Gram-positive bacteria Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Enterococcus faecalis; the molds Penicillium islandicum, Penicillium roqueforti, Penicillium nalgiovense, Eurotium repens, and A spergillus flavus and the yeasts Candida albicans, Debaryomyces hansenii, and Zigosaccharomyces rouxii. Films with a nominal concentration of 4% (w/w) of fortified cinnamon or oregano essential oil completely inhibited the growth of the fungi; higher concentrations were required to inhibit the Gram-positive bacteria (8 and 10%, respectively), and higher concentrations still were necessary to inhibit the Gram-negative bacteria. PP films were more effective than PE/EVOH films. The atmospheres generated by the antimicrobial films inside Petri dishes were quantitatively analyzed using headspace-single drop microextraction (HS-SDME) in combination with gas chromatography-mass spectrometry (GC-MS). The analyses showed that the oregano-fortified PP films released higher levels of carvacrol and thymol, and the cinnamon-fortified PP films released higher levels of cinnamaldehyde, during the first 3-6 h of incubation, than the corresponding PE/EVOH films. Shelf-life tests were also performed, demonstrating that the antifungal activities of the films persisted for more than two months after their manufacture. In addition, migration tests (overall and specific) were performed, using both aqueous and fatty simulants, to ensure that the films meet EU regulations

  5. Oregano essential oil-pectin edible films as anti-quorum sensing and food antimicrobial agents.

    PubMed

    Alvarez, Maria V; Ortega-Ramirez, Luis A; Gutierrez-Pacheco, M Melissa; Bernal-Mercado, A Thalia; Rodriguez-Garcia, Isela; Gonzalez-Aguilar, Gustavo A; Ponce, Alejandra; Moreira, Maria Del R; Roura, Sara I; Ayala-Zavala, J Fernando

    2014-01-01

    Edible films can be used as carriers for antimicrobial compounds to assure food safety and quality; in addition, pathogenesis of food bacteria is related to a cell to cell communication mechanism called quorum sensing (QS). Oregano essential oil (OEO) has proved to be useful as food antimicrobial; however, its food applications can be compromised by the volatile character of its active constituents. Therefore, formulation of edible films containing OEO can be an alternative to improve its food usages. QS inhibitory activity of OEO and pectin-OEO films was evaluated using Chromobacterium violaceum as bacterial model. Additionally, antibacterial activity was tested against Escherichia coli O157:H7, Salmonella Choleraesuis, Staphylococcus aureus, and Listeria monocytogenes. OEO was effective to inhibit bacterial growth at MIC of 0.24 mg/mL for all tested bacteria and MBC of 0.24, 0.24, 0.48, and 0.24 mg/mL against E. coli O157:H7, S. Choleraesuis, S. aureus, and L. monocytogenes, respectively. Pectin-films incorporated with 36.1 and 25.9 mg/mL of OEO showed inhibition diameters of 16.3 and 15.2 mm for E. coli O157:H7; 18.1 and 24.2 mm for S. Choleraesuis; 20.8 and 20.3 mm for S. aureus; 21.3 and 19.3 mm for L. monocytogenes, respectively. Pectin-OEO film (15.7 mg/mL) was effective against E. coli O157:H7 (9.3 mm), S. aureus (9.7 mm), and L. monocytogenes (9.2 mm), but not for S. Choleraesuis. All concentrations of OEO (0.0156, 0.0312, 0.0625 and 0.125 mg/mL) and pectin-OEO films (15.7, 25.9 and 36.1 mg/mL) showed a significant anti-QS activity expressed as inhibition of violacein production by C. violaceum. Additionally, the application of pectin-OEO films was effective reducing total coliforms, yeast, and molds of shrimp and cucumber slices stored at 4°C during 15 d. These results demonstrated the potential of pectin films enriched with OEO as food related microorganisms and QS inhibitors. PMID:25566215

  6. 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

  7. Secondary Metabolites from Plants Inhibiting ABC Transporters and Reversing Resistance of Cancer Cells and Microbes to Cytotoxic and Antimicrobial Agents

    PubMed Central

    Wink, Michael; Ashour, Mohamed L.; El-Readi, Mahmoud Zaki

    2012-01-01

    Fungal, bacterial, and cancer cells can develop resistance against antifungal, antibacterial, or anticancer agents. Mechanisms of resistance are complex and often multifactorial. Mechanisms include: (1) Activation of ATP-binding cassette (ABC) transporters, such as P-gp, which pump out lipophilic compounds that have entered a cell, (2) Activation of cytochrome p450 oxidases which can oxidize lipophilic agents to make them more hydrophilic and accessible for conjugation reaction with glucuronic acid, sulfate, or amino acids, and (3) Activation of glutathione transferase, which can conjugate xenobiotics. This review summarizes the evidence that secondary metabolites (SM) of plants, such as alkaloids, phenolics, and terpenoids can interfere with ABC transporters in cancer cells, parasites, bacteria, and fungi. Among the active natural products several lipophilic terpenoids [monoterpenes, diterpenes, triterpenes (including saponins), steroids (including cardiac glycosides), and tetraterpenes] but also some alkaloids (isoquinoline, protoberberine, quinoline, indole, monoterpene indole, and steroidal alkaloids) function probably as competitive inhibitors of P-gp, multiple resistance-associated protein 1, and Breast cancer resistance protein in cancer cells, or efflux pumps in bacteria (NorA) and fungi. More polar phenolics (phenolic acids, flavonoids, catechins, chalcones, xanthones, stilbenes, anthocyanins, tannins, anthraquinones, and naphthoquinones) directly inhibit proteins forming several hydrogen and ionic bonds and thus disturbing the 3D structure of the transporters. The natural products may be interesting in medicine or agriculture as they can enhance the activity of active chemotherapeutics or pesticides or even reverse multidrug resistance, at least partially, of adapted and resistant cells. If these SM are applied in combination with a cytotoxic or antimicrobial agent, they may reverse resistance in a synergistic fashion. PMID:22536197

  8. Synthesis of Some Novel Heterocyclic and Schiff Base Derivatives as Antimicrobial Agents.

    PubMed

    Azab, Mohamed E; Rizk, Sameh A; Amr, Abd El-Galil E

    2015-01-01

    Treatment of 2,3-diaryloxirane-2,3-dicarbonitriles 1a-c with different nitrogen nucleophiles, e.g., hydrazine, methyl hydrazine, phenyl hydrazine, hydroxylamine, thiosemicarbazide, and/or 2-amino-5-phenyl-1,3,4-thiadiazole, afforded pyrazole, isoxazole, pyrrolotriazine, imidazolothiadiazole derivatives 2-5, respectively. Reacting pyrazoles 2a-c with aromatic aldehydes and/or methyl glycinate produced Schiff's bases 7a-d and pyrazolo[3,4-b]-pyrazinone derivative 8, respectively. Treating 7 with ammonium acetate and/or hydrazine hydrate, furnished the imidazolopyrazole and pyrazolotriazine derivatives 9 and 10, respectively. Reaction of 8 with chloroacetic acid and/or diethyl malonate gave tricyclic compound 11 and triketone 12, respectively. On the other hand, compound 1 was reacted with active methylene precursors, e.g., acetylacetone and/or cyclopentanone producing adducts 14a,b which upon fusion with ammonium acetate furnished the 3-pyridone derivatives 15a,b, respectively. Some of newly synthesized compounds were screened for activity against bacterial and fungal strains and most of the newly synthesized compounds showed high antimicrobial activities. The structures of the new compounds were elucidated using IR, ¹H-NMR, (13)C-NMR and mass spectroscopy. PMID:26457697

  9. Two bacterial infection models in tree shrew for evaluating the efficacy of antimicrobial agents.

    PubMed

    Li, Sheng-An; Lee, Wen-Hui; Zhang, Yun

    2012-02-01

    Animal models are essential for the development of new anti-infectious drugs. Although some bacterial infection models have been established in rodents, small primate models are rare. Here, we report on two bacterial infection models established in tree shrew (Tupaia belangeri chinensis). A burnt skin infection model was induced by dropping 5×10(6) CFU of Staphylococcus aureus on the surface of a wound after a third degree burn. This dose of S. aureus caused persistent infection for 7 days and obvious inflammatory response was observed 4 days after inoculation. A Dacron graft infection model, 2×10(6) CFU of Pseudomonas aeruginosa also caused persistent infection for 6 days, with large amounts of pus observed 3 days after inoculation. These models were used to evaluate the efficacy of levofloxacin (LEV) and cefoperazone (CPZ), which reduced the viable bacteria in skin to 4log10 and 5log10 CFU/100 mg tissue, respectively. The number of bacteria in graft was significantly reduced by 4log10 CFU/mL treatment compared to the untreated group (P<0.05). These results suggest that two bacterial infection models were successfully established in tree shrew using P. aeruginosa and S. aureus. In addition, tree shrew was susceptible to P. aeruginosa and S. aureus, thus making it an ideal bacterial infection animal model for the evaluation of new antimicrobials. PMID:22345001

  10. Cationic Methacrylate Polymers as Topical Antimicrobial Agents against Staphylococcus aureus Nasal Colonization

    PubMed Central

    2015-01-01

    The in vitro and in vivo antimicrobial activity of primary ammonium ethyl methacrylate homopolymers (AEMPs) was investigated. AEMPs with different degrees of polymerization (DP = 7.7–12) were prepared by reversible addition–fragmentation chain-transfer (RAFT) polymerization. The AEMPs showed higher inhibitory effects against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), than Gram-negative bacteria. The AEMPs also showed potent anti-S. aureus activity in the presence of fetal bovine serum, whereas the activity of the antibiotic mupirocin was reduced under the same conditions. The AEMPs showed very little or no hemolytic activity. The cytotoxicity of AEMPs against mammalian cells HEp-2 and COS-7 was concentration-dependent, and the cell viability significantly decreased at higher polymer concentrations. The AEMPs significantly reduced the number of viable S. aureus cells in the nasal environment of cotton rats when compared to that of the control. This study demonstrates that AEMPs have potential for use in treating topical S. aureus infections. PMID:25010735

  11. Microwave assisted synthesis of some novel 2-pyrazoline derivatives as possible antimicrobial agents.

    PubMed

    Chawla, Rakesh; Sahoo, Ujjwal; Arora, Anshu; Sharma, Prabodh Chander; Radhakrishnan, Vijayaraj

    2010-01-01

    Some new [3-(4-phenyl)-5-phenyl-4,5-dihydropyrazol-1-yl](pyridine-4-yl)methanones and 3-substituted phenyl-5-substituted phenyl-4,5-dihydro-pyrazole-1-carbothioamides have been synthesized employing microwave techniques and evaluated for antimicrobial activity. Substituted acetophenones (1) were reacted with appropriately substituted benzaldehydes (2) in the presence of ethanol to furnish substituted chalcones (3a-f). These chalcones were further treated with isonicotinic acid hydrazide (INH) to afford substituted [3-(4-phenyl)-5-phenyl-4,5-dihydropyrazol-1-yl](pyridine-4-yl)methanones (4a-f). Reaction of these chalcones with thiosemicarbazide yielded substituted 3,5-diphenyl-4,5-dihydro-1H-pyrazole-1-carbothioamides (5a-f). The structures of newly synthesized compounds (4a-f) and (5a-f) have been confirmed by suitable spectroscopic techniques such as IR and 1H NMR. All the compounds were screened for their antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa and for antifungal activity against Candida albicans and Aspergillus niger The compounds exhibited moderate antibacterial and good antifungal activities. Compound 4b and 4d showed significant antifungal activity against A. niger and C. albicans, respectively. PMID:20210079

  12. Synthesis and characterization of novel organocobaloximes as potential catecholase and antimicrobial activity agents.

    PubMed

    Erdem-Tuncmen, Mukadder; Karipcin, Fatma; Sariboga, Bahtiyar

    2013-10-01

    An asymmetric, potentially bidentate dioxime ligand (H₂L) was formed by condensation of 4-biphenylchloroglyoxime and napthyl-1-amine. Two equivalents of H₂L were reacted with CoCl₂  · 6H₂O under appropriate conditions with deprotonation of the dioxime ligand. A series of new organocobaloxime derivatives of the type [CoR(HL)₂Py], [CoRL₂PyB₂F₄], and [CoRL₂Py(Cu(phen))₂] (H₂L = 4-(napthyl-1-amino)biphenylglyoxime; phen = 1,10-phenathroline; R = izopropyl and benzyl; Py = pyridine) were synthesized. The products were characterized by elemental analysis, molar conductance, FT-IR, ¹H NMR, and magnetic susceptibility measurements. Catecholase-like activity properties of all complexes were also studied. All complexes are catalysts for the oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butyl-1,2-benzoquinone in methanol. Antimicrobial activity studies of H₂L and the six complexes were carried out on standard strains (human pathogenic) of bacteria (Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Bacillus cereus, Enterococcus faecalis, Streptococcus pneumoniae, Listeria monocytogenes, Bacillus subtilis, Escherichia coli, Pseudominas aeruginosa, Salmonella typhi) and the yeast Candida albicans. The compounds showed a significant inhibition of the growth of the Gram-positive bacteria tested. Among the tested microorganisms, S. aureus was the most sensitive strain, especially to H₂L and its complexes. PMID:24003018

  13. Cationic methacrylate polymers as topical antimicrobial agents against Staphylococcus aureus nasal colonization.

    PubMed

    Thoma, Laura M; Boles, Blaise R; Kuroda, Kenichi

    2014-08-11

    The in vitro and in vivo antimicrobial activity of primary ammonium ethyl methacrylate homopolymers (AEMPs) was investigated. AEMPs with different degrees of polymerization (DP = 7.7-12) were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The AEMPs showed higher inhibitory effects against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), than Gram-negative bacteria. The AEMPs also showed potent anti-S. aureus activity in the presence of fetal bovine serum, whereas the activity of the antibiotic mupirocin was reduced under the same conditions. The AEMPs showed very little or no hemolytic activity. The cytotoxicity of AEMPs against mammalian cells HEp-2 and COS-7 was concentration-dependent, and the cell viability significantly decreased at higher polymer concentrations. The AEMPs significantly reduced the number of viable S. aureus cells in the nasal environment of cotton rats when compared to that of the control. This study demonstrates that AEMPs have potential for use in treating topical S. aureus infections. PMID:25010735

  14. Ruthenium (II) complexes of thiosemicarbazone: synthesis, biosensor applications and evaluation as antimicrobial agents.

    PubMed

    Yildirim, Hatice; Guler, Emine; Yavuz, Murat; Ozturk, Nurdan; Kose Yaman, Pelin; Subasi, Elif; Sahin, Elif; Timur, Suna

    2014-11-01

    A conformationally rigid half-sandwich organoruthenium (II) complex [(η(6)-p-cymene)RuClTSC(N-S)]Cl, (1) and carbonyl complex [Ru(CO)Cl(PPh3)2TSC(N-S)] (2) have been synthesized from the reaction of [{(η(6)-p-cymene)RuCl}2(μ-Cl)2] and [Ru(H)(Cl)(CO)(PPh3)3] with thiophene-2-carboxaldehyde thiosemicarbazon (TSC) respectively and both novel ruthenium (II) complexes have been characterized by elemental analysis, FT-IR and NMR spectroscopy. The peripheral TSC in the complexes acts as an electrochemical coupling unit providing the ability to carry out electrochemical deposition (ED) and to form an electro-deposited film on a graphite electrode surface. The biosensing applicability of complexes 1 and 2 was investigated by using glucose oxidase (GOx) as a model enzyme. Electrochemical measurements at -0.9V versus Ag/AgCl electrode by following the ED Ru(II) reduction/oxidation due to from the enzyme activity, in the presence of glucose substrate. The designed biosensor showed a very good linearity for 0.01-0.5mM glucose. The in vitro antimicrobial activities of complexes 1 and 2 were also investigated against nine bacterial strains and one fungus by the disc diffusion test method. No activity was observed against the Gram-negative strains and fungus, whereas complex 1 showed moderate antibacterial activities against Gram-positive bacterial strains. PMID:25280673

  15. Lasallia pustulata lichen as possible natural antigenotoxic, antioxidant, antimicrobial and anticancer agent.

    PubMed

    Kosanić, Marijana; Ranković, Branislav; Stanojković, Tatjana; Stošić, Ivana; Grujičić, Darko; Milošević-Djordjević, Olivera

    2016-08-01

    The methanol extract of the lichen Lasallia pustulata was tested for genotoxic, antioxidant, antimicrobial and anticancer activities. We did this using a cytokinesis block micronucleus (MN) assay on peripheral blood lymphocytes, by measuring free radical and superoxide anion scavenging activity, reducing power, determining of total phenolic compounds and determining the total flavonoid content, measuring the minimal inhibitory concentration by the broth microdilution method against five species of bacteria and five species of fungi and by using the microculture tetrazolium test on FemX (human melanoma) and LS174 (human colon carcinoma) cell lines. As a result of this study, we found that the methanol extract of L. pustulata did not modify the frequency of the MN and nuclear division index in comparison to untreated cells (p > 0.05). These results revealed that the methanol extract had moderate free radical scavenging activity with IC50 values of 395.56 μg/mL. Moreover, the extract tested had effective reducing power and superoxide anion radical scavenging. The values of the minimum inhibitory concentration against the tested microorganisms ranged from 0.625 to 20 mg/mL. In addition, the extract tested had strong anticancer activity against both cell lines with IC50 values of 46.67 and 71.71 μg/mL. PMID:25682053

  16. An in vitro method which assesses corneal epithelial toxicity due to antineoplastic, preservative and antimicrobial agents.

    PubMed

    Lazarus, H M; Imperia, P S; Botti, R E; Mack, R J; Lass, J H

    1989-01-01

    We developed an in vitro model for studying the cytotoxicity of pharmacologic agents on corneal epithelium employing 3H-thymidine incorporation. Primary rabbit corneal epithelial cell cultures were established, and the cells plated prior to each experiment. 3H-thymidine incorporation was measured after the addition of drug or vehicle to these confluent cells, and dose-response curves were generated. Marked inhibition of 3H-thymidine incorporation was reached at chemotherapeutic concentrations achieved clinically for cytosine arabinoside (10(-7) M), methotrexate (10(-3) M), and 5-fluorouracil (10(-6) M). A 10(-4) M concentration of 2-deoxycytidine, a naturally occurring competitive inhibitor of cytosine arabinoside, protected cells up to a concentration of 10(-5) M. We utilized these data to undertake an in vivo prophylaxis study in 13 leukemia patients receiving high-dose iv cytosine arabinoside. Topical deoxycytidine 10(-4) M and 1% prednisolone phosphate, given 12 hours prior to the start of antileukemic therapy, were effective in reducing symptoms and signs of keratitis; both were better than historical placebo-treated eyes. Ophthalmic preservatives were studied in vitro at concentrations used clinically: benzalkonium chloride (BAC) (0.004-0.02%) was the most toxic, thimerosal (TMS) (0.001-0.004%) intermediate, and chlorobutanol (CHB) (0.2-0.5%) the least toxic. Antiviral agents (final concentration) included: trifluridine (TFT) (1.0%), ethyldeoxuridine (EDU) (2.0%), and idoxuridine (IDU) (0.1%). Dose but not time-dependent concentrations of these 3 agents were noted to cause toxicity; however, (E)-5(2-bromovinyl)-2'-deoxyuridine (BVDU) (0.1%) was non-toxic. Similarly, tobramycin and amikacin were significantly less toxic than gentamicin and neomycin in this system. These in vitro cytotoxicity data correlate well with previous in vivo and pre-clinical corneal epithelial toxicity studies. Our model may be useful in the toxicologic study of future topical

  17. New antimicrobial agents as therapy for resistant gram-positive cocci.

    PubMed

    Lentino, J R; Narita, M; Yu, V L

    2008-01-01

    Vancomycin- and methicillin-resistant gram-positive cocci have emerged as an increasingly problematic cause of hospital-acquired infections. We conducted a literature review of newer antibiotics with activity against vancomycin-resistant and methicillin-resistant gram-positive cocci. Quinupristin/dalfopristin, linezolid, daptomycin, and tigecycline have in vitro activity for methicillin-resistant staphylococci and are superior to vancomycin for vancomycin-resistant isolates. Dalbavancin, telavancin, and oritavancin are new glycopeptides that have superior pharmacodynamic properties compared to vancomycin. We review the antibacterial spectrum, clinical indications and contraindications, pharmacologic properties, and adverse events associated with each of these agents. Daptomycin has rapid bactericidal activity for Staphylococcus aureus and is approved for use in bacteremia and right-sided endocarditis. Linezolid is comparable to vancomycin in patients with methicillin-resistant S. aureus (MRSA) pneumonia and has pharmacoeconomic advantages given its oral formulation. Quinupristin/dalfopristin is the drug of choice for vancomycin-resistant Enterococcus faecium infections but has no activity against Enterococcus faecalis. Tigecycline has activity against both enterococcus species and MRSA; it is also active against Enterobacteriaceae and anaerobes which allows for use in intra-abdominal and diabetic foot infections. A review of numerous in vitro and animal model studies shows that interaction between these newer agents and other antistaphylococcal agents for S. aureus are usually indifferent (additive). PMID:17899228

  18. [Susceptibility of clinically-isolated bacteria strains to respiratory quinolones and evaluation of antimicrobial agent efficacy by Monte Carlo simulation].

    PubMed

    Kosaka, Tadashi; Yamada, Yukiji; Kimura, Takeshi; Kodama, Mai; Fujitomo, Yumiko; Masaki, Nakanishi; Toshiaki, Komori; Keisuke, Shikata; Fujita, Naohisa

    2016-02-01

    Respiratory quinolones (RQs) are broad-spectrum antimicrobial agents used for the treatment of a wide variety of community-acquired and nosocomial infections. However, bacterial resistance to quinolones has been on the increase. In this study, we investigated the predicted efficacy of RQs for various strains of 9 bacterial species clinically isolated at our university hospital using the Monte Carlo simulation (MCS) method based on pharmacokinetics/pharmacodynamics modeling. In addition, the influence of the patients' renal function on the efficacy of RQs was evaluated. We surveyed antimicrobial susceptibility testing of 9 bacterial species (n = number of strains) [Streptococcus pneumoniae (n = 15), Streptococcus pyogenes (n = 14), Streptococcus agalactiae (n = 19), methicillin-susceptible Staphylococcus aureus (MSSA) (n = 24), Escherichia coli (n = 35), Haemophilus influenzae (n = 17), Klebsiella pneumoniae (n = 14), Pseudomonas aeruginosa (n = 31), and Moraxella catarrhalis (n = 11)] to 4 RQs [garenoxacin (GRNX), levofloxacin (LVFX), sitafloxacin (STFX), and moxifloxacin (MFLX)]. We found that compared with the other RQs, Gram-positive cocci was most resistant to LVFX, and that the minimum inhibitory concentration (MIC₉₀) values for S. pneumoniae, S. pyogenes, S. agalactiae, and MSSA were high (2, 16, > 16, and 8 µg/mL, respectively). In regard to Gram-negative rods, the susceptibility of E. coli to RQs was found to be decreased, with the MIC₉₀ values of GRNX, LVFX, STFX, and MFLX being > 16, 16, 1, and 16 µg/mL, respectively. MCS revealed that the target attainment rate of the area under the unbound concentration-time curve divided by the MIC₉₀ (ƒ · AUC/MIC ratio), against S. pneumoniae was 86.9-100%, but against E. coli was low (52.1-66.2%). The ƒ · AUC/MIC target attainment rate of LVFX against S. pneumoniae, S. pyogenes, and S. agalactiae tended to decrease due to increased creatinine clearance, and that of LVFX and STFX against MSSA also

  19. Essential oil from black currant buds as chemotaxonomy marker and antimicrobial agent.

    PubMed

    Ethorđević, Boban S; Pljevljakušić, Ðorđević S; Savikin, Katarina P; Stević, Tatjana R; Bigović, Dubravka J

    2014-08-01

    Dormant buds are recognized as valuable side product of the blackcurrant cultivation. Four blackcurrant varieties cultivated in Serbia, i.e., Ben Sarek, Ometa, Ben Lomond, and Ben Nevis, were evaluated for the content, chemical composition, and antimicrobial activity of their bud essential oils. The oil yields of buds harvested during two different growth periods ranged from 1.2-2.0%, and the variety Ometa had the highest yield among the tested varieties. GC-FID and GC/MS analysis of the oils allowed the identification of eight main components, i.e., α-pinene (1.6-5.4%), sabinene (1.9-38.4%), δ-car-3-ene (13.0-50.7%), β-phellandrene (2.9-18.0%), terpinolene (6.6-11.9%), terpinen-4-ol (0.9-6.6%), β-caryophyllene (3.8-10.4%), and α-humulene (0.2-4.1%). In addition, the similarity degree of the essential-oil compositions of buds harvested from the upper and lower parts of the shrubs was investigated by hierarchical clustering. All essential oils originating from the same genotype were grouped in the same cluster, indicating the reliability of essential oils as chemotaxonomic markers. For more detailed chemotaxonomic investigations, the three compounds with the greatest variance were chosen, i.e., sabinene, δ-car-3-ene, and β-phellandrene, which proved to be efficient for the variety distinction. Factor analysis showed that the essential-oil composition as chemotaxonomic marker in blackcurrants was more reliable for variety Ben Sarek than for variety Ben Nevis. Moreover, it was demonstrated that the essential oils had very strong inhibitory activity against all tested microorganisms. Fungi were more sensitive than bacteria; indeed their growth was completely inhibited at much lower concentrations. In comparison to commercial antibiotics, significantly lower concentrations of the oils were necessary for the complete inhibition of fungal growth. PMID:25146766

  20. Disinfection of maxillofacial silicone elastomer using a novel antimicrobial agent: recombinant human beta-defensin-3.

    PubMed

    Shi, Y; Song, W; Feng, Z H; Zhao, Y T; Li, F; Tian, Y; Zhao, Y M

    2009-04-01

    Maxillofacial silicone elastomer, when used as a prosthesis, is in contact with wound surfaces and mucosa, and tends to be contaminated with microorganisms from a patient's saliva and blood. The aim of the study was to evaluate the efficacy of human beta-defensin-3 (HBD3) on the reduction of two resistant bacteria species from the surface of maxillofacial silicone elastomer. HBD3 cDNA was amplified from total RNA, which had been extracted from human gingival epithelium by means of reverse-transcription polymerase chain reaction (RT-PCR). Following this, the cDNA fragments were recombined in a prokaryotic expression vector. The constructed expression vectors pET-32a/HBD3 were transformed into Escherichia coli to obtain recombinant protein. After protein purification and refolding, the product was verified in classic antimicrobial experiments against Staphylococcus aureus and Candida albicans. Specimens made of silicone elastomer A-2186, which had been contaminated with S. aureus or C. albicans, were immersed in rHBD3 or 5.25% sodium hypochlorite (a positive control) for 5 min, 10 min, 30 min, or 60 min. The active recombinant HBD3 obtained in the current study eliminated the S. aureus and C. albicans microorganism from the surface of the maxillofacial elastomer after a 30-min immersion. There was no statistically significant difference between the rHBD3 group and the sodium hypochlorite 5.25% group. In conclusion, rHBD3 exhibits antibacterial activity against oral pathogenic strains that adhere to maxillofacial elastomer, and may, thus, contribute to the prevention of infections caused by S. aureus and C. albicans. PMID:18841402

  1. Thiazole-Based Thiazolidinones as Potent Antimicrobial Agents. Design, Synthesis and Biological Evaluation.

    PubMed

    Haroun, Micheline; Tratrat, Cristof; Tsolaki, Evangelia; Geronikaki, Athina

    2016-01-01

    As a part of our ongoing project on the design and synthesis of new thiazole derivatives with antimicrobial activity, fourteen new ethyl 2-(2-((E)-((Z)-5-(4-benzyliden)- 4-oxothiazolidin-2-yliden)amino-4-yl)acetates, carrying halogens, methoxy and other groups were synthesized. Compounds were tested against eight Gram positive and negative bacteria as well as eight yeasts and mold by microdilution assay. All compounds showed good activity against all bacteria tested with MIC ranging between 2.3-39.8 µmol/ml x 10(-2) and MBC of 9.2-79.6 µmol/ml x 10(-2). As reference drugs Ampicillin (MIC 24.8-74.4 and MBC 37.2-124.0 µmol/ml x 10(-2)) and Streptomycin (MIC 4,3-17.2 and MBC 8.6-51.6 µmol/ml x 10(-2)) were used. The best activity was observed for 4-bromo derivative. All tested compounds showed excellent antifungal activity against all fungi tested with MIC in the range between 0.3-38.6 µmol/ml x 10(-2) and MFC range of 0.6-77.2 µmol/ml x 10(-2), better than that of reference drugs, Ketoconazole (MIC 38.0-475.0 and MFC 95.0-570 µmol/ml x 10(-2)) and Bifonazole (MIC 48.0-64.0 and MFC 64.0-80.0 µmol/ml x 10(-2)). The best activity was observed for 3-nitro derivative. It was found that among the 5-arylidene derivatives the inhibitory effect appears to be dependent on the substitution at the benzene ring. Fourteen new ethyl 2-(2-((E)-((Z)-5-(4-benzyliden)-4-oxothiazolidin-2-yliden)amino-4-yl)acetates were synthesized and evaluated for antibacterial and antifungal activity. PMID:26632442

  2. Organic residues as immobilizing agents in aided phytostabilization: (II) effects on soil biochemical and ecotoxicological characteristics.

    PubMed

    Alvarenga, P; Palma, P; Gonçalves, A P; Fernandes, R M; de Varennes, A; Vallini, G; Duarte, E; Cunha-Queda, A C

    2009-03-01

    Sewage sludge (SS), municipal solid waste compost, and garden waste compost (GWC) were used as immobilizing agents in aided phytostabilization of an acid metal-contaminated soil affected by mining activities. The organic residues were applied at 25, 50 and 100 Mg ha(-1) (dry weight basis) and perennial ryegrass (Lolium perenne L.) was used as a "green cover". We studied the effects of the treatments on soil phytotoxicity and enzymatic activities, and on the composition and toxicity of the soil leachate towards Vibrio fischeri and Daphnia magna. Application of SS led to the greatest values of dehydrogenase, acid phosphatase, beta-glucosidase, protease and urease activities, corresponding to the greatest overall microbial and biochemical activity in amended soils. Conversely, GWC did not increase these enzymatic activities, relative to the unamended soil, or enhance ryegrass growth. Cellulase activity increased with increasing application rates of the amendments tested, but decreased at the highest SS application rate. The organic amendments were able to suppress soil toxicity to levels that did not affect D. magna, when applied at 50 and 100 Mg ha(-1), but SS, at the same application rates, increased the soil leachate toxicity towards V. fischeri. Moreover, ryegrass showed some phytotoxic symptoms when 100 Mg ha(-1) of SS were applied. This study showed the importance of an integrated evaluation of soil quality on remediation processes. Although SS immobilized trace metals and corrected soil acidity, improving soil biochemical status, when used at high application rates it led to toxicity of soil leachate towards V. fischeri, decreased soil cellulase activity and impaired ryegrass growth. PMID:19091381

  3. In-house validation of PremiTest, a microbiological screening test with solvent extraction, for the detection of antimicrobial residues in poultry muscles.

    PubMed

    Magalhães, C G; De Paiva, C R; Botelho, B G; De Oliveira, A M G; De Souza, L F; Nonaka, C V; Santos, K V; Farias, L M; Carvalho, M A R

    2012-01-01

    PremiTest, a microbial inhibition test for the screening of antimicrobial residues, was validated according to the criteria established by Decision 2002/657/EC. Sensitivity, detection capability (CCβ), specificity, selectivity, robustness and applicability were evaluated. The methodology involves the technique of solvent extraction, which increases the detection capability of the test for a wider range of antibiotics. The following CCβ values in poultry muscle were found: penicillin G ≤ 12.5 µg kg(-1), total sulfonamides ≤ 75 µg kg(-1), erythromycin 75 µg kg(-1) and lincomycin 50 µg kg(-1). The detection capability of chlortetracycline was equal to its maximum residue limit (100 µg kg(-1)) and the method did not detect gentamicin (1000 µg kg(-1)), for which no MRL is established in poultry muscle. Specificity evaluated in relation to different analytes and matrices did not detect any interferences in the tests results; whilst the robustness showed that the pH neutralisation point of the extract affects the analytical results and the kits' performance. Only the screening of tetracyclines requires the analysis of extracts without pH neutralisation. The results of the validation process showed that this method is acceptable for screening β-lactam, sulfonamide and macrolide antimicrobial groups in the National Residues and Contaminants Control Programme (PNCRC), and that for this it is fit for purpose. PMID:22059477

  4. Mechanism of antibacterial action of a synthetic peptide with an Ala-peptoid residue based on the scorpion-derived antimicrobial peptide IsCT.

    PubMed

    Lim, Shin Saeng; Yoon, Sang-Pil; Park, Yoonkyoung; Zhu, Wan Long; Park, Il-Seon; Hahm, Kyung-Soo; Shin, Song Yub

    2006-09-01

    A novel bacterial cell-selective antimicrobial peptide, IsCT-P (ILKKIWKPIKKLF-NH(2)), was designed based on the scorpion-derived alpha-helical antimicrobial peptide, IsCT. Here, we investigated the effect of substituting Pro(8) of IsCT-P with the Ala-peptoid residue (N-methylglycine) on the peptide's structure and mechanism of action. Circular dichroism analysis revealed that the modified peptide, IsCT-a, has a much lower alpha-helicity than IsCT-P in membrane mimicking conditions, suggesting the peptoid residue provides much more structural flexibility than the proline residue. IsCT-a was also much less effective than IsCT-P at causing leakage of fluorescent dye entrapped within negatively charged vesicles and at dissipating the membrane potential of Staphylococcus aureus. Collectively, our results suggest that the antibacterial action of IsCT-a is due to the inhibition of intracellular targets rather than the disruption and depolarization of bacterial cell membranes. PMID:16871429

  5. Platismatia glaucia and Pseudevernia furfuracea lichens as sources of antioxidant, antimicrobial and antibiofilm agents

    PubMed Central

    Mitrovic, Tatjana; Stamenkovic, Slaviša; Cvetkovic, Vladimir; Radulovic, Niko; Mladenovic, Marko; Stankovic, Milan; Topuzovic, Marina; Radojevic, Ivana; Stefanovic, Olgica; Vasic, Sava; Comic, Ljiljana

    2014-01-01

    The antioxidative, antimicrobial and antibiofilm potentials of acetone, ethyl acetate and methanol extracts of lichen species Platismatia glauca and Pseudevernia furfuracea were evaluated. The phytochemical analysis by GC, GC/MS and NMR revealed caperatic acid, atraric acid, atranorin and chloroatranorin as the predominant compounds in Platismatia glauca. Atraric acid, olivetoric acid, atranorin and chloroatranorin were the major constituents in Pseudevernia furfuracea. The strong antioxidant capacities of the Platismatia glauca and Pseudevernia furfuracea extracts were assessed by their total phenolic and flavonoid contents and DPPH scavenging activities. The methanol extracts of both species exhibited the strongest antioxidant activities with the highest IC50 value for Pseudevernia furfuracea (95.33 µg/mL). The lichen extracts demonstrated important antibacterial activities against 11 bacterial strains with detectable MIC values from 0.08 mg/mL to 2.5 mg/mL for Platismatia glauca and from 0.005 mg/mL to 2.5 mg/mL for Pseudevernia furfuracea. While the antibacterial activities of Pseudevernia furfuracea were solvent–independent, the acetone and ethyl acetate extracts of Platismatia glauca showed higher antibacterial activities compared to its methanol extract. The methanol extracts of both species demonstrated significant antifungal activities against 9 fungal strains with detectable MIC values from 0.04 mg/mL to 2.5 mg/mL. The best antifungal activities were determined against Candida species in Pseudevernia furfuracea extracts with remarkable MIC values which were lower than the MIC values of the positive contol fluconazole. The acetone and ethyl acetate extracts of Platismatia glauca showed better antibiofilm activities on Staphylococcus aureus and Proteus mirabilis with BIC value at 0.63 mg/mL then its methanol extract. On the other hand, the methanol extract of Pseudevernia furfuracea was more potent with BIC value at 1.25 mg/mL on Staphylococcus aureus

  6. Platismatia glaucia and Pseudevernia furfuracea lichens as sources of antioxidant, antimicrobial and antibiofilm agents.

    PubMed

    Mitrovic, Tatjana; Stamenkovic, Slaviša; Cvetkovic, Vladimir; Radulovic, Niko; Mladenovic, Marko; Stankovic, Milan; Topuzovic, Marina; Radojevic, Ivana; Stefanovic, Olgica; Vasic, Sava; Comic, Ljiljana

    2014-01-01

    The antioxidative, antimicrobial and antibiofilm potentials of acetone, ethyl acetate and methanol extracts of lichen species Platismatia glauca and Pseudevernia furfuracea were evaluated. The phytochemical analysis by GC, GC/MS and NMR revealed caperatic acid, atraric acid, atranorin and chloroatranorin as the predominant compounds in Platismatia glauca. Atraric acid, olivetoric acid, atranorin and chloroatranorin were the major constituents in Pseudevernia furfuracea. The strong antioxidant capacities of the Platismatia glauca and Pseudevernia furfuracea extracts were assessed by their total phenolic and flavonoid contents and DPPH scavenging activities. The methanol extracts of both species exhibited the strongest antioxidant activities with the highest IC50 value for Pseudevernia furfuracea (95.33 µg/mL). The lichen extracts demonstrated important antibacterial activities against 11 bacterial strains with detectable MIC values from 0.08 mg/mL to 2.5 mg/mL for Platismatia glauca and from 0.005 mg/mL to 2.5 mg/mL for Pseudevernia furfuracea. While the antibacterial activities of Pseudevernia furfuracea were solvent-independent, the acetone and ethyl acetate extracts of Platismatia glauca showed higher antibacterial activities compared to its methanol extract. The methanol extracts of both species demonstrated significant antifungal activities against 9 fungal strains with detectable MIC values from 0.04 mg/mL to 2.5 mg/mL. The best antifungal activities were determined against Candida species in Pseudevernia furfuracea extracts with remarkable MIC values which were lower than the MIC values of the positive contol fluconazole. The acetone and ethyl acetate extracts of Platismatia glauca showed better antibiofilm activities on Staphylococcus aureus and Proteus mirabilis with BIC value at 0.63 mg/mL then its methanol extract. On the other hand, the methanol extract of Pseudevernia furfuracea was more potent with BIC value at 1.25 mg/mL on Staphylococcus aureus and

  7. The effect of colouring agent on the physical properties of glass ceramic produced from waste glass for antimicrobial coating deposition

    NASA Astrophysics Data System (ADS)

    Juoi, J. M.; Ayoob, N. F.; Rosli, Z. M.; Rosli, N. R.; Husain, K.

    2016-07-01

    Domestic waste glass is utilized as raw material for the production of glass ceramic material (GCM) via sinter crystallisation route. The glass ceramic material in a form of tiles is to be utilized for the deposition of Ag-TiO2 antimicrobial coating. Two types of soda lime glass (SLG) that are non-coloured and green SLG are utilised as main raw materials during the batch formulation in order to study the effect of colouring agent (Fe2O3) on the physical and mechanical properties of glass ceramic produced. Glass powder were prepared by crushing bottles using hammer milled with milling machine and sieved until they passed through 75 µm sieve. The process continues by mixing glass powder with ball clay with ratio of 95:5 wt. %, 90:10 wt. % and 85:15 wt. %. Each batch mixture was then uniaxial pressed and sintered at 800°C, 825 °C and 850 °C. The physical and mechanical properties were then determined and compared between those produced from non-coloured and green coloured SLG in order to evaluate the effect of colouring agent (Fe2O3) on the GCM produced. The optimum properties of non-coloured SLG is produced with smaller ball clay content (10 wt. %) compared to green SLG (15 wt. %). The physical properties (determined thru ASTM C373) of the optimized GCM produced from non-coloured SLG and green SLG are 0.69 % of porosity, 1.92 g/cm3 of bulk density, 0.36 % of water absorption; and 1.96 % of porosity, 2.69 g/cm3 of bulk density, 0.73 % of water absorption; respectively. Results also indicate that the most suitable temperature in producing GCM from both glasses with optimized physical and mechanical properties is at 850 °C.

  8. Aliphatic acid-conjugated antimicrobial peptides--potential agents with anti-tumor, multidrug resistance-reversing activity and enhanced stability.

    PubMed

    Deng, Xin; Qiu, Qianqian; Ma, Ke; Wang, Xuekun; Huang, Wenlong; Qian, Hai

    2015-07-28

    Compared with traditional therapeutics, antimicrobial peptides as novel anti-tumor agents have prominent advantages of higher specificity and circumvention of multi-drug resistance. In a previous study, we found that B1, an antimicrobial peptide derived from Cathelicidin-BF15, presented specific anti-tumor activity against several tumor cells. Since aliphatic chain-conjugated peptides have shown ameliorative activity and stability, we conjugated aliphatic acids with different lengths to the amino terminal of B1. All the conjugated peptides exhibited improved anti-tumor activity over B1. Further investigations revealed that the peptides were capable of disrupting the cell membrane, stimulating cytochrome c release into the cytosol, which results in apoptosis. The peptides also acted against multidrug resistant cells and had multidrug resistance-reversing effects. Additionally, conjugation of aliphatic acid enhanced the peptide stability in plasma. In summary, aliphatic acid-modified peptides might be promising anti-tumor agents in the future. PMID:26083110

  9. Susceptibility to antimicrobial agents among bovine mastitis pathogens isolated from North American dairy cattle, 2002-2010.

    PubMed

    Lindeman, Cynthia J; Portis, Ellen; Johansen, Lacie; Mullins, Lisa M; Stoltman, Gillian A

    2013-09-01

    Approximately 8,000 isolates of Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Staphylococcus aureus, and Escherichia coli, isolated by 25 veterinary laboratories across North America between 2002 and 2010, were tested for in vitro susceptibility to beta-lactam, macrolide, and lincosamide drugs. The minimal inhibitory concentrations (MICs) of the beta-lactam drugs remained low against most of the Gram-positive strains tested, and no substantial changes in the MIC distributions were seen over time. Of the beta-lactam antimicrobial agents tested, only ceftiofur showed good in vitro activity against E. coli. The MICs of the macrolides and lincosamides also remained low against Gram-positive mastitis pathogens. While the MIC values given by 50% of isolates (MIC50) for erythromycin and pirlimycin and the streptococci were all low (≤0.5 µg/ml), the MIC values given by 90% of isolates (MIC90) were higher and more variable, but with no apparent increase over time. Staphylococcus aureus showed little change in erythromycin susceptibility over time, but there may be a small, numerical increase in pirlimycin MIC50 and MIC90 values. Overall, the results suggest that mastitis pathogens in the United States and Canada have not shown any substantial changes in the in vitro susceptibility to beta-lactam, macrolide, and lincosamide drugs tested over the 9 years of the study. PMID:23907894

  10. Bactericidal effects of antimicrobial agents on epithelial cell-associated Pseudomonas aeruginosa.

    PubMed

    Hirakata, Yoichi; Yano, Hisakazu; Arai, Kazuaki; Kitagawa, Miho; Hatta, Masumitsu; Kunishima, Hiroyuki; Kaku, Mitsuo

    2012-06-01

    It is not clear whether antipseudomonal agents can kill cell-associated bacteria within a short time. Madin-Darby canine kidney (MDCK) and A549 cells were infected with Pseudomonas aeruginosa ATCC 27853 and PAO1 and the bactericidal activity of ceftazidime, imipenem, meropenem, gentamicin, and ciprofloxacin against the organisms was investigated. In both MDCK and A549 cells, β-lactams could not kill epithelial cell-associated bacteria within 2 h. Gentamicin at concentrations ≤32 μg/ml killed more than 99% of epithelial cell-associated bacteria. Ciprofloxacin at 0.5 μg/ml killed more than 99.9% of MDCK cell-associated bacteria. Ciprofloxacin has the strongest and most rapid bactericidal activity against epithelial cell-associated bacteria, which may be explained by the combination of potent in-vitro bactericidal activity and high penetration ability into epithelial cells. PMID:22116462

  11. 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.

  12. Antimicrobial Agents Produced by Marine Aspergillus terreus var. africanus Against Some Virulent Fish Pathogens.

    PubMed

    Barakat, Khouloud M; Gohar, Yousry M

    2012-09-01

    Screening of fungal isolates collected from different locations of Alexandria coast, Egypt, was carried out to obtain new biologically active metabolites against some virulent fish pathogens (Edwardsiella tarda, Aeromonas hydrophila, Vibrio ordalli and Vibrio angularuim). Among 26 fungal isolates, Aspergillus terreus var. africanus was identified as the most potent isolate. Production of the bioactive material was optimized using response surface methodology including fermentation media, incubation period, temperature, pH, and thermo-stability. Spectral properties of the gas chromatography/mass spectrum of the ethyl acetate crude extract were determined. Partially purified components of the crude extract were chromatographically separated and bioassayed. Out of ten separated compounds, five were with considerable antibacterial agent. The bio-toxicity of crude showed a slight toxicity against the brine shrimp Artemia salina (LC50 = 1,500 μg/l). Antibacterial activity of the crude was compared with some known standard antibiotics and found to be superior over many where its MIC against some pathogen reached 1 μg/ml. PMID:23997326

  13. The use of resazurin as a novel antimicrobial agent against Francisella tularensis.

    PubMed

    Schmitt, Deanna M; O'Dee, Dawn M; Cowan, Brianna N; Birch, James W-M; Mazzella, Leanne K; Nau, Gerard J; Horzempa, Joseph

    2013-01-01

    The highly infectious and deadly pathogen, Francisella tularensis, is classified by the CDC as a Category A bioterrorism agent. Inhalation of a single bacterium results in an acute pneumonia with a 30-60% mortality rate without treatment. Due to the prevalence of antibiotic resistance, there is a strong need for new types of antibacterial drugs. Resazurin is commonly used to measure bacterial and eukaryotic cell viability through its reduction to the fluorescent product resorufin. When tested on various bacterial taxa at the recommended concentration of 44 μM, a potent bactericidal effect was observed against various Francisella and Neisseria species, including the human pathogens type A F. tularensis (Schu S4) and N. gonorrhoeae. As low as 4.4 μM resazurin was sufficient for a 10-fold reduction in F. tularensis growth. In broth culture, resazurin was reduced to resorufin by F. tularensis. Resorufin also suppressed the growth of F. tularensis suggesting that this compound is the biologically active form responsible for decreasing the viability of F. tularensis LVS bacteria. Replication of F. tularensis in primary human macrophages and non-phagocytic cells was abolished following treatment with 44 μM resazurin indicating this compound could be an effective therapy for tularemia in vivo. PMID:24367766

  14. In vitro activity of antimicrobial agents against oxacillin resistant staphylococci with special reference to Staphylococcus haemolyticus.

    PubMed

    Chaudhury, A; Kumar, A G

    2007-01-01

    One hundred and sixty seven isolates of staphylococci isolated from the inpatients of a tertiary care referral hospital in South India were speciated and activity of oxacillin, glycopeptides, linezolid and quinupristin/dalfopristin against these isolates was tested by broth microdilution method. Of the 114 coagulase negative staphylococci (CoNS), 49.1 % were S. haemolyticus, isolated predominantly from urine (64.6%), while the rest belonged to 11 other species. More than half the isolates of S. aureus (52.8%) and 68.4% of the CoNS were oxacillin resistant. All the strains were uniformly susceptible to vancomycin, linezolid and quinupristin/dalfopristin; but 25.6% isolates of S. haemolyticus showed reduced susceptibility to teicoplanin (MIC: 8-16 mg/L). Our study demonstrates the high prevalence of oxacillin resistance among hospital isolates of S. aureus and CoNS in India. Vancomycin, along with the newer agents like linezolid and quinupristin/dalfopristin remains the drug of choice for treating multi drug resistant staphylococcal infections. PMID:17377353

  15. The fatty acid synthase inhibitor triclosan: repurposing an anti-microbial agent for targeting prostate cancer

    PubMed Central

    Sadowski, Martin C.; Pouwer, Rebecca H.; Gunter, Jennifer H.; Lubik, Amy A.; Quinn, Ronald J.; Nelson, Colleen C.

    2014-01-01

    Inhibition of FASN has emerged as a promising therapeutic target in cancer, and numerous inhibitors have been investigated. However, severe pharmacological limitations have challenged their clinical testing. The synthetic FASN inhibitor triclosan, which was initially developed as a topical antibacterial agent, is merely affected by these pharmacological limitations. Yet, little is known about its mechanism in inhibiting the growth of cancer cells. Here we compared the cellular and molecular effects of triclosan in a panel of eight malignant and non-malignant prostate cell lines to the well-known FASN inhibitors C75 and orlistat, which target different partial catalytic activities of FASN. Triclosan displayed a superior cytotoxic profile with a several-fold lower IC50 than C75 or orlistat. Structure-function analysis revealed that alcohol functionality of the parent phenol is critical for inhibitory action. Rescue experiments confirmed that end product starvation was a major cause of cytotoxicity. Importantly, triclosan, C75 and orlistat induced distinct changes to morphology, cell cycle, lipid content and the expression of key enzymes of lipid metabolism, demonstrating that inhibition of different partial catalytic activities of FASN activates different metabolic pathways. These finding combined with its well-documented pharmacological safety profile make triclosan a promising drug candidate for the treatment of prostate cancer. PMID:25313139

  16. Minimum inhibitory concentrations of selected antimicrobial agents for Moraxella bovoculi associated with infectious bovine keratoconjunctivitis.

    PubMed

    Angelos, John A; Ball, Louise M; Byrne, Barbara A

    2011-05-01

    Infectious bovine keratoconjunctivitis (IBK) has been associated with ocular infections by Moraxella bovis, the established etiologic agent of IBK, and more recently, Moraxella bovoculi, a recently described species of Moraxella. To assist in designing rational treatment regimens for M. bovoculi infections associated with IBK, the in vitro susceptibilities of 57 M. bovoculi field isolates cultured from eyes of cattle with IBK in California from 2002 through 2007 were determined. The minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC(90)) of the following 18 antibiotics tested in the present study were: danofloxacin and enrofloxacin: ≤0.12 µg/ml; ampicillin and ceftiofur: ≤0.25 µg/ml; penicillin: 0.25 µg/ml; gentamicin: ≤1 µg/ml; chlortetracycline, oxytetracycline, and tiamulin: 1 µg/ml; florfenicol: 0.5 µg/ml; trimethoprim-sulfamethoxazole: ≤2/38 µg/ml; clindamycin: 2 µg/ml; neomycin and tilmicosin: ≤4 µg/ml; tulathromycin: 4 µg/ml; spectinomycin and tylosin: 16 µg/ml; and sulfadimethoxine: >256 µg/ml. The low MIC(90) of these M. bovoculi isolates suggests that commonly used antibiotics for treatment of IBK associated with M. bovis should also be effective against M. bovoculi. PMID:21908289

  17. Bacteriophage PBC1 and its endolysin as an antimicrobial agent against Bacillus cereus.

    PubMed

    Kong, Minsuk; Ryu, Sangryeol

    2015-04-01

    Bacillus cereus is an opportunistic human pathogen responsible for food poisoning and other, nongastrointestinal infections. Due to the emergence of multidrug-resistant B. cereus strains, the demand for alternative therapeutic options is increasing. To address these problems, we isolated and characterized a Siphoviridae virulent phage, PBC1, and its lytic enzymes. PBC1 showed a very narrow host range, infecting only 1 of 22 B. cereus strains. Phylogenetic analysis based on the major capsid protein revealed that PBC1 is more closely related to the Bacillus clarkii phage BCJA1c and phages of lactic acid bacteria than to the phages infecting B. cereus. Whole-genome comparison showed that the late-gene region, including the terminase gene, structural genes, and holin gene of PBC1, is similar to that from B. cereus temperate phage 250, whereas their endolysins are different. Compared to the extreme host specificity of PBC1, its endolysin, LysPBC1, showed a much broader lytic spectrum, albeit limited to the genus Bacillus. The catalytic domain of LysPBC1 when expressed alone also showed Bacillus-specific lytic activity, which was lower against the B. cereus group but higher against the Bacillus subtilis group than the full-length protein. Taken together, these results suggest that the virulent phage PBC1 is a useful component of a phage cocktail to control B. cereus, even with its exceptionally narrow host range, as it can kill a strain of B. cereus that is not killed by other phages, and that LysPBC1 is an alternative biocontrol agent against B. cereus. PMID:25595773

  18. The human milk protein-lipid complex HAMLET sensitizes bacterial pathogens to traditional antimicrobial agents.

    PubMed

    Marks, Laura R; Clementi, Emily A; Hakansson, Anders P

    2012-01-01

    The fight against antibiotic resistance is one of the most significant challenges to public health of our time. The inevitable development of resistance following the introduction of novel antibiotics has led to an urgent need for the development of new antibacterial drugs with new mechanisms of action that are not susceptible to existing resistance mechanisms. One such compound is HAMLET, a natural complex from human milk that kills Streptococcus pneumoniae (the pneumococcus) using a mechanism different from common antibiotics and is immune to resistance-development. In this study we show that sublethal concentrations of HAMLET potentiate the effect of common antibiotics (penicillins, macrolides, and aminoglycosides) against pneumococci. Using MIC assays and short-time killing assays we dramatically reduced the concentrations of antibiotics needed to kill pneumococci, especially for antibiotic-resistant strains that in the presence of HAMLET fell into the clinically sensitive range. Using a biofilm model in vitro and nasopharyngeal colonization in vivo, a combination of HAMLET and antibiotics completely eradicated both biofilms and colonization in mice of both antibiotic-sensitive and resistant strains, something each agent alone was unable to do. HAMLET-potentiation of antibiotics was partially due to increased accessibility of antibiotics to the bacteria, but relied more on calcium import and kinase activation, the same activation pathway HAMLET uses when killing pneumococci by itself. Finally, the sensitizing effect was not confined to species sensitive to HAMLET. The HAMLET-resistant respiratory species Acinetobacter baumanii and Moraxella catarrhalis were all sensitized to various classes of antibiotics in the presence of HAMLET, activating the same mechanism as in pneumococci. Combined these results suggest the presence of a conserved HAMLET-activated pathway that circumvents antibiotic resistance in bacteria. The ability to activate this pathway may extend

  19. 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

  20. The effect of pathophysiology on pharmacokinetics in the critically ill patient--concepts appraised by the example of antimicrobial agents.

    PubMed

    Blot, Stijn I; Pea, Federico; Lipman, Jeffrey

    2014-11-20

    Critically ill patients are at high risk for development of life-threatening infection leading to sepsis and multiple organ failure. Adequate antimicrobial therapy is pivotal for optimizing the chances of survival. However, efficient dosing is problematic because pathophysiological changes associated with critical illness impact on pharmacokinetics of mainly hydrophilic antimicrobials. Concentrations of hydrophilic antimicrobials may be increased because of decreased renal clearance due to acute kidney injury. Alternatively, antimicrobial concentrations may be decreased because of increased volume of distribution and augmented renal clearance provoked by systemic inflammatory response syndrome, capillary leak, decreased protein binding and administration of intravenous fluids and inotropes. Often multiple conditions that may influence pharmacokinetics are present at the same time thereby excessively complicating the prediction of adequate concentrations. In general, conditions leading to underdosing are predominant. Yet, since prediction of serum concentrations remains difficult, therapeutic drug monitoring for individual fine-tuning of antimicrobial therapy seems the way forward. PMID:25038549

  1. Molecular genetic basis of antimicrobial agent resistance in Mycobacterium tuberculosis: 1998 update.

    PubMed

    Ramaswamy, S; Musser, J M

    1998-01-01

    Knowledge of the molecular genetic basis of resistance to antituberculous agents has advanced rapidly since we reviewed this topic 3 years ago. Virtually all isolates resistant to rifampin and related rifamycins have a mutation that alters the sequence of a 27-amino-acid region of the beta subunit of ribonucleic acid (RNA) polymerase. Resistance to isoniazid (INH) is more complex. Many resistant organisms have mutations in the katG gene encoding catalase-peroxidase that result in altered enzyme structure. These structural changes apparently result in decreased conversion of INH to a biologically active form. Some INH-resistant organisms also have mutations in the inhA locus or a recently characterized gene (kasA) encoding a beta-ketoacyl-acyl carrier protein synthase. Streptomycin resistance is due mainly to mutations in the 16S rRNA gene or the rpsL gene encoding ribosomal protein S12. Resistance to pyrazinamide in the great majority of organisms is caused by mutations in the gene (pncA) encoding pyrazinamidase that result in diminished enzyme activity. Ethambutol resistance in approximately 60% of organisms is due to amino acid replacements at position 306 of an arabinosyltransferase encoded by the embB gene. Amino acid changes in the A subunit of deoxyribonucleic acid gyrase cause fluoroquinolone resistance in most organisms. Kanamycin resistance is due to nucleotide substitutions in the rrs gene encoding 16S rRNA. Multidrug resistant strains arise by sequential accumulation of resistance mutations for individual drugs. Limited evidence exists indicating that some drug resistant strains with mutations that severely alter catalase-peroxidase activity are less virulent in animal models. A diverse array of strategies is available to assist in rapid detection of drug resistance-associated gene mutations. Although remarkable advances have been made, much remains to be learned about the molecular genetic basis of drug resistance in Mycobacterium tuberculosis. It is

  2. Effective Phages as Green Antimicrobial Agents Against Antibiotic-Resistant Hospital Escherichia coli

    PubMed Central

    Rahmani, Rana; Zarrini, Gholamreza; Sheikhzadeh, Farzam; Aghamohammadzadeh, Naser

    2015-01-01

    Background: Bacteriophages are viruses that attack bacteria and lead to their lysis in an efficient and highly specific manner. These natural enemies of bacteria were used as therapeutic agents before the advent of antibiotics. Currently, with the rapid spread of multi-drug resistant bacteria, phage therapy can be an effective alternative treatment for antibiotic resistant bacteria. Objectives: This study evaluated the effectiveness of bacteriophages in removing antibiotic-resistant clinical Escherichia coli strains in vitro and in vivo. Patients and Methods: Different samples were taken from bed sore and foot ulcers of patients with diabetes. E. coli strains were isolated and identified by standard methods. The antibiogram was ascertained using the Kirby Bauer disc diffusion method for ten antibiotics. The bacteriophages were isolated from environmental water samples. They were exposed to the host bacteria by the double-layer agar technique (DLA) to observe plaques. Cross reaction of the phages on test E. coli strains was performed to determine broader-spectrum phages. Phage TPR7 was selected for animal trials. Five groups of mice including a control group, bacterial group, phage group, antibiotic therapy group and phage therapy group, were examined. Results: Ten E. coli strains were isolated from hospital samples. They showed high resistance to the used antibiotics. An effective bacteriophage was isolated for each strain. The cross-reaction showed phages which affect more than six E. coli strains. They can be a good choice for clinical therapeutic use. In animal trials the group challenged with phages after being infected showed similar results as the group treated with gentamicin after being infected. In both groups infection was removed after 48 hours. Conclusions: According to the results, six strains were resistant to six or seven antibiotics and all strains were at least resistant to two antibiotics. However, for each of these resistant bacteria one

  3. Correlation between in vitro and in vivo activity of antimicrobial agents against gram-negative bacilli in a murine infection model.

    PubMed Central

    Fantin, B; Leggett, J; Ebert, S; Craig, W A

    1991-01-01

    We studied the relationship between in vitro susceptibility tests (MICs, MBCs) and in vivo activity of tobramycin, pefloxacin, ceftazidime, and imipenem against 15 gram-negative bacilli from five different species in a murine thigh infection model. Complete dose-response curves were determined for each antimicrobial agent against each strain, and three parameters of in vivo activity were defined: maximal attainable antimicrobial effect (i.e., reduction in log10 CFU per thigh compared with untreated controls) at 24 h (Emax), total dose required to reach 50% of maximal effect (P50), and total dose required to achieve a bacteriostatic effect (static dose). Pefloxacin demonstrated the greatest Emax (P less than 0.05). Tobramycin was the most potent antimicrobial agent, as indicated by its having the lowest static dose/MIC ratio (P less than 0.002). Log10 P50s and static doses correlated significantly with log10 MICs or MBCs for the 15 strains of each antibiotic (P less than 0.01) except imipenem (P greater than 0.50). The greater potency of imipenem against the three Pseudomonas aeruginosa strains than against strains of the family Enterobacteriaceae (P less than 0.01) explained this lack of correlation. A longer duration of postantibiotic effect for imipenem against P. aeruginosa (P = 0.02) contributed to its increased potency against these strains. We conclude that in vitro susceptibility tests correlated well with in vivo activity in this animal model and that variations in potency among the four antimicrobial agents could be explained by differences in pharmacokinetics or pharmacodynamic activity. PMID:1929302

  4. cgMolluscidin, a novel dibasic residue repeat rich antimicrobial peptide, purified from the gill of the Pacific oyster, Crassostrea gigas.

    PubMed

    Seo, Jung-Kil; Lee, Min Jeong; Nam, Bo-Hye; Park, Nam Gyu

    2013-08-01

    A 5.5 kDa antimicrobial peptide consisting of 55 amino acids, cgMolluscidin, was purified from the acidified gill extract of the Pacific oyster, Crassostrea gigas, by ion-exchange and C18 reversed-phase high performance liquid chromatography. By comparing the N-terminal amino acid sequences and the molecular weight of this peptide with those of other known antimicrobial peptides, it has been revealed that this peptide had no homology with any known peptides. cgMolluscidin showed potent antimicrobial activity against both Gram-positive bacteria, including Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus (minimal effective concentrations [MECs]; 1.3-31.3 μg/mL), and Gram-negative bacteria, including Escherichia coli, Salmonella enterica, and Vibrio parahaemolyticus ([MECs]; 0.4-2.3 μg/mL), without hemolytic activity. However, cgMolluscidin did not show any significant activity against Candida albicans. The deduced amino acid sequence of the cgMolluscidin showed no hit in public protein databases, while the nucleotide sequence had a 99% homology (E value = 0) with only the unknown ESTs sequenced by C. gigas EST project. Tissue distribution of the cgMolluscidin mRNA suggests that it is constitutively expressed as a mature form in a non-tissue-specific manner. The cgMolluscidin mRNA expression level was significantly up-regulated at 12 h (2.8-fold) post injection with Vibrio sp. This peptide is highly basic and contains several dibasic residue repeats including Lysine-Lysine or Lysine-Arginine in the sequence, but may not form an ordered structure. These results suggest that cgMolluscidin might be an oyster-specific novel antimicrobial peptide. PMID:23711469

  5. Comparative study of three screening tests, two microbiological tube tests, and a multi-sulphonamide ELISA kit for the detection of antimicrobial and sulphonamide residues in eggs.

    PubMed

    Gaudin, V; Hedou, C; Rault, A; Sanders, P; Verdon, E

    2009-04-01

    The screening of antimicrobial residues in eggs is an especially important subject. Three different commercial kits for the screening of sulphonamides and other antimicrobials in eggs were validated in accordance with Decision 2002/657/EC: one enzyme-linked immunoabsorbant assay (ELISA) kit multi-sulphonamides (from RAISIO Diagnostics) and two microbiological tests (a Premi test from DSM and an Explorer kit from Zeu-Inmunotec). The false-positive rates were lower than 2% for all kits. The detection capabilities (CCbeta) have to be as low as possible for banned substances and lower than the maximum residue limit (MRL) when MRLs have been set. The sensitivity of the Premi test was better than that of the Explorer test, probably because of the dilution of the eggs before the Explorer test was used. The CCbeta values towards most of the tested sulphonamides were satisfactory with the Premi test (< or = 100 microg kg(-1)). Performance in a proficiency test for the detection of sulphonamides in eggs with the Premi test confirmed these results. The detection capabilities of tetracycline and doxycycline were at the level of the MRL or twice the MRL maximum. The detection capabilities for chlortetracycline and oxytetracycline were higher (four to six times the MRL). The detection capabilities for amoxicillin, neomycin, tylosin and erythromycin were lower than their respective MRLs. Detection capabilities for sulphonamides were much lower for the ELISA kit than for microbiological tests. The ELISA kit could be recommended for the targeted screening of sulphonamides in eggs. On the other hand, the Explorer and Premi tests could be used as wide screening tests allowing the detection of most of the antimicrobial families. PMID:19680917

  6. Characterization of the bioactive metabolites from a plant growth-promoting rhizobacteria and their exploitation as antimicrobial and plant growth-promoting agents.

    PubMed

    George, Emrin; Kumar, S Nishanth; Jacob, Jubi; Bommasani, Bhaskara; Lankalapalli, Ravi S; Morang, P; Kumar, B S Dileep

    2015-05-01

    A plant growth-promoting bacterial strain, PM 105, isolated from a tea plantation soil from the North Eastern region of India was identified as Pseudomonas aeruginosa through classical and 16S ribosomal DNA (rDNA) gene sequencing. Further studies with this strain confirmed broad spectrum antifungal activity against ten human and plant pathogenic fungal pathogens viz. Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus tubingensis, Candida albicans, Colletotrichum gloeosporioides, Fusarium oxysporum, Pencillium expansum, Rhizoctonia solani, Trichophyton rubrum besides growth-promoting property in cowpea (Vigna unguiculata) and pigeon pea (Cajanus cajan). However, no antibacterial property was exhibited by this strain against the four test bacterial pathogens tested in agar overlay method. The crude bioactive metabolites produced by this strain were isolated with three different solvents that exhibited significant antimicrobial and plant growth-promoting activity. Chloroform extract recorded significant antimicrobial and plant growth-promoting activity. Three major compounds viz. 1-hydroxyphenazine, pyocyanin, and phenazine-1-carboxamide were purified and characterized from crude extracts of this strain by various spectral data. The purified compounds recorded prominent antimicrobial activity but failed to establish the plant growth promotion activity in test crop plants under gnotobiotic conditions. Pyocyanin recorded significant antimicrobial activity, and best activity was recorded against T. rubrum (29 mm), followed by P. expansum (28 mm). These results suggest the use of PM 105 as plant growth-promoting agent in crop plants after successful field trials. PMID:25832181

  7. Antimicrobial susceptibilities of Escherichia coli isolates as agents of community-acquired urinary tract infection (2008–2014)

    PubMed Central

    Yılmaz, Nisel; Ağuş, Neval; Bayram, Arzu; Şamlıoğlu, Pınar; Şirin, M. Cem; Derici, Yeşer Karaca; Hancı, Sevgi Yılmaz

    2016-01-01

    Objective Urinary tract infections (UTIs) are among the most frequently seen community-acquired infections worldwide. E. coli causes 90% of urinary system infections. To guide the empirical therapy, the resistance pattern of E. coli responsible for community-acquired UTI was evaluated throughout a seven-year period in this study. Material and methods The urine cultures of patients with urinary tract infections admitted to outpatient clinics between 1st January 2008 and 31st December 2014 were analyzed. Presence of ≥105 colony-forming units/mL in urine culture media was considered as significant for UTI. Isolated bacteria were identified by standard laboratory techniques or automated system VITEK2 (BioMerieux, France) and BD PhoenixTM 100 (BD, USA), as required. Antibiotic susceptibility testing was performed by Kirby-Bauer disk diffusion method using Clinical Laboratory Standard Institute (CLSI) criteria. Results A total of 13281 uropathogens were isolated. Overall E. coli accounted for 8975 (67%) of all isolates. Resistance rates of E. coli to antimicrobial agents was demonstrated to be as follows: ampicillin 66.9%, cefazolin 30.9%, cefuroxime 30.9%, ceftazidime 14.9%, cefotaxime 28%, cefepime 12%, amoxicillin-clavulanic acid 36.9%, trimethoprim-sulfamethoxazole (TMP-SXT) 20%, ciprofloxacin 49.9%, amikacin 0.3%, gentamycin 24%, nitrofurantoin 0.9%, and fosfomycin 4.3%. There was no resistance to imipenem nor meropenem. The frequency of ESBL-producing E. coli strains was 24%. Conclusion It is concluded that fosfomycin and nitrofurantoin are appropriate empirical therapy for community-acquired UTI empirical therapy, but the fluoroquinolones and the TMP-SXT shall not be used in the emprical treatment of UTI at this stage. In conclusion, as resistance rates show regional differences, it is necessary to regularly examine regional resistance rates to determine the appropriate empiric antibiotic treatment and national antibiotic usage policies must be reorganized

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

    PubMed

    Haggard, Derik E; Noyes, Pamela D; Waters, Katrina M; Tanguay, Robert L

    2016-10-01

    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 120hours post-fertilization (hpf) and the concentration where 80% of the animals had mortality or morbidity at 120hpf (EC80) was calculated. Transcriptomic profiling was conducted on embryos exposed to the EC80 (7.37μM). 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. PMID:27538710

  9. 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. PMID:21282489

  10. [Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1996), III. Secular changes in susceptibility].

    PubMed

    Kumamoto, Y; Tsukamoto, T; Hirose, T; Yokoo, A; Shigeta, S; Takahashi, T; Shiraiwa, Y; Ogiwara, M; Yoshida, H; Imafuku, Y; Murai, M; Watanabe, K; Uchida, H; Kobayashi, Y; Matsuda, S; Fujime, M; Fujita, K; Igari, J; Oguri, T; Yamaguchi, K; Matsumoto, T; Kashitani, F; Kaku, M; Ooe, H; Mochida, C

    1998-03-01

    Susceptibilities to various antimicrobial agents were examined for Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella spp., and Pseudomonas aeruginosa that were isolated from patients with urinary tract infections (UTIs) in 10 hospitals during June 1996 to May 1997, and the results were compared with those obtained during the same period in earlier years. 1. E. faecalis Among E. faecalis strains, those with high susceptibilities to ampicillin and minocycline appeared to have decreased in the latest study period. 2. S. aureus To almost antimicrobial agents, S. aureus isolated from uncomplicated UTIs showed low susceptibilities. But the MIC50s of those agents for S. aureus from complicated UTIs have changed better state. Particularly, the MIC50s of imipenem and clindamycin were 0.125 microgram/ml or below in the latest period for the first time in our history. 3. E. coli The susceptibilities to piperacillin and quinolones of E. coli isolated from uncomplicated UTIs were better than those isolated from complicated UTIs. 4. Klebsiella spp. The susceptibilities to almost antimicrobial agents of Klebsiella spp. have been better during the latest period, compared to those during period of 1995-1996, but to ofloxacin and ciprofloxacin have appeared to have been lower. 5. P. aeruginosa The susceptibilities to quinolones of P. aeruginosa have been better during the latest period compared those during periods of 1995-1996. But, the susceptibilities to cefozopran, carbapenems and monobactams of P. aeruginosa isolated from complicated UTIs appeared to have been lower. These susceptibility changes should be utilized in determining clinical treatments. PMID:9597551

  11. The role of spices and lactic acid bacteria as antimicrobial agent to extend the shelf life of metata ayib (traditional Ethiopian spiced fermented cottage cheese).

    PubMed

    Geremew, Tsehayneh; Kebede, Ameha; Andualem, Berhanu

    2015-09-01

    Spices and lactic acid bacteria have natural antimicrobial substances and organic compounds having antagonistic activity against microorganisms. The objective of this study was to investigate the role of spices and lactic acid bacteria as antimicrobial agent to extend the shelf life of metata ayib. Antimicrobial activities of spices and lactic acid bacteria (LAB) filtrates were determined by agar well diffusion method against E. coli, S. aureus, S. flexneri and S. peumoniae. Aantimicrobial activity of garlic was found to be the most effective against all the tested pathogens. Inhibition zones of garlic extract against all pathogens was significantly (P ≤ 0.05) greater than the remaining spice extracts. Inhibition zones (12.50 ± 1.00 to 15.50 ± 1.00 mm) of ginger and R. graveolens ethanol extracts against all tested pathogens were significantly (P ≤ 0.05) greater than the remaining solvent extracts. Inhibition zone of O. basilicum ethanol extract against all pathogenic bacteria was significantly (p ≤ 0.05) greater than hexane and acetone extracts. Lactobacillus isolates were shown the highest antimicrobial activity than the other LAB isolates against all pathogens. The synergistic effect of spices together with LAB might be contributed a lot to preserve and extend shelf life of metata ayib. Their antimicrobial activity can reduce the risk of spoilage and pathogenesis. The possible reason of LAB isolates was may be due to production of lactic acid, acetic acid and secondary metabolites like bacteriocins. Aseptic processing of traditional cottage cheese (ayib) is by far needed to minimize risks associated during consumption of metata ayib. PMID:26344979

  12. USING REDUCING AGENTS TO ELIMINATE CHLORINE DIOXIDE AND CHLORITE ION RESIDUALS IN DRINKING WATER

    EPA Science Inventory

    In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind. Water and Sewer Utility is engaged in a pilot-plant investigation to compare chlorine dioxide and ozone pretreatment. As a result of increased speculation that the total residual c...

  13. Synthesis of silver nanoparticles using Dioscorea bulbifera tuber extract and evaluation of its synergistic potential in combination with antimicrobial agents

    PubMed Central

    Ghosh, Sougata; Patil, Sumersing; Ahire, Mehul; Kitture, Rohini; Kale, Sangeeta; Pardesi, Karishma; Cameotra, Swaranjit S; Bellare, Jayesh; Dhavale, Dilip D; Jabgunde, Amit; Chopade, Balu A

    2012-01-01

    . Conclusion This is the first report on the synthesis of silver nanoparticles using D. bulbifera tuber extract followed by an estimation of its synergistic potential for enhancement of the antibacterial activity of broad spectrum antimicrobial agents. PMID:22334779

  14. [Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1995). III. Differences in susceptibilities from previous years].

    PubMed

    Kumamoto, Y; Tsukamoto, T; Hirose, T; Yokoo, A; Hikichi, Y; Shigeta, S; Takahashi, T; Shiraiwa, Y; Ogiwara, M; Yoshida, H; Imafuku, Y; Murai, M; Watanabe, K; Uchida, H; Kobayashi, Y; Matsuda, S; Fujime, M; Fujita, K; Igari, J; Oguri, T; Kosakai, N; Yamaguchi, K; Matsumoto, T; Kashitani, F; Mochida, C

    1997-04-01

    Susceptibilities to various antimicrobial agents were examined for Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa that were isolated from patients with urinary tract infections (UTIs) in 11 hospitals during June, 1995 through May, 1996, and the results were compared with those obtained during the same period in earlier years. 1. Macrolide resistant E. faecalis isolated from uncomplicated UTIs during the latest study period appeared to have increased compared to those in previous study periods. More than 50% of the isolated E. faecalis during the latest study period were resistant to macrolide antibiotics, for the first time in our history. 2. No obvious changes were observed through the years for susceptibilities of S. aureus to various antimicrobial agents. Vancomycin (VCM) showed the highest activity against S. aureus, with MICs below 2 micrograms/ml or below. 3. Among E. coli strains, those with low susceptibilities to quinolones appeared to have increased over the years with MIC90 changed from between 0.125 microgram/ml or below and 0.5 microgram/ml in the 1989-1990 period to between 8 micrograms/ml and 128 micrograms/ml in the latest study period. 4. Klebsiella spp. showed higher resistance to most antimicrobial agents during periods of 1993-1994 and 1994-1995, but somewhat lower resistance during period of 1995-1996. No resistant Klebsiella spp. were detected from uncomplicated UTIs during the latest study period. 5. Among P. aeruginosa isolates from complicated UTIs, resistance isolates to gentamicin appeared to be increasing over the years. Resistant strains to quinolones were isolated at lower frequencies during periods of 1991-1994, but higher frequency was observed in the latest period, and MIC50s were between 0.5 and 4 micrograms/ml during 1991-1994, but were 16-32 micrograms/ml during 1995-1996. These susceptibility changes should be utilized in determining clinical treatments. PMID:9192248

  15. V-type nerve agents phosphonylate ubiquitin at biologically relevant lysine residues and induce intramolecular cyclization by an isopeptide bond.

    PubMed

    Schmidt, Christian; Breyer, Felicitas; Blum, Marc-Michael; Thiermann, Horst; Worek, Franz; John, Harald

    2014-08-01

    Toxic organophosphorus compounds (e.g., pesticides and nerve agents) are known to react with nucleophilic side chains of different amino acids (phosphylation), thus forming adducts with endogenous proteins. Most often binding to serine, tyrosine, or threonine residues is described as being of relevance for toxicological effects (e.g., acetylcholinesterase and neuropathy target esterase) or as biomarkers for post-exposure analysis (verification, e.g., albumin and butyrylcholinesterase). Accordingly, identification of novel protein targets might be beneficial for a better understanding of the toxicology of these compounds, revealing new bioanalytical verification tools, and improving knowledge on chemical reactivity. In the present study, we investigated the reaction of ubiquitin (Ub) with the V-type nerve agents Chinese VX, Russian VX, and VX in vitro. Ub is a ubiquitous protein with a mass of 8564.8 Da present in the extra- and intracellular space that plays an important physiological role in several essential processes (e.g., proteasomal degradation, DNA repair, protein turnover, and endocytosis). Reaction products were analyzed by matrix-assisted laser desorption/ionization-time-of-flight- mass spectrometry (MALDI-TOF MS) and μ-high-performance liquid chromatography online coupled to UV-detection and electrospray ionization MS (μHPLC-UV/ESI MS). Our results originally document that a complex mixture of at least mono-, di, and triphosphonylated Ub adducts was produced. Surprisingly, peptide mass fingerprint analysis in combination with MALDI and ESI MS/MS revealed that phosphonylation occurred with high selectivity in at least 6 of 7 surface-exposed lysine residues that are essential for the biological function of Ub. These reaction products were found not to age. In addition, we herein report for the first time that phosphonylation induced intramolecular cyclization by formation of an isopeptide bond between the ε-amino group of a formerly phosphonylated

  16. Evaluation of certain veterinary drug residues in food.

    PubMed

    2009-01-01

    This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of residues of certain veterinary drugs in food and to recommend maximum levels for such residues in food. The first part of the report considers general principles regarding the evaluation of veterinary drugs within the terms of reference of the Joint FAO/WHO Expert Committee on Food Additives (JECFA), including a hypothesis-driven decision tree approach for the safety evaluation of residues of veterinary drugs; comments on the Committee for Veterinary Products for Medicinal Use reflection paper on the new approach developed by JECFA for exposure and maximum residue limit (MRL) assessment of residues; residues of veterinary drugs in honey and possible approaches to derive MRLs for this commodity; comments on a paper entitled "Risk-assessment policies: Differences among jurisdictions"; and the use of no-observed-effect level (NOEL) and no-observed-adverse-effect level (NOAEL) in JECFA assessments. Summaries follow of the Committee's evaluations of toxicological and residue data on a variety of veterinary drugs: three antimicrobial agents (avilamycin, tilmicosin, tylosin), one anthelminthic (triclabendazole), one production aid (melengestrol acetate), two antimicrobial agents and production aids (monensin and narasin), a glucocarticosteroid (dexamethasone) and an antimicrobial agent and contaminant (malachite green). Annexed to the report is a summary of the Committee's recommendations on these drugs, including acceptable daily intakes (ADIs) and proposed MRLs. PMID:20112498

  17. In vitro susceptibility of e.faecalis and c.albicans isolates from apical periodontitis to common antimicrobial agents, antibiotics and antifungal medicaments

    PubMed Central

    Yoldas, Oguz; Yilmaz, Sehnaz; Akcimen, Beril; Seydaoglu, Gulsah; Kipalev, Arzu; Koksal, Fatih

    2012-01-01

    The aim of this study was to evaluate in vitro antimicrobial activity of 4 antibiotic agents (for E.faecalis) and 4 antifungal agents (for C.albicans) by agar dilution method. Additionally, modified strip diffusion method was used for detection of in vitro antimicrobial activities of 5% NaOCl, 2.5% NaOCl, 17% EDTA and 2% CHX and agar diffusion method for detection of in vitro susceptibilities of three intracanal medicaments for 18 E.faecalis and 18 C.albicans isolates from primary and secondary root canal infection. Isolates were recovered from 231 endodontic samples of patients, with the need of root canal treatment and retreatment. All tested E.faecalis isolates showed resistance to antibiotics. For irrigation solutions, 2% CHX was more effective in eliminating E.faecalis but 5% NaOCl showed larger inhibition zone than 2.5% NaOCl, 17% EDTA and 2% CHX. For intracanal medication, Ca(OH)2-CHX worked efficiently in killing E.faecalis isolates compared to Ca(OH)2-Steril saline solution, Ca(OH)2-Glycerin. For C.albicans, 18 isolates were susceptible to amphotericin B, nistatin, fluconazole but showed resistance to ketoconazole. 5% NaOCl was more effective in eliminating and produced larger inhibition zone compared to 2.5% NaOCl, 17% EDTA and 2% CHX. Ca(OH)2-Glycerin intracanal medication was better in eliminating C.albicans isolates and produced larger inhibition zone compared to other Ca(OH)2 medicaments. Key words:E.faecalis, C.albicans, antimicrobial, antibiotic, antifungal. PMID:24558517

  18. Functional Roles of Aromatic Residues and Helices of Papiliocin in its Antimicrobial and Anti-inflammatory Activities

    PubMed Central

    Lee, Eunjung; Kim, Jin-Kyoung; Jeon, Dasom; Jeong, Ki-Woong; Shin, Areum; Kim, Yangmee

    2015-01-01

    A cecropin-like peptide, papiliocin, isolated from the swallowtail butterfly Papilio xuthus, possesses high selectivity against gram-negative bacteria. Since Trp2 and Phe5 are highly conserved residues in cecropin-like peptides, we investigated the role of Trp2 and Phe5 in antibacterial activity. Substitution of Trp2 and Phe5 in papiliocin with Ala (papiliocin-2A and papiliocin-5A) revealed that Trp2 is a key residue in its antibacterial activities. In order to understand the structural requirements for papiliocin function and to design shorter, but more potent, peptide antibiotics, we designed papiliocin constructs, PapN (residues Arg1-Ala22 from the N-terminal amphipathic helix). PapN exhibited significant broad-spectrum antibacterial activities without cytotoxicity. Bactericidal kinetics of peptides against E.coli showed that papiliocin completely and rapidly killed E.coli in less than 10 minutes at 2× MIC concentration, while papiliocin-2A and papiliocin-5A killed four times more slowly than papiliocin. The PapN series peptides permeabilized bacterial membranes less effectively than papiliocin, showing no antibacterial activities in an hour. The results imply that the Trp2 and Phe5 in the amphipathic N-terminal helix are important in the rapid permeabilization of the gram-negative bacterial membrane. The hydrophobic C-terminal residues permeabilize the hydrophobic bacterial cell membrane synergistically with these aromatic residues, providing selectivity against gram-negative bacteria. PMID:26156126

  19. In vitro activity of orally administered antimicrobial agents against Haemophilus influenzae recovered from children monitored longitudinally in a group day-care center.

    PubMed

    George, M J; Kitch, B; Henderson, F W; Gilligan, P H

    1991-10-01

    To determine whether the prevalence of resistance to commonly used oral antimicrobial agents varied over time, we compared the in vitro susceptibilities of 217 strains of Haemophilus influenzae recovered from nasopharyngeal secretions of children in a day-care center studied longitudinally between 1979 and 1987. The overall rate of beta-lactamase production in these strains was 18%, with rates of 57% in type b isolates (n = 21) and 14% in non-type b isolates (n = 196). The percentages of isolates for which MICs were less than or equal to 1.0 micrograms/ml for amoxicillin alone, amoxicillin in combination with clavulanic acid, and cefuroxime alone were 82, 92, and 93%, respectively. The percentage of strains for which cefaclor MICs were less than or equal to 1.0 micrograms/ml was only 0.5%. Isolates for which chloramphenicol MICs were greater than 2.0 micrograms/ml or for which trimethoprim-sulfamethoxazole MICs were greater than 0.5/9.5 micrograms/ml were uncommon: 1 and less than 1%, respectively. High concentrations of erythromycin alone and in combination with sulfisoxazole were required to inhibit the majority of test strains; there was no evidence of erythromycin-sulfisoxazole synergy. In vitro susceptibility to commonly used oral antimicrobial agents remained at a constant level when H. influenzae isolates collected from children in a day-care center during 1979 through 1983 were compared with strains collected during 1984 through 1987. PMID:1759814

  20. TiO2 nanotube arrays deposited on Ti substrate by anodic oxidation and their potential as a long-term drug delivery system for antimicrobial agents

    NASA Astrophysics Data System (ADS)

    Moseke, Claus; Hage, Felix; Vorndran, Elke; Gbureck, Uwe

    2012-05-01

    Nanotube arrays on medical titanium surfaces were fabricated by two different anodization methods and their potential for storage and release of antimicrobial substances was evaluated. The treatment of the Ti surfaces in fluoride containing electrolytes on water as well as on polyethylene glycol basis led to the formation of TiO2 nanotubes with up to 6.54 μm length and average diameters of up to 160 nm. Drug release experiments with the model antibiotic vancomycin and with antibacterial silver ions showed that the increased surface area of the anodized samples enabled them to be loaded with up to 450% more active agent than the untreated Ti surfaces. Significant surface-dependent differences in the release kinetics of vancomycin were observed. In comparison to surfaces anodized in an aqueous electrolyte, the release of the antibiotic from surfaces anodized in an electrolyte based on ethylene glycol was significantly retarded, with a release of noticeable amounts over a period of more than 300 days. Loading of nanotube surfaces fabricated in aqueous electrolyte with silver ions revealed increased amounts of adsorbed silver by up to 230%, while the release kinetics showed significant differences in comparison to untreated Ti. It was concluded that nanotube arrays on favored medical implant materials have a high potential for loading with antimicrobial agents and also provide the possibility of tailored release kinetics by variation of anodization parameters.

  1. Harnessing the multifunctionality in nature: a bioactive agent release system with self-antimicrobial and immunomodulatory properties.

    PubMed

    Özçelik, Hayriye; Vrana, Nihal Engin; Gudima, Alexandru; Riabov, Vladimir; Gratchev, Alexei; Haikel, Youssef; Metz-Boutigue, Marie-Hélène; Carradò, Adele; Faerber, Jacques; Roland, Thierry; Klüter, Harald; Kzhyshkowska, Julia; Schaaf, Pierre; Lavalle, Philippe

    2015-09-16

    Major problems with biomedical devices in particular implants located in nonsterile environments concern: (i) excessive immune response to the implant, (ii) development of bacterial biofilms, and (iii) yeast and fungi infections. An original multifunctional coating that addresses all these issues concomitantly is developed. A new exponentially growing polyelectrolyte multilayer film based on polyarginine (PAR) and hyaluronic acid (HA) is designed. The films have a strong inhibitory effect on the production of inflammatory cytokines released by human primary macrophage subpopulations. This could reduce potential chronic inflammatory reaction following implantation. Next, it is shown that PAR, due to its positive charges, has an antimicrobial activity in film format against Staphylococcus aureus for 24 h. In order to have a long-term antimicrobial activity, a precursor nanoscale silver coating is deposited on the surface before adding the PAR/HA films. Moreover, the PAR/HA films can be easily further functionalized by embedding antimicrobial peptides, like catestatin (CAT), a natural host defense peptide. This PAR/HA+CAT film proves to be effective as an antimicrobial coating against yeast and fungi and its cytocompatibility is also assessed. Finally, this all-in-one system constitutes an original strategy to limit inflammation and prevents bacteria, yeast, and fungi infections. PMID:26379222

  2. Antimicrobial Activity of Lippia Species from the Brazilian Semiarid Region Traditionally Used as Antiseptic and Anti-Infective Agents

    PubMed Central

    Pinto, Cristiana da Purificação; Rodrigues, Velize Dias; Pinto, Fernanda da Purificação; Pinto, Renata da Purificação; Uetanabaro, Ana Paula Trovatti; Pinheiro, Carla Santos Ribeiro; Gadea, Suzana Ferreira Magalhães; Silva, Tânia Regina dos Santos; Lucchese, Angélica Maria

    2013-01-01

    Lippia origanoides Kunth, Lippia alnifolia Schauer, and Lippia thymoides Martius and Schauer are shrubs used in the traditional Brazilian medicine as antiseptics, as well as in the treatment of infectious diseases. This study was designed to investigate the antibacterial and antifungal activities of the methanolic extracts of these species, as new potential sources of antimicrobial drugs. The antimicrobial activity of methanolic extracts was investigated against resistant yeasts and bacteria by agar disk diffusion. Then, the MIC determination of the most active species and its fractions in hexane, dichloromethane, ethyl acetate, and water was performed. By the agar diffusion assay, all species were active against at least two microorganisms, giving evidence to support their use in the popular medicine. L. origanoides leaves exhibited the widest antimicrobial action, inhibiting the growth of two Gram-positive bacteria and two yeasts; this activity was also confirmed by the MIC evaluation. The fractionation of L. origanoides crude extracts improved the activity in spectrum and intensity. The results obtained in this study indicate that L. origanoides may be a promising alternative in the treatment of bacterial and fungal infections and in the seeking of new antimicrobial drugs. PMID:24109492

  3. Efficacy of Oral Vancomycin in Preventing Recurrent Clostridium difficile Infection in Patients Treated With Systemic Antimicrobial Agents.

    PubMed

    Van Hise, Nicholas W; Bryant, Alex M; Hennessey, Erin K; Crannage, Andrew J; Khoury, Jad A; Manian, Farrin A

    2016-09-01

    We compared rates of recurrent Clostridium difficile infection in patients receiving or not receiving oral vancomycin prophylaxis with systemic antimicrobial therapy. The incidence of C. difficile infection was significantly lower in patients receiving prophylaxis (4.2% vs 26.6% in those without prophylaxis; odds ratio, 0.12; 95% confidence interval, .04-.4; P < .001). PMID:27318333

  4. Key Residues of Outer Membrane Protein OprI Involved in Hexamer Formation and Bacterial Susceptibility to Cationic Antimicrobial Peptides

    PubMed Central

    Chang, Ting-Wei; Wang, Chiu-Feng; Huang, Hsin-Jye; Wang, Iren; Hsu, Shang-Te Danny

    2015-01-01

    Antimicrobial peptides (AMPs) are important components of the host innate defense mechanism against invading pathogens. Our previous studies have shown that the outer membrane protein, OprI from Pseudomonas aeruginosa or its homologue, plays a vital role in the susceptibility of Gram-negative bacteria to cationic α-helical AMPs (Y. M. Lin, S. J. Wu, T. W. Chang, C. F. Wang, C. S. Suen, M. J. Hwang, M. D. Chang, Y. T. Chen, Y. D. Liao, J Biol Chem 285:8985–8994, 2010, http://dx.doi.org/10.1074/jbc.M109.078725; T. W. Chang, Y. M. Lin, C. F. Wang, Y. D. Liao, J Biol Chem 287:418–428, 2012, http://dx.doi.org/10.1074/jbc.M111.290361). Here, we obtained two forms of recombinant OprI: rOprI-F, a hexamer composed of three disulfide-bridged dimers, was active in AMP binding, while rOprI-R, a trimer, was not. All the subunits predominantly consisted of α-helices and exhibited rigid structures with a melting point centered around 76°C. Interestingly, OprI tagged with Escherichia coli signal peptide was expressed in a hexamer, which was anchored on the surface of E. coli, possibly through lipid acids added at the N terminus of OprI and involved in the binding and susceptibility to AMP as native P. aeruginosa OprI. Deletion and mutation studies showed that Cys1 and Asp27 played a key role in hexamer formation and AMP binding, respectively. The increase of OprI hydrophobicity upon AMP binding revealed that it undergoes conformational changes for membrane fusion. Our results showed that OprI on bacterial surfaces is responsible for the recruitment and susceptibility to amphipathic α-helical AMPs and may be used to screen antimicrobials. PMID:26248382

  5. Pyrazoles as promising scaffold for the synthesis of anti-inflammatory and/or antimicrobial agent: a review.

    PubMed

    Bekhit, Adnan A; Hymete, Ariaya; El-Din A Bekhit, Alaa; Damtew, Ashenafi; Aboul-Enein, Hassan Y

    2010-10-01

    There has been a considerable interest in the development of novel compounds with anti-inflammatory and /or antimicrobial activities. Several economical and social merits have been prospected for compounds with dual effects. Pyrazoles are an important class of compounds for new drug development that attracted much attention. Several pyrazole derivatives have been synthesized as target structures and evaluated for their biological activities. This review describes the synthesis and the development of new pyrazoles that possess anti-inflammatory and /or antimicrobial activities. The cytotoxicity of the reported compounds indicate good safety associated with many of the pyrazole derivatives, however, the need for standardized method for cytotoxicity evaluation is required for better understanding of the compounds safety and the safety-structure relationships. PMID:20540709

  6. In vitro susceptibility to antimicrobial agents and ultrastructural characteristics related to swimming motility and drug action in Campylobacter jejuni and C. coli.

    PubMed

    Yabe, Shizuka; Higuchi, Wataru; Takano, Tomomi; Razvina, Olga; Iwao, Yasuhisa; Isobe, Hirokazu; Yamamoto, Tatsuo

    2010-06-01

    Campylobacter jejuni has recently been noted as the most common cause of bacterial food-borne diseases in Japan. In this study, we examined in vitro susceptibility to 36 antimicrobial agents of 109 strains of C. jejuni and C. coli isolated from chickens and patients with enteritis or Guillain-Barré syndrome from 1996 to 2009. Among these agents, carbapenems (imipenem, meropenem, panipenem, and biapenem) showed the greatest activity [minimal inhibitory concentration (MIC)(90), 0.03-0.125 microg/ml]. This was followed by sitafloxacin (MIC(90), 0.25 microg/ml), furazolidone and azithromycin (MIC(90), 0.5 microg/ml), gentamicin and clindamycin (MIC(90), 1 microg/ml), and clavulanic acid (beta-lactamase inhibitor; MIC(90), 2 microg/ml). All or most strains were resistant to aztreonam, sulfamethoxazole, and trimethoprim. Marked resistance was also observed for levofloxacin and tetracyclines. Resistance was not present for macrolides and rare for clindamycin. C. jejuni (and C. coli) exhibited high swimming motility and possessed a unique end-side (cup-like) structure at both ends, in contrast to Helicobacter pylori and Vibrio cholerae O1 and O139. The morphology of C. jejuni (and C. coli) changed drastically after exposure to imipenem (coccoid formation), meropenem (bulking and slight elongation), and sitafloxacin (marked elongation), and exhibited reduced motility. In the HEp-2 cell adherence model, unusually elongated bacteria were also observed for sitafloxacin. The data suggest that although resistance to antimicrobial agents (e.g., levofloxacin) has continuously been noted, carbapenems, sitafloxacin, and others such as beta-lactamase inhibitors alone showed good in vitro activity and that C. jejuni (and C. coli) demonstrated a unique ultrastructural nature related to high swimming motility and drug action. PMID:20225076

  7. Efficacies of various antimicrobial agents in treatment of Staphylococcus aureus abscesses and correlation with in vitro tests of antimicrobial activity and neutrophil killing.

    PubMed Central

    Bamberger, D M; Fields, M T; Herndon, B L

    1991-01-01

    A rabbit perforated-capsule model was utilized to study antimicrobial efficacy in treating 2-week-old Staphylococcus aureus abscesses. Animals received either ciprofloxacin (30 mg/kg), cefazolin (100 mg/kg), or ciprofloxacin (30 mg/kg) plus rifampin (20 mg/kg) every 8 h for 8 days or no antibiotic. Antibiotic levels within the abscess exceeded the MIC for the test organism. At the end of treatment, ciprofloxacin was no more effective than the control, animals receiving cefazolin had a mean log10 fall of 2.41 CFU/ml, and animals receiving ciprofloxacin plus rifampin had a mean log10 reduction of 5.06 CFU/ml (P = less than 0.01). Six days after completion of therapy, all abscesses in animals receiving ciprofloxacin plus rifampin were culture negative. Surviving organisms in animals receiving ciprofloxacin or rifampin did not develop resistance to the treatment antibiotics. In vitro time-kill curves performed with logarithmic- and stationary-phase organisms in broth, serum, and abscess fluid supernatants did not correlate with the in vivo results. Neutrophil killing studies of S. aureus pretreated with antibiotics revealed greater killing of organisms pretreated with ciprofloxacin plus rifampin than of those pretreated with cefazolin or ciprofloxacin alone. In conclusion, ciprofloxacin plus rifampin was effective therapy in this staphylococcal abscess model, compared with the moderate efficacy of cefazolin and no effect observed with ciprofloxacin alone. Enhanced neutrophil killing of S. aureus pretreated with antibiotics may be an important mechanism by which bacteria are killed in suppurative infections. PMID:1804006

  8. Impact of transgenic Bt maize residues on the mycotoxigenic plant pathogen Fusarium graminearum and the biocontrol agent Trichoderma atroviride.

    PubMed

    Naef, Andreas; Zesiger, Thierry; Défago, Geneviève

    2006-01-01

    Transformation of maize with genes encoding for insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) could have an impact on the saprophytic survival of plant pathogens and their antagonists on crop residues. We assessed potential effects on the mycotoxin deoxynivalenol (DON)-producing wheat and maize pathogen Fusarium graminearum and on the biocontrol agent Trichoderma atroviride. Purified Cry1Ab protein caused no growth inhibition of these fungi on agar plates. Cry1Ab concentrations above levels common in Bt maize tissue stimulated the growth of F. graminearum. The fungi were also grown on gamma-radiation-sterilized leaf tissue of four Bt maize hybrids and their non transgenic isolines collected at maize maturity on a field trial in 2002 and 2003. Both fungi degraded the Cry1Ab protein in Bt maize tissue. Fungal biomass quantification with microsatellite-based polymerase chain reaction (PCR) assays revealed differential fungal growth on leaf tissue of different maize varieties but no consistent difference between corresponding Bt and non-Bt hybrids. Generally, year of maize tissue collection had a greater impact on biomass production than cultivar or Bt transformation. The mycotoxin DON levels observed in maize tissue experiments corresponded with patterns in F. graminearum biomass, indicating that Bt transformation has no impact on DON production. In addition to bioassays, maize leaf tissue was analyzed with a mass spectrometer-based electronic nose, generating fingerprints of volatile organic compounds. Chemical fingerprints of corresponding Bt and non-Bt leaf tissues differed only for those hybrid pairs that caused differential fungal biomass production in the bioassays. Our results suggest that Cry1Ab protein in maize residues has no direct effect on F. graminearum and T. atroviride but some corresponding Bt/non-Bt maize hybrids differ more in composition than Cry protein content alone, which can affect the saprophytic growth of fungi on crop

  9. Binary and Tertiary Mixtures of Satureja hortensis and Origanum vulgare Essential Oils as Potent Antimicrobial Agents Against Helicobacter pylori.

    PubMed

    Lesjak, Marija; Simin, Natasa; Orcic, Dejan; Franciskovic, Marina; Knezevic, Petar; Beara, Ivana; Aleksic, Verica; Svircev, Emilija; Buzas, Krisztina; Mimica-Dukic, Neda

    2016-03-01

    Essential oils possess strong antimicrobial activity, even against multiresistant Helicobacter pylori. Available therapies against H. pylori infection have multiple disadvantages, indicating a great need for a development of new therapeutics. The purpose of this study was to develop a potent natural product based anti-H. pylori formulation. First, anti-H. pylori activity of nine essential oils was determined, after which the most active oils were mixed in various ratios for further testing. Satureja hortensis, Origanum vulgare subsp. vulgare and O. vulgare subsp. hirtum essential oils expressed the highest activity (MIC = 2 μL mL(-1)). Their binary and ternary mixtures exhibited notably higher antimicrobial activity (MIC ≤ 2 μL mL(-1)). The most active was the mixture of S. hortensis and O. vulgare subsp. hirtum oils in volume ratio 2:1, which expressed 4 times higher activity than individual oils (MIC = 0.5 μL mL(-1)). According to GC-MS, both oils in the mixture were characterized by high content of phenols (48-73%), with carvacrol as the main carrier of antimicrobial activity. Presented in vitro study pointed out binary mixture of S. hortensis and O. vulgare subsp. hirtum essential oils in volume ratio 2:1 as promising candidate for further in vivo studies targeting H. pylori infection. PMID:26686190

  10. In Vitro Analysis of Activities of 16 Antimicrobial Agents against Gram-Negative Bacteria from Six Teaching Hospitals in China.

    PubMed

    Chen, Hongbin; Wang, Zhanwei; Li, Henan; Wang, Qi; Zhao, Chunjiang; He, Wenqiang; Wang, Xiaojuan; Zhang, Feifei; Wang, Hui

    2015-01-01

    To evaluate the in vitro antimicrobial activities of biapenem, arbekacin, and cefminox against different gram-negative bacterial isolates in China, a total of 100 non-duplicated Escherichia coli, 100 Acinetobacter baumannii, 100 Pseudomonas aeruginosa, and 99 Klebsiella pneumoniae isolates were collected from 6 teaching hospitals in China in 2012. The minimal inhibitory concentrations (MICs) of biapenem, arbekacin, cefminox and 13 other antibiotics were determined by the broth microdilution method. The carbapenems (biapenem, meropenem, and imipenem) exhibited high antimicrobial activity against E. coli (98%) and K. pneumoniae (≥95%), followed by colistin and amikacin. The MIC50 and MIC90 of biapenem against E. coli were ≤0.06 mg/L and 0.25 mg/L, respectively. For K. pneumoniae, the MIC50 and MIC90 of biapenem were 0.25 mg/L and 1.0 mg/L, respectively. The MIC50 and MIC90 of cefminox against E. coli were 1.0 mg/L and 4.0 mg/L, respectively. The resistance rates of A. baumannii to most of the antibiotics were more than 50%, except for colistin. Amikacin was the most active antibiotic against P. aeruginosa (97%), followed by colistin (93%). The MIC50 and MIC90 of arbekacin against P. aeruginosa were 2.0 mg/L and 8.0 mg/L, respectively. In conclusion, carbapenems, colistin, amikacin, and arbekacin exhibited high antimicrobial activities against gram-negative bacteria, except A. baumannii. PMID:25672407

  11. Interaction and effectiveness of antimicrobials along with healing-promoting agents in a novel biocellulose wound dressing.

    PubMed

    Napavichayanun, Supamas; Amornsudthiwat, Phakdee; Pienpinijtham, Prompong; Aramwit, Pornanong

    2015-10-01

    An ideal wound dressing should keep the wound moist, allow oxygen permeation, adsorb wound exudate, accelerate re-epithelialization for wound closure, reduce pain and healing time, and prevent infection. Our novel biocellulose-based wound dressing was composed of three components: 1) biocellulose (BC), intended to create a moist and oxygen-permeated environment with exudate adsorption; 2) silk sericin (SS) known for its enhancement of collagen type I production, which is critical for re-epithelialization; and 3) the antiseptic polyhexamethylene biguanide (PHMB). To deliver an effective BC wound dressing, the interactions between the components (PHMB vs. SS) needed to be thoroughly analyzed. In this study, we investigated important parameters such as the loading sequence, loading concentration, and loading amount of the active compounds to ensure that the BC wound dressing could provide both antimicrobial activity and promote collagen production during healing. The loading sequence of SS and PHMB into BC was critical to maintain PHMB antimicrobial activity; silk sericin needed to be loaded before PHMB to avoid any negative impacts. The minimum PHMB concentration was 0.3% w/v for effective elimination of all tested bacteria (Bacillus subtilis, Staphylococcus aureus, methicillin-resistant S. aureus, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa). The amounts of SS and PHMB in BC were optimized to ensure that the dressings released the optimal amounts of both SS to enhance fibroblast collagen production and PHMB for effective antimicrobial activity. PMID:26117743

  12. Comparative study of different chromatographic techniques for the analysis of multi-residues of some approved antimicrobials in fish tissues.

    PubMed

    Riad, Safa'a M; Rezk, Mamdouh R; Khattab, Fatma I; Marzouk, Hoda M

    2015-01-01

    Two chromatographic methods were developed, optimized and validated for the simultaneous determination of three approved aquaculture antimicrobials, namely sulphadimethoxine sodium, trimethoprim and florphenicol in fish tissues. The developed methods were based on simple liquid extraction technique. The first method employs thin-layer chromatography as a clean-up procedure coupled with densitometric determination for the separated drugs. The second method is an HPLC one using X-Terra™ C18 column. Several mobile-phase systems and extracting solvents were tried to optimize the separation and the extraction procedures from fish tissues. The procedures were applied for the analysis of spiked fish tissue samples at three different concentration levels (10, 50 and 100 ppm). A comparative study was conducted between the proposed methods to discuss the advantage of each one. The methods were validated according to the international conference on harmonization guidelines. The proposed methods were successfully applied for the determination of the studied drugs in spiked fish tissues, pure powders and in their veterinary pharmaceutical formulation. PMID:26184768

  13. [Comparison of antimicrobial use density (AUD) of carbapenem antibacterial agents and investigation of the drug susceptibility of Pseudomonas aeruginosa in 3 hospitals in southern Ibaraki Prefecture, Japan].

    PubMed

    Oishi, Tsuyoshi; Hitomi, Shigemi; Kamoshita, Masaharu; Fukue, Hidetaka; Kawahata, Daisuke; Fukutake, Katsuyuki

    2008-07-01

    The optimal use of anti-Pseudomonas agents is an important issue in the prevention of a tolerance against Pseudomonas aeruginosa. We evaluated the effect of antimicrobial use density (AUD) of carbapenem on drug susceptibility. The AUD of the four carbapenems, imipenem (IPM/CS), panipenem (PAPM/BP), meropenem (MEPM), and biapenem (BIPM), was examined at three hospitals in Ibaraki Prefecture, between April and September 2004. The AUD was calculated using the Defined Daily Doses (DDD) methodology developed by the WHO. A drug susceptibility test was conducted on the 306 Pseudomonas aeruginosa strains randomly collected from clinical specimens at the three hospitals between September and December 2004. In accordance with the standards set by the Clinical and Laboratory Standards Institute (CLSI), minimal inhibitory concentration (MIC) was measured using the broth microdilution method. The results showed that the AUD of carbapenem at the three hospitals tended to be higher than that in other research results in Japan. At one of the three hospitals, the AUD of the PAPM was remarkably high compared to the other carbapenems. Furthermore, P. aeruginosa strains collected at this hospital showed a low susceptibility to carbapenem, and many highly tolerant strains were also observed in this hospital. In order to maintain the susceptibility of Pseudomonas aeruginosa to carbapenem, the overall extent of carbapenem use must be optimal. The use of antimicrobial drugs should be controlled properly at each hospital, in order to prevent excessive use of PAPM/BP from being used over a long period of time. PMID:18709988

  14. In Vitro Approach for Identification of the Most Effective Agents for Antimicrobial Lock Therapy in the Treatment of Intravascular Catheter-Related Infections Caused by Staphylococcus aureus.

    PubMed

    Hogan, S; Zapotoczna, M; Stevens, N T; Humphreys, H; O'Gara, J P; O'Neill, E

    2016-05-01

    Infection of intravascular catheters by Staphylococcus aureus is a significant risk factor within the health care setting. To treat these infections and attempt salvage of an intravascular catheter, antimicrobial lock solutions (ALSs) are being increasingly used. However, the most effective ALSs against these biofilm-mediated infections have yet to be determined, and clinical practice varies greatly. The purpose of this study was to evaluate and compare the efficacies of antibiotics and antiseptics in current clinical use against biofilms produced by reference and clinical isolates of S. aureus Static and flow biofilm assays were developed using newly described in vivo-relevant conditions to examine the effect of each agent on S. aureus within the biofilm matrix. The antibiotics daptomycin, tigecycline, and rifampin and the antiseptics ethanol and Taurolock inactivated established S. aureus biofilms, while other commonly used antistaphylococcal antibiotics and antiseptic agents were less effective. These findings were confirmed by live/dead staining of S. aureus biofilms formed and treated within a flow cell model. The results from this study demonstrate the most effective clinically used agents and their concentrations which should be used within an ALS to treat S. aureus-mediated intravascular catheter-related infections. PMID:26926633

  15. 1,5-Benzodiazepine derivatives as potential antimicrobial agents: design, synthesis, biological evaluation, and structure-activity relationships.

    PubMed

    Wang, Lan-Zhi; Li, Xiao-Qing; An, Ying-Shuang

    2015-05-21

    36 Novel 1,5-benzodiazepine derivatives were rationally designed and synthesized according to the principle of superposition of bioactive substructures by the combination of 1,5-benzodiazepines, thiophene or thiazole and ester group. The structures of the target compounds have been characterized by IR, (1)H NMR, (13)C NMR, MS and elemental analysis. The structure of 1v was further determined using X-ray single crystal diffraction. All synthesized 1,5-benzodiazepine derivatives were evaluated for their in vitro antimicrobial activity against C. neoformans, C. neoformans clinical isolates, C. albicans, E. coli and S. aureus. The bioactive assay results revealed that most of the 1,5-benzodiazepine derivatives exhibited considerable potency against all of the tested strains. In particular, compounds 1v and 1w (MIC: 2-6 μg mL(-1), MFC: 10-14 μg mL(-1)) exhibited excellent antifungal activity and were found to be 32-64 and 9-12.8 times more potent than the reference drugs against C. neoformans, respectively. Moreover, compound (MIC: 40 μg mL(-1)) displayed equipotent antibacterial activity against E. coli and S. aureus compared to the reference drugs. The most potent of the synthesized compounds 1v and 1w were further studied by evaluating their cytotoxicities, and the results showed that they had relatively low level cytotoxicity for BV2 cell. A preliminary study of the structure-activity relationship revealed that substituents in the phenyl ring and the thiophene ring had a great effect on the antimicrobial activity of these compounds. In addition, the thiazole ring at C2 may be a pharmacophore of these compounds and COOC2H5 group at C3 is the best substituent for the maintenance of antimicrobial activities at low concentrations (1.5625 μg per disc). PMID:25875695

  16. Synthesis, characterization and biological evaluation of some novel 2,4-thiazolidinediones as potential cytotoxic, antimicrobial and antihyperglycemic agents.

    PubMed

    Avupati, Vasudeva Rao; Yejella, Rajendra Prasad; Akula, Annapurna; Guntuku, Girija Sankar; Doddi, Bhagya Raju; Vutla, Venkata Rao; Anagani, Suvarna Ratna; Adimulam, Lakshmana Santhi; Vyricharla, Aruna Kumar

    2012-10-15

    A series of some novel 2,4-thiazolidinediones (TZDs) (2a-x) have been synthesized and characterized by FTIR, (1)H NMR, (13)C NMR and LC mass spectral analysis. All the synthesized compounds were evaluated for their cytotoxicity, antimicrobial and in vivo antihyperglycemic activities. Among the tested compounds for cytotoxicity using Brine Shrimp Lethality assay, compound 2t ((Z)-5-(4-((E)-3-oxo-3-(thiophen-2-yl)prop-1-enyl)benzylidene)-1,3-thiazolidine-2,4-dione) exhibited significant inhibitory activity at ED(50) value 4.00±0.25 μg/mL and this level of activity was comparable to that of the reference drug podophyllotoxin with ED(50) value 3.61±0.17 μg/mL. Antimicrobial activity was screened using agar well diffusion assay method against selected Gram-positive, Gram-negative and fungal strains and the activity expressed as the minimum inhibitory concentration (MIC) in μg/mL. From the results of antimicrobial activity compound 2s ((Z)-5-(4-((E)-3-(3,5-bis(benzyloxy)phenyl)-3-oxoprop-1-enyl)benzylidene)-1,3-thiazolidine-2,4-dione) was found to be the most active against all the tested strains of microorganisms with MIC value 16 μg/mL. In vivo antihyperglycemic effect of twenty four TZDs (2a-x) at different doses 10, 30 and 50mg/kg b.w (oral) were assessed using percentage reduction of plasma glucose (PG) levels in streptozotocin-induced type II diabetic rat models. From the results, the novel compound 2x ((Z)-5-(4-((E)-3-(9H-fluoren-2-yl)-3-oxoprop-1-enyl)benzylidene)-1,3-thiazolidine-2,4-dione) exhibited considerably potent blood glucose lowering activity than that of the standard drug rosiglitazone and it could be a remarkable starting point to evaluate structure-activity relationships and to develop new lead molecules with potential cytotoxicity, antimicrobial and antihyperglycemic activities. In addition molecular docking studies were carried out against PPARγ molecular target using Molegro Virtual Docker v 4.0 to accomplish preliminary confirmation of the

  17. Resistance to antimicrobial agents of Vibrio cholerae El Tor strains isolated during the fourth cholera epidemic in the United Republic of Tanzania

    PubMed Central

    Towner, K. J.; Pearson, N. J.; Mhalu, F. S.; O'Grady, F.

    1980-01-01

    Isolates of Vibrio cholerae obtained immediately after the outbreak of the fourth recorded epidemic of cholera in the United Republic of Tanzania were sensitive to tetracycline, but after five months of its extensive therapeutic and prophylactic use, 76% of the isolates were observed to be resistant to this and other antimicrobial agents. The appearance of resistance was found to be due to the rapid spread of antibiotic resistance plasmids belonging to the C incompatibility complex. Although most plasmid incompatibility groups have been shown to be unstable in V. cholerae, the strains found in the present epidemic seem to carry a plasmid belonging to one of the few relatively stable groups. These findings emphasize the importance of monitoring any emergence of bacterial resistance that may occur when mass prophylaxis programmes are in operation and also the importance of determining the genetic basis of the resistance mechanism. PMID:6975183

  18. First report on rapid screening of nanomaterial-based antimicrobial agents against β-lactamase resistance using pGLO plasmid transformed Escherichia coli HB 101 K-12

    NASA Astrophysics Data System (ADS)

    Raj, M. Alpha; Muralidhar, Y.; Sravanthi, M.; Prasad, T. N. V. K. V.; Nissipriya, M.; Reddy, P. Sirisha; Neelima, T. Shoba; Reddy, G. Dilip; Adilaxmamma, K.; Kumar, P. Anand; Krishna, T. Giridhara

    2016-08-01

    Combating antibiotic resistance requires discovery of novel antimicrobials effective against resistant bacteria. Herein, we present for the first time, pGLO plasmid transformed Escherichia coli HB 101 K 12 as novel model for screening of nanomaterial-based antimicrobial agents against β-lactamase resistance. E. coli HB 101 was transformed by pGLO plasmid in the presence of calcium chloride (50 mM; pH 6.1) aided by heat shock (0-42-0 °C). The transformed bacteria were grown on Luria-Bertani agar containing ampicillin (amp) and arabinose (ara). The transformed culture was able to grow in the presence of ampicillin and also exhibited fluorescence under UV light. Both untransformed and transformed bacteria were used for screening citrate-mediated nanosilver (CNS), aloin-mediated nanosilver (ANS), 11-α-keto-boswellic acid (AKBA)-mediated nanosilver (BNS); nanozinc oxide, nanomanganese oxide (NMO) and phytochemicals such as aloin and AKBA. Minimum inhibitory concentrations (MIC) were obtained by microplate method using ρ-iodo nitro tetrazolium indicator. All the compounds were effective against transformed bacteria except NMO and AKBA. Transformed bacteria exhibited reverse cross resistance against aloin. ANS showed the highest antibacterial activity with a MIC of 0.32 ppm followed by BNS (10.32 ppm), CNS (20.64 ppm) and NZO (34.83 ppm). Thus, pGLO plasmid can be used to induce resistance against β-lactam antibiotics and the model can be used for rapid screening of new antibacterial agents effective against resistant bacteria.

  19. First report on rapid screening of nanomaterial-based antimicrobial agents against β-lactamase resistance using pGLO plasmid transformed Escherichia coli HB 101 K-12

    NASA Astrophysics Data System (ADS)

    Raj, M. Alpha; Muralidhar, Y.; Sravanthi, M.; Prasad, T. N. V. K. V.; Nissipriya, M.; Reddy, P. Sirisha; Neelima, T. Shoba; Reddy, G. Dilip; Adilaxmamma, K.; Kumar, P. Anand; Krishna, T. Giridhara

    2015-10-01

    Combating antibiotic resistance requires discovery of novel antimicrobials effective against resistant bacteria. Herein, we present for the first time, pGLO plasmid transformed Escherichia coli HB 101 K 12 as novel model for screening of nanomaterial-based antimicrobial agents against β-lactamase resistance. E. coli HB 101 was transformed by pGLO plasmid in the presence of calcium chloride (50 mM; pH 6.1) aided by heat shock (0-42-0 °C). The transformed bacteria were grown on Luria-Bertani agar containing ampicillin (amp) and arabinose (ara). The transformed culture was able to grow in the presence of ampicillin and also exhibited fluorescence under UV light. Both untransformed and transformed bacteria were used for screening citrate-mediated nanosilver (CNS), aloin-mediated nanosilver (ANS), 11-α-keto-boswellic acid (AKBA)-mediated nanosilver (BNS); nanozinc oxide, nanomanganese oxide (NMO) and phytochemicals such as aloin and AKBA. Minimum inhibitory concentrations (MIC) were obtained by microplate method using ρ-iodo nitro tetrazolium indicator. All the compounds were effective against transformed bacteria except NMO and AKBA. Transformed bacteria exhibited reverse cross resistance against aloin. ANS showed the highest antibacterial activity with a MIC of 0.32 ppm followed by BNS (10.32 ppm), CNS (20.64 ppm) and NZO (34.83 ppm). Thus, pGLO plasmid can be used to induce resistance against β-lactam antibiotics and the model can be used for rapid screening of new antibacterial agents effective against resistant bacteria.

  20. Antimicrobial evaluation of new metallic complexes with xylitol active against P. aeruginosa and C. albicans: MIC determination, post-agent effect and Zn-uptake.

    PubMed

    Santi, E; Facchin, G; Faccio, R; Barroso, R P; Costa-Filho, A J; Borthagaray, G; Torre, M H

    2016-02-01

    Xylitol (xylH5) is metabolized via the pentose pathway in humans, but it is unsuitable as an energy source for many microorganisms where it produces a xylitol-induced growth inhibition and disturbance in protein synthesis. For this reason, xylitol is used in the prophylaxis of several infections. In the search of better antimicrobial agents, new copper and zinc complexes with xylitol were synthesized and characterized by analytical and spectrosco pic methods: Na2[Cu3(xylH−4)2]·NaCl·4.5H2O (Cu-xyl) and [Zn4(xylH−4)2(H2O)2]·NaCl·3H2O (Zn-xyl). Both copper and zinc complexes presented higher MIC against Pseudomona aeruginosa than the free xylitol while two different behaviors were found against Candida albicans depending on the complex. The growth curves showed that Cu-xyl presented lower activity than the free ligand during all the studied period. In the case of Znxyl the growth curves showed that the inhibition of the microorganism growth in the first stage was equivalent to that of xylitol but in the second stage (after 18 h) Zn-xyl inhibited more. Besides, the PAE (post agent effect)obtained for Zn-xyl and xyl showed that the recovery from the damage of microbial cells had a delay of 14 and 13 h respectively. This behavior could be useful in prophylaxis treatments for infectious diseases where it is important that the antimicrobial effect lasts longer. With the aim to understand the microbiological activities the analysis of the particle size, lipophilicity and Zn uptake was performed. PMID:26619097

  1. Antibiotic Conjugated Fluorescent Carbon Dots as a Theranostic Agent for Controlled Drug Release, Bioimaging, and Enhanced Antimicrobial Activity

    PubMed Central

    Patil, Vaibhav; Khade, Monika; Goshi, Ekta; Sharon, Madhuri

    2014-01-01

    A novel report on microwave assisted synthesis of bright carbon dots (C-dots) using gum arabic (GA) and its use as molecular vehicle to ferry ciprofloxacin hydrochloride, a broad spectrum antibiotic, is reported in the present work. Density gradient centrifugation (DGC) was used to separate different types of C-dots. After careful analysis of the fractions obtained after centrifugation, ciprofloxacin was attached to synthesize ciprofloxacin conjugated with C-dots (Cipro@C-dots conjugate). Release of ciprofloxacin was found to be extremely regulated under physiological conditions. Cipro@C-dots were found to be biocompatible on Vero cells as compared to free ciprofloxacin (1.2 mM) even at very high concentrations. Bare C-dots (∼13 mg mL−1) were used for microbial imaging of the simplest eukaryotic model—Saccharomyces cerevisiae (yeast). Bright green fluorescent was obtained when live imaging was performed to view yeast cells under fluorescent microscope suggesting C-dots incorporation inside the cells. Cipro@C-dots conjugate also showed enhanced antimicrobial activity against both model gram positive and gram negative microorganisms. Thus, the Cipro@C-dots conjugate paves not only a way for bioimaging but also an efficient new nanocarrier for controlled drug release with high antimicrobial activity, thereby serving potential tool for theranostics. PMID:24744921

  2. Evaluation of antimicrobial peptide nisin as a safe vaginal contraceptive agent in rabbits: in vitro and in vivo studies.

    PubMed

    Reddy, K V R; Aranha, C; Gupta, S M; Yedery, R D

    2004-07-01

    In the midst of the global epidemics of both unwanted pregnancies and sexually transmitted infections (STIs), options that provide protection are ideal. In the present study, nisin, a known antimicrobial peptide, was evaluated for safety and contraceptive potential in vitro and in vivo in the rabbit. A concentration of 400 microg nisin per ml was found to be spermicidal in vitro, and the effect was dose and time dependent. In vivo studies indicated that intravaginal application of 1 mg nisin blocked conception in rabbits. Repeated application of nisin (50 mg/animal per day) in rabbits for 14 consecutive days did not cause local inflammation or damage to the vaginal epithelium. In addition, the rate of diffusion of nisin into the blood via the vaginal mucosal epithelium, and its clearance from the circulation was found to be rapid. No treatment-related changes were observed in the reproductive performance of rabbits after cessation of treatment. Furthermore, no changes were observed in the gestation period, subsequent growth and survival of neonates in these animals. When male rats were given nisin orally for 13 consecutive weeks, no effect was observed on reproductive performance. The number of pups born, survival and growth of pups were unaltered. The affinity studies of nisin revealed that spermatozoa are more susceptible to nisin than red blood cells and vaginal epithelial cells. We suggest that nisin with spermicidal and antimicrobial properties could serve as a safe vaginal contraceptive for future therapeutic interventions in STIs. PMID:15232069

  3. Synthesis and Antibacterial Evaluation of New Thione Substituted 1,2,4-Triazole Schiff Bases as Novel Antimicrobial Agents

    PubMed Central

    Akbari Dilmaghani, Karim; Nasuhi Pur, Fazel; Hatami Nezhad, Mahnaz

    2015-01-01

    The condensation reaction of 5-(4-aminophenyl)-4-phenyl-1,2,4-triazole-3-thione with salicylaldehyde, 4-hydroxybenzaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 2-nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde and 4-methoxybenzaldehyde in methanol results in series of new Schiff bases. The structure of Schiff bases were confirmed by 1H NMR, 13C NMR, IR and mass spectroscopy. The synthesized compounds were tested for their antimicrobial activity against bacterial (Gram negative and Gram positive) strains in-vitro. The synthetic compounds showed different inhibition zones against tested bacterial strains. All compounds showed significant antiproliferative activity against Acinetobacter calcoaceticus ATCC 23055. In detail, Entrococcus faecalis (Gram positive) was resistant to all prepared compounds, whereas, A. calcoaceticus (Gram negative) was sensitive to all compounds especially 5c, 5d and 4. S. aureus (Gram positive, relatively resistant to antimicrobials) showed limited sensitivity to only 5c and 5d, and it was resistant to all other compounds and only 5c exhibited low activity against P. aeruginosa (Gram negative). The best results belonged to 5c that showed high activity against A. calcoaceticus (33 mm) as well as S. aureus (20 mm). PMID:26330857

  4. From individual to collective immunity: the role of the venom as antimicrobial agent in the Stenogastrinae wasp societies.

    PubMed

    Baracchi, David; Mazza, Giuseppe; Turillazzi, Stefano

    2012-01-01

    Sociality is associated with an increased risk of disease transmission and one of the first defense of the insect colonies is represented by antimicrobial secretions. In many eusocial hymenopteran species venom glands represent one of the most important source of antimicrobial substances. It is known that in highly eusocial species the venom is spread on both the cuticle of insects and the comb, thus becoming a component of the so called "social immunity". So far, it is never been ascertained whether this phenomenon is also present in more primitively eusocial and incipiently eusocial groups. Using incipiently eusocial hover wasps as model, we demonstrate that venom is present on insect cuticles and that it strongly acts against microorganisms. By contrast, the nest, regardless of materials, does not represent a ''medium" where the venom is deposited by wasps in order to act as a social antiseptic weapon. Our findings discussed in an evolutionary perspective indicate that a certain degree of sociality or a sufficient number of individuals in an insect society are thresholds to be reached for the rise of complex and efficient forms of collective and social immunity as mechanisms of resistance to diseases. PMID:22108024

  5. Exploring the use of natural antimicrobial agents and pulsed electric fields to control spoilage bacteria during a beer production process.

    PubMed

    Galvagno, M A; Gil, G R; Iannone, L J; Cerrutti, P

    2007-01-01

    Different natural antimicrobials affected viability of bacterial contaminants isolated at critical steps during a beer production process. In the presence of 1 mg/ml chitosan and 0.3 mg/ml hops, the viability of Escherichia coli in an all malt barley extract wort could be reduced to 0.7 and 0.1% respectively after 2 hour- incubation at 4 degrees C. The addition of 0.0002 mg/ml nisin, 0.1 mg/ml chitosan or 0.3 mg/ml hops, selectively inhibited growth of Pediococcus sp. in more than 10,000 times with respect to brewing yeast in a mixed culture. In the presence of 0.1 mg ml chitosan in beer, no viable cells of the thermoresistant strain Bacillus megaterium were detected. Nisin, chitosan and hops increased microbiological stability during storage of a local commercial beer inoculated with Lactobacillus plantarum or Pediococcus sp. isolated from wort. Pulsed Electric Field (PEF) (8 kV/cm, 3 pulses) application enhanced antibacterial activity of nisin and hops but not that of chitosan. The results herein obtained suggest that the use of these antimicrobial compounds in isolation or in combination with PEF would be effective to control bacterial contamination during beer production and storage. PMID:17987854

  6. Synthesis and Antibacterial Evaluation of New Thione Substituted 1,2,4-Triazole Schiff Bases as Novel Antimicrobial Agents.

    PubMed

    Akbari Dilmaghani, Karim; Nasuhi Pur, Fazel; Hatami Nezhad, Mahnaz

    2015-01-01

    The condensation reaction of 5-(4-aminophenyl)-4-phenyl-1,2,4-triazole-3-thione with salicylaldehyde, 4-hydroxybenzaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 2-nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde and 4-methoxybenzaldehyde in methanol results in series of new Schiff bases. The structure of Schiff bases were confirmed by (1)H NMR, (13)C NMR, IR and mass spectroscopy. The synthesized compounds were tested for their antimicrobial activity against bacterial (Gram negative and Gram positive) strains in-vitro. The synthetic compounds showed different inhibition zones against tested bacterial strains. All compounds showed significant antiproliferative activity against Acinetobacter calcoaceticus ATCC 23055. In detail, Entrococcus faecalis (Gram positive) was resistant to all prepared compounds, whereas, A. calcoaceticus (Gram negative) was sensitive to all compounds especially 5c, 5d and 4. S. aureus (Gram positive, relatively resistant to antimicrobials) showed limited sensitivity to only 5c and 5d, and it was resistant to all other compounds and only 5c exhibited low activity against P. aeruginosa (Gram negative). The best results belonged to 5c that showed high activity against A. calcoaceticus (33 mm) as well as S. aureus (20 mm). PMID:26330857

  7. Saturation mutagenesis of selected residues of the α-peptide of the lantibiotic lacticin 3147 yields a derivative with enhanced antimicrobial activity

    PubMed Central

    Field, Des; Molloy, Evelyn M; Iancu, Catalin; Draper, Lorraine A; O' Connor, Paula M; Cotter, Paul D; Hill, Colin; Ross, R Paul

    2013-01-01

    Summary The lantibiotic lacticin 3147 consists of two ribosomally synthesized and post-translationally modified antimicrobial peptides, Ltnα and Ltnβ, which act synergistically against a wide range of Gram-positive microorganisms. We performed saturation mutagenesis of specific residues of Ltnα to determine their functional importance. The results establish that Ltnα is more tolerant to change than previously suggested by alanine scanning mutagenesis. One substitution, LtnαH23S, was identified which improved the specific activity of lacticin 3147 against one pathogenic strain, Staphylococcus aureus NCDO1499. This represents the first occasion upon which the activity of a two peptide lantibiotic has been enhanced through bioengineering. Funding Information Work in the authors' laboratory is supported by the Irish Government under the National Development Plan; by the Irish Research Council for Science Engineering and Technology (IRCSET); by Enterprise Ireland; and by Science Foundation Ireland (SFI), through the Alimentary Pharmabiotic Centre (APC) at University College Cork, Ireland, which is supported by the SFI-funded Centre for Science, Engineering and Technology (SFI-CSET) and provided P.D.C., C.H and R.P.R. with SFI Principal Investigator funding. PMID:23433070

  8. N-Succinimidyl guanidinomethyl iodobenzoate protein radiohalogenation agents: Influence of isomeric substitution on radiolabeling and target cell residualization

    PubMed Central

    Choi, Jaeyeon; Vaidyanathan, Ganesan; Koumarianou, Eftychia; McDougald, Darryl; Pruszynski, Marek; Osada, Takuya; Lahoutte, Tony; Lyerly, H. Kim; Zalutsky, Michael R.

    2014-01-01

    Introduction N-succinimidyl 4-guanidinomethyl-3-[*I]iodobenzoate ([*I]SGMIB) has shown promise for the radioiodination of monoclonal antibodies (mAbs) and other proteins that undergo extensive internalization after receptor binding, enhancing tumor targeting compared to direct electrophilic radioiodination. However, radiochemical yields for [131I]SGMIB synthesis are low, which we hypothesize is due to steric hindrance from the Boc-protected guanidinomethyl group ortho to the tin moiety. To overcome this, we developed the isomeric compound, N-succinimidyl 3-guanidinomethyl-5-[131I]iodobenzoate (iso-[131I]SGMIB) wherein this bulky group was moved from ortho to meta position. Methods Boc2-iso-SGMIB standard and its tin precursor, N-succinimidyl 3-((1,2-bis(tert-butoxycarbonyl)guanidino)methyl)-5-(trimethylstannyl)benzoate (Boc2-iso-SGMTB), were synthesized using two disparate routes, and iso-[*I]SGMIB synthesized from the tin precursor. Two HER2-targeted vectors — trastuzumab (Tras) and a nanobody 5F7 (Nb) — were labeled using iso-[*I]SGMIB and [*I]SGMIB. Paired-label internalization assays in vitro with both proteins, and biodistribution in vivo with trastuzumab, labeled using the two isomeric prosthetic agents were performed. Results When the reactions were performed under identical conditions, radioiodination yields for the synthesis of Boc2-iso-[131I]SGMIB were significantly higher than those for Boc2-[131I]SGMIB (70.7 ± 2.0% vs 56.5 ± 5.5%). With both Nb and trastuzumab, conjugation efficiency also was higher with iso-[131I]SGMIB than with [131I]SGMIB (Nb, 33.1 ± 7.1% vs 28.9 ± 13.0%; Tras, 45.1 ± 4.5% vs 34.8 ± 10.3%); however, the differences were not statistically significant. Internalization assays performed on BT474 cells with 5F7 Nb indicated similar residualizing capacity over 6 h; however, at 24 h, radioactivity retained intracellularly for iso-[131I]SGMIB-Nb was lower than for [125I]SGMIB-Nb (46.4 ± 1.3% vs 56.5 ± 2.5%); similar results were

  9. Frequency of resistance to methicillin and other antimicrobial agents among Staphylococcus aureus strains isolated from pigs and their human handlers in Trinidad

    PubMed Central

    Gordon, Annika; Marshall, Jennelle; Ramdass, Kris; Stewart-Johnson, Alva; Adesiyun, Abiodun

    2014-01-01

    Background Methicillin-resistant Staphylococcus aureus (MRSA) has emerged recently worldwide in production animals, particularly pigs and veal calves, which act as reservoirs for MRSA strains for human infection. The study determined the prevalence of MRSA and other resistant strains of S. aureus isolated from the anterior nares of pigs and human handlers on pig farms in Trinidad. Methods Isolation of S. aureus was done by concurrently inoculating Baird-Parker agar (BPA) and Chromagar MRSA (CHROM) with swab samples and isolates were identified using standard methods. Suspect MRSA isolates from Chromagar and BPA were subjected to confirmatory test using Oxoid PBP2 latex agglutination test. The disc diffusion method was used to determine resistance to antimicrobial agents. Results The frequency of isolation of MRSA was 2.1% (15 of 723) for pigs but 0.0% (0 of 72) for humans. Generally, for isolates of S. aureus from humans there was a high frequency of resistance compared with those from pigs, which had moderate resistance to the following antimicrobials: penicillin G (54.5%, 51.5%), ampicillin (59.1%, 49.5%), and streptomycin (59.1%, 37.1%), respectively. There was moderate resistance to tetracycline (36.4%, 41.2%) and gentamycin (27.2%, 23.7%) for human and pig S. aureus isolates, respectively, and low resistance to sulfamethoxazole-trimethoprim (4.5%, 6.2%) and norfloxacin (9.1%, 12.4%), respectively. The frequency of resistance to oxacillin by the disc method was 36.4 and 34.0% from S. aureus isolates from humans and pigs, respectively. Out of a total of 78 isolates of S. aureus from both human and pig sources that were resistant to oxacillin by the disc diffusion method, only 15 (19.2%) were confirmed as MRSA by the PBP'2 latex test kit. Conclusions The detection of MRSA strains in pigs, albeit at a low frequency, coupled with a high frequency of resistance to commonly used antimicrobial agents in pig and humans could have zoonotic and therapeutic implications

  10. Design and characterization of short antimicrobial peptides using leucine zipper templates with selectivity towards microorganisms.

    PubMed

    Ahmad, Aqeel; Azmi, Sarfuddin; Srivastava, Saurabh; Kumar, Amit; Tripathi, Jitendra Kumar; Mishra, Nripendra N; Shukla, Praveen K; Ghosh, Jimut Kanti

    2014-11-01

    Design of antimicrobial peptides with selective activity towards microorganisms is an important step towards the development of new antimicrobial agents. Leucine zipper sequence has been implicated in cytotoxic activity of naturally occurring antimicrobial peptides; moreover, this motif has been utilized for the design of novel antimicrobial peptides with modulated cytotoxicity. To understand further the impact of substitution of amino acids at 'a' and/or 'd' position of a leucine zipper sequence of an antimicrobial peptides on its antimicrobial and cytotoxic properties four short peptides (14-residue) were designed on the basis of a leucine zipper sequence without or with replacement of leucine residues in its 'a' and 'd' positions with D-leucine or alanine or proline residue. The original short leucine zipper peptide (SLZP) and its D-leucine substituted analog, DLSA showed comparable activity against the tested Gram-positive and negative bacteria and the fungal strains. The alanine substituted analog (ASA) though showed appreciable activity against the tested bacteria, it showed to some extent lower activity against the tested fungi. However, the proline substituted analog (PSA) showed lower activity against the tested bacterial or fungal strains. Interestingly, DLSA, ASA and PSA showed significantly lower cytotoxicity than SLZP against both human red blood cells (hRBCs) and murine 3T3 cells. Cytotoxic and bactericidal properties of these peptides matched with peptide-induced damage/permeabilization of mammalian cells and bacteria or their mimetic lipid vesicles suggesting cell membrane could be the target of these peptides. As evidenced by tryptophan fluorescence and acrylamide quenching studies the peptides showed similarities either in interaction or in their localization within the bacterial membrane mimetic negatively charged lipid vesicles. Only SLZP showed localization inside the mammalian membrane mimetic zwitterionic lipid vesicles. The results show

  11. Contrasting effects of two antimicrobial agents (triclosan and triclocarban) on biomineralisation of an organophosphate pesticide in soils.

    PubMed

    Kookana, R S; Ali, A; Smith, L; Arshad, M

    2014-07-01

    We examined the impact of triclosan (TCS) and triclocarban (TCC) antimicrobial compounds on the biomineralisation of glucose and cadusafos pesticide in three Australian soils. Mineralisations of radiolabelled ((14)C) compounds were measured over a period of up to 77 d in sterile and non-sterile soils treated with different concentrations of TCS and TCC (0-450 mg kg(-1)). The rates of mineralisation of cadusafos were found to decrease with increasing concentration of TCS in all soils, but varied with soil type. Soils treated with TCS at the highest concentration (270 mg kg(-1)) reduced cadusafos mineralisation by up to 58%. However, glucose mineralisation was not significantly affected by the presence of TCS. While TCS, significantly reduced the mineralisation of cadusafos (by 17%; p<0.05) even at the lowest studied concentration (30 mg kg(-1)), no significant effect of TCC was observed on cadusafos or glucose mineralisation even at the highest concentration used (450 mg kg(-1)). PMID:24461429

  12. Synthesis and Biological Evaluation of N- Pyrazolyl Derivatives and Pyrazolopyrimidine Bearing a Biologically Active Sulfonamide Moiety as Potential Antimicrobial Agent.

    PubMed

    Hafez, Hend N; El-Gazzar, Abdel-Rhman B A

    2016-01-01

    A series of novel pyrazole-5-carboxylate containing N-triazole derivatives 3,4; different heterocyclic amines 7a-b and 10a-b; pyrazolo[4,3-d]pyrimidine containing sulfa drugs 14a,b; and oxypyrazolo[4,3-d]pyrimidine derivatives 17, 19, 21 has been synthesized. The structure of the newly synthesized compounds was elucidated on the basis of analytical and spectral analyses. All compounds have been screened for their in vitro antimicrobial activity against three gram-positive and gram-negative bacteria as well as three fungi. The results revealed that compounds 14b and 17 had more potent antibacterial activity against all bacterial strains than reference drug Cefotaxime. Moreover compounds 4, 7b, and 12b showed excellent antifungal activities against Aspergillus niger and Candida albicans in low inhibitory concentrations but slightly less than the reference drug miconazole against Aspergillus flavus. PMID:27589717

  13. Silver Nanoparticles in SiO2 Microspheres - Preparation by Spray Drying and Use as Antimicrobial Agent.

    PubMed

    Mahltig, Boris; Haufe, Helfried; Muschter, Kerstin; Fischer, Anja; Kim, Young Hwan; Gutmann, Emanuel; Reibold, Marianne; Meyer, Dirk Carl; Textor, Torsten; Kim, Chang Woo; Kang, Young Soo

    2010-06-01

    Silver nanoparticles embedded in SiO2 particles of micrometer size are prepared using spray drying. The spray drying is performed with a SiO2 sol (solvent water:ethanol 4: 1) containing SiO2 and silver particles of nanometer size. During spray drying the SiO2 nanoparticles aggregate to SiO2 microspheres whereas the silver particles exhibit only a small tendency of aggregation and keep their nanometer size. However under special conditions also the formation of crystalline silver rods is observed. The antibacterial activity of the resulting Ag/SiO2 powders is determined against the bacteria Escherichia coli and Bacillus subtilis. Because of this antibacterial acitivity and the fact that the powder of SiO2 microspheres exhibits a good dispersibility, such materials have an immense potential to be used as antimicrobial additive in processes like master batch or fiber production. PMID:24061743

  14. Efficient Synthesis and Biological Evaluation of a Novel Series of 1,5-Benzodiazepine Derivatives as Potential Antimicrobial Agents.

    PubMed

    An, Ying-Shuang; Hao, Zhen-Fang; Zhang, Xiu-Jun; Wang, Lan-Zhi

    2016-07-01

    A series of novel 1,5-benzodiazepine derivatives were rationally designed and synthesized following the principle of the superposition of bioactive substructures by the combination of 1,5-benzodiazepine, pyridine (phenyl), and an ester group. The structures of the target compounds were determined by (1) H NMR, (13) C NMR, MS, IR, and elemental analysis. All the synthesized compounds were evaluated for their antimicrobial activities in vitro against the fungi C. neoformans, C. neoformans clinical isolates (ATCC 32264), C. albicans (ATCC 10231), Gram-negative bacterium E. coli (ATCC 44752), and Gram-positive bacterium S. aureus (ATCC 25923). The results of the bioactive assay demonstrated that most of the tested compounds exhibited variable inhibitory effects on the growth of the tested microorganisms. All the active compounds showed better antifungal activity than antibacterial activity. Notably, compound 2b displayed the highest activity (MIC = 30 μg/mL) against C. neoformans and (MIC = 31 μg/mL) against C. neoformans clinical isolates. In addition, compound 2a also showed excellent activity against C. neoformans and C. neoformans clinical isolates with minimum inhibitory concentration of 35 and 36 μg/mL, respectively. Compounds 2a and 2b were further studied by evaluating their cytotoxicities, and the results showed that they have relatively low level cytotoxicity for BV2 and 293T cell. Preliminary structure-activity relationship study on three diverse sets (C-2, C-3, and C-8 positions) of 1,5-benzodiazepines was performed. The results revealed that the presence of a -CH3 group at the C-8 position had a positive effect on the inhibitory activity of these compounds. Additionally, the 2-pyridyl group at the C-2 position may be a pharmacophore and -COOC2 H5 at C-3 position is the best substituent for the maintenance of antimicrobial activities. PMID:26850700

  15. Evaluation of minimum inhibitory and minimum bactericidal concentration of nano-silver base inorganic anti-microbial agent (Novaron®) against streptococcus mutans

    PubMed Central

    Holla, Goda; Yeluri, Ramakrishna; Munshi, Autar Krishen

    2012-01-01

    Objective: We attempted to find the possibility of determining the minimum inhibitory concentration and minimum bactericidal concentration needed for nano-silver base inorganic anti-microbial agent (Novaron® AG 300, AG 1100) against Streptococcus mutans in vitro using broth dilution assay. Materials and Methods: An ampoule of freeze-dried S. mutans NCTC reference strain was revived, and the colony-forming units (CFU) were calculated. The MIC and MBC was determined by broth dilution assay using different concentrations of Novaron® AG 300 and Novaron® AG 1100 against 1 × 105 CFU/ml of S. mutans. Results: The MIC and MBC of Novaron® AG 300 and Novaron® AG 1100 against S. mutans were found to be 40 μg/ml. Conclusions: Novaron® has anti-bacterial effect against S. mutans. Further studies are needed to explore the applicability of these silver-supported anti- microbial agents in clinical dentistry. PMID:23293483

  16. Danish Integrated Antimicrobial Resistance Monitoring and Research Program

    PubMed Central

    Heuer, Ole E.; Emborg, Hanne-Dorthe; Bagger-Skjøt, Line; Jensen, Vibeke F.; Rogues, Anne-Marie; Skov, Robert L.; Agersø, Yvonne; Brandt, Christian T.; Seyfarth, Anne Mette; Muller, Arno; Hovgaard, Karin; Ajufo, Justin; Bager, Flemming; Aarestrup, Frank M.; Frimodt-Møller, Niels; Wegener, Henrik C.; Monnet, Dominique L.

    2007-01-01

    Resistance to antimicrobial agents is an emerging problem worldwide. Awareness of the undesirable consequences of its widespread occurrence has led to the initiation of antimicrobial agent resistance monitoring programs in several countries. In 1995, Denmark was the first country to establish a systematic and continuous monitoring program of antimicrobial drug consumption and antimicrobial agent resistance in animals, food, and humans, the Danish Integrated Antimicrobial Resistance Monitoring and Research Program (DANMAP). Monitoring of antimicrobial drug resistance and a range of research activities related to DANMAP have contributed to restrictions or bans of use of several antimicrobial agents in food animals in Denmark and other European Union countries. PMID:18217544

  17. Alternatives to the use of antimicrobial agents in pig production: A multi-country expert-ranking of perceived effectiveness, feasibility and return on investment.

    PubMed

    Postma, Merel; Stärk, Katharina D C; Sjölund, Marie; Backhans, Annette; Beilage, Elisabeth Grosse; Lösken, Svenja; Belloc, Catherine; Collineau, Lucie; Iten, Denise; Visschers, Vivianne; Nielsen, Elisabeth O; Dewulf, Jeroen

    2015-03-01

    Nineteen alternatives to antimicrobial agents were ranked on perceived effectiveness, feasibility and return on investment (ROI) from 0 (not effective, not feasible, no ROI) to 10 (fully effective, completely feasible, maximum ROI) by 111 pig health experts from Belgium, Denmark, France, Germany, Sweden and Switzerland. The top 5 measures in terms of perceived effectiveness were (1) improved internal biosecurity, (2) improved external biosecurity, (3) improved climate/environmental conditions, (4) high health/Specific Pathogen Free/disease eradication and (5) increased vaccination. The top 5 measures in terms of perceived feasibility were (1) increased vaccination, (2) increased use of anti-inflammatory products, (3) improved water quality, (4) feed quality/optimization and (5) use of zinc/metals. The top 5 measures in terms of perceived ROI were (1) improved internal biosecurity, (2) zinc/metals, (3) diagnostics/action plan, (4) feed quality/optimization and (5) climate/environmental improvements. Univariate linear regression showed that veterinary practitioners rank internal biosecurity, vaccination, use of zinc/metals, feed quality optimization and climate/environmental on average highest, while researchers and professors focused more on increased use of diagnostics and action plans. Financial incentives/penalties ranked low in all countries. Belgian respondents ranked feed quality significantly lower compared to the German respondents while reduction of stocking density was ranked higher in Belgium compared to Denmark. Categorical Principal Component Analysis applied to the average ranking supported the finding that veterinary practitioners had a preference for more practical, common and already known alternatives. The results showed that improvements in biosecurity, increased use of vaccination, use of zinc/metals, feed quality improvement and regular diagnostic testing combined with a clear action plan were perceived to be the most promising alternatives to

  18. Fate of flame retardants and the antimicrobial agent triclosan in planted and unplanted biosolid-amended soils.

    PubMed

    Davis, Elizabeth F; Gunsch, Claudia K; Stapleton, Heather M

    2015-05-01

    A comprehensive understanding of the fate of contaminant-laden biosolids is needed to fully evaluate the environmental impacts of biosolid land application. The present study examined the fate of several flame retardants and triclosan in biosolid-amended soil in a 90-d greenhouse experiment. Objectives included evaluating the persistence of these compounds in soil, their phytoaccumulation potential by alfalfa (Medicago sativa), and potential degradation reactions. Concentrations of the polybrominated diphenyl ether (PBDE) congeners BDE-47 and BDE-209 and the antimicrobial triclosan declined significantly over time in biosolid-amended soil planted with alfalfa and then reached a steady state by day 28. In contrast, no significant losses of those analytes were observed from soil in nonvegetated pots. The amount of an analyte lost from vegetated soil ranged from 43% for the flame retardant di(2-ethylhexyl)-2,3,4,5-tetrabromophthalate to 61% for triclosan and was significantly and negatively related to the log octanol-water partition coefficient. Alfalfa roots and shoots were monitored for the compounds, but no clear evidence of phytoaccumulation was observed. Methyl triclosan formation was observed in the biosolid-amended soils during the study period, indicating in situ biotransformation of triclosan. The present study demonstrates that, although they are highly recalcitrant, PBDEs, selected alternate brominated flame retardants, and triclosan are capable of undergoing dissipation from biosolid-amended soils in the presence of plants. PMID:25546022

  19. In vitro activity of antimicrobial agents against streptococcus pyogenes isolated from different regions of Khyber Pakhtun Khwa Pakistan.

    PubMed

    Rizwan, Muhammad; Bakht, Jehan; Bacha, Nafees; Ahmad, Bashir

    2016-01-01

    The present study investigates the antibiotic resistance of S. pyogenes of 600 isolates collected from different body parts including throat and sputum were analyzed for their antimicrobial susceptibility to 5 antibiotics using the Kirby Bauer disc diffusion method. Based on different identification tests including, gram staining, beta hemolysis, catalase test and bacitracin sensitivity test, a total of 138 isolates were confirmed as S. pyogenes. The prevalence of S. pyogenes was 80% in sore throat and 29% in sputum samples. These isolates were further tested for antibiotics resistance using disk diffusion method. Out of 138 isolates, 49.27% isolates showed resistance towards cefixime, 28.98% towards cefotaxime and 17.39% towards ciprofloxacin, 17.39% towards ampicillin, 17.39% towards erythromycin, 15.94% towards streptomycin, 0.724% isolates towards chloromphenicol and 0% towards penicillin. Among the resistant isolates of S. pyogenes, 60.71% showed resistance towards cefixime, 57.14% towards ciprofloxacin, 57.14% towards streptomycin, 50% towards erythromycin and 25% towards cefotaxime. PMID:26826819

  20. Resistance to the Antimicrobial Agent Fosmidomycin and an FR900098 Prodrug through Mutations in the Deoxyxylulose Phosphate Reductoisomerase Gene (dxr)

    PubMed Central

    Armstrong, Christopher M.; Meyers, David J.; Imlay, Leah S.; Freel Meyers, Caren

    2015-01-01

    There is a pressing need for new antimicrobial therapies to combat globally important drug-resistant human pathogens, including Plasmodium falciparum malarial parasites, Mycobacterium tuberculosis, and Gram-negative bacteria, including Escherichia coli. These organisms all possess the essential methylerythritol phosphate (MEP) pathway of isoprenoid biosynthesis, which is not found in humans. The first dedicated enzyme of the MEP pathway, 1-deoxy-d-xylulose 5-phosphate reductoisomerase (Dxr), is inhibited by the phosphonic acid antibiotic fosmidomycin and its analogs, including the N-acetyl analog FR900098 and the phosphoryl analog fosfoxacin. In order to identify mutations in dxr that confer resistance to these drugs, a library of E. coli dxr mutants was screened at lethal fosmidomycin doses. The most resistant allele (with the S222T mutation) alters the fosmidomycin-binding site of Dxr. The expression of this resistant allele increases bacterial resistance to fosmidomycin and other fosmidomycin analogs by 10-fold. These observations confirm that the primary cellular target of fosmidomycin is Dxr. Furthermore, cell lines expressing Dxr-S222T will be a powerful tool to confirm the mechanisms of action of future fosmidomycin analogs. PMID:26124156

  1. [Recommendations from MENSURA for selection of antimicrobial agents for susceptibility testing and criteria for the interpretation of antibiograms].

    PubMed

    2000-03-01

    This document includes the recommendations from the Spanish antibiogram committee (The MENSURA group, Mesa Española de Normalización de la Sensibilidad y Resistencia a los Antimicrobianos, under the auspices of the Sociedad Española de Quimioterapia and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica) for the selection of antimicrobials for susceptibility testing. Separate tables for each group of organism with proposed susceptibility and resistance breakpoints are updated and comparatively presented with those of other groups, such us NCCLS, CA-SFM and BSAC. The susceptibility breakpoint tends to identify the fully susceptible population, which probably lacks any specific resistance mechanism. The analysis of MIC distributions for different homogeneous populations (same species) is used to define breakpoints for susceptibility. The resistance breakpoint is based on pharmacological and clinical data obtained when the corresponding antibiotic is administered with a conventional schedule. The primary objective of the Spanish MENSURA group is to contribute to the international consensus on the establishment of breakpoints. PMID:10856132

  2. Resistance to antimicrobial agents among enterococci isolated from fecal samples of wild marine species in the southern coast of Brazil.

    PubMed

    Prichula, Janira; Pereira, Rebeca Inhoque; Wachholz, Guilherme Raffo; Cardoso, Leonardo Almansa; Tolfo, Neidimar Cezar Correa; Santestevan, Naiara Aguiar; Medeiros, Aline Weber; Tavares, Maurício; Frazzon, Jeverson; d'Azevedo, Pedro Alves; Frazzon, Ana Paula Guedes

    2016-04-15

    The purpose of this study was to evaluate species distribution, antimicrobial resistance profiles, and presence of resistance genes in enterococci isolated from fecal samples of wild marine species, including seabirds (n=12), sea turtles (n=8), and mammals (n=3) found alive or dead in southern coast of Brazil. Enterococci were classified based on phenotypic and genotypic characteristics, tested for antibiotic susceptibility, and the presence of tet(S), tet(M), tet(L), mrsC, and erm(B) genes by PCR. Enterococcus faecalis and Enterococcus faecium were the most common species. Single (37.09%), double (25.80%), and multiple (16.12%) antibiotic resistance patterns were observed. Resistance to rifampicin occurred most frequently. The msrC, tet(M), and/or tet(L) genes were detected in 60.15%, 73.07%, and 23.07% of the resistant strains, respectively. In conclusion, the presence of antibiotic resistant strains in these species could be related to food web interactions and aquatic pollutants or linked to environmental resistome. PMID:26952995

  3. Identification of penicillinase producing Neisseria gonorrhoeae in Chile during clinical and microbiological study of gonococcal susceptibility to antimicrobial agents.

    PubMed Central

    Garcia Moreno, J; Dillon, J R; Arroyave, R; Maldonado, A; Fich, F; Salvo, A; Villalobos, D; Vincent, P; Pauze, M

    1987-01-01

    The first penicillinase producing isolates of Neisseria gonorrhoeae (PPNG) identified in Chile were discovered during a clinical and microbiological study to compare the efficacy of penicillin (4.8 MIU aqueous procaine penicillin G plus 1 g oral probenecid) and tetracycline (1.5 g followed by 500 mg four times daily for four days) treatment regimens for acute uncomplicated gonorrhoea. Penicillin treatment was effective in 93.1% (282) of 303 patients, whereas tetracycline was effective in 98.3% (233) of 237 patients. Six of the penicillin treatment failures were attributable to PPNG strains. In all, 21 PPNG strains were identified during the study. They were genetically identical, having a wild type auxotype, a WII/III serotype (serovar Bajk), and carrying cryptic and transfer plasmids and an Asian type penicillinase producing plasmid. In addition, 674 non-PPNG isolates were tested for their susceptibility to eight antimicrobials. Over 95% were sensitivie to 1 mg/l of penicillin, ampicillin, cefotaxime, cefuroxime, and erythromycin, over 90% were sensitive to 1 mg/l of tetracycline and 2 mg/l of thiamphenicol, and all were sensitive to spectinomycin. Of 226 non-PPNG isolates characterised for plasmid content and auxotype, 90% (205) were either wild type or proline requiring, 67% (153) carried only the cryptic plasmid, and a further 31% (71) carried both cryptic and transfer plasmids. Unusually, three of four isolates lacking the cryptic plasmid carried only the transfer plasmid. Images PMID:3102348

  4. Design, synthesis and biological evaluation of berberine-benzimidazole hybrids as new type of potentially DNA-targeting antimicrobial agents.

    PubMed

    Jeyakkumar, Ponmani; Zhang, Ling; Avula, Srinivasa Rao; Zhou, Cheng-He

    2016-10-21

    A series of novel berberine-benzimidazole derivatives were conveniently and efficiently synthesized and characterized by NMR, IR, MS and HRMS spectra. Most of the prepared compounds showed effective antimicrobial activities in contrast with clinical norfloxacin, chloromycin and fluconazole. Especially, compound 5d exhibited good anti-MRSA, anti-Escherichia coli, and anti-Salmonella typhi activity with low MIC values of 2-8 μg/mL, which were comparable or even superior to reference drugs. The preliminarily interactive investigation revealed that the most active compound 5d could effectively intercalate into DNA to form 5d-DNA complex and cleavage DNA by agarose gel electrophoresis experiments. It was also found that compound 5d was able to efficiently permeabilize the membranes of both Gram-positive (MRSA) and Gram-negative (E. coli DH52) bacteria. Experiments and molecular docking both showed that human serum albumin (HSA) could effectively transport compound 5d and hydrophobic interactions and hydrogen bonds play important roles in the association of compound 5d with HSA. PMID:27371924

  5. Resistance to the antimicrobial agent fosmidomycin and an FR900098 prodrug through mutations in the deoxyxylulose phosphate reductoisomerase gene (dxr).

    PubMed

    Armstrong, Christopher M; Meyers, David J; Imlay, Leah S; Freel Meyers, Caren; Odom, Audrey R

    2015-09-01

    There is a pressing need for new antimicrobial therapies to combat globally important drug-resistant human pathogens, including Plasmodium falciparum malarial parasites, Mycobacterium tuberculosis, and Gram-negative bacteria, including Escherichia coli. These organisms all possess the essential methylerythritol phosphate (MEP) pathway of isoprenoid biosynthesis, which is not found in humans. The first dedicated enzyme of the MEP pathway, 1-deoxy-d-xylulose 5-phosphate reductoisomerase (Dxr), is inhibited by the phosphonic acid antibiotic fosmidomycin and its analogs, including the N-acetyl analog FR900098 and the phosphoryl analog fosfoxacin. In order to identify mutations in dxr that confer resistance to these drugs, a library of E. coli dxr mutants was screened at lethal fosmidomycin doses. The most resistant allele (with the S222T mutation) alters the fosmidomycin-binding site of Dxr. The expression of this resistant allele increases bacterial resistance to fosmidomycin and other fosmidomycin analogs by 10-fold. These observations confirm that the primary cellular target of fosmidomycin is Dxr. Furthermore, cell lines expressing Dxr-S222T will be a powerful tool to confirm the mechanisms of action of future fosmidomycin analogs. PMID:26124156

  6. Evaluation of certain veterinary drug residues in food.

    PubMed

    2001-01-01

    This report presents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of residues of certain veterinary drugs in food and to recommend maximum levels for such residues in food. The first part of the report considers the interpretation of data on inhibition of cholinesterase activity and recommendations arising from an informal meeting on harmonization with the Joint FAO/WHO Meeting on Pesticide Residues. A summary follows of the Committee's evaluations of toxicological and residue data on a variety of veterinary drugs: one anthelminthic agent (ivermectin); four antimicrobial agents (flumequine, lincomycin, oxytetracycline and tilmicosin); six insecticides (cyhalothrin, cypermethrin, alpha-cypermethrin, dicyclanil, permethrin and metrifonate (trichlorfon)); and one production aid (melengestrol acetate). Annexed to the report are a summary of the Committee's recommendations on these drugs, including Acceptable Daily Intakes and Maximum Residue Limits and further information required. PMID:11402526

  7. The importance of expressing antimicrobial agents on water basis in growth/no growth interface models: a case study for Zygosaccharomyces bailii.

    PubMed

    Dang, T D T; Vermeulen, A; Mertens, L; Geeraerd, A H; Van Impe, J F; Devlieghere, F

    2011-01-31

    In a previous study on Zygosaccharomyces bailii, three growth/no growth models have been developed, predicting growth probability of the yeast at different conditions typical for acidified foods (Dang, T.D.T., Mertens, L., Vermeulen, A., Geeraerd, A.H., Van Impe, J.F., Debevere, J., Devlieghere, F., 2010. Modeling the growth/no growth boundary of Z. bailii in acidic conditions: A contribution to the alternative method to preserve foods without using chemical preservatives. International Journal of Food Microbiology 137, 1-12). In these broth-based models, the variables were pH, water activity and acetic acid, with acetic acid concentration expressed in volume % on the total culture medium (i.e., broth). To continue the previous study, validation experiments were performed for 15 selected combinations of intrinsic factors to assess the performance of the model at 22°C (60days) in a real food product (ketchup). Although the majority of experimental results were consistent, some remarkable deviations between prediction and validation were observed, e.g., Z. bailii growth occurred in conditions where almost no growth had been predicted. A thorough investigation revealed that the difference between two ways of expressing acetic acid concentration (i.e., on broth basis and on water basis) is rather significant, particularly for media containing high amounts of dry matter. Consequently, the use of broth-based concentrations in the models was not appropriate. Three models with acetic acid concentration expressed on water basis were established and it was observed that predictions by these models well matched the validation results; therefore a "systematic error" in broth-based models was recognized. In practice, quantities of antimicrobial agents are often calculated based on the water content of food products. Hence, to assure reliable predictions and facilitate the application of models (developed from lab media with high dry matter contents), it is important to express

  8. Activity of telavancin and comparator antimicrobial agents tested against Staphylococcus spp. isolated from hospitalised patients in Europe (2007-2008).

    PubMed

    Mendes, Rodrigo E; Sader, Helio S; Jones, Ronald N

    2010-10-01

    The activity of telavancin was evaluated against Staphylococcus spp. collected from European hospitals as part of an international surveillance study (2007-2008). A total of 7534 staphylococcal clinical isolates [5726 Staphylococcus aureus and 1808 coagulase-negative staphylococci (CoNS)] were included. Isolates were tested for susceptibility according to reference methods and minimum inhibitory concentration (MIC) values were interpreted based on Clinical and Laboratory Standards Institute (CLSI) 2010 and European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2009 criteria. Telavancin breakpoints approved by the US Food and Drug Administration (FDA) were applied. Telavancin activity was evaluated against meticillin-resistant S. aureus (MRSA) displaying several antibiogram resistance patterns, including multidrug-resistant isolates. Telavancin was active against S. aureus [MIC(50/90) values (MICs for 50% and 90% of the isolates, respectively)=0.12/0.25mg/L; 100.0% susceptible] and CoNS (MIC(50/90)=0.12/0.25mg/L), inhibiting all isolates at < or =0.5mg/L. Similar results were observed when S. aureus were stratified by year or country of origin (MIC(50/90)=0.12/0.25mg/L). When MRSA isolates were clustered according to 48 different resistance patterns, telavancin showed consistent MIC(90) values (0.25mg/L) regardless of multidrug resistance. Amongst CoNS, telavancin was slightly more active against Staphylococcus capitis, Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus lugdunensis and Staphylococcus xylosus (MIC(50)=0.12 mg/L) compared with Staphylococcus haemolyticus, Staphylococcus saprophyticus and Staphylococcus warneri (MIC(50)=0.25mg/L). Overall, telavancin exhibited MIC(90) results two- to eight-fold lower than comparators (daptomycin, quinupristin/dalfopristin, vancomycin and linezolid). Based upon MIC(90) values, telavancin demonstrated potent in vitro activity against a contemporary (2007-2008) collection of Staphylococcus spp

  9. T4-like phage Bp7, a potential antimicrobial agent for controlling drug-resistant Escherichia coli in chickens.

    PubMed

    Zhang, Can; Li, Wenli; Liu, Wenhua; Zou, Ling; Yan, Chen; Lu, Kai; Ren, Huiying

    2013-09-01

    Chicken-pathogenic Escherichia coli is severely endangering the poultry industry in China and worldwide, and antibiotic therapy is facing an increasing problem of antibiotic resistance. Bacteriophages can kill bacteria with no known activity in human or animal cells, making them an attractive alternative to antibiotics. In this study, we present the characteristics of a novel virulent bacteriophage, Bp7, specifically infecting pathogenic multidrug-resistant E. coli. Phage Bp7 was isolated from chicken feces. Bp7 belongs to the family Myoviridae, possessing an elongated icosahedral head and contractile sheathed tail. It has a 168-kb double-stranded DNA genome. For larger yields, its optimal multiplicity of infection (MOI) to infect E. coli was about 0.001. The latent period was 10 to 15 min, and the burst size was 90 PFU/infected cell. It was stable both at pH 5.0 to 10.0 and at 40°C or 50°C for at least 1 h. Bp7 could infect 46% of pathogenic clinical E. coli strains. Bp7 harbored 791 open reading frames (ORFs) and 263 possible genes. Among the 263 genes, 199 possessed amino acid sequence identities with ORFs of phage T4, 62 had identities with other T4-like phages, and only one lacked any database match. The genome of Bp7 manifested obvious division and rearrangement compared to phages T4, JS98, and IME08. Bp7 is a new member of the "T4-like" genus, family Myoviridae. Its wide host range, strong cell-killing activity, and high stability to pH make it an alternative to antimicrobials for controlling drug-resistant E. coli in chickens. PMID:23835183

  10. Alternative Antimicrobial Approach: Nano-Antimicrobial Materials

    PubMed Central

    Beyth, Nurit; Houri-Haddad, Yael; Domb, Avi; Khan, Wahid; Hazan, Ronen

    2015-01-01

    Despite numerous existing potent antibiotics and other antimicrobial means, bacterial infections are still a major cause of morbidity and mortality. Moreover, the need to develop additional bactericidal means has significantly increased due to the growing concern regarding multidrug-resistant bacterial strains and biofilm associated infections. Consequently, attention has been especially devoted to new and emerging nanoparticle-based materials in the field of antimicrobial chemotherapy. The present review discusses the activities of nanoparticles as an antimicrobial means, their mode of action, nanoparticle effect on drug-resistant bacteria, and the risks attendant on their use as antibacterial agents. Factors contributing to nanoparticle performance in the clinical setting, their unique properties, and mechanism of action as antibacterial agents are discussed in detail. PMID:25861355

  11. Efficacy of Lysophosphatidylcholine in Combination with Antimicrobial Agents against Acinetobacter baumannii in Experimental Murine Peritoneal Sepsis and Pneumonia Models.

    PubMed

    Parra Millán, R; Jiménez Mejías, M E; Sánchez Encinales, V; Ayerbe Algaba, R; Gutiérrez Valencia, A; Pachón Ibáñez, M E; Díaz, C; Pérez Del Palacio, J; López Cortés, L F; Pachón, J; Smani, Y

    2016-08-01

    Immune response stimulation to prevent infection progression may be an adjuvant to antimicrobial treatment. Lysophosphatidylcholine (LPC) is an immunomodulator involved in immune cell recruitment and activation. In this study, we aimed to evaluate the efficacy of LPC in combination with colistin, tigecycline, or imipenem in experimental murine models of peritoneal sepsis and pneumonia. We used Acinetobacter baumannii strain Ab9, which is susceptible to colistin, tigecycline, and imipenem, and multidrug-resistant strain Ab186, which is susceptible to colistin and resistant to tigecycline and imipenem. Pharmacokinetic and pharmacodynamic parameters for colistin, tigecycline, and imipenem and the 100% minimal lethal dose (MLD100) were determined for both strains. The therapeutic efficacies of LPC, colistin (60 mg/kg of body weight/day), tigecycline (10 mg/kg/day), and imipenem (180 mg/kg/day), alone or in combination, were assessed against Ab9 and Ab186 at the MLD100 in murine peritoneal sepsis and pneumonia models. The levels of pro- and anti-inflammatory cytokines, i.e., tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10), were determined by enzyme-linked immunosorbent assay (ELISA) for the same experimental models after inoculating mice with the MLD of both strains. LPC in combination with colistin, tigecycline, or imipenem markedly enhanced the bacterial clearance of Ab9 and Ab186 from the spleen and lungs and reduced bacteremia and mouse mortality rates (P < 0.05) compared with those for colistin, tigecycline, and imipenem monotherapies. Moreover, at 4 h post-bacterial infection, Ab9 induced higher TNF-α and lower IL-10 levels than those with Ab186 (4 μg/ml versus 3 μg/ml [P < 0.05] and 2 μg/ml versus 3.4 μg/ml [P < 0.05], respectively). LPC treatment combined with colistin, tigecycline, or imipenem modestly reduced the severity of infection by A. baumannii strains with different resistance phenotypes compared to LPC monotherapy in both

  12. Classification of OprD sequence and correlation with antimicrobial activity of carbapenem agents in Pseudomonas aeruginosa clinical isolates collected in Japan.

    PubMed

    Sanbongi, Yumiko; Shimizu, Atsuyuki; Suzuki, Takahisa; Nagaso, Hiroshi; Ida, Takashi; Maebashi, Kazunori; Gotoh, Naomasa

    2009-07-01

    A total of 99 clinical isolates of metallo-ss-lactamase-negative Pseudomonas aeruginosa collected in Japan between 1998 and 2001 were studied for their susceptibilities to carbapenem agents and corresponding oprD gene mutations. The OprD sequence of each strain was grouped into two major classes, based on the pattern of alterations. Eighty strains (80.8%) were so-called 'full length type', whose OprD proteins were fully encoded. The remaining 19 strains (19.2%) were so-called 'defective type', which possessed deletions or major alterations that might cause conformational changes in the OprD porin protein. The changes in 'defective type' strains led to 15-, 17- and 23-fold increases in the geometric mean MIC for imipenem, meropenem and biapenem compared with 'full length type' strains, respectively. 'Full length type' strains were further classified into six carbapenem susceptible types with the exception of four carbapenem-resistant subtypes with additional amino acid substitutions at D43, G183, R154, G314, G316. However, 'defective type' strains were classified into four types as follows: 10 strains which contained a stop codon within the coding region; six strains which contained IS; one strain with a short deletion near the C-terminal domain; and two strains without a stop codon in the sequenced region. Western blot analysis using OprD antibody showed that binding abilities of OprD proteins against 'full length type' strains were normal, whereas those against 'defective type' strains were lost without exception. These results indicate that OprD structure and antimicrobial activities for carbapenem agents proved to be highly correlated in P. aeruginosa. PMID:19563394

  13. [Susceptibilities of clinical bacterial isolates to antimicrobial agents. A study mainly focused on imipenem. Research Group for Testing Imipenem Susceptibility on Clinical Isolates].

    PubMed

    Igari, J

    1990-10-01

    We investigated susceptibilities of clinical bacterial isolates to imipenem (IPM) and other antimicrobial agents at 459 hospital laboratories throughout Japan from September to December of 1988. In this study, identification and susceptibility testing were performed at each hospital laboratory and the tests were carried out according to the 1-dilution or 3-dilution disc technique in which susceptibilities are classified into 4 grades: , ++, + and -. IPM had significantly high activity against Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Neisseria gonorrhoeae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae, Salmonella spp., Citrobacter freundii, Proteus mirabilis, Providencia rettgeri, Acinetobacter calcoaceticus, Moraxella catarrhalis, Alcaligenes spp., Peptococcus spp./Peptostreptococcus spp., Bacteroides fragilis and Bacteroides spp. and should slightly lower activities on coagulase-negative staphylococci (CNS), Enterococcus faecalis, Haemophilus influenzae, Serratia marcescens, Proteus vulgaris, Providencia stuartii and Pseudomonas aeruginosa than on the above mentioned bacteria. In a comparative study on activities of IPM against bacteria from different clinical sources, no remarkable differences were found due to different sources among S. pneumoniae, E. faecalis, H. influenzae, E. coli, K. pneumoniae, E. cloacae, C. freundii, P. mirabilis or A. calcoaceticus, whereas slight differences were found among Staphylococcus aureus, CNS, S. marcescens and P. aeruginosa. PMID:2086814

  14. Ziziphora clinopodioides Essential Oil and Nisin as Potential Antimicrobial Agents against Escherichia coli O157:H7 in Doogh (Iranian Yoghurt Drink).

    PubMed

    Shahbazi, Yasser

    2015-01-01

    The aim of the present study was to evaluate the effects of Ziziphora clinopodioides essential oil (0.1 and 0.2%) and nisin (250 and 500 IU/mL) separately and in combination on survival of Escherichia coli O157:H7 inoculated in Doogh (Iranian yoghurt drink) during storage under refrigerated temperature (4 ± 1°C) for 9 days. Viability of Lactobacillus casei at different concentrations of Z. clinopodioides essential oil (0.1 and 0.2%) in Doogh was also examined. The major components were carvacrol (64.22%), thymol (19.22%), γ-terpinene (4.63%), and p-cymene (4.86%). There was no significant difference (p > 0.05) between samples treated with nisin and those of untreated samples. Samples treated with both concentrations of the essential oil (0.1 and 0.2%) showed populations of E. coli O157:H7 significantly (p < 0.05) lower than those of untreated samples. The essential oil of Z. clinopodioides in combination with nisin had a potential synergistic effect against E. coli O157:H7 in Doogh samples after 5 days. The count of L. casei was not inhibited by different concentrations of the Z. clinopodioides essential oil. It is concluded that the leaf essential oil of Z. clinopodioides in combination with nisin can be applied as alternative antimicrobial agents in Doogh to inhibit the growth of E. coli O157:H7. PMID:26783466

  15. Subinhibitory Concentrations of Antimicrobial Agents Reduce the Uptake of Legionella pneumophila into Acanthamoeba castellanii and U937 Cells by Altering the Expression of Virulence-Associated Antigens

    PubMed Central

    Lück, P. Christian; Schmitt, Jürgen W.; Hengerer, Arne; Helbig, Jürgen H.

    1998-01-01

    We determined the MICs of ampicillin, ciprofloxacin, erythromycin, imipenem, and rifampin for two clinical isolates of Legionella pneumophila serogroup 1 by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay and by quantitative culture. To test the influence of subinhibitory concentrations (sub-MICs) of antimicrobial agents on Legionella uptake into Acanthamoeba castellanii and U937 macrophage-like cells, both strains were pretreated with 0.25 MICs of the antibiotics for 24 h. In comparison to that for the untreated control, subinhibitory concentrations of antibiotics significantly reduced Legionella uptake into the host cells. Measurement of the binding of monoclonal antibodies against several Legionella antigens by enzyme-linked immunoassays indicated that sub-MIC antibiotic treatment reduced the expression of the macrophage infectivity potentiator protein (Mip), the Hsp 60 protein, the outer membrane protein (OmpM), an as-yet-uncharacterized protein of 55 kDa, and a few lipopolysaccharide (LPS) epitopes. In contrast, the expression of some LPS epitopes recognized by monoclonal antibodies 8/5 and 30/4 as well as a 45-kDa protein, a 58-kDa protein, and the major outer membrane protein (OmpS) remained unaffected. PMID:9797218

  16. Ziziphora clinopodioides Essential Oil and Nisin as Potential Antimicrobial Agents against Escherichia coli O157:H7 in Doogh (Iranian Yoghurt Drink)

    PubMed Central

    Shahbazi, Yasser

    2015-01-01

    The aim of the present study was to evaluate the effects of Ziziphora clinopodioides essential oil (0.1 and 0.2%) and nisin (250 and 500 IU/mL) separately and in combination on survival of Escherichia coli O157:H7 inoculated in Doogh (Iranian yoghurt drink) during storage under refrigerated temperature (4 ± 1°C) for 9 days. Viability of Lactobacillus casei at different concentrations of Z. clinopodioides essential oil (0.1 and 0.2%) in Doogh was also examined. The major components were carvacrol (64.22%), thymol (19.22%), γ-terpinene (4.63%), and p-cymene (4.86%). There was no significant difference (p > 0.05) between samples treated with nisin and those of untreated samples. Samples treated with both concentrations of the essential oil (0.1 and 0.2%) showed populations of E. coli O157:H7 significantly (p < 0.05) lower than those of untreated samples. The essential oil of Z. clinopodioides in combination with nisin had a potential synergistic effect against E. coli O157:H7 in Doogh samples after 5 days. The count of L. casei was not inhibited by different concentrations of the Z. clinopodioides essential oil. It is concluded that the leaf essential oil of Z. clinopodioides in combination with nisin can be applied as alternative antimicrobial agents in Doogh to inhibit the growth of E. coli O157:H7. PMID:26783466

  17. Antimicrobial activity of natural Respitol-B and its main components against poultry microorganisms.

    PubMed

    Mahboubi, Mohaddese; Kazempour, Nastaran; Valian, Mahdi

    2013-10-01

    Poultries are infected to different kinds of microbial infections during their growth. For prevent of these diseases, many farmers use the synthetic antimicrobial agents. Whereas, the poultries participate in food cycle of human, the residues of these agents enter in human and cause many undesired side effects. In this study, the antimicrobial activity of Respitol-B and its main components (eucalyptus oil and menthol) was evaluated on different kinds of microorganisms including gram positive, gram negative bacteria, yeast and fungi in vitro conditions by disc diffusion and micro broth dilution assays. The gram positive bacteria, yeast and fungi is more sensitive than Gram negative ones to Respitol-B. Pseudomonas aeruginosa, Escherichia coli and Salmonella typhimurium is less sensitive to Respitol-B. Evaluation of menthol and eucalyptus oil for their antimicrobial activities exhibited that the antimicrobial activity of menthol is higher than that of eucalyptus oil. Eucalyptus oil had the best effect on Vibrio cholerae, Staphylococcus aureus, Aspergillus flavus but had no effect on others. The antimicrobial activity of menthol is observable and its presence in Respitol-B enhances the antimicrobial activity of Respitol-B. Respitol-B as a 100% herbal drug has antimicrobial effect and can be used as alternative therapy for preventing and controlling of infections. PMID:24502173

  18. Targeting the Replication Initiator of the Second Vibrio Chromosome: Towards Generation of Vibrionaceae-Specific Antimicrobial Agents

    PubMed Central

    Yamaichi, Yoshiharu; Duigou, Stéphane; Shakhnovich, Elizabeth A.; Waldor, Matthew K.

    2009-01-01

    The Vibrionaceae is comprised of numerous aquatic species and includes several human pathogens, such as Vibrio cholerae, the cause of cholera. All organisms in this family have two chromosomes, and replication of the smaller one depends on rctB, a gene that is restricted to the Vibrionaceae. Given the increasing prevalence of multi-drug resistance in pathogenic vibrios, there is a need for new targets and drugs to combat these pathogens. Here, we carried out a high throughput cell-based screen to find small molecule inhibitors of RctB. We identified a compound that blocked growth of an E. coli strain bearing an rctB-dependent plasmid but did not influence growth of E. coli lacking this plasmid. This compound, designated vibrepin, had potent cidal activity against V. cholerae and inhibited the growth of all vibrio species tested. Vibrepin blocked RctB oriCII unwinding, apparently by promoting formation of large non-functional RctB complexes. Although vibrepin also appears to have targets other than RctB, our findings suggest that RctB is an attractive target for generation of novel antibiotics that only block growth of vibrios. Vibrio-specific agents, unlike antibiotics currently used in clinical practice, will not engender resistance in the normal human flora or in non-vibrio environmental microorganisms. PMID:19936046

  19. [Backup support from the independent laboratory to the hospital for infection control of antimicrobial agent-resistant bacteria].

    PubMed

    Komatsu, Masaru

    2012-10-01

    Because commercial laboratories have far less opportunity for direct communication with clinicians in comparison with hospitals, they need to maintain closer contact regarding the evaluation of prophlogistic bacterial isolates through such communication tools as the telephone, and need to include more comments in reports to avoid misunderstandings by clinicians. Commercial laboratories handle enormous numbers of strains of microorganisms that have been isolated from various regions and, therefore, they have a great deal of information important for public health that relates to pathogens causing community-acquired and healthcare associated infection. Returning such information to society provides useful data for selecting antibacterial agents and taking measures against healthcare-associated infection. Many medical facilities that outsource microorganism tests to commercial laboratories do not have a resident specialist in clinical microbiology, and it is difficult for such facilities to centrally manage test data within the facility, possibly causing increased incidents of delay in the early detection of a mass outbreak of healthcare-associated infection; therefore, commercial laboratories should immediately develop a resource of experts in their organization. Although there are professional certification systems in Japan such as the Infection Control Microbiological Technologist (ICMT) and over 500 technicians are certified, the majority of these technicians belong to hospitals. In the future, support of the clinical education of technicians working in laboratories should be considered at the society level. PMID:23323460

  20. In vitro activities of 28 antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA) from a clinical setting in Malaysia.

    PubMed

    Neela, V; Sasikumar, M; Ghaznavi, G R; Zamberi, S; Mariana, S

    2008-09-01

    Methicillin-resistant Staphylococcus aureus (MRSA), an established nosocomial and emerging community pathogen associated with many fatalities due to its hyper-virulence and multiple drug resistant properties, is on the continuous rise. To update the current status on the susceptibility of local MRSA isolates to various classes of antibiotics and to identify the most potent antibiotics, thirty-two clinical isolates comprised of hospital acquired (HA) and community acquired (CA) infections were investigated by disk diffusion test. Of the 32 MRSA isolates, 14 (43.75%) and 18 (56.25%) were community and hospital acquired MRSA, respectively. All isolates were multiple drug resistant to more than 3 classes of antibiotics despite the source or specimen from which it was isolated. The oxacillin MICs for all isolates ranged from 2 to > or = 256 microg/ml. Twenty-five of 26 erythromycin-resistant MRSA isolates exhibited an inducible MLS(B) resistance phenotype while one showed an MS phenotype. More than half the isolates (68.75%) were resistant to at least one of the six aminoglycosides tested, with netilmicin as the most susceptible. The most effective antistaphylococcal agents were linezolid, vancomycin, teicoplanin and quinupristin/dalfopristin exhibited 100% susceptibility. Since MRSA is under continuous pressure of acquiring multiple drug resistance, it is imperative to focus routine surveillance on HA and CA-MRSA strains to monitor and limit the spread of this organism. PMID:19058585

  1. Identification and characterization of a novel antimicrobial peptide from the venom of the ant Tetramorium bicarinatum.

    PubMed

    Rifflet, Aline; Gavalda, Sabine; Téné, Nathan; Orivel, Jérôme; Leprince, Jérôme; Guilhaudis, Laure; Génin, Eric; Vétillard, Angélique; Treilhou, Michel

    2012-12-01

    A novel antimicrobial peptide, named Bicarinalin, has been isolated from the venom of the ant Tetramorium bicarinatum. Its amino acid sequence has been determined by de novo sequencing using mass spectrometry and by Edman degradation. Bicarinalin contained 20 amino acid residues and was C-terminally amidated as the majority of antimicrobial peptides isolated to date from insect venoms. Interestingly, this peptide had a linear structure and exhibited no meaningful similarity with any known peptides. Antibacterial activities against Staphylococcus aureus and S. xylosus strains were evaluated using a synthetic replicate. Bicarinalin had a potent and broad antibacterial activity of the same magnitude as Melittin and other hymenopteran antimicrobial peptides such as Pilosulin or Defensin. Moreover, this antimicrobial peptide has a weak hemolytic activity compared to Melittin on erythrocytes, suggesting potential for development into an anti-infective agent for use against emerging antibiotic-resistant pathogens. PMID:22960382

  2. 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

  3. Evaluation of certain veterinary drug residues in food.

    PubMed

    2002-01-01

    This report presents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of residues of certain veterinary drugs in food and to recommend maximum levels for such residues in food. The first part of the report considers risk assessment principles and presents the views of the Committee on the FAO/WHO Project to update principles and methods for the risk assessment of chemicals in food. Summaries follow of the Committee's evaluations of toxicological and residue data on a variety of veterinary drugs: three anthelminthic agents (doramectin, ivermectin and tiabendazole), seven antimicrobial agents (cefuroxime, dihydrostreptomycin and streptomycin, lincomycin, neomycin, oxytetracycline and thiamphenicol), four insecticides (cyhalothrin, cypermethrin and alpha-cypermethrin, and phoxim) and one production aid (melengestrol acetate). Annexed to the report is a summary of the Committee's recommendations on these drugs, including Acceptable Daily Intakes and Maximum Residue Limits and further information required. PMID:12592988

  4. Antimicrobial Stewardship

    PubMed Central

    Doron, Shira; Davidson, Lisa E.

    2011-01-01

    Antimicrobial resistance is increasing; however, antimicrobial drug development is slowing. Now more than ever before, antimicrobial stewardship is of the utmost importance as a way to optimize the use of antimicrobials to prevent the development of resistance and improve patient outcomes. This review describes the why, what, who, how, when, and where of antimicrobial stewardship. Techniques of stewardship are summarized, and a plan for implementation of a stewardship program is outlined. PMID:22033257

  5. Model Membrane and Cell Studies of Antimicrobial Activity of Melittin Analogues.

    PubMed

    Jamasbi, Elaheh; Mularski, Anna; Separovic, Frances

    2016-01-01

    Melittin is a 26 residue peptide and the major component of bee (Apis mellifera) venom. Although melittin has both anticancer and antimicrobial properties, utilization has been limited due to its high lytic activity against eukaryotic cells. The mechanism of this lytic activity remains unclear but several mechanisms have been proposed, including pore formation or a detergent like mechanism, which result in lysis of cell membranes. Several analogues of melittin have been synthesized to further understand the role of specific residues in its antimicrobial and lytic activity. Melittin analogues that have a proline residue substituted for an alanine, lysine or cysteine have been studied with both model membrane systems and living cells. These studies have revealed that the proline residue plays a critical role in antimicrobial activity and cytotoxicity. Analogues lacking the proline residue and dimers of these analogues displayed decreased cytotoxicity and minimum inhibition concentrations. Several mutant studies have shown that, when key substitutions are made, the resultant peptides have more activity in terms of pore formation than the native melittin. Designing analogues that retain antimicrobial and anticancer activity while minimizing haemolytic activity will be a promising way to utilize melittin as a potential therapeutic agent. PMID:26139117

  6. 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.

  7. Effect of quinupristin/dalfopristin on 3T3 and Eahy926 cells in vitro in comparison to other antimicrobial agents with the potential to induce infusion phlebitis.

    PubMed

    Kruse, Matthias; Kilic, Bülent; Flick, Burkhard; Stahlmann, Ralf

    2007-06-01

    Infusion phlebitis is a common clinical problem that is observed with some antimicrobial agents, when being administered intravenously. In this study, cultured murine fibroblasts and immortalised human endothelial cells were exposed to three antibiotics at clinically relevant concentrations to assess their toxic potential in two established cytotoxicity assays. BALB/c 3T3 fibroblasts and Eahy926 endothelial cells were exposed to quinupristin/dalfopristin (QD), erythromycin and levofloxacin at increasing concentrations. For assessment of cytotoxicity the cells were incubated with neutral red (NR) or stained with crystal violet (CV). Measurements were done by photometry. At the concentration range tested QD and erythromycin showed a concentration-dependent cytotoxic effect in both cell cultures. In 3T3 cells the half-maximal effect concentration (EC50) was 20 mg/l for QD and 340 mg/l for erythromycin in the NR uptake test and 12 and 200 mg/l, respectively, in the CV assay. In Eahy926 cells the EC50 was 50 mg/l for QD and 880 mg/l for erythromycin in the NR uptake test and 40 and 750 mg/l, respectively, in the CV assay. No EC50 could be established in both cell types for levofloxacin. Eahy926 cells were less sensitive to cytotoxic stimuli than 3T3 fibroblasts. Cytotoxic effects in both cell cultures occurred in the following order: QD > erythromycin > levofloxacin. This ranking correlates well with the frequency of local adverse effects observed with the infusion of these antibiotics in patients. Thus, these in vitro assays may serve as an estimate for the prediction of local tolerability of antibiotics when administered parenterally. PMID:17119926

  8. Determining the ecological impacts of organic contaminants in biosolids using a high-throughput colorimetric denitrification assay: a case study with antimicrobial agents.

    PubMed

    Holzem, R M; Stapleton, H M; Gunsch, C K

    2014-01-01

    Land application accounts for ∼ 50% of wastewater solid disposal in the United States. Still, little is known regarding the ecological impacts of nonregulated contaminants found in biosolids. Because of the myriad of contaminants, there is a need for a rapid, high-throughput method to evaluate their ecotoxicity. Herein, we developed a novel assay that measures denitrification inhibition in a model denitrifier, Paracoccus denitrificans Pd1222. Two common (triclosan and triclocarban) and four emerging (2,4,5 trichlorophenol, 2-benzyl-4-chlorophenol, 2-chloro-4-phenylphenol, and bis(5-chloro-2-hydroxyphenyl)methane) antimicrobial agents found in biosolids were analyzed. Overall, the assay was reproducible and measured impacts on denitrification over 3 orders of magnitude exposure. The lowest observable adverse effect concentrations (LOAECs) were 1.04 μM for triclosan, 3.17 μM for triclocarban, 0.372 μM for bis-(5-chloro-2-hydroxyphenyl)methane, 4.89 μM for 2-chloro-4-phenyl phenol, 45.7 μM for 2-benzyl-4-chorophenol, and 50.6 μM for 2,4,5-trichlorophenol. Compared with gene expression and cell viability based methods, the denitrification assay was more sensitive and resulted in lower LOAECs. The increased sensitivity, low cost, and high-throughput adaptability make this method an attractive alternative for meeting the initial testing regulatory framework for the Federal Insecticide, Fungicide, and Rodenticide Act, and recommended for the Toxic Substances Control Act, in determining the ecotoxicity of biosolids-derived emerging contaminants. PMID:24410196

  9. Emergence in Vietnam of Streptococcus pneumoniae Resistant to Multiple Antimicrobial Agents as a Result of Dissemination of the Multiresistant Spain23F-1 Clone

    PubMed Central

    Parry, Christopher M.; Duong, Nguyen Minh; Zhou, Jiaji; Mai, Nguyen Thi Hoang; Diep, To Song; Thinh, Le Quoc; Wain, John; Van Vinh Chau, Nguyen; Griffiths, David; Day, Nicholas P. J.; White, Nicholas J.; Hien, Tran Tinh; Spratt, Brian G.; Farrar, Jeremy J.

    2002-01-01

    Surveillance for Streptococcus pneumoniae resistant to penicillin and other antimicrobial agents is necessary to define the optimal empirical antibiotic therapy for meningitis in resource-poor countries such as Vietnam. The clinical and microbiological features of 100 patients admitted to the Centre for Tropical Diseases in Ho Chi Minh City, Vietnam, between 1993 and 2002 with invasive pneumococcal disease were studied. A penicillin-nonsusceptible pneumococcus (MIC, ≥0.1 μg/ml) was isolated from the blood or cerebrospinal fluid of 8% of patients (2 of 24) between 1993 and 1995 but 56% (20 of 36) during 1999 to 2002 (P < 0.0001). Pneumococcal isolates resistant to penicillin (MIC, ≥2.0 μg/ml) increased from 0% (0 of 24) to 28% (10 of 36) (P = 0.002). Only one isolate was ceftriaxone resistant (MIC, 2.0 μg/ml). Penicillin-nonsusceptible pneumococci were isolated from 78% of children younger than 15 years (28 of 36) compared with 25% of adults (16 of 64) (P = 0.0001). Isolation of a penicillin-nonsusceptible pneumococcus in adults with meningitis was independently associated with referral from another hospital (P = 0.005) and previous antibiotic therapy (P = 0.025). Multilocus sequence typing showed that 86% of the invasive penicillin-resistant pneumococcus isolates tested (12 of 14) were of the Spain23F-1 clone. The serotypes of >95% of the penicillin-nonsusceptible pneumococci were included in the currently available pneumococcal vaccines. Our findings point to the recent introduction and spread of the Spain23F-1 clone of penicillin-resistant pneumococci in Vietnam. Simple clinical predictors can be used to guide empirical antibiotic therapy of meningitis. Pneumococcal vaccination may help to control this problem. PMID:12384358

  10. Antimicrobial Stewardship Programs in Health Care Systems

    PubMed Central

    MacDougall, Conan; Polk, Ron E.

    2005-01-01

    Antimicrobial stewardship programs in hospitals seek to optimize antimicrobial prescribing in order to improve individual patient care as well as reduce hospital costs and slow the spread of antimicrobial resistance. With antimicrobial resistance on the rise worldwide and few new agents in development, antimicrobial stewardship programs are more important than ever in ensuring the continued efficacy of available antimicrobials. The design of antimicrobial management programs should be based on the best current understanding of the relationship between antimicrobial use and resistance. Such programs should be administered by multidisciplinary teams composed of infectious diseases physicians, clinical pharmacists, clinical microbiologists, and infection control practitioners and should be actively supported by hospital administrators. Strategies for changing antimicrobial prescribing behavior include education of prescribers regarding proper antimicrobial usage, creation of an antimicrobial formulary with restricted prescribing of targeted agents, and review of antimicrobial prescribing with feedback to prescribers. Clinical computer systems can aid in the implementation of each of these strategies, especially as expert systems able to provide patient-specific data and suggestions at the point of care. Antibiotic rotation strategies control the prescribing process by scheduled changes of antimicrobial classes used for empirical therapy. When instituting an antimicrobial stewardship program, a hospital should tailor its choice of strategies to its needs and available resources. PMID:16223951

  11. Cellulose Nanocrystals from Forest Residues as Reinforcing Agents for Composites: A Study from Macro- to Nano-Dimensions.

    PubMed

    Moriana, Rosana; Vilaplana, Francisco; Ek, Monica

    2016-03-30

    This study investigates for the first time the feasibility of extracting cellulose nanocrystals (CNCs) from softwood forestry logging residues (woody chips, branches and pine needles), with an obtained gravimetric yield of over 13%. Compared with the other residues, woody chips rendered a higher yield of bleached cellulosic fibers with higher hemicellulose, pectin and lignin content, longer diameter, and lower crystallinity and thermal stability. The isolation of CNCs from these bleached cellulosic fibers was verified by the removal of most of their amorphous components, the increase in the crystallinity index, and the nano-dimensions of the individual crystals. The differences in the physico-chemical properties of the fibers extracted from the three logging residues resulted in CNCs with specific physico-chemical properties. The potential of using the resulting CNCs as reinforcements in nanocomposites was discussed in terms of aspect ratio, crystallinity and thermal stability. PMID:26794957

  12. Editorial of the Special Issue Antimicrobial Polymers

    PubMed Central

    Piozzi, Antonella; Francolini, Iolanda

    2013-01-01

    The special issue “Antimicrobial Polymers” includes research and review papers concerning the recent advances on preparation of antimicrobial polymers and their relevance to industrial settings and biomedical field. Antimicrobial polymers have recently emerged as promising candidates to fight microbial contamination onto surfaces thanks to their interesting properties. In this special issue, the main strategies pursued for developing antimicrobial polymers, including polymer impregnation with antimicrobial agents or synthesis of polymers bearing antimicrobial moieties, were discussed. The future application of these polymers either in industrial or healthcare settings could result in an extremely positive impact not only at the economic level but also for the improvement of quality of life. PMID:24005863

  13. Use of kidney inhibition swab test to evaluate antimicrobial residues in pork kidney from a market survey in Fargo, North Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: The USDA-Food Safety and Inspection Service (FSIS) recently changed the on-site antimicrobial screening method to the Kidney Inhibition Swab (KIS™) test to be used at all livestock slaughter establishments. Although the newly adapted screening method can detect different classes of an...

  14. Antimicrobial peptides: premises and promises.

    PubMed

    Reddy, K V R; Yedery, R D; Aranha, C

    2004-12-01

    Antimicrobial peptides (AMPs) are an important component of the natural defences of most living organisms against invading pathogens. These are relatively small (< 10kDa), cationic and amphipathic peptides of variable length, sequence and structure. During the past two decades several AMPs have been isolated from a wide variety of animals, both vertebrates and invertebrates, and plants as well as from bacteria and fungi. Most of these peptides are obtained from different sources like macrophages, neutrophils, epithelial cells, haemocytes, fat body, reproductive tract, etc. These peptides exhibit broad-spectrum activity against a wide range of microorganisms including Gram-positive and Gram-negative bacteria, protozoa, yeast, fungi and viruses. A few peptides have also been found to be cytotoxic to sperm and tumour cells. AMPs are classified based on the three dimensional structural studies carried out with the help of NMR. The peptides are broadly classified into five major groups namely (a) peptides that form alpha-helical structures, (b) peptides rich in cysteine residues, (c) peptides that form beta-sheet, (d) peptides rich in regular amino acids namely histatin, arginine and proline and (e) peptides composed of rare and modified amino acids. Most of these peptides are believed to act by disrupting the plasma membrane leading to the lysis of the cell. AMPs have been found to be excellent candidates for developing novel antimicrobial agents and a few of these peptides show antimicrobial activity against pathogens causing sexually transmitted infection (STI), including HIV/HSV. Peptides, namely magainin and nisin have been shown to demonstrate contraceptive properties in vitro and in vivo. A few peptides have already entered clinical trials for the treatment of impetigo, diabetic foot ulcers and gastric helicobacter infections. In this review, we discuss the source, structures and mode of action with special reference to therapeutic considerations of various AMPs

  15. Group 11 Metal Compounds with Tripodal Bis(imidazole) Thioether Ligands. Applications as Catalysts in the Oxidation of Alkenes and as Antimicrobial Agents

    PubMed Central

    Liu, Fangwei; Anis, Reema; Hwang, Eunmi; Ovalle, Rafael; Varela-Ramírez, Armando; Aguilera, Renato J.; Contel, María

    2011-01-01

    displayed a very low cytotoxicity on this cell line (5 to 10 times lower than cisplatin) and on normal primary cells derived from C57B6 mouse muscle explants, which may make them promising candidates as potential antimicrobial agents and safer catalysts due to low toxicity in human and other mammalian tissues. PMID:25134773

  16. Antimicrobial Tolerance in Biofilms.

    PubMed

    Stewart, Philip S

    2015-06-01

    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

  17. 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

  18. Expression, purification and antimicrobial activity of puroindoline A protein and its mutants.

    PubMed

    Miao, Yingjie; Chen, Ling; Wang, Cheng; Wang, Yajuan; Zheng, Qian; Gao, Chunbao; Yang, Guangxiao; He, Guangyuan

    2012-10-01

    Wheat puroindoline proteins, PINA and PINB, play key roles in determining wheat grain hardness as well as in defending the plant against pathogens. PINA has much greater membrane-binding property and antimicrobial activity because it contains more tryptophan residues in the unique tryptophan-rich domain (TRD). In order to obtain proteins with higher antimicrobial activity, mutants of PINA containing two or three copies of TRD, designated ABBC and ABBBC, respectively, were constructed and expressed in E. coli Rosetta-gami (DE3). Metal affinity chromatography was used to purify the soluble affinity-tagged recombinant proteins. The secondary structures of the recombinant proteins were predicted by the online program Protein Homology/analog Y Recognition Engine v2.0 and experimentally assessed using circular dichroism. Minimum inhibition concentration tests and fluorescence microscope analyses were employed to evaluate the antimicrobial activities of the mutants. The results showed that the purified recombinant ABBC was correctly folded and presented significantly higher antimicrobial activities against E. coli and S. aureus than wild-type PINA, suggesting its potential use as an antimicrobial agent. The results also confirmed that TRD is a determinant of the antimicrobial activity of PINA and demonstrated that it is feasible to enhance the antimicrobial activity of PINA by adding one copy of TRD. PMID:22402594

  19. Ethephon As a Potential Abscission Agent for Table Grapes: Effects on Pre-Harvest Abscission, Fruit Quality, and Residue.

    PubMed

    Ferrara, Giuseppe; Mazzeo, Andrea; Matarrese, Angela M S; Pacucci, Carmela; Trani, Antonio; Fidelibus, Matthew W; Gambacorta, Giuseppe

    2016-01-01

    Some plant growth regulators, including ethephon, can stimulate abscission of mature grape berries. The stimulation of grape berry abscission reduces fruit detachment force (FDF) and promotes the development of a dry stem scar, both of which could facilitate the production of high quality stemless fresh-cut table grapes. The objective of this research was to determine how two potential abscission treatments, 1445 and 2890 mg/L ethephon, affected FDF, pre-harvest abscission, fruit quality, and ethephon residue of Thompson Seedless and Crimson Seedless grapes. Both ethephon treatments strongly induced abscission of Thompson Seedless berries causing >90% pre-harvest abscission. Lower ethephon rates, a shorter post-harvest interval, or berry retention systems such as nets, would be needed to prevent excessive pre-harvest losses. The treatments also slightly affected Thompson Seedless berry skin color, with treated fruit being darker, less uniform in color, and with a more yellow hue than non-treated fruit. Ethephon residues on Thompson Seedless grapes treated with the lower concentration of ethephon were below legal limits at harvest. Ethephon treatments also promoted abscission of Crimson Seedless berries, but pre-harvest abscission was much lower (≅49%) in Crimson Seedless compared to Thompson Seedless. Treated fruits were slightly darker than non-treated fruits, but ethephon did not affect SSC, acidity, or firmness of Crimson Seedless, and ethephon residues were below legal limits. PMID:27303407

  20. Ethephon As a Potential Abscission Agent for Table Grapes: Effects on Pre-Harvest Abscission, Fruit Quality, and Residue

    PubMed Central

    Ferrara, Giuseppe; Mazzeo, Andrea; Matarrese, Angela M. S.; Pacucci, Carmela; Trani, Antonio; Fidelibus, Matthew W.; Gambacorta, Giuseppe

    2016-01-01

    Some plant growth regulators, including ethephon, can stimulate abscission of mature grape berries. The stimulation of grape berry abscission reduces fruit detachment force (FDF) and promotes the development of a dry stem scar, both of which could facilitate the production of high quality stemless fresh-cut table grapes. The objective of this research was to determine how two potential abscission treatments, 1445 and 2890 mg/L ethephon, affected FDF, pre-harvest abscission, fruit quality, and ethephon residue of Thompson Seedless and Crimson Seedless grapes. Both ethephon treatments strongly induced abscission of Thompson Seedless berries causing >90% pre-harvest abscission. Lower ethephon rates, a shorter post-harvest interval, or berry retention systems such as nets, would be needed to prevent excessive pre-harvest losses. The treatments also slightly affected Thompson Seedless berry skin color, with treated fruit being darker, less uniform in color, and with a more yellow hue than non-treated fruit. Ethephon residues on Thompson Seedless grapes treated with the lower concentration of ethephon were below legal limits at harvest. Ethephon treatments also promoted abscission of Crimson Seedless berries, but pre-harvest abscission was much lower (≅49%) in Crimson Seedless compared to Thompson Seedless. Treated fruits were slightly darker than non-treated fruits, but ethephon did not affect SSC, acidity, or firmness of Crimson Seedless, and ethephon residues were below legal limits. PMID:27303407

  1. Evaluation of the in vitro activity of six broad-spectrum beta-lactam antimicrobial agents tested against recent clinical isolates from India: a survey of ten medical center laboratories.

    PubMed

    Mathai, Dilip; Rhomberg, Paul R; Biedenbach, Douglas J; Jones, Ronald N

    2002-12-01

    The widespread use of beta-lactam antimicrobial agents as first-line therapy for the treatment of serious infections has led to the development of various resistances that have compromised the use of some agents. In certain countries, the lack of local or national surveillance programs limits the ability to detect these resistant strains and prevent their dissemination. A 10 medical center study in India was initiated to benchmark prevailing resistance rates for a range of bacterial pathogens to beta-lactams, and it found high rates of beta-lactamase-mediated resistance in Escherichia coli and Klebsiella spp. These rates included: cephalosporins (55.6-61.3% resistance), with extended-spectrum beta-lactamase (ESBL) phenotypes noted in over 60% of E. coli isolates and in Salmonella spp. (3.2-8.1%). Imipenem, a carbapenem, was the only antimicrobial agent tested with 100% activity against Enterobacteriaceae. Cefpirome was the most active of the tested cephalosporins, and all were fully active against methicillin-susceptible staphylococci with the exception of ceftazidime. Molecular and susceptibility characterization of 52 selected ESBL-producing strains showed a high level of co-resistance with aminoglycosides and fluoroquinolones, and clonal dissemination of resistant strains within medical centers. Collaborative studies, such as those presented here, can accurately detect changes in resistance patterns, and their continued use may help limit the further development and spread of bacterial resistances in India. PMID:12543543

  2. Molecular characteristics and in vitro susceptibility to antimicrobial agents, including the des-fluoro(6) quinolone DX-619, of Panton-Valentine leucocidin-positive methicillin-resistant Staphylococcus aureus isolates from the community and hospitals.

    PubMed

    Yamamoto, Tatsuo; Dohmae, Soshi; Saito, Kohei; Otsuka, Taketo; Takano, Tomomi; Chiba, Megumi; Fujikawa, Katsuko; Tanaka, Mayumi

    2006-12-01

    Highly virulent, community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains with Panton-Valentine leucocidin (PVL) genes have been found increasingly worldwide. Among a total of 2,101 MRSA strains isolated from patients in hospitals in Japan, two were positive for PVL genes. One strain was identified as a community-acquired MRSA strain with genotype sequence type 30 (ST30) and spa (staphylococcal protein A gene) type 19 from Japan and was resistant only to beta-lactam antimicrobial agents. The other strain was closely related to PVL+ multidrug-resistant, hospital-acquired MRSA strains (ST30, spa type 43) derived from nosocomial outbreaks in the 1980s to 1990s in Japan but with a divergent sequence type, ST765 (a single-locus variant of ST30). Twenty-two PVL+ MRSA strains, including those from Japan and those from other countries with various sequence types (ST1, ST8, ST30, ST59, and ST80) and genotypes, were examined for susceptibility to 31 antimicrobial agents. Among the agents, DX-619, a des-fluoro(6) quinolone, showed the greatest activity, followed by rifampin and sitafloxacin, a fluoroquinolone. The data suggest that DX-619 exhibits a superior activity against PVL+ MRSA strains with various virulence genetic traits from the community as well as from hospitals. PMID:17043124

  3. [Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1998). III. Secular changes in susceptibility].

    PubMed

    Kumamoto, Y; Tsukamoto, T; Hirose, T; Matsukawa, M; Kunishima, Y; Matsuda, S; Sato, S; Ogiwara, M; Ishibashi, K; Fujime, M; Fujita, K; Shigeta, S; Watanabe, J; Igari, J; Yoshida, H; Imafuku, Y; Oguri, T; Murai, M; Yamaguchi, K; Matsumoto, T; Kashitani, F; Watanabe, K; Kobayashi, Y; Uchida, H; Ooe, H; Nishikawa, M; Kohno, S; Oka, T; Takano, Y; Miyagawa, Y; Miyazaki, Y; Izumikawa, K; Yamaguchi, T; Mochida, C; Furuhama, T

    2000-05-01

    Susceptibilities to various antimicrobial agents were examined for Enterococcus faecalis, Staphylococcus aureus, Echerichia coli, Klebsiella spp. and Pseudomonas aeruginosa that were isolated from patients with urinary tract infections (UTIs) in 9 hospitals during June 1998 to May 1999, and the results were compared with those obtained during the same period from 1990 to 1997 in uncomplicated UTIs and complicated UTIs. Among E. faecalis strains, those with low susceptibilities to almost drugs have increased in the latest period. All 5 S. aureus strains isolated from uncomplicated UTIs were the most susceptible to gentamicin (GM). Over 50% of S. aureus strains isolated from complicated UTIs were susceptible to GM, and on the contrary the resistant strains have increased with the MIC90 of 256 micrograms/ml or above. Among S. aureus strains isolated from complicated UTIs, those with low susceptibilities to arbekacin (ABK) have increased in the latest period compared to those during period of 1996-1997, and the MIC90s of them have changed into the lower state from 1 microgram/ml in 1996-1997 to 4 micrograms/ml in 1998. S. aureus strains have continued high susceptibilities to vancomycin (VCM). The susceptibilities to minocycline (MINO) of E. coli showed MIC90: 4 micrograms/ml in 1997, but those have returned in the latest period in uncomplicated UTIs. The MIC90s of ofloxacin (OFLX) to E. coli isolated from uncomplicated and complicated UTIs have been lower 2-3 classes in the latest period than those in 1997. Among Klebsiella spp. strains isolated from uncomplicated UTIs, those with low susceptibilities to almost cephems had increased in 1997, but few of them were detected in the latest study. The sensitive strains of P. aeruginosa to almost drugs have increased during the latest period. The MIC50s of cefozopran (CZOP) and OFLX against P. aeruginosa were the best in our history. The sensitive strains of P. aeruginosa to ceftazidime (CAZ) have increased and its

  4. Design and Evaluation of Novel Antimicrobial and Anticancer Agents Among Tetrazolo[1,5-c]quinazoline-5-thione S-Derivatives.

    PubMed

    Antypenko, Lyudmyla M; Kovalenko, Sergey I; Antypenko, Olexii M; Katsev, Andrey M; Achkasova, Olena M

    2013-03-01

    could be considered as a useful base for future development of potent antimicrobials and antitumor agents among tetrazolo[1,5-c]quinazoline-5-thione S-derivatives. PMID:23641327

  5. Resistance to Antimicrobial Peptides in Vibrios

    PubMed Central

    Destoumieux-Garzón, Delphine; Duperthuy, Marylise; Vanhove, Audrey Sophie; Schmitt, Paulina; Wai, Sun Nyunt

    2014-01-01

    Vibrios are associated with a broad diversity of hosts that produce antimicrobial peptides (AMPs) as part of their defense against microbial infections. In particular, vibrios colonize epithelia, which function as protective barriers and express AMPs as a first line of chemical defense against pathogens. Recent studies have shown they can also colonize phagocytes, key components of the animal immune system. Phagocytes infiltrate infected tissues and use AMPs to kill the phagocytosed microorganisms intracellularly, or deliver their antimicrobial content extracellularly to circumvent tissue infection. We review here the mechanisms by which vibrios have evolved the capacity to evade or resist the potent antimicrobial defenses of the immune cells or tissues they colonize. Among their strategies to resist killing by AMPs, primarily vibrios use membrane remodeling mechanisms. In particular, some highly resistant strains substitute hexaacylated Lipid A with a diglycine residue to reduce their negative surface charge, thereby lowering their electrostatic interactions with cationic AMPs. As a response to envelope stress, which can be induced by membrane-active agents including AMPs, vibrios also release outer membrane vesicles to create a protective membranous shield that traps extracellular AMPs and prevents interaction of the peptides with their own membranes. Finally, once AMPs have breached the bacterial membrane barriers, vibrios use RND efflux pumps, similar to those of other species, to transport AMPs out of their cytoplasmic space. PMID:27025756

  6. Synergistic activities of a silver(I) glutamic acid complex and reactive oxygen species (ROS): a novel antimicrobial and chemotherapeutic agent.

    PubMed

    Batarseh, K I; Smith, M A

    2012-01-01

    The antimicrobial and chemotherapeutic activities of a silver(I) glutamic acid complex with the synergistic concomitant generation of reactive oxygen species (ROS) were investigated here. The ROS generation system employed was via Fenton chemistry. The antimicrobial and chemotherapeutic activities were investigated on Staphylococcus aureus ATCC 43300 and Escherichia coli bacteria, and Vero and MCF-7 tumor cell lines, respectively. Antimicrobial activities were conducted by determining minimum inhibitory concentration (MIC), while chemotherapeutic efficacies were done by serial dilution using standard techniques to determine the half maximal inhibitory concentration (IC50). The antimicrobial and chemotherapeutic results obtained were compared with positive control drugs gentamicin, oxacillin, penicillin, streptomycin and cisplatin, a ubiquitously used platinum-based antitumor drug, and with the silver(I) glutamic acid complex and hydrogen peroxide separately. Based on MIC and IC50 values, it was determined that this synergistic approach was very effective at extremely low concentrations, especially when compared with the other drugs evaluated here. This finding might be of great significance regarding metronomic dosing when this synergistic approach is clinically implemented. Since silver at low concentrations exhibits no toxic, mutagenic and carcinogenic activities, this might offer an alternative approach for the development of safer silver-based antimicrobial and chemotherapeutic drugs, thereby reducing or even eliminating the toxicity associated with current drugs. Accordingly, the present approach might be integrated into the systemic clinical treatment of infectious diseases and cancer. PMID:22680634

  7. Introduction of sugammadex as standard reversal agent: Impact on the incidence of residual neuromuscular blockade and postoperative patient outcome

    PubMed Central

    Ledowski, Thomas; Hillyard, Samuel; O’Dea, Brendan; Archer, Rob; Vilas-Boas, Filipe; Kyle, Barney

    2013-01-01

    Background: The aim of this prospective audit was to investigate clinical practice related to muscle relaxant reversal and the impact made by the recent introduction of sugammadex on patient outcome at a tertiary teaching hospital. Methods: Data from all patients intubated at our institution during two epochs of seven consecutive days each was collected prospectively. Directly prior to extubation, the train-of-four (TOF) ratio was assessed quantitatively by an independent observer. Postoperative outcome parameters were complications in the recovery room and radiological diagnosed atelectasis or pneumonia within 30 days. Results: Data from 146 patients were analysed. Three reversal strategies were used: no reversal, neostigmine or sugammadex. The TOF ratio was less than 0.7 in 17 patients (nine no reversal, eight neostigmine) and less than 0.9 in 47 patients (24 no reversal, 19 neostigmine, four sugammadex). Those reversed with sugammadex showed fewer episodes of postoperative oxygen desaturation (15% vs. 33%; P<0.05). TOF ratios of less than 0.7 (P<0.05) and also <0.9 (P<0.01) were more likely associated with X-ray results consistent with postoperative atelectasis or pneumonia. Conclusions: Our results suggest a significant impact of residual paralysis on patient outcome. The use of sugammadex resulted in the lowest incidence of residual paralysis. PMID:23716766

  8. “Specificity Determinants” Improve Therapeutic Indices of Two Antimicrobial Peptides Piscidin 1 and Dermaseptin S4 against the Gram-negative Pathogens Acinetobacter baumannii and Pseudomonas aeruginosa

    PubMed Central

    Jiang, Ziqing; Vasil, Adriana I.; Vasil, Michael L.; Hodges, Robert S.

    2014-01-01

    A new class of antimicrobial agents with lower rates of resistance and different targets is urgently needed because of the rapidly increasing resistance to classical antibiotics. Amphipathic cationic α-helical antimicrobial peptides (AMPs) represent such a class of compounds. In our previous studies, using a 26-residue de novo designed antimicrobial peptide, we proposed the concept of “specificity determinant(s)”: positively charged residue(s) in the center of the non-polar face of AMPs that could decrease hemolytic activity/toxicity but increase or maintain the same level of antimicrobial activity to increase dramatically the therapeutic index. In the current study, we used d-enantiomers of two AMPs, Piscidin 1 isolated from fish and dermaseptin S4 isolated from frog. We substituted different positions in the center of the hydrophobic face with one or two lysine residue(s) (one or two “specificity determinant(s)”). This simple modification not only maintained or improved antimicrobial activity against Gram-negative pathogens Acinetobacter baumannii (11 strains) and Pseudomonas aeruginosa (6 strains), but also dramatically decreased hemolytic activity of human red blood cells, as predicted. Therapeutic indices improved by 55-fold and 730-fold for piscidin 1 (I9K) and dermaseptin S4 (L7K, A14K), respectively, against A. baumannii. Similarly, the therapeutic indices improved 32-fold and 980-fold for piscidin 1 (I9K) and dermaseptin S4 (L7K, A14K), respectively, against P. aeruginosa. PMID:24670666

  9. Synthesis and biological evaluation of (E)-1-(substituted)-3-phenylprop-2-en-1-ones bearing rhodanines as potent anti-microbial agents.

    PubMed

    Song, Ming-Xia; Deng, Xian-Qing; Li, Ya-Ru; Zheng, Chang-Ji; Hong, Lan; Piao, Hu-Ri

    2014-10-01

    Herein, we report the design, syntheses and in vitro anti-microbial activity of two series of rhodanines with chalcone moiety. Anti-microbial tests showed that some of the synthesized compounds exhibited good inhibition (MIC = 1-8 µg/mL) against multi-drug-resistant Gram-positive organisms, including methicillin resistant and quinolone-resistant Staphylococcus aureus, in which the compound 4g was found to be the most potent with minimum inhibitory concentration (MIC) value of 1 µg/mL against two methicillin-resistant S. aureus. PMID:24102526

  10. In vitro activities of 21 antimicrobial agents alone and in combination with aminoglycosides or fluoroquinolones against extended-spectrum-β-lactamase-producing Escherichia coli isolates causing bacteremia.

    PubMed

    Cha, Min Kyeong; Kang, Cheol-In; Kim, So Hyun; Cho, Sun Young; Ha, Young Eun; Wi, Yu Mi; Chung, Doo Ryeon; Peck, Kyong Ran; Song, Jae-Hoon

    2015-09-01

    We evaluated the in vitro activity of various antimicrobials alone and in combination against 291 extended-spectrum-β-lactamase-producing Escherichia coli (ESBL-EC) isolates causing bacteremia in South Korean hospitals. Ceftazidime, cefepime, and piperacillin-tazobactam in combination with amikacin showed greater activity than found in combination with ciprofloxacin. In settings with a high prevalence of ESBL-producing pathogens, combination aminoglycoside antimicrobial therapy, especially with amikacin, may be considered for empirical therapy against suspected Gram-negative sepsis as a carbapenem-saving strategy. PMID:26124174

  11. Antimicrobial activity of spherical silver nanoparticles prepared using a biocompatible macromolecular capping agent: evidence for induction of a greatly prolonged bacterial lag phase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have evaluated the antimicrobial properties of Ag-based nanoparticles (Np) using two solid platform-based bioassays and found that 10-20 uL of 0.3-3 uM keratin-based Nps (depending on the starting bacteria concentration = CI) completely inhibited the growth of an equivalent volume of ca. 1,000 to...

  12. 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

  13. Antimicrobials in periodontal maintenance.

    PubMed

    Jorgensen, M G; Slots, J

    2001-01-01

    Mechanical and chemical antimicrobial intervention is the mainstay of preventive periodontal therapy. Successful periodontal maintenance care depends upon the ability of oral health care professionals to combat periodontal infections, and patient compliance with prescribed follow-up care. Since tooth brushing, flossing, and oral rinsing do not reach pathogens present in furcations and at the depths of deep periodontal pockets, adequate oral hygiene should include subgingival treatment with home irrigators or other appropriate self-care remedies in patients with these conditions. Povidone-iodine for professional use and diluted bleach for self-care are inexpensive and valuable antimicrobial agents in periodontal maintenance. The present article outlines the prudent use of antimicrobial therapy in periodontal maintenance. PMID:11603305

  14. Development and validation of a stability-indicating gas chromatographic method for quality control of residual solvents in blonanserin: a novel atypical antipsychotic agent.

    PubMed

    Peng, Ming; Liu, Jin; Lu, Dan; Yang, Yong-Jian

    2012-09-01

    Blonanserin is a novel atypical antipsychotic agent for the treatment of schizophrenia. Ethyl alcohol, isopropyl alcohol and toluene are utilized in the synthesis route of this bulk drug. A new validated gas chromatographic (GC) method for the simultaneous determination of residual solvents in blonanserin is described in this paper. Blonanserin was dissolved in N, N-dimethylformamide to make a sample solution that was directly injected into a DB-624 column. A postrun oven temperature at 240°C for approximately 2 h after the analysis cycle was performed to wash out blonanserin residue in the GC column. Quantitation was performed by external standard analyses and the validation was carried out according to International Conference on Harmonization validation guidelines Q2A and Q2B. The method was shown to be specific (no interference in the blank solution), linear (correlation coefficients ≥0.99998, n = 10), accurate (average recoveries between 94.1 and 101.7%), precise (intra-day and inter-day precision ≤2.6%), sensitive (limit of detection ≤0.2 ng, and limit of quantitation ≤0.7 ng), robust (small variations of carrier gas flow, initial oven temperature, temperature ramping rate, injector and detector temperatures did not significantly affect the system suitability test parameters and peak areas) and stable (reference standard and sample solutions were stable over 48 h). This extensively validated method is ready to be used for the quality control of blonanserin. PMID:22595261

  15. Antimicrobial Peptides Design by Evolutionary Multiobjective Optimization

    PubMed Central

    Maccari, Giuseppe; Di Luca, Mariagrazia; Nifosí, Riccardo; Cardarelli, Francesco; Signore, Giovanni; Boccardi, Claudia; Bifone, Angelo

    2013-01-01

    Antimicrobial peptides (AMPs) are an abundant and wide class of molecules produced by many tissues and cell types in a variety of mammals, plant and animal species. Linear alpha-helical antimicrobial peptides are among the most widespread membrane-disruptive AMPs in nature, representing a particularly successful structural arrangement in innate defense. Recently, AMPs have received increasing attention as potential therapeutic agents, owing to their broad activity spectrum and their reduced tendency to induce resistance. The introduction of non-natural amino acids will be a key requisite in order to contrast host resistance and increase compound's life. In this work, the possibility to design novel AMP sequences with non-natural amino acids was achieved through a flexible computational approach, based on chemophysical profiles of peptide sequences. Quantitative structure-activity relationship (QSAR) descriptors were employed to code each peptide and train two statistical models in order to account for structural and functional properties of alpha-helical amphipathic AMPs. These models were then used as fitness functions for a multi-objective evolutional algorithm, together with a set of constraints for the design of a series of candidate AMPs. Two ab-initio natural peptides were synthesized and experimentally validated for antimicrobial activity, together with a series of control peptides. Furthermore, a well-known Cecropin-Mellitin alpha helical antimicrobial hybrid (CM18) was optimized by shortening its amino acid sequence while maintaining its activity and a peptide with non-natural amino acids was designed and tested, demonstrating the higher activity achievable with artificial residues. PMID:24039565

  16. Antimicrobial peptides

    PubMed Central

    2014-01-01

    With increasing antibiotics resistance, there is an urgent need for novel infection therapeutics. Since antimicrobial peptides provide opportunities for this, identification and optimization of such peptides have attracted much interest during recent years. Here, a brief overview of antimicrobial peptides is provided, with focus placed on how selected hydrophobic modifications of antimicrobial peptides can be employed to combat also more demanding pathogens, including multi-resistant strains, without conferring unacceptable toxicity. PMID:24758244

  17. Characterisation and cooperative antimicrobial properties of chitosan/nano-ZnO composite nanofibrous membranes.

    PubMed

    Wang, Yan; Zhang, Qun; Zhang, Chen-Lu; Li, Ping

    2012-05-01

    Chitosan was combined with nano-ZnO to increase its antimicrobial activity, using polyvinyl alcohol as a support, and then were electronspun to form composite nanofibres. Through SEM, EDX and XRD observations, chitosan was seen to be able to incorporate nano-ZnO in the composite nanofibres. Escherichia coli, expressing recombinant enhanced green fluorescent protein, and Candida albicans were used to test the antimicrobial efficacy of the newly synthesised chitosan/nano-ZnO antimicrobial composite. The CdTe quantum dots were used to rapidly detect the residual changes of C. albicans and determine the end point of using antimicrobial agents. Minimal minimum inhibitory concentration (MIC), post-antibiotic effect and continuous agent effect of the composite were determined. The MIC of chitosan/nano-ZnO against C. albicans was 160μg/ml, close to the concentration of the treated composite with the lowest fluorescence intensity. The cell damage was observed by SEM, which indicated that nano-ZnO in the nanofibrous membranes played a cooperative role in the antimicrobial process of chitosan. PMID:26434310

  18. The properties of antimicrobial films derived from poly(lactic acid)/starch/chitosan blended matrix.

    PubMed

    Bie, Pingping; Liu, Peng; Yu, Long; Li, Xiaoxi; Chen, Ling; Xie, Fengwei

    2013-10-15

    An antimicrobial material with a slow release property was developed based on poly(lactic acid)/starch/chitosan blends, in which chitosan acted as an antimicrobial agent while PLA and starch together were used as a slow-releasing device. An increase in the starch content drastically improved the hydrophilicity of the blends, which was favorable for the diffusion of the embedded chitosan. Moreover, the release of chitosan was observed to occur in two stages, with a very fast release stage initially and a slow but durable release stage as the latter. These two stages exhibited the effectiveness and long residual action of antimicrobial property of the blends respectively, demonstrating the suitability to be used for foods with high water activity, such as fresh meat. The tensile and thermal properties further verified the promising use of the blend material in packaging. PMID:23987434

  19. Dual evaluation of some novel 2-amino-substituted coumarinylthiazoles as anti-inflammatory-antimicrobial agents and their docking studies with COX-1/COX-2 active sites.

    PubMed

    Chandak, Navneet; Kumar, Pawan; Kaushik, Pawan; Varshney, Parul; Sharma, Chetan; Kaushik, Dhirender; Jain, Sudha; Aneja, Kamal R; Sharma, Pawan K

    2014-08-01

    Synthesis of total eighteen 2-amino-substituted 4-coumarinylthiazoles including sixteen new compounds (3a-o and 5b) bearing the benzenesulfonamide moiety is described in the present report. All the synthesized target compounds were examined for their in vivo anti-inflammatory (AI) activity and in vitro antimicrobial activity. Results revealed that six compounds (3 d, 3 f, 3 g, 3 h, 3 j and 3 n) exhibited pronounced anti-inflammatory activity comparable to the standard drug indomethacin. AI results were further confirmed by the docking studies of the most active (3n) and the least active compound (3a) with COX-1 and COX-2 active sites. In addition, most of the compounds exhibited moderate antimicrobial activity against Gram-positive bacteria as well as fungal yeast, S. cervisiae. Comparison between 3 and 5 indicated that incorporation of additional substituted pyrazole nucleus into the scaffold significantly enhanced AI activity. PMID:23777557

  20. Synthesis and biological screening of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyls as possible anti-tubercular and antimicrobial agents.

    PubMed

    Abhale, Yogita K; Sasane, Amit V; Chavan, Abhijit P; Deshmukh, Keshav K; Kotapalli, Sudha Sravanti; Ummanni, Ramesh; Sayyad, Sadikali F; Mhaske, Pravin C

    2015-04-13

    A series of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyl derivatives, 25-64 were synthesized and evaluated for inhibitory activity against Mycobacterium smegmatis MC(2) 155 strain and antimicrobial activities against four pathogenic bacteria Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Proteus vulgaris. Among them, compounds 40, 49, 50, and 54 exhibited moderate to good inhibition on the growth of the bacteria Mycobacterium smegmatis at the concentration of 30 μM. Compounds 26, 40, 44, 54 and 56 exhibited moderate to good antibacterial activity. Compound 5-(2'-(4-fluorobenzyl)thiazol-4'-yl)-2-(4-fluorophenyl)-4-methyl-thiazole (54) exhibited both antitubercular as well as antimicrobial activity against all tested strains. PMID:25778990

  1. Isolation and Identification of the Antimicrobial Agent Beauvericin from the Endophytic Fusarium oxysporum 5-19 with NMR and ESI-MS/MS

    PubMed Central

    Ruan, Chuanfen; Bai, Xuelian; Zhang, Miao; Zhu, Shuangshuang; Jiang, Yingying

    2016-01-01

    Endophytic microbe has been proved to be one of rich sources of bioactive natural products with potential application for new drug and pesticide discovery. One cyclodepsipeptide, beauvericin, was firstly isolated from the fermentation broth of Fusarium oxysporum 5-19 endophytic on Edgeworthia chrysantha Linn. Its chemical structure was unambiguously identified by a combination of spectroscopic methods, such as HRESI-MS and 1H and 13C NMR. ESI-MS/MS was successfully used to elucidate the splitting decomposition route of the positive molecule ion of beauvericin. Antimicrobial results showed that this cyclodepsipeptide had inhibitory effect on three human pathogenic microbes, Candida albicans, Escherichia coli, and Staphylococcus aureus. In particular, beauvericin exhibited the strongest antimicrobial activity against S. aureus with MIC values of 3.91 μM, which had similar effect with that of the positive control amoxicillin. PMID:27413733

  2. Isolation and Identification of the Antimicrobial Agent Beauvericin from the Endophytic Fusarium oxysporum 5-19 with NMR and ESI-MS/MS.

    PubMed

    Zhang, Huawei; Ruan, Chuanfen; Bai, Xuelian; Zhang, Miao; Zhu, Shuangshuang; Jiang, Yingying

    2016-01-01

    Endophytic microbe has been proved to be one of rich sources of bioactive natural products with potential application for new drug and pesticide discovery. One cyclodepsipeptide, beauvericin, was firstly isolated from the fermentation broth of Fusarium oxysporum 5-19 endophytic on Edgeworthia chrysantha Linn. Its chemical structure was unambiguously identified by a combination of spectroscopic methods, such as HRESI-MS and (1)H and (13)C NMR. ESI-MS/MS was successfully used to elucidate the splitting decomposition route of the positive molecule ion of beauvericin. Antimicrobial results showed that this cyclodepsipeptide had inhibitory effect on three human pathogenic microbes, Candida albicans, Escherichia coli, and Staphylococcus aureus. In particular, beauvericin exhibited the strongest antimicrobial activity against S. aureus with MIC values of 3.91 μM, which had similar effect with that of the positive control amoxicillin. PMID:27413733

  3. Trends in the susceptibility of commonly encountered clinically significant anaerobes and susceptibilities of blood isolates of anaerobes to 16 antimicrobial agents, including fidaxomicin and rifaximin, 2008-2012, northern Taiwan.

    PubMed

    Wang, F D; Liao, C H; Lin, Y T; Sheng, W H; Hsueh, P R

    2014-11-01

    We investigated the antimicrobial resistance trends and profiles of clinical anaerobic isolates in northern Taiwan. Trends in the susceptibility of five commonly encountered clinical anaerobic isolates to seven agents from 2008 to 2012 were measured using the Cochran-Armitage trend test. The minimum inhibitory concentrations (MICs) of 16 antimicrobial agents, including fidaxomicin and rifaximin, against anaerobic blood isolates from two medical centers were determined using the agar dilution method. During the study period, susceptibility data on 11,105 isolates were evaluated. Metronidazole and chloramphenicol retained excellent activities. Around 20-30 % of isolates of Bacteroides and Prevotella species were resistant to ampicillin-sulbactam, cefmetazole, flomoxef, and clindamycin. Of the 507 tested blood isolates, the rates of resistance to commonly used agents were much higher, namely, 16.2 % for amoxicillin-clavulanate, 15.6 % for ampicillin-sulbactam, 24.7 % for cefmetazole, and 36.1 % for clindamycin. Notably, 13.5 % of B. fragilis isolates were resistant to ertapenem. Also, 15.2 % of B. uniformis, 17.2 % of other Bacteroides species, 14.3 % of Prevotella species, and 14 % of Clostridium other than C. perfringens isolates were resistant to moxifloxacin. Cefoperazone-sulbactam was active against most isolates, except for Clostridium species other than perfringens (resistance rate, 18.6 %). Fidaxomicin exerted poor activities against most anaerobes tested (MIC90 of >128 μg/ml for B. fragilis and all isolates), except for C. perfringens (MIC90 of 0.03 μg/ml) and Peptostreptococcus micros (MIC90 of 2 μg/ml). However, rifaximin showed a wide range of susceptibilities against the tested anaerobes (MIC90 of 0.5 μg/ml for B. fragilis). The emergence of resistance to ertapenem and moxifloxacin among bacteremic anaerobes highlights the need for continuous monitoring. PMID:24930042

  4. Evaluation of certain veterinary drug residues in food. Fiftieth report of the joint FAO/WHO Expert Committee on Food Additives.

    PubMed

    1999-01-01

    This report presents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of residues of certain veterinary drugs in food and to recommend maximum levels for such residues. The first part of the report considers the neurotoxicity of anthelminthics belonging to the avermectin and milbemycin classes of compounds and the evaluation policy of the Committee in establishing Maximum Residue Levels (MRLs) for veterinary drugs in food. A summary follows of the Committee's evaluations of toxicological and residue data on a variety of veterinary drugs: five anthelminthic agents (eprinomectin, febantel, fenbendazole, oxfendazole and moxidectin), seven antimicrobial agents (gentamicin, procaine benzylpenicillin, sarafloxacin, spectinomycin, chlortetracycline, oxytetracycline and tetracycline), three antiprotozoal agents (diclazuril, imidocarb and nicarbazin), one glucocorticosteroid (dexamethasone), one production aid (recombinant bovine somatotropins) and one tranquilizing agent (azaperone). Annexed to the report are a summary of the Committee's recommendations on these drugs, including Acceptable Daily Intakes and MRLs, and further toxicological studies and other information required. PMID:10416362

  5. Antimicrobial stewardship

    PubMed Central

    Chung, Gladys W.; Wu, Jia En; Yeo, Chay Leng; Chan, Douglas; Hsu, Li Yang

    2013-01-01

    Antimicrobial stewardship is an emerging field currently defined by a series of strategies and interventions aimed toward improving appropriate prescription of antibiotics in humans in all healthcare settings. The ultimate goal is the preservation of current and future antibiotics against the threat of antimicrobial resistance, although improving patient safety and reducing healthcare costs are important concurrent aims. Prospective audit and feedback interventions are probably the most widely practiced of all antimicrobial stewardship strategies. Although labor-intensive, they are more easily accepted by physicians compared with formulary restriction and preauthorization strategies and have a higher potential for educational opportunities. Objective evaluation of antimicrobial stewardship is critical for determining the success of such programs. Nonetheless, there is controversy over which outcomes to measure and there is a pressing need for novel study designs that can objectively assess antimicrobial stewardship interventions despite the limitations inherent in the structure of most such programs. PMID:23302793

  6. Fate and transport of antimicrobials and antimicrobial resistance genes in soil and runoff following land application of swine slurry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the use of antimicrobials in livestock production, residual antimicrobials and antimicrobial resistance genes (ARGs) could enter the environment following the land application of animal wastes and could further contaminate surface and groundwater. The objective of this study was to determine ...

  7. 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.

  8. Complexes of Silver(I) Ions and Silver Phosphate Nanoparticles with Hyaluronic Acid and/or Chitosan as Promising Antimicrobial Agents for Vascular Grafts

    PubMed Central

    Chudobova, Dagmar; Nejdl, Lukas; Gumulec, Jaromir; Krystofova, Olga; Rodrigo, Miguel Angel Merlos; Kynicky, Jindrich; Ruttkay-Nedecky, Branislav; Kopel, Pavel; Babula, Petr; Adam, Vojtech; Kizek, Rene

    2013-01-01

    Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes

  9. In Vitro Activities of Ceftazidime-Avibactam, Aztreonam-Avibactam, and a Panel of Older and Contemporary Antimicrobial Agents against Carbapenemase-Producing Gram-Negative Bacilli

    PubMed Central

    Vasoo, Shawn; Cunningham, Scott A.; Cole, Nicolynn C.; Kohner, Peggy C.; Menon, Sanjay R.; Krause, Kevin M.; Harris, Kelly A.; De, Partha P.; Koh, Tse Hsien

    2015-01-01

    Among 177 carbapenemase-producing Gram-negative bacilli (108 KPC, 32 NDM, 11 IMP, 8 OXA-48, 4 OXA-181, 2 OXA-232, 5 IMI, 4 VIM, and 3 SME producers), aztreonam-avibactam was active against all isolates except two NDM producers with elevated MICs of 8/4 and 16/4 mg/liter; ceftazidime-avibactam was active against all KPC-, IMI-, SME-, and most OXA-48 group-producing isolates (93%) but not metallo-β-lactamase producers. Among older and contemporary antimicrobials, the most active were colistin, tigecycline, and fosfomycin, with overall susceptibilities of 88%, 79%, and 78%, respectively. PMID:26392487

  10. In Vitro Activities of Ceftazidime-Avibactam, Aztreonam-Avibactam, and a Panel of Older and Contemporary Antimicrobial Agents against Carbapenemase-Producing Gram-Negative Bacilli.

    PubMed

    Vasoo, Shawn; Cunningham, Scott A; Cole, Nicolynn C; Kohner, Peggy C; Menon, Sanjay R; Krause, Kevin M; Harris, Kelly A; De, Partha P; Koh, Tse Hsien; Patel, Robin

    2015-12-01

    Among 177 carbapenemase-producing Gram-negative bacilli (108 KPC, 32 NDM, 11 IMP, 8 OXA-48, 4 OXA-181, 2 OXA-232, 5 IMI, 4 VIM, and 3 SME producers), aztreonam-avibactam was active against all isolates except two NDM producers with elevated MICs of 8/4 and 16/4 mg/liter; ceftazidime-avibactam was active against all KPC-, IMI-, SME-, and most OXA-48 group-producing isolates (93%) but not metallo-β-lactamase producers. Among older and contemporary antimicrobials, the most active were colistin, tigecycline, and fosfomycin, with overall susceptibilities of 88%, 79%, and 78%, respectively. PMID:26392487

  11. 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

  12. Synthesis and antimicrobial studies of chalconyl pregnenolones.

    PubMed

    Banday, Abid H; Iqbal Zargar, M; Ganaie, Bashir A

    2011-11-01

    An efficient and facile synthesis of 17-chalconyl derivatives of pregnenolone and their evaluation as antimicrobial agents against various microbial strains is reported. The scheme involves the transformation of the starting pregnenolone acetate into pregnenolone, conversion of pregnenolone to the corresponding chalcone derivatives. The compounds 3a-3j showed significant antimicrobial activity against all microbial strains used for testing. PMID:21771607

  13. National Antimicrobial Resistance Monitoring System (NARMS) Program

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  14. Synthesis and antimicrobial activity of squalamine analogue.

    PubMed

    Kim, H S; Choi, B S; Kwon, K C; Lee, S O; Kwak, H J; Lee, C H

    2000-08-01

    Synthesis and antimicrobial activity of squalamine analogue 2 are reported. The synthesis of 2 was accomplished from bisnoralcohol 3. The spermidine moiety was introduced via reductive amination of an appropriately functionalized 3beta-aminosterol with spermidinyl aldehyde 17 utilizing sodium triacetoxyborohydride as the reducing agent. Compound 2 shows weaker antimicrobial activity than squalamine. PMID:11003150

  15. Evaluation of a method for assaying sulfonamide antimicrobial residues in cheese: hot-water extraction and liquid chromatography-tandem mass spectrometry.

    PubMed

    Berardi, Giorgio; Bogialli, Sara; Curini, Roberta; Di Corcia, Antonio; Laganá, Aldo

    2006-06-28

    Several sulfonamide antimicrobials (SAAs) are largely used in veterinary medicine. A rapid, specific, and sensitive procedure for determining 12 SAAs in cheese is presented. The method is based on the matrix solid-phase dispersion technique followed by liquid chromatography (LC)-tandem mass spectrometry (MS) equipped with an electrospray ion source. Target compounds were extracted from Mozzarella, Asiago, Parmigiano, Emmenthal, and Camembert cheese samples by 6 mL of water modified with 10% methanol and heated at 120 degrees C. The addition of methanol to hot water served to improve remarkably extraction yields of the most lipophilic SAAs, that is, sulfadimethoxine and sulfaquinoxaline. After acidification and filtration, 100 microL of the aqueous extract was injected in the LC column. MS data acquisition was performed in the multireaction monitoring mode, selecting two precursor-to-product ion transitions for each target compound. Methanol-modified hot water appeared to be an efficient extractant, because absolute recovery ranged between 67 and 88%. Using sulfamoxole as surrogate analyte, recovery of the 12 analytes spiked in the five types of cheese considered at the 50 ng/g level ranged between 75 and 105% with RSD not higher than 11%. Statistical analysis of the mean recovery data showed that the extraction efficiency was not affected by the type of cheese analyzed. This result indicates this method could be applied to other cheese types not considered here. The accuracy of the method was determined at three spike levels, that is, 20, 50, and 100 ng/g, and varied between 73 and 102% with relative standard deviations ranging between 4 and 12%. On the basis of a signal-to-noise ratio of 10, limits of quantification were estimated to be <1 ng/g. PMID:16786995

  16. [Search for antimicrobial agents and their various combinations that are effective in relation to the main microfloral representatives in the burn wound].

    PubMed

    Kataev, S V; Brodinova, N S; Moroz, A F

    1980-03-01

    Activity of 10 antibiotics, 6 surface active substances, 1 antioxidant and boric acid against P. aeruginosa, E. coli, Pr. vulgaris and Staph. aureus most frequently vegetating in burn wounds was studied. It was found that gentamicin had the highest antibacterial effect on the above organisms. Polymyxin M had a pronounced antimicrobial action on P. aeruginosa and E. coli. A significant antibacterial effect with respect to Staph. aureus, E. coli and Pr. vulgaris was observed with the use of the drugs of the nitrofuran line, i.e. salaful, furagin and furacillin. These drugs were not active against P. aeruginosa. A high antimicrobial effect with respect to all of the test-microbed used was recorded with methacyl, a surface active substance. To show the synergistic effect on the microbes most frequently vegetating in burn wounds, the antibacterial action of the drug combinations was studied. The synergistic effect (16 to 100 times) was observed with the use of polymyxin M combination with mafenide, carbenicillin with gentamicin, methacide with fenozan. The microorganisms tested were resistant to boric acid. On the basis of the study the most effective drugs and their combinations were chosen for their addition to the algipores (polymer coatings) used in treatment of burns infected with the above microbes. PMID:7362224

  17. Physicochemical, antimicrobial, and cytotoxic characteristics of a chitosan film cross-linked by a naturally occurring cross-linking agent, aglycone geniposidic acid.

    PubMed

    Mi, Fwu-Long; Huang, Chin-Tsung; Liang, Hsiang-Fa; Chen, Mei-Chin; Chiu, Ya-Ling; Chen, Chun-Hung; Sung, Hsing-Wen

    2006-05-01

    The purpose of this study was to evaluate the characteristics of a chitosan film cross-linked by a naturally occurring compound, aglycone geniposidic acid (aGSA). This newly developed aGSA-cross-linked chitosan film may be used as an edible film. The chitosan film without cross-linking (fresh) and the glutaraldehyde-cross-linked chitosan film were used as controls. The characteristics of test chitosan films evaluated were their degree of cross-linking, swelling ratio, mechanical properties, water vapor permeability, antimicrobial capability, cytotoxicity, and enzymatic degradability. It was found that cross-linking of chitosan films by aGSA (at a concentration up to 0.8 mM) significantly increased its ultimate tensile strength but reduced its strain at fracture and swelling ratio. There was no significant difference in the antimicrobial capability between the cross-linked chitosan films and their fresh counterpart. However, the aGSA-cross-linked chitosan film had a lower cytotoxicity, a slower degradation rate, and a relatively lower water vapor permeability as compared to the glutaraldehyde-cross-linked film. These results suggested that the aGSA-cross-linked chitosan film may be a promising material as an edible film. PMID:16637687

  18. D-amino acid peptide residualizing agents bearing N-hydroxysuccinimido-and maleimido- functional groups and their application for trastuzumab radioiodination

    PubMed Central

    Pruszynski, Marek; Koumarianou, Eftychia; Vaidyanathan, Ganesan; Chitneni, Satish; Zalutsky, Michael R.

    2014-01-01

    Introduction Proteins that undergo receptor-mediated endocytosis are subject to lysosomal degradation, requiring radioiodination methods that minimize loss of radioactivity from tumor cells after this process occurs. To accomplish this, we developed the residualizing radioiodination agent N∊-(3-[*I]iodobenzoyl)-Lys5-Nα-maleimido-Gly1-d-GEEEK (Mal-d-GEEEK-[*I]IB), which enhanced tumor uptake but also increased kidney activity and necessitates generation of sulfhydryl moieties on the protein. The purpose of the current study was to synthesize and evaluate a new d-amino acid based agent that might avoid these potential problems. Methods Nα-(3-iodobenzoyl)-(5-succinimidyloxycarbonyl)-d-EEEG (NHS-IB-d-EEEG), which contains 3 d-glutamates to provide negative charge and a N-hydroxysuccinimide function to permit conjugation to unmodified proteins, and the corresponding tin precursor were produced by solid phase peptide synthesis and subsequent conjugation with appropriate reagents. Radioiodination of the anti-HER2 antibody trastuzumab using NHS-IB-d-EEEG and Mal-d-GEEEK-IB were compared. Paired-label internalization assays on BT474 breast carcinoma cells and biodistribution studies in athymic mice bearing BT474M1 xenografts were performed to evaluate the two radioiodinated d-peptide trastuzumab conjugates. Results NHS-[131I]IB-d-EEEG was produced in 53.8 ± 13.4 % and conjugated to trastuzumab in 39.5 ± 7.6 % yield. Paired-label internalization assays with trastuzumab-NHS-[131I]IB-d-EEEG and trastuzumab-Mal-d-GEEEK-[125I]IB demonstrated similar intracellular trapping for both conjugates at 1 h (131I, 84.4 ± 6.1%; 125I, 88.6 ± 5.2%) through 24 h (131I, 60.7 ± 6.8%; 125I, 64.9 ± 6.9 %). In the biodistribution experiment, tumor uptake peaked at 48 h (trastuzumab-NHS-[131I]IB-d-EEEG, 29.8 ± 3.6 %ID/g; trastuzumab-Mal-d-GEEEK-[125I]IB, 45.3 ± 5.3 %ID/g) and was significantly higher for 125I at all time points. In general, normal tissue levels were lower for

  19. Antimicrobial Resistance

    MedlinePlus

    ... antibiotic are known as methicillin-resistant S. aureus or MRSA. Antibiotics and other antimicrobial drugs first became widely ... factors for infection are known as community-associated MRSA (CA-MRSA). Recently, several cases overseas and in ...

  20. Antimicrobial implications of vitamin D

    PubMed Central

    Youssef, Dima A; Miller, Christopher WT; El-Abbassi, Adel M; Cutchins, Della C; Cutchins, Coleman; Grant, William B

    2011-01-01

    Evidence exists that vitamin D has a potential antimicrobial activity and its deficiency has deleterious effects on general well-being and longevity. Vitamin D may reduce the risk of infection through multiple mechanisms. Vitamin D boosts innate immunity by modulating production of anti-microbial peptides (AMPs) and cytokine response. Vitamin D and its analogues via these mechanisms are playing an increasing role in the management of atopic dermatitis, psoriasis, vitiligo, acne and rosacea. Vitamin D may reduce susceptibility to infection in patients with atopic dermatitis and the ability to regulate local immune and inflammatory responses offers exciting potential for understanding and treating chronic inflammatory dermatitides. Moreover, B and T cell activation as well as boosting the activity of monocytes and macrophages also contribute to a potent systemic anti-microbial effect. The direct invasion by pathogenic organisms may be minimized at sites such as the respiratory tract by enhancing clearance of invading organisms. A vitamin D replete state appears to benefit most infections, with the possible noteworthy exception of Leishmaniasis. Antibiotics remain an expensive option and misuse of these agents results in significant antibiotic resistance and contributes to escalating health care costs. Vitamin D constitutes an inexpensive prophylactic option and possibly therapeutic product either by itself or as a synergistic agent to traditional antimicrobial agents. This review outlines the specific antimicrobial properties of vitamin D in combating a wide range of organisms. We discuss the possible mechanisms by which vitamin D may have a therapeutic role in managing a variety of infections. PMID:22259647

  1. Antimicrobial Resistance Mechanisms among Campylobacter

    PubMed Central

    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. PMID:23865047

  2. Antimicrobial activities of squalamine mimics.

    PubMed

    Kikuchi, K; Bernard, E M; Sadownik, A; Regen, S L; Armstrong, D

    1997-07-01

    We investigated the antimicrobial properties of compounds with structural features that were designed to mimic those of squalamine, an antibiotic isolated from the stomach of the dogfish shark. The mimics, like squalamine, are sterol-polyamine conjugates. Unlike squalamine, the mimics were simple to prepare, at high yield, from readily available starting materials. Several squalamine mimics showed activity against gram-negative rods, gram-positive cocci including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and fungi. Some had little or no hemolytic activity. The hydrophobicity of the sterol backbone and the length and the cationic charge of the side chains appeared to be critical determinants of activity. One of the squalamine mimics, SM-7, was bactericidal against Escherichia coli, Pseudomonas aeruginosa, and S. aureus; its activity was decreased by divalent or monovalent cations and by bovine serum albumin. Subinhibitory concentrations of SM-7 markedly enhanced the antimicrobial activity of rifampin against gram-negative rods. These results suggest that the compounds may disrupt an outer membrane of gram-negative rods. Squalamine mimics are a new class of broad-spectrum antimicrobial agents. The antagonism of their activity by serum and albumin and their hemolytic properties may limit their use as systemic agents. The squalamine mimics, because of their potencies, broad spectra of antimicrobial activity, and potential for systemic toxicity, appear to be good candidates for development as topical antimicrobial agents. PMID:9210661

  3. Antimicrobials therapy of anaerobic infections.

    PubMed

    Brook, Itzhak

    2016-06-01

    Anaerobes predominant in the normal human skin and mucous membranes bacterial flora are often a cause of endogenous infections. Anaerobic bacteria are difficult to isolate from infectious sites, and are often overlooked. Anaerobic infections caused by anaerobes can occur in all body sites, including the central nervous system (CNS), oral cavity, head and neck, chest, abdomen, pelvis, skin and soft tissues. The treatment of these infections is complicated by the slow growth of these organisms, their polymicrobial nature and the growing resistance of anaerobes to antimicrobials agents. Antimicrobials are frequently the only form of therapy needed, but in others, they are an important adjunct to surgical drainage and correction of pathology. Because anaerobes are often recovered with aerobic and facultative bacteria, the chosen antimicrobials should cover all pathogens. The antimicrobials effective against anaerobic organisms are metronidazole, carbapenems, combinations of a beta-lactam and a beta-lactamase inhibitor, chloramphenicol, tigecycline and clindamycin. PMID:26365224

  4. The First Salamander Defensin Antimicrobial Peptide

    PubMed Central

    Jiang, Ke; Rong, Mingqiang; Lai, Ren

    2013-01-01

    Antimicrobial peptides have been widely identified from amphibian skins except salamanders. A novel antimicrobial peptide (CFBD) was isolated and characterized from skin secretions of the salamander, Cynops fudingensis. The cDNA encoding CFBD precursor was cloned from the skin cDNA library of C. fudingensis. The precursor was composed of three domains: signal peptide of 17 residues, mature peptide of 41 residues and intervening propeptide of 3 residues. There are six cysteines in the sequence of mature CFBD peptide, which possibly form three disulfide-bridges. CFBD showed antimicrobial activities against Staphylococcus aureus, Bacillus subtilis, Candida albicans and Escherichia coli. This peptide could be classified into family of β-defensin based on its seqeuence similarity with β-defensins from other vertebrates. Evolution analysis indicated that CFBD was close to fish β-defensin. As far as we know, CFBD is the first β-defensin antimicrobial peptide from salamanders. PMID:24386139

  5. Synthesis and biological evaluation of novel N-substituted 1H-dibenzo[a,c]carbazole derivatives of dehydroabietic acid as potential antimicrobial agents.

    PubMed

    Gu, Wen; Qiao, Chao; Wang, Shi-Fa; Hao, Yun; Miao, Ting-Ting

    2014-01-01

    A series of new N-substituted 1H-dibenzo[a,c]carbazole derivatives were synthesized from dehydroabietic acid, and their structures were characterized by IR, (1)H NMR and HRMS spectral data. All compounds were evaluated for their antibacterial and antifungal activities against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens) and three fungi (Candida albicans, Candida tropicalis and Aspergillus niger) by serial dilution technique. Some of the synthesized compounds displayed pronounced antimicrobial activity against tested strains with low MIC values ranging from 0.9 to 15.6μg/ml. Among them, compounds 6j and 6r exhibited potent inhibitory activity comparable to reference drugs amikacin and ketoconazole. PMID:24300736

  6. Bio-synthesis of silver nanoparticles using Potentilla fulgens Wall. ex Hook. and its therapeutic evaluation as anticancer and antimicrobial agent.

    PubMed

    Mittal, Amit Kumar; Tripathy, Debabrata; Choudhary, Alka; Aili, Pavan Kumar; Chatterjee, Anupam; Singh, Inder Pal; Banerjee, Uttam Chand

    2015-08-01

    The present study aims to develop an easy and eco-friendly method for the synthesis of silver nanoparticles using extracts from the medicinal plant, Potentilla fulgens and evaluation of its anticancer and antimicrobial properties. The various parts of P. fulgens were screened and the root extract was found to have the highest potential for the synthesis of nanoparticles. The root extracts were able to quickly reduce Ag(+) to Ag(0) and stabilized the nanoparticles. The synthesis of nanoparticles was confirmed by UV-Visible spectrophotometry and further characterized using Zeta sizer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Electron microscopic study showed that the size of the nanoparticle was in the range of 10 to 15 nm and spherical in shape. The studies of phytochemical analysis of nanoparticles indicated that the adsorbed components on the surface of nanoparticles were mainly flavonoid in nature. Furthermore, nanoparticles were evaluated as cytotoxic against various cancer cell lines and 0.2 to 12 μg/mL nanoparticles showed good toxicity. The IC50 value of nanoparticles was found to be 4.91 and 8.23 μg/mL against MCF-7 and U-87 cell lines, respectively. Additionally, the apoptotic effect of synthesized nanoparticles on normal and cancer cells was studied using trypan blue assay and flow-cytometric analysis. The results indicate the synthesized nanoparticle ability to kill cancer cells compared to normal cells. The nanoparticles also exhibited comparable antimicrobial activity against both Gram-positive and Gram-negative bacteria. PMID:26042698

  7. Antimicrobial susceptibility of Mycoplasma hyorhinis.

    PubMed

    Wu, C C; Shryock, T R; Lin, T L; Faderan, M; Veenhuizen, M F

    2000-09-15

    A broth microdilution technique was used to determine the antimicrobial susceptibility of 15 field isolates of Mycoplasma hyorhinis to 10 antimicrobial agents, representative of different classes, and contrasting newer agents to existing ones. For the macrolides, the MIC(90) for tylosin and tilmicosin was 1 and 4 microg/ml, respectively, but was > or = 16 microg/ml for erythromycin. Tetracycline, lincomycin and enrofloxacin each had an MIC(90) of 2 microg/ml. The mycoplasma had similar levels of susceptibility to the aminoglycoside and aminocyclictol classes exhibiting an MIC(90) of 4 microg/ml for gentamicin and 2 microg/ml for spectinomycin. The isolates exhibited high MICs to trimethoprim/sulfamethoxazole with an MIC(90) > or = 16/304 microg/ml. In summary, M. hyorhinis isolates from the US had low MICs against a variety of antimicrobials tested, with the exception of erythromycin and trimethoprim/sulfamethoxazole. PMID:10925038

  8. Superior in vitro activity of carbapenems over anti-methicillin-resistant Staphylococcus aureus (MRSA) and some related antimicrobial agents for community-acquired MRSA but not for hospital-acquired MRSA.

    PubMed

    Takano, Tomomi; Higuchi, Wataru; Yamamoto, Tatsuo

    2009-02-01

    Eighty-eight strains of Panton-Valentine leukocidin (PVL)-positive and -negative community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) and 152 strains of hospital-acquired MRSA (HA-MRSA) were examined for susceptibility to carbapenems, oxacillin, and other antimicrobial agents. CA-MRSA strains were more susceptible to carbapenems (MIC(90), 1-4 microg/ml) than HA-MRSA strains (MIC(90), 32-64 microg/ml). Among the carbapenems examined, CA-MRSA strains were most susceptible to imipenem (MIC(50), 0.12 microg/ml; MIC(90), 1 microg/ml). A similar tendency was observed with oxacillin, but less markedly (MIC(90): 32 microg/ml for CA-MRSA and > or =256 microg/ml for HA-MRSA). This difference was also observed between CA-MRSA and HA-MRSA in susceptibility levels to cephems, erythromycin, clindamycin, and levofloxacin, but not to ampicillin, vancomycin, teicoplanin, linezolid, and arbekacin. The data indicate that, in terms of MIC(50) or MIC(90) values, CA-MRSA is 64-256 times more susceptible to imipenem than HA-MRSA, and for CA-MRSA, some carbapenems, e.g., imipenem, show better in vitro activity than anti-MRSA or some related agents. PMID:19280303

  9. Identification of antimicrobial peptides from teleosts and anurans in expressed sequence tag databases using conserved signal sequences.

    PubMed

    Tessera, Valentina; Guida, Filomena; Juretić, Davor; Tossi, Alessandro

    2012-03-01

    The problem of multidrug resistance requires the efficient and accurate identification of new classes of antimicrobial agents. Endogenous antimicrobial peptides produced by most organisms are a promising source of such molecules. We have exploited the high conservation of signal sequences in teleost and anuran antimicrobial peptides to search cDNA (expressed sequence tag) databases for likely candidates. Subject sequences were then analysed for the presence of potential antimicrobial peptides based on physicochemical properties (amphipathic helical structure, cationicity) and use of the D-descriptor model to predict the therapeutic index (relation between the minimum inhibitory concentration and the concentration giving 50% haemolysis). This analysis also suggested mutations to probe the role of the primary structure in determining potency and selectivity. Selected sequences were chemically synthesized and the antimicrobial activity of the peptides was confirmed. In particular, a short (21-residue) sequence, likely of sticklefish origin, showed potent activity and it was possible to tune the spectrum of action and/or selectivity by combining three directed mutations. Membrane permeabilization studies on both bacterial and host cells indicate that the mode of action was prevalently membranolytic. This method opens up the possibility for more effective searching of the vast and continuously growing expressed sequence tag databases for novel antimicrobial peptides, which are likely abundant, and the efficient identification of the most promising candidates among them. PMID:22188679

  10. Application of natural antimicrobials for food preservation.

    PubMed

    Tiwari, Brijesh K; Valdramidis, Vasilis P; O'Donnell, Colm P; Muthukumarappan, Kasiviswanathan; Bourke, Paula; Cullen, P J

    2009-07-22

    In this review, antimicrobials from a range of plant, animal, and microbial sources are reviewed along with their potential applications in food systems. Chemical and biochemical antimicrobial compounds derived from these natural sources and their activity against a range of pathogenic and spoilage microorganisms pertinent to food, together with their effects on food organoleptic properties, are outlined. Factors influencing the antimicrobial activity of such agents are discussed including extraction methods, molecular weight, and agent origin. These issues are considered in conjunction with the latest developments in the quantification of the minimum inhibitory (and noninhibitory) concentration of antimicrobials and/or their components. Natural antimicrobials can be used alone or in combination with other novel preservation technologies to facilitate the replacement of traditional approaches. Research priorities and future trends focusing on the impact of product formulation, intrinsic product parameters, and extrinsic storage parameters on the design of efficient food preservation systems are also presented. PMID:19548681

  11. Antimicrobial use and antimicrobial resistance in nosocomial pathogens at a tertiary care hospital in Pune

    PubMed Central

    Nair, Velu; Sharma, Dinesh; Sahni, A.K.; Grover, Naveen; Shankar, S.; Jaiswal, S.S.; Dalal, S.S.; Basannar, D.R.; Phutane, Vivek S.; Kotwal, Atul; Gopal Rao, G.; Batura, Deepak; Venkatesh, M.D.; Sinha, Tapan; Kumar, Sushil; Joshi, D.P.

    2015-01-01

    Background Resistance to antimicrobial agents is emerging in wide variety of nosocomial and community acquired pathogens. Widespread and often inappropriate use of broad spectrum antimicrobial agents is recognized as a significant contributing factor to the development and spread of bacterial resistance. This study was conducted to gain insight into the prevalent antimicrobial prescribing practices, and antimicrobial resistance pattern in nosocomial pathogens at a tertiary care hospital in Pune, India. Methods Series of one day cross sectional point prevalence surveys were carried out on four days between March and August 2014. All eligible in patients were included in the study. A structured data entry form was used to collect the data for each patient. Relevant samples were collected for microbiological examination from all the clinically identified hospital acquired infection cases. Results 41.73% of the eligible patients (95% CI: 39.52–43.97) had been prescribed at least one antimicrobial during their stay in the hospital. Beta-lactams (38%) were the most prescribed antimicrobials, followed by Protein synthesis inhibitors (24%). Majority of the organisms isolated from Hospital acquired infection (HAI cases) were found to be resistant to the commonly used antimicrobials viz: Cefotaxime, Ceftriaxone, Amikacin, Gentamicin and Monobactams. Conclusion There is need to have regular antimicrobial susceptibility surveillance and dissemination of this information to the clinicians. In addition, emphasis on the rational use of antimicrobials, antimicrobial rotation and strict adherence to the standard treatment guidelines is very essential. PMID:25859071

  12. Synthesis of 2-{(5-phenyl-1,3,4-Oxadiazol-2-yl)sulfanyl}-N-substituted acetamides as potential antimicrobial and hemolytic agents.

    PubMed

    Rehman, Aziz-ur; Abbasi, Muhammad Athar; Siddiqui, Sabahat Zahra; Ahmad, Irshad; Shahid, Muhammad; Subhani, Zinayyera

    2016-05-01

    A new series of N-substituted derivatives of 2-{(5-phenyl-1,3,4-Oxadiazol-2-yl)sulfanyl}acetamides was synthesized. The synthesis was carried out by converting benzoic acid (1) into ethyl benzoate (2), benzohydrazide (3) and then 5-pheny-1,3,4-Oxadiazol-2-thiol (4) step by st0ep. The target compounds 6a-p were synthesized by reaction of compound 4 with equimolar ratios of different N-alkyl/aryl substituted 2-bromoacetamide (5a-p) in the presence of DMF and sodium hydride (NaH). The spectral (EI-MS, IR, (1)H-NMR) characterization of all the synthesized compounds reveal their successful synthesis. The compounds were also screened for antimicrobial & hemolytic activity and most of them were found to be active against the selected microbial species at variable extent relative to reference standards. But 6h was the most active against the selected panel of microbes. This series showed less toxicity and may be considered for further biological screening and application trial except 6m, possessing higher cytotoxicity. PMID:27166551

  13. One-pot three-component domino protocol for the synthesis of novel pyrano[2,3-d]pyrimidines as antimicrobial and anti-biofilm agents.

    PubMed

    Suresh, Lingala; Poornachandra, Y; Kanakaraju, S; Ganesh Kumar, C; Chandramouli, G V P

    2015-07-14

    A simple and facile synthesis of a series of novel pyrano[2,3-d]pyrimidines has been achieved successfully via the one-pot three-component reaction of 2-amino-7-methyl-5-oxo-4-phenyl-4,5-dihydropyrano[4,3-b]pyran-3-carbonitriles, DMF-DMA and arylamines in the presence of 1-butyl-3-methylhydrogensulphate [Bmim]HSO4 ionic liquid. This method has several advantages such as high yields, clean reaction, simple methodology and short reaction times. The synthesized compounds were evaluated for their antimicrobial activity against Gram-positive, Gram-negative and different Candida strains. Among the derivatives screened, compounds 4c, 4d, 4h and 4l were found to be active against both bacterial and Candida strains with MIC values ranging from 3.9 to 31.2 μg mL(-1). In addition, compound 4l showed a good minimum bactericidal concentration, minimum fungicidal concentration and anti-biofilm activities. Furthermore, the mode of the antifungal action for the promising compound 4l was evaluated in C. albicans MTCC 1637 through an ergosterol biosynthesis inhibition process. PMID:26054925

  14. Zinc and copper in animal feed – development of resistance and co-resistance to antimicrobial agents in bacteria of animal origin

    PubMed Central

    Yazdankhah, Siamak; Rudi, Knut; Bernhoft, Aksel

    2014-01-01

    Farmed animals such as pig and poultry receive additional Zn and Cu in their diets due to supplementing elements in compound feed as well as medical remedies. Enteral bacteria in farmed animals are shown to develop resistance to trace elements such as Zn and Cu. Resistance to Zn is often linked with resistance to methicillin in staphylococci, and Zn supplementation to animal feed may increase the proportion of multiresistant E. coli in the gut. Resistance to Cu in bacteria, in particular enterococci, is often associated with resistance to antimicrobial drugs like macrolides and glycopeptides (e.g. vancomycin). Such resistant bacteria may be transferred from the food-producing animals to humans (farmers, veterinarians, and consumers). Data on dose-response relation for Zn/Cu exposure and resistance are lacking; however, it seems more likely that a resistance-driven effect occurs at high trace element exposure than at more basal exposure levels. There is also lack of data which could demonstrate whether Zn/Cu-resistant bacteria may acquire antibiotic resistance genes/become antibiotics resistant, or if antibiotics-resistant bacteria are more capable to become Zn/Cu resistant than antibiotics-susceptible bacteria. Further research is needed to elucidate the link between Zn/Cu and antibiotic resistance in bacteria. PMID:25317117

  15. Antimicrobial susceptibility pattern of Helicobacter suis strains.

    PubMed

    Vermoote, Miet; Pasmans, Frank; Flahou, Bram; Van Deun, Kim; Ducatelle, Richard; Haesebrouck, Freddy

    2011-12-15

    Helicobacter suis is a very fastidious porcine gastric pathogen, which is also considered to be of zoonotic importance. In vitro antimicrobial susceptibility cannot be determined using standard assays, as this agent only grows in a biphasic medium with an acidic pH. Therefore, a combined agar and broth dilution method was used to analyse the activity of nine antimicrobial agents against nine H. suis isolates. After 48 h microaerobic incubation, minimal inhibitory concentrations (MICs) were determined by software-assisted calculation of bacterial growth. Only for enrofloxacin a bimodal distribution of MICs was demonstrated, indicating acquired resistance in one strain, which showed an AGT→AGG (Ser→Arg) substitution at codon 99 of gyrA. In conclusion, the assay developed here is suitable for determination of the antimicrobial susceptibility of H. suis isolates, although activity of acid sensitive antimicrobial agents may be higher than predicted from MIC endpoints. PMID:21733643

  16. The effect of thiol functional group incorporation into cationic helical peptides on antimicrobial activities and spectra.

    PubMed

    Wiradharma, Nikken; Khan, Majad; Yong, Lin-Kin; Hauser, Charlotte A E; Seow, See Voon; Zhang, Shuguang; Yang, Yi-Yan

    2011-12-01

    Antimicrobial peptides (AMP) have been proposed as blueprints for the development of new antimicrobial agents for the treatment of drug resistant infections. A series of synthetic AMPs capable of forming α-helical structures and containing free-sulfhydryl groups are designed in this study ((LLKK)(2)C, C(LLKK)(2)C, (LLKK)(3)C, C(LLKK)(3)C). In particular, the AMP with 2 cysteine residues at the terminal ends of the peptide and 2 repeat units of LLKK, i.e., C(LLKK)(2)C, has been demonstrated to have high selectivity towards a wide range of microbes from Gram-positive Bacillus subtilis, Gram-negative Escherichia coli, Pseudomonas aerogenosa, and yeast Candida albicans over red blood cells. At the MIC levels, this peptide does not induce significant hemolysis, and its MIC values occur at the concentration of more than 10 times of their corresponding 50% hemolysis concentrations (HC(50)). Microscopy studies suggest that this peptide kills microbial cells by inducing pores of ∼20-30 nm in size in microbial membrane on a short time scale, which further develops to grossly damaged membrane envelope on a longer time scale. Multiple treatments of microbes with this peptide at sub MIC concentration do not induce resistance, even up to passage 10. However, the same treatment with conventional antibiotics penicillin G or ciprofloxacin easily develop resistance in the treated microbes. In addition, the peptides are shown not to induce secretion of IFN-γ and TNF-α in human monocytes as compared to lipopolysaccharide, which implies additional safety aspects of the peptides to be used as both systemic and topical antimicrobial agents. Therefore, this study provides an excellent basis to develop promising antimicrobial agents that possess a broad range of antimicrobial activities with less susceptibility for development of drug resistance. PMID:21906803

  17. The inhibition of Pseudomonas aeruginosa biofilm formation by micafungin and the enhancement of antimicrobial agent effectiveness in BALB/c mice.

    PubMed

    Kissoyan, Kohar Annie B; Bazzi, Wael; Hadi, Usamah; Matar, Ghassan M

    2016-08-01

    Micafungin inhibits biofilm formation by impeding 1,3-β-D-glucan synthesis in Candida albicans. Since Pseudomonas aeruginosa also has 1,3-β-D-glucan in its cell wall, this study assessed the effects of antibacterial agents in vitro and in vivo on micafungin-treated biofilm-forming P. aeruginosa isolates. After treatment with micafungin as well as with a panel of four antibacterial agents, biofilm production was significantly reduced as measured by spectrophotometry. The relative mRNA transcription levels for the genes encoding pellicles (pelC) and cell wall 1,3-β-D-glucan (ndvB), which were measured by quantitative reverse transcription PCR (qRT-PCR), significantly decreased with micafungin treatment. In vivo, the survival rates of P. aeruginosa-infected BALB/c mice significantly increased after combined treatment with micafungin and each of the antibacterial agents. Of these treatments, the combination of micafungin with levofloxacin had the highest survival rate; this combination was the most effective treatment against P. aeruginosa-induced infection. PMID:27347641

  18. Synthesis and structure-activity relationship of novel 1,4-diazabicyclo[2.2.2]octane derivatives as potent antimicrobial agents.

    PubMed

    Yarinich, Lyubov A; Burakova, Ekaterina A; Zakharov, Boris A; Boldyreva, Elena V; Babkina, Irina N; Tikunova, Nina V; Silnikov, Vladimir N

    2015-05-01

    A series of new quaternary 1,4-diazabicyclo[2.2.2]octane derivatives was synthesized and evaluated for activity against several strains of both Gram positive and Gram negative bacteria and one strain of fungus under different inoculum size. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against six species of microorganisms were tested. Results show a clear structure-activity relationship between alkyl chain length of substitutions of 1,4-diazabicyclo[2.2.2]octane tertiary amine sites and antimicrobial activity. In the case of compounds 4a-4k, MIC was found to decrease with the increase of the alkyl chain length from ethyl to dodecyl and then to increase at higher chain length (n > 14). The MIC values were found to be low for the compounds 4f and 4g with alkyl chains ranging from 10 to 12 carbons in length (1.6 μg/ml) and were comparable to the reference drug Ciprofloxacin. Also, time-kill assay was performed to examine the bactericidal kinetics. Results indicated that 4f and 4g had rapid killing effects against Staphylococcus aureus, and eliminated 100% of the initial inoculum of bacteria in 2.5 h at the concentration of 10 μg/ml. In addition, compound 4g eliminate more than 99.9% of the initial inoculum of Ps. aeruginosa after 2.5 h of interaction but the activity of compound 4f against this species seems to be weak. Thus, 4g had strong bactericidal activity and could rapidly kill Gram positive S. aureus, as well as Gram negative Ps. aeruginosa at low and high inoculum size. PMID:25867737

  19. Rapid 'one-pot' synthesis of a novel benzimidazole-5-carboxylate and its hydrazone derivatives as potential anti-inflammatory and antimicrobial agents.

    PubMed

    Vasantha, Kumar; Basavarajaswamy, Guru; Vaishali Rai, M; Boja, Poojary; Pai, Vinitha R; Shruthi, N; Bhat, Mahima

    2015-04-01

    A novel series of N-arylidene-2-(2,4-dichloro phenyl)-1-propyl-1H-benzo[d] imidazole-5-carbohydrazides having different substitution on the arylidene part were synthesized in good yield. The core nucleus benzimidazole-5-carboxylate (5) was efficiently synthesized by 'one-pot' nitro reductive cyclization reaction between ethyl-3-nitro-4-(propylamino)benzoate and 2,4-dichlorobenzaldehyde using sodium dithionite in dimethylsulfoxide. This 'one-pot' reaction was proceeded very smoothly, in short reaction time with an excellent yield. All the compounds (7a-r) were screened for their in vivo anti-inflammatory and in vitro antimicrobial activity. Most of the compounds exhibited remarkable paw-edema inhibition in the initial one hour of administration indicating the higher potentiality of these molecules. In particular, compounds 7a, 7d, 7f and 7g displayed a high level of carrageenan-induced paw edema inhibition compared to that of indomethacin. Compound 7p exhibited very good antibacterial activity and antifungal activity with a MIC of 3.12 μg/mL against most of the tested organisms. Furthermore, compounds 7d, 7f, 7h and 7p found to be good inhibitors of Aspergillus niger with MIC of 3.12 μg/mL. Cytotoxicity of the potent compounds 7d, 7f and 7p was checked using MDA MB-231 breast cancer cell line and are found to be non toxic at the highest concentration used (i.e., 10 μg/mL). PMID:25765910

  20. Comparative evaluation of silver-containing antimicrobial dressings and drugs.

    PubMed

    Castellano, Joseph J; Shafii, Susan M; Ko, Francis; Donate, Guillermo; Wright, Terry E; Mannari, Rudolph J; Payne, Wyatt G; Smith, David J; Robson, Martin C

    2007-06-01

    Wound dressings containing silver as antimicrobial agents are available in various forms and formulations; however, little is understood concerning their comparative efficacy as antimicrobial agents. Eight commercially available silver-containing dressings, Acticoat 7, Acticoat Moisture Control, Acticoat Absorbent, Silvercel, Aquacel Ag, Contreet F, Urgotol SSD and Actisorb, were tested to determine their comparative antimicrobial effectiveness in vitro and compared against three commercially available topical antimicrobial creams, a non treatment control, and a topical silver-containing antimicrobial gel, Silvasorb. Zone of inhibition and quantitative testing was performed by standard methods using Escherichia coli, Pseudomonas aeruginosa, Streptococcus faecalis and Staphylococcus aureus. Results showed all silver dressings and topical antimicrobials displayed antimicrobial activity. Silver-containing dressings with the highest concentrations of silver exhibited the strongest bacterial inhibitive properties. Concreet F and the Acticoat dressings tended to have greater antimicrobial activity than did the others. Topical antimicrobial creams, including silver sulfadiazine, Sulfamylon and gentamicin sulfate, and the topical antimicrobial gel Silvasorb exhibited superior bacterial inhibition and bactericidal properties, essentially eliminating all bacterial growth at 24 hours. Silver-containing dressings are likely to provide a barrier to and treatment for infection; however, their bactericidal and bacteriostatic properties are inferior to commonly used topical antimicrobial agents. PMID:17651227

  1. 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

  2. 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

  3. Application of gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry to the analysis of chemical warfare samples, found to contain residues of the nerve agent sarin, sulphur mustard and their degradation products.

    PubMed

    Black, R M; Clarke, R J; Read, R W; Reid, M T

    1994-02-25

    Samples of clothing, grave debris, soil and munition fragments, collected from the Kurdish village of Birjinni, were analysed by GC-MS with selected ion monitoring (SIM) for traces of chemical warfare agents and their degradation products. Positive analyses were confirmed, where possible, by full scan mass spectra, or at low concentrations by additional GC-MS-SIM analysis using chemical ionisation, by higher resolution GC-MS-SIM, and by GC-tandem mass spectrometry using multiple reaction monitoring. Sulphur mustard and/or thiodiglycol were detected in six soil samples; isopropyl methylphosphonic acid and methylphosphonic acid, the hydrolysis products of the nerve agent sarin, were detected in six different soil samples. Trace amounts of intact sarin were detected on a painted metal fragment associated with one of these soil samples. The results demonstrate the application of different GC-MS and GC-MS-MS techniques to the unequivocal identification of chemical warfare agent residues in the environment at concentrations ranging from low ppb to ppm (w/w). They also provide the first documented unequivocal identification of nerve agent residues in environmental samples collected after a chemical attack. PMID:8143028

  4. Antimicrobial agent triclosan is a proton ionophore uncoupler of mitochondria in living rat and human mast cells and in primary human keratinocytes.

    PubMed

    Weatherly, Lisa M; Shim, Juyoung; Hashmi, Hina N; Kennedy, Rachel H; Hess, Samuel T; Gosse, Julie A

    2016-06-01

    Triclosan (TCS) is an antimicrobial used widely in hospitals and personal care products, at ~10 mm. Human skin efficiently absorbs TCS. Mast cells are ubiquitous key players both in physiological processes and in disease, including asthma, cancer and autism. We previously showed that non-cytotoxic levels of TCS inhibit degranulation, the release of histamine and other mediators, from rat basophilic leukemia mast cells (RBL-2H3), and in this study, we replicate this finding in human mast cells (HMC-1.2). Our investigation into the molecular mechanisms underlying this effect led to the discovery that TCS disrupts adenosine triphosphate (ATP) production in RBL-2H3 cells in glucose-free, galactose-containing media (95% confidence interval EC50 = 7.5-9.7 µm), without causing cytotoxicity. Using these same glucose-free conditions, 15 µm TCS dampens RBL-2H3 degranulation by 40%. The same ATP disruption was found with human HMC-1.2 cells (EC50 4.2-13.7 µm), NIH-3 T3 mouse fibroblasts (EC50 4.8-7.4 µm) and primary human keratinocytes (EC50 3.0-4.1 µm) all with no cytotoxicity. TCS increases oxygen consumption rate in RBL-2H3 cells. Known mitochondrial uncouplers (e.g., carbonyl cyanide 3-chlorophenylhydrazone) previously were found to inhibit mast cell function. TCS-methyl, which has a methyl group in place of the TCS ionizable proton, affects neither degranulation nor ATP production at non-cytotoxic doses. Thus, the effects of TCS on mast cell function are due to its proton ionophore structure. In addition, 5 µm TCS inhibits thapsigargin-stimulated degranulation of RBL-2H3 cells: further evidence that TCS disrupts mast cell signaling. Our data indicate that TCS is a mitochondrial uncoupler, and TCS may affect numerous cell types and functions via this mechanism. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26204821

  5. Synthesis and antimicrobial activity of guanylhydrazones. Synthesis of 2-(2-methylthio-2-aminovinyl)-1-methylpyridinium iodides and 2-(2-methylthio-2-aminovinyl)-1-methylquinolinium iodides as potential radioprotective and anticancer agents

    SciTech Connect

    Almassian, B.

    1985-01-01

    The finding of appreciable antileukemic activity in a series of 2-(2-methylthio-2-amino)vinyl-1-methylquinolinium iodides (Foye et al., 1980, 1983) suggested that greater basicity, as compared with the corresponding dithioacetic acids, was contributing to the increase in activity. The addition of a greater degree of basicity in the design of anticancer possibilities in this series was considered worth investigation, particularly in view of the activity of a series of bis(quanylhydrazones) synthesized at Lederle Laboratories. Accordingly, a series of guanylhydrazones of 4-pyridine-,2-pyridine- and 4-quinolinecarboxyaldehydes was synthesized for anticancer as well as antibacterial screening. Also, substitution of additional basic functions in the 2-(2-methylthio-2-amino) vinyl-1-methylquinolinium and pyridinium iodide series has been made. Appreciable antimicrobial activities have been found with both 2-pyridine and 4-quinolinealdehyde guanylhydrazones, as well as with 2-(2-methylthio-2-amino)vinyl-1-methyl-pyridinium iodides. The overall approach to the synthesis of potential anticancer agents in this project is thus to observe the effect of increasing basicity of these compounds on DNA binding and anticancer activity.

  6. Association between early inhibition of DNA synthesis and the MICs and MBCs of carboxyquinolone antimicrobial agents for wild-type and mutant [gyrA nfxB(ompF) acrA] Escherichia coli K-12.

    PubMed Central

    Chow, R T; Dougherty, T J; Fraimow, H S; Bellin, E Y; Miller, M H

    1988-01-01

    Quinolone antimicrobial agents are known to interact with DNA gyrase, but the mechanism by which bacterial cell death occurs is not fully understood. In order to determine whether there is a correlation between quinolone-induced inhibition of early (i.e., 10 to 15 min) DNA synthesis and potency (MICs and MBCs), we measured the rate of DNA synthesis in log-phase Escherichia coli K-12 by using [3H]thymidine incorporation. Three quinolones (ciprofloxacin, norfloxacin, and difloxacin) were selected based on their decreasing activity against reference strain KL16. All three quinolones caused an early 50% inhibition of DNA synthesis which was proportional to MICs and MBCs (r greater than 0.99). Furthermore, 50% inhibition of DNA synthesis and MICs were nearly identical for mutant strains with an altered quinolone target (gyrA) or with decreased [nfxB(ompF)] or increased (acrA) permeability. There were significant differences (P less than 0.001) between individual quinolones in the degree of DNA synthesis inhibition in nalidixic acid-resistant gyrA and nfxB(ompF) mutant strains. The comparison of the three mutants with the wild-type strain permitted an in vivo examination of the effects of alterations of the drug target or entry on the activity determined by DNA synthesis inhibition and MICs. PMID:3056251

  7. Antimicrobial polypeptide multilayer nanocoatings.

    PubMed

    Rudra, Jai S; Dave, Komal; Haynie, Donald T

    2006-01-01

    A multilayer coating (or film) of nanometer-thick layers can be made by sequential adsorption of oppositely charged polyelectrolytes on a solid support. The method is known as layer-by-layer assembly (LBL). No special apparatus is required for LBL and nanofilms can be prepared under mild, physiological conditions. A multilayer nanofilm in which at least one of the constituent species is a polypeptide is a polypeptide multilayer nanofilm. The present work was aimed at assessing whether polypeptide multilayer nanofilms with specific antimicrobial properties could be prepared by incorporation of a known antimicrobial agent in the film structure, in this case the edible protein hen egg white lysozyme (HEWL). The chicken enzyme is widely employed as a human food preservative. An advantage of LBL in this context is that the nanofilm is fabricated directly on the surface of interest, eliminating the need to incorporate the antimicrobial in other packaging materials. Here, nanofilms were made of poly(L-glutamic acid) (PLGA), which is highly negatively charged in the mildly acidic pH range, and HEWL, which has a high net positive charge at acidic pH. We show that PLGA/HEWL nanofilms inhibit growth of the model microbe Microccocus luteus in the surrounding liquid medium. The amount of HEWL released from PLGA/HEWL films depends on the number of HEWL layers and therefore on the total quantity of HEWL in the films. This initial study provides a sketch of the scope for further development of LBL in the area of antimicrobial polypeptide multilayer films. Potential applications of such films include strategies for food preservation and coatings for implant devices. PMID:17176751

  8. Screening of antimicrobial agents for in vitro radiation protection and mitigation capacity, including those used in supportive care regimens for bone marrow transplant recipients.

    PubMed

    Epperly, Michael W; Franicola, Darcy; Shields, Donna; Rwigema, Jean-Claude; Stone, Brandon; Zhang, Xichen; McBride, William; Georges, George; Wipf, Peter; Greenberger, Joel S

    2010-01-01

    Antibiotic and antifungal agents used in supportive care regimens for bone marrow transplantation recipients contribute to a significant dose-modifying effect of otherwise lethal total body irradiation. To determine whether drugs used in supportive care and other commonly used antibiotics such as tetracycline function as radiation protectors or damage mitigators in vitro, 13 drugs were tested for radiation protection and radiation damage mitigation of 32D cl 3 hematopoietic progenitor cells in clonagenic survival curves in vitro. Antibiotic/Antifungal agents including cilastatin, amikacin, ceftazidine, vancomycin, tetracycline, doxycycline, ciprofloxacin, metronidazole, methacycline, minocycline, meclocycline, oxytetracycline and rolitetracycline were added in 1, 10, or 100 micromolar concentrations to murine interleukin-3-dependent hematopoietic progenitor cell line 32D cl 3 cells either before or after irradiation of 0 to 8 Gy. Control irradiated 32D cl 3 cells showed radiosensitivity comparable to freshly explanted mouse marrow hematopoietic progenitor cells (D(0) 1.1+/-0.1 Gy, N 1.5+/-0.4). Positive control GS-nitroxide JP4-039 (known radiation mitigator) treated 32D cl 3 cells were radioresistant (D(0) 1.2+/-0.1, N 5.8+/-2.4 (p=0.009)). Of the 13 drugs tested, tetracycline was found to be a significant radiation mitigator (D(0) 0.9+/-0.1, N 13.9+/-0.4 (p=0.0027)). Thus, the radiation dose-modifying effect of some antibiotics, but not those currently used in the supportive care (antibiotic/antifungal regimens) for marrow transplant patients, may act as radiation damage mitigators for hematopoietic cells as well as decreasing the growth and inflammatory response to microbial pathogens. PMID:20133970

  9. 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. PMID:23654251

  10. 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

  11. [Susceptibilities of clinical bacterial isolates to antimicrobial agents. A study mainly focused on imipenem. Reported by the Research Group for Testing Imipenem Susceptibility on Clinical Isolates].

    PubMed

    Igari, J

    1990-11-01

    This study was conducted to investigate susceptibilities of clinical bacterial isolates to imipenem (IPM) and other antibacterial agents at 64 hospital laboratories throughout Japan from September to December of 1988. In this study, identification and susceptibility testing were carried out at each laboratory and the tests were performed according to the disk dilution method recommended by NCCLS in which susceptibilities are classified into "S", "MS", "I" and "R". IPM showed markedly high in vitro activities against Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Enterococcus faecalis, Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae, Serratia marcescens, Salmonella spp., Citrobacter freundii, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Providencia rettgeri, Providencia stuartii, Acinetobacter calcoaceticus, Moraxella (Branhamella) catarrhalis, Alcaligenes spp., Peptococcus spp./Peptostreptococcus spp., Bacteroides fragilis and Bacteroides spp. IPM also had strong activities against Achromobacter xylosoxidans and Pseudomonas aeruginosa, but less active against Flavobacterium spp., E. faecium, coagulase-negative staphylococci (CNS), Staphylococcus aureus and Pseudomonas cepacia. In a study in which activities of IPM against bacteria isolated from different clinical sources were compared, differences in susceptibilities were observed among S. aureus, CNS, A. calcoaceticus and P. aeruginosa, but such differences were not apparent among S. pneumoniae, E. faecalis, H. influenzae, E. coli, K. pneumoniae, E. cloacae, C. freundii, S. marcescens or P. mirabilis. PMID:2287060

  12. In vitro susceptibility of community-acquired urinary tract pathogens to commonly used antimicrobial agents in Spain: a comparative multicenter study (2002-2004).

    PubMed

    Garcia Garcia, M I; Munoz Bellido, J L; Garcia Rodriguez, J A

    2007-06-01

    The susceptibility patterns of 2724 uropathogens isolated in 9 Spanish regions during 2002, and 3013 obtained in 2004 were determined. The antibiotics tested were fosfomycin trometamol, amoxicillin, co-amoxiclav, cefixime, cefuroxime-axetil, pipemidic, ceprofloxacin, trimethoprim plus sulphamethoxazole and nitrofurantoin. Escherichia coli was the main pathogen in both studies (73% vs. 68.3%) followed by Proteus mirabilis 7.2% vs. 6.4%) and Klebsiella pneumoniae (5.4% vs. 5.2%). Enteroccocus spp. (4.7% vs. 6.8%), Streptoccocus agalactiae (1.7% vs. 3.1%) and Staphyloccocus saprophyticus (0.7% vs. 1.3%)were the most frequent Gram-positive pathogens. 31.3% of E. coli in 2002 and 32% in 2004 were susceptible to all antibiotics tested. Around 40% of E. coli were resistant to a single agent. 21.6-24.1% were resistant to two antibiotics. 35.4% of first period isolates, and 37.6% of second period ones were resistant to two or more classes of antibiotics. Fosfomycin (2.1- 2.8%) and nitrofurantoin (3.5-5.7%) had the lowest resistance rates for E. coli. Amoxicillin (58.2-58.7%), co-trimoxazole (30.8-33.8%) and ciprofloxacin (22.6-22.7%) showed the highest resistance rates, and their suitability as empiric treatments for UTI should probably be re-evaluated. PMID:17594920

  13. Biopolymer-based antimicrobial packaging: a review.

    PubMed

    Cha, Dong Su; Chinnan, Manjeet S

    2004-01-01

    The term antimicrobialpackaging encompasses any packaging technique(s) used to control microbial growth in a food product. These include packaging materials and edible films and coatings that contain antimicrobial agents and also techniques that modify the atmosphere within the package. In recent years, antimicrobial packaging has attracted much attention from the food industry because of the increase in consumer demand for minimally processed, preservative-free products. Reflecting this demand, the preservative agents must be applied to packaging in such away that only low levels of preservatives come into contact with the food. The film or coating technique is considered to be more effective, although more complicated to apply. New antimicrobial packaging materials are continually being developed. Many of them exploit natural agents to control common food-borne microorganisms. Current trends suggest that, in due course, packaging will generally incorporate antimicrobial agents, and the sealing systems will continue to improve. The focus of packaging in the past has been on the appearance, size, and integrity of the package. A greater emphasis on safety features associated with the addition of antimicrobial agents is perhaps the next area for development in packaging technology. PMID:15462127

  14. New antimicrobial molecules and new antibiotic strategies.

    PubMed

    Rodríguez de Castro, Felipe; Naranjo, Olga Rajas; Marco, Javier Aspa; Violán, Jordi Solé

    2009-04-01

    Drug options for treatment of infections are increasingly limited. The pharmaceutical industry has found it difficult to discover new antimicrobial agents, and only two novel classes of antibiotics, the oxazolidinones and the cyclic lipopeptides, have entered the market since the late 1960s. Few new agents have reached the market in the last decade with potential interest for community-acquired pneumonia (CAP) treatment, including linezolid (the first oxazolidinone in clinical use), new fluoroquinolones, cefditoren, ertapenem, and telithromycin. Agents currently in clinical development include other novel quinolones and ketolides, broad-spectrum cephalosporin derivatives, faropenem, several glycopeptides, and iclaprim. Other molecules are considered to be promising candidates for the future. In addition to the foregoing agents, alternative treatment approaches have also been introduced into clinical practice, which include the administration of the appropriate antimicrobials in a timely manner and the consideration of the pharmacokinetic-pharmacodynamic properties of the agent(s). PMID:19296416

  15. Sensitization of Intracellular Salmonella enterica Serovar Typhimurium to Aminoglycosides In Vitro and In Vivo by a Host-Targeted Antimicrobial Agent

    PubMed Central

    Lo, Jung-Hsin; Kulp, Samuel K.; Chen, Ching-Shih

    2014-01-01

    Aminoglycosides exhibit relatively poor activity against intracellular Salmonella enterica serovar Typhimurium due to their low permeativity across eukaryotic cell membranes. Previously, we identified the unique ability of AR-12, a celecoxib-derived small-molecule agent, to eradicate intracellular Salmonella Typhimurium in macrophages by facilitating autophagosome formation and suppressing Akt kinase signaling. In light of this unique mode of antibacterial action, we investigated the ability of AR-12 to sensitize intracellular Salmonella to aminoglycosides in macrophages and in an animal model. The antibacterial activities of AR-12 combined with various aminoglycosides, including streptomycin, kanamycin, gentamicin, and amikacin, against intracellular S. Typhimurium in murine RAW264.7 macrophages were assessed. Cells were infected with S. Typhimurium followed by treatment with AR-12 or individual aminoglycosides or with combinations for 24 h. The in vivo efficacies of AR-12, alone or in combination with gentamicin or amikacin, were also assessed by treating S. Typhimurium-infected BALB/c mice daily for 14 consecutive days. Exposure of S. Typhimurium-infected RAW264.7 cells to a combination of AR-12 with individual aminoglycosides led to a reduction in bacterial survival (P < 0.05), both intracellular and extracellular, that was greater than that seen with the aminoglycosides alone. This sensitizing effect, however, was not associated with increased aminoglycoside penetration into bacteria or macrophages. Moreover, daily intraperitoneal injection of AR-12 at 0.1 mg/kg of body weight significantly increased the in vivo efficacy of gentamicin and amikacin in prolonging the survival of S. Typhimurium-infected mice. These findings indicate that the unique ability of AR-12 to enhance the in vivo efficacy of aminoglycosides might have translational potential for efforts to develop novel strategies for the treatment of salmonellosis. PMID:25267669

  16. Clinical outcomes of tigecycline alone or in combination with other antimicrobial agents for the treatment of patients with healthcare-associated multidrug-resistant Acinetobacter baumannii infections.

    PubMed

    Lee, Y-T; Tsao, S-M; Hsueh, P-R

    2013-09-01

    Tigecycline (TG) has been shown to be active in vitro against Acinetobacter baumannii, although data on the clinical efficacy of TG alone or in combination for the treatment of infections due to multidrug-resistant A. baumannii (MDRAB) remain limited. The purpose of this study was to investigate the clinical outcomes of patients with healthcare-associated infections (HAIs) caused by MDRAB who were treated with imipenem/cilastatin and sulbactam, and TG alone or in combination with other antibiotics. A total of 386 patients with HAIs caused by MDRAB were retrospectively analyzed and grouped into TG and non-TG groups, depending on whether they received TG treatment. Of the 266 patients in the TG group, 108 were treated with TG alone and 158 were treated with TG in combination with ceftazidime, ceftriaxone, piperacillin/tazobactam, or a carbapenem. All 120 patients in the non-TG group were treated with imipenem/cilastatin and sulbactam. The primary outcome measure was 30-day mortality after TG treatment and the secondary outcome was clinical outcome. There were no significant differences in survival rates between the two groups. However, the rate of unfavorable outcome was significantly lower (p < 0.05) among patients in the TG group than among patients in the non-TG group. The most significant predictor of unfavorable outcome was sepsis, whereas TG treatment and microbial eradication were the most significant predictors of favorable outcomes. Our study represents the largest study of patients with MDRAB infection treated with TG and expands our understanding of the role of TG therapy alone or in combination with other agents for the treatment of HAI caused by MDRAB. PMID:23553594

  17. Comparative in vitro activity of ceftaroline, ceftaroline-avibactam, and other antimicrobial agents against aerobic and anaerobic bacteria cultured from infected diabetic foot wounds.

    PubMed

    Goldstein, Ellie J C; Citron, Diane M; Merriam, C Vreni; Tyrrell, Kerin L

    2013-07-01

    Foot infections are the most common infectious complication of diabetes. Moderate to severe diabetic foot infections (DFI) are typically polymicrobial with both aerobic and anaerobic organisms. The role of MRSA in these wounds has become an increasing concern. To determine if the addition of avibactam, a novel non-beta-lactam beta-lactamase inhibitor, to ceftaroline would be more active than ceftaroline alone, we tested 316 aerobic pathogens and 154 anaerobic recovered from patients with moderate to severe DFI, and compared ceftaroline with and without avibactam to other agents. Testing on aerobes was done by broth microdilution and by agar dilution for anaerobes, according to CLSI M11-A8, and M7-A8 standards. Ceftaroline-avibactam MIC90 for all Staphylococcus spp. including MRSA was 0.5 μg/mL, and for enterococci was 1 μg/mL. The MIC90s for enteric Gram-negative rods was 0.125 μg/mL. The addition of avibactam to ceftaroline reduced the ceftaroline MICs for 2 strains of resistant Enterobacter spp. and for 1 strain of Morganella. Against anaerobic Gram-positive cocci ceftaroline-avibactam had an MIC90 0.125 μg/mL and for clostridia 1 μg/mL. Avibactam improved ceftaroline's MIC90s for Bacteroides fragilis from >32 to 2 μg/mL and for Prevotella spp. from >32 to 1 μg/mL. Ceftaroline alone demonstrates excellent in vitro activity against most of the aerobes found in moderate to severe DFI. The addition of avibactam provides an increased spectrum of activity including the beta-lactamase producing Prevotella, Bacteroides fragilis and ceftaroline resistant gram-negative enteric organisms. PMID:23623385

  18. Antimicrobial properties of analgesic kyotorphin peptides unraveled through atomic force microscopy

    SciTech Connect

    Ribeiro, Marta M.B.; Franquelim, Henri G.; Torcato, Ines M.; Ramu, Vasanthakumar G.; Heras, Montserrat; Bardaji, Eduard R.; Castanho, Miguel A.R.B.

    2012-04-13

    Highlights: Black-Right-Pointing-Pointer New kyotorphin derivatives have antimicrobial properties against S. aureus. Black-Right-Pointing-Pointer Atomic force microscopy show membrane disturbing effects of KTP-NH{sub 2} and IbKTP-NH{sub 2}. Black-Right-Pointing-Pointer None of the KTP derivatives are hemolytic. Black-Right-Pointing-Pointer The minimal peptidic sequence with antimicrobial activity is Tyr-Arg, if amidated. -- Abstract: Antimicrobial peptides (AMPs) are promising candidates as alternatives to conventional antibiotics for the treatment of resistant pathogens. In the last decades, new AMPs have been found from the cleavage of intact proteins with no antibacterial activity themselves. Bovine hemoglobin hydrolysis, for instance, results in AMPs and the minimal antimicrobial peptide sequence was defined as Tyr-Arg plus a positively charged amino acid residue. The Tyr-Arg dipeptide alone, known as kyotorphin (KTP), is an endogenous analgesic neuropeptide but has no antimicrobial activity itself. In previous studies new KTP derivatives combining C-terminal amidation and Ibuprofen (Ib) - KTP-NH{sub 2}, IbKTP, IbKTP-NH{sub 2} - were designed in order to improve KTP brain targeting. Those modifications succeeded in enhancing peptide-cell membrane affinity towards fluid anionic lipids and higher analgesic activity after systemic injection resulted therefrom. Here, we investigated if this affinity for anionic lipid membranes also translates into antimicrobial activity because bacteria have anionic membranes. Atomic force microscopy revealed that KTP derivatives perturbed Staphylococcus aureus membrane structure by inducing membrane blebbing, disruption and lysis. In addition, these peptides bind to red blood cells but are non-hemolytic. From the KTP derivatives tested, amidated KTP proves to be the most active antibacterial agent. The combination of analgesia and antibacterial activities with absence of toxicity is highly appealing from the clinical point of view

  19. Helical Antimicrobial Sulfono- {gamma} -AApeptides

    SciTech Connect

    Li, Yaqiong; Wu, Haifan; Teng, Peng; Bai, Ge; Lin, Xiaoyang; Zuo, Xiaobing; Cao, Chuanhai; Cai, Jianfeng

    2015-06-11

    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, are 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.

  20. Antimicrobial Polymers with Metal Nanoparticles

    PubMed Central

    Palza, Humberto

    2015-01-01

    Metals, such as copper and si