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Sample records for gram-positive bacteria induced

  1. Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria

    DEFF Research Database (Denmark)

    Johansen, Charlotte; Verheul, A.; Gram, Lone

    1997-01-01

    carboxyfluorescein and ATP after 2 to 5 min. Maximum antibacterial activity was reached at alkaline pH and in the absence of divalent cations. The efficient permeabilization of cell envelopes of both gram-positive and gram-negative bacteria suggests that protamine causes a general disruption of the cell envelope...

  2. Transformation of gram positive bacteria by sonoporation

    Science.gov (United States)

    Yang, Yunfeng; Li, Yongchao

    2014-03-11

    The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

  3. Gram-positive and gram-negative bacteria induce different patterns of cytokine production in human mononuclear cells irrespective of taxonomic relatedness.

    Science.gov (United States)

    Skovbjerg, Susann; Martner, Anna; Hynsjö, Lars; Hessle, Christina; Olsen, Ingar; Dewhirst, Floyd E; Tham, Wilhelm; Wold, Agnes E

    2010-01-01

    Upon bacterial stimulation, tissue macrophages produce a variety of cytokines that orchestrate the immune response that clears the infection. We have shown that Gram-positives induce higher levels of interleukin-12 (IL-12), interferon-gamma (IFN-gamma), and tumor necrosis factor (TNF) from human peripheral blood mononuclear cells (PBMCs) than do Gram-negatives, which instead induce more of IL-6, IL-8, and IL-10. Here, we study whether these patterns follows or crosses taxonomic borders. PBMCs from blood donors were incubated with UV-inactivated bacteria representing 37 species from five phyla. IL-12, TNF, IL-1beta, IL-6, IL-8, and IL-10 were measured in the supernatants after 24 h and IFN-gamma after 5 days. Irrespective of phylogenetic position, Gram-positive bacteria induced much more IL-12 (nine times more on average) and IFN-gamma (seven times), more TNF (three times), and slightly more IL-1beta (1.5 times) than did Gram-negatives, which instead induced more IL-6 (1.5 times), IL-8 (1.9 times), and IL-10 (3.3 times) than did Gram-positives. A notable exception was the Gram-positive Listeria monocytogenes, which induced very little IL-12, IFN-gamma, and TNF. The results confirm the fundamental difference in innate immune responses to Gram-positive and Gram-negative bacteria, which crosses taxonomic borders and probably reflects differences in cell wall structure.

  4. Glass bead transformation method for gram-positive bacteria

    OpenAIRE

    Rattanachaikunsopon, Pongsak; Phumkhachorn, Parichat

    2009-01-01

    A simple, inexpensive and reproducible transformation method was developed for Gram-positive bacteria. It was based on agitation of bacterial protoplasts with glass beads in the presence of DNA and polyethylene glycol. By using this method, introduction of pGK12 into protoplasts of several strains of Gram-positive bacteria was achieved.

  5. Gram-positive bacteria persisting in the food production environment

    DEFF Research Database (Denmark)

    Knøchel, Susanne; Harmsen, Morten; Knudsen, Bettina

    2008-01-01

    Many gram-positive bacteria are able to form aggregates or biofilms and resist external stress factors and some gram-positive pathogenic bacteria such as Listeria monocytogenes and Bacillus cereus may persist in the food production environment for extended periods. Most research has focussed...

  6. A Synthetic Dual Drug Sideromycin Induces Gram-Negative Bacteria To Commit Suicide with a Gram-Positive Antibiotic.

    Science.gov (United States)

    Liu, Rui; Miller, Patricia A; Vakulenko, Sergei B; Stewart, Nichole K; Boggess, William C; Miller, Marvin J

    2018-05-10

    Many antibiotics lack activity against Gram-negative bacteria because they cannot permeate the outer membrane or suffer from efflux and, in the case of β-lactams, are degraded by β-lactamases. Herein, we describe the synthesis and studies of a dual drug conjugate (1) of a siderophore linked to a cephalosporin with an attached oxazolidinone. The cephalosporin component of 1 is rapidly hydrolyzed by purified ADC-1 β-lactamase to release the oxazolidinone. Conjugate 1 is active against clinical isolates of Acinetobacter baumannii as well as strains producing large amounts of ADC-1 β-lactamase. Overall, the results are consistent with siderophore-mediated active uptake, inherent activity of the delivered dual drug, and in the presence of β-lactamases, intracellular release of the oxazolidinone upon cleavage of the cephalosporin to allow the freed oxazolidinone to inactivate its target. The ultimate result demonstrates that Gram-positive oxazolidinone antibiotics can be made to be effective against Gram-negative bacteria by β-lactamase triggered release.

  7. Methods for targetted mutagenesis in gram-positive bacteria

    Science.gov (United States)

    Yang, Yunfeng

    2014-05-27

    The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

  8. Defining a role for Hfq in Gram-positive bacteria

    DEFF Research Database (Denmark)

    Nielsen, Jesper Sejrup; Lei, Lisbeth Kristensen; Ebersbach, Tine

    2010-01-01

    Small trans-encoded RNAs (sRNAs) modulate the translation and decay of mRNAs in bacteria. In Gram-negative species, antisense regulation by trans-encoded sRNAs relies on the Sm-like protein Hfq. In contrast to this, Hfq is dispensable for sRNA-mediated riboregulation in the Gram-positive species......-dependent and -independent mechanisms, thus adding another layer of complexity to sRNA-mediated riboregulation in Gram-positive species....

  9. Nicotinoprotein methanol dehydrogenase enzymes in Gram-positive methylotrophic bacteria

    NARCIS (Netherlands)

    Hektor, Harm J.; Kloosterman, Harm; Dijkhuizen, Lubbert

    2000-01-01

    A novel type of alcohol dehydrogenase enzyme has been characterized from Gram-positive methylotrophic (Bacillus methanolicus, the actinomycetes Amycolatopsis methanolica and Mycobacterium gastri) and non-methylotrophic bacteria (Rhodococcus strains). Its in vivo role is in oxidation of methanol and

  10. Gram-negative, but not Gram-positive, bacteria elicit strong PGE2 production in human monocytes.

    Science.gov (United States)

    Hessle, Christina C; Andersson, Bengt; Wold, Agnes E

    2003-12-01

    Gram-positive and Gram-negative bacteria induce different cytokine patterns in human mononuclear cells. We have seen that Gram-positives preferentially induce IL-12 and TNF-alpha, whereas Gram-negatives induce more IL-10, IL-6, and IL-8. In this study, we compared the capacity of these two groups of bacteria to induce PGE2. Monocytes stimulated with Gram-negative bacterial species induced much more PGE2 than did Gram-positive bacteria (5600 +/- 330 vs. 1700 +/- 670 pg/mL, p Gram-positive and Gram-negative bacteria. We suggest that Gram-positive and Gram-negative bacteria may stimulate different innate effector functions; Gram-positive bacteria promoting cell-mediated effector functions whereas Gram-negative bacteria inducing mediators inhibiting the same.

  11. Transcriptional attenuation controls macrolide inducible efflux and resistance in Streptococcus pneumoniae and in other Gram-positive bacteria containing mef/mel(msr(D)) elements.

    Science.gov (United States)

    Chancey, Scott T; Bai, Xianhe; Kumar, Nikhil; Drabek, Elliott F; Daugherty, Sean C; Colon, Thomas; Ott, Sandra; Sengamalay, Naomi; Sadzewicz, Lisa; Tallon, Luke J; Fraser, Claire M; Tettelin, Hervé; Stephens, David S

    2015-01-01

    Macrolide resistance, emerging in Streptococcus pneumoniae and other Gram-positive bacteria, is increasingly due to efflux pumps encoded by mef/mel(msr) operons found on discrete mobile genetic elements. The regulation of mef/mel(msr) in these elements is not well understood. We identified the mef(E)/mel transcriptional start, localized the mef(E)/mel promoter, and demonstrated attenuation of transcription as a mechanism of regulation of macrolide-inducible mef-mediated macrolide resistance in S. pneumoniae. The mef(E)/mel transcriptional start site was a guanine 327 bp upstream of mef(E). Consensus pneumococcal promoter -10 (5'-TATACT-3') and -35 (5'-TTGAAC-3') boxes separated by 17 bp were identified 7 bp upstream of the start site. Analysis of the predicted secondary structure of the 327 5' region identified four pairs of inverted repeats R1-R8 predicted to fold into stem-loops, a small leader peptide [MTASMRLR, (Mef(E)L)] required for macrolide induction and a Rho-independent transcription terminator. RNA-seq analyses provided confirmation of transcriptional attenuation. In addition, expression of mef(E)L was also influenced by mef(E)L-dependent mRNA stability. The regulatory region 5' of mef(E) was highly conserved in other mef/mel(msr)-containing elements including Tn1207.1 and the 5612IQ complex in pneumococci and Tn1207.3 in Group A streptococci, indicating a regulatory mechanism common to a wide variety of Gram-positive bacteria containing mef/mel(msr) elements.

  12. Selenoproteins in Archaea and Gram-positive bacteria.

    Science.gov (United States)

    Stock, Tilmann; Rother, Michael

    2009-11-01

    Selenium is an essential trace element for many organisms by serving important catalytic roles in the form of the 21st co-translationally inserted amino acid selenocysteine. It is mostly found in redox-active proteins in members of all three domains of life and analysis of the ever-increasing number of genome sequences has facilitated identification of the encoded selenoproteins. Available data from biochemical, sequence, and structure analyses indicate that Gram-positive bacteria synthesize and incorporate selenocysteine via the same pathway as enterobacteria. However, recent in vivo studies indicate that selenocysteine-decoding is much less stringent in Gram-positive bacteria than in Escherichia coli. For years, knowledge about the pathway of selenocysteine synthesis in Archaea and Eukarya was only fragmentary, but genetic and biochemical studies guided by analysis of genome sequences of Sec-encoding archaea has not only led to the characterization of the pathways but has also shown that they are principally identical. This review summarizes current knowledge about the metabolic pathways of Archaea and Gram-positive bacteria where selenium is involved, about the known selenoproteins, and about the respective pathways employed in selenoprotein synthesis.

  13. RNases and Helicases in Gram-Positive Bacteria.

    Science.gov (United States)

    Durand, Sylvain; Condon, Ciaran

    2018-04-01

    RNases are key enzymes involved in RNA maturation and degradation. Although they play a crucial role in all domains of life, bacteria, archaea, and eukaryotes have evolved with their own sets of RNases and proteins modulating their activities. In bacteria, these enzymes allow modulation of gene expression to adapt to rapidly changing environments. Today, >20 RNases have been identified in both Escherichia coli and Bacillus subtilis , the paradigms of the Gram-negative and Gram-positive bacteria, respectively. However, only a handful of these enzymes are common to these two organisms and some of them are essential to only one. Moreover, although sets of RNases can be very similar in closely related bacteria such as the Firmicutes Staphylococcus aureus and B. subtilis , the relative importance of individual enzymes in posttranscriptional regulation in these organisms varies. In this review, we detail the role of the main RNases involved in RNA maturation and degradation in Gram-positive bacteria, with an emphasis on the roles of RNase J1, RNase III, and RNase Y. We also discuss how other proteins such as helicases can modulate the RNA-degradation activities of these enzymes.

  14. Mid-infrared spectroscopic assessment of nanotoxicity in gram-negative vs. gram-positive bacteria.

    Science.gov (United States)

    Heys, Kelly A; Riding, Matthew J; Strong, Rebecca J; Shore, Richard F; Pereira, M Glória; Jones, Kevin C; Semple, Kirk T; Martin, Francis L

    2014-03-07

    Nanoparticles appear to induce toxic effects through a variety of mechanisms including generation of reactive oxygen species (ROS), physical contact with the cell membrane and indirect catalysis due to remnants from manufacture. The development and subsequent increasing usage of nanomaterials has highlighted a growing need to characterize and assess the toxicity of nanoparticles, particularly those that may have detrimental health effects such as carbon-based nanomaterials (CBNs). Due to interactions of nanoparticles with some reagents, many traditional toxicity tests are unsuitable for use with CBNs. Infrared (IR) spectroscopy is a non-destructive, high throughput technique, which is unhindered by such problems. We explored the application of IR spectroscopy to investigate the effects of CBNs on Gram-negative (Pseudomonas fluorescens) and Gram-positive (Mycobacterium vanbaalenii PYR-1) bacteria. Two types of IR spectroscopy were compared: attenuated total reflection Fourier-transform infrared (ATR-FTIR) and synchrotron radiation-based FTIR (SR-FTIR) spectroscopy. This showed that Gram-positive and Gram-negative bacteria exhibit differing alterations when exposed to CBNs. Gram-positive bacteria appear more resistant to these agents and this may be due to the protection afforded by their more sturdy cell wall. Markers of exposure also vary according to Gram status; Amide II was consistently altered in Gram-negative bacteria and carbohydrate altered in Gram-positive bacteria. ATR-FTIR and SR-FTIR spectroscopy could both be applied to extract biochemical alterations induced by each CBN that were consistent across the two bacterial species; these may represent potential biomarkers of nanoparticle-induced alterations. Vibrational spectroscopy approaches may provide a novel means of fingerprinting the effects of CBNs in target cells.

  15. A classification system for plasmids from Enterococci and other Gram-positive bacteria

    DEFF Research Database (Denmark)

    Jensen, Lars Bogø; Garcia-Migura, Lourdes; Valenzuela, Antonio Jesus Sanchez

    2010-01-01

    A classification system for plasmids isolated from enterococci and other Gram-positive bacteria was developed based on 111 published plasmid sequences from enterococci and other Gram-positive bacteria; mostly staphylococci. Based on PCR amplification of conserved areas of the replication initiating....... Furthermore, conjugation experiments were performed obtaining 30 transconjugants when selecting for antimicrobial resistance. Among them 19 gave no positive amplicons indicating presence of rep-families not tested for in this experimental setup....

  16. Nucleotide sequence alignment of hdcA from Gram-positive bacteria.

    Science.gov (United States)

    Diaz, Maria; Ladero, Victor; Redruello, Begoña; Sanchez-Llana, Esther; Del Rio, Beatriz; Fernandez, Maria; Martin, Maria Cruz; Alvarez, Miguel A

    2016-03-01

    The decarboxylation of histidine -carried out mainly by some gram-positive bacteria- yields the toxic dietary biogenic amine histamine (Ladero et al. 2010 〈10.2174/157340110791233256〉 [1], Linares et al. 2016 〈http://dx.doi.org/10.1016/j.foodchem.2015.11.013〉〉 [2]). The reaction is catalyzed by a pyruvoyl-dependent histidine decarboxylase (Linares et al. 2011 〈10.1080/10408398.2011.582813〉 [3]), which is encoded by the gene hdcA. In order to locate conserved regions in the hdcA gene of Gram-positive bacteria, this article provides a nucleotide sequence alignment of all the hdcA sequences from Gram-positive bacteria present in databases. For further utility and discussion, see 〈http://dx.doi.org/ 10.1016/j.foodcont.2015.11.035〉〉 [4].

  17. In vitro activity of daptomycin against clinical isolates of Gram-positive bacteria.

    Science.gov (United States)

    Piper, Kerryl E; Steckelberg, James M; Patel, Robin

    2005-08-01

    We determined the activity of daptomycin, a recently FDA-approved antimicrobial agent, against clinical isolates of Gram-positive bacteria, including viridans group streptococci (16 Streptococcus mitis species group, 12 S. mutans species group, 9 S. anginosus species group, 8 S. sanguinis species group, 5 S. salivarius species group) from patients with infective endocarditis, 32 methicillin-resistant Staphylococcus aureus, 32 high-level penicillin-resistant Streptococcus pneumoniae, 38 vancomycin-resistant enterococci (including 1 linezolid-resistant isolate), and the following unusual Gram-positive bacteria: 3 Listeria monocytogenes, 4 Erysipelothrix rhusiopathiae, 9 Corynebacterium species, 10 Abiotrophia/Granulicatella species, 2 Rothia (Stomatococcus) mucilaginosus, and 4 Gemella morbillorum. Daptomycin minimum inhibitory concentration (MIC)(90) values for the viridans group streptococci, methicillin-resistant S. aureus, penicillin-resistant S. pneumoniae, and Enterococcus species were 0.5, 0.5, endocarditis as well as against several types of unusual Gram-positive bacteria that can cause endocarditis.

  18. Trans-generational Immune Priming Protects the Eggs Only against Gram-Positive Bacteria in the Mealworm Beetle

    Science.gov (United States)

    Dubuffet, Aurore; Zanchi, Caroline; Boutet, Gwendoline; Moreau, Jérôme; Teixeira, Maria; Moret, Yannick

    2015-01-01

    In many vertebrates and invertebrates, offspring whose mothers have been exposed to pathogens can exhibit increased levels of immune activity and/or increased survival to infection. Such phenomena, called “Trans-generational immune priming” (TGIP) are expected to provide immune protection to the offspring. As the offspring and their mother may share the same environment, and consequently similar microbial threats, we expect the immune molecules present in the progeny to be specific to the microbes that immune challenged the mother. We provide evidence in the mealworm beetle Tenebrio molitor that the antimicrobial activity found in the eggs is only active against Gram-positive bacteria, even when females were exposed to Gram-negative bacteria or fungi. Fungi were weak inducers of TGIP while we obtained similar levels of anti-Gram-positive activity using different bacteria for the maternal challenge. Furthermore, we have identified an antibacterial peptide from the defensin family, the tenecin 1, which spectrum of activity is exclusively directed toward Gram-positive bacteria as potential contributor to this antimicrobial activity. We conclude that maternal transfer of antimicrobial activity in the eggs of T. molitor might have evolved from persistent Gram-positive bacterial pathogens between insect generations. PMID:26430786

  19. Trans-generational Immune Priming Protects the Eggs Only against Gram-Positive Bacteria in the Mealworm Beetle.

    Directory of Open Access Journals (Sweden)

    Aurore Dubuffet

    2015-10-01

    Full Text Available In many vertebrates and invertebrates, offspring whose mothers have been exposed to pathogens can exhibit increased levels of immune activity and/or increased survival to infection. Such phenomena, called "Trans-generational immune priming" (TGIP are expected to provide immune protection to the offspring. As the offspring and their mother may share the same environment, and consequently similar microbial threats, we expect the immune molecules present in the progeny to be specific to the microbes that immune challenged the mother. We provide evidence in the mealworm beetle Tenebrio molitor that the antimicrobial activity found in the eggs is only active against Gram-positive bacteria, even when females were exposed to Gram-negative bacteria or fungi. Fungi were weak inducers of TGIP while we obtained similar levels of anti-Gram-positive activity using different bacteria for the maternal challenge. Furthermore, we have identified an antibacterial peptide from the defensin family, the tenecin 1, which spectrum of activity is exclusively directed toward Gram-positive bacteria as potential contributor to this antimicrobial activity. We conclude that maternal transfer of antimicrobial activity in the eggs of T. molitor might have evolved from persistent Gram-positive bacterial pathogens between insect generations.

  20. Electrochemical reduction of oxygen catalyzed by a wide range of bacteria including Gram-positive

    Energy Technology Data Exchange (ETDEWEB)

    Cournet, Amandine [Universite de Toulouse, UPS, LU49, Adhesion Bacterienne et Formation de Biofilms, 35 chemin des Maraichers, 31 062 Toulouse cedex 09 (France); Laboratoire de Genie Chimique CNRS, Universite de Toulouse, 4 allee Emile Monso, BP 84234, 31432 Toulouse cedex 04 (France); Delia, Marie-Line; Bergel, Alain [Laboratoire de Genie Chimique CNRS, Universite de Toulouse, 4 allee Emile Monso, BP 84234, 31432 Toulouse cedex 04 (France); Roques, Christine; Berge, Mathieu [Universite de Toulouse, UPS, LU49, Adhesion Bacterienne et Formation de Biofilms, 35 chemin des Maraichers, 31 062 Toulouse cedex 09 (France)

    2010-04-15

    Most bacteria known to be electrochemically active have been harvested in the anodic compartments of microbial fuel cells (MFCs) and are able to use electrodes as electron acceptors. The reverse phenomenon, i.e. using solid electrodes as electron donors, is not so widely studied. To our knowledge, most of the electrochemically active bacteria are Gram-negative. The present study implements a transitory electrochemical technique (cyclic voltammetry) to study the microbial catalysis of the electrochemical reduction of oxygen. It is demonstrated that a wide range of aerobic and facultative anaerobic bacteria are able to catalyze oxygen reduction. Among these electroactive bacteria, several were Gram-positive. The transfer of electrons was direct since no activity was obtained with the filtrate. These findings, showing a widespread property among bacteria including Gram-positive ones, open new and interesting routes in the field of electroactive bacteria research. (author)

  1. Transformation and Stability of Cloned Polysaccharidase Genes in Gram-Positive Bacteria

    OpenAIRE

    EKİNCİ, Mehmet Sait

    2014-01-01

    Polysaccharidase genes from rumen bacteria were transferred to and expressed in ruminal and non-ruminal Gram-positive bacteria. The transformation efficiency and genetic stability of polysaccharidase genes in bacteria from different habitats were investigated. PCR amplification of cloned polysaccharidase genes from Escherichia coli, Lactococcus lactis, Enterococcus faecalis, Streptococcus sanguis and S. bovis strain 26 showed that rearrangement of plasmid and the gene fragment did not occur. ...

  2. Tribolium castaneum defensins are primarily active against Gram-positive bacteria

    Czech Academy of Sciences Publication Activity Database

    Tonk, M.; Knorr, E.; Cabezas-Cruz, A.; Valdés, James J.; Kollewe, C.; Vilcinskas, A.

    2015-01-01

    Roč. 132, NOV 2015 (2015), s. 208-215 ISSN 0022-2011 R&D Projects: GA MŠk(CZ) EE2.3.30.0032 Institutional support: RVO:60077344 Keywords : Antimicrobial peptides * Defensin * Innate immunity * Insects * Tribolium castaneum * Gram-positive bacteria Subject RIV: EI - Biotechnology ; Bionics Impact factor: 2.198, year: 2015

  3. Diversity of pigmented Gram-positive bacteria associated with marine macroalgae from Antarctica.

    Science.gov (United States)

    Leiva, Sergio; Alvarado, Pamela; Huang, Ying; Wang, Jian; Garrido, Ignacio

    2015-12-01

    Little is known about the diversity and roles of Gram-positive and pigmented bacteria in Antarctic environments, especially those associated with marine macroorganisms. This work is the first study about the diversity and antimicrobial activity of culturable pigmented Gram-positive bacteria associated with marine Antarctic macroalgae. A total of 31 pigmented Gram-positive strains were isolated from the surface of six species of macroalgae collected in the King George Island, South Shetland Islands. On the basis of 16S rRNA gene sequence similarities ≥99%, 18 phylotypes were defined, which were clustered into 11 genera of Actinobacteria (Agrococcus, Arthrobacter, Brachybacterium, Citricoccus, Kocuria, Labedella, Microbacterium, Micrococcus, Rhodococcus, Salinibacterium and Sanguibacter) and one genus of the Firmicutes (Staphylococcus). It was found that five isolates displayed antimicrobial activity against a set of macroalgae-associated bacteria. The active isolates were phylogenetically related to Agrococcus baldri, Brachybacterium rhamnosum, Citricoccus zhacaiensis and Kocuria palustris. The results indicate that a diverse community of pigmented Gram-positive bacteria is associated with Antartic macroalgae and suggest its potential as a promising source of antimicrobial and pigmented natural compounds. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Purification Techniques of Bacteriocins from Lactic Acid Bacteria and Other Gram-Positive Bacteria

    Science.gov (United States)

    Saavedra, Lucila; Sesma, Fernando

    The search for new antimicrobial peptides produced by lactic acid ­bacteria and other Gram-positive microorganisms has become an interesting field of research in the past decades. The fact that bacteriocins are active against numerous foodborne and human pathogens, are produced by generally regarded as safe (GRAS) microorganisms, and are readily degraded by proteolytic host systems makes them attractive candidates for biotechnological applications. However, before suggesting or choosing a new bacteriocin for future technology developments, it is necessary to elucidate its biochemical structure and its mode of action, which may be carried out once the bacteriocin is purified to homogeneity. This chapter focuses on describing the main strategies used for the purification of numerous bacteriocins.

  5. A synbio approach for selection of highly expressed gene variants in Gram-positive bacteria

    DEFF Research Database (Denmark)

    Ferro, Roberto; Rennig, Maja; Hernández Rollán, Cristina

    2018-01-01

    with a long history in food fermentation. We have developed a synbio approach for increasing gene expression in two Gram-positive bacteria. First of all, the gene of interest was coupled to an antibiotic resistance gene to create a growth-based selection system. We then randomised the translation initiation...... region (TIR) preceding the gene of interest and selected clones that produced high protein titres, as judged by their ability to survive on high concentrations of antibiotic. Using this approach, we were able to significantly increase production of two industrially relevant proteins; sialidase in B....... subtilis and tyrosine ammonia lyase in L. lactis. Gram-positive bacteria are widely used to produce industrial enzymes. High titres are necessary to make the production economically feasible. The synbio approach presented here is a simple and inexpensive way to increase protein titres, which can be carried...

  6. Widespread abundance of functional bacterial amyloid in Mycolata and other Gram-positive bacteria

    DEFF Research Database (Denmark)

    Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul

    2009-01-01

    extracellular fibrils were also produced. In three cases, FuBA was only revealed after extensive removal of extracellular material by saponification, indicating an integrated attachment within the cellular envelope. Spores from species within the genera Streptomyces, Bacillus and Nocardia were all coated...... analysis. We conclude that amyloid is widespread among Gram-positive bacteria and may in many species constitute a hitherto overlooked integral part of the spores and the cellular envelope....

  7. The rapid isolation of mutants of some Gram-positive bacteria

    International Nuclear Information System (INIS)

    Dijkhuizen, L.; Keijer, L.

    1981-01-01

    In this communication the authors describe a method for isolating at high frequency independent mutants of a number of Gram-positive bacteria. The method was originally developed for use with an Arthrobacter sp. and appears to work best with this and other coryneform bacteria. All the bacteria used were from the culture collections maintained at the University of Warwick or the Centre for Applied Microbiological Research. For mutagenesis using UV light, cells were grown in complex media and used while still in the logarithmic phase of growth. Details of the irradiation procedure are given in the text. (Auth.)

  8. A synbio approach for selection of highly expressed gene variants in Gram-positive bacteria.

    Science.gov (United States)

    Ferro, Roberto; Rennig, Maja; Hernández-Rollán, Cristina; Daley, Daniel O; Nørholm, Morten H H

    2018-03-08

    The market for recombinant proteins is on the rise, and Gram-positive strains are widely exploited for this purpose. Bacillus subtilis is a profitable host for protein production thanks to its ability to secrete large amounts of proteins, and Lactococcus lactis is an attractive production organism with a long history in food fermentation. We have developed a synbio approach for increasing gene expression in two Gram-positive bacteria. First of all, the gene of interest was coupled to an antibiotic resistance gene to create a growth-based selection system. We then randomised the translation initiation region (TIR) preceding the gene of interest and selected clones that produced high protein titres, as judged by their ability to survive on high concentrations of antibiotic. Using this approach, we were able to significantly increase production of two industrially relevant proteins; sialidase in B. subtilis and tyrosine ammonia lyase in L. lactis. Gram-positive bacteria are widely used to produce industrial enzymes. High titres are necessary to make the production economically feasible. The synbio approach presented here is a simple and inexpensive way to increase protein titres, which can be carried out in any laboratory within a few days. It could also be implemented as a tool for applications beyond TIR libraries, such as screening of synthetic, homologous or domain-shuffled genes.

  9. Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

    Science.gov (United States)

    Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

    2016-12-01

    Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

  10. The Role of Functional Amyloids in Multicellular Growth and Development of Gram-Positive Bacteria

    DEFF Research Database (Denmark)

    Dragoš, Anna; Kovács, Ákos T.; Claessen, Dennis

    2017-01-01

    Amyloid fibrils play pivotal roles in all domains of life. In bacteria, these fibrillar structures are often part of an extracellular matrix that surrounds the producing organism and thereby provides protection to harsh environmental conditions. Here, we discuss the role of amyloid fibrils...... in the two distant Gram-positive bacteria, Streptomyces coelicolor and Bacillus subtilis. We describe how amyloid fibrils contribute to a multitude of developmental processes in each of these systems, including multicellular growth and community development. Despite this variety of tasks, we know...... surprisingly little about how their assembly is organized to fulfill all these roles....

  11. Gram-positive bacteria of marine origin: a numerical taxonomic study on Mediterranean isolates.

    Science.gov (United States)

    Ortigosa, M; Garay, E; Pujalte, M J

    1997-12-01

    A numerical taxonomic study was performed on 65 Gram-positive wild strains of heterotrophic, aerobic, marine bacteria, and 9 reference strains. The isolates were obtained from oysters and seawater sampled monthly over one year, by direct plating on Marine Agar. The strains were characterized by 96 morphological, biochemical, physiological and nutritional tests. Clustering yielded 13 phena at 0.62 similarity level (Sl coefficient). Only one of the seven phena containing wild isolates could be identified (Bacillus marinus). A pronounced salt requirement was found in most isolates.

  12. Antimicrobial resistance in Gram-positive bacteria from Timorese River Buffalo (Bubalus bubalis) skin microbiota.

    Science.gov (United States)

    Oliveira, Manuela; Monteiro, José L; Rana, Sílvia; Vilela, Cristina L

    2010-06-01

    The Timorese River Buffalo (Bubalus bubalis) plays a major role in the East Timor economy, as it is an important source of animal protein in human nutrition. They are widely spread throughout the country and are in direct contact with the populations. In spite of this proximity, information on their microbiota is scarce. This work aimed at characterizing the skin microbiota of the East Timorese River Buffalo and its antimicrobial resistance profile. Skin swab samples were taken from 46 animals in surveys conducted in three farms located in "Suco de Nairete", Lospalos district, during July and August 2006. Bacteria were isolated and identified according to conventional microbiological procedures. A total of 456 isolates were obtained, including Gram-positive (n = 243) and Gram-negative (n = 213) bacteria. Due to their importance as potential pathogens and as vehicles for antimicrobial resistance transmission, Gram-positive cocci (n = 27) and bacilli (n = 77) isolates were further characterized, and their antimicrobial resistance profile determined by the disk diffusion method according to the Clinical and Laboratory Standards Institute guidelines. This study shows the high bacterial diversity of B. bubalis skin microbiota, representing an important first step towards understanding its importance and epidemiologic role in animal health. It also points out the potential role of these animals as vectors of antimicrobial resistant bacteria dissemination and the importance of antimicrobial resistance monitoring in developing countries.

  13. An optimized staining technique for the detection of Gram positive and Gram negative bacteria within tissue.

    Science.gov (United States)

    Becerra, Sandra C; Roy, Daniel C; Sanchez, Carlos J; Christy, Robert J; Burmeister, David M

    2016-04-12

    Bacterial infections are a common clinical problem in both acute and chronic wounds. With growing concerns over antibiotic resistance, treatment of bacterial infections should only occur after positive diagnosis. Currently, diagnosis is delayed due to lengthy culturing methods which may also fail to identify the presence of bacteria. While newer costly bacterial identification methods are being explored, a simple and inexpensive diagnostic tool would aid in immediate and accurate treatments for bacterial infections. Histologically, hematoxylin and eosin (H&E) and Gram stains have been employed, but are far from optimal when analyzing tissue samples due to non-specific staining. The goal of the current study was to develop a modification of the Gram stain that enhances the contrast between bacteria and host tissue. A modified Gram stain was developed and tested as an alternative to Gram stain that improves the contrast between Gram positive bacteria, Gram negative bacteria and host tissue. Initially, clinically relevant strains of Pseudomonas aeruginosa and Staphylococcus aureus were visualized in vitro and in biopsies of infected, porcine burns using routine Gram stain, and immunohistochemistry techniques involving bacterial strain-specific fluorescent antibodies as validation tools. H&E and Gram stain of serial biopsy sections were then compared to a modification of the Gram stain incorporating a counterstain that highlights collagen found in tissue. The modified Gram stain clearly identified both Gram positive and Gram negative bacteria, and when compared to H&E or Gram stain alone provided excellent contrast between bacteria and non-viable burn eschar. Moreover, when applied to surgical biopsies from patients that underwent burn debridement this technique was able to clearly detect bacterial morphology within host tissue. We describe a modification of the Gram stain that provides improved contrast of Gram positive and Gram negative microorganisms within host

  14. Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR.

    Science.gov (United States)

    Kim, Sung Joon; Chang, James; Singh, Manmilan

    2015-01-01

    Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Peptidoglycan Recycling in Gram-Positive Bacteria Is Crucial for Survival in Stationary Phase

    Science.gov (United States)

    Borisova, Marina; Gaupp, Rosmarie; Duckworth, Amanda; Schneider, Alexander; Dalügge, Désirée; Mühleck, Maraike; Deubel, Denise; Unsleber, Sandra; Yu, Wenqi; Muth, Günther; Bischoff, Markus; Götz, Friedrich

    2016-01-01

    ABSTRACT Peptidoglycan recycling is a metabolic process by which Gram-negative bacteria reutilize up to half of their cell wall within one generation during vegetative growth. Whether peptidoglycan recycling also occurs in Gram-positive bacteria has so far remained unclear. We show here that three Gram-positive model organisms, Staphylococcus aureus, Bacillus subtilis, and Streptomyces coelicolor, all recycle the sugar N-acetylmuramic acid (MurNAc) of their peptidoglycan during growth in rich medium. They possess MurNAc-6-phosphate (MurNAc-6P) etherase (MurQ in E. coli) enzymes, which are responsible for the intracellular conversion of MurNAc-6P to N-acetylglucosamine-6-phosphate and d-lactate. By applying mass spectrometry, we observed accumulation of MurNAc-6P in MurNAc-6P etherase deletion mutants but not in either the isogenic parental strains or complemented strains, suggesting that MurQ orthologs are required for the recycling of cell wall-derived MurNAc in these bacteria. Quantification of MurNAc-6P in ΔmurQ cells of S. aureus and B. subtilis revealed small amounts during exponential growth phase (0.19 nmol and 0.03 nmol, respectively, per ml of cells at an optical density at 600 nm [OD600] of 1) but large amounts during transition (0.56 nmol and 0.52 nmol) and stationary (0.53 nmol and 1.36 nmol) phases. The addition of MurNAc to ΔmurQ cultures greatly increased the levels of intracellular MurNAc-6P in all growth phases. The ΔmurQ mutants of S. aureus and B. subtilis showed no growth deficiency in rich medium compared to the growth of the respective parental strains, but intriguingly, they had a severe survival disadvantage in late stationary phase. Thus, although peptidoglycan recycling is apparently not essential for the growth of Gram-positive bacteria, it provides a benefit for long-term survival. PMID:27729505

  16. Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tamboli, Dhawal P.; Lee, Dae Sung, E-mail: daesung@knu.ac.kr

    2013-09-15

    Highlights: • Bacterial extracelluar enzymes stabilized the silver nanoparticles (AgNPs). • AgNPs formation was characterized by analytical techniques such as UV–vis, TEM, and FTIR. • AgNPs showed obvious antimicrobial activity against both gram positive and gram negative microorganisms. • A mechanism of AgNPs’ antimicrobial activity was proposed. -- Abstract: The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO{sub 3} solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV–vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5–50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis.

  17. Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria

    International Nuclear Information System (INIS)

    Tamboli, Dhawal P.; Lee, Dae Sung

    2013-01-01

    Highlights: • Bacterial extracelluar enzymes stabilized the silver nanoparticles (AgNPs). • AgNPs formation was characterized by analytical techniques such as UV–vis, TEM, and FTIR. • AgNPs showed obvious antimicrobial activity against both gram positive and gram negative microorganisms. • A mechanism of AgNPs’ antimicrobial activity was proposed. -- Abstract: The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO 3 solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV–vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5–50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis

  18. Mechanism of action of recombinant acc-royalisin from royal jelly of Asian honeybee against gram-positive bacteria.

    Directory of Open Access Journals (Sweden)

    Lirong Shen

    Full Text Available The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent.

  19. Isolation of highly active monoclonal antibodies against multiresistant gram-positive bacteria.

    Directory of Open Access Journals (Sweden)

    Friederike S Rossmann

    Full Text Available Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA. At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium, a mouse peritonitis model (using S. aureus Newman and LAC and a rat endocarditis model (using E. faecalis 12030 and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials.

  20. Gram-positive bacteria as an antigen topically applied into gingival sulcus of immunized rat accelerates periodontal destruction.

    Science.gov (United States)

    Nagano, F; Kaneko, T; Yoshinaga, Y; Ukai, T; Kuramoto, A; Nakatsu, S; Oshino, K; Ichimura, I; Hara, Y

    2013-08-01

    Periodontitis is generally accepted to relate to gram-negative bacteria, and the host defense system influences its onset and progression. However, little is known about the relation between gram-positive bacteria and periodontitis. In this study, we topically applied gram-positive and gram-negative bacterial suspensions to the gingival sulcus in rats after immunization, and then histopathologically examined their influence on periodontal destruction. Rats previously immunized with heat-treated and sonicated Staphylococcus aureus or Aggregatibacter actinomycetemcomitans were used as immunized groups. The non-immunized group received only sterile phosphate-buffered saline. In each animal, S. aureus or A. actinomycetemcomitans suspension was applied topically to the palatal gingival sulcus of first molars every 24 h for 10 d. Blood samples were collected and the serum level of anti-S. aureus or anti-A. actinomycetemcomitans immunoglobulin G (IgG) antibodies was determined by enzyme-linked immunosorbent assay. The first molar regions were resected and observed histopathologically. Osteoclasts were stained with tartrate-resistant acid phosphatase (TRAP). The formation of immune complexes was confirmed by immunohistological staining of C1qB. Serum levels of anti-S. aureus and anti-A. actinomycetemcomitans IgG antibodies in the immunized groups were significantly higher than those in the non-immunized groups were. The loss of attachment, increase in apical migration of the junctional epithelium, and decreases in alveolar bone level and number of TRAP-positive multinuclear cells in each immunized group were significantly greater than in each non-immunized group. The presence of C1qB was observed in the junctional epithelium and adjacent connective tissue in the immunized groups. Heat-treated and sonicated S. aureus and A. actinomycetemcomitans induced attachment loss in rats immunized with their suspensions. Our results suggest that not only gram-negative but also gram-positive

  1. Bio sorption of some Rare Earth Elements and Yttrium by Gram Positive and Gram Negative Bacteria

    International Nuclear Information System (INIS)

    Ibrahim, H.A.

    2012-01-01

    The separate bio sorption of the REEs La, Sm, Eu and Dy together with yttrium upon the Gram positive bacteria Bacillus subtilis (B.subtilis) and Bacillus Licheniformis (B. Licheniformis),the Gram negative bacterium Escherichia coli (E. coli ) and Saccharomyces cervisiae (Yeast) was studied. The revelant factors of ph 1-6, contact time (30-180 min), the initial rare earth concentration (50-200 mg/l) have been studied. The amount of the accumulated element was strongly affected by its concentration.In addition, bio sorptive fractionation of Y and the studied REEs from a solution containing a mixture of these elements was also studied. From the obtained data, it was found that Langmuir isotherm model for both B.licheniformis and E.coli gives a best fit for the studied elements over the working range of concentration (50-200 mg/I). Transmission electron microscopy exhibited accumulation throughout the bacterial cell with some granular deposits in both the cell periphery and cytoplasm

  2. Revised mechanism of d-alanine incorporation into cell wall polymers in Gram-positive bacteria

    Science.gov (United States)

    Reichmann, Nathalie T.; Cassona, Carolina Picarra

    2013-01-01

    Teichoic acids (TAs) are important for growth, biofilm formation, adhesion and virulence of Gram-positive bacterial pathogens. The chemical structures of the TAs vary between bacteria, though they typically consist of zwitterionic polymers that are anchored to either the peptidoglycan layer as in the case of wall teichoic acid (WTA) or the cell membrane and named lipoteichoic acid (LTA). The polymers are modified with d-alanines and a lack of this decoration leads to increased susceptibility to cationic antimicrobial peptides. Four proteins, DltA–D, are essential for the incorporation of d-alanines into cell wall polymers and it has been established that DltA transfers d-alanines in the cytoplasm of the cell onto the carrier protein DltC. However, two conflicting models have been proposed for the remainder of the mechanism. Using a cellular protein localization and membrane topology analysis, we show here that DltC does not traverse the membrane and that DltD is anchored to the outside of the cell. These data are in agreement with the originally proposed model for d-alanine incorporation through a process that has been proposed to proceed via a d-alanine undecaprenyl phosphate membrane intermediate. Furthermore, we found that WTA isolated from a Staphylococcus aureus strain lacking LTA contains only a small amount of d-alanine, indicating that LTA has a role, either direct or indirect, in the efficient d-alanine incorporation into WTA in living cells. PMID:23858088

  3. Antibacterial Activity of Silver-Graphene Quantum Dots Nanocomposites Against Gram-Positive and Gram-Negative Bacteria

    Science.gov (United States)

    Habiba, Khaled (Inventor); Makarov, Vladimir (Inventor); Weiner, Brad R (Inventor); Morell, Gerardo (Inventor)

    2018-01-01

    The invention provides a composite of silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) using pulsed laser synthesis. The nanocomposites were functionalized with polyethylene glycol (PEG). A concentration of 150 .mu.g/mL of Ag-GQDs, a non-toxic level for human cells, exhibits strong antibacterial activity against both Gram-Positive and Gram-Negative Bacteria.

  4. Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes

    Science.gov (United States)

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

  5. A Flexible Binding Site Architecture Provides New Insights into CcpA Global Regulation in Gram-Positive Bacteria.

    Science.gov (United States)

    Yang, Yunpeng; Zhang, Lu; Huang, He; Yang, Chen; Yang, Sheng; Gu, Yang; Jiang, Weihong

    2017-01-24

    Catabolite control protein A (CcpA) is the master regulator in Gram-positive bacteria that mediates carbon catabolite repression (CCR) and carbon catabolite activation (CCA), two fundamental regulatory mechanisms that enable competitive advantages in carbon catabolism. It is generally regarded that CcpA exerts its regulatory role by binding to a typical 14- to 16-nucleotide (nt) consensus site that is called a catabolite response element (cre) within the target regions. However, here we report a previously unknown noncanonical flexible architecture of the CcpA-binding site in solventogenic clostridia, providing new mechanistic insights into catabolite regulation. This novel CcpA-binding site, named cre var , has a unique architecture that consists of two inverted repeats and an intervening spacer, all of which are variable in nucleotide composition and length, except for a 6-bp core palindromic sequence (TGTAAA/TTTACA). It was found that the length of the intervening spacer of cre var can affect CcpA binding affinity, and moreover, the core palindromic sequence of cre var is the key structure for regulation. Such a variable architecture of cre var shows potential importance for CcpA's diverse and fine regulation. A total of 103 potential cre var sites were discovered in solventogenic Clostridium acetobutylicum, of which 42 sites were picked out for electrophoretic mobility shift assays (EMSAs), and 30 sites were confirmed to be bound by CcpA. These 30 cre var sites are associated with 27 genes involved in many important pathways. Also of significance, the cre var sites are found to be widespread and function in a great number of taxonomically different Gram-positive bacteria, including pathogens, suggesting their global role in Gram-positive bacteria. In Gram-positive bacteria, the global regulator CcpA controls a large number of important physiological and metabolic processes. Although a typical consensus CcpA-binding site, cre, has been identified, it remains

  6. In vitro ciprofloxacin resistance patterns of gram positive bacteria isolated from clinical specimens in a teaching hospital in Saudi Arabia

    International Nuclear Information System (INIS)

    Akhtar, N.; Alzahrani, A.; Obeid, O.El-Treify; Dassal, D.

    2009-01-01

    Over the last few decades the ever-increasing level of bacterial resistance to antimicrobials has been a cause of worldwide concern. Fluoroquinolones, particularly ciprofloxacin has been used indiscriminately for both gram-positive and gram-negative bacterial infections. The increased use of ciprofloxacin has led to a progressive loss of bacterial susceptibility to this antibiotic. Therefore it is necessary to have update knowledge of resistance pattern of bacteria to this antibiotic so that alternate appropriate antibiotics can be used for ciprofloxacin-resistant bacterial infections. Objective: To evaluate the trends of ciprofloxacin resistance pattern in commonly isolated gram positive bacteria over time in a Saudi Arabian teaching hospital. Methods: A retrospective analysis was carried out for ciprofloxacin susceptibility patterns of 5534 isolates of gram-positive bacteria isolated from clinical specimens submitted to microbiology laboratories at King Fahd Hospital of the University (KFHU), Al-Khobar, Saudi Arabia during the period from January 2002 to August 2005. Results: Increase in ciprofloxacin resistance rates with some fluctuations, among these isolates, were observed. For Staphylococcus aureus, it varied from 4.62, 1.83, 7.01 and 3.98%, methicillin resistant Staphylococcus aureus (MRSA) 97.92, 97.75, 87.01 and 88.26%, Streptococcus pyogenes 5.35, 4.47, 14.44 and 3.53% during the years 2002, 2003, 2004 and 2005 respectively. Cirprofloxacin resistance during the years 2002, 2004 and 2005 for other isolates was as follows: Streptococcus pneumoniae, 30.23, 23.02 and 26.47%; enterococcus group D, 43.05, 20.68 and 57.03% and non-enterococcus group D, 62.96, 76.92 and 87.50% respectively. Conclusion: Ciprofloxacin resistance in gram positive bacterial clinical isolates particularly Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA) enterococcus group D, and non-enterococcus group D, has greatly increased and ciprofloxacin no more remains

  7. Desulfotomaculum spp. and related Gram-positive sulfate-reducing bacteria in deep subsurface environments.

    Directory of Open Access Journals (Sweden)

    Thomas eAullo

    2013-12-01

    Full Text Available Gram-positive spore-forming sulfate reducers and particularly members of the genus Desulfotomaculum are commonly found in the subsurface biosphere by culture based and molecular approaches. Due to their metabolic versatility and their ability to persist as endospores. Desulfotomaculum spp. are well adapted for colonizing environments through a slow sedimentation process. Because of their ability to grow autotrophically (H2/CO2 and produce sulfide or acetate, these microorganisms may play key roles in deep lithoautotrophic microbial communities. Available data about Desulfotomaculum spp. and related species from studies carried out from deep freshwater lakes, marine sediments, oligotrophic and organic rich deep geological settings are discussed in this review.

  8. Secretory phospholipase A2 in dromedary tears: a host defense against staphylococci and other gram-positive bacteria.

    Science.gov (United States)

    Ben Bacha, Abir; Abid, Islem

    2013-03-01

    The best known physiologic function of secreted phospholipase A2 (sPLA2) group IIA (sPLA2-IIA) is defense against bacterial infection through hydrolytic degradation of bacterial membrane phospholipids. In fact, sPLA2-IIA effectively kills Gram-positive bacteria and to a lesser extent Gram-negative bacteria and is considered a major component of the eye's innate immune defense system. The antibacterial properties of sPLA2 have been demonstrated in rabbit and human tears. In this report, we have analyzed the bactericidal activity of dromedary tears and the subsequently purified sPLA2 on several Gram-positive bacteria. Our results showed that the sPLA2 displays a potent bactericidal activity against all the tested bacteria particularly against the Staphylococcus strains when tested in the ionic environment of tears. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2. Interestingly, lysozyme purified from dromedary tears showed a significant bactericidal activity against Listeria monocytogene and Staphylococcus epidermidis, whereas the one purified from human tears displayed no activity against these two strains. We have also demonstrated that Ca(2+) is crucial for the activity of dromedary tear sPLA2 and to a less extent Mg(2+) ions. Given the presence of sPLA2 in tears and intestinal secretions, this enzyme may play a substantial role in innate mucosal and systemic bactericidal defenses against Gram-positive bacteria.

  9. New and improved? A review of novel antibiotics for Gram-positive bacteria.

    Science.gov (United States)

    Abbas, M; Paul, M; Huttner, A

    2017-10-01

    The number of antibiotics in the pipeline targeting Gram-positive pathogens has increased in recent years. This narrative review aims to provide a summary of existing evidence on efficacy, microbiological spectrum and safety of novel systemic antibiotics that have either recently been licensed or completed phase III trials, and possess activity predominantly against Gram-positive organisms. A review of the published literature via the MEDLINE database was performed. In addition, ongoing trials were identified through a search of the clinical trial registration platform clinicaltrials.gov, and when necessary, pharmaceutical companies responsible for the development of the drug were contacted for further information. Data on development, microbiological spectrum, pharmacokinetic/pharmacodynamic properties, clinical efficacy, safety and cost are presented for the new cephalosporins ceftaroline and ceftobiprole; the lipoglycopeptides dalbavancin, oritavancin and telavancin; the fluoroquinolones delafloxacin, nemonoxacin and zabofloxacin; the dihydrofolate-reductase inhibitor iclaprim; the pleuromutilin lefamulin; and the tetracycline omadacycline. Although promising, these new antibiotics have so far been tested in non-severe infections whose treatment is generally uncomplicated and whose aetiologies were not predominantly multidrug-resistant pathogens. None of the new antibiotics have shown superiority to standard care, and none have been investigated for patient-relevant outcomes. Safety and pharmacokinetic data continue to be lacking. How these new drugs are to be integrated into the current armamentarium remains to be established. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  10. Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria

    Science.gov (United States)

    Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

    2013-01-01

    Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50 μL leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

  11. Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L. on Two Gram-Negative and Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Bipul Biswas

    2013-01-01

    Full Text Available Aim. To determine the antimicrobial potential of guava (Psidium guajava leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water. The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50 μL leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties.

  12. Miniaturized bead-beating device to automate full DNA sample preparation processes for gram-positive bacteria.

    Science.gov (United States)

    Hwang, Kyu-Youn; Kwon, Sung Hong; Jung, Sun-Ok; Lim, Hee-Kyun; Jung, Won-Jong; Park, Chin-Sung; Kim, Joon-Ho; Suh, Kahp-Yang; Huh, Nam

    2011-11-07

    We have developed a miniaturized bead-beating device to automate nucleic acids extraction from Gram-positive bacteria for molecular diagnostics. The microfluidic device was fabricated by sandwiching a monolithic flexible polydimethylsiloxane (PDMS) membrane between two glass wafers (i.e., glass-PDMS-glass), which acted as an actuator for bead collision via its pneumatic vibration without additional lysis equipment. The Gram-positive bacteria, S. aureus and methicillin-resistant S. aureus, were captured on surface-modified glass beads from 1 mL of initial sample solution and in situ lyzed by bead-beating operation. Then, 10 μL or 20 μL of bacterial DNA solution was eluted and amplified successfully by real-time PCR. It was found that liquid volume fraction played a crucial role in determining the cell lysis efficiency in a confined chamber by facilitating membrane deflection and bead motion. The miniaturized bead-beating operation disrupted most of S. aureus within 3 min, which turned out to be as efficient as the conventional benchtop vortexing machine or the enzyme-based lysis technique. The effective cell concentration was significantly enhanced with the reduction of initial sample volume by 50 or 100 times. Combination of such analyte enrichment and in situ bead-beating lysis provided an excellent PCR detection sensitivity amounting to ca. 46 CFU even for the Gram-positive bacteria. The proposed bead-beating microdevice is potentially useful as a nucleic acid extraction method toward a PCR-based sample-to-answer system. This journal is © The Royal Society of Chemistry 2011

  13. A Flexible Binding Site Architecture Provides New Insights into CcpA Global Regulation in Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Yunpeng Yang

    2017-01-01

    Full Text Available Catabolite control protein A (CcpA is the master regulator in Gram-positive bacteria that mediates carbon catabolite repression (CCR and carbon catabolite activation (CCA, two fundamental regulatory mechanisms that enable competitive advantages in carbon catabolism. It is generally regarded that CcpA exerts its regulatory role by binding to a typical 14- to 16-nucleotide (nt consensus site that is called a catabolite response element (cre within the target regions. However, here we report a previously unknown noncanonical flexible architecture of the CcpA-binding site in solventogenic clostridia, providing new mechanistic insights into catabolite regulation. This novel CcpA-binding site, named crevar, has a unique architecture that consists of two inverted repeats and an intervening spacer, all of which are variable in nucleotide composition and length, except for a 6-bp core palindromic sequence (TGTAAA/TTTACA. It was found that the length of the intervening spacer of crevar can affect CcpA binding affinity, and moreover, the core palindromic sequence of crevar is the key structure for regulation. Such a variable architecture of crevar shows potential importance for CcpA’s diverse and fine regulation. A total of 103 potential crevar sites were discovered in solventogenic Clostridium acetobutylicum, of which 42 sites were picked out for electrophoretic mobility shift assays (EMSAs, and 30 sites were confirmed to be bound by CcpA. These 30 crevar sites are associated with 27 genes involved in many important pathways. Also of significance, the crevar sites are found to be widespread and function in a great number of taxonomically different Gram-positive bacteria, including pathogens, suggesting their global role in Gram-positive bacteria.

  14. Characterization and Discrimination of Gram-Positive Bacteria Using Raman Spectroscopy with the Aid of Principal Component Analysis

    Directory of Open Access Journals (Sweden)

    Alia Colniță

    2017-09-01

    Full Text Available Raman scattering and its particular effect, surface-enhanced Raman scattering (SERS, are whole-organism fingerprinting spectroscopic techniques that gain more and more popularity in bacterial detection. In this work, two relevant Gram-positive bacteria species, Lactobacillus casei (L. casei and Listeria monocytogenes (L. monocytogenes were characterized based on their Raman and SERS spectral fingerprints. The SERS spectra were used to identify the biochemical structures of the bacterial cell wall. Two synthesis methods of the SERS-active nanomaterials were used and the recorded spectra were analyzed. L. casei and L. monocytogenes were successfully discriminated by applying Principal Component Analysis (PCA to their specific spectral data.

  15. Antibacterial properties of biosurfactants against selected Gram-positive and -negative bacteria.

    Science.gov (United States)

    Díaz De Rienzo, Mayri A; Stevenson, Paul; Marchant, Roger; Banat, Ibrahim M

    2016-01-01

    The antibacterial properties and ability to disrupt biofilms of biosurfactants (rhamnolipids, sophorolipids) and sodium dodecyl sulphate (SDS) in the presence and absence of selected organic acids were investigated. Pseudomonas aeruginosa PAO1 was inhibited by sophorolipids and SDS at concentrations >5% v/v, and the growth of Escherichia coli NCTC 10418 was also inhibited by sophorolipids and SDS at concentrations >5% and 0.1% v/v, respectively. Bacillus subtilis NCTC 10400 was inhibited by rhamnolipids, sophorolipids and SDS at concentrations >0.5% v/v of all three; the same effect was observed with Staphylococcus aureus ATCC 9144. The ability to attach to surfaces and biofilm formation of P. aeruginosa PAO1, E. coli NCTC 10418 and B. subtilis NCTC 10400 was inhibited by sophorolipids (1% v/v) in the presence of caprylic acid (0.8% v/v). In the case of S. aureus ATCC 9144, the best results were obtained using caprylic acid on its own. It was concluded that sophorolipids are promising compounds for the inhibition/disruption of biofilms formed by Gram-positive and Gram-negative microorganisms and this activity can be enhanced by the presence of booster compounds such as caprylic acid. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. Two Cases of Endogenous Endophthalmitis Caused by Gram-Positive Bacteria with Good Visual Outcome

    Directory of Open Access Journals (Sweden)

    Machiko Itoh

    2010-09-01

    Full Text Available Background: Endogenous endophthalmitis is a rare disease and its visual prognosis is poor. Case Reports: We present two patients, a 60-year-old man and a 53-year-old man, who developed endogenous endophthalmitis caused byGram-positive organismsbut recovered good vision after antibiotics and vitrectomy. Results: The first patient complained of ocular pain and visual decrease in his right eye. Ophthalmoscopy showed inflammation in the anterior chamber and vitreous opacities. Antibiotic was administrated systemically, and blood culture detected Streptococcus anginosus. He underwent successful heart surgery for endocarditis and total dental extraction for severe gingivitis. Vitrectomy was performed 36 days after the onset and vision improved from 0.02 to 0.7. The second patient was referred for acute visual decrease in his left eye. Severe iritis and vitreous opacities were observed, and systemic examination showed acute pyelitis and prostatic abscesses. Blood cultures detected Staphylococcus sp., and systemic antibiotics were given. Vitrectomy was performed 12 days after the onset, and vision improved from 0.06 to 1.2. Conclusions: We conclude that the rapid treatment with systemic antibiotics for the organisms at the primary site, and the vitrectomy, even though delayed, can lead to a good recovery of vision.

  17. Antibacterial activity of oregano (Origanum vulgare Linn.) against gram positive bacteria.

    Science.gov (United States)

    Saeed, Sabahat; Tariq, Perween

    2009-10-01

    The present investigation is focused on antibacterial potential of infusion, decoction and essential oil of oregano (Origanum vulgare) against 111 Gram-positive bacterial isolates belonging to 23 different species related to 3 genera. Infusion and essential oil exhibited antibacterial activity against Staphylococcus saprophyticus, S. aureus, Micrococcus roseus, M. kristinae, M. nishinomiyaensis, M. lylae, M. luteus, M. sedentarius, M. varians, Bacillus megaterium, B. thuringiensis, B. alvei, B. circulans, B. brevis, B. coagulans, B. pumilus, B. laterosporus, B. polymyxa, B. macerans, B. subtilis, B. firmus, B. cereus and B. lichiniformis. The infusion exhibited maximum activity against B. laterosporus (17.5 mm mean zone of inhibition+/-1.5 Standard deviation) followed by B. polymyxa (17.0 mm+/-2.0 SD) and essential oil of oregano exhibited maximum activity against S. saprophyticus (16.8 mm+/-1.8 SD) followed by B. circulans (14.5 mm+/-0.5 SD). While all these tested isolates were found resistant to decoction of oregano.

  18. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria.

    Science.gov (United States)

    Mistou, Michel-Yves; Sutcliffe, Iain C; van Sorge, Nina M

    2016-07-01

    The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. © FEMS 2016.

  19. Microbiological method for radiation sterilization (II). Identification procedure of gram positive bacteria by using BBL CRYSTAL GP identification kit

    International Nuclear Information System (INIS)

    Koshikawa, Tomihiko

    2004-01-01

    The part II in this title series describes details of the commercially available BBL CRYSTAL GP Identification Kit with the software (Becton, Dickinson and Co., Ltd.), by which identification of Gram positive bacteria as well as their number becoming easier in the radiation sterilization of medical devices. Isolation of a bacterium has to be confirmed by microscopy and its Gram positive property, by the Gram staining. The exponentially growing bacteria are to be inoculated in the Kit and cultured for 18-24 hr at 37 deg C with the lid attached by substrates for identification. Reactions to substrates are to be judged by CRYSTAL auto-reader, which is further to be searched by the computer software (code-book) for final identification. For possible misidentification, re-isolation of the bacterium, prolonged culture, concentrated inoculation and re-consideration for ranking of identification the software provides are necessary as well as other identification approaches. Representative bacteria as the bioburden are spp. of Bacilli, Corynebacteria, Staphylococci and Micrococci. (N.I.)

  20. Glycosaminoglycans are involved in pathogen adherence to corneal epithelial cells differently for Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Beatriz García

    2016-11-01

    Full Text Available The epithelium of the cornea is continuously exposed to pathogens, and adhesion to epithelial cells is regarded as an essential first step in bacterial pathogenesis. In this article, the involvement of glycosaminoglycans in the adhesion of various pathogenic bacteria to corneal epithelial cells is analyzed. All microorganisms use glycosaminoglycans as receptors, but arranged in different patterns depending on the Gram-type of the bacterium. The heparan sulfate chains of syndecans are the main receptors, though other molecular species also seem to be involved, particularly in Gram-negative bacteria. Adherence is inhibited differentially by peptides, including heparin binding sequences, indicating the participation of various groups of Gram-positive and -negative adhesins. The length of the saccharides produces a major effect, and low molecular weight chains inhibit the binding of Gram-negative microorganisms but increase the adherence of Gram-positives. Pathogen adhesion appears to occur preferentially through sulfated domains, and is very dependent on N- and 6-O-sulfation of the glucosamine residue and, to a lesser extent, 2-O sulfation of uronic acid. These data show the differential use of corneal receptors, which could facilitate the development of new anti-infective strategies.

  1. A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria

    Science.gov (United States)

    Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Íñigo; Novick, Richard P.; Christie, Gail E.; Penadés, José R.

    2013-01-01

    The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria. PMID:23771138

  2. Crystallization and preliminary X-ray analysis of three dUTPases from Gram-positive bacteria

    International Nuclear Information System (INIS)

    Li, Gui-Lan; Wang, Juan; Li, Lan-Fen; Su, Xiao-Dong

    2009-01-01

    All organisms examined to date possess a dUTPase that performs the important function of efficiently hydrolyzing dUTP to dUMP in order to prevent the incorporation of dUTP into DNA. Three putative dUTPases from Gram-positive bacteria have been studied in this work. All organisms examined to date possess a dUTPase that performs the important function of efficiently hydrolyzing dUTP to dUMP in order to prevent the incorporation of dUTP into DNA. Three putative dUTPases from Gram-positive bacteria have been studied in this work. Two dUTPase-encoding genes, yncF and yosS, have been identified in Bacillus subtilis. The gene dut, encoding dUTPase from the dental pathogen Streptococcus mutans, was amplified from S. mutans genomic DNA. The three genes were cloned into expression vectors and overexpressed at high levels in Escherichia coli. Each protein was purified in two steps using chromatographic methods. Crystals of the YosS and YncF proteins and of S. mutans dUTPase were obtained using the vapour-diffusion method. X-ray diffraction data sets were collected from crystals of selenomethionine-labelled YosS and S. mutans dUTPase to resolutions of 2.3 and 1.7 Å, respectively. The crystal of native YncF diffracted to 2.7 Å resolution

  3. Cardiolipin, a major phospholipid of gram-positive bacteria that is not readily extractable

    NARCIS (Netherlands)

    Filgueiras, M.H.; Kamp, J.A.F. op den

    1980-01-01

    Extraction of phospholipids from stationary phase grown cells of the Gram+ bacteria, Bacillus megaterium, Bacillus subtilis, Bacillus cereus and Micrococcus lysodeikticus was found to be incomplete with various commonly used extraction procedures. Phosphatidylglycerol and phosphatidyl-ethanolamine

  4. Evaluation of the Verigene Gram-positive blood culture nucleic acid test for rapid detection of bacteria and resistance determinants.

    Science.gov (United States)

    Wojewoda, Christina M; Sercia, Linda; Navas, Maria; Tuohy, Marion; Wilson, Deborah; Hall, Geraldine S; Procop, Gary W; Richter, Sandra S

    2013-07-01

    Rapid identification of pathogens from blood cultures can decrease lengths of stay and improve patient outcomes. We evaluated the accuracy of the Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (Nanosphere, Inc., Northbrook, IL) for the identification of Gram-positive bacteria from blood cultures. The detection of resistance genes (mecA in Staphylococcus aureus and Staphylococcus epidermidis and vanA or vanB in Enterococcus faecium and Enterococcus faecalis) by the BC-GP assay also was assessed. A total of 186 positive blood cultures (in BacT/Alert FA bottles) with Gram-positive cocci observed with Gram staining were analyzed using the BC-GP assay. The BC-GP results were compared with the identification and susceptibility profiles obtained with routine methods in the clinical laboratory. Discordant results were arbitrated with additional biochemical, cefoxitin disk, and repeat BC-GP testing. The initial BC-GP organism identification was concordant with routine method results for 94.6% of the blood cultures. Only 40% of the Streptococcus pneumoniae identifications were correct. The detection of the mecA gene for 69 blood cultures with only S. aureus or S. epidermidis was concordant with susceptibility testing results. For 3 of 6 cultures with multiple Staphylococcus spp., mecA detection was reported but was correlated with oxacillin resistance in a species other than S. aureus or S. epidermidis. The detection of vanA agreed with susceptibility testing results for 45 of 46 cultures with E. faecalis or E. faecium. Comparison of the mean times to results for each organism group showed that BC-GP results were available 31 to 42 h earlier than phenotypic identifications and 41 to 50 h earlier than susceptibility results.

  5. Plants used in Guatemala for the treatment of respiratory diseases. 1. Screening of 68 plants against gram-positive bacteria.

    Science.gov (United States)

    Caceres, A; Alvarez, A V; Ovando, A E; Samayoa, B E

    1991-02-01

    Respiratory ailments are important causes of morbidity and mortality in developing countries. Ethnobotanical surveys and literature reviews conducted in Guatemala during 1986-88 showed that 234 plants from 75 families, most of them of American origin, have been used for the treatment of respiratory ailments. Three Gram-positive bacteria causing respiratory infections (Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) were used to screen 68 of the most commonly used plants for activity. Twenty-eight of these (41.2%) inhibited the growth of one or more of the bacteria tested. Staphylococcus aureus was inhibited by 18 of the plant extracts, while 7 extracts were effective against Streptococcus pyogenes. Plants of American origin which exhibited antibacterial activity were: Gnaphalium viscosum, Lippia alba, Lippia dulcis, Physalis philadelphica, Satureja brownei, Solanum nigrescens and Tagetes lucida. These preliminary in vitro results provide scientific basis for the use of these plants against bacterial respiratory infections.

  6. Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

    Directory of Open Access Journals (Sweden)

    Azam A

    2012-12-01

    Full Text Available Ameer Azam,1,2 Arham S Ahmed,2 Mohammad Oves,3 Mohammad S Khan,3 Sami S Habib,1 Adnan Memic11Centre of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia; 2Centre of Excellence in Materials Science (Nanomaterials, 3Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh, IndiaBackground: Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria.Methods and results: Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3 were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa and Gram-positive (Staphylococcus aureus and Bacillus subtilis bacteria.Conclusion: Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3

  7. Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment.

    Science.gov (United States)

    Lemmen, S W; Häfner, H; Zolldann, D; Stanzel, S; Lütticken, R

    2004-03-01

    We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (PGram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (PGram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources.

  8. Hyperspectral microscope imaging methods to classify gram-positive and gram-negative foodborne pathogenic bacteria

    Science.gov (United States)

    An acousto-optic tunable filter-based hyperspectral microscope imaging method has potential for identification of foodborne pathogenic bacteria from microcolony rapidly with a single cell level. We have successfully developed the method to acquire quality hyperspectral microscopic images from variou...

  9. Classification of gram-positive and gram-negative foodborne pathogenic bacteria with hyperspectral microscope imaging

    Science.gov (United States)

    Optical method with hyperspectral microscope imaging (HMI) has potential for identification of foodborne pathogenic bacteria from microcolonies rapidly with a cell level. A HMI system that provides both spatial and spectral information could be an effective tool for analyzing spectral characteristic...

  10. The Role of Functional Amyloids in Multicellular Growth and Development of Gram-Positive Bacteria

    NARCIS (Netherlands)

    Dragoš, A.; Kovács, Á.T.; Claessen, D.

    2017-01-01

    Amyloid fibrils play pivotal roles in all domains of life. In bacteria, these fibrillar structures are often part of an extracellular matrix that surrounds the producing organism and thereby provides protection to harsh environmental conditions. Here, we discuss the role of amyloid fibrils in the

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

    Science.gov (United States)

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

    2002-04-01

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

  12. Activity of siderophores against drug-resistant Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Gokarn K

    2018-01-01

    Full Text Available Karuna Gokarn,1,2 Ramprasad B Pal1 1Department of Microbiology, Sir Hurkisondas Nurrotumdas Medical Research Society, 2Caius Research Laboratory, St Xavier’s College, Mumbai, India Abstract: Infections by drug-resistant bacteria are life-threatening. As iron is a vital element for the growth of bacteria, iron-chelating agents (siderophores can be used to arrest their multiplication. Exogenous siderophores – exochelin-MS and deferoxamine-B – were evaluated for their inhibitory activity against methicillin-resistant Staphylococcus aureus and metallo-β-lactamase producers – Pseudomonas aeruginosa and Acinetobacter baumannii – by disc diffusion, micro-broth dilution, and turbidimetric growth assays. The drug-resistant isolates were inhibited by the synergistic activity of siderophores and antibiotics. Minimum inhibitory concentration of exochelin-MS+ampicillin for different isolates was between 0.05 and 0.5 mg/mL. Minimum inhibitory concentration of deferoxamine-B+ampicillin was 1.0 mg/mL and greater. Iron-chelation therapy could provide a complementary approach to overcome drug resistance in pathogenic bacteria. Keywords: iron-chelation, xenosiderophores, exochelin MS, deferoxamine B

  13. Inhibition of various gram-positive and gram-negative bacteria growth on selenium nanoparticle coated paper towels.

    Science.gov (United States)

    Wang, Qi; Larese-Casanova, Philip; Webster, Thomas J

    2015-01-01

    There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns.

  14. Distinction of Gram-positive and -negative bacteria using a colorimetric microbial viability assay based on the reduction of water-soluble tetrazolium salts with a selection medium.

    Science.gov (United States)

    Tsukatani, Tadayuki; Suenaga, Hikaru; Higuchi, Tomoko; Shiga, Masanobu; Noguchi, Katsuya; Matsumoto, Kiyoshi

    2011-01-01

    Bacteria are fundamentally divided into two groups: Gram-positive and Gram-negative. Although the Gram stain and other techniques can be used to differentiate these groups, some issues exist with traditional approaches. In this study, we developed a method for differentiating Gram-positive and -negative bacteria using a colorimetric microbial viability assay based on the reduction of the tetrazolium salt {2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt} (WST-8) via 2-methyl-1,4-napthoquinone with a selection medium. We optimized the composition of the selection medium to allow the growth of Gram-negative bacteria while inhibiting the growth of Gram-positive bacteria. When the colorimetric viability assay was carried out in a selection medium containing 0.5µg/ml crystal violet, 5.0 µg/ml daptomycin, and 5.0µg/ml vancomycin, the reduction in WST-8 by Gram-positive bacteria was inhibited. On the other hand, Gram-negative bacteria produced WST-8-formazan in the selection medium. The proposed method was also applied to determine the Gram staining characteristics of bacteria isolated from various foodstuffs. There was good agreement between the results obtained using the present method and those obtained using a conventional staining method. These results suggest that the WST-8 colorimetric assay with selection medium is a useful technique for accurately differentiating Gram-positive and -negative bacteria.

  15. How bacterial cell division might cheat turgor pressure - a unified mechanism of septal division in Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Erickson, Harold P

    2017-08-01

    An important question for bacterial cell division is how the invaginating septum can overcome the turgor force generated by the high osmolarity of the cytoplasm. I suggest that it may not need to. Several studies in Gram-negative bacteria have shown that the periplasm is isoosmolar with the cytoplasm. Indirect evidence suggests that this is also true for Gram-positive bacteria. In this case the invagination of the septum takes place within the uniformly high osmotic pressure environment, and does not have to fight turgor pressure. A related question is how the V-shaped constriction of Gram-negative bacteria relates to the plate-like septum of Gram-positive bacteria. I collected evidence that Gram-negative bacteria have a latent capability of forming plate-like septa, and present a model in which septal division is the basic mechanism in both Gram-positive and Gram-negative bacteria. © 2017 WILEY Periodicals, Inc.

  16. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    Science.gov (United States)

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  17. Rapid and reliable identification of Gram-negative bacteria and Gram-positive cocci by deposition of bacteria harvested from blood cultures onto the MALDI-TOF plate.

    Science.gov (United States)

    Barnini, Simona; Ghelardi, Emilia; Brucculeri, Veronica; Morici, Paola; Lupetti, Antonella

    2015-06-18

    Rapid identification of the causative agent(s) of bloodstream infections using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) methodology can lead to increased empirical antimicrobial therapy appropriateness. Herein, we aimed at establishing an easier and simpler method, further referred to as the direct method, using bacteria harvested by serum separator tubes from positive blood cultures and placed onto the polished steel target plate for rapid identification by MALDI-TOF. The results by the direct method were compared with those obtained by MALDI-TOF on bacteria isolated on solid media. Identification of Gram-negative bacilli was 100 % concordant using the direct method or MALDI-TOF on isolated bacteria (96 % with score > 2.0). These two methods were 90 % concordant on Gram-positive cocci (32 % with score > 2.0). Identification by the SepsiTyper method of Gram-positive cocci gave concordant results with MALDI-TOF on isolated bacteria in 87 % of cases (37 % with score > 2.0). The direct method herein developed allows rapid identification (within 30 min) of Gram-negative bacteria and Gram-positive cocci from positive blood cultures and can be used to rapidly report reliable and accurate results, without requiring skilled personnel or the use of expensive kits.

  18. Antibacterial activity of sphingoid bases and fatty acids against Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Fischer, Carol L; Drake, David R; Dawson, Deborah V; Blanchette, Derek R; Brogden, Kim A; Wertz, Philip W

    2012-03-01

    There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity--the sphingoid bases D-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid--against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P 500 μg/ml). Sapienic acid (MBC range, 31.3 to 375.0 μg/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 μg/ml). Lauric acid (MBC range, 6.8 to 375.0 μg/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 μg/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection.

  19. Novel Group of Leaderless Multipeptide Bacteriocins from Gram-Positive Bacteria.

    Science.gov (United States)

    Ovchinnikov, Kirill V; Chi, Hai; Mehmeti, Ibrahim; Holo, Helge; Nes, Ingolf F; Diep, Dzung B

    2016-09-01

    -resistant bacteria, but the number of bacteriocins with very broad antimicrobial spectra is very small. In this study, we have found and purified a novel three-peptide bacteriocin, garvicin KS. By homology search, we were able to find one known and three novel sequence-related bacteriocins consisting of 3 or 4 peptides. None of the peptides has modified amino acids in its sequence. Thus, the activity of all bacteriocins was confirmed with chemically synthesized peptides. All of them, especially garvicin KS, have very broad antibacterial spectra, thus representing a great potential in antimicrobial applications in the food industry and medicine. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  20. Nanoparticle targeting of Gram-positive and Gram-negative bacteria for magnetic-based separations of bacterial pathogens

    Science.gov (United States)

    Lu, Hoang D.; Yang, Shirley S.; Wilson, Brian K.; McManus, Simon A.; Chen, Christopher V. H.-H.; Prud'homme, Robert K.

    2017-04-01

    Antimicrobial resistance is a healthcare problem of increasing significance, and there is increasing interest in developing new tools to address bacterial infections. Bacteria-targeting nanoparticles hold promise to improve drug efficacy, compliance, and safety. In addition, nanoparticles can also be used for novel applications, such as bacterial imaging or bioseperations. We here present the use of a scalable block-copolymer-directed self-assembly process, Flash NanoPrecipitation, to form zinc(II)-bis(dipicolylamine) modified nanoparticles that bind to both Gram-positive and Gram-negative bacteria with specificity. Particles have tunable surface ligand densities that change particle avidity and binding efficacy. A variety of materials can be encapsulated into the core of the particles, such as optical dyes or iron oxide colloids, to produce imageable and magnetically active bacterial targeting constructs. As a proof-of-concept, these particles are used to bind and separate bacteria from solution in a magnetic column. Magnetic manipulation and separation would translate to a platform for pathogen identification or removal. These magnetic and targeted nanoparticles enable new methods to address bacterial infections.

  1. Endophthalmitis caused by gram-positive bacteria resistant to vancomycin: Clinical settings, causative organisms, antimicrobial susceptibilities, and treatment outcomes

    Directory of Open Access Journals (Sweden)

    Hegde Sharat Shivaramaiah

    2018-06-01

    Full Text Available Purpose: To report the clinical settings, causative organisms, antimicrobial susceptibilities, and treatment outcomes of patients with endophthalmitis caused by gram-positive bacteria resistant to vancomycin. Methods: Retrospective case series of all patients with culture-proven endophthalmitis caused by gram-positive bacteria resistant to vancomycin between January 2010 and December 2016 in LV Prasad Eye Institute, Visakhapatnam, India. Results: The current study included 14 patients. The clinical settings were post-cataract surgery in 8/14 (57.1% and open globe injury in 6/14 (42.8%. Primary intervention for all patients included tap and intravitreal antibiotic injection. During subsequent follow-up, pars plana vitrectomy was performed in 6 patients and one patient underwent penetrating keratoplasty. Mean number of intravitreal antibiotic injections performed were 3.4 per patient. The most common organisms isolated were coagulase-negative Staphylococci in 6/14 (42.8%, Staphylococcus aureus in 5/14 (35.7%, Streptococcus sp in 2/14 (14.2% and Bacillus sp in 1/14 (7.14%. In addition to vancomycin, resistance to multiple drugs (three or more groups of antibiotics was found in all 14 cases. Antimicrobial susceptibility results showed susceptibility to amikacin in 7/14 (50.0%, gatifloxacin in 6/14 (42.8%, moxifloxacin in 3/13 (23.0%, cefazoline in 5/14 (35.7%, cefuroxime in 3/14 (21.4%, ciprofloxacin in 2/14 (14.2% and linezolid in 5/5 (100%. The mean duration of follow-up was 30.7 weeks (6 weeks–90 weeks. At last follow-up, visual acuity (VA of 20/200 or better was recorded in 7/14 (50% and VA < 5/200 occurred in 7/14 (50%. Conclusion and importance: Antimicrobial susceptibility testing may help in selection of suitable antimicrobial agents for repeat intravitreal injection. Inspite of retreatment with intravitreal antibiotics, these patients generally had poor VA outcomes. Keywords: Coagulase-negative Staphylococci, Endophthalmitis

  2. Antibacterial activity and interactions of plant essential oil combinations against Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Cristina Anamaria Semeniuc

    2017-04-01

    Full Text Available The aim of this study was to compare the antibacterial effects of several essential oils (EOs alone and in combination against different Gram-positive and Gram-negative bacteria associated with food products. Parsley, lovage, basil, and thyme EOs, as well as their mixtures (1:1, v/v, were tested against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium. The inhibitory effects ranged from strong (thyme EO against E. coli to no inhibition (parsley EO against P. aeruginosa. Thyme EO exhibited strong (against E. coli, moderate (against S. typhimurium and B. cereus, or mild inhibitory effects (against P. aeruginosa and S. aureus, and basil EO showed mild (against E. coli and B. cereus or no inhibitory effects (against S. typhimurium, P. aeruginosa, and S. aureus. Parsley and lovage EOs revealed no inhibitory effects against all tested strains. Combinations of lovage/thyme and basil/thyme EOs displayed antagonistic effects against all bacteria, parsley/thyme EOs against B. cereus, S. aureus, P. aeruginosa, and E. coli, and lovage/basil EOs against B. cereus and E. coli. Combinations of parsley/lovage and parsley/basil EOs exhibited indifferent effects against all bacteria. The combination of lovage/basil EO showed indifferent effect against S. aureus, P. aeruginosa, and S. typhimurium, and the combination parsley/thyme EO against S. typhimurium. Thyme EO has the highest percentage yield and antibacterial potential from all tested formulations; its combination with parsley, lovage, and basil EOs determines a reduction of its antibacterial activity. Hence, it is recommended to be used alone as the antibacterial agent.

  3. Dose-Dependent Antimicrobial Activity of Silver Nanoparticles on Polycaprolactone Fibers against Gram-Positive and Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Erick Pazos-Ortiz

    2017-01-01

    Full Text Available The adhesion ability and adaptability of bacteria, coupled with constant use of the same bactericides, have made the increase in the diversity of treatments against infections necessary. Nanotechnology has played an important role in the search for new ways to prevent and treat infections, including the use of metallic nanoparticles with antibacterial properties. In this study, we worked on the design of a composite of silver nanoparticles (AgNPS embedded in poly-epsilon-caprolactone nanofibers and evaluated its antimicrobial properties against various Gram-positive and Gram-negative microorganisms associated with drug-resistant infections. Polycaprolactone-silver composites (PCL-AgNPs were prepared in two steps. The first step consisted in the reduction in situ of Ag+ ions using N,N-dimethylformamide (DMF in tetrahydrofuran (THF solution, and the second step involved the simple addition of polycaprolactone before electrospinning process. Antibacterial activity of PCL-AgNPs nanofibers against E. coli, S. mutans, K. pneumoniae, S. aureus, P. aeruginosa, and B. subtilis was evaluated. Results showed sensibility of E. coli, K. pneumoniae, S. aureus, and P. aeruginosa, but not for B. subtilis and S. mutans. This antimicrobial activity of PCL-AgNPs showed significant positive correlations associated with the dose-dependent effect. The antibacterial property of the PCL/Ag nanofibers might have high potential medical applications in drug-resistant infections.

  4. Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.

    Science.gov (United States)

    Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

    2014-01-01

    Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Antibacterial Activity of Extracellular Protease Isolated From an Algicolous Fungus Xylaria psidii KT30 Against Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Taufik Indarmawan

    2016-04-01

    Full Text Available Infectious diseases became more serious problem for public health in recent years. Although existing antibacterial drugs have been relatively effective, they do not rule out the emergence of resistance to the drug. Therefore, the intensive exploration of new bioactive compounds from natural, especially peptide compounds began in recent decades in order-handling infection. This study aimed to isolate, purify and test the potential application of Xylaria psidii KT30 extracellular protease as antibacterial agent against Gram-positive bacteria. X. psidii KT30, a marine fungus isolated from red seaweed Kappaphycus alvarezii showed antibacterial activity against Bacillus subtilis and Staphylococcus aureus. Antibacterial compounds of this fungus were predicted as a group of proteases. Extracellular protease exhibited an optimum activity when potato dextrose broth was used as cultivation medium. Furthermore, the highest activity of these proteases was found on fungal extract after day 15 of cultivation with value of 2.33 ± 0.19 U/mL. The partial purification of proteases using G-75 column chromatography resulted in 2 groups of fractions and showed protease activity based on zymogram assay. The extracellular proteases obtained from those fractions have 3 patterns of molecular mass based on sodium dodecyl sulfate–polyacrylamide gel electrophoresis which are 56.62, 89.12, 162.18 kDa.

  6. A Sortase A-Immobilized Mesoporous Hollow Carbon Sphere-Based Biosensor for Detection of Gram-Positive Bacteria

    Science.gov (United States)

    Wang, Hongsu; Luo, Ruiping; Chen, Yang; Si, Qi; Niu, Xiaodi

    2018-05-01

    A sensor based on mesoporous carbon materials immobilized with sortase A (SrtA) for determination of Staphylococcus aureus (S. aureus) is reported. To prepare the biosensor, we first synthesized carboxyl-functionalized mesoporous hollow carbon spheres, then applied them as carriers for immobilization of SrtA. Based on the catalytic mechanism of SrtA, a highly sensitive, inexpensive, and rapid method was developed for S. aureus detection. The sensor showed a linear response in the bacterial concentration range of 0.125 × 102 colony-forming units (CFU) mL-1 to 2.5 × 102 CFU mL-1, with detection limit as low as 9.0 CFU mL-1. The method was successfully used for quantitative detection of S. aureus in whole milk samples, giving results similar to experimental results obtained from the plate counting method. This biosensor could also be used to detect other Gram-positive bacteria that secrete SrtA.

  7. Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria

    Science.gov (United States)

    Fröhling, Antje; Schlüter, Oliver

    2015-01-01

    Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfill the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results. The aim of this study was to compare the inactivation effects of peracetic acid (PAA), ozonated water (O3), and cold atmospheric pressure plasma (CAPP) on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s) with 0.25% PAA at 10°C, and after treatment (10 s) with 3.8 mg l−1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l−1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process parameters. PMID

  8. Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Antje eFröhling

    2015-09-01

    Full Text Available Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfil the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results.The aim of this study was to compare the inactivation effects of peracetic acid (PAA, ozonated water (O3 and cold atmospheric pressure plasma (CAPP on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s with 0.25 % PAA at 10 °C, and after treatment (10 s with 3.8 mg l-1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 min and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l-1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process

  9. Type I and Type II mechanisms of antimicrobial photodynamic therapy: an in vitro study on gram-negative and gram-positive bacteria.

    Science.gov (United States)

    Huang, Liyi; Xuan, Yi; Koide, Yuichiro; Zhiyentayev, Timur; Tanaka, Masamitsu; Hamblin, Michael R

    2012-08-01

    Antimicrobial photodynamic therapy (APDT) employs a non-toxic photosensitizer (PS) and visible light, which in the presence of oxygen produce reactive oxygen species (ROS), such as singlet oxygen ((1) O(2), produced via Type II mechanism) and hydroxyl radical (HO(.), produced via Type I mechanism). This study examined the relative contributions of (1) O(2) and HO(.) to APDT killing of Gram-positive and Gram-negative bacteria. Fluorescence probes, 3'-(p-hydroxyphenyl)-fluorescein (HPF) and singlet oxygen sensor green reagent (SOSG) were used to determine HO(.) and (1) O(2) produced by illumination of two PS: tris-cationic-buckminsterfullerene (BB6) and a conjugate between polyethylenimine and chlorin(e6) (PEI-ce6). Dimethylthiourea is a HO(.) scavenger, while sodium azide (NaN(3)) is a quencher of (1) O(2). Both APDT and killing by Fenton reaction (chemical generation of HO(.)) were carried out on Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa). Conjugate PEI-ce6 mainly produced (1) O(2) (quenched by NaN(3)), while BB6 produced HO(.) in addition to (1) O(2) when NaN(3) potentiated probe activation. NaN(3) also potentiated HPF activation by Fenton reagent. All bacteria were killed by Fenton reagent but Gram-positive bacteria needed a higher concentration than Gram-negatives. NaN(3) potentiated Fenton-mediated killing of all bacteria. The ratio of APDT killing between Gram-positive and Gram-negative bacteria was 2 or 4:1 for BB6 and 25:1 for conjugate PEI-ce6. There was a NaN(3) dose-dependent inhibition of APDT killing using both PEI-ce6 and BB6 against Gram-negative bacteria while NaN(3) almost failed to inhibit killing of Gram-positive bacteria. Azidyl radicals may be formed from NaN(3) and HO(.). It may be that Gram-negative bacteria are more susceptible to HO(.) while Gram-positive bacteria are more susceptible to (1) O(2). The differences in Na

  10. Identification of the sigmaB regulon of Bacillus cereus and conservation of sigmaB-regulated genes in low-GC-content gram-positive bacteria

    NARCIS (Netherlands)

    Schaik, van W.; Voort, van der M.; Molenaar, D.; Moezelaar, R.; Vos, de W.M.; Abee, T.

    2007-01-01

    The alternative sigma factor B has an important role in the acquisition of stress resistance in many gram-positive bacteria, including the food-borne pathogen Bacillus cereus. Here, we describe the identification of the set of B-regulated genes in B. cereus by DNA microarray analysis of the

  11. Evolution of Recognition of Ligands from Gram-Positive Bacteria: Similarities and Differences in the TLR2-Mediated Response between Mammalian Vertebrates and Teleost Fish

    NARCIS (Netherlands)

    Ribeiro, Carla M. S.; Hermsen, Trudi; Taverne-Thiele, Anja J.; Savelkoul, Huub F. J.; Wiegertjes, Geert F.

    2010-01-01

    We investigated the role of the TLR2 receptor in the recognition of ligands from Gram-positive bacteria in fish. Comparative sequence analysis showed a highly conserved Toll/IL-1 receptor domain. Although the leucine-rich repeat domain was less conserved, the position of the critical peptidoglycan

  12. Comparative activity of tigecycline and tetracycline on Gram-negative and Gram-positive bacteria revealed by a multicentre study in four North European countries

    DEFF Research Database (Denmark)

    Nilsson, Lennart E; Frimodt-Møller, Niels; Vaara, Martti

    2011-01-01

    This study involves a multicentre surveillance of tigecycline and tetracycline activity against Gram-negative and Gram-positive bacteria from primary care centres (PCCs), general hospital wards (GHWs) and intensive care units (ICUs) in Denmark (n = 9), Finland (n = 10), Norway (n = 7) and Sweden (n...

  13. [Post-marketing surveillance of antibacterial activities of cefozopran against various clinical isolates--I. Gram-positive bacteria].

    Science.gov (United States)

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

    2003-10-01

    As a post-marketing surveillance, the in vitro antibacterial activities of cefozopran (CZOP), an agent of cephems, against various clinical isolates were yearly evaluated and compared with those of other cephems, oxacephems, penicillins, and carbapenems. Changes in the bacterial susceptibility for CZOP were also evaluated with the resistance ratio calculated with breakpoint MIC. Sixteen species (2,363 strains) of Gram-positive bacteria were isolated from the clinical materials annually collected from 1996 to 2001, and consisted of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus epidermidis (MSSE), methicillin-resistant Staphylococcus epidermidis (MRSE), Staphylococcus haemolyticus, Staphylococcus saprophyticus, Enterococcus faecalis, Enterococcus faecium, Enterococcus avium, Streptococcus pyogenes, Streptococcus agalactiae, penicillin-susceptible Streptococcus pneumoniae (PSSP), penicillin-intermediate resistant S. pneumoniae (PISP), penicillin-resistant S. pneumoniae (PRSP), Streptococcus milleri group and Peptostreptococcus spp. The antibacterial activity of CZOP either against MSSA or MSSE was preferable (MIC90: 2 or 0.5 micrograms/mL) and comparable to those of other cephems. CZOP was also effective on MRSE (MIC90: 16 micrograms/mL) but not on MRSA. CZOP and other cephems had low antibacterial activity against S. haemolyticus (MIC90: 64 micrograms/mL). The antibacterial activity of CZOP against S. saprophyticus was comparable to or higher than those of other cephems, but the MIC90 of CZOP in 2001 was higher than those in 1996-2000 (32 vs 1-2 micrograms/mL). The antibacterial activity of CZOP against E. faecalis was comparable to that of cefpirome (CPR; MIC90: 16 micrograms/mL) and higher than those of other cephems. No antibacterial activity of CZOP against E. faecium and E. avium was observed, like other drugs. The antibacterial activity of CZOP against S. pyogenes

  14. Inactivation dynamics of 222 nm krypton-chlorine excilamp irradiation on Gram-positive and Gram-negative foodborne pathogenic bacteria.

    Science.gov (United States)

    Kang, Jun-Won; Kim, Sang-Soon; Kang, Dong-Hyun

    2018-07-01

    The object of this study was to elucidate the bactericidal mechanism of a 222 nm Krypton Chlorine (KrCl) excilamp compared with that of a 254 nm Low Pressure mercury (LP Hg) lamp. The KrCl excilamp had higher bactericidal capacity against Gram-positive pathogenic bacteria (Staphylococcus aureus and L. monocytogenes) and Gram-negative pathogenic bacteria (S. Typhimurium and E. coli O157:H7) than did the LP Hg lamp when cell suspensions in PBS were irradiated with each type of UV lamp. It was found out that the KrCl excilamp induced cell membrane damage as a form of depolarization. From the study of respiratory chain dehydrogenase activity and the lipid peroxidation assay, it was revealed that cell membrane damage was attributed to inactivation of enzymes related to generation of membrane potential and occurrence of lipid peroxidation. Direct absorption of UV radiation which led to photoreaction through formation of an excited state was one of the causes inducing cell damage. Additionally, generation of ROS and thus occurrence of secondary damage can be another cause. The LP Hg lamp only induced damage to DNA but not to other components such as lipids or proteins. This difference was derived from differences of UV radiation absorption by cellular materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Antimicrobial Activity of Carbon Nanoparticles Isolated from Natural Sources against Pathogenic Gram-Negative and Gram-Positive Bacteria

    International Nuclear Information System (INIS)

    Varghese, S.; Jose, S.; Varghese, S.; Kuriakose, S.; Jose, S.

    2013-01-01

    This paper describes the isolation of carbon nanoparticles (CNPs) from kitchen soot, characterization of the CNPs by UV/visible spectroscopy, SEM and XRD, and their antimicrobial action. The antibacterial activity of the isolated carbon nanoparticles was tested against various pathogenic bacterial strains such as Gram-negative Proteus refrigere and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus and Streptococcus haemolyticus. The inhibition zones were measured, and it was found that the carbon nanoparticles isolated from natural sources are active against these Gram-negative and Gram-positive bacterial strains

  16. The Toll pathway underlies host sexual dimorphism in resistance to both Gram-negative and Gram-positive bacteria in mated Drosophila.

    Science.gov (United States)

    Duneau, David F; Kondolf, Hannah C; Im, Joo Hyun; Ortiz, Gerardo A; Chow, Christopher; Fox, Michael A; Eugénio, Ana T; Revah, J; Buchon, Nicolas; Lazzaro, Brian P

    2017-12-21

    Host sexual dimorphism is being increasingly recognized to generate strong differences in the outcome of infectious disease, but the mechanisms underlying immunological differences between males and females remain poorly characterized. Here, we used Drosophila melanogaster to assess and dissect sexual dimorphism in the innate response to systemic bacterial infection. We demonstrated sexual dimorphism in susceptibility to infection by a broad spectrum of Gram-positive and Gram-negative bacteria. We found that both virgin and mated females are more susceptible than mated males to most, but not all, infections. We investigated in more detail the lower resistance of females to infection with Providencia rettgeri, a Gram-negative bacterium that naturally infects D. melanogaster. We found that females have a higher number of phagocytes than males and that ablation of hemocytes does not eliminate the dimorphism in resistance to P. rettgeri, so the observed dimorphism does not stem from differences in the cellular response. The Imd pathway is critical for the production of antimicrobial peptides in response to Gram-negative bacteria, but mutants for Imd signaling continued to exhibit dimorphism even though both sexes showed strongly reduced resistance. Instead, we found that the Toll pathway is responsible for the dimorphism in resistance. The Toll pathway is dimorphic in genome-wide constitutive gene expression and in induced response to infection. Toll signaling is dimorphic in both constitutive signaling and in induced activation in response to P. rettgeri infection. The dimorphism in pathway activation can be specifically attributed to Persephone-mediated immune stimulation, by which the Toll pathway is triggered in response to pathogen-derived virulence factors. We additionally found that, in absence of Toll signaling, males become more susceptible than females to the Gram-positive Enterococcus faecalis. This reversal in susceptibility between male and female Toll

  17. Detection and Antibiotic Susceptibility Pattern of Biofilm Producing Gram Positive and Gram Negative Bacteria Isolated From a Tertiary Care Hospital of Pakistan

    Directory of Open Access Journals (Sweden)

    Iqbal, M.

    2011-01-01

    Full Text Available Microorganisms adhere to non-living material or living tissue, and form biofilms made up of extracellular polymers/slime. Biofilm-associated microorganisms behave differently from free-floating bacteria with respect to growth rates and ability to resist antimicrobial treatments and therefore pose a public health problem. The objective of this study is to detect the prevalence of biofilm producers among Gram positive and Gram negative bacteria isolated from clinical specimens, and to study their antimicrobial susceptibility pattern. The study was carried out from October 2009 to March 2010, at the Department of Microbiology, Army Medical College/ National University of Sciences and Technology (NUST, Rawalpindi, Pakistan. Clinical specimens were received from various wards of a tertiary care hospital. These were dealt by standard microbiological procedures. Gram positive and Gram negative bacteria isolated were subjected to biofilm detection by congo red agar method (CRA. Antimicrobial susceptibility testing of those isolates, which showed positive results (slime production, was done according to the Kirby-Bauer disc diffusion technique. A total of 150 isolates were tested for the production of biofilm/slime. Among them, 81 isolates showed positive results. From these 81, 51 were Gram positive and 30 were Gram negative. All the 81(54% slime producers showed reduced susceptibility to majority of antibiotics. Bacterial biofilms are an important virulence factor associated with chronic nosocomial infection. Detection of biofilm forming organisms can help in appropriate antibiotic choice.

  18. Therapeutic Potential of a Scorpion Venom-Derived Antimicrobial Peptide and Its Homologs Against Antibiotic-Resistant Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Gaomin Liu

    2018-05-01

    Full Text Available The alarming rise in the prevalence of antibiotic resistance among pathogenic bacteria poses a unique challenge for the development of effective therapeutic agents. Antimicrobial peptides (AMPs have attracted a great deal of attention as a possible solution to the increasing problem of antibiotic-resistant bacteria. Marcin-18 was identified from the scorpion Mesobuthus martensii at both DNA and protein levels. The genomic sequence revealed that the marcin-18 coding gene contains a phase-I intron with a GT-AG splice junction located in the DNA region encoding the N-terminal part of signal peptide. The peptide marcin-18 was also isolated from scorpion venom. A protein sequence homology search revealed that marcin-18 shares extremely high sequence identity to the AMPs meucin-18 and megicin-18. In vitro, chemically synthetic marcin-18 and its homologs (meucin-18 and megicin-18 showed highly potent inhibitory activity against Gram-positive bacteria, including some clinical antibiotic-resistant strains. Importantly, in a mouse acute peritonitis model, these peptides significantly decreased the bacterial load in ascites and rescued nearly all mice heavily infected with clinical methicillin-resistant Staphylococcus aureus from lethal bacteremia. Peptides exerted antimicrobial activity via a bactericidal mechanism and killed bacteria through membrane disruption. Taken together, marcin-18 and its homologs have potential for development as therapeutic agents for treating antibiotic-resistant, Gram-positive bacterial infections.

  19. Determination of the irradiation dose for the inhibition (D-10 radiation doses) of some gram negative and gram positive bacteria in peptone saline water

    International Nuclear Information System (INIS)

    Ayhan, H.; Tutluer, H.

    1994-01-01

    Determination of the irradiation dose for the inhibition of some pathogenic bacteria which cause food poisoning and spoilage were aimed. For this purpose, Salmonella typhi, Salmonella typhimurium,Salmonella enteridits,Klebsiella pneumonia, Pseudomonas fluorescence,Proteus vulgaris, Aeromonas hydrophila ,(gram-negative bacteria) and Bacillus cereus, Staphylococcus aureus strain 24,Staphylococcus aureus ATCC 6538 P,Staphylococcus epidermidis strain 115 and Clostridium perfringens A4TTK,(gram-positive bacteria) were used.Sensitivity of above mentioned bacteria to gamma rays (source Cs-137) was examined in saline with 0.1% peptone at different temperatures.Survivor plots (log.10 number of survivors versus dose) were determined by regression analysis of the data.Decimal reduction doses (D values in kGy) were calculated as the slope obtained from the regression analysis

  20. Physico-Chemical-Managed Killing of Penicillin-Resistant Static and Growing Gram-Positive and Gram-Negative Vegetative Bacteria

    Science.gov (United States)

    Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor); Farris, III, Alex F. (Inventor)

    2012-01-01

    Systems and methods for the use of compounds from the Hofmeister series coupled with specific pH and temperature to provide rapid physico-chemical-managed killing of penicillin-resistant static and growing Gram-positive and Gram-negative vegetative bacteria. The systems and methods represent the more general physico-chemical enhancement of susceptibility for a wide range of pathological macromolecular targets to clinical management by establishing the reactivity of those targets to topically applied drugs or anti-toxins.

  1. Facile synthesis of gold nanoparticles on propylamine functionalized SBA-15 and effect of surface functionality of its enhanced bactericidal activity against gram positive bacteria

    International Nuclear Information System (INIS)

    Bhuyan, Diganta; Saikia, Mrinal; Saikia, Lakshi; Gogoi, Animesh; Saikia, Ratul

    2015-01-01

    The facile synthesis of an SBA-15-pr- + NH 3 .Au 0 nano-hybrid material by spontaneous autoreduction of aqueous chloroaurate anions on propylamine functionalized SBA-15 was successfully demonstrated. The as-synthesized SBA-15-pr- + NH 3 .Au 0 nano-hybrid material was well characterized using low and wide angle x-ray diffraction (XRD), N 2 adsorption–desorption isotherms, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX), x-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy and atomic absorption spectroscopy (AAS). The activity of the nano-hybrid material as a potent bactericidal agent was successfully tested against Gram positive/negative bacteria viz. Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The colony killing percentage of Gram positive bacteria was found to be higher than Gram negative bacteria due to the stronger electrostatic interaction between the positively-charged amine functionality of SBA-15 and the negatively charged functionality of the bacterial cell wall. (paper)

  2. Monograph: In vitro efficacy of 30 ethnomedicinal plants used by Indian aborigines against 6 multidrug resistant Gram-positive pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Mahesh Chandra Sahu

    2015-02-01

    Full Text Available Objective: To monitor in vitro antibacterial activities of leaf extracts of 30 common and noncommon plants used by aborigines in Kalahandi district, Odisha, against 6 clinically isolated multidrug resistant (MDR Gram-positive bacteria of 3 genera, Staphylococcus, Streptococcus, and Enterococcus. Methods: The antibiotic sensitivity patterns of 6 bacterial strains were studied with the diskdiffusion method with 1 7 antibiotics belonging to 8 classes. Monitored plants have ethnomedicinal use and several are used as traditional medicines. Antibacterial properties were studied with the agar-well diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration values of ethanolic and aqueous extracts of plants were determined by the microbroth-dilution method. Results: Ethanolic plant-extracts had the better antibacterial potencies in comparison to their corresponding aqueous extracts. Plants with most conspicuous antibacterial properties in controlling MDR strains of Gram-positive bacteria were aqueous and ethanolic extracts of plants, Ixora coccinea, Nyctanthes arbor-tristis, Polycythaemia rubra, Pongamia pinnata and Syzygium cumini, Carthamus tinctorius, Cucurbita maxima, Murraya koenigii, Leucas aspera, Plumbago indica and Psidium guajava. Ethanolic extracts of most plants had phytochemicals, alkaloids, glycosides, terpenoids, reducing sugars, saponins, tannins, flavonoids and steroids. Conclusions: These plants could be used further for the isolation of pure compounds to be used as complementary non-microbial antimicrobial medicines.

  3. Sequence-Based Characterization of Tn5801-Like Genomic Islands in Tetracycline-Resistant Staphylococcus pseudintermedius and Other Gram-positive Bacteria from Humans and Animals

    DEFF Research Database (Denmark)

    de Vries, Lisbeth Elvira; Hasman, Henrik; Jurado Rabadán, Sonia

    2016-01-01

    Antibiotic resistance in pathogens is often associated with mobile genetic elements, such as genomic islands (GI) including integrative and conjugative elements (ICEs). These can transfer resistance genes within and between bacteria from humans and/or animals. The aim of this study was to investi......Antibiotic resistance in pathogens is often associated with mobile genetic elements, such as genomic islands (GI) including integrative and conjugative elements (ICEs). These can transfer resistance genes within and between bacteria from humans and/or animals. The aim of this study......-like GIs appear to be relatively common in tetracycline-resistant S. pseudintermedius in Denmark. Almost identical Tn5801-like GIs were identified in different Gram-positive species of pet and human origin, suggesting that horizontal transfer of these elements has occurred between S. pseudintermedius...

  4. Lactobacillus plantarum gene clusters encoding putative cell-surface protein complexes for carbohydrate utilization are conserved in specific gram-positive bacteria

    Directory of Open Access Journals (Sweden)

    Muscariello Lidia

    2006-05-01

    Full Text Available Abstract Background Genomes of gram-positive bacteria encode many putative cell-surface proteins, of which the majority has no known function. From the rapidly increasing number of available genome sequences it has become apparent that many cell-surface proteins are conserved, and frequently encoded in gene clusters or operons, suggesting common functions, and interactions of multiple components. Results A novel gene cluster encoding exclusively cell-surface proteins was identified, which is conserved in a subgroup of gram-positive bacteria. Each gene cluster generally has one copy of four new gene families called cscA, cscB, cscC and cscD. Clusters encoding these cell-surface proteins were found only in complete genomes of Lactobacillus plantarum, Lactobacillus sakei, Enterococcus faecalis, Listeria innocua, Listeria monocytogenes, Lactococcus lactis ssp lactis and Bacillus cereus and in incomplete genomes of L. lactis ssp cremoris, Lactobacillus casei, Enterococcus faecium, Pediococcus pentosaceus, Lactobacillius brevis, Oenococcus oeni, Leuconostoc mesenteroides, and Bacillus thuringiensis. These genes are neither present in the genomes of streptococci, staphylococci and clostridia, nor in the Lactobacillus acidophilus group, suggesting a niche-specific distribution, possibly relating to association with plants. All encoded proteins have a signal peptide for secretion by the Sec-dependent pathway, while some have cell-surface anchors, novel WxL domains, and putative domains for sugar binding and degradation. Transcriptome analysis in L. plantarum shows that the cscA-D genes are co-expressed, supporting their operon organization. Many gene clusters are significantly up-regulated in a glucose-grown, ccpA-mutant derivative of L. plantarum, suggesting catabolite control. This is supported by the presence of predicted CRE-sites upstream or inside the up-regulated cscA-D gene clusters. Conclusion We propose that the CscA, CscB, CscC and Csc

  5. The Effect of Bicarbonate on the Microbial Dissolution of Autunite Mineral in the Presence of Gram-Positive Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Medina, Paola; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel

    2015-06-01

    Bacteria are key players in the processes that govern fate and transport of contaminants. The uranium release from Na and Ca-autunite by Arthrobacter oxydans strain G968 was evaluated in the presence of bicarbonate ions. This bacterium was previously isolated from Hanford Site soil and in earlier prescreening tests demonstrated low tolerance to U(VI) toxicity compared to other A.oxydans isolates. Experiments were conducted using glass serum bottles as mixed bioreactors and sterile 6-well cell culture plates with inserts separating bacteria cells from mineral solids. Reactors containing phosphorus-limiting media were amended with bicarbonate ranging between 0-10 mM and metaautunite solids to provide a U(VI) concentration of 4.4 mmol/L. Results showed that in the presence of bicarbonate, A.oxydans G968 was able to enhance the release of U(VI) from Na and Ca autunite at the same capacity as other A.oxydans isolates with relatively high tolerance to U(VI). The effect of bacterial strains on autunite dissolution decreases as the concentration of bicarbonate increases. The results illustrate that direct interaction between the bacteria and the mineral is not necessary to result in U (VI) biorelease from autunite. The formation of secondary calcium-phosphate mineral phases on the surface of the mineral during the dissolution can ultimately reduce the natural autunite mineral contact area, which bacterial cells can access. This thereby reduces the concentration of uranium released into the solution. This study provides a better understanding of the interactions between meta-autunite and microbes in conditions mimicking arid and semiarid subsurface environments of western U.S.

  6. The Na+ transport in gram-positive bacteria defect in the Mrp antiporter complex measured with 23Na nuclear magnetic resonance.

    Science.gov (United States)

    Górecki, Kamil; Hägerhäll, Cecilia; Drakenberg, Torbjörn

    2014-01-15

    (23)Na nuclear magnetic resonance (NMR) has previously been used to monitor Na(+) translocation across membranes in gram-negative bacteria and in various other organelles and liposomes using a membrane-impermeable shift reagent to resolve the signals resulting from internal and external Na(+). In this work, the (23)Na NMR method was adapted for measurements of internal Na(+) concentration in the gram-positive bacterium Bacillus subtilis, with the aim of assessing the Na(+) translocation activity of the Mrp (multiple resistance and pH) antiporter complex, a member of the cation proton antiporter-3 (CPA-3) family. The sodium-sensitive growth phenotype observed in a B. subtilis strain with the gene encoding MrpA deleted could indeed be correlated to the inability of this strain to maintain a lower internal Na(+) concentration than an external one. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for gram-positive bacteria over erythrocytes.

    Science.gov (United States)

    Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

    2013-05-07

    Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (gram-positive Bacillus subtilis, gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects.

  8. Self-generated covalent cross-links in the cell-surface adhesins of Gram-positive bacteria.

    Science.gov (United States)

    Baker, Edward N; Squire, Christopher J; Young, Paul G

    2015-10-01

    The ability of bacteria to adhere to other cells or to surfaces depends on long, thin adhesive structures that are anchored to their cell walls. These structures include extended protein oligomers known as pili and single, multi-domain polypeptides, mostly based on multiple tandem Ig-like domains. Recent structural studies have revealed the widespread presence of covalent cross-links, not previously seen within proteins, which stabilize these domains. The cross-links discovered so far are either isopeptide bonds that link lysine side chains to the side chains of asparagine or aspartic acid residues or ester bonds between threonine and glutamine side chains. These bonds appear to be formed by spontaneous intramolecular reactions as the proteins fold and are strategically placed so as to impart considerable mechanical strength. © 2015 Authors; published by Portland Press Limited.

  9. Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

    Science.gov (United States)

    Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

  10. Multicenter evaluation of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Gram-positive aerobic bacteria.

    Science.gov (United States)

    Rychert, Jenna; Burnham, Carey-Ann D; Bythrow, Maureen; Garner, Omai B; Ginocchio, Christine C; Jennemann, Rebecca; Lewinski, Michael A; Manji, Ryhana; Mochon, A Brian; Procop, Gary W; Richter, Sandra S; Sercia, Linda; Westblade, Lars F; Ferraro, Mary Jane; Branda, John A

    2013-07-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting.

  11. A Trojan-Horse Strategy Including a Bacterial Suicide Action for the Efficient Use of a Specific Gram-Positive Antibiotic on Gram-Negative Bacteria.

    Science.gov (United States)

    Schalk, Isabelle J

    2018-05-10

    In the alarming context of rising bacterial antibiotic resistance, there is an urgent need to discover new antibiotics or increase and/or enlarge the activity of those currently in use. The need for new antibiotics is even more urgent in the case of Gram-negative bacteria, such as Acinetobacter, Pseudomonas, and Enterobacteria, which have become resistant to many antibiotics and have an outer membrane with very low permeability to drugs. Vectorization of antibiotics using siderophores may be a solution to bypass such a bacterial wall: the drugs use the iron transporters of the outer membrane as gates to enter bacteria in a Trojan-horse strategy. Designing siderophore-antibiotics that can cross outer membranes has become almost routine, but their transport across the inner membrane is still a limiting step, as well as a strategy that allows dissociation of the antibiotic from the siderophore once inside the bacteria. Liu et al. ( J. Med. Chem. 2018 , DOI: 10.1021/acs.jmedchem.8b00218 ) report the synthesis of a siderophore-cephalosporin compound and demonstrate that β-lactams, such as cephalosporins, can serve as β-lactamase-triggered releasable linkers to allow intracellular delivery of Gram-positive antibiotics to Gram-negative bacteria.

  12. LiF Reduces MICs of Antibiotics against Clinical Isolates of Gram-Positive and Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    H. C. Syed

    2012-01-01

    Full Text Available Antibiotic resistance is an ever-growing problem yet the development of new antibiotics has slowed to a trickle, giving rise to the use of combination therapy to eradicate infections. The purpose of this study was to evaluate the combined inhibitory effect of lithium fluoride (LiF and commonly used antimicrobials on the growth of the following bacteria: Enterococcus faecalis, Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, and Streptococcus pneumoniae. The in vitro activities of ceftazidime, sulfamethoxazole-trimethoprim, streptomycin, erythromycin, amoxicillin, and ciprofloxacin, doxycycline, alone or combined with LiF were performed by microdilution method. MICs were determined visually following 18–20 h of incubation at 37°C. We observed reduced MICs of antibiotics associated with LiF ranging from two-fold to sixteen-fold. The strongest decreases of MICs observed were for streptomycin and erythromycin associated with LiF against Acinetobacter baumannii and Streptococcus pneumoniae. An eight-fold reduction was recorded for streptomycin against S. pneumoniae whereas an eight-fold and a sixteen-fold reduction were obtained for erythromycin against A. baumannii and S. pneumoniae. This suggests that LiF exhibits a synergistic effect with a wide range of antibiotics and is indicative of its potential as an adjuvant in antibiotic therapy.

  13. An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria.

    Science.gov (United States)

    Cox, Georgina; Koteva, Kalinka; Wright, Gerard D

    2014-07-01

    An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. The anthracycline Antibiotic 301A(1) was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure-activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A(1) abolishes activity. Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

    Science.gov (United States)

    Cox, Georgina; Koteva, Kalinka; Wright, Gerard D.

    2014-01-01

    Objectives An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. Methods E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. Results The anthracycline Antibiotic 301A1 was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure–activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A1 abolishes activity. Conclusions Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. PMID:24627312

  15. The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study

    International Nuclear Information System (INIS)

    Abbaszadegan, A.; Ghahramani, Y.; Nabavizadeh, M.; Gholami, A.; Hemmateenejad, I.; Dorostkar, S.; Sharghi, H.

    2014-01-01

    The bactericidal efficiency of various positively and negatively charged silver nanoparticles has been extensively evaluated in literature, but there is no report on efficacy of neutrally charged silver nanoparticles. The goal of this study is to evaluate the role of electrical charge at the surface of silver nanoparticles on antibacterial activity against a panel of microorganisms. Three different silver nanoparticles were synthesized by different methods, providing three different electrical surface charges (positive, neutral, and negative). The antibacterial activity of these nanoparticles was tested against gram-positive (i.e., Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes) and gram-negative (i.e., Escherichia coli and Proteus vulgaris) bacteria. Well diffusion and micro-dilution tests were used to evaluate the bactericidal activity of the nanoparticles. According to the obtained results, the positively-charged silver nanoparticles showed the highest bactericidal activity against all microorganisms tested. The negatively charged silver nanoparticles had the least and the neutral nanoparticles had intermediate antibacterial activity. The most resistant bacteria were Proteus vulgaris. We found that the surface charge of the silver nanoparticles was a significant factor affecting bactericidal activity on these surfaces. Although the positively charged nanoparticles showed the highest level of effectiveness against the organisms tested, the neutrally charged particles were also potent against most bacterial species.

  16. Gram-Positive Bacteria with Probiotic Potential for the Apis mellifera L. Honey Bee: The Experience in the Northwest of Argentina.

    Science.gov (United States)

    Audisio, Marcela Carina

    2017-03-01

    Apis mellifera L. is one of the most important natural pollinators of significant crops and flowers around the world. It can be affected by different types of illnesses: american foulbrood, nosemosis, varroasis, viruses, among others. Such infections mainly cause a reduction in honey production and in extreme situations, the death of the colony. Argentina is the world's second largest honey exporter and the third largest honey producer, after China and Turkey. Given both the prominence of the honey bee in nature and the economic importance of apiculture in Argentina and the world, it is crucial to develop efficient and sustainable strategies to control honey bee diseases and to improve bee colony health. Gram-positive bacteria, such as lactic acid bacteria, mainly Lactobacillus, and Bacillus spp. are promising options. In the Northwest of Argentina, several Lactobacillus and Bacillus strains from the honey bee gut and honey were isolated by our research group and characterized by using in vitro tests. Two strains were selected because of their potential probiotic properties: Lactobacillus johnsonii CRL1647 and Bacillus subtilis subsp. subtilis Mori2. Under independent trials with both experimental and commercial hives, it was determined that each strain was able to elicit probiotic effects on bee colonies reared in the northwestern region of Argentina. One result was the increase in egg-laying by the queen which therefore produced an increase in bee number and, consequently, a higher honey yield. Moreover, the beneficial bacteria reduced the incidence of two important bee diseases: nosemosis and varroosis. These results are promising and extend the horizon of probiotic bacteria to the insect world, serving beekeepers worldwide as a natural tool that they can administer as is, or combine with other disease-controlling methods.

  17. Synergistic effect of Carum copticum and Mentha piperita essential oils with ciprofloxacin, vancomycin, and gentamicin on Gram-negative and Gram-positive bacteria

    Science.gov (United States)

    Talei, Gholam-Reza; Mohammadi, Mohsen; Bahmani, Mahmoud; Kopaei, Mahmoud Rafieian

    2017-01-01

    Background: Infectious diseases have always been an important health issue in human communities. In the recent years, much research has been conducted on antimicrobial effects of nature-based compounds because of increased prevalence of antibiotic resistance. The present study was conducted to investigate synergistic effect of Carum copticum and Mentha piperita essential oils with ciprofloxacin, vancomycin, and gentamicin on Gram-negative and Gram-positive bacteria. Materials and Methods: In this experimental study, the synergistic effects of C. copticum and M. piperita essential oils with antibiotics on Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027), Staphylococcus epidermidis (ATCC 14990), and Listeria monocytogenes (ATCC 7644) were studied according to broth microdilution and the MIC and fractional inhibitory concentration (FIC) of these two essential oils determined. Results: C. copticum essential oil at 30 μg/ml could inhibit S. aureus, and in combination with vancomycin, decreased MIC from 0.5 to 0.12 μg/ml. Moreover, the FIC was derived 0.24 μg/ml which represents a potent synergistic effect with vancomycin against S. aureus growth. C. copticum essential oil alone or combined with other antibiotics is effective in treating bacterial infections. Conclusions: In addition, C. copticum essential oil can strengthen the activities of certain antibiotics, which makes it possible to use this essential oil, especially in drug resistance or to lower dosage or toxicity of the drugs. PMID:28929050

  18. 3,5-Dioxopyrazolidines, Novel Inhibitors of UDP-N- Acetylenolpyruvylglucosamine Reductase (MurB) with Activity against Gram-Positive Bacteria

    Science.gov (United States)

    Yang, Youjun; Severin, Anatoly; Chopra, Rajiv; Krishnamurthy, Girija; Singh, Guy; Hu, William; Keeney, David; Svenson, Kristine; Petersen, Peter J.; Labthavikul, Pornpen; Shlaes, David M.; Rasmussen, Beth A.; Failli, Amedeo A.; Shumsky, Jay S.; Kutterer, Kristina M. K.; Gilbert, Adam; Mansour, Tarek S.

    2006-01-01

    A series of 3,5-dioxopyrazolidines was identified as novel inhibitors of UDP-N-acetylenolpyruvylglucosamine reductase (MurB). Compounds 1 to 3, which are 1,2-bis(4-chlorophenyl)-3,5-dioxopyrazolidine-4-carboxamides, inhibited Escherichia coli MurB, Staphyloccocus aureus MurB, and E. coli MurA with 50% inhibitory concentrations (IC50s) in the range of 4.1 to 6.8 μM, 4.3 to 10.3 μM, and 6.8 to 29.4 μM, respectively. Compound 4, a C-4-unsubstituted 1,2-bis(3,4-dichlorophenyl)-3,5-dioxopyrazolidine, showed moderate inhibitory activity against E. coli MurB, S. aureus MurB, and E. coli MurC (IC50s, 24.5 to 35 μM). A fluorescence-binding assay indicated tight binding of compound 3 with E. coli MurB, giving a dissociation constant of 260 nM. Structural characterization of E. coli MurB was undertaken, and the crystal structure of a complex with compound 4 was obtained at 2.4 Å resolution. The crystal structure indicated the binding of a compound at the active site of MurB and specific interactions with active-site residues and the bound flavin adenine dinucleotide cofactor. Peptidoglycan biosynthesis studies using a strain of Staphylococcus epidermidis revealed reduced peptidoglycan biosynthesis upon incubation with 3,5-dioxopyrazolidines, with IC50s of 0.39 to 11.1 μM. Antibacterial activity was observed for compounds 1 to 3 (MICs, 0.25 to 16 μg/ml) and 4 (MICs, 4 to 8 μg/ml) against gram-positive bacteria including methicillin-resistant S. aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae. PMID:16436710

  19. Burdock (Arctium lappa Leaf Extracts Increase the In Vitro Antimicrobial Efficacy of Common Antibiotics on Gram-positive and Gram-negative Bacteria

    Directory of Open Access Journals (Sweden)

    Pirvu Lucia

    2017-04-01

    Full Text Available This work aimed to study the potential effects of four Arctii folium extracts, 5 mg gallic [GAE] acid equivalents per 1 mL sample, on six antibiotics (Ampicillin/AM, Tetracycline/TE, Ciprofloxacin/CIP, Sulfamethoxazole-Trimethoprim/SXT, Chloramphenicol/C and Gentamicin/CN tested on four Gram-positive (Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, and Staphylococcus epidermidis ATCC 12228 and five Gram-negative (Proteus mirabilis ATCC 29245, Escherichia coli ATCC 35218, E. coli ATCC 11229, E. coli ATCC 8739, and Bacillus cereus ATCC 11778 bacteria. Arctii folium extracts were the whole ethanol extract/W and subsequent ethyl acetate/EA, aqueous/AQ, and chloroform/CHL fractions. Chemical qualitative analysis (HPTLC method emphasized five main polyphenol compounds in Arctii folium polar extracts: chlorogenic acid (Rf≈0.52/0.55 and its isomer, 1,5-di-O-caffeoylquinic acid (Rf≈0.90/0.92, plus cynarin (Rf≈0.77, hyperoside (Rf≈0.68/0.64 and isoquercitrin (Rf≈0.69/0.71. Microbiological screening indicated Arctii folium polar extracts (AQ and W efficacy on S. epidermidis ATCC 12228; the MIC values were in the range of common antibiotics, being 32 and 128 μg GAE per mL sample respectively. The unpredictable effects (stimulatory or inhibitory of Arctii folium extracts in combination with typical antibiotics as well as a potential use of the whole ethanol extract/W for restoring the antimicrobial potency of susceptible antibiotics have also been evidenced.

  20. Investigating of the antimicrobial effect of total extract of Tribulus terrestris against some gram positive and negative bacteria and candida spp.

    Directory of Open Access Journals (Sweden)

    Mojdeh Hakemi Vala

    2014-08-01

    Full Text Available Introduction: In the recent years, due to the wide spread of resistant bacteria on one side and several different reports about the side effects of chemical drugs on the other side, vast researches on the medicinal plants have been started. In this study, antimicrobial effect of total extract of Tribulus terrestris L. and its fraction containing Benzoxazine derivative (Terresoxazine was studied for the first time in Iran.Materials and methods: Total aqueous extract of aerial parts of the plant was prepared and in order to separate the components of aqueous extract, liquid/liquid extraction with Petroleum ether was used. Formation of three layers was the result of this extraction. Layers included water fraction, Petroleum ether fraction and a third layer which was formed at the interface of water and petroleum ether. LC/MS system proved the existence of Benzixazine derivative in the water fraction and the thirds fraction. Antimicrobial effects of total extract, water fraction and the third fraction (which were the layers formed after the extraction process were examined against 10 Gram positive and negative and candida spp by cup plate method and Disk diffusion method. Also, the MIC and MBC were determined by micro dilution method.Results: Of 8 evaluated bacteria and 2 Candida spp, the total extract showed antibacterial effect only against E.coli, P.aeruginosa and B.subtilis. Size of the zone of inhibitation increased with increasing the concentration of the extract. Fraction containing Benzoxazine derivative had no effect against tested microbes. MIC and MBC determination showed that B.subtilis had the least sensitivity to the total extract, comparing to other microorganisms. Besides, comparing the zone of inhibitation of Penicillin 200 mg/ml and the zone of inhibitation of the total aqueous extract shows that the solution of total extract in water with 1000 mg/ml concentration and the solution of total extract in DMSO10% with 750 mg/ml density

  1. Evaluation of Inhibitory and Lethal Effects of Aqueous, Ethanolic and Hydroalcoholic Extracts of Aerial Parts of Salvia chorassanica against Some Gram-negative and Gram-positive Bacteria in Vitro

    Directory of Open Access Journals (Sweden)

    Azam Mehraban

    2016-05-01

    Full Text Available Abstract Background and Objectives: Development of bacterial resistance to antibiotics has led to an increased tendency to development of new more effective and non-toxic antimicrobial compounds. In this study, the inhibitory and lethal effects of aqueous, ethanolic, and hydroalcoholic extracts of aerial parts of Salvia chorassanica were evaluated against Listeria monocytogenes, Bacillus cereus, Salmonella typhi, and Escherichia coli O:157. Methods: In this study, Kirby–Bauer disk diffusion method was used to evaluate antimicrobial activity. In this method, bacteria were cultivated as grass culture in Mueller Hinton Agar (MHA media. To determine the minimum inhibitory concentration and minimum bactericidal concentration, micro-dilution method with ELISA and addition of phenyl tetrazolium chloride reagent, were used. Data were analyzed using one-way ANOVA and Duncan’s test at the significance level of p<0.05. Results: The highest diameter of inhibition in agar diffusion method was related to hydroalcoholic extract of aerial parts of Salvia chorassanica against Gram-positive bacteria Bacillus cereus. The amount of calculated MIC of hydro-alcoholic extract for Gram-positive bacteria was 30mg/ml. This amount was the lowest among other measured MIC. Conclusion: Based on the results of this study, Gram-negative bacteria showed more resistance to different extracts of aerial parts of Salvia chorassanica as compared to Gram-positive bacteria, so that Salmonella typhi was found to be the most resistant bacterium among the tested bacteria.

  2. Chemical analysis of isolated cell walls of Gram-positive bacteria and the determination of the cell wall to cell mass ratio.

    NARCIS (Netherlands)

    Wal, van der A.; Norde, W.; Bendinger, B.; Zehnder, A.J.B.; Lyklema, J.

    1997-01-01

    Cell walls of five Gram-positive bacterial strains, including four coryneforms and a Bacillus brevis strain were isolated and subsequently chemically analysed. The wall contribution to the total cell mass is calculated from a comparison of D-Lactate concentrations in hydrolysates of whole cells and

  3. Use of the Lactococcal nisA Promoter To Regulate Gene Expression in Gram-Positive Bacteria : Comparison of Induction Level and Promoter Strength

    NARCIS (Netherlands)

    Eichenbaum, Zehava; Federle, Michael J.; Marra, Diana; Vos, Willem M. de; Kuipers, Oscar P.; Kleerebezem, Michiel; Scott, June R.

    1998-01-01

    We characterized the regulated activity of the lactococcal nisA promoter in strains of the gram-positive species Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis, and Bacillus subtilis. nisA promoter activity was dependent on the proteins NisR and

  4. Rapid and reliable identification of Gram-negative bacteria and Gram-positive cocci by deposition of bacteria harvested from blood cultures onto the MALDI-TOF plate.

    OpenAIRE

    Barnini, S; Ghelardi, Emilia; Brucculeri, V; Morici, Paola; Lupetti, Antonella

    2015-01-01

    Background Rapid identification of the causative agent(s) of bloodstream infections using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) methodology can lead to increased empirical antimicrobial therapy appropriateness. Herein, we aimed at establishing an easier and simpler method, further referred to as the direct method, using bacteria harvested by serum separator tubes from positive blood cultures and placed onto the polished steel target plate for rapid identif...

  5. Competitive binding of polyethyleneimine-coated gold nanoparticles to enzymes and bacteria: a key mechanism for low-level colorimetric detection of gram-positive and gram-negative bacteria

    International Nuclear Information System (INIS)

    Thiramanas, Raweewan; Laocharoensuk, Rawiwan

    2016-01-01

    The article describes a simple and rapid method for colorimetric detection of bacteria. It is based on competitive binding of positively charged polyethyleneimine-coated gold nanoparticles (PEI-AuNPs) to negatively charged enzymes and bacteria. The PEI-AuNPs are electrostatically attracted by both the bacterial surface and the enzyme β-galactosidase (β-Gal). Binding to the latter results in the inhibition of enzyme activity. However, in the presence of a large number of bacteria, the PEI-AuNPs preferentially bind to bacteria. Hence, the enzyme will not be inhibited and its activity can be colorimetrically determined via hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside (CPRG). The detection limit of this assay is as low as 10 cfu·mL −1 , and the linear range extends from 10 6 to 10 8 cfu·mL −1 . The assay is applicable to both Gram-negative (such as enterotoxigenic Escherichia coli; ETEC) and Gram-positive (Staphylococcus aureus; S. aureus) bacteria. Results are obtained within 10 min using an optical reader, and within 2–3 h by bare-eye detection. The method was applied to the identification of ETEC contamination at a level of 10 cfu·mL −1 in spiked drinking water. Given its low detection limit and rapidity (sample preconcentration is not required), this method holds great promise for on-site detection of total bacterial contamination. (author)

  6. Lactococcus lactis TrxD represents a subgroup of thioredoxins prevalent in Gram-positive bacteria containing WCXDC active site motifs

    DEFF Research Database (Denmark)

    Björnberg, Olof; Efler, Petr; Epie, Denis Ebong

    2014-01-01

    Three protein disulfide reductases of the thioredoxin superfamily from the industrially important Gram-positive Lactococcus lactis (LlTrxA, LlTrxD and LlNrdH) are compared to the "classical" thioredoxin from Escherichia coil (EcTrx1). LlTrxA resembles EcTrx1 with a WCGPC active site motif and other...... capacity to reduce insulin disulfides and their exposed active site thiol is alkylated at a similar rate at pH 7.0. LlTrxD on the other hand, is alkylated by iodoacetamide at almost 100 fold higher rate and shows no activity towards insulin disulfides. LlTrxA, LlTrxD and L1NrdH are all efficiently reduced...

  7. Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

    International Nuclear Information System (INIS)

    Peszke, Jerzy; Nowak, Anna; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena; Krzyściak, Paweł; Zygoń, Patrycja; Ratuszna, Alicja; Ostafin, Marek M.

    2016-01-01

    Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu 2 O/CuO nanoparticles.

  8. Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Peszke, Jerzy; Nowak, Anna, E-mail: ana.maria.nowak@gmail.com; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena [University of Silesia, A. Chelkowski Institute of Physics (Poland); Krzyściak, Paweł [Jagiellonian University Medical College, Department of Mycology Chair of Microbiology (Poland); Zygoń, Patrycja [Czestochowa University of Technology, Institute of Materials Engineering (Poland); Ratuszna, Alicja [University of Silesia, A. Chelkowski Institute of Physics (Poland); Ostafin, Marek M. [Department of Microbiology University of Agriculture (Poland)

    2016-12-15

    Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu{sub 2}O/CuO nanoparticles.

  9. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance.

    Directory of Open Access Journals (Sweden)

    Demetrio L Valle

    Full Text Available Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC and the minimum bactericidal concentrations (MBC of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA, vancomycin-resistant Enterococcus (VRE, extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn. Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant

  10. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance.

    Science.gov (United States)

    Valle, Demetrio L; Cabrera, Esperanza C; Puzon, Juliana Janet M; Rivera, Windell L

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria.

  11. Adhesion and inactivation of Gram-negative and Gram-positive bacteria on photoreactive TiO2/polymer and Ag-TiO2/polymer nanohybrid films

    Science.gov (United States)

    Tallósy, Szabolcs Péter; Janovák, László; Nagy, Elisabeth; Deák, Ágota; Juhász, Ádám; Csapó, Edit; Buzás, Norbert; Dékány, Imre

    2016-05-01

    The aim of this study was to develop photoreactive surface coatings, possessing antibacterial properties and can be activated under visible light illumination (λmax = 405 nm) using LED-light source. The photocatalytically active titanium dioxide (TiO2) was functionalized with silver nanoparticles (Ag NPs) and immobilized in polyacrylate based nanohybrid thin film in order to facilitate visible light activity (λAg/TiO2,max = 500 nm). First, the photocatalytic activity was modelled by following ethanol vapor degradation. The plasmonic functionalization resulted in 15% enhancement of the activity compared to pure TiO2. The photoreactive antimicrobial (5 log reduction of cfu in 2 h) surface coatings are able to inactivate clinically relevant pathogen strains (methicillin resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) within short time (60-120 min) due to the formed and quantified reactive oxygen species (ROS). The existence of electrostatic interactions between the negatively charged bacteria (from -0.89 to -3.19 μeq/109 cfu) and positively charged photocatalyst particles (in the range of +0.38 and +12.3 meq/100 g) was also proven by charge titration measurements. The surface inactivation of the bacteria and the photocatalytic degradation of the cell wall component were also confirmed by fluorescence and transmission electron microscopic observations, respectively. According to the results an effective sterilizing system and prevention strategy can be developed and carried out against dangerous microorganisms in health care.

  12. CRP-ductin, the mouse homologue of gp-340/deleted in malignant brain tumors 1 (DMBT1), binds gram-positive and gram-negative bacteria and interacts with lung surfactant protein D

    DEFF Research Database (Denmark)

    Madsen, Jens; Tornøe, Ida; Nielsen, Ole

    2003-01-01

    CRP-ductin is a protein expressed mainly by mucosal epithelial cells in the mouse. Sequence homologies indicate that CRP-ductin is the mouse homologue of human gp-340, a glycoprotein that agglutinates microorganisms and binds the lung mucosal collectin surfactant protein-D (SP-D). Here we report...... that purified CRP-ductin binds human SP-D in a calcium-dependent manner and that the binding is not inhibited by maltose. The same properties have previously been observed for gp-340 binding of SP-D. CRP-ductin also showed calcium-dependent binding to both gram-positive and -negative bacteria. A polyclonal...... antibody raised against gp-340 reacted specifically with CRP-ductin in Western blots. Immunoreactivity to CRP-ductin was found in the exocrine pancreas, in epithelial cells throughout the gastrointestinal tract and in the parotid ducts. A panel of RNA preparations from mouse tissues was screened for CRP...

  13. Chemical constituents of Helichrysum italicum (Roth G. Don essential oil and their antimicrobial activity against Gram-positive and Gram-negative bacteria, filamentous fungi and Candida albicans

    Directory of Open Access Journals (Sweden)

    Bouzid Djihane

    2017-07-01

    Full Text Available The aerial parts of Helichrysum italicum (Roth G. Don were subjected to hydrodistillation to obtain essential oils which had been analyzed by gas chromatography and gas chromatography coupled with mass spectrometry and tested for antimicrobial activity against 12 bacteria, two yeasts and four fungi by agar diffusion method. The essential oil yielded 0.44% (v/w and 67 compounds accounting for 99.24% of the oil were identified with a high content of oxygenated sesquiterpenes (61.42%. The most oxygenated sesquiterpene compounds were α-Cedrene (13.61%, α-Curcumene (11.41%, Geranyl acetate (10.05%, Limonene (6.07%, Nerol (5.04%, Neryl acetate (4.91% and α-Pinene (3.78%. The antimicrobial activity of the essential oil was assayed by using the disk diffusion method on Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Micrococcus luteus ATCC 4698, Klebsiella pneumonia ATCC 4352, Enterococcus cereus ATCC 2035, Bacillus cereus ATCC 10876, Staphylococcus epidermidis ATCC 12228, Bacillus subtilis ATCC 9372, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 49452, Proteus mirabilis ATCC 35659, Listeria monocytogenes ATCC 15313 and yeasts Candida albicans ATCC 10231, Saccharomyces cerevisiae ATCC 9763 and fungi, Fusarium solani var. coeruleum, Aspergillus niger, Alternaria alternata, Ascochyta rabiei. H. italicum inhibited the growth of all the tested microorganisms except three bacteria, E. coli ATCC 25922, K. pneumonia ATCC 4352 and L. monocytogenes ATCC 15313. The most sensitive bacterium was E. cereus ATCC 2035 with minimum inhibitory and bactericidal concentrations of 0.79 μg ml−1. A minimum fungistatic and fungicide concentration of 6.325 μg ml−1 and 12.65 μg ml−1 respectively was obtained with C. albicans ATCC 10231 and S. cerevisiae ATCC 9763. However the four fungi were more resistant with fungistatic minimum concentration ranging from 6.325 μg ml−1 to 50.6 μg ml−1 and a fungicide minimum

  14. Chemical constituents of Helichrysum italicum (Roth) G. Don essential oil and their antimicrobial activity against Gram-positive and Gram-negative bacteria, filamentous fungi and Candida albicans.

    Science.gov (United States)

    Djihane, Bouzid; Wafa, Nouioua; Elkhamssa, Soltani; Pedro, De Haro Juan; Maria, Angeles Esteban; Mohamed Mihoub, Zerroug

    2017-07-01

    The aerial parts of Helichrysum italicum (Roth) G. Don were subjected to hydrodistillation to obtain essential oils which had been analyzed by gas chromatography and gas chromatography coupled with mass spectrometry and tested for antimicrobial activity against 12 bacteria, two yeasts and four fungi by agar diffusion method. The essential oil yielded 0.44% (v/w) and 67 compounds accounting for 99.24% of the oil were identified with a high content of oxygenated sesquiterpenes (61.42%). The most oxygenated sesquiterpene compounds were α-Cedrene (13.61%), α-Curcumene (11.41%), Geranyl acetate (10.05%), Limonene (6.07%), Nerol (5.04%), Neryl acetate (4.91%) and α-Pinene (3.78%). The antimicrobial activity of the essential oil was assayed by using the disk diffusion method on Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Micrococcus luteus ATCC 4698, Klebsiella pneumonia ATCC 4352, Enterococcus cereus ATCC 2035, Bacillus cereus ATCC 10876, Staphylococcus epidermidis ATCC 12228, Bacillus subtilis ATCC 9372, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 49452, Proteus mirabilis ATCC 35659, Listeria monocytogenes ATCC 15313 and yeasts Candida albicans ATCC 10231, Saccharomyces cerevisiae ATCC 9763 and fungi, Fusarium solani var. coeruleum , Aspergillus niger , Alternaria alternata , Ascochyta rabiei . H. italicum inhibited the growth of all the tested microorganisms except three bacteria, E. coli ATCC 25922, K. pneumonia ATCC 4352 and L. monocytogenes ATCC 15313. The most sensitive bacterium was E. cereus ATCC 2035 with minimum inhibitory and bactericidal concentrations of 0.79 μg ml -1 . A minimum fungistatic and fungicide concentration of 6.325 μg ml -1 and 12.65 μg ml -1 respectively was obtained with C. albicans ATCC 10231 and S. cerevisiae ATCC 9763. However the four fungi were more resistant with fungistatic minimum concentration ranging from 6.325 μg ml -1 to 50.6 μg ml -1 and a fungicide minimum concentration of 50

  15. Comparison of TiO2 and ZnO nanoparticles for photocatalytic degradation of methylene blue and the correlated inactivation of gram-positive and gram-negative bacteria

    International Nuclear Information System (INIS)

    Barnes, Robert J.; Molina, Rodrigo; Xu Jianbin; Dobson, Peter J.; Thompson, Ian P.

    2013-01-01

    Titanium dioxide (TiO 2 ) and zinc oxide (ZnO) nanoparticles are important photocatalysts and as such have been extensively studied for the removal of organic compounds from contaminated air and water and for microbial disinfection. Despite much research on the effect of TiO 2 and ZnO nanoparticles on different bacterial species, uncertainties remain about which bacteria are more sensitive to these compounds. Very few studies have directly compared the toxicity of ZnO to TiO 2 under both light and dark conditions. In addition, authors investigating the photocatalytic inactivation of TiO 2 and ZnO nanoparticles on bacteria have failed to investigate the reactive oxygen species (ROS) generation of the nanoparticles, making it difficult to correlate killing action with the generation of ROS. In this study, three types of metal nanoparticle (ZnO 2 ) have been characterised and ROS production assessed through the degradation of methylene blue (MB). The photocatalytic killing potential of three nanoparticle concentrations (0.01, 0.1 and 1 g/L) was then assessed on four representative bacteria: two gram-positive (S. aureus and B. subtilis) and two gram-negative (E. coli and P. aeruginosa). Results showed that out of the three nanoparticles tested, the TiO 2 nanoparticles generated more ROS than the ZnO nanoparticles, corresponding to a greater photocatalytic inactivation of three of the four species of bacteria examined. The MB decomposition results correlated well with the bacterial inactivation results with higher TiO 2 nanoparticle concentrations leading to greater ROS production and increased loss of cell viability. Although producing less ROS than the TiO 2 nanoparticles under ultraviolet light, the ZnO nanoparticles were toxic to two of the bacterial species even under dark conditions. In this study, no correlation between cell wall type and bacterial inactivation was observed for any of the nanoparticles tested although both gram-positive bacteria were sensitive to

  16. Enhanced antiadhesive properties of chitosan/hyaluronic acid polyelectrolyte multilayers driven by thermal annealing: Low adherence for mammalian cells and selective decrease in adhesion for Gram-positive bacteria.

    Science.gov (United States)

    Muzzio, Nicolás E; Pasquale, Miguel A; Diamanti, Eleftheria; Gregurec, Danijela; Moro, Marta Martinez; Azzaroni, Omar; Moya, Sergio E

    2017-11-01

    The development of antifouling coatings with restricted cell and bacteria adherence is fundamental for many biomedical applications. A strategy for the fabrication of antifouling coatings based on the layer-by-layer assembly and thermal annealing is presented. Polyelectrolyte multilayers (PEMs) assembled from chitosan and hyaluronic acid were thermally annealed in an oven at 37°C for 72h. The effect of annealing on the PEM properties and topography was studied by atomic force microscopy, ζ-potential, circular dichroism and contact angle measurements. Cell adherence on PEMs before and after annealing was evaluated by measuring the cell spreading area and aspect ratio for the A549 epithelial, BHK kidney fibroblast, C2C12 myoblast and MC-3T3-E1 osteoblast cell lines. Chitosan/hyaluronic acid PEMs show a low cell adherence that decreases with the thermal annealing, as observed from the reduction in the average cell spreading area and more rounded cell morphology. The adhesion of S. aureus (Gram-positive) and E. coli (Gram-negative) bacteria strains was quantified by optical microscopy, counting the number of colony-forming units and measuring the light scattering of bacteria suspension after detachment from the PEM surface. A 20% decrease in bacteria adhesion was selectively observed in the S. aureus strain after annealing. The changes in mammalian cell and bacteria adhesion correlate with the changes in topography of the chitosan/hyaluronic PEMs from a rough fibrillar 3D structure to a smoother and planar surface after thermal annealing. Copyright © 2017. Published by Elsevier B.V.

  17. Disruption and analysis of the clpB, clpC, and clpE genes in Lactococcus lactis: ClpE, a new Clp family in gram-positive bacteria

    DEFF Research Database (Denmark)

    Ingmer, Hanne; Vogensen, Finn K.; Hammer, Karin

    1999-01-01

    In the genome of the gram-positive bacterium Lactococcus lactis MG1363, we have identified three genes (clpC, clpE, and clpB) which encode Clp proteins containing two conserved ATP binding domains. The proteins encoded by two of the genes belong to the previously described ClpB and ClpC families....... The clpE gene, however, encodes a member of a new Clp protein family that is characterized by a short N-terminal domain including a putative zinc binding domain (-CX2CX22CX2C-). Expression of the 83-kDa ClpE protein as well as of the two proteins encoded by clpB was strongly induced by heat shock and...... was shown to participate in the degradation of randomly folded proteins in L. lactis, could be necessary for degrading proteins generated by certain types of stress....

  18. Non-covalent association of protein and capsular polysaccharide on bacteria-sized latex beads as a model for polysaccharide-specific humoral immunity to intact Gram-positive extracellular bacteria1

    Science.gov (United States)

    Colino, Jesus; Duke, Leah; Snapper, Clifford M.

    2013-01-01

    Intact Streptococcus pneumoniae, expressing type 14 capsular polysaccharide (PPS14) and type III Streptococcus agalactiae containing a PPS14 core capsule identical to PPS14, exhibit non-covalent associations of PPS14 and bacterial protein, in contrast to soluble covalent conjugates of these respective antigens. Both bacteria and conjugates induce murine PPS14-specific IgG responses dependent on CD4+ T cells. Further, secondary immunization with conjugate and S. agalactiae, although not S. pneumoniae, results in a boosted response. However, in contrast to conjugate, PPS14-specific IgG responses to bacteria lack affinity maturation, utilize the 44.1-idiotype and are dependent on marginal zone B cells. To better understand the mechanism underlying this dichotomy we developed a minimal model of intact bacteria in which PPS14 and pneumococcal surface protein A (PspA) were stably attached to 1 μm (bacteria-sized) latex beads, but not directly linked to each other, in contrast to PPS14-PspA conjugate. PPS14+[PspA] beads, similar to conjugate, induced in mice boosted PPS14-specific IgG secondary responses, dependent on T cells and ICOS-dependent costimulation, and in which priming could be achieved with PspA alone. In contrast to conjugate, but similar to intact bacteria, the primary PPS14-specific IgG response to PPS14+[PspA] beads peaked rapidly, with the secondary response highly enriched for the 44.1-idiotype and lacking affinity maturation. These results demonstrate that non-covalent association in a particle, of polysaccharide and protein, recapitulates essential immunologic characteristics of intact bacteria that are distinct from soluble covalent conjugates of these respective antigens. PMID:23926322

  19. Diesel degradation and biosurfactant production by Gram-positive ...

    African Journals Online (AJOL)

    The ability of Gram-positive bacteria to degrade diesel increased in a comparable trend as its biosurfactant production increased. The E24 index was highest at 87.6% for isolate D9. Isolates D2, D9 and D10, were identified as Paenibacillus sp. whilst isolate DJLB was found to belong to Stenotrophomonas sp. This study ...

  20. Surveillance of multidrug resistance of two Gram-positive pathogenic bacteria in a teaching hospital and in vitro efficacy of 30 ethnomedicinal plants used by an aborigine of India

    Directory of Open Access Journals (Sweden)

    Debasmita Dubey

    2012-08-01

    Full Text Available Objective: To record hospital- and community-acquired accounts of multidrug resistance (MDR of two Gram-positive pathogens, Staphylococcus aureus (S. aureus and Enterococcus faecalis (E. faecalis, by surveillance, and to evaluate antibacterial potencies of 30 plants with information on ethnomedicinal uses for infectious ailments by the aborigine Kandha tribe of Kalahandi district, Odisha (India, against both pathogens. Methods: Over a period of 6 months bacteria/ strains of S. aureus and E. faecalis were isolated from clinical samples in a teaching hospital and their antibiograms were ascertained using 17 antibiotics of 9 different groups. S. aureus strains were further tested for confirmation if they were methicillin and vancomycin resistant, similarly, E. faecalis strains for vancomycin resistance. Concentrated aqueous and ethanolic extracts of leaves/ barks of 30 plants were used for monitoring their antimicrobial potencies, by the agar-well diffusion method, along with qualitative phytochemical analyses. Results: From the surveillance, both pathogens were found MDR and it was evident that the distribution of MDR strains was more in hospital-acquired than community-acquired samples. Both aqueous and ethanolic extracts of plants, Diospyrous melanoxylon, Woodfordia fruticosa (W. fruticosa, Oroxylum indicum (O. indicum, Dalbergia paniculata and Lantana camara had the most significant in vitro controlling capacity against MDR strains of both bacteria. Further, extracts of Holarrhena antidysenterica, Aspidopterys tomentosa and Argyreia speciosa had moderate antibacterial activities. Ethanolic extracts of L. camara, O. indicum and W. fruticosa contained all the phytochemicals, alkaloids, glycosides, terpenoids, reducing sugars, saponins, tannins, flavonoids and steroids, which could be attributed to the recorded significant antibacterial activity. Conclusions: S. aureus strains have been found as the most widely prevailing pathogens in nosocomial

  1. Rolling-circle plasmids from Bacillus subtilis : complete nucleotide sequences and analyses of genes of pTA1015, pTA1040, pTA1050 and pTA1060, and comparisons with related plasmids from Gram-positive bacteria

    NARCIS (Netherlands)

    Meijer, W.J.; Schuurs-Wisman, Bea; Terpstra, P; Thorsted, P.; Thomas, C.M.; Holsappel, S; Venema, G; Bron, S

    Most small plasmids of Gram-positive bacteria use the rolling-circle mechanism of replication and several of these have been studied in considerable detail at the DNA level and for the function of their genes. Although most of the common laboratory Bacillus subtilis 168 strains do not contain

  2. Antiadhesion agents against Gram-positive pathogens.

    Science.gov (United States)

    Cascioferro, Stella; Cusimano, Maria Grazia; Schillaci, Domenico

    2014-01-01

    A fundamental step of Gram-positive pathogenesis is the bacterial adhesion to the host tissue involving interaction between bacterial surface molecules and host ligands. This review is focused on antivirulence compounds that target Gram-positive adhesins and on their potential development as therapeutic agents alternative or complementary to conventional antibiotics in the contrast of pathogens. In particular, compounds that target the sortase A, wall theicoic acid inhibitors, carbohydrates able to bind bacterial proteins and proteins capable of influencing the bacterial adhesion, were described. We further discuss the advantages and disadvantages of this strategy in the development of novel antimicrobials and the future perspective of this research field still at its first steps.

  3. Adhesion and inactivation of Gram-negative and Gram-positive bacteria on photoreactive TiO{sub 2}/polymer and Ag–TiO{sub 2}/polymer nanohybrid films

    Energy Technology Data Exchange (ETDEWEB)

    Tallósy, Szabolcs Péter [Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Semmelweis u. 6 (Hungary); Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged, Aradi v.t.1 (Hungary); Janovák, László [Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged, Aradi v.t.1 (Hungary); Nagy, Elisabeth [Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Semmelweis u. 6 (Hungary); Deák, Ágota [Department of Physical Chemistry and Materials Sciences, University of Szeged, H-6720 Szeged, Aradi v.t.1 (Hungary); Juhász, Ádám; Csapó, Edit [MTA-SZTE Supramolecular and Nanostructured Materials Research Group, Department of Medical Chemistry, Faculty of Medicine, H-6720 Szeged, Dóm tér 8 (Hungary); Buzás, Norbert [Department of Health Economics, Faculty of Medicine, University of Szeged, H-6720 Szeged, Szőkefalvi-Nagy Béla u. 6 (Hungary); Dékány, Imre, E-mail: i.dekany@chem.u-szeged.hu [MTA-SZTE Supramolecular and Nanostructured Materials Research Group, Department of Medical Chemistry, Faculty of Medicine, H-6720 Szeged, Dóm tér 8 (Hungary)

    2016-05-15

    Highlights: • Surface reactivity of TiO{sub 2} and Ag–TiO{sub 2} nanohybrid films were tested by photooxidation. • Photocatalyst–bacteria interactions were defined by surface charge determination. • Higher surface charge induces stronger adhesion between the bacteria and the NPs. • Inactivation of GR+/GR− bacteria by hydroxyl radicals depends on cell wall structure. • The cell wall degradation of bacteria was proven with TEM and fluorescence studies - Abstract: The aim of this study was to develop photoreactive surface coatings, possessing antibacterial properties and can be activated under visible light illumination (λ{sub max} = 405 nm) using LED-light source. The photocatalytically active titanium dioxide (TiO{sub 2}) was functionalized with silver nanoparticles (Ag NPs) and immobilized in polyacrylate based nanohybrid thin film in order to facilitate visible light activity (λ{sub Ag/TiO2,max} = 500 nm). First, the photocatalytic activity was modelled by following ethanol vapor degradation. The plasmonic functionalization resulted in 15% enhancement of the activity compared to pure TiO{sub 2}. The photoreactive antimicrobial (5 log reduction of cfu in 2 h) surface coatings are able to inactivate clinically relevant pathogen strains (methicillin resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) within short time (60–120 min) due to the formed and quantified reactive oxygen species (ROS). The existence of electrostatic interactions between the negatively charged bacteria (from −0.89 to −3.19 μeq/10{sup 9} cfu) and positively charged photocatalyst particles (in the range of +0.38 and +12.3 meq/100 g) was also proven by charge titration measurements. The surface inactivation of the bacteria and the photocatalytic degradation of the cell wall component were also confirmed by fluorescence and transmission electron microscopic observations, respectively. According to the results an effective sterilizing system and

  4. Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract.

    Science.gov (United States)

    Kline, Kimberly A; Lewis, Amanda L

    2016-04-01

    Gram-positive bacteria are a common cause of urinary-tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI.

  5. Selective bowel decontamination results in gram-positive translocation.

    Science.gov (United States)

    Jackson, R J; Smith, S D; Rowe, M I

    1990-05-01

    Colonization by enteric gram-negative bacteria with subsequent translocation is believed to be a major mechanism for infection in the critically ill patient. Selective bowel decontamination (SBD) has been used to control gram-negative infections by eliminating these potentially pathogenic bacteria while preserving anaerobic and other less pathogenic organisms. Infection with gram-positive organisms and anaerobes in two multivisceral transplant patients during SBD led us to investigate the effect of SBD on gut colonization and translocation. Twenty-four rats received enteral polymixin E, tobramycin, amphotericin B, and parenteral cefotaxime for 7 days (PTA + CEF); 23 received parenteral cefotaxime alone (CEF), 19 received the enteral antibiotics alone (PTA), 21 controls received no antibiotics. Cecal homogenates, mesenteric lymph node (MLN), liver, and spleen were cultured. Only 8% of the PTA + CEF group had gram-negative bacteria in cecal culture vs 52% CEF, 84% PTA, and 100% in controls. Log Enterococcal colony counts were higher in the PTA + CEF group (8.0 + 0.9) vs controls (5.4 + 0.4) P less than 0.01. Translocation of Enterococcus to the MLN was significantly increased in the PTA + CEF group (67%) vs controls (0%) P less than 0.01. SBD effectively eliminates gram-negative organisms from the gut in the rat model. Overgrowth and translocation of Enterococcus suggests that infection with gram-positive organisms may be a limitation of SBD.

  6. Daptomycin treatment in Gram-positive vascular graft infections

    Directory of Open Access Journals (Sweden)

    Francisco Arnaiz de las Revillas

    2018-03-01

    Full Text Available Background: Daptomycin is a bactericidal antibiotic approved for the treatment of skin and soft tissue infections and right-side endocarditis. However, there is a lack of published data outlining its usefulness in vascular graft infections (VGI. The aim of this study was to describe the clinical experience of daptomycin use in the treatment of VGI caused by Gram-positive bacteria. Methods: This was a retrospective cohort study of patients diagnosed with VGI receiving daptomycin at a tertiary care hospital during the period January 2010 to December 2012. Results: Of a total 1066 consecutive patients who had undergone vascular grafts (VG, 25 were diagnosed with VGI. Fifteen of these patients (11 prosthetic VG, three autologous VG, one both types received daptomycin (median dose 6.7 mg/kg/day, range 4.1–7.1 mg/kg/day; median age 69 years, range 45–83 years; 80% male. The infected bypass was removed in 13 cases. The most common reason for selecting daptomycin was kidney failure (53%. The Gram-positive organisms isolated were coagulase-negative Staphylococcus (n = 10, Staphylococcus aureus (n = 3 (two methicillin-resistant S. aureus, Enterococcus faecium (n = 2, and Enterococcus faecalis (n = 1. The mean follow-up was 69 months (interquartile range 48–72 months. Ten patients (66.7% achieved complete healing of the VGI. A recurrence of the infection was observed in 100% of patients in whom the bypass was not removed. Among patients who did not achieve complete healing, one needed a supracondylar amputation and one died as a consequence of infection. Five patients received treatment with rifampicin in addition to daptomycin and they were all cured. Conclusions: The use of daptomycin and surgery for Gram-positive VGI was effective and well tolerated, and this may be a good alternative for the treatment of VGI in patients with peripheral arterial disease in whom renal insufficiency is common. Keywords: Daptomycin, Gram-positive, Vascular

  7. Single Intravenous Dose of Oritavancin for Treatment of Acute Skin and Skin Structure Infections Caused by Gram-Positive Bacteria: Summary of Safety Analysis from the Phase 3 SOLO Studies.

    Science.gov (United States)

    Corey, G Ralph; Loutit, Jeffery; Moeck, Greg; Wikler, Matthew; Dudley, Michael N; O'Riordan, William

    2018-04-01

    Oritavancin is a lipoglycopeptide with bactericidal activity against Gram-positive organisms. Its rapid concentration-dependent bactericidal activity and long elimination half-life allow single-dose treatment of acute bacterial skin and skin structure infections (ABSSSI). SOLO I and SOLO II were randomized, double-blind studies evaluating the efficacy and safety of a single 1,200-mg intravenous (i.v.) dose of oritavancin versus twice-daily i.v. vancomycin for 7 to 10 days in ABSSSI patients. Safety data from both studies were pooled for safety analysis. The database comprised pooled safety data for 976 oritavancin-treated patients and 983 vancomycin-treated patients. The incidences of adverse events, serious adverse events, and discontinuations due to adverse events were similar for oritavancin (55.3, 5.8, and 3.7%, respectively) and vancomycin (56.9, 5.9, and 4.2%, respectively). The median time to onset (3.8 days versus 3.1 days, respectively) and the duration (3.0 days for both groups) of adverse events were also similar between the two groups. The most frequently reported events were nausea, headache, and vomiting. Greater than 90% of all events were mild or moderate in severity. There were slightly more infections and infestations, abscesses or cellulitis, and hepatic and cardiac adverse events in the oritavancin group; however, more than 80% of these events were mild or moderate. Subgroup analyses did not identify clinically meaningful differences in the incidence of adverse events attributed to oritavancin. A single 1,200-mg dose of oritavancin was well tolerated and had a safety profile similar to that of twice-daily vancomycin. The long elimination half-life of oritavancin compared to that of vancomycin did not result in a clinically meaningful delay to the onset or prolongation of adverse events. (This study has been registered at ClinicalTrials.gov under registration no. NCT01252719 and NCT01252732.). Copyright © 2018 American Society for Microbiology.

  8. Inhibition spectrum studies of microthecin and other anhydrofructose derivatives using selected strains of Gram-positive and –negative bacteria, yeast and moulds, and investigation of the cytotoxicity of microthecin to malignant blood cell lines

    DEFF Research Database (Denmark)

    Fiskesund, R.; Thomas, L.V.; Schobert, M.

    2009-01-01

    Aims: To prepare 1,5-anhydro-d-fructose (AF) derivatives, test their microbial inhibition spectrum, and to further examine the most effective AF derivative against Pseudomonas aeruginosa and malignant blood cell lines. Methods and Results: Microthecin and nine other AF derivatives were synthesized...... both GP and GN bacteria, including Ps. aeruginosa. Further tests with three malignant blood cell lines (Mutu, Ramos, Raji) and one normal cell line indicated that microthecin was a cell toxin, with a cell mortality >85% at 50 ppm. The other nine AF derivatives demonstrated low or no antimicrobial...... activity. Conclusions: Microthecin was active 100–2000 ppm against GP and GN bacteria including Ps. aeruginosa, but was inactive against yeasts and moulds. Microthecin was also a cytotoxin to some mammalian cell lines. Significance and Impact of the Study: Microthecin might have potential for development...

  9. Clinical update on linezolid in the treatment of Gram-positive bacterial infections

    Science.gov (United States)

    Ager, Sally; Gould, Kate

    2012-01-01

    Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs. PMID:22787406

  10. The complete genome sequence of the Gram-positive bacterium Bacillus subtilis

    NARCIS (Netherlands)

    Kunst, F; Ogasawara, N; Moszer, [No Value; Albertini, AM; Alloni, G; Azevedo, [No Value; Bertero, MG; Bessieres, P; Bolotin, A; Borchert, S; Borriss, R; Boursier, L; Brans, A; Brignell, SC; Bron, S; Brouillet, S; Bruschi, CV; Caldwell, B; Capuano, [No Value; Carter, NM; Choi, SK; Codani, JJ; Connerton, IF; Cummings, NJ; Daniel, RA; Denizot, F; Devine, KM; Dusterhoft, A; Ehrlich, SD; Emmerson, PT; Entian, KD; Errington, J; Fabret, C; Ferrari, E; Foulger, D; Fujita, M; Fujita, Y; Fuma, S; Galizzi, A; Galleron, N; Ghim, SY; Glaser, P; Goffeau, A; Golightly, EJ; Grandi, G; Guiseppi, G; Guy, BJ; Haga, K; Haiech, J; Harwood, CR; Henaut, A; Hilbert, H; Holsappel, S; Hosono, S; Hullo, MF; Itaya, M; Jones, L; Joris, B; Karamata, D; Kasahara, Y; KlaerrBlanchard, M; Klein, C; Kobayashi, Y; Koetter, P; Koningstein, G; Krogh, S; Kumano, M; Kurita, K; Lapidus, A; Lardinois, S; Lauber, J; Lazarevic, [No Value; Lee, SM; Levine, A; Liu, H; Masuda, S; Mauel, C; Medigue, C; Medina, N; Mellado, RP; Mizuno, M; Moestl, D; Nakai, S; Noback, M; Noone, D; OReilly, M; Ogawa, K; Ogiwara, A; Oudega, B; Park, SH; Parro, [No Value; Pohl, TM; Portetelle, D; Porwollik, S; Prescott, AM; Presecan, E; Pujic, P; Purnelle, B; Rapoport, G; Rey, M; Reynolds, S; Rieger, M; Rivolta, C; Rocha, E; Roche, B; Rose, M; Sadaie, Y; Sato, T; Scanlan, E; Schleich, S; Schroeter, R; Scoffone, F; Sekiguchi, J; Sekowska, A; Seror, SJ; Serror, P; Shin, BS; Soldo, B; Sorokin, A; Tacconi, E; Takagi, T; Takahashi, H; Takemaru, K; Takeuchi, M; Tamakoshi, A; Tanaka, T; Terpstra, P; Tognoni, A; Tosato, [No Value; Uchiyama, S; Vandenbol, M; Vannier, F; Vassarotti, A; Viari, A; Wambutt, R; Wedler, E; Wedler, H; Weitzenegger, T; Winters, P; Wipat, A; Yamamoto, H; Yamane, K; Yasumoto, K; Yata, K; Yoshida, K; Yoshikawa, HF; Zumstein, E; Yoshikawa, H; Danchin, A

    1997-01-01

    Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been

  11. High-level fluorescence labeling of gram-positive pathogens.

    Directory of Open Access Journals (Sweden)

    Simone Aymanns

    Full Text Available Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10-50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration.

  12. Streptococcus mutans: a new Gram-positive paradigm?

    Science.gov (United States)

    Quivey, Robert G.; Koo, Hyun; Abranches, Jacqueline

    2013-01-01

    Despite the enormous contributions of the bacterial paradigms Escherichia coli and Bacillus subtilis to basic and applied research, it is well known that no single organism can be a perfect representative of all other species. However, given that some bacteria are difficult, or virtually impossible, to cultivate in the laboratory, that some are recalcitrant to genetic and molecular manipulation, and that others can be extremely dangerous to manipulate, the use of model organisms will continue to play an important role in the development of basic research. In particular, model organisms are very useful for providing a better understanding of the biology of closely related species. Here, we discuss how the lifestyle, the availability of suitable in vitro and in vivo systems, and a thorough understanding of the genetics, biochemistry and physiology of the dental pathogen Streptococcus mutans have greatly advanced our understanding of important areas in the field of bacteriology such as interspecies biofilms, competence development and stress responses. In this article, we provide an argument that places S. mutans, an organism that evolved in close association with the human host, as a novel Gram-positive model organism. PMID:23393147

  13. FORMALDEHYDE DISMUTASE ACTIVITIES IN GRAM-POSITIVE BACTERIA OXIDIZING METHANOL

    NARCIS (Netherlands)

    BYSTRYKH, LV; GOVORUKHINA, NI; VANOPHEM, PW; HEKTOR, HJ; DIJKHUIZEN, L; DUINE, JA; Govorukhina, Natalya; Ophem, Peter W. van; Duine, Johannis A.

    Extracts of methanol-grown cells of Amycolatopsis methanolica and Mycobacterium gastri oxidized methanol and ethanol with concomitant reduction of N,N'-dimethyl-4-nitrosoaniline (NDMA). Anion-exchange chromatography revealed the presence of a single enzyme able to catalyse this activity in methanol-

  14. Diverse Gram-positive bacteria identified from raw and pasteurized ...

    African Journals Online (AJOL)

    tion practices associated with milking and storage equipment. ... materials, various ingredients added to dairy products and dairy farm work- ers. ... 7°E, respectively and 2200 meter above sea level, respectively. The an- ... storage facilities, and shelf life of the pasteurized milk. ... transferred into a sterile screw capped bottle.

  15. c-di-GMP Regulates Various Phenotypes and Insecticidal Activity of Gram-Positive Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Yang Fu

    2018-02-01

    Full Text Available C-di-GMP has been well investigated to play significant roles in the physiology of many Gram-negative bacteria. However, its effect on Gram-positive bacteria is less known. In order to more understand the c-di-GMP functions in Gram-positive bacteria, we have carried out a detailed study on the c-di-GMP-metabolizing enzymes and their physiological functions in Bacillus thuringiensis, a Gram-positive entomopathogenic bacterium that has been applied as an insecticide successfully. We performed a systematic study on the ten putative c-di-GMP-synthesizing enzyme diguanylate cyclases (DGCs and c-di-GMP-degrading enzyme phosphodiesterases (PDEs in B. thuringiensis BMB171, and artificially elevated the intracellular c-di-GMP level in BMB171 by deleting one or more pde genes. We found increasing level of intracellular c-di-GMP exhibits similar activities as those in Gram-negative bacteria, including altered activities in cell motility, biofilm formation, and cell-cell aggregation. Unexpectedly, we additionally found a novel function exhibited by the increasing level of c-di-GMP to promote the insecticidal activity of this bacterium against Helicoverpa armigera. Through whole-genome transcriptome profile analyses, we found that 4.3% of the B. thuringiensis genes were differentially transcribed when c-di-GMP level was increased, and 77.3% of such gene products are involved in some regulatory pathways not reported in other bacteria to date. In summary, our study represents the first comprehensive report on the c-di-GMP-metabolizing enzymes, their effects on phenotypes, and the transcriptome mediated by c-di-GMP in an important Gram-positive bacterium.

  16. Novel Antimicrobial Peptides That Inhibit Gram Positive Bacterial Exotoxin Synthesis

    Science.gov (United States)

    Merriman, Joseph A.; Nemeth, Kimberly A.; Schlievert, Patrick M.

    2014-01-01

    Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and α-globin and β-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized α-globin chain peptides, synthetic variants of α-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges. PMID:24748386

  17. Procalcitonin levels in gram-positive, gram-negative, and fungal bloodstream infections.

    Science.gov (United States)

    Leli, Christian; Ferranti, Marta; Moretti, Amedeo; Al Dhahab, Zainab Salim; Cenci, Elio; Mencacci, Antonella

    2015-01-01

    Procalcitonin (PCT) can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8 ng/mL, interquartile range (IQR) 3.4-44.1) bacteremias was significantly higher than in Gram-positive (2.1 ng/mL, IQR 0.6-7.6) or fungal (0.5 ng/mL, IQR 0.4-1) infections (P Gram-negatives from Gram-positives at the best cut-off value of 10.8 ng/mL and an AUC of 0.944 (95% CI 0.919-0.969, P Gram-negatives from fungi at the best cut-off of 1.6 ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1 ng/mL, IQR 5.9-48.5 versus 3.5 ng/mL, IQR 0.8-21.5; P Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies.

  18. Linezolid: a promising option in the treatment of Gram-positives.

    Science.gov (United States)

    Zahedi Bialvaei, Abed; Rahbar, Mohammad; Yousefi, Mehdi; Asgharzadeh, Mohammad; Samadi Kafil, Hossein

    2017-02-01

    Linezolid, an oxazolidinone antimicrobial agent that acts by inhibiting protein synthesis in a unique fashion, is used in the treatment of community-acquired pneumonia, skin and soft-tissue infections and other infections caused by Gram-positive bacteria including VRE and methicillin-resistant staphylococci. Currently, linezolid resistance among these pathogens remains low, commonly linezolid susceptibility testing for this important agent and should be taken into account when considering its therapeutic use. Considering the importance of linezolid in the treatment of infections caused by Gram-positive bacteria, this review was undertaken to optimize the clinical use of this antibiotic. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Cellular reprogramming by gram-positive bacterial components: a review.

    LENUS (Irish Health Repository)

    Buckley, Julliette M

    2012-02-03

    LPS tolerance has been the focus of extensive scientific and clinical research over the last several decades in an attempt to elucidate the sequence of changes that occur at a molecular level in tolerized cells. Tolerance to components of gram-positive bacterial cell walls such as bacterial lipoprotein and lipoteichoic acid is a much lesser studied, although equally important, phenomenon. This review will focus on cellular reprogramming by gram-positive bacterial components and examines the alterations in cell surface receptor expression, changes in intracellular signaling, gene expression and cytokine production, and the phenomenon of cross-tolerance.

  20. Inhibitory effect of beta-pinene, alpha-pinene and eugenol on the growth of potential infectious endocarditis causing Gram-positive bacteria Efeito inibitório de eugenol, beta-pineno e alfa-pineno sobre o crescimento de bactérias Gram-positivas potencialmente causadoras de endocardite infecciosa

    Directory of Open Access Journals (Sweden)

    Aristides Medeiros Leite

    2007-03-01

    Full Text Available This study was led with the purpose of evaluating the effectiveness of eugenol, beta-pinene and alpha-pinene in inhibiting the growth of potential infectious endocarditis causing gram-positive bacteria. The phytochemicals Minimum Inhibitory Concentration-MIC was determined by solid medium diffusion procedure, while the interference of the MIC values on the bacterial cell viability was performed by viable cells count. Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae and S. pyogenes strains were used as test microorganisms. The assayed phytochemicals showed effectiveness in inhibiting all assayed bacteria strains presenting MIC values between 2.5 and 40 µL/mL. Eugenol showed the lowest MIC values which were between 2.5 and 5 µL/mL for the most bacteria strains. MIC values found to the phytochemicals were able to inhibit the cell viability of S. aureus providing a total elimination of the bacteria inoculum in a maximum time of 24 hours of exposure. These data showed the interesting antibacterial property of the assayed phytochemicals and support their possible and rational use in the antimicrobial therapy.Este estudo foi conduzido com a proposta de avaliar a efetividade de eugenol, beta-pineno e alfa-pineno em inibir o crescimento de cepas de bactérias Gram-positivas potencialmente causadoras de endocardite infecciosa. A Concentração Inibitória Mínima-CIM dos fitoconstituintes foi determinada através do método de difusão em meio sólido, enquanto a interferência da CIM sobre a viabilidade celular bacteriana foi avaliada através da contagem de células viáveis. Cepas de Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae e S. pyogenes foram utilizadas como microrganismos teste nos ensaios antimicrobianos. Os fitoconstituintes ensaiados mostraram efetividade em inibir todas as cepas bacterianas utilizadas como microrganismos testes apresentando valores de CIM entre 2.5 e 40 µL/mL. Eugenol apresentou os menores

  1. Endocarditis : Effects of routine echocardiography during Gram-positive bacteraemia

    NARCIS (Netherlands)

    Vos, F J; Bleeker-Rovers, C P; Sturm, P D; Krabbe, P F M; van Dijk, A P J; Oyen, W J G; Kullberg, B J

    2011-01-01

    BACKGROUND: Despite firm recommendations to perform echocardiography in high-risk patients with Gram-positive bacteraemia, routine echocardiography is not embedded in daily practice in many settings. The aim of this study was to evaluate whether a regime including routine echocardiography results in

  2. Analysis of the composition of Brazilian propolis extracts by chromatography and evaluation of their in vitro activity against gram-positive bacteria Análise da composição de extratos de própolis brasileiros por cromatografia e avaliação de sua atividade in vitro sobre bactérias

    Directory of Open Access Journals (Sweden)

    Alexandra C. H. F. Sawaya

    2004-06-01

    Full Text Available Brazilian propolis from São Paulo state was submitted to extraction using several solvents, resulting in extracts with different composition. These extracts were submitted to Thin Layer Chromatography (TLC. Bioauthographic analysis of the TLC plates identified fractions with inhibitory activity, which were then analysed by High Performance Liquid Chromatography (HPLC. In vitro assays, commonly used to evaluate the activity of propolis against Gram-positive bacteria, were compared to determine which rendered the most consistent results. The bactericidal activity of these extracts were analysed by Serial Dilution in Tubes and Agar Plate Diffusion. Serial Dilution in Tubes obtained the most consistent results, with the Minimal Bactericidal Concentration of the extracts ranging between 2.5 and 20.0 mg/mL, for the species of Gram-positive bacteria tested. The results of the Agar Plate Diffusion were directly proportional to the hydro-solubility of the extracts and did not evaluate their bactericidal activity correctly. The bactericidal activity of this sample of propolis was due to the combined effect of several components that were identified by HPLC and were best extracted using 50% ethanol as a solvent.Própolis brasileira, proveniente do estado de São Paulo, foi submetida à extração usando vários solventes, resultando em extratos com diferentes composições. Estes extratos foram submetidos à Cromatografia em Camada Delgada (CCD. Análise bioautográfica das placas de CCD permitiu identificar as frações com atividade antimicrobiana, que foram então analisadas por Cromatografia Líquida de Alta Eficiência (CLAE. Ensaios in vitro freqüentemente utilizados para avaliar a atividade de própolis frente a bactérias Gram-positivas foram comparados para determinar qual renderia os resultados mais consistentes. A atividade bactericida destes extratos foi analisada por Diluição Seriada em Tubos e por testes de Difusão em Agar. O método de

  3. Blue green alga mediated synthesis of gold nanoparticles and its antibacterial efficacy against Gram positive organisms

    Energy Technology Data Exchange (ETDEWEB)

    Uma Suganya, K.S. [Centre for Ocean Research, Sathyabama University, Chennai 600 119 (India); Govindaraju, K., E-mail: govindtu@gmail.com [Centre for Ocean Research, Sathyabama University, Chennai 600 119 (India); Ganesh Kumar, V.; Stalin Dhas, T.; Karthick, V. [Centre for Ocean Research, Sathyabama University, Chennai 600 119 (India); Singaravelu, G. [Nanoscience Division, Department of Zoology, Thiruvalluvar University, Vellore 632115 (India); Elanchezhiyan, M. [Department of Microbiology, Dr ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Chennai 600113 (India)

    2015-02-01

    Biofunctionalized gold nanoparticles (AuNPs) play an important role in design and development of nanomedicine. Synthesis of AuNPs from biogenic materials is environmentally benign and possesses high bacterial inhibition and bactericidal properties. In the present study, blue green alga Spirulina platensis protein mediated synthesis of AuNPs and its antibacterial activity against Gram positive bacteria is discussed. AuNPs were characterized using Ultraviolet–visible (UV–vis) spectroscopy, Fluorescence spectroscopy, Fourier Transform-Infrared (FTIR) spectroscopy, Raman spectroscopy, High Resolution-Transmission Electron Microscopy (HR-TEM) and Energy Dispersive X-ray analysis (EDAX). Stable, well defined AuNPs of smaller and uniform shape with an average size of ∼ 5 nm were obtained. The antibacterial efficacy of protein functionalized AuNPs were tested against Gram positive organisms Bacillus subtilis and Staphylococcus aureus. - Highlights: • Size controlled synthesis of gold nanoparticles from blue green alga Spirulina platensis • Stability of gold nanoparticles at different temperatures • Potent antibacterial efficacy against Gram positive organisms.

  4. Procalcitonin Levels in Gram-Positive, Gram-Negative, and Fungal Bloodstream Infections

    Directory of Open Access Journals (Sweden)

    Christian Leli

    2015-01-01

    Full Text Available Procalcitonin (PCT can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8 ng/mL, interquartile range (IQR 3.4–44.1 bacteremias was significantly higher than in Gram-positive (2.1 ng/mL, IQR 0.6–7.6 or fungal (0.5 ng/mL, IQR 0.4–1 infections (P<0.0001. Receiver operating characteristic analysis showed an area under the curve (AUC for PCT of 0.765 (95% CI 0.725–0.805, P<0.0001 in discriminating Gram-negatives from Gram-positives at the best cut-off value of 10.8 ng/mL and an AUC of 0.944 (95% CI 0.919–0.969, P<0.0001 in discriminating Gram-negatives from fungi at the best cut-off of 1.6 ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1 ng/mL, IQR 5.9–48.5 versus 3.5 ng/mL, IQR 0.8–21.5; P<0.0001. This study suggests that PCT may be of value to distinguish Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies.

  5. The Mechanisms of Virulence Regulation by Small Noncoding RNAs in Low GC Gram-Positive Pathogens

    Directory of Open Access Journals (Sweden)

    Stephanie Pitman

    2015-12-01

    Full Text Available The discovery of small noncoding regulatory RNAs (sRNAs in bacteria has grown tremendously recently, giving new insights into gene regulation. The implementation of computational analysis and RNA sequencing has provided new tools to discover and analyze potential sRNAs. Small regulatory RNAs that act by base-pairing to target mRNAs have been found to be ubiquitous and are the most abundant class of post-transcriptional regulators in bacteria. The majority of sRNA studies has been limited to E. coli and other gram-negative bacteria. However, examples of sRNAs in gram-positive bacteria are still plentiful although the detailed gene regulation mechanisms behind them are not as well understood. Strict virulence control is critical for a pathogen’s survival and many sRNAs have been found to be involved in that process. This review outlines the targets and currently known mechanisms of trans-acting sRNAs involved in virulence regulation in various gram-positive pathogens. In addition, their shared characteristics such as CU interaction motifs, the role of Hfq, and involvement in two-component regulators, riboswitches, quorum sensing, or toxin/antitoxin systems are described.

  6. Metabolic versatility of Gram-positive microbial isolates from contaminated river sediments

    International Nuclear Information System (INIS)

    Narancic, Tanja; Djokic, Lidija; Kenny, Shane T.; O’Connor, Kevin E.; Radulovic, Vanja; Nikodinovic-Runic, Jasmina; Vasiljevic, Branka

    2012-01-01

    Highlights: ► Thirty-four isolated Gram-positive bacteria could degrade wide range of aromatic pollutants. ► Nine isolates could grow in the presence of extremely high levels of heavy metals. ► Twelve isolates accumulated polyphosphate, 3 polyhydroxybutyrate, 4 exopolysaccharides. ► The incidence of multiple antibiotic resistance markers among isolates was low. - Abstract: Gram-positive bacteria from river sediments affected by the proximity of a petrochemical industrial site were isolated and characterized with respect to their ability to degrade a wide range of aromatic compounds. In this study we identified metabolically diverse Gram-positive bacteria capable of growth on wide range aromatic compounds in the presence of heavy metals and with the ability to accumulate biopolymers. Thirty-four isolates that were able to use 9 or more common aromatic pollutants, such as benzene, biphenyl, naphthalene etc. as a sole source of carbon and energy included members of Bacillus, Arthrobacter, Rhodococcus, Gordonia, Streptomyces, and Staphylococcus genus. Rhodococcus sp. TN105, Gordonia sp. TN103 and Arthrobacter sp. TN221 were identified as novel strains. Nine isolates were able to grow in the presence of one or more metals (mercury, cadmium, nickel) at high concentration (100 mM). Seven isolates could degrade 15 different aromatic compounds and could grow in the presence of one or more heavy metals. Two of these isolates were resistant to multiple antibiotics including erythromycin and nalidixic acid. One third of isolates could accumulate at least one biopolymer. Twelve isolates (mainly Bacillus sp. and Arthrobacter sp.) accumulated polyphosphate, 3 Bacillus sp. accumulated polyhydroxybutyrate, while 4 isolates could accumulate exopolysaccharides.

  7. Daptomycin: a novel lipopeptide antibiotic against Gram-positive pathogens

    Directory of Open Access Journals (Sweden)

    Andres Beiras-Fernandez

    2010-08-01

    Full Text Available Andres Beiras-Fernandez1,*, Ferdinand Vogt1,*, Ralf Sodian1, Florian Weis21Department of Cardiac Surgery, University Hospital Großhadern, Ludwig-Maximilian-University, Munich, Germany; 2Department of Anesthesiology, University Hospital Großhadern, Ludwig-Maximilian-University, Munich, Germany *Andres Beiras-Fernandez and Ferdinand Vogt contributed equally to this paperAbstract: The aim of this review is to summarize the historical background of drug resistance of Gram-positive pathogens as well as to describe in detail the novel lipopeptide antibiotic daptomycin. Pharmacological and pharmacokinetic aspects are reviewed and the current clinical use of daptomycin is presented. Daptomycin seems to be a reliable drug in the treatment of complicated skin and skin structure infections, infective right-sided endocarditis, and bacteremia caused by Gram-positive agents. Its unique mechanism of action and its low resistance profile, together with its rapid bactericidal action make it a favorable alternative to vancomycin in multi-drug resistant cocci. The role of daptomycin in the treatment of prosthetic material infections, osteomyelitis, and urogenital infections needs to be evaluated in randomized clinical trials.Keywords: daptomycin, multi-drug resistance, methicillin-resistant Staphylococcus aureus (MRSA, pneumonia, urinary tract infection, left-sided endocarditis

  8. Antimicrobial-Resistance Genetic Markers in Potentially Pathogenic Gram Positive Cocci Isolated from Brazilian Soft Cheese.

    Science.gov (United States)

    Resende, Juliana Alves; Fontes, Cláudia Oliveira; Ferreira-Machado, Alessandra Barbosa; Nascimento, Thiago César; Silva, Vânia Lúcia; Diniz, Cláudio Galuppo

    2018-02-01

    Although most Brazilian dairy products meet high technological standards, there are quality issues regarding milk production, which may reduce the final product quality. Several microbial species may contaminate milk during manufacture and handling. If antimicrobial usage remains uncontrolled in dairy cattle, the horizontal transfer of antimicrobial resistance genes in foodstuffs may be of particular concern for both food producers and dairy industry. This study focused on the evaluation of putative Gram positive cocci in Minas cheese and of antimicrobial and biocide resistance genes among the isolated bacteria. Representative samples of 7 different industrially trademarked Minas cheeses (n = 35) were processed for selective culture and isolation of Gram positive cocci. All isolated bacteria were identified by DNA sequencing of the 16S rRNA gene. Antimicrobial resistance genes were screened by PCR. Overall, 208 strains were isolated and identified as follows: Enterococcus faecalis (47.6%), Macrococcus caseolyticus (18.3%), Enterococcus faecium (11.5%), Enterococcus caseliflavus (7.7%), Staphylococcus haemolyticus (7.2%), Staphylococcus aureus (4.3%), Staphylococcus epidermidis (2.9%), and Enterococcus hirae (0.5%). The genetic markers mecA (78.0%) and smr (71.4%) were the most prevalent, but others were also detected, such as blaZ (65.2%), msrA (60.9%), msrB (46.6%), linA (54.7%), and aacA-aphD (47.6%). The occurrence of opportunist pathogenic bacteria harboring antimicrobial resistance markers in the cheese samples are of special concern, since these bacteria are not considered harmful contaminating agents according to the Brazilian sanitary regulations. However, they are potentially pathogenic bacteria and the cheese may be considered a reservoir for antimicrobial resistance genes available for horizontal transfer through the food chain, manufacturing personnel and consumers. © 2018 Institute of Food Technologists®.

  9. Fighting infections due to multidrug-resistant Gram-positive pathogens.

    Science.gov (United States)

    Cornaglia, G

    2009-03-01

    Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process.

  10. DMPD: Cellular reprogramming by gram-positive bacterial components: a review. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16885502 Cellular reprogramming by gram-positive bacterial components: a review. Bu...(.csml) Show Cellular reprogramming by gram-positive bacterial components: a review. PubmedID 16885502 Title... Cellular reprogramming by gram-positive bacterial components: a review. Authors

  11. Bioengineered nisin A derivatives with enhanced activity against both Gram positive and Gram negative pathogens.

    Directory of Open Access Journals (Sweden)

    Des Field

    Full Text Available Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G, with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria.

  12. Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens

    Science.gov (United States)

    Field, Des; Begley, Maire; O’Connor, Paula M.; Daly, Karen M.; Hugenholtz, Floor; Cotter, Paul D.; Hill, Colin; Ross, R. Paul

    2012-01-01

    Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria. PMID:23056510

  13. Limitations in the use of Drosophila melanogaster as a model host for gram-positive bacterial infection

    DEFF Research Database (Denmark)

    Jensen, Rikke Lind; Pedersen, K.S.; Loeschcke, V

    2007-01-01

    resistance respectively, were subjected to infection by L. monocytogenes, S. aureus and E. coli. Mortality rates were comparable with that of the Oregon R strain. Conclusions: Use of the injection method shows the limitation of D. melanogaster as a model host for gram-positive bacteria as opportunistic......Aims: To examine sensitivities of various Drosophila melanogaster strains towards human pathogenic and nonpathogenic gram-positive bacteria. Methods and Results: The D. melanogaster Oregon R strain was infected by injecting the thorax with a needle containing Escherichia coli (negative control...... with the negative control. Infection with L. innocua, B. subtilis or C. maltaromaticum also resulted in a high fly mortality, whereas Lact. plantarum and P. acidilactici resulted in a slightly increased mortality. Four additional D. melanogaster lines, three of which had been selected for heat, cold and desiccation...

  14. Extracellular Electron Transfer Mediated by Flavins in Gram-positive Bacillus sp. WS-XY1 and Yeast Pichia stipitis

    International Nuclear Information System (INIS)

    Wu, Song; Xiao, Yong; Wang, Lu; Zheng, Yue; Chang, Kenlin; Zheng, Zhiyong; Yang, Zhaohui; Varcoe, John R.; Zhao, Feng

    2014-01-01

    Extracellular electron transfer (EET) of microorganisms represents a communicative bridge between the interior and exterior of the cells. Most prior EET studies have focused on Gram-negative bacteria. However, fungi and Gram-positive bacteria, that contain dense cellular walls, have rarely been reported. Herein, two model dense cell wall microorganisms (Bacillus sp. WS-XY1 and the yeast Pichia stipitis) were identified to be electrochemically active. Further analysis indicated that the two microorganisms were able to secrete flavins to mediate their EET. The discovery, that dense cell wall containing microorganisms can undertake mediated EET, adds to the body of knowledge towards building a comprehensive understanding of biogeochemical and bioelectrical processes

  15. Gram-positive bacterial lipoglycans based on a glycosylated diacylglycerol lipid anchor are microbe-associated molecular patterns recognized by TLR2.

    Directory of Open Access Journals (Sweden)

    Landry Blanc

    Full Text Available Innate immune recognition is the first line of host defense against invading microorganisms. It is a based on the detection, by pattern recognition receptors (PRRs, of invariant molecular signatures that are unique to microorganisms. TLR2 is a PRR that plays a major role in the detection of Gram-positive bacteria by recognizing cell envelope lipid-linked polymers, also called macroamphiphiles, such as lipoproteins, lipoteichoic acids and mycobacterial lipoglycans. These microbe-associated molecular patterns (MAMPs display a structure based on a lipid anchor, being either an acylated cysteine, a glycosylated diacylglycerol or a mannosyl-phosphatidylinositol respectively, and having in common a diacylglyceryl moiety. A fourth class of macroamphiphile, namely lipoglycans, whose lipid anchor is made, as for lipoteichoic acids, of a glycosylated diacylglycerol unit rather than a mannosyl-phosphatidylinositol, is found in Gram-positive bacteria and produced by certain Actinobacteria, including Micrococcus luteus, Stomatococcus mucilaginosus and Corynebacterium glutamicum. We report here that these alternative lipoglycans are also recognized by TLR2 and that they stimulate TLR2-dependant cytokine production, including IL-8, TNF-α and IL-6, and cell surface co-stimulatory molecule CD40 expression by a human macrophage cell line. However, they differ by their co-receptor requirement and the magnitude of the innate immune response they elicit. M. luteus and S. mucilaginosus lipoglycans require TLR1 for recognition by TLR2 and induce stronger responses than C. glutamicum lipoglycan, sensing of which by TLR2 is dependent on TLR6. These results expand the repertoire of MAMPs recognized by TLR2 to lipoglycans based on a glycosylated diacylglycerol lipid anchor and reinforce the paradigm that macroamphiphiles based on such an anchor, including lipoteichoic acids and alternative lipoglycans, induce TLR2-dependant innate immune responses.

  16. Gram-positive rods prevailing in teeth with apical periodontitis undergoing root canal treatment.

    Science.gov (United States)

    Chávez de Paz, L E; Molander, A; Dahlén, G

    2004-09-01

    To identify Gram-positive rods from root canals of teeth with apical periodontitis and to examine their associations with other species. Consecutive root canal samples (RCSs) from 139 teeth undergoing root canal treatment were analyzed prospectively for cultivable microbes. Gram-positive rods in the first RCS submitted after chemo-mechanical preparation were categorised to genus level by selective media and gas-liquid chromatography (GLC), and identified to species level by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Associations between organisms were measured by odds ratios (OR). In the first samples submitted a total of 158 Gram-positive rods, 115 Gram-positive cocci, 26 Gram-negative rods and 9 Gram-negative cocci, were identified. At genus levels Gram-positive rods were classified into: Lactobacillus spp. (38%), Olsenella spp. (18%), Propionibacterium spp. (13%), Actinomyces spp. (12%), Bifidobacterium spp. (13%) and Eubacterium spp. (6%). The most frequent species were Olsenella uli, Lactobacillus paracasei and Propionibacterium propionicum. In subsequent samples taken during treatment, Gram-positive rods were also identified, although the number of strains was considerably reduced. Positive associations were observed between members of the genus lactobacilli and Gram-positive cocci (OR>2). Olsenella uli and Lactobacillus spp. predominated over other Gram-positive rods. A possible association exists between Lactobacillus spp. and Gram-positive cocci in root canals of teeth with apical periodontitis receiving treatment.

  17. Raman Spectroscopy of Xylitol Uptake and Metabolism in Gram-Positive and Gram-Negative Bacteria▿

    Science.gov (United States)

    Palchaudhuri, Sunil; Rehse, Steven J.; Hamasha, Khozima; Syed, Talha; Kurtovic, Eldar; Kurtovic, Emir; Stenger, James

    2011-01-01

    Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy. PMID:21037297

  18. Polymers for binding of the gram-positive oral pathogen Streptococcus mutans

    Science.gov (United States)

    Magennis, Eugene P.; Francini, Nora; Mastrotto, Francesca; Catania, Rosa; Redhead, Martin; Fernandez-Trillo, Francisco; Bradshaw, David; Churchley, David; Winzer, Klaus; Alexander, Cameron

    2017-01-01

    Streptococcus mutans is the most significant pathogenic bacterium implicated in the formation of dental caries and, both directly and indirectly, has been associated with severe conditions such as multiple sclerosis, cerebrovascular and peripheral artery disease. Polymers able to selectively bind S. mutans and/or inhibit its adhesion to oral tissue in a non-lethal manner would offer possibilities for addressing pathogenicity without selecting for populations resistant against bactericidal agents. In the present work two libraries of 2-(dimethylamino)ethyl methacrylate (pDMAEMA)-based polymers were synthesized with various proportions of either N,N,N-trimethylethanaminium cationic- or sulfobetaine zwitterionic groups. These copolymers where initially tested as potential macromolecular ligands for S. mutans NCTC 10449, whilst Escherichia coli MG1655 was used as Gram-negative control bacteria. pDMAEMA-derived materials with high proportions of zwitterionic repeating units were found to be selective for S. mutans, in both isolated and S. mutans–E. coli mixed bacterial cultures. Fully sulfobetainized pDMAEMA was subsequently found to bind/cluster preferentially Gram-positive S. mutans and S. aureus compared to Gram negative E. coli and V. harveyi. A key initial stage of S. mutans pathogenesis involves a lectin-mediated adhesion to the tooth surface, thus the range of potential macromolecular ligands was further expanded by investigating two glycopolymers bearing α-mannopyranoside and β-galactopyranoside pendant units. Results with these polymers indicated that preferential binding to either S. mutans or E. coli can be obtained by modulating the glycosylation pattern of the chosen multivalent ligands without incurring unacceptable cytotoxicity in a model gastrointestinal cell line. Overall, our results allowed to identify a structure–property relationship for the potential antimicrobial polymers investigated, and suggest that preferential binding to Gram-positive S

  19. The optimization and validation of the Biotyper MALDI-TOF MS database for the identification of Gram-positive anaerobic cocci

    NARCIS (Netherlands)

    Veloo, A. C. M.; de Vries, E D; Jean-Pierre, H.; Justesen, U. S.; Morris, T.; Urban, E.; Wybo, I.; van Winkelhoff, A. J.

    OBJECTIVES: Gram-positive anaerobic cocci (GPAC) account for 24-31% of the anaerobic bacteria isolated from human clinical specimens. At present GPAC are underrepresented in the Biotyper MALDI-TOF MS database. Profiles of new species have yet to be added. We present the optimization of the MALDI-TOF

  20. Systemic resistance induced by rhizosphere bacteria

    NARCIS (Netherlands)

    Loon, L.C. van; Bakker, P.A.H.M.; Pieterse, C.M.J.

    1998-01-01

    Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Rhizobacteria-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis, bean,

  1. Cytokine profile in severe gram-positive and gram-negative abdominal sepsis

    Science.gov (United States)

    Surbatovic, Maja; Popovic, Nada; Vojvodic, Danilo; Milosevic, Ivan; Acimovic, Gordana; Stojicic, Milan; Veljovic, Milic; Jevdjic, Jasna; Djordjevic, Dragan; Radakovic, Sonja

    2015-01-01

    Sepsis is a principal cause of death in critical care units worldwide and consumes considerable healthcare resources. The aim of our study was to determine whether the early cytokine profile can discriminate between Gram-positive and Gram-negative bacteraemia (GPB and GNB, respectively) and to assess the prognostic value regarding outcome in critically ill patients with severe abdominal sepsis. The outcome measure was hospital mortality. Blood samples were obtained from 165 adult patients with confirmed severe abdominal sepsis. Levels of the proinflammatory mediators TNF-α, IL-8, IL-12 and IFN-γ and the anti-inflammatory mediators IL-1ra, IL-4, IL-10 and TGF-β1 were determined and correlated with the nature of the bacteria isolated from the blood culture and outcome. The cytokine profile in our study indicated that the TNF-α levels were 2-fold, IL-8 were 3.3-fold, IFN-γ were 13-fold, IL-1ra were 1.05-fold, IL-4 were 1.4-fold and IL-10 were 1.83-fold higher in the GNB group compared with the GPB group. The TNF-α levels were 4.7-fold, IL-8 were 4.6-fold, IL-1ra were 1.5-fold and IL-10 were 3.3-fold higher in the non-survivors compared with the survivors. PMID:26079127

  2. European surveillance study on antimicrobial susceptibility of Gram-positive anaerobic cocci

    DEFF Research Database (Denmark)

    Brazier, J; Chmelar, D; Dubreuil, L

    2008-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of microorganisms frequently isolated from local and systemic infections. In this study, the antimicrobial susceptibilities of clinical strains isolated in 10 European countries were investigated. After identification of 299 GPAC...

  3. Cystic neutrophilic granulomatous mastitis: an underappreciated pattern strongly associated with gram-positive bacilli.

    Science.gov (United States)

    Renshaw, Andrew A; Derhagopian, Robert P; Gould, Edwin W

    2011-09-01

    Although granulomatous lobular mastitis is associated with gram-positive bacilli such as Corynebacterium, this association is not well known. We report 3 cases of mastitis caused by gram-positive bacilli. All 3 abscesses were suppurative with distinct enlarged cystic spaces in which rare gram-positive bacilli were identified. Two cases were also granulomatous. Cultures in all 3 cases were negative. All 3 patients recovered after biopsy and tetracycline-based therapy. Infection in the breast by gram-positive bacilli is associated with a distinct histologic pattern, including cystic spaces in the setting of neutrophilic/granulomatous inflammation that can be recognized and should prompt careful search for the organism within enlarged vacuoles.

  4. In vitro activity of XF-73, a novel antibacterial agent, against antibiotic-sensitive and -resistant Gram-positive and Gram-negative bacterial species.

    Science.gov (United States)

    Farrell, David J; Robbins, Marion; Rhys-Williams, William; Love, William G

    2010-06-01

    The antibacterial activity of XF-73, a dicationic porphyrin drug, was investigated against a range of Gram-positive and Gram-negative bacteria with known antibiotic resistance profiles, including resistance to cell wall synthesis, protein synthesis, and DNA and RNA synthesis inhibitors as well as cell membrane-active antibiotics. Antibiotic-sensitive strains for each of the bacterial species tested were also included for comparison purposes. XF-73 was active [minimum inhibitory concentration (MIC) 0.25-4 mg/L] against all of the Gram-positive bacteria tested, irrespective of the antibiotic resistance profile of the isolates, suggesting that the mechanism of action of XF-73 is unique compared with the major antibiotic classes. Gram-negative activity was lower (MIC 1 mg/L to > 64 mg/L). Minimum bactericidal concentration data confirmed that the activity of XF-73 was bactericidal. Time-kill kinetics against healthcare-associated and community-associated meticillin-resistant Staphylococcus aureus isolates demonstrated that XF-73 was rapidly bactericidal, with > 5 log(10) kill obtained after 15 min at 2 x MIC, the earliest time point sampled. The post-antibiotic effect (PAE) for XF-73 under conditions where the PAE for vancomycin was 5.4 h. XF-73 represents a novel broad-spectrum Gram-positive antibacterial drug with potentially beneficial characteristics for the treatment and prevention of Gram-positive bacterial infections. 2010. Published by Elsevier B.V.

  5. Different Use of Cell Surface Glycosaminoglycans As Adherence Receptors to Corneal Cells by Gram Positive and Gram Negative Pathogens

    Science.gov (United States)

    García, Beatriz; Merayo-Lloves, Jesús; Rodríguez, David; Alcalde, Ignacio; García-Suárez, Olivia; Alfonso, José F.; Baamonde, Begoña; Fernández-Vega, Andrés; Vazquez, Fernando; Quirós, Luis M.

    2016-01-01

    The epithelium of the cornea is continuously exposed to pathogens, and adhesion to epithelial cells is regarded as an essential first step in bacterial pathogenesis. In this article, the involvement of glycosaminoglycans in the adhesion of various pathogenic bacteria to corneal epithelial cells is analyzed. All microorganisms use glycosaminoglycans as receptors, but arranged in different patterns depending on the Gram-type of the bacterium. The heparan sulfate chains of syndecans are the main receptors, though other molecular species also seem to be involved, particularly in Gram-negative bacteria. Adherence is inhibited differentially by peptides, including heparin binding sequences, indicating the participation of various groups of Gram-positive, and -negative adhesins. The length of the saccharides produces a major effect, and low molecular weight chains inhibit the binding of Gram-negative microorganisms but increase the adherence of Gram-positives. Pathogen adhesion appears to occur preferentially through sulfated domains, and is very dependent on N- and 6-O-sulfation of the glucosamine residue and, to a lesser extent, 2-O sulfation of uronic acid. These data show the differential use of corneal receptors, which could facilitate the development of new anti-infective strategies. PMID:27965938

  6. Tetranychus urticae mites do not mount an induced immune response against bacteria.

    Science.gov (United States)

    Santos-Matos, Gonçalo; Wybouw, Nicky; Martins, Nelson E; Zélé, Flore; Riga, Maria; Leitão, Alexandre B; Vontas, John; Grbić, Miodrag; Van Leeuwen, Thomas; Magalhães, Sara; Sucena, Élio

    2017-06-14

    The genome of the spider mite Tetranychus urticae , a herbivore, is missing important elements of the canonical Drosophila immune pathways necessary to fight bacterial infections. However, it is not known whether spider mites can mount an immune response and survive bacterial infection. In other chelicerates, bacterial infection elicits a response mediated by immune effectors leading to the survival of infected organisms. In T. urticae , infection by either Escherichia coli or Bacillus megaterium did not elicit a response as assessed through genome-wide transcriptomic analysis. In line with this, spider mites died within days even upon injection with low doses of bacteria that are non-pathogenic to Drosophila Moreover, bacterial populations grew exponentially inside the infected spider mites. By contrast, Sancassania berlesei , a litter-dwelling mite, controlled bacterial proliferation and resisted infections with both Gram-negative and Gram-positive bacteria lethal to T. urticae This differential mortality between mite species was absent when mites were infected with heat-killed bacteria. Also, we found that spider mites harbour in their gut 1000-fold less bacteria than S. berlesei We show that T. urticae has lost the capacity to mount an induced immune response against bacteria, in contrast to other mites and chelicerates but similarly to the phloem feeding aphid Acyrthosiphon pisum Hence, our results reinforce the putative evolutionary link between ecological conditions regarding exposure to bacteria and the architecture of the immune response. © 2017 The Authors.

  7. Probing interaction of Gram-positive and Gram-negative bacterial cells with ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Aanchal; Bhargava, Richa; Poddar, Pankaj, E-mail: p.poddar@ncl.res.in

    2013-04-01

    In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ∼ 64 and ∼ 256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration. Highlights: ► Effect of ZnO nanorods on the growth cycles of four bacterial strains. ► A relation has been established between growth rate of bacteria and concentration. ► Serious damage in the morphology of bacterial cells in the presence of ZnO nanorods. ► Microscopic studies to see the time dependent effect on bacterial cells.

  8. Thusin, a novel two-component lantibiotic with potent antimicrobial activity against several Gram-positive pathogens

    Directory of Open Access Journals (Sweden)

    Bingyue Xin

    2016-07-01

    Full Text Available Due to the rapidly increasing prevalence of multidrug-resistant bacterial strains, the need for new antimicrobial drugs to treat infections has become urgent. Bacteriocins, which are antimicrobial peptides of bacterial origin, are considered potential alternatives to conventional antibiotics and have attracted widespread attention in recent years. Among these bacteriocins, lantibiotics, especially two-component lantibiotics, exhibit potent antimicrobial activity against some clinically relevant Gram-positive pathogens and have potential applications in the pharmaceutical industry. In this study, we characterized a novel two-component lantibiotic termed thusin that consists of Thsα, Thsβ and Thsβ' (mutation of Thsβ, A14G and that was isolated from a B. thuringiensis strain BGSC 4BT1. Thsα and Thsβ (or Thsβ' exhibit optimal antimicrobial activity at a 1:1 ratio and act sequentially to affect target cells, and they are all highly thermostable (100°C for 30 min and pH tolerant (pH 2.0 to 9.0. Thusin shows remarkable efficacy against all tested Gram-positive bacteria and greater activities than two known lantibiotics thuricin 4A-4 and ticin A4, and one antibiotic vancomycin against various bacterial pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus (MRSA, Staphylococcus sciuri, Enterococcus faecalis, and Streptococcus pneumoniae. Moreover, thusin is also able to inhibit the outgrowth of Bacillus cereus spores. The potent antimicrobial activity of thusin against some Gram-positive pathogens indicates that it has potential for the development of new drugs.

  9. Effects of rhodomyrtone on Gram-positive bacterial tubulin homologue FtsZ

    Directory of Open Access Journals (Sweden)

    Dennapa Saeloh

    2017-02-01

    Full Text Available Rhodomyrtone, a natural antimicrobial compound, displays potent activity against many Gram-positive pathogenic bacteria, comparable to last-defence antibiotics including vancomycin and daptomycin. Our previous studies pointed towards effects of rhodomyrtone on the bacterial membrane and cell wall. In addition, a recent molecular docking study suggested that the compound could competitively bind to the main bacterial cell division protein FtsZ. In this study, we applied a computational approach (in silico, in vitro, and in vivo experiments to investigate molecular interactions of rhodomyrtone with FtsZ. Using molecular simulation, FtsZ conformational changes were observed in both (S- and (R-rhodomyrtone binding states, compared with the three natural states of FtsZ (ligand-free, GDP-, and GTP-binding states. Calculations of free binding energy showed a higher affinity of FtsZ to (S-rhodomyrtone (−35.92 ± 0.36 kcal mol−1 than the GDP substrate (−23.47 ± 0.25 kcal mol−1 while less affinity was observed in the case of (R-rhodomyrtone (−18.11 ± 0.11 kcal mol−1. In vitro experiments further revealed that rhodomyrtone reduced FtsZ polymerization by 36% and inhibited GTPase activity by up to 45%. However, the compound had no effect on FtsZ localization in Bacillus subtilis at inhibitory concentrations and cells also did not elongate after treatment. Higher concentrations of rhodomyrtone did affect localization of FtsZ and also affected localization of its membrane anchor proteins FtsA and SepF, showing that the compound did not specifically inhibit FtsZ but rather impaired multiple divisome proteins. Furthermore, a number of cells adopted a bean-like shape suggesting that rhodomyrtone possibly possesses further targets involved in cell envelope synthesis and/or maintenance.

  10. An extreme-halophile archaebacterium possesses the interlock type of prephenate dehydratase characteristic of the Gram-positive eubacteria

    Science.gov (United States)

    Jensen, R. A.; d'Amato, T. A.; Hochstein, L. I.

    1988-01-01

    The focal point of phenylalanine biosynthesis is a dehydratase reaction which in different organisms may be prephenate dehydratase, arogenate dehydratase, or cyclohexadienyl dehydratase. Gram-positive, Gram-negative, and cyanobacterial divisions of the eubacterial kingdom exhibit different dehydratase patterns. A new extreme-halophile isolate, which grows on defined medium and is tentatively designated as Halobacterium vallismortis CH-1, possesses the interlock type of prephenate dehydratase present in Gram-positive bacteria. In addition to the conventional sensitivity to feedback inhibition by L-phenylalanine, the phenomenon of metabolic interlock was exemplified by the sensitivity of prephenate dehydratase to allosteric effects produced by extra-pathway (remote) effectors. Thus, L-tryptophan inhibited activity while L-tyrosine, L-methionine, L-leucine and L-isoleucine activated the enzyme. L-Isoleucine and L-phenylalanine were effective at micromolar levels; other effectors operated at mM levels. A regulatory mutant selected for resistance to growth inhibition caused by beta-2-thienylalanine possessed an altered prephenate dehydratase in which a phenomenon of disproportionately low activity at low enzyme concentration was abolished. Inhibition by L-tryptophan was also lost, and activation by allosteric activators was diminished. Not only was sensitivity to feedback inhibition by L-phenylalanine lost, but the mutant enzyme was now activated by this amino acid (a mutation type previously observed in Bacillus subtilis). It remains to be seen whether this type of prephenate dehydratase will prove to be characteristic of all archaebacteria or of some archaebacterial subgroup cluster.

  11. The effect of nutrient media water purity on LIBS based identification of bacteria

    Science.gov (United States)

    Single pulse laser induced breakdown spectroscopy (LIBS) is used as the basis for discrimination between 3 genera of Gram-negative bacteria and 2 genera of gram-positive bacteria representing pathogenic threats commonly found in poultry processing rinse waters. Because LIBS-based discrimination reli...

  12. Organo-Selenium Coatings Inhibit Gram-Negative and Gram-Positive Bacterial Attachment to Ophthalmic Scleral Buckle Material.

    Science.gov (United States)

    Tran, Phat; Arnett, Avery; Jarvis, Courtney; Mosley, Thomas; Tran, Khien; Hanes, Rob; Webster, Dan; Mitchell, Kelly; Dominguez, Leo; Hamood, Abdul; Reid, Ted W

    2017-09-01

    Biofilm formation is a problem for solid and sponge-type scleral buckles. This can lead to complications that require removal of the buckle, and result in vision loss due to related ocular morbidity, primarily infection, or recurrent retinal detachment. We investigate the ability of a covalent organo-selenium coating to inhibit biofilm formation on a scleral buckle. Sponge and solid Labtican brand scleral buckles were coated with organo-selenium coupled to a silyation reagent. Staphylococcus aureus biofilm formation was monitored by a standard colony-forming unit assay and the confocal laser scanning microscopy, while Pseudomonas aeruginosa biofilm formation was examined by scanning electron microscopy. Stability studies were done, by soaking in phosphate buffer saline (PBS) at room temperature for 2 months. Toxicity against human corneal epithelial cell was examined by growing the cells in the presence of organo-selenium-coated scleral buckles. The organo-selenium coating inhibited biofilm formation by gram-negative and gram-positive bacteria. The buckle coatings also were shown to be fully active after soaking in PBS for 2 months. The organo-selenium coatings had no effect on the viability of human corneal epithelial cells. Organo-selenium can be used to covalently coat a scleral buckle, which is stable and inhibits biofilm formation for gram-negative and gram-positive bacteria. The organo-selenium buckle coating was stable and nontoxic to cell culture. This technology provides a means to inhibit bacterial attachment to devices attached to the eye, without damage to ocular cells.

  13. Resistance of Gram-positive bacteria to nisin is not determined by Lipid II levels

    NARCIS (Netherlands)

    Kramer, NE; Smid, EJ; Kok, J; de Kruijff, B; Kuipers, OP; Breukink, E; Kramer, Naomi E.; Smid, Eddy J.

    2004-01-01

    Lipid II is essential for nisin-mediated pore formation at nano-molar concentrations. We tested whether nisin resistance could result from different Lipid II levels, by comparing the maximal Lipid II pool in Micrococcus flavus (sensitive) and Listeria monocytogenes (relatively insensitive) and their

  14. epsilon, a New Subunit of RNA Polymerase Found in Gram-Positive Bacteria

    Czech Academy of Sciences Publication Activity Database

    Keller, A. N.; Yang, X.; Wiedermannová, Jana; Delumeau, O.; Krásný, Libor; Lewis, P. J.

    2014-01-01

    Roč. 196, č. 20 (2014), s. 3622-3632 ISSN 0021-9193 R&D Projects: GA ČR(CZ) GBP305/12/G034 Institutional support: RVO:61388971 Keywords : RNA polymerase * subunit * X-ray crystallography Subject RIV: EE - Microbiology, Virology Impact factor: 2.808, year: 2014

  15. Functional analysis of circular and linear bacteriocins of Gram-positive bacteria

    NARCIS (Netherlands)

    Kemperman, Robèr Antoine

    2005-01-01

    SUMMARY & GENERAL DISCUSSION Preservation methods such as drying and fermenting to store food products for longer periods of time have been used for centuries. Nowadays, people desire fresh and minimally processed food, to be prepared with minimal cooking. This sets new targets for the food

  16. Genetic features of circular bacteriocins produced by Gram-positive bacteria

    NARCIS (Netherlands)

    Maqueda, Mercedes; Sánchez-Hidalgo, Marina; Fernández, Matilde; Montalbán-López, Manuel; Valdivia, Eva; Martínez-Bueno, Manuel

    This review highlights the main genetic features of circular bacteriocins, which require the co-ordinated expression of several genetic determinants. In general terms, it has been demonstrated that the expression of such structural genes must be combined with the activity of proteins involved in

  17. Host range of enterococcal vanA plasmids among Gram-positive intestinal bacteria

    DEFF Research Database (Denmark)

    Werner, Guido; Freitas, Ana R.; Coque, Teresa M.

    2010-01-01

    recipients. Transfer rates were calculated per donor and recipient. Transconjugants were confirmed by determining their phenotypic and genotypic properties. Stability of plasmids in the new host was assessed in long-term growth experiments. RESULTS: In total, 282 enterococcal matings and 73 inter...

  18. Flavins mediate extracellular electron transfer in Gram-positive Bacillus megaterium strain LLD-1

    DEFF Research Database (Denmark)

    You, Le-Xing; Liu, Li-Dan; Xiao, Yong

    2018-01-01

    The extracellular electron transfer (EET) mechanism of an isolated Gram-positive Bacillus megaterium strain (LLD-1), identified by 16S rRNA gene sequencing and physiological analysis, was investigated in the present study. The electrochemical activity of strain LLD-1 was confirmed by electrochemi...

  19. Identification of aerobic Gram-positive bacilli by use of Vitek MS.

    Science.gov (United States)

    Navas, Maria; Pincus, David H; Wilkey, Kathy; Sercia, Linda; LaSalvia, Margaret; Wilson, Deborah; Procop, Gary W; Richter, Sandra S

    2014-04-01

    The accuracy of Vitek MS mass spectrometric identifications was assessed for 206 clinically significant isolates of aerobic Gram-positive bacilli representing 20 genera and 38 species. The Vitek MS identifications were correct for 85% of the isolates (56.3% to the species level, 28.6% limited to the genus level), with misidentifications occurring for 7.3% of the isolates.

  20. Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Lee, Mi Hee; Park, Bong Joo; Jin, Soo Chang; Kim, Dohyun; Kim, Jungsung; Park, Jong-Chul; Han, Inho; Hyun, Soon O; Chung, Kie-Hyung

    2009-01-01

    Microbial biofilms are a functional matrix of microbial cells, enveloped in polysaccharides, enzymes and virulence factors secreted by them that can develop on indwelling medical devices and biomaterials. Plasma sterilization has been widely studied in recent years for biological applications. In this study, we evaluated the possibility of removal and anti-recovery of biofilms by microwave-induced argon plasma at atmospheric pressure. We observed that all bacterial biofilms formatted by Gram-negative and Gram-positive bacteria are removed in less than 20 s, and the growth inhibitions of planktonic bacteria within biofilms are also confirmed by plasma exposure for 5 s. These results suggest that our plasma system can be applied to medical and biological fields where the removal of biofilms and their debris is required.

  1. Regulatory RNAs in Bacillus subtilis: a Gram-Positive Perspective on Bacterial RNA-Mediated Regulation of Gene Expression

    Science.gov (United States)

    Mars, Ruben A. T.; Nicolas, Pierre; Denham, Emma L.

    2016-01-01

    SUMMARY Bacteria can employ widely diverse RNA molecules to regulate their gene expression. Such molecules include trans-acting small regulatory RNAs, antisense RNAs, and a variety of transcriptional attenuation mechanisms in the 5′ untranslated region. Thus far, most regulatory RNA research has focused on Gram-negative bacteria, such as Escherichia coli and Salmonella. Hence, there is uncertainty about whether the resulting insights can be extrapolated directly to other bacteria, such as the Gram-positive soil bacterium Bacillus subtilis. A recent study identified 1,583 putative regulatory RNAs in B. subtilis, whose expression was assessed across 104 conditions. Here, we review the current understanding of RNA-based regulation in B. subtilis, and we categorize the newly identified putative regulatory RNAs on the basis of their conservation in other bacilli and the stability of their predicted secondary structures. Our present evaluation of the publicly available data indicates that RNA-mediated gene regulation in B. subtilis mostly involves elements at the 5′ ends of mRNA molecules. These can include 5′ secondary structure elements and metabolite-, tRNA-, or protein-binding sites. Importantly, sense-independent segments are identified as the most conserved and structured potential regulatory RNAs in B. subtilis. Altogether, the present survey provides many leads for the identification of new regulatory RNA functions in B. subtilis. PMID:27784798

  2. Regulatory RNAs in Bacillus subtilis: a Gram-Positive Perspective on Bacterial RNA-Mediated Regulation of Gene Expression.

    Science.gov (United States)

    Mars, Ruben A T; Nicolas, Pierre; Denham, Emma L; van Dijl, Jan Maarten

    2016-12-01

    Bacteria can employ widely diverse RNA molecules to regulate their gene expression. Such molecules include trans-acting small regulatory RNAs, antisense RNAs, and a variety of transcriptional attenuation mechanisms in the 5' untranslated region. Thus far, most regulatory RNA research has focused on Gram-negative bacteria, such as Escherichia coli and Salmonella. Hence, there is uncertainty about whether the resulting insights can be extrapolated directly to other bacteria, such as the Gram-positive soil bacterium Bacillus subtilis. A recent study identified 1,583 putative regulatory RNAs in B. subtilis, whose expression was assessed across 104 conditions. Here, we review the current understanding of RNA-based regulation in B. subtilis, and we categorize the newly identified putative regulatory RNAs on the basis of their conservation in other bacilli and the stability of their predicted secondary structures. Our present evaluation of the publicly available data indicates that RNA-mediated gene regulation in B. subtilis mostly involves elements at the 5' ends of mRNA molecules. These can include 5' secondary structure elements and metabolite-, tRNA-, or protein-binding sites. Importantly, sense-independent segments are identified as the most conserved and structured potential regulatory RNAs in B. subtilis. Altogether, the present survey provides many leads for the identification of new regulatory RNA functions in B. subtilis. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  3. Recovery of vancomycin-resistant gram-positive cocci from children.

    OpenAIRE

    Green, M; Wadowsky, R M; Barbadora, K

    1990-01-01

    A cross-sectional survey of vancomycin-resistant gram-positive cocci (VRGPC) in the feces of children was initiated after several bacteremic infections with these organisms occurred at our hospital. A selective medium consisting of colistin-nalidixic acid agar, 5% sheep blood, vancomycin (5 mg/liter), and amphotericin B (8 mg/liter) was developed to isolate VRGPC. A single stool specimen submitted to the clinical microbiology laboratory from each of 48 patients was inoculated onto the medium....

  4. Fermentation of glycolate by a pure culture of a strictly anaerobic gram-positive bacterium belonging to the family Lachnospiraceae.

    Science.gov (United States)

    Janssen, Peter H; Hugenholtz, Philip

    2003-05-01

    The component bacteria of a three-membered mixed culture able to ferment glycolate to acetate, propionate and CO(2) were isolated in pure culture. All three strains were strict anaerobes that, on the basis of comparative 16S rRNA gene sequence analysis, belonged to the order Clostridiales in the phylum Firmicutes (low G+C gram-positive bacteria). Two of the strains were not involved in glycolate metabolism. The third, the glycolate-fermenting strain 19gly4 (DSM 11261), was related to members of the family Lachnospiraceae. The cells of strain 19gly4 were oval- to lemon-shaped, 0.85 microm long and 0.65 microm in diameter, occurring singly, in pairs, or in chains of up to 30 cells. Strain 19gly4 fermented glycolate or fumarate to acetate, succinate, and CO(2). Hydrogen was not formed, and strain 19gly4 was able to grow on glycolate in pure culture without any syntrophic hydrogen transfer and without the use of an external electron acceptor. There was no evidence for homoacetogenic metabolism. This bacterium therefore differs in metabolism from previously reported glycolate-utilising anaerobes.

  5. Lactic Acid Bacteria Inducing a Weak Interleukin-12 and Tumor Necrosis Alpha Response in Human Dendritic Cells Inhibit Strongly Stimulating Lactic Acid Bacteria but Act Synergistically with Gram-Negative Bacteria

    DEFF Research Database (Denmark)

    Zeuthen, Louise Hjerrild; Christensen, Hanne Risager; Frøkiær, Hanne

    2006-01-01

    The development and maintenance of immune homeostasis indispensably depend on signals from the gut flora. Lactic acid bacteria (LAB), which are gram-positive (G+) organisms, are plausible significant players and have received much attention. Gram-negative (G-) commensals, such as members...

  6. Treatment of gram-positive deep sternal wound infections in cardiac surgery -experiences with daptomycin-

    Directory of Open Access Journals (Sweden)

    Coskun Kasim O

    2011-09-01

    Full Text Available Abstract The reported incidence of deep sternal wound infection (DSWI after cardiac surgery is 0.4-5% with Staphylococcus aureus being the most common pathogen isolated from infected wound sternotomies and bacteraemic blood cultures. This infection is associated with a higher morbidity and mortality than other known aetiologies. Little is reported about the optimal antibiotic management. The aim of the study is to quantify the application of daptomycin treatment of DSWI due to gram-positive organisms post cardiac surgery. We performed an observational analysis in 23 cases of post sternotomy DSWI with gram-positive organisms February 2009 and September 2010. When the wound appeared viable and the microbiological cultures were negative, the technique of chest closure was individualised to the patient. The incidence of DSWI was 1.46%. The mean dose of daptomycin application was 4.4 ± 0.9 mg/kg/d and the average duration of the daptomycin application was 14.47 ± 7.33 days. In 89% of the patients VAC therapy was used. The duration from daptomycin application to sternal closure was 18 ± 13.9 days. The parameters of infection including, fibrinogen (p = 0.03, white blood cell count (p = 0.001 and C-reactive protein (p = 0.0001 were significantly reduced after daptomycin application. We had no mortality and wound healing was successfully achieved in all patients. Treatment of DSWI due to gram-positive organisms with a daptomycin-containing antibiotic regimen is safe, effective and promotes immediate improvement of local wound conditions. Based on these observations, daptomycin may offer a new treatment option for expediting surgical management of DSWI after cardiac surgery.

  7. Prognostic factors and monomicrobial necrotizing fasciitis: gram-positive versus gram-negative pathogens

    Directory of Open Access Journals (Sweden)

    Hsu Wei-Hsiu

    2011-01-01

    Full Text Available Abstract Background Monomicrobial necrotizing fasciitis is rapidly progressive and life-threatening. This study was undertaken to ascertain whether the clinical presentation and outcome for patients with this disease differ for those infected with a gram-positive as compared to gram-negative pathogen. Methods Forty-six patients with monomicrobial necrotizing fasciitis were examined retrospectively from November 2002 to January 2008. All patients received adequate broad-spectrum antibiotic therapy, aggressive resuscitation, prompt radical debridement and adjuvant hyperbaric oxygen therapy. Eleven patients were infected with a gram-positive pathogen (Group 1 and 35 patients with a gram-negative pathogen (Group 2. Results Group 2 was characterized by a higher incidence of hemorrhagic bullae and septic shock, higher APACHE II scores at 24 h post-admission, a higher rate of thrombocytopenia, and a higher prevalence of chronic liver dysfunction. Gouty arthritis was more prevalent in Group 1. For non-survivors, the incidences of chronic liver dysfunction, chronic renal failure and thrombocytopenia were higher in comparison with those for survivors. Lower level of serum albumin was also demonstrated in the non-survivors as compared to those in survivors. Conclusions Pre-existing chronic liver dysfunction, chronic renal failure, thrombocytopenia and hypoalbuminemia, and post-operative dependence on mechanical ventilation represent poor prognostic factors in monomicrobial necrotizing fasciitis. Patients with gram-negative monobacterial necrotizing fasciitis present with more fulminant sepsis.

  8. Identification of Multiple Soluble Fe(III Reductases in Gram-Positive Thermophilic Bacterium Thermoanaerobacter indiensis BSB-33

    Directory of Open Access Journals (Sweden)

    Subrata Pal

    2014-01-01

    Full Text Available Thermoanaerobacter indiensis BSB-33 has been earlier shown to reduce Fe(III and Cr(VI anaerobically at 60°C optimally. Further, the Gram-positive thermophilic bacterium contains Cr(VI reduction activity in both the membrane and cytoplasm. The soluble fraction prepared from T. indiensis cells grown at 60°C was found to contain the majority of Fe(III reduction activity of the microorganism and produced four distinct bands in nondenaturing Fe(III reductase activity gel. Proteins from each of these bands were partially purified by chromatography and identified by mass spectrometry (MS with the help of T. indiensis proteome sequences. Two paralogous dihydrolipoamide dehydrogenases (LPDs, thioredoxin reductase (Trx, NADP(H-nitrite reductase (Ntr, and thioredoxin disulfide reductase (Tdr were determined to be responsible for Fe(III reductase activity. Amino acid sequence and three-dimensional (3D structural similarity analyses of the T. indiensis Fe(III reductases were carried out with Cr(VI reducing proteins from other bacteria. The two LPDs and Tdr showed very significant sequence and structural identity, respectively, with Cr(VI reducing dihydrolipoamide dehydrogenase from Thermus scotoductus and thioredoxin disulfide reductase from Desulfovibrio desulfuricans. It appears that in addition to their iron reducing activity T. indiensis LPDs and Tdr are possibly involved in Cr(VI reduction as well.

  9. Endocarditis associated with cardiac catheterization due to a Gram-positive coccus designated Micrococcus mucilaginosus incertae sedis.

    Science.gov (United States)

    Rubin, S J; Lyons, R W; Murcia, A J

    1978-01-01

    A gram-positive coccus, presently named Micrococcus mucilaginosus incertae sedis, was isolated from 14 blood cultures from a patient with endocarditis. The first positive blood culture was drawn 5 days after the patient underwent cardiac catheterization. PMID:670378

  10. The optimization and validation of the Biotyper MALDI-TOF MS database for the identification of Gram-positive anaerobic cocci

    DEFF Research Database (Denmark)

    Veloo, A C M; de Vries, E D; Jean-Pierre, H

    2016-01-01

    Gram-positive anaerobic cocci (GPAC) account for 24%-31% of the anaerobic bacteria isolated from human clinical specimens. At present, GPAC are under-represented in the Biotyper MALDI-TOF MS database. Profiles of new species have yet to be added. We present the optimization of the matrix-assisted......Gram-positive anaerobic cocci (GPAC) account for 24%-31% of the anaerobic bacteria isolated from human clinical specimens. At present, GPAC are under-represented in the Biotyper MALDI-TOF MS database. Profiles of new species have yet to be added. We present the optimization of the matrix......-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) database for the identification of GPAC. Main spectral profiles (MSPs) were created for 108 clinical GPAC isolates. Identity was confirmed using 16S rRNA gene sequencing. Species identification was considered to be reliable...... if the sequence similarity with its closest relative was ≥98.7%. The optimized database was validated using 140 clinical isolates. The 16S rRNA sequencing identity was compared with the MALDI-TOF MS result. MSPs were added from 17 species that were not yet represented in the MALDI-TOF MS database or were under...

  11. Brazilian experience in EU-CORE: daptomycin registry and treatment of serious Gram-positive infections

    Directory of Open Access Journals (Sweden)

    Artur Timerman

    Full Text Available OBJECTIVES: To collect data about non-controlled prescribing use of daptomycin and its impact among Brazilian patients with serious Gram positive bacterial infection, as well as the efficacy and safety outcomes. MATERIALS AND METHODS: This is a multi-center, retrospective, non-interventional registry (August 01, 2009 to June 30, 2011 to collect data on 120 patients (44 patients in the first year and 76 patients in the second year who had received at least one dose of commercial daptomycin in Brazil for the treatment of serious Gram-positive bacterial infection. RESULTS: Right-sided endocarditis (15.8%, complicated skin and soft tissue infections (cSSTIwound (15.0% and bacteremia-catheter-related (14.2% were the most frequent primary infections; lung (21.7% was the most common site for infection. Daptomycin was used empirically in 76 (63.3% patients, and methicillin-resistant Staphylococcus aureus (MRSA was the most common suspected pathogen (86.1%. 82.5% of the cultures were obtained prior to or shortly after initiation of daptomycin therapy. Staphylococcus spp. - coagulase negative, MRSA, and methicillin-susceptible S. aureus were the most frequently identified pathogens (23.8%, 23.8% and 12.5%, respectively. The most common daptomycin dose administered for bacteremia and cSSTI was 6 mg/kg (30.6% and 4 mg/kg (51.7%, respectively. The median duration of inpatient daptomycin therapy was 14 days. Most patients (57.1% did not receive daptomycin while in intensive care unit. Carbapenem (22.5% was the most commonly used antibiotic concomitantly. The patients showed clinical improvement after two days (median following the start of daptomycin therapy. The clinical success rate was 80.8% and the overall rate of treatment failure was 10.8%. The main reasons for daptomycin discontinuation were successful end of therapy (75.8%, switched therapy (11.7%, and treatment failure (4.2%. Daptomycin demonstrated a favorable safety and tolerability profile

  12. Environmental gram-positive mastitis treatment: in vitro sensitivity and bacteriologic cure.

    Science.gov (United States)

    Cattell, M B; Dinsmore, R P; Belschner, A P; Carmen, J; Goodell, G

    2001-09-01

    A clinical trial was conducted in a large dairy herd to determine the efficacy of intramammary pirlimycin hydrochloride administration during lactation for bacteriologic clearance of gram-positive environmental clinical and subclinical mastitis infections. Quarters infected with environmental streptococci that received pirlimycin therapy (13/28) were 1.8 times more likely to resolve infection than untreated quarters (5/14). The small numbers of quarters infected with coagulase-negative staphylococci resulted in inadequate power to assess treatment differences in cure rate. Although the association was not statistically significant, quarters from cows with sensitive environmental streptococci isolates from composite samples (8/13) resolved infection with treatment at approximately twice the rate of treated quarters with resistant isolates (3/10).

  13. Subcellular localization for Gram positive and Gram negative bacterial proteins using linear interpolation smoothing model.

    Science.gov (United States)

    Saini, Harsh; Raicar, Gaurav; Dehzangi, Abdollah; Lal, Sunil; Sharma, Alok

    2015-12-07

    Protein subcellular localization is an important topic in proteomics since it is related to a protein׳s overall function, helps in the understanding of metabolic pathways, and in drug design and discovery. In this paper, a basic approximation technique from natural language processing called the linear interpolation smoothing model is applied for predicting protein subcellular localizations. The proposed approach extracts features from syntactical information in protein sequences to build probabilistic profiles using dependency models, which are used in linear interpolation to determine how likely is a sequence to belong to a particular subcellular location. This technique builds a statistical model based on maximum likelihood. It is able to deal effectively with high dimensionality that hinders other traditional classifiers such as Support Vector Machines or k-Nearest Neighbours without sacrificing performance. This approach has been evaluated by predicting subcellular localizations of Gram positive and Gram negative bacterial proteins. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Extracellular communication in bacteria

    DEFF Research Database (Denmark)

    Chhabra, S.R.; Philipp, B.; Eberl, L.

    2005-01-01

    molecules, in different Gram-positive and Gram-negative bacteria they control pathogenicity, secondary metabolite production, biofilm differentiation, DNA transfer and bioluminescence. The development of biosensors for the detection of these signal molecules has greatly facilitated their subsequent chemical...

  15. Relative roles of the cellular and humoral responses in the Drosophila host defense against three gram-positive bacterial infections.

    Directory of Open Access Journals (Sweden)

    Nadine T Nehme

    2011-03-01

    Full Text Available Two NF-kappaB signaling pathways, Toll and immune deficiency (imd, are required for survival to bacterial infections in Drosophila. In response to septic injury, these pathways mediate rapid transcriptional activation of distinct sets of effector molecules, including antimicrobial peptides, which are important components of a humoral defense response. However, it is less clear to what extent macrophage-like hemocytes contribute to host defense.In order to dissect the relative importance of humoral and cellular defenses after septic injury with three different gram-positive bacteria (Micrococcus luteus, Enterococcus faecalis, Staphylococcus aureus, we used latex bead pre-injection to ablate macrophage function in flies wildtype or mutant for various Toll and imd pathway components. We found that in all three infection models a compromised phagocytic system impaired fly survival--independently of concomitant Toll or imd pathway activation. Our data failed to confirm a role of the PGRP-SA and GNBP1 Pattern Recognition Receptors for phagocytosis of S. aureus. The Drosophila scavenger receptor Eater mediates the phagocytosis by hemocytes or S2 cells of E. faecalis and S. aureus, but not of M. luteus. In the case of M. luteus and E. faecalis, but not S. aureus, decreased survival due to defective phagocytosis could be compensated for by genetically enhancing the humoral immune response.Our results underscore the fundamental importance of both cellular and humoral mechanisms in Drosophila immunity and shed light on the balance between these two arms of host defense depending on the invading pathogen.

  16. Laser-induced fluorescence imaging of bacteria

    Science.gov (United States)

    Hilton, Peter J.

    1998-12-01

    This paper outlines a method for optically detecting bacteria on various backgrounds, such as meat, by imaging their laser induced auto-fluorescence response. This method can potentially operate in real-time, which is many times faster than current bacterial detection methods, which require culturing of bacterial samples. This paper describes the imaging technique employed whereby a laser spot is scanned across an object while capturing, filtering, and digitizing the returned light. Preliminary results of the bacterial auto-fluorescence are reported and plans for future research are discussed. The results to date are encouraging with six of the eight bacterial strains investigated exhibiting auto-fluorescence when excited at 488 nm. Discrimination of these bacterial strains against red meat is shown and techniques for reducing background fluorescence discussed.

  17. Complete genome sequence of Paenibacillus riograndensis SBR5(T), a Gram-positive diazotrophic rhizobacterium.

    Science.gov (United States)

    Brito, Luciana Fernandes; Bach, Evelise; Kalinowski, Jörn; Rückert, Christian; Wibberg, Daniel; Passaglia, Luciane M; Wendisch, Volker F

    2015-08-10

    Paenibacillus riograndensis is a Gram-positive rhizobacterium which exhibits plant growth promoting activities. It was isolated from the rhizosphere of wheat grown in the state of Rio Grande do Sul, Brazil. Here we announce the complete genome sequence of P. riograndensis strain SBR5(T). The genome of P. riograndensis SBR5(T) consists of a circular chromosome of 7,893,056bps. The genome was finished and fully annotated, containing 6705 protein coding genes, 87 tRNAs and 27 rRNAs. The knowledge of the complete genome helped to explain why P. riograndensis SBR5(T) can grow with the carbon sources arabinose and mannitol, but not myo-inositol, and to explain physiological features such as biotin auxotrophy and antibiotic resistances. The genome sequence will be valuable for functional genomics and ecological studies as well as for application of P. riograndensis SBR5(T) as plant growth-promoting rhizobacterium. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Computational design and characterization of a temperature-sensitive plasmid replicon for gram positive thermophiles

    Directory of Open Access Journals (Sweden)

    Olson Daniel G

    2012-05-01

    Full Text Available Abstract Background Temperature-sensitive (Ts plasmids are useful tools for genetic engineering, but there are currently none compatible with the gram positive, thermophilic, obligate anaerobe, Clostridium thermocellum. Traditional mutagenesis techniques yield Ts mutants at a low frequency, and therefore requires the development of high-throughput screening protocols, which are also not available for this organism. Recently there has been progress in the development of computer algorithms which can predict Ts mutations. Most plasmids currently used for genetic modification of C. thermocellum are based on the replicon of plasmid pNW33N, which replicates using the RepB replication protein. To address this problem, we set out to create a Ts plasmid by mutating the gene coding for the RepB replication protein using an algorithm designed by Varadarajan et al. (1996 for predicting Ts mutants based on the amino-acid sequence of the protein. Results A library of 34 mutant plasmids was designed, synthesized and screened, resulting in 6 mutants which exhibited a Ts phenotype. Of these 6, the one with the most temperature-sensitive phenotype (M166A was compared with the original plasmid. It exhibited lower stability at 48°C and was completely unable to replicate at 55°C. Conclusions The plasmid described in this work could be useful in future efforts to genetically engineer C. thermocellum, and the method used to generate this plasmid may be useful for others trying to make Ts plasmids.

  19. Recovery of vancomycin-resistant gram-positive cocci from children.

    Science.gov (United States)

    Green, M; Wadowsky, R M; Barbadora, K

    1990-03-01

    A cross-sectional survey of vancomycin-resistant gram-positive cocci (VRGPC) in the feces of children was initiated after several bacteremic infections with these organisms occurred at our hospital. A selective medium consisting of colistin-nalidixic acid agar, 5% sheep blood, vancomycin (5 mg/liter), and amphotericin B (8 mg/liter) was developed to isolate VRGPC. A single stool specimen submitted to the clinical microbiology laboratory from each of 48 patients was inoculated onto the medium. Plates were incubated at 35 degrees C with 5% carbon dioxide and examined at 24, 48, and 72 h. Susceptibilities were determined by broth microdilution. A total of 14 isolates from 11 of 48 (22%) children were recovered. The density of growth ranged from a single colony to 2+. The VRGPC were identified as Leuconostoc lactis (n = 2), Lactobacillus confusus (n = 4), Enterococcus species (n = 5), and Lactococcus lactis (n = 3). One strain of Lactobacillus confusus was recovered from both the stool and the blood of one of these patients. The MICs of vancomycin were 4 micrograms/ml for one of the isolates, 8 micrograms/ml for four of the isolates, and more than 16 micrograms/ml for the remaining eight isolates. All isolates were susceptible to both penicillin and ampicillin. Only 1 of the 11 children had received prior treatment with vancomycin. We conclude that low concentrations of VRGPC may be common in the gastrointestinal tracts of children.

  20. Optimization of linezolid treatment regimens for Gram-positive bacterial infections based on pharmacokinetic/pharmacodynamic analysis.

    Science.gov (United States)

    Yang, Minjie; Zhang, Jing; Chen, Yuancheng; Liang, Xiaoyu; Guo, Yan; Yu, Jicheng; Zhu, Demei; Zhang, Yingyuan

    2017-01-01

    To optimize linezolid treatment regimens for Gram-positive bacterial infections based on pharmacokinetic/pharmacodynamic analysis. The minimum inhibitory concentration (MIC) distribution of 572 Gram-positive strains from patients with clinically confirmed infections was analyzed. Using the Monte Carlo simulation method, the cumulative fraction of response and probability of target attainment were determined for linezolid regimens of 600 mg q.12h and q.8h Results: Linezolid dosage of 600 mg q.12h yielded >90% cumulative fraction of response and probability of target attainment for staphylococcal infections with an MIC of ≤1 mg/l, enterococcal infections with higher MIC values required 600 mg q.8h. Linezolid 600 mg q.12h is still the clinically recommended empirical dosage for Gram-positive bacterial infections. However, as bacterial MICs increase, 600 mg q.8h may be required to achieve better efficacy.

  1. Effect of sample preparation on the discrimination of bacterial isolates cultured in liquid nutrient media using laser induced breakdown spectroscopy

    Science.gov (United States)

    Laser induced breakdown spectroscopy (LIBS) is used as the basis for discrimination between 2 genera of gram-negative bacteria and 2 genera of gram-positive bacteria representing pathogenic threats commonly found in poultry processing rinse waters. Because LIBS-based discrimination relies primarily ...

  2. Rational approaches to the therapy of nosocomial infections caused by gram-positive microorganisms in cancer p

    Directory of Open Access Journals (Sweden)

    V. V. Aginova

    2017-01-01

    Full Text Available Nosocomial infections caused by gram-positive organisms, including Staphylococcus aureus and enterococci (Enterococcus faecium and Enterococcus faecalis are steadily increasing in almost all clinics around the world. Cancer patients have a higher risk of hospital-acquired infections than non-cancer patients. Cancer patients are immunosuppressed due to increased use of broad-spectrum antibiotics and chemotherapy drugs, radiation therapy, surgery and use of steroids. This paper presents an analysis of resistance of gram-positive bacterial pathogens to antimicrobial agents to determine treatment strategy for cancer patients.

  3. Effectiveness of aqueous and hydroalcoholic extracts of Acanthospermum australe (Loefl. Kuntze against diarrhea-inducing bacteria

    Directory of Open Access Journals (Sweden)

    R. Mallmann

    2018-01-01

    Full Text Available Abstract Leaves and roots of Acanthospermum australe (Asteraceae have been used in Brazilian folk medicine for the treatment of various ailments including diarrhea, skin diseases, blennorrhagia, dyspepsia, parasitic worms and malaria. The aim of study was to characterize the chemical profiles of the aqueous and hydroalcoholic extracts of leaves and roots of A. australe, and to evaluate their antimicrobial activities against diarrhea-inducing bacteria (Enterococcus faecalis, Shigella dysenteriae and Yersinia enterocolitica, as well as their cytotoxic properties. Aqueous leaf extracts were obtained by infusion, while aqueous root extracts were obtained by decoction. The hydroalcoholic leaf and root extracts were prepared by maceration in 90% ethanol for 3 days. Antimicrobial activity was assessed using standard techniques and cytotoxicity was evaluated using Chinese hamster ovary cells CHO-K1. Chemical analysis revealed the presence of tannins, flavonoids, saponins and phenolic compounds in the extracts. Although root extracts were not effective against E. faecalis, leaf extracts at concentrations of 20 mg/mL exhibited bactericidal activities against this microorganism. The hydroalcoholic root extract was unique in presenting a bactericidal effect against S. dysenteriae. None of the extracts showed bacteriostatic or bactericidal activities against Y. enterocolitica. The results presented herein demonstrate that the Gram-positive E. faecalis and the Gram-negative S. dysenteriae were susceptible to A. australe extracts, although bacteriostatic/bactericidal activities were only observed at concentrations considered too high for clinical application. Our results support the ethnopharmacological use of A. australe in the treatment of gastrointestinal disorders, particularly diarrhea caused by infectious bacteria, although further studies are required to determine the anti-diarrhea effects and the toxicities of the extracts in vivo.

  4. Amino acids in cell wall of Gram-positive bacterium Micrococcus sp. hsn08 with flocculation activity on Chlorella vulgaris biomass.

    Science.gov (United States)

    Li, Yi; Xu, Yanting; Zheng, Tianling; Wang, Hailei

    2018-02-01

    The aim of this work was to investigate the flocculation mechanism by Gram-positive bacterium, Micrococcus sp. hsn08 as a means for harvesting Chlorella vulgaris biomass. Bacterial cells of Micrococcus sp. hsn08 were added into algal culture to harvest algal cells through direct contacting with algae to form flocs. Viability dependence test confirmed that flocculation activity does not depend on live bacteria, but on part of the peptidoglycan. The further investigation has determined that amino acids in cell wall play an important role to flocculate algal cells. Positively charged calcium can combine bacterial and algal cells together, and form a bridge between them, thereby forming the flocs, suggesting that ions bridging is the main flocculation mechanism. These results suggest that bacterial cells of Micrococcus sp. hsn08 can be applied to harvest microalgae biomass with the help of amino acids in cell wall. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Lipoproteins/peptides are sepsis-inducing toxins from bacteria that can be neutralized by synthetic anti-endotoxin peptides.

    Science.gov (United States)

    Martinez de Tejada, Guillermo; Heinbockel, Lena; Ferrer-Espada, Raquel; Heine, Holger; Alexander, Christian; Bárcena-Varela, Sergio; Goldmann, Torsten; Correa, Wilmar; Wiesmüller, Karl-Heinz; Gisch, Nicolas; Sánchez-Gómez, Susana; Fukuoka, Satoshi; Schürholz, Tobias; Gutsmann, Thomas; Brandenburg, Klaus

    2015-09-22

    Sepsis, a life-threatening syndrome with increasing incidence worldwide, is triggered by an overwhelming inflammation induced by microbial toxins released into the bloodstream during infection. A well-known sepsis-inducing factor is the membrane constituent of Gram-negative bacteria, lipopolysaccharide (LPS), signalling via Toll-like receptor-4. Although sepsis is caused in more than 50% cases by Gram-positive and mycoplasma cells, the causative compounds are still poorly described. In contradicting investigations lipoproteins/-peptides (LP), lipoteichoic acids (LTA), and peptidoglycans (PGN), were made responsible for eliciting this pathology. Here, we used human mononuclear cells from healthy donors to determine the cytokine-inducing activity of various LPs from different bacterial origin, synthetic and natural, and compared their activity with that of natural LTA and PGN. We demonstrate that LP are the most potent non-LPS pro-inflammatory toxins of the bacterial cell walls, signalling via Toll-like receptor-2, not only in vitro, but also when inoculated into mice: A synthetic LP caused sepsis-related pathological symptoms in a dose-response manner. Additionally, these mice produced pro-inflammatory cytokines characteristic of a septic reaction. Importantly, the recently designed polypeptide Aspidasept(®) which has been proven to efficiently neutralize LPS in vivo, inhibited cytokines induced by the various non-LPS compounds protecting animals from the pro-inflammatory activity of synthetic LP.

  6. The Causes of Post-Operative Meningitis: The Comparison Of Gram-Negative and Gram-Positive Pathogens.

    Science.gov (United States)

    Kurtaran, Behice; Kuscu, Ferit; Ulu, Aslihan; Inal, Ayse Seza; Komur, Suheyla; Kibar, Filiz; Cetinalp, Nuri Eralp; Ozsoy, Kerem Mazhar; Arslan, Yusuf Kemal; Aksu, Hasan Salih; Tasova, Yesim

    2017-06-20

    In this study, we aim to determine the microbiological etiology in critically ill neurosurgical patients with nosocomial meningitis (NM) and show the impact of Gram-negative rods and differences of patient's characteristics, clinical and prognostic measures between Gram-negative and Gram-positive meningitis. In this prospective, one center study we reviewed all adult patients hospitalized during a 12-year period and identified pathogens isolated from post-neurosurgical cases of NM. Demographic, clinical, and treatment characteristics were noted from the medical records. Of the 134 bacterial NM patients, 78 were male and 56 were female, with a mean age of 46±15.9 and median age of 50 (18-80) years. 141 strains isolated; 82 (58.2%) were Gram negative, 59 (41.8%) were Gram positive. Most common isolated microorganism was Acinetobacter baumannii (%34.8). In comparison of mortality data shows that the patients who have meningitis with Gram-negative pathogens have higher mortality than with Gram positives (p=0.034). The duration between surgery and meningitis was shorter in Gram negative meningitis cases compared to others (p=0.045) but the duration between the diagnosis and death was shorter in Gram-positive meningitis cases compared to Gram negatives (p= 0.017). CSF protein and lactate level were higher and glucose level was lower in cases of NM with Gram negatives (p value were respectively, 0.022, 0.039 and 0.049). As conclusions; in NM, Gram-negative pathogens were seen more frequently; A.baumanni was the predominant pathogen; and NM caused by Gram negatives had worse clinical and laboratory characteristic and prognostic outcome than Gram positives.

  7. hydroxyalkanoate (PHAs) producing bacteria isolated

    African Journals Online (AJOL)

    SERVER

    2007-07-04

    Jul 4, 2007 ... ium (MSM), having inhibitors for Gram positive bacteria and fungi and a mixed ... Two techniques were used for detecting the presence of polymer: staining ... was saline solution at 600 nm wavelength on VARIAN DSM 100.

  8. Infective Endocarditis: Identification of Catalase-Negative, Gram-Positive Cocci from Blood Cultures by Partial 16S rRNA Gene Analysis and by Vitek 2 Examination.

    Science.gov (United States)

    Abdul-Redha, Rawaa Jalil; Kemp, Michael; Bangsborg, Jette M; Arpi, Magnus; Christensen, Jens Jørgen

    2010-01-01

    Streptococci, enterococci and Streptococcus-like bacteria are frequent etiologic agents of infective endocarditis and correct species identification can be a laboratory challenge. Viridans streptococci (VS) not seldomly cause contamination of blood cultures. Vitek 2 and partial sequencing of the 16S rRNA gene were applied in order to compare the results of both methods. STRAINS ORIGINATED FROM TWO GROUPS OF PATIENTS: 149 strains from patients with infective endocarditis and 181 strains assessed as blood culture contaminants. Of the 330 strains, based on partial 16S rRNA gene sequencing results, 251 (76%) were VS strains, 10 (3%) were pyogenic streptococcal strains, 54 (16%) were E. faecalis strains and 15 (5%) strains belonged to a group of miscellaneous catalase-negative, Gram-positive cocci. Among VS strains, respectively, 220 (87,6%) and 31 (12,3%) obtained agreeing and non-agreeing identifications with the two methods with respect to allocation to the same VS group. Non-agreeing species identification mostly occurred among strains in the contaminant group, while for endocarditis strains notably fewer disagreeing results were observed.Only 67 of 150 strains in the mitis group strains obtained identical species identifications by the two methods. Most VS strains belonging to the groups of salivarius, anginosus, and mutans obtained agreeing species identifications with the two methods, while this only was the case for 13 of the 21 bovis strains. Pyogenic strains (n=10), Enterococcus faecalis strains (n=54) and a miscellaneous group of catalase-negative, Gram-positive cocci (n=15) seemed well identified by both methods, except that disagreements in identifications in the miscellaneous group of strains occurred for 6 of 15 strains.

  9. Sensitivity of bacteria to diamond nanoparticles of various size differs in gram-positive and gram-negative cells

    Czech Academy of Sciences Publication Activity Database

    Beranová, Jana; Seydlová, Gabriela; Kozak, Halyna; Benada, Oldřich; Fišer, R.; Artemenko, Anna; Konopásek, I.; Kromka, Alexander

    2014-01-01

    Roč. 351, č. 2 (2014), s. 179-186 ISSN 0378-1097 R&D Projects: GA ČR GAP108/12/0910; GA ČR GPP205/12/P331 Institutional support: RVO:68378271 ; RVO:61388971 Keywords : diamond nanoparticles * antibacterial properties * Escherichia coli * Bacillus subtilis * DLS * XPS Subject RIV: BO - Biophysics Impact factor: 2.121, year: 2014

  10. Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria.

    Science.gov (United States)

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

    2012-06-21

    Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg = 0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a = b = 9.435 Å, c = 6.876 Å for xAg = 0.05, a = b = 9.443 Å, c = 6.875 Å for xAg = 0.2, and a = b = 9.445 Å, c = 6.877 Å for xAg = 0.3 are in good agreement with the standard of a = b = 9.418 Å, c = 6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii).

  11. Synthesis, characterization and antibacterial activity against Gram positive and Gram negative bacteria of biomimetically coated silver nanoparticles.

    Science.gov (United States)

    Amato, Elvio; Diaz-Fernandez, Yuri A; Taglietti, Angelo; Pallavicini, Piersandro; Pasotti, Luca; Cucca, Lucia; Milanese, Chiara; Grisoli, Pietro; Dacarro, Cesare; Fernandez-Hechavarria, Jose M; Necchi, Vittorio

    2011-08-02

    In the present work, we describe a simple procedure to produce biomimetically coated silver nanoparticles (Ag NPs), based on the postfunctionalization and purification of colloidal silver stabilized by citrate. Two biological capping agents have been used (cysteine Cys and glutathione GSH). The composition of the capped colloids has been ascertained by different techniques and antibacterial tests on GSH-capped Ag NPs have been conducted under physiological conditions, obtaining values of Minimum Inhibitory Concentration (MIC) of 180 and 15 μg/mL for Staphylococcus aureus and Escherichia coli, respectively. The antibacterial activity of these GSH capped NPs can be ascribed to the direct action of metallic silver NPs, rather than to the bulk release of Ag(+).

  12. Isolation and purification of enterocin E-760 with broad antimicrobial activity against gram-positive and gram-negative bacteria.

    Science.gov (United States)

    Line, J E; Svetoch, E A; Eruslanov, B V; Perelygin, V V; Mitsevich, E V; Mitsevich, I P; Levchuk, V P; Svetoch, O E; Seal, B S; Siragusa, G R; Stern, N J

    2008-03-01

    Strain NRRL B-30745, isolated from chicken ceca and identified as Enterococcus durans, Enterococcus faecium, or Enterococcus hirae, was initially identified as antagonistic to Campylobacter jejuni. The isolate produced a 5,362-Da bacteriocin (enterocin) that inhibits the growth of Salmonella enterica serovar Enteritidis, S. enterica serovar Choleraesuis, S. enterica serovar Typhimurium, S. enterica serovar Gallinarum, Escherichia coli O157:H7, Yersinia enterocolitica, Citrobacter freundii, Klebsiella pneumoniae, Shigella dysenteriae, Pseudomonas aeruginosa, Proteus mirabilis, Morganella morganii, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Campylobacter jejuni, and 20 other Campylobacter species isolates. The enterocin, E-760, was isolated and purified by cation-exchange and hydrophobic-interaction chromatographies. The proteinaceous nature of purified enterocin E-760 was demonstrated upon treatment with various proteolytic enzymes. Specifically, the antimicrobial peptide was found to be sensitive to beta-chymotrypsin, proteinase K, and papain, while it was resistant to lysozyme and lipase. The enterocin demonstrated thermostability by retaining activity after 5 min at 100 degrees C and was stable at pH values between 5.0 and 8.7. However, activity was lost below pH 3.0 and above pH 9.5. Administration of enterocin E-760-treated feed significantly (P Enterocin E-760 also significantly (P < 0.05) reduced the colonization of naturally acquired Campylobacter species in market age broiler chickens when administered in treated feed 4 days prior to analysis.

  13. Antibacterial Activity of Extracellular Protease Isolated From an Algicolous Fungus Xylaria psidii KT30 Against Gram-Positive Bacteria

    OpenAIRE

    Indarmawan, Taufik; Mustopa, Apon Zaenal; Budiarto, Bugi Ratno; Tarman, Kustiariyah

    2016-01-01

    Infectious diseases became more serious problem for public health in recent years. Although existing antibacterial drugs have been relatively effective, they do not rule out the emergence of resistance to the drug. Therefore, the intensive exploration of new bioactive compounds from natural, especially peptide compounds began in recent decades in order-handling infection. This study aimed to isolate, purify and test the potential application of Xylaria psidii KT30 extracellular protease as an...

  14. Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria

    Science.gov (United States)

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

    2012-06-01

    Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10- x Ag x (PO4)6(OH)2, x Ag = 0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a = b = 9.435 Å, c = 6.876 Å for x Ag = 0.05, a = b = 9.443 Å, c = 6.875 Å for x Ag = 0.2, and a = b = 9.445 Å, c = 6.877 Å for x Ag = 0.3 are in good agreement with the standard of a = b = 9.418 Å, c = 6.884 Å (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples ( x Ag = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of x Ag in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth ( P. stuartii).

  15. In vitro activities of dalbavancin and nine comparator agents against anaerobic gram-positive species and corynebacteria.

    Science.gov (United States)

    Goldstein, Ellie J C; Citron, Diane M; Merriam, C Vreni; Warren, Yumi; Tyrrell, Kerin; Fernandez, Helen T

    2003-06-01

    Dalbavancin is a novel semisynthetic glycopeptide with enhanced activity against gram-positive species. Its comparative in vitro activities and those of nine comparator agents, including daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin, against 290 recent gram-positive clinical isolates strains, as determined by the NCCLS agar dilution method, were studied. The MICs of dalbavancin at which 90% of various isolates tested were inhibited were as follows: Actinomyces spp., 0.5 microg/ml; Clostridium clostridioforme, 8 microg/ml; C. difficile, 0.25 microg/ml; C. innocuum, 0.25 microg/ml; C. perfringens, 0.125 microg/ml; C. ramosum, 1 microg/ml; Eubacterium spp., 1 microg/ml; Lactobacillus spp., >32 microg/ml, Propionibacterium spp., 0.5 microg/ml; and Peptostreptococcus spp., 0.25 microg/ml. Dalbavancin was 1 to 3 dilutions more active than vancomycin against most strains. Dalbavancin exhibited excellent activity against gram-positive strains tested and warrants clinical evaluation.

  16. CcpA-dependent carbon catabolite repression in bacteria

    NARCIS (Netherlands)

    Warner, JB; Lolkema, JS; Warner, Jessica B.

    2003-01-01

    Carbon catabolite repression (CCR) by transcriptional regulators follows different mechanisms in gram-positive and gram-negative bacteria. In gram-positive bacteria, CcpA-dependent CCR is mediated by phosphorylation of the phosphoenolpyruvate:sugar phosphotransferase system intermediate HPr at a

  17. Type-IVC Secretion System: A Novel Subclass of Type IV Secretion System (T4SS) Common Existing in Gram-Positive Genus Streptococcus

    Science.gov (United States)

    Chen, Chen; Gao, George F.

    2012-01-01

    A growing number of pathogens are being found to possess specialized secretion systems which they use in various ways to subvert host defenses. Type IV secretion system (T4SS) is one of versatile secretion systems essential for the virulence and even survival of some bacteria species, and they enable the secretion of protein and DNA substrates across the cell envelope. T4SS was once believed to be present only in Gram-negative bacteria. In this study, we present evidence of a new subclass of T4SS, Type-IVC secretion system and indicate its common existence in the Gram-positive bacterial genus Streptococcus. We further identified that VirB1, VirB4, VirB6 and VirD4 are the minimal key components of this system. Using genome comparisons and evolutionary relationship analysis, we proposed that Type-IVC secretion system is movable via transposon factors and mediates the conjugative transfer of DNA, enhances bacterial pathogenicity, and could cause large-scale outbreaks of infections in humans. PMID:23056296

  18. Design, Synthesis and Evaluation of Branched RRWQWR-Based Peptides as Antibacterial Agents Against Clinically Relevant Gram-Positive and Gram-Negative Pathogens

    Directory of Open Access Journals (Sweden)

    Sandra C. Vega

    2018-03-01

    Full Text Available Multidrug resistance of pathogenic bacteria has become a public health crisis that requires the urgent design of new antibacterial drugs such as antimicrobial peptides (AMPs. Seeking to obtain new, lactoferricin B (LfcinB-based synthetic peptides as viable early-stage candidates for future development as AMPs against clinically relevant bacteria, we designed, synthesized and screened three new cationic peptides derived from bovine LfcinB. These peptides contain at least one RRWQWR motif and differ by the copy number (monomeric, dimeric or tetrameric and structure (linear or branched of this motif. They comprise a linear palindromic peptide (RWQWRWQWR, a dimeric peptide (RRWQWR2KAhx and a tetrameric peptide (RRWQWR4K2Ahx2C2. They were screened for antibacterial activity against Enterococcus faecalis (ATCC 29212 and ATCC 51575 strains, Pseudomonas aeruginosa (ATCC 10145 and ATCC 27853 strains and clinical isolates of two Gram-positive bacteria (Enterococcus faecium and Staphylococcus aureus and two Gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa. All three peptides exhibited greater activity than did the reference peptide, LfcinB (17–31, which contains a single linear RRWQWR motif. Against the ATCC reference strains, the three new peptides exhibited minimum inhibitory concentration (MIC50 values of 3.1–198.0 μM and minimum bactericidal concentration (MBC values of 25–200 μM, and against the clinical isolates, MIC50 values of 1.6–75.0 μM and MBC values of 12.5–100 μM. However, the tetrameric peptide was also found to be strongly hemolytic (49.1% at 100 μM. Scanning Electron Microscopy (SEM demonstrated that in the dimeric and tetrameric peptides, the RRWQWR motif is exposed to the pathogen surface. Our results may inform the design of new, RRWQWR-based AMPs.

  19. Differential staining of bacteria: acid fast stain.

    Science.gov (United States)

    Reynolds, Jackie; Moyes, Rita B; Breakwell, Donald P

    2009-11-01

    Acid-fastness is an uncommon characteristic shared by the genera Mycobacterium (Section 10A) and Nocardia. Because of this feature, this stain is extremely helpful in identification of these bacteria. Although Gram positive, acid-fast bacteria do not take the crystal violet into the wall well, appearing very light purple rather than the deep purple of normal Gram-positive bacteria. (c) 2009 by John Wiley & Sons, Inc.

  20. Exposure to Anacardiaceae volatile oils and their constituents induces lipid peroxidation within food-borne bacteria cells.

    Science.gov (United States)

    Montanari, Ricardo M; Barbosa, Luiz C A; Demuner, Antonio J; Silva, Cleber J; Andrade, Nelio J; Ismail, Fyaz M D; Barbosa, Maria C A

    2012-08-14

    The chemical composition of the volatile oils from five Anacardiaceae species and their activities against Gram positive and negative bacteria were assessed. The peroxidative damage within bacterial cell membranes was determined through the breakdown product malondialdehyde (MDA). The major constituents in Anacardium humile leaves oil were (E)-caryophyllene (31.0%) and α-pinene (22.0%), and in Anacardium occidentale oil they were (E)-caryophyllene (15.4%) and germacrene-D (11.5%). Volatile oil from Astronium fraxinifolium leaves were dominated by (E)-β-ocimene (44.1%) and α-terpinolene (15.2%), whilst the oil from Myracrodruon urundeuva contained an abundance of δ-3-carene (78.8%). However, Schinus terebinthifolius leaves oil collected in March and July presented different chemical compositions. The oils from all species, except the one from A. occidentale, exhibited varying levels of antibacterial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli. Oil extracted in July from S. terebinthifolius was more active against all bacterial strains than the corresponding oil extracted in March. The high antibacterial activity of the M. urundeuva oil could be ascribed to its high δ-3-carene content. The amounts of MDA generated within bacterial cells indicate that the volatile oils induce lipid peroxidation. The results suggest that one putative mechanism of antibacterial action of these volatile oils is pro-oxidant damage within bacterial cell membrane explaining in part their preservative properties.

  1. Osteopontin adsorption to Gram-positive cells reduces adhesion forces and attachment to surfaces under flow

    DEFF Research Database (Denmark)

    Kristensen, M F; Zeng, G; Neu, T R

    2017-01-01

    caries or medical device-related infections. It further investigated if OPN's effect on adhesion is caused by blocking the accessibility of glycoconjugates on bacterial surfaces. Bacterial adhesion was determined in a shear-controlled flow cell system in the presence of different concentrations of OPN......The bovine milk protein osteopontin (OPN) may be an efficient means to prevent bacterial adhesion to dental tissues and control biofilm formation. This study sought to determine to what extent OPN impacts adhesion forces and surface attachment of different bacterial strains involved in dental......, and interaction forces of single bacteria were quantified using single-cell force spectroscopy before and after OPN exposure. Moreover, the study investigated OPN's effect on the accessibility of cell surface glycoconjugates through fluorescence lectin-binding analysis. OPN strongly affected bacterial adhesion...

  2. Experience With Rapid Microarray-Based Diagnostic Technology and Antimicrobial Stewardship for Patients With Gram-Positive Bacteremia.

    Science.gov (United States)

    Neuner, Elizabeth A; Pallotta, Andrea M; Lam, Simon W; Stowe, David; Gordon, Steven M; Procop, Gary W; Richter, Sandra S

    2016-11-01

    OBJECTIVE To describe the impact of rapid diagnostic microarray technology and antimicrobial stewardship for patients with Gram-positive blood cultures. DESIGN Retrospective pre-intervention/post-intervention study. SETTING A 1,200-bed academic medical center. PATIENTS Inpatients with blood cultures positive for Staphylococcus aureus, Enterococcus faecalis, E. faecium, Streptococcus pneumoniae, S. pyogenes, S. agalactiae, S. anginosus, Streptococcus spp., and Listeria monocytogenes during the 6 months before and after implementation of Verigene Gram-positive blood culture microarray (BC-GP) with an antimicrobial stewardship intervention. METHODS Before the intervention, no rapid diagnostic technology was used or antimicrobial stewardship intervention was undertaken, except for the use of peptide nucleic acid fluorescent in situ hybridization and MRSA agar to identify staphylococcal isolates. After the intervention, all Gram-positive blood cultures underwent BC-GP microarray and the antimicrobial stewardship intervention consisting of real-time notification and pharmacist review. RESULTS In total, 513 patients with bacteremia were included in this study: 280 patients with S. aureus, 150 patients with enterococci, 82 patients with stretococci, and 1 patient with L. monocytogenes. The number of antimicrobial switches was similar in the pre-BC-GP (52%; 155 of 300) and post-BC-GP (50%; 107 of 213) periods. The time to antimicrobial switch was significantly shorter in the post-BC-GP group than in the pre-BC-GP group: 48±41 hours versus 75±46 hours, respectively (P<.001). The most common antimicrobial switch was de-escalation and time to de-escalation, was significantly shorter in the post-BC-GP group than in the pre-BC-GP group: 53±41 hours versus 82±48 hours, respectively (P<.001). There was no difference in mortality or hospital length of stay as a result of the intervention. CONCLUSIONS The combination of a rapid microarray diagnostic test with an antimicrobial

  3. Characterization of an Hfq dependent antisense sRNA in the Gram-positive human pathogen Listeria monocytogenes

    DEFF Research Database (Denmark)

    Nielsen, Jesper Sejrup; Lei Kristensen, Lisbeth; Hanghøj Chrisitansen, Mie

    between sRNA and target mRNA rely on the RNA chaperone Hfq. Hfq is a ubiquitous protein found in almost all genres of bacterial life. However, so far its role as an RNA chaperone has only been described in Gram-negative species such as Escherichia coli and Salmonella (Vogel, J. 2009). We previously...... identified several Hfq-binding sRNAs in the Gram-positive human pathogen L. monocytogenes (Christiansen et al 2006). Through bioinformatics, we have identified a number of candidate targets for one of these sRNAs (LhrA). Here, we present the characterization of one of these targets. Our results suggest...

  4. Use of MALDI-TOF Mass Spectrometry for the Fast Identification of Gram-Positive Fish Pathogens

    Science.gov (United States)

    Assis, Gabriella B. N.; Pereira, Felipe L.; Zegarra, Alexandra U.; Tavares, Guilherme C.; Leal, Carlos A.; Figueiredo, Henrique C. P.

    2017-01-01

    Gram-positive cocci, such as Streptococcus agalactiae, Lactococcus garvieae, Streptococcus iniae, and Streptococcus dysgalactiae subsp. dysgalactiae, are found throughout the world, particularly in outbreaks in farmed fish, and are thus associated with high economic losses, especially in the cultivation of Nile Tilapia. The aim of this study was to evaluate the efficacy of matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF) mass spectrometry (MS) as an alternative for the diagnosis of these pathogens. One hundred and thirty-one isolates from Brazilian outbreaks assisted by the national authority were identified using a MALDI Biotyper from Bruker Daltonics. The results showed an agreement with respect to identification (Kappa = 1) between this technique and 16S ribosomal RNA gene sequencing for S. agalactiae and L. garvieae. However, for S. iniae and S. dysgalactiae subsp. dysgalactiae, perfect agreement was only achieved after the creation of a custom main spectra profile, as well as further comparisons with 16S ribosomal RNA and multilocus sequence analysis. MALDI-TOF MS was shown to be an efficient technology for the identification of these Gram-positive pathogens, yielding a quick and precise diagnosis. PMID:28848512

  5. Neither Single nor a Combination of Routine Laboratory Parameters can Discriminate between Gram-positive and Gram-negative Bacteremia

    Science.gov (United States)

    Ratzinger, Franz; Dedeyan, Michel; Rammerstorfer, Matthias; Perkmann, Thomas; Burgmann, Heinz; Makristathis, Athanasios; Dorffner, Georg; Loetsch, Felix; Blacky, Alexander; Ramharter, Michael

    2015-01-01

    Adequate early empiric antibiotic therapy is pivotal for the outcome of patients with bloodstream infections. In clinical practice the use of surrogate laboratory parameters is frequently proposed to predict underlying bacterial pathogens; however there is no clear evidence for this assumption. In this study, we investigated the discriminatory capacity of predictive models consisting of routinely available laboratory parameters to predict the presence of Gram-positive or Gram-negative bacteremia. Major machine learning algorithms were screened for their capacity to maximize the area under the receiver operating characteristic curve (ROC-AUC) for discriminating between Gram-positive and Gram-negative cases. Data from 23,765 patients with clinically suspected bacteremia were screened and 1,180 bacteremic patients were included in the study. A relative predominance of Gram-negative bacteremia (54.0%), which was more pronounced in females (59.1%), was observed. The final model achieved 0.675 ROC-AUC resulting in 44.57% sensitivity and 79.75% specificity. Various parameters presented a significant difference between both genders. In gender-specific models, the discriminatory potency was slightly improved. The results of this study do not support the use of surrogate laboratory parameters for predicting classes of causative pathogens. In this patient cohort, gender-specific differences in various laboratory parameters were observed, indicating differences in the host response between genders. PMID:26522966

  6. Two investigational glycylcyclines, DMG-DMDOT and DMG-MINO. Antimicrobial activity studies against gram-positive species.

    Science.gov (United States)

    Johnson, D M; Jones, R N

    1996-01-01

    DMG-DMDOT (CL-331,002 OR CL-331,928) and DMG-MINO (CL-329,998 or CL-344,677) are two new semisynthetic tetracyclines called glycylcyclines, with a broad spectrum of activity and includes Enterobacteriaceae, Gram-positive cocci, JK diphtheroids, and Bacillus cereus. Potent activity was demonstrated against all Streptococcus spp. strains [minimum inhibitory concentrations] (MIC90S) 0.06-0.25 micrograms/ml) and staphylococci (oxacillin susceptible ans resistant; MIC90S 0.12-2 micrograms/ml). Both glycylcyclines (MIC90, 0.06 micrograms/ml) were more potent than minocycline (MIC90 8 micrograms/ml) against Enterococcus faecium, many of which were vancomycin resistant (116 strains). Organisms with minocycline MICs at > or = 8 micrograms/ml (Staphylococcus aureus, enterococci, beta-hemolytic streptococci, and pneumococci) had glycylcycline MIC results ranging from 0.06 to 0.5 micrograms/ml (e.g., apparent use against existing tetracycline-resistance phenotypes). Drugs in this class appear promising for therapy of infections caused by Gram-positive species now testing resistant to contemporary antimicrobial agents, and further development of compounds in this class is encouraged.

  7. Rapid Assessment of Resistance to Antibiotic Inhibitors of Protein Synthesis in the Gram-Positive Pathogens, Enterococcus faecalis and Streptococcus pneumoniae, Based on Evaluation of the Lytic Response.

    Science.gov (United States)

    Otero, Fátima; Tamayo, María; Santiso, Rebeca; Gosálvez, Jaime; Bou, Germán; Fernández, José Luis

    2017-04-01

    A novel assay for rapid determination of resistance to antibiotic inhibitors of protein synthesis was developed for the gram-positive pathogens, Enterococcus faecalis and Streptococcus pneumoniae. To this purpose, a lytic response was obtained by a brief incubation with lysozyme or a mixture of lysozyme, Triton X-100, and EDTA for E. faecalis (n = 82) and S. pneumoniae (n = 51), respectively. Lysis was quantified by visualizing the released nucleoids. Antibiotic-susceptible bacteria treated with Clinical and Laboratory Standards Institute (CLSI) breakpoint doses of erythromycin, azithromycin, or doxycycline that inhibited protein synthesis demonstrated a large reduction of lysed cells with respect to the control, that is, without antibiotics. However, cell lysis prevention was much lower in nonsusceptible strains, with unsuccessful inhibition of protein synthesis. ROC analysis showed that a reduction value of ≥35.6% and ≥40.4% discriminates susceptible and nonsusceptible strains for erythromycin and for doxycycline, respectively, in E. faecalis, whereas ≥20.0% is adequate for both macrolides and doxycycline in S. pneumoniae. Resistant stains were identified in 90-120 min with sensitivity and specificity between 91.7% and 100%. This is a proof of concept that evaluation of the lytic response may be a rapid and efficient test for determination of resistance to antibiotic inhibitors of protein synthesis.

  8. A novel insect defensin mediates the inducible antibacterial activity in larvae of the dragonfly Aeschna cyanea (Paleoptera, Odonata)

    NARCIS (Netherlands)

    Bulet, P.; Cociancich, S.; Reuland, M.; Sauber, F.; Bischoff, Rainer; Hegy, G.; Van Dorsselaer, A.; Hetru, C.; Hoffmann, J.A.

    1992-01-01

    The injection of low doses of bacteria into the aquatic larvae of dragonflies (Aeschna cyanea, Odonata, Paleoptera) induces the appearance in their hemolymph of a potent antibacterial activity. We have isolated a 38-residue peptide from this hemolymph which is strongly active against Gram-positive

  9. Commensal Bacteria-Induced Inflammasome Activation in Mouse and Human Macrophages Is Dependent on Potassium Efflux but Does Not Require Phagocytosis or Bacterial Viability.

    Directory of Open Access Journals (Sweden)

    Kejie Chen

    Full Text Available Gut commensal bacteria contribute to the pathogenesis of inflammatory bowel disease, in part by activating the inflammasome and inducing secretion of interleukin-1ß (IL-1ß. Although much has been learned about inflammasome activation by bacterial pathogens, little is known about how commensals carry out this process. Accordingly, we investigated the mechanism of inflammasome activation by representative commensal bacteria, the Gram-positive Bifidobacterium longum subspecies infantis and the Gram-negative Bacteroides fragilis. B. infantis and B. fragilis induced IL-1ß secretion by primary mouse bone marrow-derived macrophages after overnight incubation. IL-1ß secretion also occurred in response to heat-killed bacteria and was only partly reduced when phagocytosis was inhibited with cytochalasin D. Similar results were obtained with a wild-type immortalized mouse macrophage cell line but neither B. infantis nor B. fragilis induced IL-1ß secretion in a mouse macrophage line lacking the nucleotide-binding/leucine-rich repeat pyrin domain containing 3 (NLRP3 inflammasome. IL-1ß secretion in response to B. infantis and B. fragilis was significantly reduced when the wild-type macrophage line was treated with inhibitors of potassium efflux, either increased extracellular potassium concentrations or the channel blocker ruthenium red. Both live and heat-killed B. infantis and B. fragilis also induced IL-1ß secretion by human macrophages (differentiated THP-1 cells or primary monocyte-derived macrophages after 4 hours of infection, and the secretion was inhibited by raised extracellular potassium and ruthenium red but not by cytochalasin D. Taken together, our findings indicate that the commensal bacteria B. infantis and B. fragilis activate the NLRP3 inflammasome in both mouse and human macrophages by a mechanism that involves potassium efflux and that does not require bacterial viability or phagocytosis.

  10. Cyclic Di-GMP Binding by an Assembly ATPase (PilB2) and Control of Type IV Pilin Polymerization in the Gram-Positive Pathogen Clostridium perfringens.

    Science.gov (United States)

    Hendrick, William A; Orr, Mona W; Murray, Samantha R; Lee, Vincent T; Melville, Stephen B

    2017-05-15

    polymerizing the pilin, PilA2, into a pilus. The assembly ATPase PilB2 and its cognate membrane protein partner, PilC2, were purified. PilB2 bound the intracellular signal molecule c-di-GMP. Increased levels of intracellular c-di-GMP led to increased polymerization of PilA2, indicating that Gram-positive bacteria use this molecule to regulate pilus synthesis. These findings provide valuable information for understanding how pathogenic clostridia regulate TFP to cause human diseases. Copyright © 2017 American Society for Microbiology.

  11. Comparative activity of ceftobiprole against Gram-positive and Gram-negative isolates from Europe and the Middle East: the CLASS study.

    Science.gov (United States)

    Rossolini, Gian M; Dryden, Matthew S; Kozlov, Roman S; Quintana, Alvaro; Flamm, Robert K; Läuffer, Jörg M; Lee, Emma; Morrissey, Ian; CLASS Study Group

    2011-01-01

    to assess the in vitro activity of ceftobiprole and comparators against a recent collection of Gram-positive and Gram-negative pathogens, in order to detect potential changes in susceptibility patterns, and to evaluate the Etest assay for ceftobiprole susceptibility testing. contemporary Gram-positive and Gram-negative isolates (excluding extended-spectrum β-lactamase-producing isolates) from across Europe and the Middle East were collected, and their susceptibility to ceftobiprole, vancomycin, teicoplanin, linezolid, ceftazidime and cefepime was assessed using the Etest method. Quality testing [using Etest and broth microdilution (BMD)] was conducted at a central reference laboratory. some 5041 Gram-positive and 4026 Gram-negative isolates were included. Against Gram-positive isolates overall, ceftobiprole had the lowest MIC50 (0.5 mg/L), compared with 1 mg/L for its comparators (vancomycin, teicoplanin and linezolid). Against methicillin-resistant Staphylococcus aureus, all four agents had a similar MIC90 (2 mg/L), but ceftobiprole had a 4-fold better MIC90 (0.5 mg/L) against methicillin-susceptible strains. Only 38 Gram-positive isolates were confirmed as ceftobiprole resistant. Among Gram-negative strains, 86.9%, 91.7% and 95.2% were susceptible to ceftobiprole, ceftazidime and cefepime, respectively. Pseudomonas aeruginosa was less susceptible to all three antimicrobials than any other Gram-negative pathogen. There was generally good agreement between local Etest results and those obtained at the reference laboratory (for ceftobiprole: 86.8% with Gram-negatives; and 94.7% with Gram-positives), as well as between results obtained by BMD and Etest methods (for ceftobiprole: 98.2% with Gram-negatives; and 98.4% with Gram-positives). ceftobiprole exhibits in vitro activity against a wide range of Gram-positive and Gram-negative pathogens, including multidrug-resistant strains. No changes in its known susceptibility profile were identified.

  12. Inducible xylitol dehydrogenases in enteric bacteria.

    OpenAIRE

    Doten, R C; Mortlock, R P

    1985-01-01

    Morganella morganii ATCC 25829, Providencia stuartii ATCC 25827, Serratia marcescens ATCC 13880, and Erwinia sp. strain 4D2P were found to induce a xylitol dehydrogenase when grown on a xylitol-containing medium. The xylitol dehydrogenases were partially purified from the four strains, and those from M. morganii ATCC 25829, P. stuartii ATCC 25827, and S. marcescens ATCC 13880 were all found to oxidize xylitol to D-xylulose. These three enzymes had KmS for xylitol of 7.1 to 16.4 mM and molecul...

  13. Effect of extremely low frequency electromagnetic fields on growth rate and morphology of bacteria.

    Science.gov (United States)

    Inhan-Garip, Ayse; Aksu, Burak; Akan, Zafer; Akakin, Dilek; Ozaydin, A Nilufer; San, Tangul

    2011-12-01

    To determine the effect of extremely low frequency (bacteria and to determine any morphological changes that might have been caused by ELF-EMF. Six bacterial strains, three Gram-negative and three Gram-positive were subjected to 50 Hz, 0.5 mT ELF-EMF for 6 h. To determine growth rate after ELF-EMF application, bacteria exposed to ELF-EMF for 3 h were collected, transferred to fresh medium and cultured without field application for another 4 h. Growth-rate was determined by optical density (OD) measurements made every hour. Morphological changes were determined with Transmission electron microscopy (TEM) for two gram-negative and two gram-positive strains collected after 3 h of field application. A decrease in growth rate with respect to control samples was observed for all strains during ELF-EMF application. The decrease in growth-rate continued when exposed bacteria were cultured without field application. Significant ultrastructural changes were observed in all bacterial strains, which were seen to resemble the alterations caused by cationic peptides. This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria.

  14. In vitro characterization of the antivirulence target of Gram-positive pathogens, peptidoglycan O-acetyltransferase A (OatA.

    Directory of Open Access Journals (Sweden)

    David Sychantha

    2017-10-01

    Full Text Available The O-acetylation of the essential cell wall polymer peptidoglycan occurs in most Gram-positive bacterial pathogens, including species of Staphylococcus, Streptococcus and Enterococcus. This modification to peptidoglycan protects these pathogens from the lytic action of the lysozymes of innate immunity systems and, as such, is recognized as a virulence factor. The key enzyme involved, peptidoglycan O-acetyltransferase A (OatA represents a particular challenge to biochemical study since it is a membrane associated protein whose substrate is the insoluble peptidoglycan cell wall polymer. OatA is predicted to be bimodular, being comprised of an N-terminal integral membrane domain linked to a C-terminal extracytoplasmic domain. We present herein the first biochemical and kinetic characterization of the C-terminal catalytic domain of OatA from two important human pathogens, Staphylococcus aureus and Streptococcus pneumoniae. Using both pseudosubstrates and novel biosynthetically-prepared peptidoglycan polymers, we characterized distinct substrate specificities for the two enzymes. In addition, the high resolution crystal structure of the C-terminal domain reveals an SGNH/GDSL-like hydrolase fold with a catalytic triad of amino acids but with a non-canonical oxyanion hole structure. Site-specific replacements confirmed the identity of the catalytic and oxyanion hole residues. A model is presented for the O-acetylation of peptidoglycan whereby the translocation of acetyl groups from a cytoplasmic source across the cytoplasmic membrane is catalyzed by the N-terminal domain of OatA for their transfer to peptidoglycan by its C-terminal domain. This study on the structure-function relationship of OatA provides a molecular and mechanistic understanding of this bacterial resistance mechanism opening the prospect for novel chemotherapeutic exploration to enhance innate immunity protection against Gram-positive pathogens.

  15. Outcomes of single organism peritonitis in peritoneal dialysis: gram negatives versus gram positives in the Network 9 Peritonitis Study.

    Science.gov (United States)

    Bunke, C M; Brier, M E; Golper, T A

    1997-08-01

    The use of the "peritonitis rate" in the management of patients undergoing peritoneal dialysis is assuming importance in comparing the prowess of facilities, care givers and new innovations. For this to be a meaningful outcome measure, the type of infection (causative pathogen) must have less clinical significance than the number of infections during a time interval. The natural history of Staphylococcus aureus, pseudomonas, and fungal peritonitis would not support that the outcome of an episode of peritonitis is independent of the causative pathogen. Could this concern be extended to other more frequently occurring pathogens? To address this, the Network 9 Peritonitis Study identified 530 episodes of single organism peritonitis caused by a gram positive organism and 136 episodes caused by a single non-pseudomonal gram negative (NPGN) pathogen. Coincidental soft tissue infections (exit site or tunnel) occurred equally in both groups. Outcomes of peritonitis were analyzed by organism classification and by presence or absence of a soft tissue infection. NPGN peritonitis was associated with significantly more frequent catheter loss, hospitalization, and technique failure and was less likely to resolve regardless of the presence or absence of a soft tissue infection. Hospitalization and death tended to occur more frequently with enterococcal peritonitis than with other gram positive peritonitis. The outcomes in the NPGN peritonitis group were significantly worse (resolution, catheter loss, hospitalization, technique failure) compared to coagulase negative staphylococcal or S. aureus peritonitis, regardless of the presence or absence of a coincidental soft tissue infection. Furthermore, for the first time, the poor outcomes of gram negative peritonitis are shown to be independent of pseudomonas or polymicrobial involvement or soft tissue infections. The gram negative organism appears to be the important factor. In addition, the outcome of peritonitis caused by S. aureus

  16. Copper Nanoparticle Induced Cytotoxicity to Nitrifying Bacteria ...

    Science.gov (United States)

    With the inclusion of engineered nanomaterials in industrial processes and consumer products, wastewater treatments plants (WWTPs) will serve as a major sink for these emerging contaminants. Previous research has demonstrated that nanomaterials are potentially toxic to microbial communities utilized in biological wastewater treatment (BWT). Copper-based nanoparticles (CuNPs) are of particular interest based on their increasing use in wood treatment, paints, household products, coatings, and byproducts of semiconductor manufacturing. A critical step in BWT is nutrient removal via denitrification. This study examined the potential toxicity of bare and polyvinylpyrrolidone (PVP) coated CuO, and Cu2O nanoparticles, as well as Cu ions to microbial communities responsible for nitrogen removal in BWT. Inhibition was inferred from changes to the specific oxygen uptake rate (sOUR) in the absence and presence of Cu ions and CuNPs. X-ray absorption fine structure spectroscopy, with Linear Combination Fitting (LCF), was utilized to track changes to Cu speciation throughout exposure. Results indicate that the dissolution of Cu ions from CuNPs drive microbial inhibition. The presence of a PVP coating on CuNPs has little effect on inhibition. LCF fitting of the biomass combined with metal partitioning analysis supports the current hypothesis that Cu-induced cytotoxicity is primarily caused by reactive oxygen species formed from ionic Cu in solution via catalytic reaction inter

  17. Vapor-induced transfer of bacteria in the absence of mechanical disturbances

    International Nuclear Information System (INIS)

    Ayoub, G.M.; Dahdah, L.; Alameddine, I.; Malaeb, L.

    2014-01-01

    Graphical abstract: - Highlights: • Study is first to investigate the possibility of transfer of bacteria through vapor. • Bacteria exhibited transfer in the absence of mechanical disturbances in reactors. • Gram positive smaller bacteria transferred more than gram negative larger bacteria. • Transfer probability increases at optimal growth temperature of mesophilic bacteria. • Salinity lowers bacterial survival and has synergistic effect with temperature. - Abstract: Transfer of bacteria through water vapor generated at moderate temperatures (30–50 °C) in passive solar stills, has scarcely been reported. The objective of this research was to investigate whether bacteria in highly humid atmospheres can get transferred through water vapor in the absence of other transfer media to find their way to the distillate. To achieve this objective, passive solar reactors were chosen as the medium for experimentation, and distillation experiments were conducted by spiking a pure bacterial culture (Escherichia coli, Klebsiella pneumonia or Enterococcus faecalis) in low mineralized water vs. highly mineralized water in the dark under moderate temperatures ranges (30–35 °C, 40–45 °C and 50–55 °C). Results showed that bacteria indeed get transferred with the vapor in stills when not exposed to solar U.V. radiation. The trends observed were adequately explained by a zero-modified Hurdle–Poisson model. The numbers of cultivable bacterial colonies transferred were bacterial size, water type and temperature dependent with highest transfers occurring in E. faecalis > E. coli > K. pneumonia at the 40 °C range in low mineralized water. Proper management strategies are recommended to achieve complete disinfection in solar stills

  18. Genomics of Probiotic Bacteria

    Science.gov (United States)

    O'Flaherty, Sarah; Goh, Yong Jun; Klaenhammer, Todd R.

    Probiotic bacteria from the Lactobacillus and Bifidobacterium species belong to the Firmicutes and the Actinobacteria phylum, respectively. Lactobacilli are members of the lactic acid bacteria (LAB) group, a broadly defined family of microorganisms that ferment various hexoses into primarily lactic acid. Lactobacilli are typically low G + C gram-positive species which are phylogenetically diverse, with over 100 species documented to date. Bifidobacteria are heterofermentative, high G + C content bacteria with about 30 species of bifidobacteria described to date.

  19. Study effect of plant extraction for Cuscuta europaea (Dodder against two species of bacteria Staphylococcus aureus and Escherichia coli

    Directory of Open Access Journals (Sweden)

    Jasim A. Abdullah

    2016-12-01

    Conclusion: There are no significant differences between the concentration of plant extract of bacteria, and we showed the plant extract have a high effect on gram positive bacteria but do not have any effect on gram negative bacteria.

  20. Probiotic Bacteria Induce a ‘Glow of Health’

    Science.gov (United States)

    Smillie, Christopher; Varian, Bernard J.; Ibrahim, Yassin M.; Lakritz, Jessica R.; Alm, Eric J.; Erdman, Susan E.

    2013-01-01

    Radiant skin and hair are universally recognized as indications of good health. However, this ‘glow of health’ display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health. PMID:23342023

  1. A Disulfide Bond-forming Machine Is Linked to the Sortase-mediated Pilus Assembly Pathway in the Gram-positive Bacterium Actinomyces oris*

    Science.gov (United States)

    Reardon-Robinson, Melissa E.; Osipiuk, Jerzy; Chang, Chungyu; Wu, Chenggang; Jooya, Neda; Joachimiak, Andrzej; Das, Asis; Ton-That, Hung

    2015-01-01

    Export of cell surface pilins in Gram-positive bacteria likely occurs by the translocation of unfolded precursor polypeptides; however, how the unfolded pilins gain their native conformation is presently unknown. Here, we present physiological studies to demonstrate that the FimA pilin of Actinomyces oris contains two disulfide bonds. Alanine substitution of cysteine residues forming the C-terminal disulfide bridge abrogates pilus assembly, in turn eliminating biofilm formation and polymicrobial interaction. Transposon mutagenesis of A. oris yielded a mutant defective in adherence to Streptococcus oralis, and revealed the essential role of a vitamin K epoxide reductase (VKOR) gene in pilus assembly. Targeted deletion of vkor results in the same defects, which are rescued by ectopic expression of VKOR, but not a mutant containing an alanine substitution in its conserved CXXC motif. Depletion of mdbA, which encodes a membrane-bound thiol-disulfide oxidoreductase, abrogates pilus assembly and alters cell morphology. Remarkably, overexpression of MdbA or a counterpart from Corynebacterium diphtheriae, rescues the Δvkor mutant. By alkylation assays, we demonstrate that VKOR is required for MdbA reoxidation. Furthermore, crystallographic studies reveal that A. oris MdbA harbors a thioredoxin-like fold with the conserved CXXC active site. Consistently, each MdbA enzyme catalyzes proper disulfide bond formation within FimA in vitro that requires the catalytic CXXC motif. Because the majority of signal peptide-containing proteins encoded by A. oris possess multiple Cys residues, we propose that MdbA and VKOR constitute a major folding machine for the secretome of this organism. This oxidative protein folding pathway may be a common feature in Actinobacteria. PMID:26170452

  2. A Disulfide Bond-forming Machine Is Linked to the Sortase-mediated Pilus Assembly Pathway in the Gram-positive Bacterium Actinomyces oris.

    Science.gov (United States)

    Reardon-Robinson, Melissa E; Osipiuk, Jerzy; Chang, Chungyu; Wu, Chenggang; Jooya, Neda; Joachimiak, Andrzej; Das, Asis; Ton-That, Hung

    2015-08-28

    Export of cell surface pilins in Gram-positive bacteria likely occurs by the translocation of unfolded precursor polypeptides; however, how the unfolded pilins gain their native conformation is presently unknown. Here, we present physiological studies to demonstrate that the FimA pilin of Actinomyces oris contains two disulfide bonds. Alanine substitution of cysteine residues forming the C-terminal disulfide bridge abrogates pilus assembly, in turn eliminating biofilm formation and polymicrobial interaction. Transposon mutagenesis of A. oris yielded a mutant defective in adherence to Streptococcus oralis, and revealed the essential role of a vitamin K epoxide reductase (VKOR) gene in pilus assembly. Targeted deletion of vkor results in the same defects, which are rescued by ectopic expression of VKOR, but not a mutant containing an alanine substitution in its conserved CXXC motif. Depletion of mdbA, which encodes a membrane-bound thiol-disulfide oxidoreductase, abrogates pilus assembly and alters cell morphology. Remarkably, overexpression of MdbA or a counterpart from Corynebacterium diphtheriae, rescues the Δvkor mutant. By alkylation assays, we demonstrate that VKOR is required for MdbA reoxidation. Furthermore, crystallographic studies reveal that A. oris MdbA harbors a thioredoxin-like fold with the conserved CXXC active site. Consistently, each MdbA enzyme catalyzes proper disulfide bond formation within FimA in vitro that requires the catalytic CXXC motif. Because the majority of signal peptide-containing proteins encoded by A. oris possess multiple Cys residues, we propose that MdbA and VKOR constitute a major folding machine for the secretome of this organism. This oxidative protein folding pathway may be a common feature in Actinobacteria. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. A new approach to treatment of resistant gram-positive infections: potential impact of targeted IV to oral switch on length of stay

    Directory of Open Access Journals (Sweden)

    Trust Sarah

    2006-06-01

    Full Text Available Abstract Background Patients prescribed intravenous (IV glycopeptides usually remain in hospital until completion of this treatment. Some of these patients could be discharged earlier if a switch to an oral antibiotic was made. This study was designed to identify the percentage of inpatients currently prescribed IV glycopeptides who could be discharged earlier if a switch to an oral agent was used, and to estimate the number of bed days that could be saved. We also aimed to identify the patient group(s most likely to benefit, and to estimate the number of days of IV therapy that could be prevented in patients who remained in hospital. Methods Patients were included if they were prescribed an IV glycopeptide for 5 days or more. Predetermined IV to oral antibiotic switch criteria and discharge criteria were applied. A multiple logistic regression model was used to identify the characteristics of the patients most likely to be suitable for earlier discharge. Results Of 211 patients, 62 (29% could have had a reduced length of stay if they were treated with a suitable oral antibiotic. This would have saved a total of 649 inpatient days (median 5 per patient; range 1–54. A further 31 patients (15% could have switched to oral therapy as an inpatient thus avoiding IV line use. The patients most likely to be suitable for early discharge were those with skin and soft tissue infection, under the cardiology, cardiothoracic surgery, orthopaedics, general medical, plastic surgery and vascular specialities, with no high risk comorbidity and less than five other regularly prescribed drugs. Conclusion The need for glycopeptide therapy has a significant impact on length of stay. Effective targeting of oral antimicrobials could reduce the need for IV access, allow outpatient treatment and thus reduce the length of stay in patients with infections caused by antibiotic resistant gram-positive bacteria.

  4. Bacteria and fungi respond differently to multifactorial climate change in a temperate heathland, traced with 13C-Glycine and FACE CO2

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Dungait, Jennifer A.J.; Bol, Roland

    2014-01-01

    PLFAs for specific microbial groups (Gram positive bacteria, Gram negative bacteria, actinobacteria and fungi) was quantified using gas chromatography-combustion-stable isotope ratio mass spectrometry (GC-C-IRMS). Gram positive bacteria opportunistically utilized the freshly added glycine substrate, i...

  5. Exposure to Anacardiaceae Volatile Oils and Their Constituents Induces Lipid Peroxidation within Food-Borne Bacteria Cells

    Directory of Open Access Journals (Sweden)

    Ricardo M. Montanari

    2012-08-01

    Full Text Available The chemical composition of the volatile oils from five Anacardiaceae species and their activities against Gram positive and negative bacteria were assessed. The peroxidative damage within bacterial cell membranes was determined through the breakdown product malondialdehyde (MDA. The major constituents in Anacardium humile leaves oil were (E-caryophyllene (31.0% and α-pinene (22.0%, and in Anacardium occidentale oil they were (E-caryophyllene (15.4% and germacrene-D (11.5%. Volatile oil from Astronium fraxinifolium leaves were dominated by (E-β-ocimene (44.1% and α-terpinolene (15.2%, whilst the oil from Myracrodruon urundeuva contained an abundance of δ-3-carene (78.8%. However, Schinus terebinthifolius leaves oil collected in March and July presented different chemical compositions. The oils from all species, except the one from A. occidentale, exhibited varying levels of antibacterial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli. Oil extracted in July from S. terebinthifolius was more active against all bacterial strains than the corresponding oil extracted in March. The high antibacterial activity of the M. urundeuva oil could be ascribed to its high δ-3-carene content. The amounts of MDA generated within bacterial cells indicate that the volatile oils induce lipid peroxidation. The results suggest that one putative mechanism of antibacterial action of these volatile oils is pro-oxidant damage within bacterial cell membrane explaining in part their preservative properties.

  6. Can early MRI distinguish between Kingella kingae and Gram-positive cocci in osteoarticular infections in young children?

    Energy Technology Data Exchange (ETDEWEB)

    Kanavaki, Aikaterini; Hanquinet, Sylviane; Merlini, Laura [Geneva University Hospital HUG, Unit of Pediatric Radiology, Geneva (Switzerland); Ceroni, Dimitri [Geneva University Hospital, Unit of Pediatric Orthopedics, Geneva (Switzerland); Tchernin, David [Geneva University Hospital, Department of Radiology, Geneva (Switzerland)

    2012-01-15

    K. kingae is a common causative organism in acute osteoarticular infections (OAIs) in children under 4 years of age. Differentiation between K. kingae and Gram-positive cocci (GPC) is of great interest therapeutically. Our aim was to identify early distinguishing MRI features of OAIs. Thirty-one children younger than 4 years of age with OAI underwent MRI at presentation. Of these, 21 were caused by K. kingae and ten by GPC. Bone and soft tissue reaction, epiphyseal cartilage involvement, bone and subperiosteal abscess formation were compared between the two groups. Interobserver agreement was measured. Bone reaction was less frequent (P=0.0066) and soft tissue reaction less severe (P=0.0087) in the K. kingae group. Epiphysis cartilage abscesses were present only in the K. kingae group (P=0.0118). No difference was found for bone abscess (P=0.1411), subperiosteal abscess (P=1) or joint effusion (P=0.4414). Interobserver agreement was good for all criteria. MRI is useful in differentiating K. kingae from GPC in OAI. Cartilaginous involvement and modest soft tissue and bone reaction suggest K. kingae. (orig.)

  7. Modulation of Quorum Sensing in a Gram-Positive Pathogen by Linear Molecularly Imprinted Polymers with Anti-infective Properties.

    Science.gov (United States)

    Motib, Anfal; Guerreiro, Antonio; Al-Bayati, Firas; Piletska, Elena; Manzoor, Irfan; Shafeeq, Sulman; Kadam, Anagha; Kuipers, Oscar; Hiller, Luisa; Cowen, Todd; Piletsky, Sergey; Andrew, Peter W; Yesilkaya, Hasan

    2017-12-22

    We describe the development, characterization, and biological testing of a new type of linear molecularly imprinted polymer (LMIP) designed to act as an anti-infective by blocking the quorum sensing (QS) mechanism and so abrogating the virulence of the pathogen Streptococcus pneumoniae. The LMIP is prepared (polymerized) in presence of a template molecule, but unlike in traditional molecular imprinting approaches, no cross-linker is used. This results in soluble low-molecular-weight oligomers that can act as a therapeutic agent in vitro and in vivo. The LMIP was characterized by mass spectrometry to determine its monomer composition. Fragments identified were then aligned along the peptide template by computer modeling to predict the possible monomer sequence of the LMIP. These findings provide a proof of principle that LMIPs can be used to block QS, thus setting the stage for the development of LMIPs a novel drug-discovery platform and class of materials to target Gram-positive pathogens. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Antimicrobial resistance in gram-positive pathogens isolated in the UK between October 1996 and January 1997.

    Science.gov (United States)

    Andrews, J; Ashby, J; Jevons, G; Lines, N; Wise, R

    1999-05-01

    Antimicrobial resistance in gram-positive pathogens from 30 centres in the UK (ten Teaching, ten Associate Teaching and ten District General Hospitals) was studied over a 4 month period between October 1996 and January 1997. High-level resistance (HLR) and low-level resistance (LLR) to penicillin amongst pneumococci was 3.3% and 3.4%, respectively. However, considerable variation in resistance rates was observed depending on geographical location (LLR range 0-15.4% and HLR range 0-30.8%). Considerable variation in resistance rates was also observed for Staphylococcus aureus to methicillin, with rates ranging from 0% to 56.7% depending on locality. Using conventional MIC methodology, none of the isolates of S. aureus was considered as having reduced sensitivity to vancomycin. However, eight isolates grew on Brain Heart Infusion Agar containing vancomycin (4 mg/L) after prolonged incubation and are therefore worthy of further investigation by electron microscopy. With Enterococcus faecalis, resistance rates were similar between the three types of hospital and only four isolates were considered resistant to glycopeptide antibiotics (one vanA and three vanB phenotype).

  9. Evaluation of the automated system Vitek2 for identification and antimicrobial susceptibility testing of Brazilian Gram-positive cocci strains

    Directory of Open Access Journals (Sweden)

    Pedro Alves d'Azevedo

    Full Text Available Automated instruments offer many advantages for clinical laboratories. Nevertheless, they can have problems identifying and determining susceptibilities of some pathogens. Vitek® 2 (bioMérieux is an automated system that was recently introduced to Brazil. We evaluated the performance of this equipment for Brazilian isolates that had been characterized using reference identification and antimicrobial susceptibility testing methods. Ninety-nine strains of Gram-positive cocci from a local reference center collection were analyzed, consisting of 50 coagulasenegative Staphylococcus (CoNS and 49 Enterococcus and related species. Vitek® 2 correctly identified 79.8% (79/99 of the isolates. Oxacillin resistance was detected in 76% (19/25 of resistant S. epidermidis strains and in 88% (22/25 of other resistant CoNS species strains. Vancomycin resistance was detected in 100% (20/20 of resistant Enterococcus and related species strains. Vitek® 2 performed very well for the identification of S. epidermidis and non-epidermidis staphylococci, and for the detection of vancomycin resistance in Enterococcus and related species. However, the system needs improvement in order to provide reliable results for the characterization of some CoNS species, identification of Enterococcus and related species and for detecting oxacillin resistance in CoNS.

  10. Changes of the Quinolones Resistance to Gram-positive Cocci Isolated during the Past 8 Years in the First Bethune Hospital

    Science.gov (United States)

    Xu, Jiancheng; Chen, Qihui; Yao, Hanxin; Zhou, Qi

    This study was to investigate the quinolones resistance to gram-positive cocci isolated in the First Bethune Hospital during the past 8 years. Disk diffusion test was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococci (MRCNS) were 50.8%∼83.3% and 79.4%∼81.5%during the past 8 years, respectively. In recent 8 years, the quinolones resistance to gram-positive cocci had increased. Monitoring of the quinolones resistance to gram-positive cocci should be strengthened. The change of the antimicrobial resistance should be investigated in order to guide rational drug usage in the clinic and prevent bacterial strain of drug resistance from being transmitted.

  11. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    International Nuclear Information System (INIS)

    Lunov, O.; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

    2015-01-01

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy

  12. The antimicrobial spectra of selected Penicillia against some pathogenic bacteria and yeasts

    Directory of Open Access Journals (Sweden)

    Shashi Chauhan

    2014-08-01

    Full Text Available The antagonista activity of eight isolaies of penicillia bas been studied against 13 pathogenic organisms, which included 6 Gram-positive bacteria, 4 Gram-negative bacteria and 3 yeasts.

  13. Genome sequence of Desulfitobacterium hafniense DCB-2, a Gram-positive anaerobe capable of dehalogenation and metal reduction

    Directory of Open Access Journals (Sweden)

    Kim Sang-Hoon

    2012-02-01

    Full Text Available Abstract Background The genome of the Gram-positive, metal-reducing, dehalorespiring Desulfitobacterium hafniense DCB-2 was sequenced in order to gain insights into its metabolic capacities, adaptive physiology, and regulatory machineries, and to compare with that of Desulfitobacterium hafniense Y51, the phylogenetically closest strain among the species with a sequenced genome. Results The genome of Desulfitobacterium hafniense DCB-2 is composed of a 5,279,134-bp circular chromosome with 5,042 predicted genes. Genome content and parallel physiological studies support the cell's ability to fix N2 and CO2, form spores and biofilms, reduce metals, and use a variety of electron acceptors in respiration, including halogenated organic compounds. The genome contained seven reductive dehalogenase genes and four nitrogenase gene homologs but lacked the Nar respiratory nitrate reductase system. The D. hafniense DCB-2 genome contained genes for 43 RNA polymerase sigma factors including 27 sigma-24 subunits, 59 two-component signal transduction systems, and about 730 transporter proteins. In addition, it contained genes for 53 molybdopterin-binding oxidoreductases, 19 flavoprotein paralogs of the fumarate reductase, and many other FAD/FMN-binding oxidoreductases, proving the cell's versatility in both adaptive and reductive capacities. Together with the ability to form spores, the presence of the CO2-fixing Wood-Ljungdahl pathway and the genes associated with oxygen tolerance add flexibility to the cell's options for survival under stress. Conclusions D. hafniense DCB-2's genome contains genes consistent with its abilities for dehalogenation, metal reduction, N2 and CO2 fixation, anaerobic respiration, oxygen tolerance, spore formation, and biofilm formation which make this organism a potential candidate for bioremediation at contaminated sites.

  14. Salirhabdus euzebyi gen. nov., sp. nov., a Gram-positive, halotolerant bacterium isolated from a sea salt evaporation pond.

    Science.gov (United States)

    Albuquerque, Luciana; Tiago, Igor; Rainey, Fred A; Taborda, Marco; Nobre, M Fernanda; Veríssimo, António; da Costa, Milton S

    2007-07-01

    A low-G+C, Gram-positive bacterium, designated CVS-14(T), was recovered from a sea salt evaporation pond on the island of Sal in the Cape Verde Archipelago. This organism was catalase- and oxidase-positive. Cells were motile, spore-forming aerobic rods, with an optimum growth temperature of about 35-40 degrees C and optimum pH between 7.0 and 8.5. Optimal growth occurred in media containing 4-6 % (w/v) NaCl, although the organism was able to grow in medium without added NaCl and in medium containing 16 % NaCl. The cell-wall peptidoglycan was of A1 gamma type and the major respiratory quinone was menaquinone 7 (MK-7). Major fatty acids were iso-15 : 0, anteiso-15 : 0, iso-17 : 0 and anteiso-17 : 0. The DNA G+C content was 37.0 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain CVS-14(T) formed a distinct new branch within the radiation of the moderately halophilic bacilli group, forming a separate lineage from species of the genera Salinibacillus, Paucisalibacillus, Oceanobacillus, Lentibacillus and Virgibacillus. Strain CVS-14(T) showed 16S rRNA gene pairwise similarity values of approximately 95 % with species of the genus Salinibacillus. On the basis of morphological, physiological, chemotaxonomic and phylogenetic characteristics, strain CVS-14(T) is considered to represent a novel species in a new genus, for which the name Salirhabdus euzebyi gen. nov., sp. nov. is proposed. The type strain is CVS-14(T) (=LMG 22839(T)=CIP 108577(T)).

  15. Comparative in vitro activities of trovafloxacin (CP-99,219) against 445 gram-positive isolates from patients with endocarditis and those with other bloodstream infections

    NARCIS (Netherlands)

    H.P. Endtz (Hubert); J.W. Mouton (Johan); J.G. den Hollander (Jan); N.P.W.C.J. van den Braak (Nicole); H.A. Verbrugh (Henri)

    1997-01-01

    textabstractThe in vitro activity of trovafloxacin (CP-99,219), a new fluoroquinolone, was compared with the in vitro activities of other commonly used quinolones and other antimicrobial agents against 445 gram-positive microorganisms isolated between 1986 and 1995 from

  16. A pathway closely related to the (D)-tagatose pathway of gram-negative enterobacteria identified in the gram-positive bacterium Bacillus licheniformis.

    Science.gov (United States)

    Van der Heiden, Edwige; Delmarcelle, Michaël; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M; Galleni, Moreno; Joris, Bernard

    2013-06-01

    We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus.

  17. A Pathway Closely Related to the d-Tagatose Pathway of Gram-Negative Enterobacteria Identified in the Gram-Positive Bacterium Bacillus licheniformis

    Science.gov (United States)

    Van der Heiden, Edwige; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M.; Galleni, Moreno; Joris, Bernard

    2013-01-01

    We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus. PMID:23524682

  18. A Pathway Closely Related to the d-Tagatose Pathway of Gram-Negative Enterobacteria Identified in the Gram-Positive Bacterium Bacillus licheniformis

    OpenAIRE

    Van der Heiden, Edwige; Delmarcelle, Michaël; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M.; Galleni, Moreno; Joris, Bernard

    2013-01-01

    We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus.

  19. Evaluation of the LightCycler Staphylococcus M GRADE kits on positive blood cultures that contained gram-positive cocci in clusters.

    Science.gov (United States)

    Shrestha, Nabin K; Tuohy, Marion J; Padmanabhan, Ravindran A; Hall, Gerri S; Procop, Gary W

    2005-12-01

    We evaluated the Roche LightCycler Staphylococcus M(GRADE) kits to differentiate between Staphylococcus aureus and coagulase-negative staphylococci in blood cultures growing clusters of gram-positive cocci. Testing 100 bottles (36 containing S. aureus), the assay was 100% sensitive and 98.44% specific for S. aureus and 100% sensitive and specific for coagulase-negative staphylococci.

  20. Higher order structure in the 3'-minor domain of small subunit ribosomal RNAs from a gram negative bacterium, a gram positive bacterium and a eukaryote

    DEFF Research Database (Denmark)

    Douthwaite, S; Christensen, A; Garrett, R A

    1983-01-01

    of additional higher order structure in the renatured free RNA. It can be concluded that a high level of conservation of higher order structure has occurred during the evolution of the gram negative and gram positive eubacteria and the eukaryote in both the double helical regions and the "unstructured" regions...

  1. Supernatants from Staphylococcus epidermidis grown in the presence of different antibiotics induce differential release of tumor necrosis factor alpha from human monocytes.

    OpenAIRE

    Mattsson, E; Van Dijk, H; Verhoef, J; Norrby, R; Rollof, J

    1996-01-01

    Bacterial products from gram-positive bacteria, such as peptidoglycan, teichoic acid, and toxins, activate mononuclear cells to produce tumor necrosis factor alpha (TNF). The present study evaluated the release of soluble cell wall components from Staphylococcus epidermidis capable of inducing TNF after exposure of the bacteria to various antibiotics. A clinical S. epidermidis isolate (694) was incubated with either penicillin, oxacillin, vancomycin, or clindamycin at five times the MIC. Supe...

  2. Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

    Science.gov (United States)

    D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

    2014-12-01

    The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

  3. Overcoming function annotation errors in the Gram-positive pathogen Streptococcus suis by a proteomics-driven approach

    Directory of Open Access Journals (Sweden)

    Bárcena José A

    2008-12-01

    Full Text Available Abstract Background Annotation of protein-coding genes is a key step in sequencing projects. Protein functions are mainly assigned on the basis of the amino acid sequence alone by searching of homologous proteins. However, fully automated annotation processes often lead to wrong prediction of protein functions, and therefore time-intensive manual curation is often essential. Here we describe a fast and reliable way to correct function annotation in sequencing projects, focusing on surface proteomes. We use a proteomics approach, previously proven to be very powerful for identifying new vaccine candidates against Gram-positive pathogens. It consists of shaving the surface of intact cells with two proteases, the specific cleavage-site trypsin and the unspecific proteinase K, followed by LC/MS/MS analysis of the resulting peptides. The identified proteins are contrasted by computational analysis and their sequences are inspected to correct possible errors in function prediction. Results When applied to the zoonotic pathogen Streptococcus suis, of which two strains have been recently sequenced and annotated, we identified a set of surface proteins without cytoplasmic contamination: all the proteins identified had exporting or retention signals towards the outside and/or the cell surface, and viability of protease-treated cells was not affected. The combination of both experimental evidences and computational methods allowed us to determine that two of these proteins are putative extracellular new adhesins that had been previously attributed a wrong cytoplasmic function. One of them is a putative component of the pilus of this bacterium. Conclusion We illustrate the complementary nature of laboratory-based and computational methods to examine in concert the localization of a set of proteins in the cell, and demonstrate the utility of this proteomics-based strategy to experimentally correct function annotation errors in sequencing projects. This

  4. In vivo metabolism of 2,2'-diaminopimelic acid from gram-positive and gram-negative bacterial cells by ruminal microorganisms and ruminants and its use as a marker of bacterial biomass

    International Nuclear Information System (INIS)

    Masson, H.A.; Denholm, A.M.; Ling, J.R.

    1991-01-01

    Cells of Bacillus megaterium GW1 and Escherichia coli W7-M5 were specifically radiolabeled with 2,2'-diamino [G- 3 H] pimelic acid ([ 3 H]DAP) as models of gram-positive and gram-negative bacteria, respectively. Two experiments were conducted to study the in vivo metabolism of 2,2'-diaminopimelic acid (DAP) in sheep. In experiment 1, cells of [ 3 H]DAP-labeled B. megaterium GW1 were infused into the rumen of one sheep and the radiolabel was traced within microbial samples, digesta, and the whole animal. Bacterially bound [ 3 H]DAP was extensively metabolized, primarily (up to 70% after 8 h) via decarboxylation to [ 3 H]lysine by both ruminal protozoa and ruminal bacteria. Recovery of infused radiolabel in urine and feces was low (42% after 96 h) and perhaps indicative of further metabolism by the host animal. In experiment 2, [ 3 H]DAP-labeled B. megaterium GW1 was infused into the rumens of three sheep and [ 3 H]DAP-labeled E. coli W7-W5 was infused into the rumen of another sheep. The radioactivity contents of these mutant bacteria were insufficient to use as tracers, but the metabolism of DAP was monitored in the total, free, and peptidyl forms. Free DAP, as a proportion of total DPA in duodenal digesta, varied from 0 to 9.5%, whereas peptidyl DAP accounted for 8.3 to 99.2%

  5. Regulatory RNAs in Bacillus subtilis : a Gram-Positive Perspective on Bacterial RNA-Mediated Regulation of Gene Expression

    NARCIS (Netherlands)

    Mars, Ruben A. T.; Nicolas, Pierre; Denham, Emma L.; van Dijl, Jan Maarten

    2016-01-01

    Bacteria can employ widely diverse RNA molecules to regulate their gene expression. Such molecules include trans-acting small regulatory RNAs, antisense RNAs, and a variety of transcriptional attenuation mechanisms in the 5= untranslated region. Thus far, most regulatory RNA research has focused on

  6. Evaluation of a fluorescent lectin-based staining technique for some acidophilic mining bacteria

    International Nuclear Information System (INIS)

    Fife, D.J.; Bruhn, D.F.; Miller, K.S.; Stoner, D.L.

    2000-01-01

    A fluorescence-labeled wheat germ agglutinin staining technique was modified and found to be effective for staining gram-positive, acidophilic mining bacteria. Bacteria identified by others as being gram positive through 16S rRNA sequence analyses, yet clustering near the divergence of that group, stained weakly. Gram-negative bacteria did not stain. Background staining of environmental samples was negligible, and pyrite and soil particles in the samples did not interfere with the staining procedure

  7. Assessing the interactions of a natural antibacterial clay with model Gram-positive and Gram-negative human pathogens

    Science.gov (United States)

    Londono, S. C.; Williams, L. B.

    2013-12-01

    The emergence of antibiotic resistant bacteria and increasing accumulations of antibiotics in reclaimed water, drive the quest for new natural antimicrobials. We are studying the antibacterial mechanism(s) of clays that have shown an ability to destroy bacteria or significantly inhibit their growth. One possible mode of action is from soluble transition metal species, particularly reduced Fe, capable of generating deleterious oxygen radical species. Yet another possibility is related to membrane damage as a consequence of physical or electrostatic interaction between clay and bacteria. Both mechanisms could combine to produce cell death. This study addresses a natural antibacterial clay from the NW Amazon basin, South America (AMZ clay). Clay mineralogy is composed of disordered kaolinite (28.9%), halloysite (17.8%) illite (12%) and smectite (16.7%). Mean particle size is 1.6μm and total and specific surface area 278.82 and 51.23 m2/g respectively. The pH of a suspension (200mg/ml) is 4.1 and its Eh is 361mV after 24h of equilibration. The ionic strength of the water in equilibrium with the clay after 24 h. is 6 x10-4M. These conditions, affect the element solubility, speciation, and interactions between clay and bacteria. Standard microbiological methods were used to assess the viability of two model bacteria (Escherichia coli and Bacillus subtilis) after incubation with clay at 37 degC for 24 hrs. A threefold reduction in bacterial viability was observed upon treatment with AMZ clay. We separated the cells from the clay using Nycodenz gradient media and observed the mounts under the TEM and SEM. Results showed several membrane anomalies and structural changes that were not observed in the control cells. Additionally, clay minerals appeared in some places attached to cell walls. Experiments showed that exchanging AMZ clay with KCl caused loss of antibacterial property. Among the exchangeable -and potentially toxic- ions we measured Al+3, Cu+2, Zn+2, Ba+2 and Co+2

  8. The origin of a derived superkingdom: how a gram-positive bacterium crossed the desert to become an archaeon

    Directory of Open Access Journals (Sweden)

    Bourne Philip E

    2011-02-01

    Full Text Available Abstract Background The tree of life is usually rooted between archaea and bacteria. We have previously presented three arguments that support placing the root of the tree of life in bacteria. The data have been dismissed because those who support the canonical rooting between the prokaryotic superkingdoms cannot imagine how the vast divide between the prokaryotic superkingdoms could be crossed. Results We review the evidence that archaea are derived, as well as their biggest differences with bacteria. We argue that using novel data the gap between the superkingdoms is not insurmountable. We consider whether archaea are holophyletic or paraphyletic; essential to understanding their origin. Finally, we review several hypotheses on the origins of archaea and, where possible, evaluate each hypothesis using bioinformatics tools. As a result we argue for a firmicute ancestry for archaea over proposals for an actinobacterial ancestry. Conclusion We believe a synthesis of the hypotheses of Lake, Gupta, and Cavalier-Smith is possible where a combination of antibiotic warfare and viral endosymbiosis in the bacilli led to dramatic changes in a bacterium that resulted in the birth of archaea and eukaryotes. Reviewers This article was reviewed by Patrick Forterre, Eugene Koonin, and Gáspár Jékely

  9. Activation of type III interferon genes by pathogenic bacteria in infected epithelial cells and mouse placenta.

    Directory of Open Access Journals (Sweden)

    Hélène Bierne

    Full Text Available Bacterial infections trigger the expression of type I and II interferon genes but little is known about their effect on type III interferon (IFN-λ genes, whose products play important roles in epithelial innate immunity against viruses. Here, we studied the expression of IFN-λ genes in cultured human epithelial cells infected with different pathogenic bacteria and in the mouse placenta infected with Listeria monocytogenes. We first showed that in intestinal LoVo cells, induction of IFN-λ genes by L. monocytogenes required bacterial entry and increased further during the bacterial intracellular phase of infection. Other Gram-positive bacteria, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis, also induced IFN-λ genes when internalized by LoVo cells. In contrast, Gram-negative bacteria Salmonella enterica serovar Typhimurium, Shigella flexneri and Chlamydia trachomatis did not substantially induce IFN-λ. We also found that IFN-λ genes were up-regulated in A549 lung epithelial cells infected with Mycobacterium tuberculosis and in HepG2 hepatocytes and BeWo trophoblastic cells infected with L. monocytogenes. In a humanized mouse line permissive to fetoplacental listeriosis, IFN-λ2/λ3 mRNA levels were enhanced in placentas infected with L. monocytogenes. In addition, the feto-placental tissue was responsive to IFN-λ2. Together, these results suggest that IFN-λ may be an important modulator of the immune response to Gram-positive intracellular bacteria in epithelial tissues.

  10. Association of sexually transmitted infections, Candida species, gram-positive flora and perianal flora with bacterial vaginosis.

    Science.gov (United States)

    Vahidnia, Ali; Tuin, Hellen; Bliekendaal, Harry; Spaargaren, Joke

    2015-10-01

    Bacterial vaginosis (BV) is characterised by depletion of the normal Lactobacillus spp. and overgrowth of commensal anaerobic bacteria. We investigated the composition of vaginal microbiota and their association with BV in women of reproductive age. Vaginal samples from 1197 women were analysed, whereby n=451 patients had normal flora and n=614 were diagnosed with BV, the remaining patients were diagnosed with having either intermediate flora (n=42) or dysbacteriosis (n=90). The reported results show that pathogens are associated with BV. This knowledge will further expand our understanding of events leading to BV, which may lead to more effective prevention and treatment strategies.

  11. Heme and menaquinone induced electron transport in lactic acid bacteria

    OpenAIRE

    Brooijmans, Rob; Smit, Bart; Santos, Filipe; van Riel, Jan; de Vos, Willem M; Hugenholtz, Jeroen

    2009-01-01

    Abstract Background For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait. Results Heme- (and menaquinone) stimulated aerobic growth was observed for several species and genera of lactic acid bacteria. These include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacill...

  12. Influence of complement on neutrophil extracellular trap release induced by bacteria

    DEFF Research Database (Denmark)

    Palmer, Lisa Joanne; Damgaard, Christian; Holmstrup, Palle

    2016-01-01

    by Staphylococcus aureus and three oral bacteria: Actinomyces viscosus, Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum subsp. vincettii. Material and Methods Bacteria-stimulated NET release from the neutrophils of healthy donors was measured fluorometrically. Various complement containing...... In conclusion, complement opsonization promotes NET release induced by a variety of bacteria, including A. actinomycetemcomitans, and CR1 plays a dominant role in the process. Complement consumption or deficiency may compromise NETosis induced by some bacterial species, including A. actinomycetemcomitans....... Within biofilms, the complement-inactivating abilities of some bacteria may protect other species against NETosis, while these are more vulnerable when adopting a planktonic lifestyle....

  13. Heme and menaquinone induced electron transport in lactic acid bacteria

    NARCIS (Netherlands)

    Brooijmans, R.J.W.; Smit, B.; Santos, dos F.; Riel, van J.; Vos, de W.M.; Hugenholtz, J.

    2009-01-01

    ABSTRACT: BACKGROUND: For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait.

  14. Expansion of a plasmid classification system for Gram-positive bacteria and determination of the diversity of plasmids in Staphylococcus aureus strains of human, animal, and food origins

    DEFF Research Database (Denmark)

    Lozano, C.; Garcia-Migura, L.; Aspiroz, C.

    2012-01-01

    An expansion of a previously described plasmid classification was performed and used to reveal the plasmid content of a collection of 92 Staphylococcus aureus strains of different origins. rep genes of other genera were detected in Staphylococcus. S1 pulsed-field gel electrophoresis (PFGE) hybrid...

  15. Comparative analysis of twin-arginine (Tat)-dependent protein secretion of a heterologous model protein (GFP) in three different Gram-positive bacteria

    NARCIS (Netherlands)

    Meissner, Daniel; Vollstedt, Angela; van Dijl, Jan Maarten; Freudl, Roland

    In contrast to the general protein secretion (Sec) system, the twin-arginine translocation (Tat) export pathway allows the translocation of proteins across the bacterial plasma membrane in a fully folded conformation. Due to this feature, the Tat pathway provides an attractive alternative to the

  16. Dimeric cyanobacterial cyclopent-4-ene-1,3-dione as selective inhibitor of Gram-positive bacteria growth: Bio-production approach and preparative isolation by HPCCC

    Czech Academy of Sciences Publication Activity Database

    Cheel, José; Bogdanová, K.; Ignatova, S.; Garrard, I.; Hewitson, P.; Kolář, M.; Kopecký, Jiří; Hrouzek, Pavel; Vacek, J.

    2016-01-01

    Roč. 18, SEP (2016), s. 244-249 ISSN 2211-9264 R&D Projects: GA MŠk EE2.3.30.0059; GA MŠk ED2.1.00/03.0110; GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : Phenolic cyclopentenedione * Natural antibiotic * Cyanobacteria Subject RIV: EE - Microbiology, Virology Impact factor: 3.994, year: 2016

  17. Differential staining of bacteria: gram stain.

    Science.gov (United States)

    Moyes, Rita B; Reynolds, Jackie; Breakwell, Donald P

    2009-11-01

    In 1884, Hans Christian Gram, a Danish doctor, developed a differential staining technique that is still the cornerstone of bacterial identification and taxonomic division. This multistep, sequential staining protocol separates bacteria into four groups based on cell morphology and cell wall structure: Gram-positive cocci, Gram-negative cocci, Gram-positive rods, and Gram-negative rods. The Gram stain is useful for assessing bacterial contamination of tissue culture samples or for examining the Gram stain status and morphological features of bacteria isolated from mixed or isolated bacterial cultures. (c) 2009 by John Wiley & Sons, Inc.

  18. Pleural effusion adenosine deaminase: a candidate biomarker to discriminate between Gram-negative and Gram-positive bacterial infections of the pleural space

    Directory of Open Access Journals (Sweden)

    Ruolin Li

    2016-05-01

    Full Text Available OBJECTIVES: Delay in the treatment of pleural infection may contribute to its high mortality. In this retrospective study, we aimed to evaluate the diagnostic accuracy of pleural adenosine deaminase in discrimination between Gram-negative and Gram-positive bacterial infections of the pleural space prior to selecting antibiotics. METHODS: A total of 76 patients were enrolled and grouped into subgroups according to Gram staining: 1 patients with Gram-negative bacterial infections, aged 53.2±18.6 years old, of whom 44.7% had empyemas and 2 patients with Gram-positive bacterial infections, aged 53.5±21.5 years old, of whom 63.1% had empyemas. The pleural effusion was sampled by thoracocentesis and then sent for adenosine deaminase testing, biochemical testing and microbiological culture. The Mann-Whitney U test was used to examine the differences in adenosine deaminase levels between the groups. Correlations between adenosine deaminase and specified variables were also quantified using Spearman’s correlation coefficient. Moreover, receiver operator characteristic analysis was performed to evaluate the diagnostic accuracy of pleural effusion adenosine deaminase. RESULTS: Mean pleural adenosine deaminase levels differed significantly between Gram-negative and Gram-positive bacterial infections of the pleural space (191.8±32.1 U/L vs 81.0±16.9 U/L, p<0.01. The area under the receiver operator characteristic curve was 0.689 (95% confidence interval: 0.570, 0.792, p<0.01 at the cutoff value of 86 U/L. Additionally, pleural adenosine deaminase had a sensitivity of 63.2% (46.0-78.2%; a specificity of 73.7% (56.9-86.6%; positive and negative likelihood ratios of 2.18 and 0.50, respectively; and positive and negative predictive values of 70.6% and 66.7%, respectively. CONCLUSIONS: Pleural effusion adenosine deaminase is a helpful alternative biomarker for early and quick discrimination of Gram-negative from Gram-positive bacterial infections of the

  19. Antimicrobial susceptibility trends among gram-positive and -negative clinical isolates collected between 2005 and 2012 in Mexico: results from the Tigecycline Evaluation and Surveillance Trial.

    Science.gov (United States)

    Morfin-Otero, Rayo; Noriega, Eduardo Rodriguez; Dowzicky, Michael J

    2015-12-15

    The Tigecycline Evaluation and Surveillance Trial (T.E.S.T) is a global antimicrobial surveillance study of both gram-positive and gram-negative organisms. This report presents data on antimicrobial susceptibility among organisms collected in Mexico between 2005 and 2012 as part of T.E.S.T., and compares rates between 2005-2007 and 2008-2012. Each center in Mexico submitted at least 200 isolates per collection year; including 65 gram-positive isolates and 135 gram-negative isolates. Minimum inhibitory concentrations (MICs) were determined using Clinical Laboratory Standards Institute (CLSI) broth microdilution methodology and antimicrobial susceptibility was established using the 2013 CLSI-approved breakpoints. For tigecycline US Food and Drug Administration (FDA) breakpoints were applied. Isolates of E. coli and K. pneumoniae with a MIC for ceftriaxone of >1 mg/L were screened for ESBL production using the phenotypic confirmatory disk test according to CLSI guidelines. The rates of some key resistant phenotypes changed during this study: vancomycin resistance among Enterococcus faecium decreased from 28.6 % in 2005-2007 to 19.1 % in 2008-2012, while β-lactamase production among Haemophilus influenzae decreased from 37.6 to 18.9 %. Conversely, methicillin-resistant Staphylococcus aureus increased from 38.1 to 47.9 %, meropenem-resistant Acinetobacter spp. increased from 17.7 to 33.0 % and multidrug-resistant Acinetobacter spp. increased from 25.6 to 49.7 %. The prevalence of other resistant pathogens was stable over the study period, including extended-spectrum β-lactamase-positive Escherichia coli (39.0 %) and Klebsiella pneumoniae (25.0 %). The activity of tigecycline was maintained across the study years with MIC90s of ≤2 mg/L against Enterococcus spp., S. aureus, Streptococcus agalactiae, Streptococcus pneumoniae, Enterobacter spp., E. coli, K. pneumoniae, Klebsiella oxytoca, Serratia marcescens, H. influenzae, and Acinetobacter spp. All gram-positive

  20. Thymidine kinase diversity in bacteria

    DEFF Research Database (Denmark)

    Sandrini, Michael; Clausen, A.R.; Munch-Petersen, B.

    2006-01-01

    Thymidine kinases (TKs) appear to be almost ubiquitous and are found in nearly all prokaryotes, eukaryotes, and several viruses. They are the key enzymes in thymidine salvage and activation of several anti-cancer and antiviral drugs. We show that bacterial TKs can be subdivided into 2 groups. The....... The TKs from Gram-positive bacteria are more closely related to the eukaryotic TK1 enzymes than are TKs from Gram-negative bacteria....

  1. Isolation and Purification of an Antibacterial Protein from Immune Induced Haemolymph of American Cockroach, Periplaneta americana

    Directory of Open Access Journals (Sweden)

    Hamid Reza Basseri

    2016-10-01

    Full Text Available Background: Antimicrobial peptides play a role as effectors substances in the immunity of vertebrate and inverte­brate hosts. In the current study, antimicrobial peptide was isolated from the haemolymph of the American cock­roach, Periplaneta americana.Methods: Micrococcus luteus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria were candi­date for injection. Induction was done by injecting both bacteria into the abdominal cavity of two groups of cock­roaches separately. The haemolymphs were collected 24 hours after post injection and initially tested against both bacteria. Subsequently, the immune induced haemolymph was purified by high performance liquid chromatography (HPLC to separate the proteins responsible for the antibacterial activity.Results: The non-induced haemolymph did not show any activity against both bacteria whereas induced haemo­lymph exhibited high activity against M. luteus but did less against E. coli. Two fractions showed antibacterial activ­ity against M. luteus. Finally the molecular weight of the isolated antibacterial proteins were determined as 72 kDa and 62 kDa using SDS-PAGE.Conclusion: Induced haemolymph of American cockroaches has the ability to produce peptides to combat against Gram-positive bacteria when an immune challenge is mounted. Further work has to be done to sequence of the pro­tein, which it would be advantageous.

  2. Antimicrobial susceptibility of quinupristin/dalfopristin tested against gram-positive cocci from Latin America: results from the Global SMART (GSMART surveillance study

    Directory of Open Access Journals (Sweden)

    Sader Helio S.

    2001-01-01

    Full Text Available Gram-positive cocci are important causes of both nosocomial and community-acquired infections, and antimicrobial resistance among these pathogens has become an important problem worldwide. Since resistance among these organisms can vary substantially by geographic location, we conducted a multicenter surveillance study with isolates from five Latin American countries (15 medical centers. Quinupristin/dalfopristin (formerly RP-59500 is a novel streptogramin combination with focused activity against Gram-positive cocci, many exhibiting emerging resistance. The in vitro activity of quinupristin/dalfopristin and 12 other antimicrobial agents were evaluated against 1,948 strains including Staphylococcus aureus (747 strains, coagulase-negative staphylococci (CoNS; 446 strains, enterococci (429 strains, and various Streptococcus spp. (326 strains. Oxacillin resistance was observed in 41% of S. aureus (MIC, or = 13 mm and 40% of CoNS (MIC, or = 18 mm. Vancomycin, teicoplanin, and quinupristin/dalfopristin (MIC90, 0.25 - 1 mug/ml remained effective against all strains, but cross-resistance was high among other tested drugs. The quinupristin/dalfopristin MIC50 for Streptococcus pneumoniae and other streptococci was only 0.5 mug/ml (13% to 28% were penicillin-resistant; 12% to 22% were macrolide-resistant. Enterococci demonstrated variable inhibition by quinupristin/dalfopristin depending upon identification and the susceptibility testing method used. The demonstrated quinupristin/dalfopristin activity against Enterococcus faecium was confirmed, but potential species identification errors with various commercial systems continue to confuse susceptibility statistics, even though some strains of E. faecium confirmed by PCR-based or other molecular identification techniques did have quinupristin/dalfopristin MICs of > or = 4 mug/mL. Most important, glycopeptide-resistant enterococci are rapidly emerging in Latin America, and quinupristin/dalfopristin appears

  3. Multi-location gram-positive and gram-negative bacterial protein subcellular localization using gene ontology and multi-label classifier ensemble.

    Science.gov (United States)

    Wang, Xiao; Zhang, Jun; Li, Guo-Zheng

    2015-01-01

    It has become a very important and full of challenge task to predict bacterial protein subcellular locations using computational methods. Although there exist a lot of prediction methods for bacterial proteins, the majority of these methods can only deal with single-location proteins. But unfortunately many multi-location proteins are located in the bacterial cells. Moreover, multi-location proteins have special biological functions capable of helping the development of new drugs. So it is necessary to develop new computational methods for accurately predicting subcellular locations of multi-location bacterial proteins. In this article, two efficient multi-label predictors, Gpos-ECC-mPLoc and Gneg-ECC-mPLoc, are developed to predict the subcellular locations of multi-label gram-positive and gram-negative bacterial proteins respectively. The two multi-label predictors construct the GO vectors by using the GO terms of homologous proteins of query proteins and then adopt a powerful multi-label ensemble classifier to make the final multi-label prediction. The two multi-label predictors have the following advantages: (1) they improve the prediction performance of multi-label proteins by taking the correlations among different labels into account; (2) they ensemble multiple CC classifiers and further generate better prediction results by ensemble learning; and (3) they construct the GO vectors by using the frequency of occurrences of GO terms in the typical homologous set instead of using 0/1 values. Experimental results show that Gpos-ECC-mPLoc and Gneg-ECC-mPLoc can efficiently predict the subcellular locations of multi-label gram-positive and gram-negative bacterial proteins respectively. Gpos-ECC-mPLoc and Gneg-ECC-mPLoc can efficiently improve prediction accuracy of subcellular localization of multi-location gram-positive and gram-negative bacterial proteins respectively. The online web servers for Gpos-ECC-mPLoc and Gneg-ECC-mPLoc predictors are freely accessible

  4. Inducible secretion of phytate-degrading enzymes from bacteria ...

    African Journals Online (AJOL)

    aghomotsegin

    2015-02-04

    Feb 4, 2015 ... Key words: Bacillus sp., phytase activities, soil bacteria, Bacillus broth, Bacillus broth. INTRODUCTION ... Penicillium) enzymes conquered many applications in ... U/(g×h)] than in (SSF) Solid State Fermentation [1.2. U/(g×h)] ... mM (from Loba Chemie Pvt. Ltd, Mumbai), and liquid nitrogen (from. Air liquid ...

  5. Heme and menaquinone induced electron transport in lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Santos Filipe

    2009-05-01

    Full Text Available Abstract Background For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait. Results Heme- (and menaquinone stimulated aerobic growth was observed for several species and genera of lactic acid bacteria. These include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacilllus brevis, Lactobacillus paralimentarius, Streptococcus entericus and Lactococcus garviae. The increased biomass production without further acidification, which are respiration associated traits, are suitable for high-throughput screening as demonstrated by the screening of 8000 Lactococcus lactis insertion mutants. Respiration-negative insertion-mutants were found with noxA, bd-type cytochrome and menaquinol biosynthesis gene-disruptions. Phenotypic screening and in silico genome analysis suggest that respiration can be considered characteristic for certain species. Conclusion We propose that the cyd-genes were present in the common ancestor of lactic acid bacteria, and that multiple gene-loss events best explains the observed distribution of these genes among the species.

  6. Heme and menaquinone induced electron transport in lactic acid bacteria.

    Science.gov (United States)

    Brooijmans, Rob; Smit, Bart; Santos, Filipe; van Riel, Jan; de Vos, Willem M; Hugenholtz, Jeroen

    2009-05-29

    For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait. Heme- (and menaquinone) stimulated aerobic growth was observed for several species and genera of lactic acid bacteria. These include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacilllus brevis, Lactobacillus paralimentarius, Streptococcus entericus and Lactococcus garviae. The increased biomass production without further acidification, which are respiration associated traits, are suitable for high-throughput screening as demonstrated by the screening of 8000 Lactococcus lactis insertion mutants. Respiration-negative insertion-mutants were found with noxA, bd-type cytochrome and menaquinol biosynthesis gene-disruptions. Phenotypic screening and in silico genome analysis suggest that respiration can be considered characteristic for certain species. We propose that the cyd-genes were present in the common ancestor of lactic acid bacteria, and that multiple gene-loss events best explains the observed distribution of these genes among the species.

  7. Inducible secretion of phytate-degrading enzymes from bacteria ...

    African Journals Online (AJOL)

    More than 320 bacteria were isolated from the soil (Rhizosphere, endophyte, flowers and leaves) of Rosa damascena cv. Taifi and screened for phytase activity. Phytase activity was checked for 24 isolates in Bacillus broth media supplemented with and without rice bran. Twelve (12) isolates were found with detectable ...

  8. Comparative Proteomic Analysis of Desulfotomaculum reducens MI-1: Insights into the Metabolic Versatility of a Gram-positive Sulfate and Metal-reducing Bacterium

    Directory of Open Access Journals (Sweden)

    Anne Elyse Otwell

    2016-02-01

    Full Text Available The proteomes of the metabolically versatile and poorly characterized Gram-positive bacterium Desulfotomaculum reducens MI-1 were compared across four cultivation conditions including sulfate reduction, soluble Fe(III reduction, insoluble Fe(III reduction, and pyruvate fermentation. Collectively across conditions, we observed at high confidence ~38% of genome-encoded proteins. Here, we focus on proteins that display significant differential abundance on conditions tested. To the best of our knowledge, this is the first full-proteome study focused on a Gram-positive organism grown either on sulfate or metal-reducing conditions. Several proteins with uncharacterized function encoded within heterodisulfide reductase (hdr-containing loci were upregulated on either sulfate (Dred_0633-4, Dred_0689-90, and Dred_1325-30 or Fe(III-citrate-reducing conditions (Dred_0432-3 and Dred_1778-84. Two of these hdr-containing loci display homology to recently described flavin-based electron bifurcation (FBEB pathways (Dred_1325-30 and Dred_1778-84. Additionally, we propose that a cluster of proteins, which is homologous to a described FBEB lactate dehydrogenase (LDH complex, is performing lactate oxidation in D. reducens (Dred_0367-9. Analysis of the putative sulfate reduction machinery in D. reducens revealed that most of these proteins are constitutively expressed across cultivation conditions tested. In addition, peptides from the single multiheme c-type cytochrome (MHC in the genome were exclusively observed on the insoluble Fe(III condition, suggesting that this MHC may play a role in reduction of insoluble metals.

  9. Uptake of extracellular DNA: Competence induced pili in natural transformation of Streptococcus pneumoniae

    Science.gov (United States)

    Muschiol, Sandra; Balaban, Murat; Normark, Staffan; Henriques-Normark, Birgitta

    2015-01-01

    Transport of DNA across bacterial membranes involves complex DNA uptake systems. In Gram-positive bacteria, the DNA uptake machinery shares fundamental similarities with type IV pili and type II secretion systems. Although dedicated pilus structures, such as type IV pili in Gram-negative bacteria, are necessary for efficient DNA uptake, the role of similar structures in Gram-positive bacteria is just beginning to emerge. Recently two essentially very different pilus structures composed of the same major pilin protein ComGC were proposed to be involved in transformation of the Gram-positive bacterium Streptococcus pneumoniae – one is a long, thin, type IV pilus-like fiber with DNA binding capacity and the other one is a pilus structure that was thicker, much shorter and not able to bind DNA. Here we discuss how competence induced pili, either by pilus retraction or by a transient pilus-related opening in the cell wall, may mediate DNA uptake in S. pneumoniae. PMID:25640084

  10. Multidrug transporters in lactic acid bacteria

    NARCIS (Netherlands)

    Mazurkiewicz, P; Sakamoto, K; Poelarends, GJ; Konings, WN

    Gram-positive lactic acid bacteria possess several Multi-Drug Resistance systems (MDRs) that excrete out of the cell a wide variety of mainly cationic lipophilic cytotoxic compounds as well as many clinically relevant antibiotics. These MDRs are either proton/drug antiporters belonging to the major

  11. The effects of deuterium-depleted water on bacteria

    International Nuclear Information System (INIS)

    Butnaru, Gallia; Jurca, Elena M.; Titescu, Gh.; Stefanescu, I.

    2000-01-01

    Due to their adaptability the bacteria are ubiquitous, occurring in a large variety of habitats. Most of them are saprotrophs or parasites. Bacteria are agents causing many diseases in animals and humans. The main purpose of this work was to reveal the deuterium-depleted water bactericidal effect. Nonpathogenic Gram-positive (Bacillus subtilis and Bacillus cereus) and pathogenic Gram-negative (Agrobacterium tumefaciens, Erwinia amylovora and Escherichia coli) bacteria were used. The variant deuterium depleted (DDW) eater was compared with distilled water eater one. The diffusometric method was found the proper way of investigation. The bacteria culture was developed in Petri dishes (diam = 70 mm) at a temperature of 25 deg. C. After 24 h, 48 h and 72 h the clear area was measured. The clear area was one in which the bacteria were killed. The surface was determined by the area of the small disc on the filter paper. The statistical data were determined by variance analysis. The results pointed out a large response to DDW presence. The data were classified in: 1. without response when no clear area occurred; - 2. with response when a clear area of under 5 mm 2 occurred; - 3. strong response when the clear area was higher than 10 mm 2 . The Gram-positive and Gram-negative bacteria behaviours were not in correlation with the DDW bactericidal effect. The Bacillus cereus and Escherichia coli were scored as without response and we presume that they were very tolerant. No clear area was induced by DDW. Bacillus subtilis and Erwinia amylovora showed weak response. After 24 h the killed bacteria were extended on the same area, namely, 2.89 mm 2 . Even if the DDW effect seems to be small it was significantly in comparison with the control case (s d = 2.78 mm 2 > 0.1). After 48 h and 72 h the clear surface remained the same. The Agrobacterium tumefaciens' response was very strong. The bacteria were killed on 22.50 mm 2 after 24 h and on 26.95 mm 2 after 48 h, being very

  12. Transepithelial activation of human leukocytes by probiotics and commensal bacteria: role of Enterobacteriaceae-type endotoxin

    DEFF Research Database (Denmark)

    Bäuerlein, A.; Ackermann, S.; Parlesak, Alexandr

    2009-01-01

    The goal of the current study was to clarify whether commercially available probiotics induce greater trans-epithelial activation of human leukocytes than do commensal, food-derived and pathogenic bacteria and to identify the compounds responsible for this activation. Eleven different bacterial...... Escherichia coli K12, probiotic E. coli Nissle, EPEC) induced basolateral production of TNF-alpha, IFN-gamma, IL 6, 8, and 10. Gram-positive probiotics (Lactobacillus spp. and Bifidobacterium spp.) had virtually no effect. In addition, commensals (Enterococcus faecalis, Bacteroides vulgatus) and food...... (polymyxin, colistin) completely abrogated transepithelial activation of leukocytes. Enterobacteriaceae-type endotoxin is a crucial factor in transepithelial stimulation of leukocytes, regardless of whether it is produced by probiotics or other bacteria. Hence, transepithelial stimulation ofleukocytes...

  13. Transepithelial activation of human leukocytes by probiotics and commensal bacteria: Role of Enterobacteriaceae-type endotoxin

    DEFF Research Database (Denmark)

    Baeuerlein, Annette; Ackermann, Stefanie; Parlesak, Alexandr

    2009-01-01

    The goal of the current study was to clarify whether commercially available probiotics induce greater trans-epithelial activation of human leukocytes than do commensal, food-derived and pathogenic bacteria and to identify the compounds responsible for this activation. Eleven different bacterial...... Escherichia coli K12, probiotic E. coli Nissle, EPEC) induced basolateral production of TNF-alpha, IFN-gamma, IL 6, 8, and 10. Gram-positive probiotics (Lactobacillus spp. and Bifidobacterium spp.) had virtually no effect. In addition, commensals (Enterococcus faecalis, Bacteroides vulgatus) and food...... (polymyxin, colistin) completely abrogated transepithelial activation of leukocytes. Enterobacteriaceae-type endotoxin is a crucial factor in transepithelial stimulation of leukocytes, regardless of whether it is produced by probiotics or other bacteria. Hence, transepithelial stimulation of leukocytes...

  14. UV-induced filamentation in bacteria of the generum Erwinia

    Energy Technology Data Exchange (ETDEWEB)

    Prokulevich, V A; Tomichev, Yu K

    1988-09-01

    It is experimentally shown that cells of 56 pectolytic Erwinia strains isolated at different tomus in different states from various natural sources are converted into filaments under UV-light effect in relatively low doses which allows one to refer them to natural Fil/sup +/ - organisms. Ability to filamentation in Erwinia bacterium correlates with secretion process to the environment of pectolytic enzymes. Bacteria of 9 E.herbicola strains investigated (without pectatlyase secretion) after irradiation do not form stretched cells. Based on the results obtained a conclusion is drawn that increased ENA49 E.chrysanthemic cell sensitivity to UV light results from its natural defect in the system, providing for cell division processes like the one revealed in E.CoLiB and Lon/sup -/ - mutants of E.Coli K-12.

  15. In vitro activities of the new semisynthetic glycopeptide telavancin (TD-6424), vancomycin, daptomycin, linezolid, and four comparator agents against anaerobic gram-positive species and Corynebacterium spp.

    Science.gov (United States)

    Goldstein, Ellie J C; Citron, Diane M; Merriam, C Vreni; Warren, Yumi A; Tyrrell, Kerin L; Fernandez, Helen T

    2004-06-01

    Telavancin is a new semisynthetic glycopeptide anti-infective with multiple mechanisms of action, including inhibition of bacterial membrane phospholipid synthesis and inhibition of bacterial cell wall synthesis. We determined the in vitro activities of telavancin, vancomycin, daptomycin, linezolid, quinupristin-dalfopristin, imipenem, piperacillin-tazobactam, and ampicillin against 268 clinical isolates of anaerobic gram-positive organisms and 31 Corynebacterium strains using agar dilution methods according to National Committee for Clinical Laboratory Standards procedures. Plates with daptomycin were supplemented with Ca(2+) to 50 mg/liter. The MICs at which 90% of isolates tested were inhibited (MIC(90)s) for telavancin and vancomycin were as follows: Actinomyces spp. (n = 45), 0.25 and 1 microg/ml, respectively; Clostridium difficile (n = 14), 0.25 and 1 microg/ml, respectively; Clostridium ramosum (n = 16), 1 and 4 microg/ml, respectively; Clostridium innocuum (n = 15), 4 and 16 microg/ml, respectively; Clostridium clostridioforme (n = 15), 8 and 1 microg/ml, respectively; Eubacterium group (n = 33), 0.25 and 2 microg/ml, respectively; Lactobacillus spp. (n = 26), 0.5 and 4 microg/ml, respectively; Propionibacterium spp. (n = 34), 0.125 and 0.5 microg/ml, respectively; Peptostreptococcus spp. (n = 52), 0.125 and 0.5 microg/ml, respectively; and Corynebacterium spp. (n = 31), 0.03 and 0.5 microg/ml, respectively. The activity of TD-6424 was similar to that of quinupristin-dalfopristin for most strains except C. clostridioforme and Lactobacillus casei, where quinupristin-dalfopristin was three- to fivefold more active. Daptomycin had decreased activity (MIC > 4 microg/ml) against 14 strains of Actinomyces spp. and all C. ramosum, Eubacterium lentum, and Lactobacillus plantarum strains. Linezolid showed decreased activity (MIC > 4 microg/ml) against C. ramosum, two strains of C. difficile, and 15 strains of Lactobacillus spp. Imipenem and piperacillin

  16. Bactericidal effects of antibiotics on slowly growing and nongrowing bacteria.

    OpenAIRE

    Eng, R H; Padberg, F T; Smith, S M; Tan, E N; Cherubin, C E

    1991-01-01

    Antimicrobial agents are most often tested against bacteria in the log phase of multiplication to produce the maximum bactericidal effect. In an infection, bacteria may multiply less optimally. We examined the effects of several classes of antimicrobial agents to determine their actions on gram-positive and gram-negative bacteria during nongrowing and slowly growing phases. Only ciprofloxacin and ofloxacin exhibited bactericidal activity against nongrowing gram-negative bacteria, and no antib...

  17. Use of magnetic beads for Gram staining of bacteria in aqueous suspension.

    Science.gov (United States)

    Yazdankhah, S P; Sørum, H; Larsen, H J; Gogstad, G

    2001-12-01

    A Gram staining technique was developed using monodisperse magnetic beads in concentrating bacteria in suspension for downstream application. The technique does not require heat fixation of organisms, electrical power, or a microscope. Gram-negative and Gram-positive bacteria were identified macroscopically based on the colour of the suspension. The bacteria concentrated on magnetic beads may also be identified microscopically.

  18. Phage-inducible chromosomal islands are ubiquitous within the bacterial universe.

    Science.gov (United States)

    Fillol-Salom, Alfred; Martínez-Rubio, Roser; Abdulrahman, Rezheen F; Chen, John; Davies, Robert; Penadés, José R

    2018-06-06

    Phage-inducible chromosomal islands (PICIs) are a recently discovered family of pathogenicity islands that contribute substantively to horizontal gene transfer, host adaptation and virulence in Gram-positive cocci. Here we report that similar elements also occur widely in Gram-negative bacteria. As with the PICIs from Gram-positive cocci, their uniqueness is defined by a constellation of features: unique and specific attachment sites, exclusive PICI genes, a phage-dependent mechanism of induction, conserved replication origin organization, convergent mechanisms of phage interference, and specific packaging of PICI DNA into phage-like infectious particles, resulting in very high transfer frequencies. We suggest that the PICIs represent two or more distinct lineages, have spread widely throughout the bacterial world, and have diverged much more slowly than their host organisms or their prophage cousins. Overall, these findings represent the discovery of a universal class of mobile genetic elements.

  19. Use of tuf as a target for sequence-based identification of Gram-positive cocci of the genus Enterococcus, Streptococcus, coagulase-negative Staphylococcus, and Lactococcus

    Directory of Open Access Journals (Sweden)

    Li Xuerui

    2012-11-01

    Full Text Available Abstract Background Accurate identification of isolates belonging to genus Enterococcus, Streptococcus, coagulase-negative Staphylococcus, and Lactococcus at the species level is necessary to provide a better understanding of their pathogenic potential, to aid in making clinical decisions, and to conduct epidemiologic investigations,especially when large blind samples must be analyzed. It is useful to simultaneously identify species in different genera using a single primer pair. Methods We developed a primer pair based on the tuf gene (encoding elongation factor sequence to identify 56 Gram-positive cocci isolates. Results The target sequences were amplified from all 56 samples. The sequencing results and the phylogenetic tree derived from the partial tuf gene sequences identified the isolates as three enterococcal species, two lactococcal species, two staphylococcal species, and six streptococcal species, as well as eight isolates that were novel species of the genus Streptococcus. Partial gene sequence analysis of the sodA, dnaK, and 16S RNA genes confirmed the results obtained by tuf gene sequencing. Conclusion Based on the uniform amplification of the tuf gene from all samples and the ability to identify all isolates at both the genus and species levels, we conclude that the primer pair developed in this research provides a powerful tool for identifying these organisms in clinical laboratories where large blind samples are used.

  20. A thiol-disulfide oxidoreductase of the Gram-positive pathogen Corynebacterium diphtheriae is essential for viability, pilus assembly, toxin production and virulence.

    Science.gov (United States)

    Reardon-Robinson, Melissa E; Osipiuk, Jerzy; Jooya, Neda; Chang, Chungyu; Joachimiak, Andrzej; Das, Asis; Ton-That, Hung

    2015-12-01

    The Gram-positive pathogen Corynebacterium diphtheriae exports through the Sec apparatus many extracellular proteins that include the key virulence factors diphtheria toxin and the adhesive pili. How these proteins attain their native conformations after translocation as unfolded precursors remains elusive. The fact that the majority of these exported proteins contain multiple cysteine residues and that several membrane-bound oxidoreductases are encoded in the corynebacterial genome suggests the existence of an oxidative protein-folding pathway in this organism. Here we show that the shaft pilin SpaA harbors a disulfide bond in vivo and alanine substitution of these cysteines abrogates SpaA polymerization and leads to the secretion of degraded SpaA peptides. We then identified a thiol-disulfide oxidoreductase (MdbA), whose structure exhibits a conserved thioredoxin-like domain with a CPHC active site. Remarkably, deletion of mdbA results in a severe temperature-sensitive cell division phenotype. This mutant also fails to assemble pilus structures and is greatly defective in toxin production. Consistent with these defects, the ΔmdbA mutant is attenuated in a guinea pig model of diphtheritic toxemia. Given its diverse cellular functions in cell division, pilus assembly and toxin production, we propose that MdbA is a component of the general oxidative folding machine in C. diphtheriae. © 2015 John Wiley & Sons Ltd.

  1. Sediminibacillus massiliensis sp. nov., a moderately halophilic, Gram-positive bacterium isolated from a stool sample of a young Senegalese man.

    Science.gov (United States)

    Senghor, Bruno; Bassène, Hubert; Khelaifia, Saber; Robert, Catherine; Fournier, Pierre-Edouard; Ruimy, Raymond; Sokhna, Cheikh; Raoult, Didier; Lagier, Jean-Christophe

    2018-07-01

    A Gram-positive, moderately halophilic bacterium, referred to as strain Marseille-P3518 T , was isolated from a stool sample with 2% NaCl concentration from a healthy 15-year-old male living in Dielmo, a village in Senegal. Cells are aerobic, rod-shaped and motile and display endospore formation. Strain Marseille-P3518 T can grow in a medium with 0-20% (w/v) sodium chloride (optimally at 5-7.5% w/v). The major fatty acids were 12-methyl-tetradecanoic acid (45.8%), 13-methyl-tetradecanoic acid (26.9%) and 12-methyl-tridecanoic acid (12.8%). The genome is 4,347,479 bp long with 42.1% G+C content. It contains 4282 protein-coding and 107 RNA genes. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain Marseille-P3518 T is a member of the Bacillaceae family and is closely related to Sediminibacillus albus (97.4% gene sequence similarity). Strain Marseille-P3518 T was clearly differentiated from its phylogenetic neighbors on the basis of phenotypic and genotypic features. Strain Marseille-P3518 T is, therefore, considered to be a novel representative of the genus Sediminibacillus, for which the name Sediminibacillus massiliensis sp. nov. is proposed, and the type strain is Marseille-P3518 T (CSUR P3518T, DSM69894).

  2. Pili-Induced Clustering of N. gonorrhoeae Bacteria.

    Directory of Open Access Journals (Sweden)

    Johannes Taktikos

    Full Text Available Type IV pili (Tfp are prokaryotic retractable appendages known to mediate surface attachment, motility, and subsequent clustering of cells. Tfp are the main means of motility for Neisseria gonorrhoeae, the causative agent of gonorrhea. Tfp are also involved in formation of the microcolonies, which play a crucial role in the progression of the disease. While motility of individual cells is relatively well understood, little is known about the dynamics of N. gonorrhoeae aggregation. We investigate how individual N. gonorrhoeae cells, initially uniformly dispersed on flat plastic or glass surfaces, agglomerate into spherical microcolonies within hours. We quantify the clustering process by measuring the area fraction covered by the cells, number of cell aggregates, and their average size as a function of time. We observe that the microcolonies are also able to move but their mobility rapidly vanishes as the size of the colony increases. After a certain critical size they become immobile. We propose a simple theoretical model which assumes a pili-pili interaction of cells as the main clustering mechanism. Numerical simulations of the model quantitatively reproduce the experimental data on clustering and thus suggest that the agglomeration process can be entirely explained by the Tfp-mediated interactions. In agreement with this hypothesis mutants lacking pili are not able to form colonies. Moreover, cells with deficient quorum sensing mechanism show similar aggregation as the wild-type bacteria. Therefore, our results demonstrate that pili provide an essential mechanism for colony formation, while additional chemical cues, for example quorum sensing, might be of secondary importance.

  3. Gram negative bacteria and contact lens induced acute red eye

    Directory of Open Access Journals (Sweden)

    Sankaridurg Padmaja

    1996-01-01

    Full Text Available Two patients using hydrogel contact lenses on a daily wear schedule slept overnight with the lenses and woke up with a Contact Lens Induced Acute Red Eye (CLARE. The contact lenses recovered aseptically at the time of the event grew significant colonies of Pseudomonas aeruginosa and Aeromonas hydrophila in patient A and Pseudomonas aeruginosa and Serratia liquefaciens from patient B. Similar organisams from the contact lenses were recovered from the lens case and lens care solutions of patient B. In both the patients the condition resolved on discontinuation of lens wear. Patient compliance as a requirement for successful contact lens wear is highlighted with the illustration of these cases.

  4. Bacteria-induced histamine release from human bronchoalveolar cells and blood leukocytes

    DEFF Research Database (Denmark)

    Clementsen, P; Milman, N; Struve-Christensen, E

    1991-01-01

    23187 resulted in histamine release. S. aureus-induced histamine release from basophils was examined in leukocyte suspensions obtained from the same individuals, and in all experiments release was found. The dose-response curves were similar to those obtained with BAL cells. The bacteria...

  5. Silver enhances antibiotic activity against gram-negative bacteria.

    Science.gov (United States)

    Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

    2013-06-19

    A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

  6. Antibiotic Susceptibility Pattern of Gram-positive Cocci Cultured from Patients in Three University Hospitals in Tehran, Iran during 2001-2005

    Directory of Open Access Journals (Sweden)

    Aligholi Marzieh

    2009-10-01

    Full Text Available Bacterial resistance to antibiotics is a serious problem and is increasing in prevalence world-wide at an alarming rate. The antimicrobial susceptibility patterns of 1897 gram-positive bacterial Isolates were evaluated. The minimum inhibitory concentration (MIC of isolates which comprised Staphylococcus aureus (927 isolates, coagulase-negative staphylococci (CNS; 425 isolates, Enterococcus faecalis (320 isolates, Enterococcus faecium (157 isolates, and pneumococci (50 isolates collected from 3 teaching hospitals in Tehran were determined by agar dilution method according to Clinical and Laboratory Standards Institute (CLSI guidelines. The presence of mecA gene was investigated in methicillin-resistant staphylococci by PCR method and vanA and vanB genes were targeted in enterococcal isolates by Multiplex PCR method. The resistance rate to methicillin among S. aureus and CNS isolates were 33% and 49%, respectively. All S. aureus isolates were susceptible to vancomycin .The lowest rate of resistance in all S. aureus isolates was found for rifampicin (<4%. The vancomycin resistance rate in enterococci isolates was 11% which was more frequent among E. faecium (19% than E. faecalis (4%, all resistant isolates carrying vanA. High-level resistance to gentamicin and streptomycin, were detected in 47% and 87% of enterococcal isolates respectively. The rate of penicillin resistance in pneumococci was 3% and about 27% of isolates had reduced susceptibility to penicillin. The prevalence of erythromycin resistant among pneumococci was 58%. All pneumococcal isolates were susceptible to ceftriaxone, rifampicin and vancomycin. Our data highlight the importance of access to updated bacterial susceptibility data regarding commonly prescribed agents for clinicians in Iran.

  7. Electron Transport Chain Is Biochemically Linked to Pilus Assembly Required for Polymicrobial Interactions and Biofilm Formation in the Gram-Positive Actinobacterium Actinomyces oris

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    Belkys C. Sanchez

    2017-06-01

    Full Text Available The Gram-positive actinobacteria Actinomyces spp. are key colonizers in the development of oral biofilms due to the inherent ability of Actinomyces to adhere to receptor polysaccharides on the surface of oral streptococci and host cells. This receptor-dependent bacterial interaction, or coaggregation, requires a unique sortase-catalyzed pilus consisting of the pilus shaft FimA and the coaggregation factor CafA forming the pilus tip. While the essential role of the sortase machine SrtC2 in pilus assembly, biofilm formation, and coaggregation has been established, little is known about trans-acting factors contributing to these processes. We report here a large-scale Tn5 transposon screen for mutants defective in Actinomyces oris coaggregation with Streptococcus oralis. We obtained 33 independent clones, 13 of which completely failed to aggregate with S. oralis, and the remainder of which exhibited a range of phenotypes from severely to weakly defective coaggregation. The former had Tn5 insertions in fimA, cafA, or srtC2, as expected; the latter were mapped to genes coding for uncharacterized proteins and various nuo genes encoding the NADH dehydrogenase subunits. Electron microscopy and biochemical analyses of mutants with nonpolar deletions of nuo genes and ubiE, a menaquinone C-methyltransferase-encoding gene downstream of the nuo locus, confirmed the pilus and coaggregation defects. Both nuoA and ubiE mutants were defective in oxidation of MdbA, the major oxidoreductase required for oxidative folding of pilus proteins. Furthermore, supplementation of the ubiE mutant with exogenous menaquinone-4 rescued the cell growth and pilus defects. Altogether, we propose that the A. oris electron transport chain is biochemically linked to pilus assembly via oxidative protein folding.

  8. Molecular evolution of the nif gene cluster carrying nifI1 and nifI2 genes in the Gram-positive phototrophic bacterium Heliobacterium chlorum.

    Science.gov (United States)

    Enkh-Amgalan, Jigjiddorj; Kawasaki, Hiroko; Seki, Tatsuji

    2006-01-01

    A major nif cluster was detected in the strictly anaerobic, Gram-positive phototrophic bacterium Heliobacterium chlorum. The cluster consisted of 11 genes arranged within a 10 kb region in the order nifI1, nifI2, nifH, nifD, nifK, nifE, nifN, nifX, fdx, nifB and nifV. The phylogenetic position of Hbt. chlorum was the same in the NifH, NifD, NifK, NifE and NifN trees; Hbt. chlorum formed a cluster with Desulfitobacterium hafniense, the closest neighbour of heliobacteria based on the 16S rRNA phylogeny, and two species of the genus Geobacter belonging to the Deltaproteobacteria. Two nifI genes, known to occur in the nif clusters of methanogenic archaea between nifH and nifD, were found upstream of the nifH gene of Hbt. chlorum. The organization of the nif operon and the phylogeny of individual and concatenated gene products showed that the Hbt. chlorum nif operon carrying nifI genes upstream of the nifH gene was an intermediate between the nif operon with nifI downstream of nifH (group II and III of the nitrogenase classification) and the nif operon lacking nifI (group I). Thus, the phylogenetic position of Hbt. chlorum nitrogenase may reflect an evolutionary stage of a divergence of the two nitrogenase groups, with group I consisting of the aerobic diazotrophs and group II consisting of strictly anaerobic prokaryotes.

  9. Antimicrobial effects of zero-valent iron nanoparticles on gram-positive Bacillus strains and gram-negative Escherichia coli strains

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    Yi-Huang Hsueh

    2017-11-01

    Full Text Available Abstract Background Zero-valent iron nanoparticles (ZVI NPs have been used extensively for the remediation of contaminated soil and groundwater. Owing to their large active surface area, they serve as strong and effective reductants. However, the ecotoxicity and bioavailability of ZVI NPs in diverse ecological media have not been evaluated in detail and most studies have focused on non-nano ZVI or Fe0. In addition, the antimicrobial properties of ZVI NPs have rarely been investigated, and the underlying mechanism of their toxicity remains unknown. Results In the present study, we demonstrate that ZVI NPs exhibited significant toxicity at 1000 ppm against two distinct gram-positive bacterial strains (Bacillus subtilis 3610 and Bacillus thuringiensis 407 but not against two gram-negative strains (Escherichia coli K12 and ATCC11634. Specifically, ZVI NPs caused at least a 4-log and 1-log reductions in cell numbers, respectively, in the two Bacillus strains, whereas no change was detected in the two E. coli strains. X-ray photoelectron spectroscopy, X-ray absorption near-edge, and extended X-ray absorption fine structure spectra confirmed that Bacillus cells exposed to ZVI NPs contained mostly Fe2O3 with some detectable FeS. This finding indicated that Fe0 nanoparticles penetrated the bacterial cells, where they were subsequently oxidized to Fe2O3 and FeS. RedoxSensor analysis and propidium iodide (PI staining showed decreased reductase activity and increased PI in both Bacillus strains treated with a high (1000 ppm concentration of ZVI NPs. Conclusion Taken together, these data show that the toxicity of ZVI NPs was derived from their oxidative properties, which may increase the levels of reactive oxygen species and lead to cell death.

  10. A Transient Exposure to Symbiosis-Competent Bacteria Induces Light Organ Morphogenesis in the Host Squid.

    Science.gov (United States)

    Doino, J A; McFall-Ngai, M J

    1995-12-01

    Recent studies of the symbiotic association between the Hawaiian sepiolid squid Euprymna scolopes and the luminous bacterium Vibrio fischeri have shown that colonization of juvenile squid with symbiosis-competent bacteria induces morphogenetic changes of the light organ. These changes occur over a 4-day period and include cell death and tissue regression of the external ciliated epithelium. In the absence of bacterial colonization, morphogenesis does not occur. To determine whether the bacteria must be present throughout the morphogenetic process, we used the antibiotic chloramphenicol to clear the light organ of bacteria at various times during the initial colonization. We provide evidence in this study that a transient, 12-hour exposure to symbiosis-competent bacteria is necessary and sufficient to induce tissue regression in the light organ over the next several days. Further, we show that successful entrance into the light organ is necessary to induce morphogenesis, suggesting that induction results from bacterial interaction with internal crypt cells and not with the external ciliated epithelium. Finally, no difference in development was observed when the light organ was colonized by a mutant strain of V. fischeri that did not produce autoinducer, a potential light organ morphogen.

  11. Contributions of gut bacteria to Bacillus thuringiensis-induced mortality vary across a range of Lepidoptera

    Directory of Open Access Journals (Sweden)

    Holt Jonathan

    2009-03-01

    treatment significantly increased mortality of Pectinophora gossypiella (Saunders, which was also the only species with detectable gut bacteria that lacked a Gram-negative component. Further, mortality of P. gossypiella larvae reared on diet amended with B. thuringiensis toxin and Enterobacter sp. NAB3 was generally faster than with B. thuringiensis toxin alone. Conclusion This study demonstrates that in some larval species, indigenous gut bacteria contribute to B. thuringiensis susceptibility. Moreover, the contribution of enteric bacteria to host mortality suggests that perturbations caused by toxin feeding induce otherwise benign gut bacteria to exert pathogenic effects. The interaction between B. thuringiensis and the gut microbiota of Lepidoptera may provide a useful model with which to identify the factors involved in such transitions.

  12. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Analysis of Gram-Positive, Catalase-Negative Cocci Not Belonging to the Streptococcus or Enterococcus Genus and Benefits of Database Extension

    DEFF Research Database (Denmark)

    Christensen, Jens Jørgen; Dargis, Rimtas; Hammer, Monja

    2012-01-01

    Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry with a Bruker Daltonics microflex LT system was applied to 90 well-characterized catalase-negative, Gram-positive cocci not belonging to the streptococci or enterococci. Biotyper version 2.0.43.1 software...

  13. Radiation induced damage to the lipid contents of bacteria and cultured mammalian cells

    International Nuclear Information System (INIS)

    Gholipour Khalili, K.

    1993-01-01

    In this study, exponentially growing phase of E. Coli. K12-N167 and cultured mouse leukemic L5178Y were used to study the effect of gamma irradiation on phospholipid contents. Following irradiation, both bacteria and cultured cells were incubated with either 14 C or 32 P labelled precursors for periods of cell division time. Phospholipid composition and their contents were detected in both the bacteria and cultured cells by using liquid scintillation counting and autoradiography methods. In contrast, as radiation dose increased, the Phospholipid contents were decreased in the both bacteria and cultured cells. It was concluded that the changes of phospholipid contents may result to altered activities of phospholipid pathway enzymes damaged by a radiation dose. The results of this investigation would be helpful in control of induced radiation damages in cell killings in radiation workers and radiation treatment of human cancer in the clinics. (author). 35 refs, 3 figs, 4 tabs

  14. Exploring bacteria-induced growth and morphogenesis in the green macroalga order Ulvales (Chlorophyta

    Directory of Open Access Journals (Sweden)

    Thomas eWichard

    2015-03-01

    Full Text Available Green macroalgae, such as Ulvales, lose their typical morphology completely when grown under axenic conditions or in the absence of the appropriate microbiome. As a result, slow growing aberrant phenotypes or even callus-like morphotypes are observed in Ulvales. The cross-kingdom interactions between marine algae and microorganisms are hence not only restricted by the exchange of macronutrients, including vitamins and nutrients, but also by infochemicals such as bacterial morphogenetic compounds. The latter are a fundamental trait mediating the mutualism within the chemosphere where the organisms interact with each other via compounds in their surroundings.Approximately 60 years ago, pilot studies demonstrated that certain bacteria promote growth, whereas other bacteria induce morphogenesis; this is particularly true for the order of Ulvales. However, only slow progress was made towards the underlying mechanism due to the complexity of, for example, algal cultivation techniques, and the lack of standardized experiments in the laboratory.A breakthrough in this research was the discovery of the morphogenetic compound thallusin, which was isolated from an epiphytic bacterium and induces normal germination and restores the foliaceous morphotypes of Monostroma. Owing to the low concentration, the purification and structure elucidation of highly biologically active morphogenetic compounds is still challenging. Recently, it was found that only the combination of two specific bacteria from the Rhodobacteraceae and Flavobacteriaceae can completely recover the growth and morphogenesis of axenic Ulva mutabilis cultures forming a symbiotic tripartite community by chemical communication.This review combines literature detailing evidence of bacteria-induced morphogenesis in Ulvales. A set of standardized experimental approaches is further proposed for the preparation of axenic algal tissues, bacteria isolation, co-cultivation experiments, and the analysis of

  15. Exploring bacteria-induced growth and morphogenesis in the green macroalga order Ulvales (Chlorophyta)

    Science.gov (United States)

    Wichard, Thomas

    2015-01-01

    Green macroalgae, such as Ulvales, lose their typical morphology completely when grown under axenic conditions or in the absence of the appropriate microbiome. As a result, slow growing aberrant phenotypes or even callus-like morphotypes are observed in Ulvales. The cross-kingdom interactions between marine algae and microorganisms are hence not only restricted by the exchange of macronutrients, including vitamins and nutrients, but also by infochemicals such as bacterial morphogenetic compounds. The latter are a fundamental trait mediating the mutualism within the chemosphere where the organisms interact with each other via compounds in their surroundings. Approximately 60 years ago, pilot studies demonstrated that certain bacteria promote growth, whereas other bacteria induce morphogenesis; this is particularly true for the order of Ulvales. However, only slow progress was made towards the underlying mechanism due to the complexity of, for example, algal cultivation techniques, and the lack of standardized experiments in the laboratory. A breakthrough in this research was the discovery of the morphogenetic compound thallusin, which was isolated from an epiphytic bacterium and induces normal germination restoring the foliaceous morphotypes of Monostroma. Owing to the low concentration, the purification and structure elucidation of highly biologically active morphogenetic compounds are still challenging. Recently, it was found that only the combination of two specific bacteria from the Rhodobacteraceae and Flavobacteriaceae can completely recover the growth and morphogenesis of axenic Ulva mutabilis cultures forming a symbiotic tripartite community by chemical communication. This review combines literature detailing evidences of bacteria-induced morphogenesis in Ulvales. A set of standardized experimental approaches is further proposed for the preparation of axenic algal tissues, bacteria isolation, co-cultivation experiments, and the analysis of the chemosphere

  16. Clinical significance of coryneform Gram-positive rods from blood identified by MALDI-TOF mass spectrometry and their susceptibility profiles - a retrospective chart review.

    Science.gov (United States)

    Mushtaq, Ammara; Chen, Derrick J; Strand, Gregory J; Dylla, Brenda L; Cole, Nicolynn C; Mandrekar, Jayawant; Patel, Robin

    2016-07-01

    With the advent of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), most Gram-positive rods (GPRs) are readily identified; however, their clinical relevance in blood cultures remains unclear. Herein, we assessed the clinical significance of GPRs isolated from blood and identified in the era of MALDI-TOF MS. A retrospective chart review of patients presenting to the Mayo Clinic, Rochester, MN, from January 1, 2013, to October 13, 2015, was performed. Any episode of a positive blood culture for a GPR was included. We assessed the number of bottles positive for a given isolate, time to positivity of blood cultures, patient age, medical history, interpretation of culture results by the healthcare team and whether infectious diseases consultation was obtained. We also evaluated the susceptibility profiles of a larger collection of GPRs tested in the clinical microbiology laboratory of the Mayo Clinic, Rochester, MN from January 1, 2013, to October 31, 2015. There were a total of 246 GPRs isolated from the blood of 181 patients during the study period. 56% (n = 101) were deemed contaminants by the healthcare team and were not treated; 33% (n = 59) were clinically determined to represent true bacteremia and were treated; and 8% (n = 14) were considered of uncertain significance, with patients prescribed treatment regardless. Patient characteristics associated with an isolate being treated on univariate analysis included younger age (P = 0.02), identification to the species level (P = 0.02), higher number of positive blood culture sets (P < 0.0001), lower time to positivity (P < 0.0001), immunosuppression (P = 0.03), and recommendation made by an infectious disease consultant (P = 0.0005). On multivariable analysis, infectious diseases consultation (P = 0.03), higher number of positive blood culture sets (P = 0.0005) and lower time to positivity (P = 0.03) were associated with an isolate being treated. 100, 83, 48 and 34% of GPRs

  17. Functional validation of putative toxin-antitoxin genes from the Gram-positive pathogen Streptococcus pneumoniae: phd-doc is the fourth bona-fide operon.

    Science.gov (United States)

    Chan, Wai Ting; Yeo, Chew Chieng; Sadowy, Ewa; Espinosa, Manuel

    2014-01-01

    Bacterial toxin-antitoxin (TAs) loci usually consist of two genes organized as an operon, where their products are bound together and inert under normal conditions. However, under stressful circumstances the antitoxin, which is more labile, will be degraded more rapidly, thereby unleashing its cognate toxin to act on the cell. This, in turn, causes cell stasis or cell death, depending on the type of TAs and/or time of toxin exposure. Previously based on in silico analyses, we proposed that Streptococcus pneumoniae, a pathogenic Gram-positive bacterium, may harbor between 4 and 10 putative TA loci depending on the strains. Here we have chosen the pneumococcal strain Hungary(19A)-6 which contains all possible 10 TA loci. In addition to the three well-characterized operons, namely relBE2, yefM-yoeB, and pezAT, we show here the functionality of a fourth operon that encodes the pneumococcal equivalent of the phd-doc TA. Transcriptional fusions with gene encoding Green Fluorescent Protein showed that the promoter was slightly repressed by the Phd antitoxin, and exhibited almost background values when both Phd-Doc were expressed together. These findings demonstrate that phd-doc shows the negative self-regulatory features typical for an authentic TA. Further, we also show that the previously proposed TAs XreA-Ant and Bro-XreB, although they exhibit a genetic organization resembling those of typical TAs, did not appear to confer a functional behavior corresponding to bona fide TAs. In addition, we have also discovered new interesting bioinformatics results for the known pneumococcal TAs RelBE2 and PezAT. A global analysis of the four identified toxins-antitoxins in the pneumococcal genomes (PezAT, RelBE2, YefM-YoeB, and Phd-Doc) showed that RelBE2 and Phd-Doc are the most conserved ones. Further, there was good correlation among TA types, clonal complexes and sequence types in the 48 pneumococcal strains analyzed.

  18. Campylobacter jejuni induces transcytosis of commensal bacteria across the intestinal epithelium through M-like cells

    Science.gov (United States)

    2010-01-01

    Background Recent epidemiological analyses have implicated acute Campylobacter enteritis as a factor that may incite or exacerbate inflammatory bowel disease (IBD) in susceptible individuals. We have demonstrated previously that C. jejuni disrupts the intestinal barrier function by rapidly inducing epithelial translocation of non-invasive commensal bacteria via a transcellular lipid raft-mediated mechanism ('transcytosis'). To further characterize this mechanism, the aim of this current study was to elucidate whether C. jejuni utilizes M cells to facilitate transcytosis of commensal intestinal bacteria. Results C. jejuni induced translocation of non-invasive E. coli across confluent Caco-2 epithelial monolayers in the absence of disrupted transepithelial electrical resistance or increased permeability to a 3 kDa dextran probe. C. jejuni-infected monolayers displayed increased numbers of cells expressing the M cell-specific marker, galectin-9, reduced numbers of enterocytes that stained with the absorptive enterocyte marker, Ulex europaeus agglutinin-1, and reduced activities of enzymes typically associated with absorptive enterocytes (namely alkaline phosphatase, lactase, and sucrase). Furthermore, in Campylobacter-infected monolayers, E. coli were observed to be internalized specifically within epithelial cells displaying M-like cell characteristics. Conclusion These data indicate that C. jejuni may utilize M cells to promote transcytosis of non-invasive bacteria across the intact intestinal epithelial barrier. This mechanism may contribute to the inflammatory immune responses against commensal intestinal bacteria commonly observed in IBD patients. PMID:21040540

  19. Campylobacter jejuni induces transcytosis of commensal bacteria across the intestinal epithelium through M-like cells

    Directory of Open Access Journals (Sweden)

    Kalischuk Lisa D

    2010-11-01

    Full Text Available Abstract Background Recent epidemiological analyses have implicated acute Campylobacter enteritis as a factor that may incite or exacerbate inflammatory bowel disease (IBD in susceptible individuals. We have demonstrated previously that C. jejuni disrupts the intestinal barrier function by rapidly inducing epithelial translocation of non-invasive commensal bacteria via a transcellular lipid raft-mediated mechanism ('transcytosis'. To further characterize this mechanism, the aim of this current study was to elucidate whether C. jejuni utilizes M cells to facilitate transcytosis of commensal intestinal bacteria. Results C. jejuni induced translocation of non-invasive E. coli across confluent Caco-2 epithelial monolayers in the absence of disrupted transepithelial electrical resistance or increased permeability to a 3 kDa dextran probe. C. jejuni-infected monolayers displayed increased numbers of cells expressing the M cell-specific marker, galectin-9, reduced numbers of enterocytes that stained with the absorptive enterocyte marker, Ulex europaeus agglutinin-1, and reduced activities of enzymes typically associated with absorptive enterocytes (namely alkaline phosphatase, lactase, and sucrase. Furthermore, in Campylobacter-infected monolayers, E. coli were observed to be internalized specifically within epithelial cells displaying M-like cell characteristics. Conclusion These data indicate that C. jejuni may utilize M cells to promote transcytosis of non-invasive bacteria across the intact intestinal epithelial barrier. This mechanism may contribute to the inflammatory immune responses against commensal intestinal bacteria commonly observed in IBD patients.

  20. Anaerobic bacteria grow within Candida albicans biofilms and induce biofilm formation in suspension cultures.

    Science.gov (United States)

    Fox, Emily P; Cowley, Elise S; Nobile, Clarissa J; Hartooni, Nairi; Newman, Dianne K; Johnson, Alexander D

    2014-10-20

    The human microbiome contains diverse microorganisms, which share and compete for the same environmental niches. A major microbial growth form in the human body is the biofilm state, where tightly packed bacterial, archaeal, and fungal cells must cooperate and/or compete for resources in order to survive. We examined mixed biofilms composed of the major fungal species of the gut microbiome, Candida albicans, and each of five prevalent bacterial gastrointestinal inhabitants: Bacteroides fragilis, Clostridium perfringens, Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis. We observed that biofilms formed by C. albicans provide a hypoxic microenvironment that supports the growth of two anaerobic bacteria, even when cultured in ambient oxic conditions that are normally toxic to the bacteria. We also found that coculture with bacteria in biofilms induces massive gene expression changes in C. albicans, including upregulation of WOR1, which encodes a transcription regulator that controls a phenotypic switch in C. albicans, from the "white" cell type to the "opaque" cell type. Finally, we observed that in suspension cultures, C. perfringens induces aggregation of C. albicans into "mini-biofilms," which allow C. perfringens cells to survive in a normally toxic environment. This work indicates that bacteria and C. albicans interactions modulate the local chemistry of their environment in multiple ways to create niches favorable to their growth and survival. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Impact of bacteria and bacterial components on osteogenic and adipogenic differentiation of adipose-derived mesenchymal stem cells

    International Nuclear Information System (INIS)

    Fiedler, Tomas; Salamon, Achim; Adam, Stefanie; Herzmann, Nicole; Taubenheim, Jan; Peters, Kirsten

    2013-01-01

    Adult mesenchymal stem cells (MSC) are present in several tissues, e.g. bone marrow, heart muscle, brain and subcutaneous adipose tissue. In invasive infections MSC get in contact with bacteria and bacterial components. Not much is known about how bacterial pathogens interact with MSC and how contact to bacteria influences MSC viability and differentiation potential. In this study we investigated the impact of three different wound infection relevant bacteria, Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes, and the cell wall components lipopolysaccharide (LPS; Gram-negative bacteria) and lipoteichoic acid (LTA; Gram-positive bacteria) on viability, proliferation, and osteogenic as well as adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells (adMSC). We show that all three tested species were able to attach to and internalize into adMSC. The heat-inactivated Gram-negative E. coli as well as LPS were able to induce proliferation and osteogenic differentiation but reduce adipogenic differentiation of adMSC. Conspicuously, the heat-inactivated Gram-positive species showed the same effects on proliferation and adipogenic differentiation, while its cell wall component LTA exhibited no significant impact on adMSC. Therefore, our data demonstrate that osteogenic and adipogenic differentiation of adMSC is influenced in an oppositional fashion by bacterial antigens and that MSC-governed regeneration is not necessarily reduced under infectious conditions. - Highlights: • Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli bind to and internalize into adMSC. • Heat-inactivated cells of these bacterial species trigger proliferation of adMSC. • Heat-inactivated E. coli and LPS induce osteogenic differentiation of adMSC. • Heat-inactivated E. coli and LPS reduce adipogenic differentiation of adMSC. • LTA does not influence adipogenic or osteogenic differentiation of adMSC

  2. Impact of bacteria and bacterial components on osteogenic and adipogenic differentiation of adipose-derived mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, Tomas, E-mail: tomas.fiedler@med.uni-rostock.de [Institute for Medical Microbiology, Virology, and Hygiene, Rostock University Medical Center, Schillingallee 70, D-18057 Rostock (Germany); Salamon, Achim; Adam, Stefanie; Herzmann, Nicole [Department of Cell Biology, Rostock University Medical Center, Schillingallee 69, D-18057 Rostock (Germany); Taubenheim, Jan [Institute for Medical Microbiology, Virology, and Hygiene, Rostock University Medical Center, Schillingallee 70, D-18057 Rostock (Germany); Department of Cell Biology, Rostock University Medical Center, Schillingallee 69, D-18057 Rostock (Germany); Peters, Kirsten [Department of Cell Biology, Rostock University Medical Center, Schillingallee 69, D-18057 Rostock (Germany)

    2013-11-01

    Adult mesenchymal stem cells (MSC) are present in several tissues, e.g. bone marrow, heart muscle, brain and subcutaneous adipose tissue. In invasive infections MSC get in contact with bacteria and bacterial components. Not much is known about how bacterial pathogens interact with MSC and how contact to bacteria influences MSC viability and differentiation potential. In this study we investigated the impact of three different wound infection relevant bacteria, Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes, and the cell wall components lipopolysaccharide (LPS; Gram-negative bacteria) and lipoteichoic acid (LTA; Gram-positive bacteria) on viability, proliferation, and osteogenic as well as adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells (adMSC). We show that all three tested species were able to attach to and internalize into adMSC. The heat-inactivated Gram-negative E. coli as well as LPS were able to induce proliferation and osteogenic differentiation but reduce adipogenic differentiation of adMSC. Conspicuously, the heat-inactivated Gram-positive species showed the same effects on proliferation and adipogenic differentiation, while its cell wall component LTA exhibited no significant impact on adMSC. Therefore, our data demonstrate that osteogenic and adipogenic differentiation of adMSC is influenced in an oppositional fashion by bacterial antigens and that MSC-governed regeneration is not necessarily reduced under infectious conditions. - Highlights: • Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli bind to and internalize into adMSC. • Heat-inactivated cells of these bacterial species trigger proliferation of adMSC. • Heat-inactivated E. coli and LPS induce osteogenic differentiation of adMSC. • Heat-inactivated E. coli and LPS reduce adipogenic differentiation of adMSC. • LTA does not influence adipogenic or osteogenic differentiation of adMSC.

  3. Evaluation of the antibacterial potential of Petroselinum crispum and Rosmarinus officinalis against bacteria that cause urinary tract infections

    Directory of Open Access Journals (Sweden)

    Fernanda Villas Boas Petrolini

    2013-09-01

    Full Text Available In this study we evaluated the antibacterial activity of the crude hydroalcoholic extracts, fractions, and compounds of two plant species, namely Rosmarinus officinalis and Petroselinum crispum, against the bacteria that cause urinary tract infection. The microdilution method was used for determination of the minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC. The crude hydroalcoholic extract of R. officinalis displayed in vitro activity against Gram-positive bacteria, with satisfactory MBC for the clinical isolate S. saprophyticus. The fractions and the pure compound rosmarinic acid did not furnish promising results for Gram-negative bacteria, whereas fractions 2, 3, and 4 gave encouraging results for Gram-positive bacteria and acted as bactericide against S. epidermidis as well as E. faecalis (ATCC 29212 and its clinical isolate. R. officinalis led to promising results in the case of Gram-positive bacteria, resulting in a considerable interest in the development of reliable alternatives for the treatment of urinary infections.

  4. Characteristics of airborne bacteria in Mumbai urban environment.

    Science.gov (United States)

    Gangamma, S

    2014-08-01

    Components of biological origin constitute small but a significant proportion of the ambient airborne particulate matter (PM). However, their diversity and role in proinflammatory responses of PM are not well understood. The present study characterizes airborne bacterial species diversity in Mumbai City and elucidates the role of bacterial endotoxin in PM induced proinflammatory response in ex vivo. Airborne bacteria and endotoxin samples were collected during April-May 2010 in Mumbai using six stage microbial impactor and biosampler. The culturable bacterial species concentration was measured and factors influencing the composition were identified by principal component analysis (PCA). The biosampler samples were used to stimulate immune cells in whole blood assay. A total of 28 species belonging to 17 genera were identified. Gram positive and spore forming groups of bacteria dominated the airborne culturable bacterial concentration. The study indicated the dominance of spore forming and human or animal flora derived pathogenic/opportunistic bacteria in the ambient air environment. Pathogenic and opportunistic species of bacteria were also present in the samples. TNF-α induction by PM was reduced (35%) by polymyxin B pretreatment and this result was corroborated with the results of blocking endotoxin receptor cluster differentiation (CD14). The study highlights the importance of airborne biological particles and suggests need of further studies on biological characterization of ambient PM. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Combination of laser-induced breakdown spectroscopy and Raman spectroscopy for multivariate classification of bacteria

    Czech Academy of Sciences Publication Activity Database

    Procházka, D.; Mazura, M.; Samek, Ota; Rebrošová, K.; Pořízka, P.; Klus, J.; Procházková, P.; Novotný, J.; Novotný, K.; Kaiser, J.

    2018-01-01

    Roč. 139 (2018), s. 6-12 ISSN 0584-8547 R&D Projects: GA ČR(CZ) GA15-20645S; GA ČR(CZ) GA16-12477S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : laser-induced breakdown spectroscopy * Raman spectroscopy * chemometrics * bacteria Impact factor: 3.241, year: 2016

  6. Probing the cellular damage in bacteria induced by GaN nanoparticles using confocal laser Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Prasana, E-mail: prasanasahoo@gmail.com [Indira Gandhi Center for Atomic Research, Surface and Nanoscience Division (India); Murthy, P. Sriyutha [Bhabha Atomic Research Centre, Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division (India); Dhara, S., E-mail: dhara@igcar.gov.in [Indira Gandhi Center for Atomic Research, Surface and Nanoscience Division (India); Venugopalan, V. P. [Bhabha Atomic Research Centre, Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division (India); Das, A.; Tyagi, A. K. [Indira Gandhi Center for Atomic Research, Surface and Nanoscience Division (India)

    2013-08-15

    Understanding the mechanism of nanoparticle (NP) induced toxicity in microbes is of potential importance to a variety of disciplines including disease diagnostics, biomedical implants, and environmental analysis. In this context, toxicity to bacterial cells and inhibition of biofilm formation by GaN NPs and their functional derivatives have been investigated against gram positive and gram negative bacterial species down to single cellular level. High levels of inhibition of biofilm formation (>80 %) was observed on treatments with GaN NPs at sub-micro molar concentrations. These results were substantiated with morphological features investigated with field emission scanning electron microscope, and the observed changes in vibrational modes of microbial cells using Raman spectroscopy. Raman spectra provided molecular interpretation of cell damage by registering signatures of molecular vibrations of individual living microbial cells and mapping the interplay of proteins at the cell membrane. As compared to the untreated cells, Raman spectra of NP-treated cells showed an increase in the intensities of characteristic protein bands, which confirmed membrane damage and subsequent release of cellular contents outside the cells. Raman spectral mapping at single cellular level can facilitate understanding of the mechanistic aspect of toxicity of GaN NPs. The effect may be correlated to passive diffusion causing mechanical damage to the membrane or ingress of Ga{sup 3+} (ionic radius {approx}0.076 nm) which can potentially interfere with bacterial metabolism, as it resembles Fe{sup 2+} (ionic radius {approx}0.077 nm), which is essential for energy metabolism.

  7. Probing the cellular damage in bacteria induced by GaN nanoparticles using confocal laser Raman spectroscopy

    International Nuclear Information System (INIS)

    Sahoo, Prasana; Murthy, P. Sriyutha; Dhara, S.; Venugopalan, V. P.; Das, A.; Tyagi, A. K.

    2013-01-01

    Understanding the mechanism of nanoparticle (NP) induced toxicity in microbes is of potential importance to a variety of disciplines including disease diagnostics, biomedical implants, and environmental analysis. In this context, toxicity to bacterial cells and inhibition of biofilm formation by GaN NPs and their functional derivatives have been investigated against gram positive and gram negative bacterial species down to single cellular level. High levels of inhibition of biofilm formation (>80 %) was observed on treatments with GaN NPs at sub-micro molar concentrations. These results were substantiated with morphological features investigated with field emission scanning electron microscope, and the observed changes in vibrational modes of microbial cells using Raman spectroscopy. Raman spectra provided molecular interpretation of cell damage by registering signatures of molecular vibrations of individual living microbial cells and mapping the interplay of proteins at the cell membrane. As compared to the untreated cells, Raman spectra of NP-treated cells showed an increase in the intensities of characteristic protein bands, which confirmed membrane damage and subsequent release of cellular contents outside the cells. Raman spectral mapping at single cellular level can facilitate understanding of the mechanistic aspect of toxicity of GaN NPs. The effect may be correlated to passive diffusion causing mechanical damage to the membrane or ingress of Ga 3+ (ionic radius ∼0.076 nm) which can potentially interfere with bacterial metabolism, as it resembles Fe 2+ (ionic radius ∼0.077 nm), which is essential for energy metabolism

  8. Identification of multidrug-resistant bacteria and Bacillus cereus from ...

    African Journals Online (AJOL)

    However, B. cereus was isolated from the hands of three. HCWs. Table 1 shows species of bacteria isolated from. HCWs and ES in Elkhomes hospital. B. cereus is a Gram-positive spore-forming facultative- anaerobic rod-shaped organism that can be found in different types of soils and widely distributed in the environment.

  9. Analysis of molecular interactions between yoghurt bacteria by an integrated genomics approach

    NARCIS (Netherlands)

    Sieuwerts, S.

    2009-01-01

    The lactic acid bacteria (LAB) are a group of Gram-positive bacteria that ferment sugars such as lactose to produce mainly lactic acid. LAB are a group of industrially important microorganisms that are applied for the production of many fermented foods. These include foods produced with substrates

  10. Isolation of acetogenic bacteria that induce biocorrosion by utilizing metallic iron as the sole electron donor.

    Science.gov (United States)

    Kato, Souichiro; Yumoto, Isao; Kamagata, Yoichi

    2015-01-01

    Corrosion of iron occurring under anoxic conditions, which is termed microbiologically influenced corrosion (MIC) or biocorrosion, is mostly caused by microbial activities. Microbial activity that enhances corrosion via uptake of electrons from metallic iron [Fe(0)] has been regarded as one of the major causative factors. In addition to sulfate-reducing bacteria and methanogenic archaea in marine environments, acetogenic bacteria in freshwater environments have recently been suggested to cause MIC under anoxic conditions. However, no microorganisms that perform acetogenesis-dependent MIC have been isolated or had their MIC-inducing mechanisms characterized. Here, we enriched and isolated acetogenic bacteria that induce iron corrosion by utilizing Fe(0) as the sole electron donor under freshwater, sulfate-free, and anoxic conditions. The enriched communities produced significantly larger amounts of Fe(II) than the abiotic controls and produced acetate coupled with Fe(0) oxidation prior to CH4 production. Microbial community analysis revealed that Sporomusa sp. and Desulfovibrio sp. dominated in the enrichments. Strain GT1, which is closely related to the acetogen Sporomusa sphaeroides, was eventually isolated from the enrichment. Strain GT1 grew acetogenetically with Fe(0) as the sole electron donor and enhanced iron corrosion, which is the first demonstration of MIC mediated by a pure culture of an acetogen. Other well-known acetogenic bacteria, including Sporomusa ovata and Acetobacterium spp., did not grow well on Fe(0). These results indicate that very few species of acetogens have specific mechanisms to efficiently utilize cathodic electrons derived from Fe(0) oxidation and induce iron corrosion. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  11. Wound-induced and bacteria-induced xylem blockage in roses, Astilbe and Viburnum

    NARCIS (Netherlands)

    Loubaud, M.; Doorn, van W.G.

    2004-01-01

    We previously concluded that the xylem blockage that prevents water uptake into several cut flowers is mainly due to the presence of bacteria, whilst in chrysanthemum and Bouvardia we observed a xylem occlusion that was mainly due to a wound-reaction of the plant. We have further tested which of

  12. Capacity of anaerobic bacteria from necrotic dental pulps to induce purulent infections.

    Science.gov (United States)

    Sundqvist, G K; Eckerbom, M I; Larsson, A P; Sjögren, U T

    1979-08-01

    Combinations of bacteria isolated from the root canals of teeth with necrotic pulps and periapical bone destruction were tested for their capacity to induce abscess formation and transmissible infections when inoculated subcutaneously into guinea pigs. Transmissible infections could be induced with combinations obtained from teeth with purulent apical inflammation, but not with combinations from symptomless teeth with chronic apical inflammation. All combinations which gave transmissible infections contained strains of Bacteroides melaninogenicus or B. asaccharolyticus (formerly B. melaninogenicus subsp. asaccharolyticus). The results suggest that purulent inflammation in the apical region in certain cases may be induced by specific combinations of bacteria in the root canal and that the presence of B. melaninogenicus or B. asaccharolyticus in such combinations is essential. However, with one exception, the strains needed the support of additional microorganisms to achieve pathogenicity. The results indicate that Peptostreptococcus micros was also essential. Histological sections of the lesions in the guinea pigs showed that all bacterial combinations induced acute inflammation with an accumulation of polymorphonuclear leukocytes and the formation of an abscess. However, the presence of B. melaninogenicus or B. asaccharolyticus in the combinations resulted in a failure of abscess resolution, with a gradually increaseing accumulation of polymorphonuclear leukocytes.

  13. Gut Microbiota-Induced Immunoglobulin G Controls Systemic Infection by Symbiotic Bacteria and Pathogens

    Science.gov (United States)

    Zeng, Melody Y.; Cisalpino, Daniel; Varadarajan, Saranyaraajan; Hellman, Judith; Warren, H. Shaw; Cascalho, Marilia; Inohara, Naohiro; Núñez, Gabriel

    2016-01-01

    The gut microbiota is compartmentalized in the intestinal lumen and induces local immune responses, but it remains unknown whether the gut microbiota can induce systemic response and contribute to systemic immunity. We report that selective gut symbiotic gram-negative bacteria were able to disseminate systemically to induce immunoglobulin G (IgG) response, which primarily targeted gram-negative bacterial antigens and conferred protection against systemic infections by E. coli and Salmonella by directly coating bacteria to promote killing by phagocytes. T cells and Toll-like receptor 4 on B cells were important in the generation of microbiota-specific IgG. We identified murein lipoprotein (MLP), a highly conserved gram-negative outer membrane protein, as a major antigen that induced systemic IgG homeostatically in both mice and humans. Administration of anti-MLP IgG conferred crucial protection against systemic Salmonella infection. Thus, our findings reveal an important function for the gut microbiota in combating systemic infection through the induction of protective IgG. PMID:26944199

  14. Labelling of bacteria with indium chelates

    International Nuclear Information System (INIS)

    Kleinert, P.; Pfister, W.; Endert, G.; Sproessig, M.

    1985-01-01

    The indium chelates were prepared by reaction of radioactive indiumchloride with 10 μg oxine, 15 μg tropolone and 3 mg acetylacetone, resp. The formed chelates have been incubated with 10 9 germs/ml for 5 minutes, with labelling outputs from 90 to 95%. Both gram-positive (Streptococcus, Staphylococcus) and gram-negative bacteria (Escherichia coli) can be labelled. The reproductive capacity of the bacteria was not impaired. The application of indium labelled bacteria allows to show the distribution of microorganisms within the living organism and to investigate problems of bacterial adherence. (author)

  15. Screening of antibiotic susceptibility to β-lactam-induced elongation of Gram-negative bacteria based on dielectrophoresis.

    Science.gov (United States)

    Chung, Cheng-Che; Cheng, I-Fang; Chen, Hung-Mo; Kan, Heng-Chuan; Yang, Wen-Horng; Chang, Hsien-Chang

    2012-04-03

    We demonstrate a rapid antibiotic susceptibility test (AST) based on the changes in dielectrophoretic (DEP) behaviors related to the β-lactam-induced elongation of Gram-negative bacteria (GNB) on a quadruple electrode array (QEA). The minimum inhibitory concentration (MIC) can be determined within 2 h by observing the changes in the positive-DEP frequency (pdf) and cell length of GNB under the cefazolin (CEZ) treatment. Escherichia coli and Klebsiella pneumoniae and the CEZ are used as the sample bacteria and antibiotic respectively. The bacteria became filamentous due to the inhibition of cell wall synthesis and cell division and cell lysis occurred for the higher antibiotic dose. According to the results, the pdfs of wild type bacteria decrease to hundreds of kHz and the cell length is more than 10 μm when the bacterial growth is inhibited by the CEZ treatment. In addition, the growth of wild type bacteria and drug resistant bacteria differ significantly. There is an obvious decrease in the number of wild type bacteria but not in the number of drug resistant bacteria. Thus, the drug resistance of GNB to β-lactam antibiotics can be rapidly assessed. Furthermore, the MIC determined using dielectrophoresis-based AST (d-AST) was consistent with the results of the broth dilution method. Utilizing this approach could reduce the time needed for bacteria growth from days to hours, help physicians to administer appropriate antibiotic dosages, and reduce the possibility of the occurrence of multidrug resistant (MDR) bacteria.

  16. EFFECT OF SODIUM PHOSPHATES ON SELECTED FOOD GRADE BACTERIA

    Directory of Open Access Journals (Sweden)

    Stanislav Kráčmar

    2011-04-01

    Full Text Available The aim of this study was to examine the inhibitory effect in vitro of selected sodium phosphates (under the corporate names Hexa 68, Hexa 70, Trikrystal, FST, Pyro 52, KPS, Didi on selected gram-positive and gram-negative bacteria. Seven different concentrations of each phosphate were used. Sensitivity of the bacterial strains to phosphates was observed in broth supplemented with salts. In vitro was showed a negative effect of various phosphates on growth of selected gram-positive bacteria. Orthophosphates and diphosphates (pyrophosphates did not have significant inhibitory effect on tested bacteria at neutral pH. With the exception of phosphate Trikrystal has not been found in vitro significant inhibitory effects on gram-negative bacteria.doi:10.5219/141

  17. Chloroform induces outstanding crystallization of poly(hydroxybutyrate) (PHB) vesicles within bacteria.

    Science.gov (United States)

    Rebois, Rolando; Onidas, Delphine; Marcott, Curtis; Noda, Isao; Dazzi, Alexandre

    2017-03-01

    Poly[(R)-3-hydroxyalkanoate]s or PHAs are aliphatic polyesters produced by numerous microorganisms. They are accumulated as energy and carbon reserve in the form of small intracellular vesicles. Poly[(R)-3-hydroxybutyrate] (PHB) is the most ubiquitous and simplest PHA. An atomic force microscope coupled with a tunable infrared laser (AFM-IR) was used to record highly spatially resolved infrared spectra of commercial purified PHB and native PHB within bacteria. For the first time, the crystallinity degree of native PHB within vesicle has been directly evaluated in situ without alteration due to the measure or extraction and purification steps of the polymer: native PHB is in crystalline state at 15% whereas crystallinity degree reaches 57% in commercial PHB. Chloroform addition on native PHB induces crystallization of the polymer within bacteria up to 60%. This possibility of probing and changing the physical state of polymer in situ could open alternative ways of production for PHB and others biopolymers. Graphical abstract An atomic force microscope coupled with a tunable infrared laser (AFM-IR) has been used to record local infrared spectra of biopolymer PHB within bacteria. Deconvolution of those spectra has allowed to determine in situ the crystallinity degree of native PHB.

  18. Peptidoglycan recognition proteins kill bacteria by inducing oxidative, thiol, and metal stress.

    Directory of Open Access Journals (Sweden)

    Des Raj Kashyap

    2014-07-01

    Full Text Available Mammalian Peptidoglycan Recognition Proteins (PGRPs are a family of evolutionary conserved bactericidal innate immunity proteins, but the mechanism through which they kill bacteria is unclear. We previously proposed that PGRPs are bactericidal due to induction of reactive oxygen species (ROS, a mechanism of killing that was also postulated, and later refuted, for several bactericidal antibiotics. Here, using whole genome expression arrays, qRT-PCR, and biochemical tests we show that in both Escherichia coli and Bacillus subtilis PGRPs induce a transcriptomic signature characteristic of oxidative stress, as well as correlated biochemical changes. However, induction of ROS was required, but not sufficient for PGRP killing. PGRPs also induced depletion of intracellular thiols and increased cytosolic concentrations of zinc and copper, as evidenced by transcriptome changes and supported by direct measurements. Depletion of thiols and elevated concentrations of metals were also required, but by themselves not sufficient, for bacterial killing. Chemical treatment studies demonstrated that efficient bacterial killing can be recapitulated only by the simultaneous addition of agents leading to production of ROS, depletion of thiols, and elevation of intracellular metal concentrations. These results identify a novel mechanism of bacterial killing by innate immunity proteins, which depends on synergistic effect of oxidative, thiol, and metal stress and differs from bacterial killing by antibiotics. These results offer potential targets for developing new antibacterial agents that would kill antibiotic-resistant bacteria.

  19. Biomineralization processes of calcite induced by bacteria isolated from marine sediments.

    Science.gov (United States)

    Wei, Shiping; Cui, Hongpeng; Jiang, Zhenglong; Liu, Hao; He, Hao; Fang, Nianqiao

    2015-06-01

    Biomineralization is a known natural phenomenon associated with a wide range of bacterial species. Bacterial-induced calcium carbonate precipitation by marine isolates was investigated in this study. Three genera of ureolytic bacteria, Sporosarcina sp., Bacillus sp. and Brevundimonas sp. were observed to precipitate calcium carbonate minerals. Of these species, Sporosarcina sp. dominated the cultured isolates. B. lentus CP28 generated higher urease activity and facilitated more efficient precipitation of calcium carbonate at 3.24 ± 0.25 × 10(-4) mg/cell. X-ray diffraction indicated that the dominant calcium carbonate phase was calcite. Scanning electron microscopy showed that morphologies of the minerals were dominated by cubic, rhombic and polygonal plate-like crystals. The dynamic process of microbial calcium carbonate precipitation revealed that B. lentus CP28 precipitated calcite crystals through the enzymatic hydrolysis of urea, and that when ammonium ion concentrations reached 746 mM and the pH reached 9.6, that favored calcite precipitation at a higher level of 96 mg/L. The results of this research provide evidence that a variety of marine bacteria can induce calcium carbonate precipitation, and may influence the marine carbonate cycle in natural environments.

  20. Antimicrobial Photodynamic Therapy to Kill Gram-negative Bacteria

    Science.gov (United States)

    Sperandio, Felipe F; Huang, Ying-Ying; Hamblin, Michael R

    2013-01-01

    Antimicrobial photodynamic therapy (PDT) or photodynamic inactivation (PDI) is a new promising strategy to eradicate pathogenic microorganisms such as Gram-positive and Gram-negative bacteria, yeasts and fungi. The search for new approaches that can kill bacteria but do not induce the appearance of undesired drug-resistant strains suggests that PDT may have advantages over traditional antibiotic therapy. PDT is a non-thermal photochemical reaction that involves the simultaneous presence of visible light, oxygen and a dye or photosensitizer (PS). Several PS have been studied for their ability to bind to bacteria and efficiently generate reactive oxygen species (ROS) upon photostimulation. ROS are formed through type I or II mechanisms and may inactivate several classes of microbial cells including Gram-negative bacteria such as Pseudomonas aeruginosa, which are typically characterized by an impermeable outer cell membrane that contains endotoxins and blocks antibiotics, dyes, and detergents, protecting the sensitive inner membrane and cell wall. This review covers significant peer-reviewed articles together with US and World patents that were filed within the past few years and that relate to the eradication of Gram-negative bacteria via PDI or PDT. It is organized mainly according to the nature of the PS involved and includes natural or synthetic food dyes; cationic dyes such as methylene blue and toluidine blue; tetrapyrrole derivatives such as phthalocyanines, chlorins, porphyrins, chlorophyll and bacteriochlorophyll derivatives; functionalized fullerenes; nanoparticles combined with different PS; other formulations designed to target PS to bacteria; photoactive materials and surfaces; conjugates between PS and polycationic polymers or antibodies; and permeabilizing agents such as EDTA, PMNP and CaCl2. The present review also covers the different laboratory animal models normally used to treat Gram-negative bacterial infections with antimicrobial PDT. PMID

  1. Infective Endocarditis: Identification of Catalase-Negative, Gram-Positive Cocci from Blood Cultures by Partial 16S rRNA Gene Analysis and by Vitek 2 Examination

    DEFF Research Database (Denmark)

    Abdul-Redha, Rawaa Jalil; Kemp, Michael; Bangsborg, Jette M

    2010-01-01

    Streptococci, enterococci and Streptococcus-like bacteria are frequent etiologic agents of infective endocarditis and correct species identification can be a laboratory challenge. Viridans streptococci (VS) not seldomly cause contamination of blood cultures. Vitek 2 and partial sequencing of the 16......S rRNA gene were applied in order to compare the results of both methods. STRAINS ORIGINATED FROM TWO GROUPS OF PATIENTS: 149 strains from patients with infective endocarditis and 181 strains assessed as blood culture contaminants. Of the 330 strains, based on partial 16S rRNA gene sequencing......-agreeing identifications with the two methods with respect to allocation to the same VS group. Non-agreeing species identification mostly occurred among strains in the contaminant group, while for endocarditis strains notably fewer disagreeing results were observed.Only 67 of 150 strains in the mitis group strains...

  2. Modeling of kinetics of the inducible protein complexes of the SOS system in bacteria E. coli which realize TLS process

    International Nuclear Information System (INIS)

    Belov, O.V.

    2008-01-01

    The mathematical model describing kinetics of the inducible genes of the protein complexes, formed during SOS response in bacteria Escherichia coli is developed. Within the bounds of developed approaches the auxiliary mathematical model describing changes in concentrations of the dimers, which are the components of final protein complexes, is developed. The solutions of both models are based on the experimental data concerning expression of the basic genes of the SOS system in bacteria Escherichia coli

  3. Recovery of metallo-tolerant and antibiotic resistant psychrophilic bacteria from Siachen glacier, Pakistan.

    Directory of Open Access Journals (Sweden)

    Muhammad Rafiq

    Full Text Available Cultureable bacterial diversity of previously unexplored Siachen glacier, Pakistan, was studied. Out of 50 isolates 33 (66% were Gram negative and 17 (34% Gram positive. About half of the isolates were pigment producers and were able to grow at 4-37°C. 16S rRNA gene sequences revealed Gram negative bacteria dominated by Proteobacteria (especially γ-proteobacteria and β-proteobacteria and Flavobacteria. The genus Pseudomonas (51.51%, 17 was dominant among γ- proteobacteria. β-proteobacteria constituted 4 (12.12% Alcaligenes and 4 (12.12% Janthinobacterium strains. Among Gram positive bacteria, phylum Actinobacteria, Rhodococcus (23.52%, 4 and Arthrobacter (23.52%, 4 were the dominating genra. Other bacteria belonged to Phylum Firmicutes with representative genus Carnobacterium (11.76%, 2 and 4 isolates represented 4 genera Bacillus, Lysinibacillus, Staphylococcus and Planomicrobium. Most of the Gram negative bacteria were moderate halophiles, while most of the Gram positives were extreme halophiles and were able to grow up to 6.12 M of NaCl. More than 2/3 of the isolates showed antimicrobial activity against multidrug resistant S. aureus, E. coli, Klebsiella pneumonia, Enterococcus faecium, Candida albicans, Aspergillus flavus and Aspergillus fumigatus and ATCC strains. Gram positive bacteria (94.11% were more resistant to heavy metals as compared to Gram negative (78.79% and showed maximum tolerance against iron and least tolerance against mercury.

  4. Macroalgal Morphogenesis Induced by Waterborne Compounds and Bacteria in Coastal Seawater.

    Directory of Open Access Journals (Sweden)

    Jan Grueneberg

    Full Text Available Axenic gametes of the marine green macroalga Ulva mutabilis Føyn (Ria Formosa, locus typicus exhibit abnormal development into slow-growing callus-like colonies with aberrant cell walls. Under laboratory conditions, it was previously demonstrated that all defects in growth and thallus development can be completely abolished when axenic gametes are inoculated with a combination of two specific bacterial strains originally identified as Roseobacter sp. strain MS2 and Cytophaga sp. strain MS6. These bacteria release diffusible morphogenetic compounds (= morphogens, which act similar to cytokinin and auxin. To investigate the ecological relevance of the waterborne bacterial morphogens, seawater samples were collected in the Ria Formosa lagoon (Algarve, Southern Portugal at 20 sampling sites and tidal pools to assess their morphogenetic effects on the axenic gametes of U. mutabilis. Specifically the survey revealed that sterile-filtered seawater samples can completely recover growth and morphogenesis of U. mutabilis under axenic conditions. Morphogenetic activities of free-living and epiphytic bacteria isolated from the locally very abundant Ulva species (i.e., U. rigida were screened using a multiwell-based testing system. The most represented genera isolated from U. rigida were Alteromonas, Pseudoalteromonas and Sulfitobacter followed by Psychrobacter and Polaribacter. Several naturally occurring bacterial species could emulate MS2 activity (= induction of cell divisions regardless of taxonomic affiliation, whereas the MS6 activity (= induction of cell differentiation and cell wall formation was species-specific and is probably a feature of difficult-to-culture bacteria. Interestingly, isolated bacteroidetes such as Algoriphagus sp. and Polaribacter sp. could individually trigger complete Ulva morphogenesis and thus provide a novel mode of action for bacterial-induced algal development. This study also highlights that the accumulation of algal

  5. Bee Venom (Apis Mellifera an Effective Potential Alternative to Gentamicin for Specific Bacteria Strains Bee Venom an Effective Potential for Bacteria

    Directory of Open Access Journals (Sweden)

    Hossein Zolfagharian

    2016-09-01

    Full Text Available Objectives: Mellitine, a major component of bee venom (BV, Apis mellifera, is more active against gram positive than gram negative bacteria. Moreover, BV has been reported to have multiple effects, including antibacterial, antivirus, and anti-inflammation effects, in various types of cells. In addition, wasp venom has bee

  6. Targeted mutations induced by a single acetylaminofluorene DNA adduct in mammalian cells and bacteria

    International Nuclear Information System (INIS)

    Moryia, M.; Takeshita, M.; Johnson, F.; Peden, K.; Will, S.; Grollman, A.P.

    1988-01-01

    Mutagenic specificity of 2-acetylaminofluorene (AAF) has been established in mammalian cells and several strains of bacteria by using a shuttle plasmid vector containing a single N-(deoxyguanosin-8-yl)acetylaminofluorene (C8-dG-AAF) adduct. The nucleotide sequence of the gene conferring tetracycline resistance was modified by conservative codon replacement so as to accommodate the sequence d(CCTTCGCTAC) flanked by two restriction sites, Bsm I and Xho I. The corresponding synthetic oligodeoxynucleotide underwent reaction with 2-(N-acetoxy-N-acetylamino)-fluorene (AAAF), forming a single dG-AAF adduct. This modified oligodeoxynucleotide was hybridized to its complementary strand and ligated between the Bsm I and Xho I sites of the vector. Plasmids containing the C8-dG-AAF adduct were used to transfect simian virus 40-transformed simian kidney (COS-1) cells and to transform several AB strains of Escherichia coli. Colonies containing mutant plasmides were detected by hybridization to 32 P-labeled oligodeoxynucleotides. Presence of the single DNA adduct increased the mutation frequency by 8-fold in both COS cells and E. coli. Over 80% of mutations detected in both systems were targeted and represented G x C → C x G or G x C → T x A transversions or single nucleotide deletions. The authors conclude that modification of a deoxyguanosine residue with AAF preferentially induces mutations targeted at this site when a plasmid containing a single C8-dG-AAF adduct is introduced into mammalian cells or bacteria

  7. Use of ethanol extracts of Terminalia chebula to prevent periodontal disease induced by dental plaque bacteria.

    Science.gov (United States)

    Lee, Jongsung; Nho, Youn Hwa; Yun, Seok Kyun; Hwang, Young Sun

    2017-02-16

    The fruit of the Terminalia chebula tree has been widely used for the treatment of various disorders. Its anti-diabetic, anti-mutagenic, anti-oxidant, anti-bacterial, anti-fungal, and anti-viral effects have been studied. Dental plaque bacteria (DPB) are intimately associated with gingivitis and periodontitis. In the quest for materials that will prove useful in the treatment and prevention of periodontal disease, we investigated the preventive effects of an ethanol extract of Terminalia chebula (EETC) on DPB-induced inflammation and bone resorption. The anti-bacterial effect of EETC was analyzed using the disc diffusion method. The anti-inflammatory effect of EETC was determined by molecular biological analysis of the DPB-mediated culture cells. Prevention of osteoclastic bone resorption by EETC was explored using osteoclast formation and pit formation assays. EETC suppressed the growth of oral bacteria and reduced the induction of inflammatory cytokines and proteases, abolishing the expression of PGE2 and COX-2 and inhibiting matrix damage. By stimulating the DPB-derived lipopolysaccharides, EETC inhibited both osteoclast formation in osteoclast precursors and RANKL expression in osteoblasts, thereby contributing to the prevention of bone resorption. EETC may be a beneficial supplement to help prevent DPB-mediated periodontal disease.

  8. Oil spill dispersants induce formation of marine snow by phytoplankton-associated bacteria.

    Science.gov (United States)

    van Eenennaam, Justine S; Wei, Yuzhu; Grolle, Katja C F; Foekema, Edwin M; Murk, AlberTinka J

    2016-03-15

    Unusually large amounts of marine snow, including Extracellular Polymeric Substances (EPS), were formed during the 2010 Deepwater Horizon oil spill. The marine snow settled with oil and clay minerals as an oily sludge layer on the deep sea floor. This study tested the hypothesis that the unprecedented amount of chemical dispersants applied during high phytoplankton densities in the Gulf of Mexico induced high EPS formation. Two marine phytoplankton species (Dunaliella tertiolecta and Phaeodactylum tricornutum) produced EPS within days when exposed to the dispersant Corexit 9500. Phytoplankton-associated bacteria were shown to be responsible for the formation. The EPS consisted of proteins and to lesser extent polysaccharides. This study reveals an unexpected consequence of the presence of phytoplankton. This emphasizes the need to test the action of dispersants under realistic field conditions, which may seriously alter the fate of oil in the environment via increased marine snow formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Apoptosis-like death in bacteria induced by HAMLET, a human milk lipid-protein complex.

    Directory of Open Access Journals (Sweden)

    Anders P Hakansson

    Full Text Available BACKGROUND: Apoptosis is the primary means for eliminating unwanted cells in multicellular organisms in order to preserve tissue homeostasis and function. It is characterized by distinct changes in the morphology of the dying cell that are orchestrated by a series of discrete biochemical events. Although there is evidence of primitive forms of programmed cell death also in prokaryotes, no information is available to suggest that prokaryotic death displays mechanistic similarities to the highly regulated programmed death of eukaryotic cells. In this study we compared the characteristics of tumor and bacterial cell death induced by HAMLET, a human milk complex of alpha-lactalbumin and oleic acid. METHODOLOGY/PRINCIPAL FINDINGS: We show that HAMLET-treated bacteria undergo cell death with mechanistic and morphologic similarities to apoptotic death of tumor cells. In Jurkat cells and Streptococcus pneumoniae death was accompanied by apoptosis-like morphology such as cell shrinkage, DNA condensation, and DNA degradation into high molecular weight fragments of similar sizes, detected by field inverse gel electrophoresis. HAMLET was internalized into tumor cells and associated with mitochondria, causing a rapid depolarization of the mitochondrial membrane and bound to and induced depolarization of the pneumococcal membrane with similar kinetic and magnitude as in mitochondria. Membrane depolarization in both systems required calcium transport, and both tumor cells and bacteria were found to require serine protease activity (but not caspase activity to execute cell death. CONCLUSIONS/SIGNIFICANCE: Our results suggest that many of the morphological changes and biochemical responses associated with apoptosis are present in prokaryotes. Identifying the mechanisms of bacterial cell death has the potential to reveal novel targets for future antimicrobial therapy and to further our understanding of core activation mechanisms of cell death in eukaryote cells.

  10. Apoptosis-like death in bacteria induced by HAMLET, a human milk lipid-protein complex.

    Science.gov (United States)

    Hakansson, Anders P; Roche-Hakansson, Hazeline; Mossberg, Ann-Kristin; Svanborg, Catharina

    2011-03-10

    Apoptosis is the primary means for eliminating unwanted cells in multicellular organisms in order to preserve tissue homeostasis and function. It is characterized by distinct changes in the morphology of the dying cell that are orchestrated by a series of discrete biochemical events. Although there is evidence of primitive forms of programmed cell death also in prokaryotes, no information is available to suggest that prokaryotic death displays mechanistic similarities to the highly regulated programmed death of eukaryotic cells. In this study we compared the characteristics of tumor and bacterial cell death induced by HAMLET, a human milk complex of alpha-lactalbumin and oleic acid. We show that HAMLET-treated bacteria undergo cell death with mechanistic and morphologic similarities to apoptotic death of tumor cells. In Jurkat cells and Streptococcus pneumoniae death was accompanied by apoptosis-like morphology such as cell shrinkage, DNA condensation, and DNA degradation into high molecular weight fragments of similar sizes, detected by field inverse gel electrophoresis. HAMLET was internalized into tumor cells and associated with mitochondria, causing a rapid depolarization of the mitochondrial membrane and bound to and induced depolarization of the pneumococcal membrane with similar kinetic and magnitude as in mitochondria. Membrane depolarization in both systems required calcium transport, and both tumor cells and bacteria were found to require serine protease activity (but not caspase activity) to execute cell death. Our results suggest that many of the morphological changes and biochemical responses associated with apoptosis are present in prokaryotes. Identifying the mechanisms of bacterial cell death has the potential to reveal novel targets for future antimicrobial therapy and to further our understanding of core activation mechanisms of cell death in eukaryote cells.

  11. In vitro activity of tigecycline and comparator agents against a global collection of Gram-negative and Gram-positive organisms: tigecycline Evaluation and Surveillance Trial 2004 to 2007.

    Science.gov (United States)

    Garrison, Mark W; Mutters, Reinier; Dowzicky, Michael J

    2009-11-01

    The Tigecycline Evaluation and Surveillance Trial began in 2004 to monitor the in vitro activity of tigecycline and comparator agents against a global collection of Gram-negative and Gram-positive pathogens. Against Gram negatives (n = 63 699), tigecycline MIC(90)'s ranged from 0.25 to 2 mg/L for Escherichia coli, Haemophilus influenzae, Acinetobacter baumannii, Klebsiella oxytoca, Enterobacter cloacae, Klebsiella pneumoniae, and Serratia marcescens (but was > or =32 for Pseudomonas aeruginosa). Against Gram-positive organisms (n = 32 218), tigecycline MIC(90)'s were between 0.06 and 0.25 mg/L for Streptococcus pneumoniae, Enterococcus faecium, Streptococcus agalactiae, Staphylococcus aureus, and Enterococcus faecalis. The in vitro activity of tigecycline was maintained against resistant phenotypes, including multidrug-resistant A. baumannii (9.2% of isolates), extended-spectrum beta-lactamase-producing E. coli (7.0%) and K. pneumoniae (14.0%), beta-lactamase-producing H. influenzae (22.2%), methicillin-resistant S. aureus (44.5%), vancomycin-resistant E. faecium (45.9%) and E. faecalis (2.8%), and penicillin-resistant S. pneumoniae (13.8%). Tigecycline represents a welcome addition to the armamentarium against difficult to treat organisms.

  12. Identification and discrimination of Pseudomonas aeruginosa bacteria grown in blood and bile by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Rehse, Steven J.; Diedrich, Jonathan; Palchaudhuri, Sunil

    2007-01-01

    Pseudomonas aeruginosa bacteria colonies have been analyzed by laser-induced breakdown spectroscopy using nanosecond laser pulses. LIBS spectra were obtained after transferring the bacteria from a nutrient-rich culture medium to a nutrient-free agar plate for laser ablation. To study the dependence of the LIBS spectrum on growth and environmental conditions, colonies were cultured on three different nutrient media: a trypticase soy agar (TSA) plate, a blood agar plate, and a medium chosen deliberately to induce bacteria membrane changes, a MacConkey agar plate containing bile salts. Nineteen atomic and ionic emission lines in the LIBS spectrum, which was dominated by inorganic elements such as calcium, magnesium and sodium, were used to identify and classify the bacteria. A discriminant function analysis was used to discriminate between the P. aeruginosa bacteria and two strains of E. coli: a non-pathogenic environmental strain and the pathogenic strain enterohemorrhagic E. coli 0157:H7 (EHEC). Nearly identical spectra were obtained from P. aeruginosa grown on the TSA plate and the blood agar plate, while the bacteria grown on the MacConkey plate exhibited easily distinguishable differences from the other two. All P. aeruginosa samples, independent of initial growth conditions, were readily discriminated from the two E. coli strains

  13. Removal of bacteria Legionella pneumophila, Escherichia coli, and Bacillus subtilis by (super)cavitation.

    Science.gov (United States)

    Šarc, Andrej; Kosel, Janez; Stopar, David; Oder, Martina; Dular, Matevž

    2018-04-01

    In sufficient concentrations, the pathogenic bacteria L. pneumophila can cause a respiratory illness that is known as the "Legionnaires" disease. Moreover, toxic Shiga strains of bacteria E. coli can cause life-threatening hemolytic-uremic syndrome. Because of the recent restrictions imposed on the usage of chlorine, outbreaks of these two bacterial species have become more common. In this study we have developed a novel rotation generator and its effectiveness against bacteria Legionella pneumophila and Escherichia coli was tested for various types of hydrodynamic cavitation (attached steady cavitation, developed unsteady cavitation and supercavitation). The results show that the supercavitation was the only effective form of cavitation. It enabled more than 3 logs reductions for both bacterial species and was also effective against a more persistent Gram positive bacteria, B. subtilis. The deactivation mechanism is at present unknown. It is proposed that when bacterial cells enter a supercavitation cavity, an immediate pressure drop occurs and this results in bursting of the cellular membrane. The new rotation generator that induced supercavitation proved to be economically and microbiologically far more effective than the classical Venturi section (super)cavitation. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Slippery liquid-infused porous surfaces fabricated on aluminum as a barrier to corrosion induced by sulfate reducing bacteria

    International Nuclear Information System (INIS)

    Wang, Peng; Lu, Zhou; Zhang, Dun

    2015-01-01

    Highlights: • Slippery liquid-infused porous surfaces (SLIPS) were fabricated over aluminum. • SLIPS depress the adherence of sulfate reducing bacteria in static seawater. • SLIPS inhibit the microbiological corrosion of aluminum in static seawater. • The possible microbiological corrosion protection mechanism of SLIPS is proposed. - Abstract: Microbiological corrosion induced by sulfate reducing bacteria (SRB) is one of the main threatens to the safety of marine structure. To reduce microbiological corrosion, slippery liquid infused porous surfaces (SLIPS) were designed and fabricated on aluminum substrate by constructing rough aluminum oxide layer, followed by fluorination of the rough layer and infiltration with lubricant. The as-fabricated SLIPS were characterized with wettability measurement, SEM and XPS. Their resistances to microbiological corrosion induced by SRB were evaluated with fluorescence microscopy and electrochemical measurement. It was demonstrated that they present high resistance to bacteria adherence and the resultant microbiological corrosion in static seawater

  15. Functional Diversity of Tandem Substrate-Binding Domains in ABC Transporters from Pathogenic Bacteria

    NARCIS (Netherlands)

    Fulyani, Faizah; Schuurman-Wolters, Gea K.; Vujicic - Zagar, Andreja; Guskov, Albert; Slotboom, Dirk-Jan; Poolman, Bert

    2013-01-01

    The ATP-binding cassette (ABC) transporter GInPQ is an essential uptake system for amino acids in gram-positive pathogens and related nonpathogenic bacteria. The transporter has tandem substrate-binding domains (SBDs) fused to each transmembrane domain, giving rise to four SBDs per functional

  16. Antibacterial activities of ethanol extracts of Philippine medicinal plants against multidrug-resistant bacteria

    Directory of Open Access Journals (Sweden)

    Demetrio L. Valle Jr.

    2015-07-01

    Conclusions: P. betle had the greatest potential value against both Gram-negative and Gram-positive multidrug-resistant bacteria. Favorable antagonistic activities were also exhibited by the ethanol extracts of Psidium guajava, Phyllanthus niruri and Ehretia microphylla.

  17. Photocatalytic disinfection of spoilage bacteria Pseudomonas fluorescens and Macrococcus caseolyticus by nano-TiO2

    Science.gov (United States)

    Photocatalytic disinfection of spoilage bacteria gram-negative (G-) P. fluorescens and gram-positive (G+) M. caseolyticus by nano-TiO2 under different experimental conditions and the disinfection mechanism were investigated. The experimental conditions included the initial bacterial populations, nan...

  18. Bacillus methanolicus sp. nov., a New Species of Thermotolerant, Methanol-Utilizing, Endospore-Forming Bacteria

    NARCIS (Netherlands)

    Arfman, Nico; Dijkhuizen, Lubbert; Kirchhof, Gudrun; Ludwig, Wolfgang; Schleifer, Karl-Heinz; Bulygina, Eugenia S.; Chumakov, Konstantin M.; Govorukhina, Natalya I.; Trotsenko, Yuri A.; White, Duncan; Sharp, Richard J.

    1992-01-01

    The generic position of 14 strains of gram-positive bacteria able to use methanol as a growth substrate was determined. All are obligately aerobic, thermotolerant organisms that are able to grow at temperatures of 35 to 60°C. Nine of the strains produce oval spores at a subterminal-to-central

  19. Structure, diversity and evolution of protein toxins from spore-forming entomopathogenic bacteria

    NARCIS (Netherlands)

    Maagd, de R.A.; Bravo, A.; Berry, C.; Crickmore, N.; Schnepf, H.E.

    2003-01-01

    Gram-positive spore-forming entomopathogenic bacteria can utilize a large variety of protein toxins to help them invade, infect, and finally kill their hosts, through their action on the insect midgut. These toxins belong to a number of homology groups containing a diversity of protein structures

  20. When it comes to antibiotics, bacteria show some NO-how.

    Science.gov (United States)

    Patel, Bhumit A; Crane, Brian R

    2010-10-01

    Homologs to mammalian nitric oxide synthases are found in many mostly Gram-positive bacteria. In some genera such as bacilli, and staphylococci, these enzymes produce protects against oxidative damage, this effect has now been shown to provide an advantage against antibiotics that kill by increasing cellular levels of reactive oxygen species.

  1. Effects of inulin chain length on fermentation by equine fecal bacteria and Streptococcus bovis

    Science.gov (United States)

    Fructans from pasture can be fermented by Gram-positive bacteria (e.g., Streptococcus bovis) in the equine hindgut, increasing production of lactic acid and decreasing pH. The degree of polymerization (DP) of fructans has been suggested to influence fermentation rates. The objective of the current ...

  2. Lipopolysaccharide induces amyloid formation of antimicrobial peptide HAL-2.

    Science.gov (United States)

    Wang, Jiarong; Li, Yan; Wang, Xiaoming; Chen, Wei; Sun, Hongbin; Wang, Junfeng

    2014-11-01

    Lipopolysaccharide (LPS), the important component of the outer membrane of Gram-negative bacteria, contributes to the integrity of the outer membrane and protects the cell against bactericidal agents, including antimicrobial peptides. However, the mechanisms of interaction between antimicrobial peptides and LPS are not clearly understood. Halictines-2 (HAL-2), one of the novel antimicrobial peptides, was isolated from the venom of the eusocial bee Halictus sexcinctus. HAL-2 has exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria and even against cancer cells. Here, we studied the interactions between HAL-2 and LPS to elucidate the antibacterial mechanism of HAL-2 in vitro. Our results show that HAL-2 adopts a significant degree of β-strand structure in the presence of LPS. LPS is capable of inducing HAL-2 amyloid formation, which may play a vital role in its antimicrobial activity. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Antimicrobial resistance in bacteria from breeding dogs housed in kennels with differing neonatal mortality and use of antibiotics.

    Science.gov (United States)

    Milani, C; Corrò, M; Drigo, M; Rota, A

    2012-10-01

    This work examines the antimicrobial resistance of potentially pathogenic bacteria (Staphylococcus pseudintermedius, Streptococcus canis, Escherichia coli) found in the vaginal tract in prepartum mammary secretions and postpartum milk of bitches housed in breeding kennels (N = 20; 92 bitches). The kennels were divided into three categories: no routine antimicrobial administration around parturition (category 1); routine administration of one antibiotic around parturition (category 2); routine administration of multiple antimicrobials around parturition (category 3). Bacteriological cultures and antibiotic susceptibility tests were performed on vaginal specimens, prepartum mammary secretions, and postpartum milk. Stillbirths and neonatal deaths were recorded for each whelping and analyzed as "within-litter stillbirths" and "within-litter neonatal deaths" according to kennel category, by Pearson χ(2) test and the Kruskal-Wallis nonparametric test, respectively. The frequency of isolation and antimicrobial resistance of bacteria were analyzed according to kennel category by Pearson χ(2) test. Kennel category was not significantly associated with differing numbers of stillbirths or neonatal death events, nor was the frequency of isolation of potentially pathogenic bacteria in the three kennel categories significantly different. Kennel category 3 had a significantly higher frequency of isolation of multiresistant gram-positive bacterial strains. Our results show that intense administration of antibiotics to breeding bitches does not effectively reduce neonatal mortality; on the contrary, it induces multiresistance in potentially pathogenic bacteria. Breeders and veterinarians should be aware of the risk of selecting pathogenic bacteria by uncontrolled treatment in prepartum bitches. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Screening identification of aerobic denitrification bacteria with high soil desalinization capacity

    Science.gov (United States)

    Jin, H.; Chen, H.; Jin, H.; Qian, Y.; Zhang, K.

    2017-08-01

    In order to study the mechanism of bacteria used in the saline soil remediation process, the aerobic denitrification bacteria were isolated from an agricultural greenhouse soil in a farm in East China’s Zhejiang Province. The identification, nitrogen reducing characteristics and the denitrification effect of bacteria from different soils at various locations were investigated. The results showed that the NO3- removal rate was 91% with bacteria from the greenhouse soil under aerobic conditions in 52 h, and the bacteria were identified as Gram-positive Castellaniella denitrification bacteria.

  5. Investigation of isotopic and biomolecular approaches as new bio-indicators for long term natural attenuation of monoaromatic compounds in deep terrestrial aquifers by gram-positive sporulated sulfate-reducing bacteria of the genus Desulfotomaculum.

    Directory of Open Access Journals (Sweden)

    Thomas eAüllo

    2016-02-01

    Full Text Available Deep subsurface aquifers despite difficult access, represent important water resources and, at the same time, are key locations for subsurface engineering activities for the oil and gas industries, geothermal energy and CO2 or energy storage. Formation water originating from a 760 meter-deep geological gas storage aquifer was sampled and microcosms were set up to test the biodegradation potential of BTEX by indigenous microorganisms. After a long incubation period, with several subcultures, a sulfate-reducing consortium composed of only two Desulfotomaculum populations was observed able to degrade benzene, toluene and ethylbenzene, extending the number of hydrocarbonoclastic–related species among the Desulfotomaculum genus. Furthermore, we were able to couple specific carbon and hydrogen isotopic fractionation during benzene removal and the results obtained by dual compound specific isotope analysis (εC = -2.4 ‰ ± 0.3 ‰; εH = -57 ‰ ± 0.98 ‰; AKIEC: 1.0146 ± 0.0009 and AKIEH: 1.5184 ± 0.0283 were close to those obtained previously in sulfate-reducing conditions: this finding could confirm the existence of a common enzymatic reaction involving sulfate-reducers to activate benzene anaerobically. Although we cannot assign the role of each population of Desulfotomaculum in the mono-aromatic hydrocarbon degradation, this study suggests an important role of the genus Desulfotomaculum as potential biodegrader among indigenous populations in subsurface habitats. This community represents the simplest model of benzene-degrading anaerobes originating from the deepest subterranean settings ever described. As Desulfotomaculum species are often encountered in subsurface environments, this study provides some interesting results for assessing the natural response of these specific hydrologic systems in response to BTEX contamination during remediation projects.

  6. Electron Microscopic Analysis and Structural Characterization of Novel NADP(H)-Containing Methanol : N,N'-Dimethyl-4-Nitrosoaniline Oxidoreductases from the Gram-Positive Methylotrophic Bacteria Amycolatopsis methanolica and Mycobacterium gastri MB19

    NARCIS (Netherlands)

    Bystrykh, Leonid V.; Vonck, Janet; Bruggen, Ernst F.J. van; Beeumen, Jozef van; Samyn, Bart; Govorukhina, Natalya I.; Arfman, Nico; Duine, Johannis A.; Dijkhuizen, Lubbert

    The quaternary protein structure of two methanol:N,N'-dimethyl-4-nitrosoaniline (NDMA) oxidoreductases purified from Amycolatopsis methanolica and Mycobacterium gastri MB19 was analyzed by electron microscopy and image processing. The enzymes are decameric proteins (displaying fivefold symmetry)

  7. Evaluation of staphylococcus aureus class C non-specific acid phosphatase (SapS) as a reporter for gene expression and protein secretion in gram-negative and gram-positive bacteria

    CSIR Research Space (South Africa)

    Du Plessis, EM

    2007-11-01

    Full Text Available deviation (SD). 10 SDS-PAGE was performed with 12% polyacrylamide gels by the method of Laemmli 11 (1970) after the samples had been heated at 37°C for 30 min. Molecular weight markers 12 (Bio-Rad) were included in each gel. Following electrophoresis... renaturation treatment, gels were equilibrated for 16 1 h at 37°C in 0.1 M sodium acetate buffer (pH 5), and incubated at 37°C for 15 min to 1 17 h in 0.1 M sodium acetate (pH 5) containing 0.1% (w/v) α-naphtyl phosphate and 0.2% 18 (w/v) Fast Garnet GBG...

  8. Effect of antigens from gram-positive and gram-negative bacteria, and of ŕ-gliadin on the intestinal epithelial cell lines HT-29, SW-480 and Caco-2

    Czech Academy of Sciences Publication Activity Database

    Funda, David P.; Farré, Maria Antionette; Horáková, Dana; Kolínská, Jiřina; Ceska, M.; Barot, R.; Tučková, Ludmila; Tlaskalová, Helena

    1997-01-01

    Roč. 75, č. 1 (1997), s. 52 ISSN 0818-9641. [International Congress of Mucosal Immunology /9./. 27.01.1997-31.01.1997, Sydney] R&D Projects: GA AV ČR IAA7020716; GA ČR GA310/96/1366; GA MZd IZ3761

  9. Activities of Tedizolid and Linezolid Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe, and Latin American Countries in 2014.

    Science.gov (United States)

    Pfaller, Michael A; Flamm, Robert K; Jones, Ronald N; Farrell, David J; Mendes, Rodrigo E

    2016-09-01

    Tedizolid and linezolid in vitro activities against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European, and Latin American medical centers during 2014 were assessed. The isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones tedizolid and linezolid, MIC endpoint values were read by two methods: (i) reading the MIC at the first well where the trailing began without regard for pinpoint trailing, according to CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., 80% inhibition of growth; these reads were designated tedizolid 80 and linezolid 80), and (ii) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, and Enterococcus faecalis isolates were inhibited at tedizolid 80 and 100 MIC values of 0.25 and 0.5, 0.25 and 0.25, 0.25 and 0.5, 0.12 and 0.25, and 0.5 and 1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling dilution lower than those read at 100% inhibition. Tedizolid was 4- to 8-fold more potent than linezolid against all the isolates tested regardless of the MIC endpoint criterion used. Despite the differences in potency, >99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI and EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency than linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific region, Eastern Europe, and Latin America. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  10. Five-Year Summary of In Vitro Activity and Resistance Mechanisms of Linezolid against Clinically Important Gram-Positive Cocci in the United States from the LEADER Surveillance Program (2011 to 2015).

    Science.gov (United States)

    Pfaller, Michael A; Mendes, Rodrigo E; Streit, Jennifer M; Hogan, Patricia A; Flamm, Robert K

    2017-07-01

    This report describes linezolid susceptibility testing results for 6,741 Gram-positive pathogens from 60 U.S. sites collected during 2015 for the LEADER Program. In addition, the report summarizes linezolid in vitro activity, resistance mechanisms, and molecular typing obtained for 2011 to 2015. During 2015, linezolid showed potent activity in testing against Staphylococcus aureus , inhibiting >99.9% of 3,031 isolates at ≤2 µg/ml. Similarly, linezolid showed coverage against 99.2% of coagulase-negative staphylococci, 99.7% of enterococci, and 100.0% of Streptococcus pneumoniae , virdans group, and beta-hemolytic streptococcus isolates tested. The overall linezolid resistance rate remained a modest linezolid resistance mechanisms. Increased annual trends for the presence of cfr among Staphylococcus aureus isolates were not observed, but 64.3% (9/14) of the isolates with decreased susceptibility (MIC, ≥4 µg/ml) to linezolid carried this transferrable gene (2011 to 2015). The cfr gene was detected in 21.9% (7/32) of linezolid-resistant staphylococci other than S. aureus from 2011 to 2015. The optrA gene was noted in half (2/4) of the population of linezolid-nonsusceptible Enterococcus faecalis isolates from 2011 to 2015, while linezolid-nonsusceptible Enterococcus faecium isolates showed alterations predominantly (16/16) in the 23S rRNA gene (G2576T). This report confirms a long record of linezolid activity against Gram-positive isolates in the United States since regulatory approval in 2000 and reports the oxazolidinones evolving resistance mechanisms. Copyright © 2017 American Society for Microbiology.

  11. Changes in antagonistic activity of lactic acid bacteria induced by their response to technological factors

    Directory of Open Access Journals (Sweden)

    Dovile Jonkuviene

    2015-12-01

    Full Text Available This study examined the changes in antagonistic activity of selected lactic acid bacteria (LAB in response to technological factors used in food production. The antimicrobial activity of 12 selected LAB strains was assessed against the bacterial and fungal strains using the agar well diffusion method. Sodium chloride (NaCl 6.5–8.0%, glucose 20-30% and pH 4.0, pH 8.0 and higher were the most crucial factors in reducing the spectra of the microorganisms antagonized. Heating at 80 °C or 100 °C had a greater negative impact than 63 °C on the antifungal activity of LAB. Freezing at –72 °C eliminated the antifungal activity, or it changed from fungicidal to fungistatic. Although each LAB demonstrated the ability to retain antimicrobial activity induced by various technological factors, Lactococcus lactis 768/5 was superior in retaining high antimicrobial activity against tested indicator strains.

  12. Effect of riboflavin-producing bacteria against chemically induced colitis in mice.

    Science.gov (United States)

    Levit, R; Savoy de Giori, G; de Moreno de LeBlanc, A; LeBlanc, J G

    2018-01-01

    To assess the anti-inflammatory effect associated with individual probiotic suspensions of riboflavin-producing lactic acid bacteria (LAB) in a colitis murine model. Mice intrarectally inoculated with trinitrobenzene sulfonic acid (TNBS) were orally administered with individual suspensions of riboflavin-producing strains: Lactobacillus (Lact.) plantarum CRL2130, Lact. paracasei CRL76, Lact. bulgaricus CRL871 and Streptococcus thermophilus CRL803; and a nonriboflavin-producing strain or commercial riboflavin. The extent of colonic damage and inflammation and microbial translocation to liver were evaluated. iNOs enzyme was analysed in the intestinal tissues and cytokine concentrations in the intestinal fluids. Animals given either one of the four riboflavin-producing strains showed lower macroscopic and histologic damage scores, lower microbial translocation to liver, significant decreases of iNOs+ cells in their large intestines and decreased proinflammatory cytokines, compared with mice without treatment. The administration of pure riboflavin showed similar benefits. Lact. paracasei CRL76 accompanied its anti-inflammatory effect with increased IL-10 levels demonstrating other beneficial properties in addition to the vitamin production. Administration of riboflavin-producing strains prevented the intestinal damage induced by TNBS in mice. Riboflavin-producing phenotype in LAB represents a potent tool to select them for preventing/treating IBD. © 2017 The Society for Applied Microbiology.

  13. Antibacterial and anti-inflammatory effects of Jeju medicinal plants against acne-inducing bacteria.

    Science.gov (United States)

    Kim, Sang-Suk; Kim, Ji-Young; Lee, Nam Ho; Hyun, Chang-Gu

    2008-04-01

    Propionibacterium acnes and Staphylococcus epidermidis are pus-forming bacteria that trigger inflammation in acne. The present study was conducted to evaluate the antimicrobial activities of Jeju medicinal plants against these etiologic agents of acne vulgaris. Ethanol extracts of Jeju plants were tested for antimicrobial activities by disc diffusion and broth dilution methods. The results from the disc diffusion assays revealed that four medicinal plants, Mollugo pentaphylla, Angelica anomala, Matteuccia orientalis, and Orixa japonica inhibited the growth of both pathogens. Among these, A. anomala had strong inhibitory effects. Its MIC values were 15.6 microg/ml and 125 microg/ml against P. acnes and S. epidermidis, respectively. The cytotoxic effects of the four extracts were determined by colorimetric MTT assays using two animal cell lines: human dermal fibroblasts and HaCaT cells. Although the M. orientalis root extract had moderate cytotoxicity in HaCaT cells at 200 microg/ml, most extracts exhibited low cytotoxicity at 200 microg/ml in both cell lines. In addition, the extracts reduced the P. acnes-induced secretion of interleukin-8 and tumor necrosis factor-alpha (TNF-alpha) in THP-1 cells, an indication of their anti-inflammatory effects. Based on these results, we suggest that M. pentaphylla, A. anomala, M. orientalis, and O. japonica are attractive acne-mitigating candidates for topical application.

  14. Continous application of bioorganic fertilizer induced resilient culturable bacteria community associated with banana Fusarium wilt suppression

    Science.gov (United States)

    Fu, Lin; Ruan, Yunze; Tao, Chengyuan; Li, Rong; Shen, Qirong

    2016-06-01

    Fusarium wilt of banana always drives farmers to find new land for banana cultivation due to the comeback of the disease after a few cropping years. A novel idea for solving this problem is the continuous application of bioorganic fertilizer (BIO), which should be practiced from the beginning of banana planting. In this study, BIO was applied in newly reclaimed fields to pre-control banana Fusarium wilt and the culturable rhizobacteria community were evaluated using Biolog Ecoplates and culture-dependent denaturing gradient gel electrophoresis (CD-DGGE). The results showed that BIO application significantly reduced disease incidences and increased crop yields, respectivly. And the stabilized general bacterial metabolic potential, especially for the utilization of carbohydrates, carboxylic acids and phenolic compounds, was induced by BIO application. DGGE profiles demonstrated that resilient community structure of culturable rhizobacteria with higher richness and diversity were observed in BIO treated soils. Morever, enriched culturable bacteria affiliated with Firmicutes, Gammaproteobacteria and Actinobacteria were also detected. In total, continuous application of BIO effectively suppressed Fusarium wilt disease by stabilizing culturable bacterial metabolic potential and community structure. This study revealed a new method to control Fusarium wilt of banana for long term banana cultivation.

  15. In vitro activity of mecillinam against anaerobic bacteria.

    OpenAIRE

    Steinkraus, G E; McCarthy, L R

    1980-01-01

    A microtiter broth dilution method was employed to determine the in vitro activity of mecillinam against 201 recent clinical isolates of anaerobic bacteria. Both the anerobic gram-positive and anaerobic gram-negative bacilli displayed a wide range of minimal inhibitory concentrations of mecillinam; most strains were resistant to the antibiotic. The anaerobic cocci exhibited a narrower range of minimal inhibitory concentrations than were observed with other anaerobes, but also exhibited mecill...

  16. [Application of anaerobic bacteria detection in oral and maxillofacial infection].

    Science.gov (United States)

    Bao, Zhen-ying; Lin, Qin; Meng, Yan-hong; He, Chun; Su, Jia-zeng; Peng, Xin

    2016-02-18

    To investigate the distribution and drug resistance of anaerobic bacteria in the patients with oral and maxillofacial infection. Aerobic and anaerobic bacteria cultures from 61 specimens of pus from the patients with oral and maxillofacial infection in the Department of Oral and Maxillofacial Surgery, Peking University School of Stomatology were identified. The culture type was evaluated by API 20A kit and drug resistance test was performed by Etest method. The clinical data and antibacterial agents for the treatment of the 61 cases were collected, and the final outcomes were recorded. The bacteria cultures were isolated from all the specimens, with aerobic bacteria only in 6 cases (9.8%), anaerobic bacteria only in 7 cases (11.5%), and both aerobic and anaerobic bacteria in 48 cases (78.7%). There were 55 infected cases (90.2%) with anaerobic bacteria, and 81 anaerobic bacteria stains were isolated. The highest bacteria isolation rate of Gram positive anaerobic bacteria could be found in Peptostreptococcus, Bifidobacterium and Pemphigus propionibacterium. No cefoxitin, amoxicillin/carat acid resistant strain was detected in the above three Gram positive anaerobic bacteria. The highest bacteria isolation rate of Gram negative anaerobic bacteria could be detected in Porphyromonas and Prevotella. No metronidazole, cefoxitin, amoxicillin/carat acid resistant strain was found in the two Gram negative anaerobic bacteria. In the study, 48 patients with oral and maxillofacial infection were treated according to the results of drug resistance testing, and the clinical cure rate was 81.3%. Mixed aerobic and anaerobic bacteria cultures are very common in most oral and maxillofacial infection patients. Anaerobic bacteria culture and drug resistance testing play an important role in clinical treatment.

  17. Antibacterial Activity of Some Lactic Acid Bacteria Isolated from an Algerian Dairy Product

    Directory of Open Access Journals (Sweden)

    Abdelkader Mezaini

    2009-01-01

    Full Text Available In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria. Streptococcus thermophilus T2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacteriocin production profiles showed that the maximal bacteriocin production, by S. thermophilus T2 cells, was measured by the end of the late-log phase (90 AU ml−1 with a bacteriocine production rate of 9.3 (AU ml−1 h−1. In addition, our findings showed that the bacteriocin, produced by S. thermophilus T2, was stable over a wide pH range (4–8; this indicates that such bacteriocin may be useful in acidic as well as nonacidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food.

  18. Antibacterial Activity of Some Lactic Acid Bacteria Isolated from an Algerian Dairy Product

    International Nuclear Information System (INIS)

    Mezaini, A.; Bouras, A.D.; Mezaini, A.; Chihib, N.; Nedjar-Arroume, N.; Hornez, J.P.

    2010-01-01

    In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria. Streptococcus thermophilus T2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacitracin production profiles showed that the maximal bacitracin production, by S. thermophilus T2 cells, was measured by the end of the late-log phase (90 AU ml -1 ) with a bacterio cine production rate of 9.3 (AU ml -1 ) h -1 . In addition, our findings showed that the bacitracin, produced by S. thermophilus T2, was stable over a wide ph range (4-8); this indicates that such bacitracin may be useful in acidic as well as non acidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food.

  19. Rapid, highly sensitive detection of Gram-negative bacteria with lipopolysaccharide based disposable aptasensor.

    Science.gov (United States)

    Zhang, Jian; Oueslati, Rania; Cheng, Cheng; Zhao, Ling; Chen, Jiangang; Almeida, Raul; Wu, Jayne

    2018-07-30

    Gram-negative bacteria are one of the most common microorganisms in the environment. Their differential detection and recognition from Gram-positive bacteria has been attracting much attention over the years. Using Escherichia coli (E. coli) as a model, we demonstrated on-site detection of Gram-negative bacteria by an AC electrokinetics-based capacitive sensing method using commercial microelectrodes functionalized with an aptamer specific to lipopolysaccharides. Dielectrophoresis effect was utilized to enrich viable bacteria to the microelectrodes rapidly, achieving a detection limit of 10 2 cells/mL within a 30 s' response time. The sensor showed a negligible response to Staphylococcus aureus (S. aureus), a Gram-positive species. The developed sensor showed significant advantages in sensitivity, selectivity, cost, operation simplicity, and response time. Therefore, this sensing method has shown great application potential for environmental monitoring, food safety, and real-time diagnosis. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Lactobacillus acidophilus induces a slow but more sustained chemokine and cytokine response in naïve foetal enterocytes compared to commensal Escherichia coli

    Directory of Open Access Journals (Sweden)

    Nellemann Christine

    2010-01-01

    Full Text Available Abstract Background The first exposure to microorganisms at mucosal surfaces is critical for immune maturation and gut health. Facultative anaerobic bacteria are the first to colonise the infant gut, and the impact of these bacteria on intestinal epithelial cells (IEC may be determinant for how the immune system subsequently tolerates gut bacteria. Results To mirror the influence of the very first bacterial stimuli on infant IEC, we isolated IEC from mouse foetuses at gestational day 19 and from germfree neonates. IEC were stimulated with gut-derived bacteria, Gram-negative Escherichia coli Nissle and Gram-positive Lactobacillus acidophilus NCFM, and expression of genes important for immune regulation was measured together with cytokine production. E. coli Nissle and L. acidophilus NCFM strongly induced chemokines and cytokines, but with different kinetics, and only E. coli Nissle induced down-regulation of Toll-like receptor 4 and up-regulation of Toll-like receptor 2. The sensitivity to stimulation was similar before and after birth in germ-free IEC, although Toll-like receptor 2 expression was higher before birth than immediately after. Conclusions In conclusion, IEC isolated before gut colonisation occurs at birth, are highly responsive to stimulation with gut commensals, with L. acidophilus NCFM inducing a slower, but more sustained response than E. coli Nissle. E. coli may induce intestinal tolerance through very rapid up-regulation of chemokine and cytokine genes and down-regulation of Toll-like receptor 4, while regulating also responsiveness to Gram-positive bacteria.

  1. Overcoming Antimicrobial Resistance in Bacteria Using Bioactive Magnetic Nanoparticles and Pulsed Electromagnetic Fields

    Directory of Open Access Journals (Sweden)

    Vitalij Novickij

    2018-01-01

    Full Text Available Nisin is a known bacteriocin, which exhibits a wide spectrum of antimicrobial activity, while commonly being inefficient against Gram-negative bacteria. In this work, we present a proof of concept of novel antimicrobial methodology using targeted magnetic nisin-loaded nano-carriers [iron oxide nanoparticles (NPs (11–13 nm capped with citric, ascorbic, and gallic acids], which are activated by high pulsed electric and electromagnetic fields allowing to overcome the nisin-resistance of bacteria. As a cell model the Gram-positive bacteria Bacillus subtilis and Gram-negative Escherichia coli were used. We have applied 10 and 30 kV cm-1 electric field pulses (100 μs × 8 separately and in combination with two pulsed magnetic field protocols: (1 high dB/dt 3.3 T × 50 and (2 10 mT, 100 kHz, 2 min protocol to induce additional permeabilization and local magnetic hyperthermia. We have shown that the high dB/dt pulsed magnetic fields increase the antimicrobial efficiency of nisin NPs similar to electroporation or magnetic hyperthermia methods and a synergistic treatment is also possible. The results of our work are promising for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections.

  2. Cold atmospheric-pressure plasma and bacteria: understanding the mode of action using vibrational microspectroscopy

    International Nuclear Information System (INIS)

    Kartaschew, Konstantin; Mischo, Meike; Bründermann, Erik; Havenith, Martina; Baldus, Sabrina; Awakowicz, Peter

    2016-01-01

    Cold atmospheric-pressure plasma show promising antimicrobial effects, however the detailed biochemical mechanism of the bacterial inactivation is still unknown. We investigated, for the first time, plasma-treated Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacteria with Raman and infrared microspectroscopy. A dielectric barrier discharge was used as a plasma source. We were able to detect several plasma-induced chemical modifications, which suggest a pronounced oxidative effect on the cell envelope, cellular proteins and nucleotides as well as a generation of organic nitrates in the treated bacteria. Vibrational microspectroscopy is used as a comprehensive and a powerful tool for the analysis of plasma interactions with whole organisms such as bacteria. Analysis of reaction kinetics of chemical modifications allow a time-dependent insight into the plasma-mediated impact. Investigating possible synergistic effects between the plasma-produced components, our observations strongly indicate that the detected plasma-mediated chemical alterations can be mainly explained by the particle effect of the generated reactive species. By changing the polarity of the applied voltage pulse, and hence the propagation mechanisms of streamers, no significant effect on the spectral results could be detected. This method allows the analysis of the individual impact of each plasma constituent for particular chemical modifications. Our approach shows great potential to contribute to a better understanding of plasma-cell interactions. (paper)

  3. Bacteria modulate the CD8+ T cell epitope repertoire of host cytosol-exposed proteins to manipulate the host immune response.

    Directory of Open Access Journals (Sweden)

    Yaakov Maman

    2011-10-01

    Full Text Available The main adaptive immune response to bacteria is mediated by B cells and CD4+ T-cells. However, some bacterial proteins reach the cytosol of host cells and are exposed to the host CD8+ T-cells response. Both gram-negative and gram-positive bacteria can translocate proteins to the cytosol through type III and IV secretion and ESX-1 systems, respectively. The translocated proteins are often essential for the bacterium survival. Once injected, these proteins can be degraded and presented on MHC-I molecules to CD8+ T-cells. The CD8+ T-cells, in turn, can induce cell death and destroy the bacteria's habitat. In viruses, escape mutations arise to avoid this detection. The accumulation of escape mutations in bacteria has never been systematically studied. We show for the first time that such mutations are systematically present in most bacteria tested. We combine multiple bioinformatic algorithms to compute CD8+ T-cell epitope libraries of bacteria with secretion systems that translocate proteins to the host cytosol. In all bacteria tested, proteins not translocated to the cytosol show no escape mutations in their CD8+ T-cell epitopes. However, proteins translocated to the cytosol show clear escape mutations and have low epitope densities for most tested HLA alleles. The low epitope densities suggest that bacteria, like viruses, are evolutionarily selected to ensure their survival in the presence of CD8+ T-cells. In contrast with most other translocated proteins examined, Pseudomonas aeruginosa's ExoU, which ultimately induces host cell death, was found to have high epitope density. This finding suggests a novel mechanism for the manipulation of CD8+ T-cells by pathogens. The ExoU effector may have evolved to maintain high epitope density enabling it to efficiently induce CD8+ T-cell mediated cell death. These results were tested using multiple epitope prediction algorithms, and were found to be consistent for most proteins tested.

  4. Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils

    OpenAIRE

    Aanniz,Tarik; Ouadghiri,Mouna; Melloul,Marouane; Swings,Jean; Elfahime,Elmostafa; Ibijbijen,Jamal; Ismaili,Mohamed; Amar,Mohamed

    2015-01-01

    The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. ...

  5. Imported anthropogenic bacteria may survive the Antarctic winter and introduce new genes into local bacterial communities

    OpenAIRE

    Brat Kristian; Sedlacek Ivo; Sevcikova Alena; Merta Zdenek; Laska Kamil; Sevcik Pavel

    2016-01-01

    We studied dynamic changes in anthropogenic bacterial communities at a summer-operated Czech research base (the Mendel Research Station) in the Antarctic during 2012 and 2013. We observed an increase in total numbers of detected bacteria between the beginning and the end of each stay in the Antarctic. In the first series of samples, bacteria of Bacillus sp. predominated. Surprisingly, high numbers of Gram-positive cocci and coliforms were found (including opportunistic human pathogens), altho...

  6. Micro-Raman spectroscopy for identification and classification of UTI bacteria

    Science.gov (United States)

    Yogesha, M.; Chawla, Kiran; Acharya, Mahendra; Chidangil, Santhosh; Bankapur, Aseefhali

    2017-07-01

    Urinary tract infection (UTI) is one of the major clinical problems known to mankind, especially among adult women. Conventional methods for identification of UTI causing bacteria are time consuming and expensive. Therefore, a rapid and cost-effective method is desired. In the present study, five bacteria (one Gram-positive and four Gram-negative), most commonly known to cause UTI, have been identified and classified using micro-Raman spectroscopy combined with principal component analysis (PCA).

  7. Copper sulfate pentahydrate reduced epithelial cytotoxicity induced by lipopolysaccharide from enterogenic bacteria.

    Science.gov (United States)

    Feyzi, Adel; Delkhosh, Aref; Nasrabadi, Hamid Tayefi; Cheraghi, Omid; Khakpour, Mansour; Barekati-Mowahed, Mazyar; Soltani, Sina; Mohammadi, Seyede Momeneh; Kazemi, Masoumeh; Hassanpour, Mehdi; Rezabakhsh, Aysa; Maleki-Dizaji, Nasrin; Rahbarghazi, Reza; Namdarian, Reza

    2017-05-01

    The over usage of multiple antibiotics contributes to the emergence of a whole range of antibiotic-resistant strains of bacteria causing enterogenic infections in poultry science. Therefore, finding an appropriate alternative natural substance carrying an antibacterial capacity would be immensely beneficial. It has been previously discovered that the different types of cupric salts, especially copper sulfate pentahydrate (CuSO 4 ·5H 2 O), to carry a potent bactericidal capacity. We investigated the neutralizing effect of CuSO 4 ·5H 2 O (6.25μg/ml) on the reactive oxygen species generation, and expression of MyD88, an essential adaptor protein of Toll-like receptor, and NF-κB in three intestinal epithelial cell lines exposed to 50ng/ml lipopolysaccharide. In order to find the optimal cupric sulfate concentration without enteritis-inducing toxicity, broiler chickens were initially fed with water containing 0.4, 0.5, and 1mg/l during a period of 4days. After determination of appropriate dosage, two broiler chickens and turkey flocks with enteritis were fed with cupric compound for 4days. We found that cupric sulfate can lessen the cytotoxic effect of lipopolysaccharide by reducing the reactive oxygen species content (psulfate. The copper sulfate in doses lower than 0.4mg/ml expressed no cytotoxic effect on the liver, kidney, and the intestinal tract while a concentration of 0.5 and 1mg/ml contributed to a moderate to severe tissue injuries. Pearson Chi-Square analysis revealed the copper cation significantly diminished the rate of mortality during 4-day feeding of broiler chicken and turkey with enteritis (p=0.000). Thus, the results briefed above all confirm the potent anti-bactericidal feature of cupric sulfate during the course of enteritis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  8. Perturbation of gut bacteria induces a coordinated cellular immune response in the purple sea urchin larva

    Science.gov (United States)

    CH Ho, Eric; Buckley, Katherine M; Schrankel, Catherine S; Schuh, Nicholas W; Hibino, Taku; Solek, Cynthia M; Bae, Koeun; Wang, Guizhi; Rast, Jonathan P

    2016-01-01

    The purple sea urchin (Strongylocentrotus purpuratus) genome sequence contains a complex repertoire of genes encoding innate immune recognition proteins and homologs of important vertebrate immune regulatory factors. To characterize how this immune system is deployed within an experimentally tractable, intact animal, we investigate the immune capability of the larval stage. Sea urchin embryos and larvae are morphologically simple and transparent, providing an organism-wide model to view immune response at cellular resolution. Here we present evidence for immune function in five mesenchymal cell types based on morphology, behavior and gene expression. Two cell types are phagocytic; the others interact at sites of microbial detection or injury. We characterize immune-associated gene markers for three cell types, including a perforin-like molecule, a scavenger receptor, a complement-like thioester-containing protein and the echinoderm-specific immune response factor 185/333. We elicit larval immune responses by (1) bacterial injection into the blastocoel and (2) seawater exposure to the marine bacterium Vibrio diazotrophicus to perturb immune state in the gut. Exposure at the epithelium induces a strong response in which pigment cells (one type of immune cell) migrate from the ectoderm to interact with the gut epithelium. Bacteria that accumulate in the gut later invade the blastocoel, where they are cleared by phagocytic and granular immune cells. The complexity of this coordinated, dynamic inflammatory program within the simple larval morphology provides a system in which to characterize processes that direct both aspects of the echinoderm-specific immune response as well as those that are shared with other deuterostomes, including vertebrates. PMID:27192936

  9. BACILLUS-METHANOLICUS SP-NOV, A NEW SPECIES OF THERMOTOLERANT, METHANOL-UTILIZING, ENDOSPORE-FORMING BACTERIA

    NARCIS (Netherlands)

    ARFMAN, N; DIJKHUIZEN, L; KIRCHHOF, G; LUDWIG, W; SCHLEIFER, KH; BULYGINA, ES; CHUMAKOV, KM; GOVORUKHINA, NI; TROTSENKO, YA; WHITE, D; SHARP, RJ

    The generic position of 14 strains of gram-positive bacteria able to use methanol as a growth substrate was determined. All are obligately aerobic, thermotolerant organisms that are able to grow at temperatures of 35 to 60-degrees-C. Nine of the strains produce oval spores at a

  10. Functional properties of nisin-carbohydrate conjugates formed by radiation induced Maillard reaction

    Science.gov (United States)

    Muppalla, Shobita R.; Sonavale, Rahul; Chawla, Surinder P.; Sharma, Arun

    2012-12-01

    Nisin-carbohydrate conjugates were prepared by irradiating nisin either with glucose or dextran. Increase in browning and formation of intermediate products was observed with a concomitant decrease in free amino and reducing sugar groups indicating occurrence of the Maillard reaction catalyzed by irradiation. Nisin-carbohydrate conjugates showed a broad spectrum antibacterial activity against Gram negative bacteria (Escherichia coli, Pseudomonas fluorescence) as well as Gram positive bacteria (Staphylococcus aureus, Bacillus cereus). Results of antioxidant assays, including that of DPPH radical-scavenging activity and reducing power, showed that the nisin-dextran conjugates possessed better antioxidant potential than nisin-glucose conjugate. These results suggested that it was possible to enhance the functional properties of nisin by preparing radiation induced conjugates suitable for application in food industry.

  11. Acid-regulated proteins induced by Streptococcus mutans and other oral bacteria during acid shock.

    Science.gov (United States)

    Hamilton, I R; Svensäter, G

    1998-10-01

    first 30 min of the acid shock, with a total of 11 acid-regulated proteins formed during the 2-h adaptation period with enhanced synthesis transient for seven of these proteins. Streptococcus salivarius AT2 and Streptococcus gordonii TH12 had the formation of 6 and 8 proteins enhanced, while the weakly responding organisms, Streptococcus sanguis ATCC 10,556 and Streptococcus oralis ATCC 10,557, exhibited 8 and 6 such proteins, respectively. Even non-responding strains unable to survive at very low pH, such as Streptococcus sobrinus CH125/43, Streptococcus mitis ATCC 12,261 and Actinomyces naeslundii 301-13 showed the initial formation of 3-9 acid-regulated proteins, but protein synthesis was not sustained over the entire adaptation period. Clearly, the survival of oral bacteria at very low pH is related, not to the total number of the acid-regulated proteins induced per se but to the formation of key proteins that function to augment normal pH homeostasis.

  12. Modulation of pathogen-induced CCL20 secretion from HT-29 human intestinal epithelial cells by commensal bacteria.

    LENUS (Irish Health Repository)

    Sibartie, Shomik

    2009-01-01

    BACKGROUND: Human intestinal epithelial cells (IECs) secrete the chemokine CCL20 in response to infection by various enteropathogenic bacteria or exposure to bacterial flagellin. CCL20 recruits immature dendritic cells and lymphocytes to target sites. Here we investigated IEC responses to various pathogenic and commensal bacteria as well as the modulatory effects of commensal bacteria on pathogen-induced CCL20 secretion. HT-29 human IECs were incubated with commensal bacteria (Bifidobacterium infantis or Lactobacillus salivarius), or with Salmonella typhimurium, its flagellin, Clostridium difficile, Mycobacterium paratuberculosis, or Mycobacterium smegmatis for varying times. In some studies, HT-29 cells were pre-treated with a commensal strain for 2 hr prior to infection or flagellin stimulation. CCL20 and interleukin (IL)-8 secretion and nuclear factor (NF)-kappaB activation were measured using enzyme-linked immunosorbent assays. RESULTS: Compared to untreated cells, S. typhimurium, C. difficile, M. paratuberculosis, and flagellin activated NF-kappaB and stimulated significant secretion of CCL20 and IL-8 by HT-29 cells. Conversely, B. infantis, L. salivarius or M. smegmatis did not activate NF-kappaB or augment CCL20 or IL-8 production. Treatment with B. infantis, but not L. salivarius, dose-dependently inhibited the baseline secretion of CCL20. In cells pre-treated with B. infantis, C. difficile-, S. typhimurium-, and flagellin-induced CCL20 were significantly attenuated. B. infantis did not limit M. Paratuberculosis-induced CCL20 secretion. CONCLUSION: This study is the first to demonstrate that a commensal strain can attenuate CCL20 secretion in HT-29 IECs. Collectively, the data indicate that M. paratuberculosis may mediate mucosal damage and that B. infantis can exert immunomodulatory effects on IECs that mediate host responses to flagellin and flagellated enteric pathogens.

  13. Contaminant bacteria in traditional-packed honey

    Directory of Open Access Journals (Sweden)

    Hening Tjaturina Pramesti

    2007-03-01

    Full Text Available Honey may be contaminated by microorganisms during its harvesting, processing, and packaging. Honey selected for clinical purposes must safe, sterile, and contain antimicrobial activity, so it must be evaluated using laboratory testing. The aim of this descriptive laboratory study was to isolate and identify the bacterial contaminant in the traditional-packed honey dealing with the use of honey for medical purposes. the colony forming units of honey sample cultured on blood agar were counted using Stuart bacterial colony counter. The suspected bacterial colonies were isolated and identified based on cultural morphology characteristics. The isolates of suspected bacterial colonies were stained according to Gram and Klein method and then were examined by the biochemical reaction. The results showed that there were two contaminant bacteria. Gram-positive cocci which were presumptively identified as coagulase-negative Staphylococci and gram-positive rods which were presumptively identified as Bacillus subtilis. In conclusion, the contaminant bacteria were regarded as low pathogen bacteria. The subtilin enzyme of B subtilis may cause an allergic reaction and coagulase-negative Staphylococci, Staphylococcus epidermidis is also an opportunist pathogen. Inevitably, for medical purposes, traditional-packed honey must be well filtered, water content above 18%, and standardized sterilization without loss of an antibacterial activity or change in properties.

  14. Bacteria-induced morphogenesis of Ulva intestinalis and Ulva mutabilis (Chlorophyta): a contribution to the lottery theory.

    Science.gov (United States)

    Ghaderiardakani, Fatemeh; Coates, Juliet C; Wichard, Thomas

    2017-08-01

    The green marine macroalgae of the class Ulvophyceae (Ulvophytes) are common algae distributed worldwide particularly in intertidal areas, which play a key role in aquatic ecosystems. They are potentially valuable resources for food, animal feed and fuel but can also cause massive nuisance blooms. Members of Ulvaceae, like many other seaweeds, harbour a rich diversity of epiphytic bacteria with functions related to host growth and morphological development. In the absence of appropriate bacterially derived signals, germ cells of the genus Ulva develop into 'atypical' colonies consisting of undifferentiated cells with abnormal cell walls. This paper examines the specificity of bacteria-induced morphogenesis in Ulva, by cross-testing bacteria isolated from several Ulva species on two Ulva species, the emerging model system Ulva mutabilis and the prominent biofouler species Ulva intestinalis. We show that pairs of bacterial strains isolated from species other than U. mutabilis and U. intestinalis can fully rescue axenic plantlets generated either from U. mutabilis or U. intestinalis gametes. This laboratory-based study demonstrates that different compositions of microbial communities with similar functional characteristics can enable complete algal morphogenesis and thus supports the 'competitive lottery' theory for how symbiotic bacteria drive algal development. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Simultaneous fluorescent gram staining and activity assessment of activated sludge bacteria.

    Science.gov (United States)

    Forster, Scott; Snape, Jason R; Lappin-Scott, Hilary M; Porter, Jonathan

    2002-10-01

    Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that the relative proportions of gram-positive and gram-negative bacterial cells identified by traditional microscopy and hexidium iodide staining were not significantly different. Dual staining of cells for Gram status and activity proved effective in analyzing mixtures of cultured bacteria and wastewater populations. Levels of highly active organisms at two wastewater treatment plants, both gram positive and gram negative, ranged from 1.5% in activated sludge flocs to 16% in the activated sludge fluid. Gram-positive organisms comprised Gram status and activity within activated sludge samples over a 4-day period showed significant differences over time. This method provides a rapid, quantitative measure of Gram status linked with in situ activity within wastewater systems.

  16. Discovery of novel cell wall-active compounds using P ywaC, a sensitive reporter of cell wall stress, in the model gram-positive bacterium Bacillus subtilis.

    Science.gov (United States)

    Czarny, T L; Perri, A L; French, S; Brown, E D

    2014-06-01

    The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  17. Enhance wastewater biological treatment through the bacteria induced graphene oxide hydrogel.

    Science.gov (United States)

    Shen, Liang; Jin, Ziheng; Wang, Dian; Wang, Yuanpeng; Lu, Yinghua

    2018-01-01

    The interaction between bacteria and graphene-family materials like pristine graphene, graphene oxide (GO) and reduced graphene oxide (rGO) is such an elusive issue that its implication in environmental biotechnology is unclear. Herein, two kinds of self-assembled bio-rGO-hydrogels (BGHs) were prepared by cultivating specific Shewanella sp. strains with GO solution for the first time. The microscopic examination by SEM, TEM and CLSM indicated a porous 3D structure of BGHs, in which live bacteria firmly anchored and extracellular polymeric substances (EPS) abundantly distributed. Spectra of XRD, FTIR, XPS and Raman further proved that GO was reduced to rGO by bacteria along with the gelation process, which suggests a potential green technique to produce graphene. Based on the characterization results, four mechanisms for the BGH formation were proposed, i.e., stacking, bridging, rolling and cross-linking of rGO sheets, through the synergistic effect of activities and EPS from special bacteria. More importantly, the BGHs obtained in this study were found able to achieve unique cleanup performance that the counterpart free bacteria could not fulfill, as exemplified in Congo red decolorization and Cr(VI) bioreduction. These findings therefore enlighten a prospective application of graphene materials for the biological treatment of wastewaters in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Assessment of airborne bacteria in selected occupational environments in Quezon City, Philippines.

    Science.gov (United States)

    Rendon, Rhoshela Vi C; Garcia, Bea Clarise B; Vital, Pierangeli G

    2017-05-04

    Exposure to bioaerosols has been associated with health deterioration among workers in several occupational environments. This highlights the need to study the microbiological quality of air of workplaces as no such study has been conducted yet in the Philippines. To detect and characterize the culturable mesophilic airborne bacteria in selected occupational environments we used passive sedimentation technique. It was observed that the number of colony-forming units was highest in junk shop, followed by the light railway transit station and last the office. By contrast, the bacterial composition was similar in all sites: Gram-positive cocci > Gram-positive bacilli > Gram-negative bacteria. Staphylococcus aureus and Bacillus spp. were also detected in all sites. These findings suggest that the presence of airborne bacteria may be a potential health hazard in urban occupational environments in the Philippines.

  19. Phytoplasmas: bacteria that manipulate plants and insects.

    Science.gov (United States)

    Hogenhout, Saskia A; Oshima, Kenro; Ammar, El-Desouky; Kakizawa, Shigeyuki; Kingdom, Heather N; Namba, Shigetou

    2008-07-01

    Superkingdom Prokaryota; Kingdom Monera; Domain Bacteria; Phylum Firmicutes (low-G+C, Gram-positive eubacteria); Class Mollicutes; Candidatus (Ca.) genus Phytoplasma. Ca. Phytoplasma comprises approximately 30 distinct clades based on 16S rRNA gene sequence analyses of approximately 200 phytoplasmas. Phytoplasmas are mostly dependent on insect transmission for their spread and survival. The phytoplasma life cycle involves replication in insects and plants. They infect the insect but are phloem-limited in plants. Members of Ca. Phytoplasma asteris (16SrI group phytoplasmas) are found in 80 monocot and dicot plant species in most parts of the world. Experimentally, they can be transmitted by approximately 30, frequently polyphagous insect species, to 200 diverse plant species. In plants, phytoplasmas induce symptoms that suggest interference with plant development. Typical symptoms include: witches' broom (clustering of branches) of developing tissues; phyllody (retrograde metamorphosis of the floral organs to the condition of leaves); virescence (green coloration of non-green flower parts); bolting (growth of elongated stalks); formation of bunchy fibrous secondary roots; reddening of leaves and stems; generalized yellowing, decline and stunting of plants; and phloem necrosis. Phytoplasmas can be pathogenic to some insect hosts, but generally do not negatively affect the fitness of their major insect vector(s). In fact, phytoplasmas can increase fecundity and survival of insect vectors, and may influence flight behaviour and plant host preference of their insect hosts. The most common practices are the spraying of various insecticides to control insect vectors, and removal of symptomatic plants. Phytoplasma-resistant cultivars are not available for the vast majority of affected crops.

  20. Bacterial feeding, Leishmania infection and distinct infection routes induce differential defensin expression in Lutzomyia longipalpis.

    Science.gov (United States)

    Telleria, Erich L; Sant'Anna, Maurício R Viana; Alkurbi, Mohammad O; Pitaluga, André N; Dillon, Rod J; Traub-Csekö, Yara M

    2013-01-11

    Phlebotomine insects harbor bacterial, viral and parasitic pathogens that can cause diseases of public health importance. Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the New World. Insects can mount a powerful innate immune response to pathogens. Defensin peptides take part in this response and are known to be active against Gram-positive and Gram-negative bacteria, and some parasites. We studied the expression of a defensin gene from Lutzomyia longipalpis to understand its role in sand fly immune response. We identified, sequenced and evaluated the expression of a L. longipalpis defensin gene by semi-quantitative RT-PCR. The gene sequence was compared to other vectors defensins and expression was determined along developmental stages and after exposure of adult female L. longipalpis to bacteria and Leishmania. Phylogenetic analysis showed that the L. longipalpis defensin is closely related to a defensin from the Old World sand fly Phlebotomus duboscqi. Expression was high in late L4 larvae and pupae in comparison to early larval stages and newly emerged flies. Defensin expression was modulated by oral infection with bacteria. The Gram-positive Micrococcus luteus induced early high defensin expression, whilst the Gram-negative entomopathogenic Serratia marcescens induced a later response. Bacterial injection also induced defensin expression in adult insects. Female sand flies infected orally with Leishmania mexicana showed no significant difference in defensin expression compared to blood fed insects apart from a lower defensin expression 5 days post Leishmania infection. When Leishmania was introduced into the hemolymph by injection there was no induction of defensin expression until 72 h later. Our results suggest that L. longipalpis modulates defensin expression upon bacterial and Leishmania infection, with patterns of expression that are distinct among bacterial species and routes of infection.

  1. A flow-cytometric gram-staining technique for milk-associated bacteria.

    Science.gov (United States)

    Holm, Claus; Jespersen, Lene

    2003-05-01

    A Gram-staining technique combining staining with two fluorescent stains, Oregon Green-conjugated wheat germ agglutinin (WGA) and hexidium iodide (HI) followed by flow-cytometric detection is described. WGA stains gram-positive bacteria while HI binds to the DNA of all bacteria after permeabilization by EDTA and incubation at 50 degrees C for 15 min. For WGA to bind to gram-positive bacteria, a 3 M potassium chloride solution was found to give the highest fluorescence intensity. A total of 12 strains representing some of the predominant bacterial species in bulk tank milk and mixtures of these were stained and analyzed by flow cytometry. Overall, the staining method showed a clear differentiation between gram-positive and gram-negative bacterial populations. For stationary-stage cultures of seven gram-positive bacteria and five gram-negative bacteria, an average of 99% of the cells were correctly interpreted. The method was only slightly influenced by the growth phase of the bacteria or conditions such as freezing at -18 degrees C for 24 h. For any of these conditions, an average of at least 95% of the cells were correctly interpreted. When stationary-stage cultures were stored at 5 degrees C for 14 days, an average of 86% of the cells were correctly interpreted. The Gram-staining technique was applied to the flow cytometry analysis of bulk tank milk inoculated with Staphylococcus aureus and Escherichia coli. These results demonstrate that the technique is suitable for analyzing milk samples without precultivation.

  2. Cell Size Regulation in Bacteria

    Science.gov (United States)

    Amir, Ariel

    2014-05-01

    Various bacteria such as the canonical gram negative Escherichia coli or the well-studied gram positive Bacillus subtilis divide symmetrically after they approximately double their volume. Their size at division is not constant, but is typically distributed over a narrow range. Here, we propose an analytically tractable model for cell size control, and calculate the cell size and interdivision time distributions, as well as the correlations between these variables. We suggest ways of extracting the model parameters from experimental data, and show that existing data for E. coli supports partial size control, and a particular explanation: a cell attempts to add a constant volume from the time of initiation of DNA replication to the next initiation event. This hypothesis accounts for the experimentally observed correlations between mother and daughter cells as well as the exponential dependence of size on growth rate.

  3. protective and therapeutic effects of anaerobic bacteria sonicate on experimentally induced intestinal inflammation

    Czech Academy of Sciences Publication Activity Database

    Sokol, Dan; Rossmann, Pavel; Jelen, P.; Hudcovic, Tomáš; Horáková, Dana; Jelínková, Lenka; Tučková, Ludmila; Tlaskalová, Helena

    2003-01-01

    Roč. 87, č. 1 (2003), s. 87 ISSN 0165-2478. [European Immunology Congress /15./. Rhodes, 08.06.2003-12.06.2003] Institutional research plan: CEZ:AV0Z5020903 Keywords : anacrobic * bacteria * sonicate Subject RIV: EE - Microbiology, Virology Impact factor: 1.710, year: 2003

  4. High-level iron mitigates fusaricidin-induced membrane damage and reduces membrane fluidity leading to enhanced drug resistance in Bacillus subtilis.

    Science.gov (United States)

    Yu, Wen-Bang; Ye, Bang-Ce

    2016-05-01

    Fusaricidins are a class of cyclic lipopeptide antibiotics that have strong antifungal activities against plant pathogenic fungi and excellent bactericidal activities against Gram-positive bacteria. The mechanism through which fusaricidin exerts its action is not yet entirely clear. To investigate the mode of action of fusaricidin, we determined the physiological and transcriptional responses of Bacillus subtilis to fusaricidin treatment by using a systems-level approach. Our data show that fusaricidin rapidly induced the expression of σ(W) regulon and caused membrane damage in B. subtilis. We further demonstrated that ferric ions play multiple roles in the action of fusaricidin on B. subtilis. Iron deprivation blocked the formation of hydroxyl radical in the cells and significantly inhibited the bactericidal activity of fusaricidin. Conversely, high levels of iron (>2 mM) repressed the expression of BkdR regulon, resulting in a smaller cellular pool of branched-chain precursors for iso- and anteiso-branched fatty acids, which in turn led to a decrease in the proportion of branched-chain fatty acids in the membrane of B. subtilis. This change in membrane composition reduced its bilayer fluidity and increased its resistance to antimicrobial agents. In conclusion, our experiments uncovered some novel interactions and a synergism between cellular iron levels and drug resistance in Gram-positive bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Microbiological Synthesis of 2H-Labeled Phenylalanine, Alanine, Valine, and Leucine/Isoleucine with Different Degrees of Deuterium Enrichment by the Gram-Positive Facultative Methylotrophic Bacterium Вrevibacterium Methylicum

    Directory of Open Access Journals (Sweden)

    Oleg V. Mosin, PhD¹

    2013-06-01

    Full Text Available The microbiological synthesis of [2H]amino acids was performed by the conversion of low molecular weight substrates ([U-2H]MeOH and 2H2O using the Gram-positive aerobic facultative methylotrophic bacterium Brevibacterium methylicum, an L-phenylalanine producer, realizing the NAD+ dependent methanol dehydrogenase (EC 1.6.99.3 variant of the ribulose-5-monophosphate (RuMP cycle of carbon assimilation. In this process, the adapted cells of the methylotroph with enhanced growth characteristics were used on a minimal salt medium M9, supplemented with 2% (v/v [U-2H]MeOH and an increasing gradient of 2Н2O concentration from 0; 24.5, 49.0; 73.5 up to 98% (v/v 2Н2O. Alanine, valine, and leucine/isoleucine were produced and accumulated exogeneously in quantities of 5–6 mol, in addition to the main product of biosynthesis. This method enables the production of [2Н]amino acids with different degrees of deuterium enrichment, depending on the 2Н2O concentration in the growth medium, from 17 at.% 2Н (on the growth medium with 24.5 % (v/v 2Н2О up to 75 at.% 2Н (on the growth medium with 98 % (v/v 2Н2О. This has been confirmed with the data from the electron impact (EI mass spectrometry analysis of the methyl ethers of N-dimethylamino(naphthalene-5-sulfochloride [2H]amino acids under these experimental conditions.

  6. THE ROLE OF RED PIGMENT PRODIGIOSIN FROM BACTERIA OF EARTHWORM GUT AS AN ANTICANCER AGENT

    Directory of Open Access Journals (Sweden)

    Sruthy P.B.

    2014-12-01

    Full Text Available Earthworms are the most ancient invertebrate animals on earth which can be used as a good source of pharmaceutical compounds. A study was carried out to find out the distribution of microorganisms in the gut of earthworm, Eudrilus eugeniae. Significant number of microbial populations in the gut of earthworm was observed and it was gradually increased from the initial day to final day of composting. Pigmented colonies of bacteria from earthworm gut were selectively isolated, the pigment was extracted from the culture broth and a presumptive test was carried out for the confirmation of prodigiosin. The pigment component was separated using thin layer chromatography and the structural elucidation of the compound was performed using U.V. spectroscopy. The inhibitory effect of prodigiosin on bacterial pathogens was studied and the results confirmed the antibacterial activity against gram positive bacteria. The anticancer activity of the prodigiosin pigment was evaluated under in vitro conditions against the breast cancer cell lines and it was observed that prodigiosin induced the apoptosis in MCF-7 cell lines in a dose dependent manner. Then the potential isolate was subjected to morphological and biochemical analysis and it was confirmed that the colonies were of Serratia marcescens. The results obtained from the present study indicated that earthworm gut is promising and could be a vital source of habitat possessing antimicrobial and anticancer activity.

  7. Dendritic Cells from Peyer's Patches and Mesenteric Lymph Nodes Differ from Spleen Dendritic Cells in their Response to Commensal Gut Bacteria

    DEFF Research Database (Denmark)

    Fink, Lisbeth Nielsen; Frøkiær, Hanne

    2008-01-01

    . Expression of CCR7 and CD103 on the surface of MLN DC, necessary for the induction of gut-homing regulatory T cells, increased with stimulation by Gram-positive commensals. Bacteria-dependent cytokine production (IL-6, IL-10 and TNF-alpha) was similar in spleen and MLN DC, and contaminant cells in these DC...

  8. Antimicrobial Peptides: a promising class of antimicrobial compounds against BWA and multi-drug resistant bacteria: in the spotlight: the lactoferrin chimera

    NARCIS (Netherlands)

    Bikker, F.J.; Sijbrandij, T.; Nazmi, K.; Bolscher, J.G.M.; Veerman, E.C.I.; Jansen, H-J.

    2014-01-01

    Anti-Microbial Peptides (AMPs) are part of the innate immune defense system and considered as promising lead compounds for the development of novel anti-bacterial agents. In general, AMPs are simple, short peptides with broad-spectrum activity against Gram-negative and Gram-positive bacteria, fungi,

  9. Vapor-induced transfer of bacteria in the absence of mechanical disturbances

    KAUST Repository

    Ayoub, George M.

    2014-09-01

    Transfer of bacteria through water vapor generated at moderate temperatures (30-50. °C) in passive solar stills, has scarcely been reported. The objective of this research was to investigate whether bacteria in highly humid atmospheres can get transferred through water vapor in the absence of other transfer media to find their way to the distillate. To achieve this objective, passive solar reactors were chosen as the medium for experimentation, and distillation experiments were conducted by spiking a pure bacterial culture (Escherichia coli, Klebsiella pneumonia or Enterococcus faecalis) in low mineralized water vs. highly mineralized water in the dark under moderate temperatures ranges (30-35. °C, 40-45. °C and 50-55. °C). Results showed that bacteria indeed get transferred with the vapor in stills when not exposed to solar U.V. radiation. The trends observed were adequately explained by a zero-modified Hurdle-Poisson model. The numbers of cultivable bacterial colonies transferred were bacterial size, water type and temperature dependent with highest transfers occurring in E. faecalis>. E. coli>. K. pneumonia at the 40. °C range in low mineralized water. Proper management strategies are recommended to achieve complete disinfection in solar stills. © 2014 Elsevier B.V.

  10. Differential activity of a lectin from Solieria filiformis against human pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    M.L. Holanda

    2005-12-01

    Full Text Available A lectin isolated from the red alga Solieria filiformis was evaluated for its effect on the growth of 8 gram-negative and 3 gram-positive bacteria cultivated in liquid medium (three independent experiments/bacterium. The lectin (500 µg/mL stimulated the growth of the gram-positive species Bacillus cereus and inhibited the growth of the gram-negative species Serratia marcescens, Salmonella typhi, Klebsiella pneumoniae, Enterobacter aerogenes, Proteus sp, and Pseudomonas aeruginosa at 1000 µg/mL but the lectin (10-1000 µg/mL had no effect on the growth of the gram-positive bacteria Staphylococcus aureus and B. subtilis, or on the gram-negative bacteria Escherichia coli and Salmonella typhimurium. The purified lectin significantly reduced the cell density of gram-negative bacteria, although no changes in growth phases (log, exponential and of decline were observed. It is possible that the interaction of S. filiformis lectin with the cell surface receptors of gram-negative bacteria promotes alterations in the flow of nutrients, which would explain the bacteriostatic effect. Growth stimulation of the gram-positive bacterium B. cereus was more marked in the presence of the lectin at a concentration of 1000 µg/mL. The stimulation of the growth of B. cereus was not observed when the lectin was previously incubated with mannan (125 µg/mL, its hapten. Thus, we suggest the involvement of the binding site of the lectin in this effect. The present study reports the first data on the inhibition and stimulation of pathogenic bacterial cells by marine alga lectins.

  11. Natural soil reservoirs for human pathogenic and fecal indicator bacteria

    Science.gov (United States)

    Boschiroli, Maria L; Falkinham, Joseph; Favre-Bonte, Sabine; Nazaret, Sylvie; Piveteau, Pascal; Sadowsky, Michael J.; Byappanahalli, Muruleedhara; Delaquis, Pascal; Hartmann, Alain

    2016-01-01

    Soils receive inputs of human pathogenic and indicator bacteria through land application of animal manures or sewage sludge, and inputs by wildlife. Soil is an extremely heterogeneous substrate and contains meso- and macrofauna that may be reservoirs for bacteria of human health concern. The ability to detect and quantify bacteria of human health concern is important in risk assessments and in evaluating the efficacy of agricultural soil management practices that are protective of crop quality and protective of adjacent water resources. The present chapter describes the distribution of selected Gram-positive and Gram-negative bacteria in soils. Methods for detecting and quantifying soilborne bacteria including extraction, enrichment using immunomagnetic capture, culturing, molecular detection and deep sequencing of metagenomic DNA to detect pathogens are overviewed. Methods for strain phenotypic and genotypic characterization are presented, as well as how comparison with clinical isolates can inform the potential for human health risk.

  12. Aerobic Bacteria in the Diaphragmatic Portion of Stethoscope of Medical Professionals of Tertiary Care Hospital.

    Science.gov (United States)

    Bham, G; Bhandari, J; Neupane, M R; Dawadi, R; Pradhan, P

    2015-01-01

    Hospital environment is a reservoir of wide varieties of microorganisms which are frequently reported colonizing in medical equipment. Stethoscopes are essential tools and of universal use in the medical profession, which might be a source of spreading nosocomial infections. This research project was conducted with an aim to assess the presence of aerobic bacteria in the stethoscope of the medical doctors working at Patan Hospital and students of Patan Academy of Health Sciences. It is a cross sectional study based on structured questionnaire and sample assessment from the stethoscope of doctors and students of Patan Hospital and Patan Academy of Health Sciences. The stethescopes used by the doctors of five major departments of Patan Hospital and students of clinical years were included in this study. Total of 99 stethoscope owned by different level of professionals (positions) and different departments were examined for bacterial contamination. Out of them, 36 were found to be considerably contaminated. Single strain of bacteria was grown from a single stethoscope. Among them 34 were Gram positive and remaining were Gram negative. Out of 34 gram postive bacteria, 29 were identified as Staphylococcus aureus, six were identified as Coagulase Negative Staphylococcus and remaining were Gram positive bacilli. There is presence of aerobic bacteria in diaphragmatic portion of stethoscope of medical professional of which the gram positives were the commonest.

  13. Matrix-assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) as a Reliable Tool to Identify Species of Catalase-negative Gram-positive Cocci not Belonging to the Streptococcus Genus.

    Science.gov (United States)

    Almuzara, Marisa; Barberis, Claudia; Velázquez, Viviana Rojas; Ramirez, Maria Soledad; Famiglietti, Angela; Vay, Carlos

    2016-01-01

    To evaluate the performance of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) by using 190 Catalase-negative Gram-Positive Cocci (GPC) clinical isolates. All isolates were identified by conventional phenotypic tests following the proposed scheme by Ruoff and Christensen and MALDI-TOF MS (Bruker Daltonics, BD, Bremen, Germany). Two different extraction methods (direct transfer formic acid method on spot and ethanol formic acid extraction method) and different cut-offs for genus/specie level identification were used. The score cut-offs recommended by the manufacturer (≥ 2.000 for species-level, 1.700 to 1.999 for genus level and genus level, ≥ 1.700 for species-level and score genus or species. MALDI-TOF MS identification was considered correct when the result obtained from MS database agreed with the phenotypic identification result. When both methods gave discordant results, the 16S rDNA or sodA genes sequencing was considered as the gold standard identification method. The results obtained by MS concordant with genes sequencing, although discordant with conventional phenotyping, were considered correct. MS results discordant with 16S or sod A identification were considered incorrect. Using the score cut-offs recommended by the manufacturer, 97.37% and 81.05% were correctly identified to genus and species level, respectively. On the other hand, using lower cut-off scores for identification, 97.89% and 94.21% isolates were correctly identified to genus and species level respectively by MALDI-TOF MS and no significant differences between the results obtained with two extraction methods were obtained. The results obtained suggest that MALDI-TOF MS has the potential of being an accurate tool for Catalase-negative GPC identification even for those species with difficult diagnosis as Helcococcus , Abiotrophia , Granulicatella , among others. Nevertheless, expansion of the library, especially including more strains with

  14. [Effect of vitamine A on mice immune response induced by specific periodontal pathogenic bacteria-immunization].

    Science.gov (United States)

    Lin, Xiao-Ping; Zhou, Xiao-Jia; Liu, Hong-Li; DU, Li-Li; Toshihisa, Kawai

    2010-12-01

    The aim of this study was to investigate the effect of vitamine-A deficiency on the induction of specific periodontal pathogenic bacteria A. actinomycetetemcomitans(Aa) immunization. BALB/c mice were fed with vitamine A-depleted diet or control regular diet throughout the whole experiment period. After 2 weeks, immunized formalin-killed Aa to build immunized models, 6 weeks later, sacrificed to determine specific antibody-IgG, IgM and sub-class IgG antibody titers in serum, and concentration of IL-10, IFN-γ, TNF-α and RANKL in T cell supernatant were measured by ELISA and T cell proliferation was measured by cintilography. SPSS 11.5 software package was used for statistical analysis. The levels of whole IgG and IgM antibody which were immunized by Aa significantly elevated, non-immune group was unable to produce any antibody. Compared with Aa immunized+RD group, the level of whole IgG in Aa immunized+VAD group was significantly higher (Pvitamin-A diet can increase the immunized mice's susceptibility to periodontal pathogenic bacteria and trigger or aggravate immune inflammatory response. Adequate vitamin A is an important factor in maintaining body health. Supported by Natural Science Foundation of Liaoning Province (Grant No.20092139) and Science and Technology Program of Shenyang Municipality (Grant No.F10-149-9-32).

  15. Trends of Bloodstream Infections in a University Greek Hospital during a Three-Year Period: Incidence of Multidrug-Resistant Bacteria and Seasonality in Gram-negative Predominance.

    Science.gov (United States)

    Kolonitsiou, Fevronia; Papadimitriou-Olivgeris, Matthaios; Spiliopoulou, Anastasia; Stamouli, Vasiliki; Papakostas, Vasileios; Apostolopoulou, Eleni; Panagiotopoulos, Christos; Marangos, Markos; Anastassiou, Evangelos D; Christofidou, Myrto; Spiliopoulou, Iris

    2017-07-06

    The aim of the study was to assess the epidemiology, the incidence of multidrug-resistant bacteria and bloodstream infections' (BSIs) seasonality in a university hospital. This retrospective study was carried out in the University General Hospital of Patras, Greece, during 2011-13 y. Blood cultures from patients with clinical presentation suggestive of bloodstream infection were performed by the BacT/ALERT System. Isolates were identified by Vitek 2 Advanced Expert System. Antibiotic susceptibility testing was performed by the disk diffusion method and E-test. Resistance genes (mecA in staphylococci; vanA/vanB/vanC in enterococci; bla KPC /bla VIM /bla NDM in Klebsiella spp.) were detected by PCR. In total, 4607 (9.7%) blood cultures were positive from 47451 sets sent to Department of Microbiology, representing 1732 BSIs. Gram-negative bacteria (52.3%) were the most commonly isolated, followed by Gram-positive (39.5%), fungi (6.6%) and anaerobes bacteria (1.8%). The highest contamination rate was observed among Gram-positive bacteria (42.3%). Among 330 CNS and 150 Staphylococcus aureus, 281 (85.2%) and 60 (40.0%) were mecA-positive, respectively. From 113 enterococci, eight were vanA, two vanB and two vanC-positives. Of the total 207 carbapenem-resistant Klebsiella pneumoniae (73.4%), 202 carried bla KPC , four bla KPC and bla VIM and one bla VIM . A significant increase in monthly BSIs' incidence was shown (R2: 0.449), which may be attributed to a rise of Gram-positive BSIs (R2: 0.337). Gram-positive BSIs were less frequent in spring (P period. The increasing incidence of BSIs can be attributed to an increase of Gram-positive BSI incidence, even though Gram-negative bacteria remained the predominant ones. Seasonality may play a role in the predominance of Gram-negative's BSI.

  16. Biological and structure-activity evaluation of chalcone derivatives against bacteria and fungi

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Wender A.; Andrade, Carlos Kleber Z.; Napolitano, Hamilton B., E-mail: wender@unb.br, E-mail: ckleber@unb.br [Universidade de Brasilia (LaQMOS/UnB), DF (Brazil). Inst. de Quimica; Vencato, Ivo; Castro, Miriam R.C. de; Camargo, Ademir J. [Universidade Estadual de Goias (UEG), Anapolis, GO (Brazil). Ciencias Exatas e Tecnologicas; Lariucci, Carlito [Universidade Estadual de Goias (UEG), Goiania, GO (Brazil). Inst. de Fisica

    2013-01-15

    The present work describes the antibacterial and antifungal activities of several chalcones obtained by a straight Claisen-Schmidt aldol condensation determined by the minimal inhibitory concentration against different microorganisms (Gram-positive and Gram-negative bacteria and fungi). Solid state crystal structures of seven chalcones were determined by X-ray diffraction (XRD) analysis. Chemometric studies were carried out in order to identify a potential structure activity relationship. (author)

  17. 16S RRNA Gene Analysis of Chlorate Reducing Thermophilic Bacteria From Local Hot Spring

    OpenAIRE

    Aminin, Agustina L. N; Katulistiwasari, Puri; Mulyani, Nies Suci

    2011-01-01

    Chlorates waste remediation by biological processes has been the object of current research. Strain CR, the chlorate reducing bacteria was isolated from Gedongsongo hot spring using minimal medium broth containing chlorates and acetate at 55oC. The determination of chlorate reduction from medium was carried out using turbidimetric method. CR isolate showed reducing ability 18% after four days of incubation. The phenotypic character of CR isolate including rod-shaped cells, gram-positive bacte...

  18. Sensitivity of spoiling and pathogen food-related bacteria to Origanum vulgare L. (Lamiaceae) essential oil

    OpenAIRE

    Souza,Evandro Leite de; Stamford,Tânia Lúcia Montenegro; Lima,Edeltrudes de Oliveira

    2006-01-01

    Origanum vulgare L. (oregano), Lamiaceae, has been known as plant specie with prominent biological properties for a long time. This study aimed to evaluate the antibacterial activity of Origanum vulgare essential oil on various Gram-positive and Gram-negative spoiling and/or pathogen food-related bacteria, as well as to observe its antimicrobial effectiveness in a food conservation micromodel. The results showed a strong antibacterial activity of the assayed essential oil noted by large growt...

  19. Metabolic response induced by endophytic fungi and bacteria in H. marrubioides Epling in vitro micro plants

    Energy Technology Data Exchange (ETDEWEB)

    Vitorino, Luciana Cristina; Silva, Fabiano Guimaraes, E-mail: fabianocefetrv@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia Goiano, Rio Verde, GO (Brazil); Lima, William Cardoso; Soares, Marcos Antonio [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Dept. de Botanica e Ecologia; Pedroso, Rita Cassia Nascimento; Silva, Maroli Rodrigues; Dias, Herbert Junior; Crotti, Antonio Eduardo Miller; Silva, Marcio Luis Andrade e; Cunha, Wilson Roberto; Pauletti, Patricia Mendonca; Januario, Ana Helena [Universidade de Franca, SP (Brazil). Nucleo de Pesquisa em Ciencias Exatas e Tecnologicas

    2013-10-01

    Hyptis marrubioides Epling is a native plant from Brazilian Cerrado. In this paper, the response of in vitro micro plants of this species to inoculation with bacterial and fungal endophytic isolates is evaluated. HPLC-DAD analysis showed the presence of 3,4-O-(Z)-dicaffeoylquinic acid and quercetin-7-O-glucoside as the main components. GC/MS analysis demonstrated that the sesquiterpenes Greek-Small-Letter-Tau -cadinol and caryophyllene oxide were only produced in micro plants inoculated with endophytic bacteria, while methyl hexadecanoate, methyl heptadecanoate and methyl (Z,Z,Z) 9,12,15-octadecatrienoate and the triterpene methyl 3{beta}-hydroxy-urs-12-en-28-oate were over expressed only when the micro plant was treated with endophytic fungi. (author)

  20. Metabolic response induced by endophytic fungi and bacteria in H. marrubioides Epling in vitro micro plants

    International Nuclear Information System (INIS)

    Vitorino, Luciana Cristina; Silva, Fabiano Guimaraes; Lima, William Cardoso; Soares, Marcos Antonio; Pedroso, Rita Cassia Nascimento; Silva, Maroli Rodrigues; Dias, Herbert Junior; Crotti, Antonio Eduardo Miller; Silva, Marcio Luis Andrade e; Cunha, Wilson Roberto; Pauletti, Patricia Mendonca; Januario, Ana Helena

    2013-01-01

    Hyptis marrubioides Epling is a native plant from Brazilian Cerrado. In this paper, the response of in vitro micro plants of this species to inoculation with bacterial and fungal endophytic isolates is evaluated. HPLC-DAD analysis showed the presence of 3,4-O-(Z)-dicaffeoylquinic acid and quercetin-7-O-glucoside as the main components. GC/MS analysis demonstrated that the sesquiterpenes τ-cadinol and caryophyllene oxide were only produced in micro plants inoculated with endophytic bacteria, while methyl hexadecanoate, methyl heptadecanoate and methyl (Z,Z,Z) 9,12,15-octadecatrienoate and the triterpene methyl 3β-hydroxy-urs-12-en-28-oate were over expressed only when the micro plant was treated with endophytic fungi. (author)

  1. Microbiological studies on petroleum and natural gas. I. Determination of hydrocarbon-utilizing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Iizuka, H; Komagata, K

    1964-01-01

    Hydrocarbon-utilizing bacteria were isolated from oil-brine, soils etc. sampled in oil fields in Japan during 1956, and the following species were identified: Corynebacterium hydrocarboclastus nov. sp., 11 strains; Pseudomonas nitroreducens nov. sp., 1 strain; Pseudomonas maltophila Hugh and Ryschenkow, 5 strains: Brevibacterium lipolyticum (Huss) Breed, 2 strains; Pseudomonas desmolytica Gray and Thornton, 5 strains; Flavobacterium ferrugineum Sickles and Shaw, 1 strain; and Alcaligenes faecalis Chastellani and Chalmers, 1 strain. One difference between Gram-negative bacteria and Gram-positive bacteria was described on the basis of the ability of assimilating hydrocarbons.

  2. Reduction of ferric iron by acidophilic heterotrophic bacteria: evidence for constitutive and inducible enzyme systems in Acidiphilium spp.

    Science.gov (United States)

    Johnson, D B; Bridge, T A M

    2002-01-01

    To compare the abilities of two obligately acidophilic heterotrophic bacteria, Acidiphilium acidophilum and Acidiphilium SJH, to reduce ferric iron to ferrous when grown under different culture conditions. Bacteria were grown in batch culture, under different aeration status, and in the presence of either ferrous or ferric iron. The specific rates of ferric iron reduction by fermenter-grown Acidiphilium SJH were unaffected by dissolved oxygen (DO) concentrations, while iron reduction by A. acidophilum was highly dependent on DO concentrations in the growth media. The ionic form of iron present (ferrous or ferric) had a minimal effect on the abilities of harvested cells to reduce ferric iron. Whole cell protein profiles of Acidiphilium SJH were very similar, regardless of the DO status of the growth medium, while additional proteins were present in A. acidophilum grown microaerobically compared with aerobically-grown cells. The dissimilatory reduction of ferric iron is constitutive in Acidiphilium SJH while it is inducible in A. acidophilum. Ferric iron reduction by Acidiphilium spp. may occur in oxygen-containing as well as anoxic acidic environments. This will detract from the effectiveness of bioremediation systems where removal of iron from polluted waters is mediated via oxidation and precipitation of the metal.

  3. Anaerobic bacteria

    Science.gov (United States)

    Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these bacteria ... Brook I. Diseases caused by non-spore-forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

  4. Detection of Beta-lactamase gene in the culturable bacteria isolated from agricultural, pasture and mining soils around mines in Hamedan, Iran

    Directory of Open Access Journals (Sweden)

    Nayereh Younessi

    2017-09-01

    Full Text Available Introduction: Growing evidence exists that agriculture affects antibiotic resistance in human pathogens. Beta-lactam antibiotics are the most commonly used antimicrobial agents in many countries. The abundance of beta-lactamase encoding genes can be used as an indicator of antibiotic resistance in the environment. So, to determine the beta-lactamase resistance genes, the abundance of culturable bacteria having bla-TEM genesin the soils under different land uses wasexamined. Materials and methods: 44 Gram-positive and 34 Gram-negative bacteria plated on nutrient agar were isolated from agricultural, pasture and mining soils and selected to study the presence of TEM-class gene using PCR amplification. Antibiotic sensitivity test of bla-TEM+isolateswas done adopting the Kirby-Bauer disk diffusion method and antibiotic discs used were: ampicillin, amoxicillin, vancomicin, streptomycin, tetracycline and gentamicin. Finally, five multi-drug resistant and bla-TEM+ isolates were identified using universal primers. Results: The highest level of beta-lactamase genes was observed in the Gram-positive and Gram-negative isolates from the pasture soils. In the agricultural and mining soils, a high abundance of bla-TEM+ isolateswasfound which also showed resistance to beta-lactam antibiotics. The identified multi-drug resistant and bla-TEM+ isolates were from these genera: Achromobacter, Bacillus, Brevibacillus, Aminobacter and Brevundimonas. Discussion and conclusion: The high number of bla-TEM+ bacteria in all the soils may be attributed to the other important feature of bla genes which is their capability to extrude toxic compounds like heavy metals in contaminated environments. Sensitivity of some bla-TEM+ bacteria to beta-lactam antibiotics was interesting. This result shows that bla-TEM genes confer resistance to beta-lactamase inhibitors in a different degree. Some of the identified isolates were pathogen. These pathogens in soils can transfer to plants

  5. Role of intestinal bacteria in gliadin-induced changes in intestinal mucosa: study in germ-free rats.

    Directory of Open Access Journals (Sweden)

    Jana Cinova

    Full Text Available BACKGROUND AND AIMS: Celiac disease (CD is a chronic inflammatory disorder of the small intestine that is induced by dietary wheat gluten proteins (gliadins in genetically predisposed individuals. The overgrowth of potentially pathogenic bacteria and infections has been suggested to contribute to CD pathogenesis. We aimed to study the effects of gliadin and various intestinal bacterial strains on mucosal barrier integrity, gliadin translocation, and cytokine production. METHODOLOGY/PRINCIPAL FINDINGS: Changes in gut mucosa were assessed in the intestinal loops of inbred Wistar-AVN rats that were reared under germ-free conditions in the presence of various intestinal bacteria (enterobacteria and bifidobacteria isolated from CD patients and healthy children, respectively and CD-triggering agents (gliadin and IFN-γ by histology, scanning electron microscopy, immunofluorescence, and a rat cytokine antibody array. Adhesion of the bacterial strains to the IEC-6 rat cell line was evaluated in vitro. Gliadin fragments alone or together with the proinflammatory cytokine interferon (IFN-γ significantly decreased the number of goblet cells in the small intestine; this effect was more pronounced in the presence of Escherichia coli CBL2 and Shigella CBD8. Shigella CBD8 and IFN-γ induced the highest mucin secretion and greatest impairment in tight junctions and, consequently, translocation of gliadin fragments into the lamina propria. Shigella CBD8 and E. coli CBL2 strongly adhered to IEC-6 epithelial cells. The number of goblet cells in small intestine increased by the simultaneous incubation of Bifidobacterium bifidum IATA-ES2 with gliadin, IFN-γ and enterobacteria. B. bifidum IATA-ES2 also enhanced the production of chemotactic factors and inhibitors of metalloproteinases, which can contribute to gut mucosal protection. CONCLUSIONS: Our results suggest that the composition of the intestinal microbiota affects the permeability of the intestinal mucosa

  6. Effect of henna and roselle extracts on pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Rafat Khalaphallah

    2014-08-01

    Full Text Available Objective: To investigate the antibacterial effects of water and ethanolic extracts of henna leaves and roselle calyxes against pathogenic bacteria isolated from domestic wastewater. Methods: The antimicrobial activity was determined in the extracts using agar disc diffusion method. The antibacterial activities of extracts (2.5%, 5.0% and 10.0% w/v of both henna and roselle were tested against one Gram-positive Bacillius subtilis; two Gram-negative Escherichia coli, Pseudomonas aeruginosa human pathogenic bacteria. Results: Ethanolic extracts had more antimicrobial activity than water extracts. Ethanolic extract of roselle had the highest antibacterial activity against all tested organisms, followed with ethanolic extract of henna. Pseudomonas aeruginosa was the most sensitive bacteria to plant extracts. Conclusion: The results of this study suggested that roselle contains more phyto-chemicals with antimicrobial activity than henna on the bacteria strains under study, and these phyto-chemicals were more effective when extracted by ethanol rather than water.

  7. Perfil de susceptibilidade a antimicrobianos em amostras de cocos Gram-positivos, catalase negativos, isoladas de mastite subclínica bubalina Profile of antimicrobial susceptibility in strains of Gram positive cocos, negative catalase, isolated from buffalo subclinical mastitis

    Directory of Open Access Journals (Sweden)

    Maria C.E. Vianni

    2003-06-01

    Full Text Available Estudou-se o perfil de susceptibilidade a antimicrobianos em cocos Gram-positivos catalase negativos (21 amostras de Lactococcus garvieae e 6 de Enterococcus gallinarum, isoladas do leite de fêmeas com mastite subclínica e pertencentes a uma população composta por seis rebanhos bubalinos localizados no Estado do Rio de Janeiro. O teste utilizado foi o da difusão de discos em agar Müller Hinton, segundo recomendações do National Committee for Clinical Laboratory Standards - NCCLS, tendo sido testados discos com ampicilina (10mg, cefalotina (30mg, cefotaxima (30mg, cefoxitina (30mg, cloranfenicol (30mg, eritromicina (15mg, gentamicina (10mg, nitrofurantoína (300mg, norfloxacina (10mg, penicilina (10 UI, tetraciclina (30mg e vancomicina (30mg. Os resultados evidenciaram que em se tratando de Lactococcus garvieae, o antimicrobiano mais eficiente foi o nitrofurantoína com 85,71% de sensibilidade, seguido da cefotaxima (61,90%, vancomicina (52,38%, norfloxacina (47,62% e cefalotina (47,62%. A maior resistência foi desenvolvida frente a penicilina e ampicilina, com 95,24% de resistênciapara os dois antimicrobianos testados. O perfil de susceptibilidade desenvolvido pelas amostras de Enterococcus gallinarum, mostrou baixa sensibilidade frente aos antimicrobianos testados, onde os maiores índices foram observados frente eritromicina e gentamicina, com 33,34% de sensibilidade para ambos; quanto à resistência desenvolvida, foi possível observar 100% de resistência com relação a vancomicina e tetraciclina, seguindo-se cloranfenicol, penicilina, ampicilina, cefoxitina, cefalotina, cefotaxima, norfloxacina e nitrofurantoína, todas evidenciando uma resistência de 83,33% das amostras testadas.The susceptibility of antimicrobials was studied in Gram positive and catalase negative cocci (21 samples of Lactococcus garvieae and 6 Enterococcus gallinarum, isolated from the milk of cows with subclinical mastitis, belonging to six buffalo herds in

  8. Antimicrobial effects of Thai medicinal plants against acne-inducing bacteria.

    Science.gov (United States)

    Chomnawang, Mullika Traidej; Surassmo, Suvimol; Nukoolkarn, Veena S; Gritsanapan, Wandee

    2005-10-03

    Propionibacterium acnes and Staphylococcus epidermidis have been recognized as pus-forming bacteria triggering an inflammation in acne. The present study was conducted to evaluate antimicrobial activities of Thai medicinal plants against these etiologic agents of acne vulgaris. Crude extracts were tested for antimicrobial activities by disc diffusion and broth dilution methods. The results from the disc diffusion method showed that 13 medicinal plants could inhibit the growth of Propionibacterium acnes. Among those, Senna alata, Eupatorium odoratum, Garcinia mangostana, and Barleria lupulina had strong inhibitory effects. Based on a broth dilution method, the Garcinia mangostana extract had the greatest antimicrobial effect. The MIC values were the same (0.039 mg/ml) for both bacterial species and the MBC values were 0.039 and 0.156 mg/ml against Propionibacterium acnes and Staphylococcus epidermidis, respectively. In bioautography assay, the Garcinia mangostana extract produced strong inhibition zones against Propionibacterium acnes. Antimicrobial activity from fractions of column chromatography revealed one of the active compounds in Garcinia mangostana could be mangostin, a xanthone derivative. Taken together, our data indicated that Garcinia mangostana had a strong inhibitory effect on Propionibacterium acnes and Staphylococcus epidermidis. Therefore, this plant would be an interesting topic for further study and possibly for an alternative treatment for acne.

  9. Carbon steel corrosion induced by sulphate-reducing bacteria in artificial seawater: electrochemical and morphological characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Paula, Mariana Silva de; Goncalves, Marcia Monteiro Machado; Rola, Monick Alves da Cruz; Maciel, Diana Jose; Senna, Lilian Ferreira de; Lago, Dalva Cristina Baptista do, E-mail: sdp.mari@gmail.com, E-mail: marciamg@uerj.br, E-mail: monickcruz@yahoo.com.br, E-mail: dijmaciel@gmail.com, E-mail: lsenna@uerj.br, E-mail: dalva@uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Instituto de Quimica

    2016-10-15

    In this work, the corrosion behavior of carbon steel AISI 1020 was evaluated in artificial seawater in the presence of mixed sulfate-reducing bacteria (SRB) culture isolated from the rust of a pipeline. The corrosion evaluation was performed by electrochemical techniques (open circuit potential (E{sub ocp}), polarization curves and electrochemical impedance spectroscopy (EIS)), while the formation of a biofilm and corrosion products were observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The presence of SRB in the medium shifted the open circuit potential to more positive values and increased the corrosion rate of the steel. Electrochemical and morphological techniques confirmed the presence of a biofilm on the steel surface. EDS spectra data showed the presence of sulfur in the corrosion products. After removing the biofilm, localized corrosion was observed on the surface, confirming that localized corrosion had occurred. The biogenic sulfide may lead to the formation of galvanic cells and contributes to cathodic depolarization. (author)

  10. Carbon steel corrosion induced by sulphate-reducing bacteria in artificial seawater: electrochemical and morphological characterizations

    International Nuclear Information System (INIS)

    Paula, Mariana Silva de; Goncalves, Marcia Monteiro Machado; Rola, Monick Alves da Cruz; Maciel, Diana Jose; Senna, Lilian Ferreira de; Lago, Dalva Cristina Baptista do

    2016-01-01

    In this work, the corrosion behavior of carbon steel AISI 1020 was evaluated in artificial seawater in the presence of mixed sulfate-reducing bacteria (SRB) culture isolated from the rust of a pipeline. The corrosion evaluation was performed by electrochemical techniques (open circuit potential (E_o_c_p), polarization curves and electrochemical impedance spectroscopy (EIS)), while the formation of a biofilm and corrosion products were observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The presence of SRB in the medium shifted the open circuit potential to more positive values and increased the corrosion rate of the steel. Electrochemical and morphological techniques confirmed the presence of a biofilm on the steel surface. EDS spectra data showed the presence of sulfur in the corrosion products. After removing the biofilm, localized corrosion was observed on the surface, confirming that localized corrosion had occurred. The biogenic sulfide may lead to the formation of galvanic cells and contributes to cathodic depolarization. (author)

  11. Antibiotic-resistant bacteria in drinking water.

    Science.gov (United States)

    Armstrong, J L; Shigeno, D S; Calomiris, J J; Seidler, R J

    1981-08-01

    We analyzed drinking water from seven communities for multiply antibiotic-resistant (MAR) bacteria (bacteria resistant to two or more antibiotics) and screened the MAR bacterial isolates obtained against five antibiotics by replica plating. Overall, 33.9% of 2,653 standard plate count bacteria from treated drinking waters were MAR. Two different raw water supplies for two communities carried MAR standard plate count bacteria at frequencies of 20.4 and 18.6%, whereas 36.7 and 67.8% of the standard plate count populations from sites within the respective distribution systems were MAR. Isolate identification revealed that MAR gram-positive cocci (Staphylococcus) and MAR gram-negative, nonfermentative rods (Pseudomonas, Alcaligenes, Moraxella-like group M, and Acinetobacter) were more common in drinking waters than in untreated source waters. Site-to-site variations in generic types and differences in the incidences of MAR organisms indicated that shedding of MAR bacteria living in pipelines may have contributed to the MAR populations in tap water. We conclude that the treatment of raw water and its subsequent distribution select for standard plate count bacteria exhibiting the MAR phenotype.

  12. Screening and biological characteristics of fufenozide degrading bacteria

    Science.gov (United States)

    Xu, Chenhao; Gong, Mingfu; Guan, Qinlan; Deng, Xia; Deng, Hongyan; Huang, Jiao

    2018-04-01

    Fufenozide was a novel pesticide for the control of Lepidoptera pests, which was highly toxic to silkworm. Fufenozide-contaminated soil samples were collected and the bacteria that degrade fufenozide were isolated and screened by selective medium. The colony characteristics, cell characteristics and degradation characteristics in different concentrations fufenozide of the fufenozide degrading bacteria were studied. The results indicated that seven strains of fufenozide degradeing bacteria, named as DDH01, DDH03, DDH04, DDH04, DDH05, DDH07 and DDH07 respectively, were isolated from soil contaminated with fufenozide. DDH01, DDH02, DDH04 and DDH05 of seven fufenozide degrading bacteria, was gram-positive bacteria, and DDH03, DDH06 and DDH07 was gram-negative bacteria. All of seven strains of fufenozide degrading bacteria were not spores, weeks flagella, rod-shaped bacteria. DDH06 and DDH07 had capsules, and the remaining five strains had not capsule. The colonies formed by seven strains of fufenozide degradation bacteria on beef extract peptone medium plate were milky white colonies with irregular edges, thinner lawn, smaller colony with smooth surface. The growth of 7 strains of fufenozide degradation bacteria was significantly affected by the concentration of fufenozide, All of 7 strains grown in the range from 0.00025 g/mL to 1 g/mL of 10% fufenozide suspension. DDH2 was the best among the 7 strains of fufenozide degrading bacteria grown in 10% fufenozide suspension medium.

  13. Streptococcus gordonii induces nitric oxide production through its lipoproteins stimulating Toll-like receptor 2 in murine macrophages.

    Science.gov (United States)

    Kim, Hyun Young; Baik, Jung Eun; Ahn, Ki Bum; Seo, Ho Seong; Yun, Cheol-Heui; Han, Seung Hyun

    2017-02-01

    Streptococcus gordonii, a Gram-positive commensal in the oral cavity, is an opportunistic pathogen that can cause endodontic and systemic infections resulting in infective endocarditis. Lipoteichoic acid (LTA) and lipoprotein are major virulence factors of Gram-positive bacteria that are preferentially recognized by Toll-like receptor 2 (TLR2) on immune cells. In the present study, we investigated the effect of S. gordonii LTA and lipoprotein on the production of the representative inflammatory mediator nitric oxide (NO) by the mouse macrophages. Heat-killed S. gordonii wild-type and an LTA-deficient mutant (ΔltaS) but not a lipoprotein-deficient mutant (Δlgt) induced NO production in mouse primary macrophages and the cell line, RAW 264.7. S. gordonii wild-type and ΔltaS also induced the expression of inducible NO synthase (iNOS) at the mRNA and protein levels. In contrast, the Δlgt mutant showed little effect under the same condition. Furthermore, S. gordonii wild-type and ΔltaS induced NF-κB activation, STAT1 phosphorylation, and IFN-β expression, which are important for the induction of iNOS gene expression, with little activation by Δlgt. S. gordonii wild-type and ΔltaS showed an increased adherence and internalization to RAW 264.7 cells compared to Δlgt. In addition, S. gordonii wild-type and ΔltaS, but not Δlgt, substantially increased TLR2 activation while none of these induced NO production in TLR2-deficient macrophages. Triton X-114-extracted lipoproteins from S. gordonii were sufficient to induce NO production. Collectively, we suggest that lipoprotein is an essential cell wall component of S. gordonii to induce NO production in macrophages through TLR2 triggering NF-κB and STAT1 activation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Commensal oral bacteria antigens prime human dendritic cells to induce Th1, Th2 or Treg differentiation.

    Science.gov (United States)

    Kopitar, A N; Ihan Hren, N; Ihan, A

    2006-02-01

    In various immunopathologic conditions, bacterial flora induce an immune response which results in inflammatory manifestations, e.g. periapical granuloma. Dendritic cells provide the main orchestration of specific immune responses. The aim of our study was to test the capacity of distinct oral bacterial antigens (prepared from Streptococcus mitis, Propionibacterium acnes, and Bacteroides spp.) to prime human dendritic cells for stimulation of the T-lymphocyte response. To assess the T-lymphocyte response, the expression of CD25, CD69, intracellular interferon gamma (cIFN-gamma), and intracellular interleukin 4 (cIL-4) was determined. Dendritic cells were prepared from leukocyte buffy coat from healthy blood donors. Monocytes were stimulated with IL-4 and GM-CSF and dendritic cells activated with bacterial lysates. Cell suspensions contained up to 90% dendritic cells, which represented 2-12% of the initial number of mononuclear cells. Lymphocyte subsets that developed in lymphocyte cultures after 1 week of stimulation were analyzed by flow cytometry. Dendritic cells, primed with antigens of Bacteroides fragilis have shown significantly higher activation and expression of intercellular IFN-gamma by T lymphocytes compared to negative controls. The dendritic cells primed with antigens of P. acnes had no effect on T-lymphocyte activation or cytokine production; instead they induced differentiation of T lymphocytes into CD25bright cells (regulatory T cells) with a potentially inhibitory effect on immune response. Dendritic cells primed with antigens of S. mitis induced increased expression of cIL-4. We conclude that commensal oral bacteria antigens prepared from B. fragilis, S. mitis, and P. acnes prime human dendritic cells to induce Th1, Th2, and T(reg) differentiation, respectively. This may advance our understanding of immunopathologic manifestations in the oral cavity and offer new possibilities for redirecting immune responses in mucosal vaccination.

  15. Bactericidal peptidoglycan recognition protein induces oxidative stress in Escherichia coli through a block in respiratory chain and increase in central carbon catabolism.

    Science.gov (United States)

    Kashyap, Des R; Kuzma, Marcin; Kowalczyk, Dominik A; Gupta, Dipika; Dziarski, Roman

    2017-09-01

    Mammalian Peptidoglycan Recognition Proteins (PGRPs) kill both Gram-positive and Gram-negative bacteria through simultaneous induction of oxidative, thiol and metal stress responses in bacteria. However, metabolic pathways through which PGRPs induce these bactericidal stress responses are unknown. We screened Keio collection of Escherichia coli deletion mutants and revealed that deleting genes for respiratory chain flavoproteins or for tricarboxylic acid (TCA) cycle resulted in increased resistance of E. coli to PGRP killing. PGRP-induced killing depended on the production of hydrogen peroxide, which required increased supply of NADH for respiratory chain oxidoreductases from central carbon catabolism (glycolysis and TCA cycle), and was controlled by cAMP-Crp. Bactericidal PGRP induced a rapid decrease in respiration, which suggested that the main source of increased production of hydrogen peroxide was a block in respiratory chain and diversion of electrons from NADH oxidoreductases to oxygen. CpxRA two-component system was a negative regulator of PGRP-induced oxidative stress. By contrast, PGRP-induced thiol stress (depletion of thiols) and metal stress (increase in intracellular free Zn 2+ through influx of extracellular Zn 2+ ) were mostly independent of oxidative stress. Thus, manipulating pathways that induce oxidative, thiol and metal stress in bacteria could be a useful strategy to design new approaches to antibacterial therapy. © 2017 John Wiley & Sons Ltd.

  16. [GEIPC-SEIMC (Study Group for Infections in the Critically Ill Patient of the Spanish Society for Infectious Diseases and Clinical Microbiology) and GTEI-SEMICYUC ( Working Group on Infectious Diseases of the Spanish Society of Intensive Medicine, Critical Care, and Coronary Units) recommendations for antibiotic treatment of gram-positive cocci infections in the critical patient].

    Science.gov (United States)

    Astigarraga, P M Olaechea; Montero, J Garnacho; Cerrato, S Grau; Colomo, O Rodríguez; Martínez, M Palomar; Crespo, R Zaragoza; García-Paredes, P Muñoz; Cerdá, E Cerdá; Lerma, F Alvarez

    2007-01-01

    In recent years, an increment of infections caused by gram-positive cocci has been documented in nosocomial and hospital-acquired-infections. In diverse countries, a rapid development of resistance to common antibiotics against gram-positive cocci has been observed. This situation is exceptional in Spain but our country might be affected in the near future. New antimicrobials active against these multi-drug resistant pathogens are nowadays available. It is essential to improve our current knowledge about pharmacokinetic properties of traditional and new antimicrobials to maximize its effectiveness and to minimize toxicity. These issues are even more important in critically ill patients because inadequate empirical therapy is associated with therapeutic failure and a poor outcome. Experts representing two scientific societies (Grupo de estudio de Infecciones en el Paciente Crítico de la SEIMC and Grupo de trabajo de Enfermedades Infecciosas de la SEMICYUC) have elaborated a consensus document based on the current scientific evidence to summarize recommendations for the treatment of serious infections caused by gram-positive cocci in critically ill patients.

  17. [Distribution and drug resistance of the pathogenic bacteria from sputum specimens of 1 125 children with tracheo bronchial foreign bodies].

    Science.gov (United States)

    Wen, Xin; Su, Jinzhu; Cui, Li; Wang, Juan; Zuo, Lujie

    2015-02-01

    To analyze the distribution and drug susceptibility of the pathogenic bacteria in the airway secretions in children with tracheobronchial foreign bodies so as to assist physicians in clinical prescription. Sputum specimens of 1 125 children with tracheobronchial foreign bodies were collected in removal of the foreign bodies by rigid bronchoscope, and the drug susceptibility test was performed. Pathogenic bacteria were detected in 218 (19.4%) of 1 125 sputum specimens. Among the pathogenic bacteria, 126 (57.79%) strains were gram-negative bacilli, consisting of 76 (34.86%) strains of Haemophilus influenzae, 10 (4.59%) strains of Escherichia coli, 7 (3.21%) strains of Sewer enterobacter, 7 (3.21%) strains of Pseudomonas aeruginosa, and 6 (2.75%) strains of Klebsiella bacillus; and 92 (42.21%) strains were gram-positive bacilli, consisting of 80 (36.69%) strains of Streptococcus pneumonia and 10 (4.59%) strains of Escherichia coli. Most of detected gram-negative bacilli were highly sensitive to cefepime, ceftazidine, imipenem and amikacin, no strains were resistant to meropenem and ciprofloxacin. None of the detected gram-positive bacilli were resistant to cefepime, vancomycin, levofloxacin and teicoplanin. The Haemophilus influenzae of gram-negative bacilli and the Streptococcus pneumonia of gram-positive bacilli are the main pathogenic bacteria existing in the airway secretions of children with tracheobronchial foreign bodies. The Haemophilus influenzae were highly sensitive to cephalosporin, imipenem and amikacin, and the Streptococcus pneumonia to cefepime, vancomycin, levofloxacin and teicoplanin.

  18. Clostridium difficile toxin CDT induces formation of microtubule-based protrusions and increases adherence of bacteria.

    Directory of Open Access Journals (Sweden)

    Carsten Schwan

    2009-10-01

    Full Text Available Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis by production of the Rho GTPase-glucosylating toxins A and B. Recently emerging hypervirulent Clostridium difficile strains additionally produce the binary ADP-ribosyltransferase toxin CDT (Clostridium difficile transferase, which ADP-ribosylates actin and inhibits actin polymerization. Thus far, the role of CDT as a virulence factor is not understood. Here we report by using time-lapse- and immunofluorescence microscopy that CDT and other binary actin-ADP-ribosylating toxins, including Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin, induce redistribution of microtubules and formation of long (up to >150 microm microtubule-based protrusions at the surface of intestinal epithelial cells. The toxins increase the length of decoration of microtubule plus-ends by EB1/3, CLIP-170 and CLIP-115 proteins and cause redistribution of the capture proteins CLASP2 and ACF7 from microtubules at the cell cortex into the cell interior. The CDT-induced microtubule protrusions form a dense meshwork at the cell surface, which wrap and embed bacterial cells, thereby largely increasing the adherence of Clostridia. The study describes a novel type of microtubule structure caused by less efficient microtubule capture and offers a new perspective for the pathogenetic role of CDT and other binary actin-ADP-ribosylating toxins in host-pathogen interactions.

  19. Dynamic chemical communication between plants and bacteria through airborne signals: induced resistance by bacterial volatiles.

    Science.gov (United States)

    Farag, Mohamed A; Zhang, Huiming; Ryu, Choong-Min

    2013-07-01

    Certain plant growth-promoting rhizobacteria (PGPR) elicit induced systemic resistance (ISR) and plant growth promotion in the absence of physical contact with plants via volatile organic compound (VOC) emissions. In this article, we review the recent progess made by research into the interactions between PGPR VOCs and plants, focusing on VOC emission by PGPR strains in plants. Particular attention is given to the mechanisms by which these bacterial VOCs elicit ISR. We provide an overview of recent progress in the elucidation of PGPR VOC interactions from studies utilizing transcriptome, metabolome, and proteome analyses. By monitoring defense gene expression patterns, performing 2-dimensional electrophoresis, and studying defense signaling null mutants, salicylic acid and ethylene have been found to be key players in plant signaling pathways involved in the ISR response. Bacterial VOCs also confer induced systemic tolerance to abiotic stresses, such as drought and heavy metals. A review of current analytical approaches for PGPR volatile profiling is also provided with needed future developments emphasized. To assess potential utilization of PGPR VOCs for crop plants, volatile suspensions have been applied to pepper and cucumber roots and found to be effective at protecting plants against plant pathogens and insect pests in the field. Taken together, these studies provide further insight into the biological and ecological potential of PGPR VOCs for enhancing plant self-immunity and/or adaptation to biotic and abiotic stresses in modern agriculture.

  20. Multi-scale model of drug induced adaptive resistance of Gram-negative bacteria to polymyxin B.

    Directory of Open Access Journals (Sweden)

    Wojciech Krzyzanski

    Full Text Available The purpose of this report is to apply multi-scale modeling using the theory of physiologically structured populations (PSP to develop a mathematical model for antimicrobial resistance based on a heterogeneous distribution of receptors and affinities among bacterial cells. The theory has been tested on data obtained from an in vitro static time-kill infection model analyzing the pharmacodynamics of polymyxin B against Gram-negative bacteria. The drug binding parameter KD (dissociation equilibrium constant is assumed to vary between the bacterial cells. The PSP model describes the time course of the density distribution of KD upon exposure to cytotoxic drug concentrations. The drug increases the hazard of cell death as a function of receptor occupancy. The initial distribution of KD is described by the Weibull function. Time-kill data were used for model qualification. In vitro static time-kill experiments to evaluate the rate and extent of killing due to polymyxin B against two Klebsiella pneumoniae clinical isolates with differing susceptibilities to polymyxin B were performed over 48 h. The time-kill kinetics data of bacterial load cfu (colony forming units/mL was used for model qualification. The resistant bacterial population is determined by the balance between growth rate and hazard of cell death controlled by polymyxin B concentrations. There exists a critical KD value below which cells continue to grow. Estimates of shape parameters for distributions of KD yielded unimodal distributions with the modes at 0 nM and the right tails containing approximately 25% of the bacteria. Our findings support a hypothesis that resistance of Klebsiella pneumoniae to polymyxin B can be at least partially attributed to a drug-induced selection of a subpopulation due to heterogeneity of polymyxin B receptor binding in the bacterial population.

  1. Development of an equipment for the detection and measurement of localized corrosion of carbon steel induced by sulfidogenic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cotiche, C. [CFG Services, 3 avenue Claude Guillemin, BP 6429, 45064 Orleans Cedex (France); Dauma, S. [CFG Services, 117 avenue de Luminy, 13009 Marseille (France)

    2004-07-01

    Most of the geothermal installations exploiting the Dogger aquifer of the Paris basin are faced to corrosion and scaling problems. Localized corrosion phenomena due to the presence of sulfate reducing bacteria which have been identified in the geothermal water and in scales deposited on corrosion coupons is the most insidious being able to induce rapid failures of the casings of production and injection wells and surface pipelines. In order to evaluate and prevent the occurrence of such corrosion risks that are similar to those encountered in oil and gas industry, a specific equipment has been developed by CFG Services, engineering company specialized in the exploitation and maintenance of geothermal plants. This equipment which includes a probe and an electronic device has to be installed on the pipeline transporting the corrosive medium through a nipple secured to it. The principle is based on the generation of a pit on a circular electrode in carbon steel by anodic polarization and on the measurement of the corrosion current between this electrode and the pipeline or the probe body used as cathodic pole. Then, the current freely flowing between the anode and cathode is monitored and used to estimate if the pitting corrosion artificially created by an electric pulse may be maintained or not by the activity of sulfidogenic bacteria which may have developed on the surface of the electrode. This equipment has been tested on a geothermal exploitation where the risk of microbial corrosion has been identified and the sensibility of the signal of the probe to the injection of biocide products proved. (authors)

  2. Study on Protease Enzyme Produced by Pathogenic Bacteria

    International Nuclear Information System (INIS)

    Abd Elhakim, E.E.

    2014-01-01

    A total of 110 surface swabs were taken from skin of burned and post burn wounded patients. Infected swabs from burned patients were found to be 62.8% and 63.6%,while post burn wounded patients were 66.7% and 69.2% in male and female patients, respectively. The burned and post burn wounded patients were infected with bacteria in the order of gram negative bacilli >gram positive cocci>gram positive bacilli .Pseudomonas aeruginosa,Proteus mirabilis,Bacillus megaterium and Bacillus cereus showed the highest proteolytic activity. The effect of cultivation condition,different media, incubation time, incubation temperature, ph, metal ions, inhibitors and different doses of gamma radiation on the proteolytic activity of the tested bacterial isolates showing the highest proteolytic activity were studied. The tested bacterial isolates showed susceptibility to some antibiotics and showed resistance to the others. The effects of gamma radiation on the tested bacteria and on the susceptibility of the tested bacteria isolates to antibiotics under test were studied.

  3. Studying antimicrobial-induced morphostructural damage of bacteria by Scanning Electron Microscope

    Directory of Open Access Journals (Sweden)

    Shruti Shukla

    2015-12-01

    Full Text Available In this investigation, a scanning electron microscopy (SEM method was used to examine the morphostructural changes in bacterial cells induced by antimicrobial agents. SEM-based visual approach is referred the study of bacterial cells and their physiological consequences when affected by antibiotics or antibacterial agents permitting the observation of characteristic morphological defects of cell wall, and provides valuable insights into processes involved in bacterial cell death. This experiment visualized various step-by-step techniques used in the slide preparation of bacterial cells treated with specific antimicrobial agent for analyzing the morphological alterations such as increase of cell wall roughness, cell disruption, cell swelling and lysed cell formation due to loss of intracellular material using SEM analysis when compared with untreated normal cells as a control. The SEM approach used in this visual experiment may analyze the antimicrobial effect of any commercially known or new compounds in a very conducive manner.

  4. Nutrient enrichment induces dormancy and decreases diversity of active bacteria in salt marsh sediments

    Science.gov (United States)

    Kearns, Patrick J.; Angell, John H.; Howard, Evan M.; Deegan, Linda A.; Stanley, Rachel H. R.; Bowen, Jennifer L.

    2016-09-01

    Microorganisms control key biogeochemical pathways, thus changes in microbial diversity, community structure and activity can affect ecosystem response to environmental drivers. Understanding factors that control the proportion of active microbes in the environment and how they vary when perturbed is critical to anticipating ecosystem response to global change. Increasing supplies of anthropogenic nitrogen to ecosystems globally makes it imperative that we understand how nutrient supply alters active microbial communities. Here we show that nitrogen additions to salt marshes cause a shift in the active microbial community despite no change in the total community. The active community shift causes the proportion of dormant microbial taxa to double, from 45 to 90%, and induces diversity loss in the active portion of the community. Our results suggest that perturbations to salt marshes can drastically alter active microbial communities, however these communities may remain resilient by protecting total diversity through increased dormancy.

  5. [Daptomycin: revitalizing a former drug due to the need of new active agents against grampositive multiresistant bacterias].

    Science.gov (United States)

    Hernández Martí, V; Romá Sánchez, E; Salavert Lletí, M; Bosó Ribelles, V; Poveda Andrés, J L

    2007-09-01

    The development of mechanisms of resistance of many Gram-positive bacterial strains that cause complicated skin and soft tissue infections, as well as sepsis and bacteremia, has necessitated the search for new drugs that will improve treatment strategies. Daptomycin is a cyclic lipopeptide antibacterial that was launched for the treatment of complicated skin and soft tissue infections caused by Gram-positive organisms. The drug's mechanism of action is different from that of any other antibiotic. It binds to bacterial membranes and causes a rapid depolarization of membrane potential. This loss of membrane potential causes inhibition of protein, DNA and RNA synthesis, which results in bacterial cell death. The in vitro spectrum of activity of daptomycin encompasses most clinically relevant aerobic Gram-positive pathogenic bacteria. Compared to other antibiotics with a similar antibacterial spectrum, daptomycin does not cause nephrotoxicity. Taking these and other characteristics into consideration, daptomycin appears to be a good alternative to other drugs used in the treatment of complicated skin and soft tissue infections and in Gram-positive bacteremial infections.

  6. Aggregation-Induced-Emission Materials with Different Electric Charges as an Artificial Tongue: Design, Construction, and Assembly with Various Pathogenic Bacteria for Effective Bacterial Imaging and Discrimination.

    Science.gov (United States)

    Liu, Guang-Jian; Tian, Sheng-Nan; Li, Cui-Yun; Xing, Guo-Wen; Zhou, Lei

    2017-08-30

    Imaging-based total bacterial count and type identification of bacteria play crucial roles in clinical diagnostics, public health, biological and medical science, and environmental protection. Herein, we designed and synthesized a series of tetraphenylethenes (TPEs) functionalized with one or two aldehyde, carboxylic acid, and quaternary ammonium groups, which were successfully used as fluorescent materials for rapid and efficient staining of eight kinds of representative bacterial species, including pathogenic bacteria Vibrio cholera, Klebsiella pneumoniae, and Listeria monocytogenes and potential bioterrorism agent Yersinia pestis. By comparing the fluorescence intensity changes of the aggregation-induced-emission (AIE) materials before and after bacteria incubation, the sensing mechanisms (electrostatic versus hydrophobic interactions) were simply discussed. Moreover, the designed AIE materials were successfully used as an efficient artificial tongue for bacteria discrimination, and all of the bacteria tested were identified via linear discriminant analysis. Our current work provided a general method for simultaneous broad-spectrum bacterial imaging and species discrimination, which is helpful for bacteria surveillance in many fields.

  7. Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chuang [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China); Yang Dong; Wang Yuangui [Tianjin University, Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology (China); Shi Jiafu; Jiang Zhongyi, E-mail: zhyjiang@tju.edu.cn [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China)

    2012-08-15

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total 'biologic' route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  8. Fabrication of antimicrobial bacterial cellulose–Ag/AgCl nanocomposite using bacteria as versatile biofactory

    International Nuclear Information System (INIS)

    Liu Chuang; Yang Dong; Wang Yuangui; Shi Jiafu; Jiang Zhongyi

    2012-01-01

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total “biologic” route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC–Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  9. Isolation and characterization of osmotolerant bacteria from Thar Desert of Western Rajasthan (India

    Directory of Open Access Journals (Sweden)

    Ramavtar Sharma

    2013-12-01

    Full Text Available The Thar Desert harsher environment harbors a limited diversity of life forms due to extreme conditions like low moisture of sandy soils and high soil temperature. In the present study, osmotolerant bacteria from the Thar soils were isolated and characterized. Bacteria were isolated from 20 soil samples (100g, collected from sand dunes, suspended in water and absolute alcohol. A total of 11 biochemical and morphological tests were carried out for generic identification of bacteria. Osmotic tolerance capacity of isolates was examined on glycerol, NaCl and alcohol; and sequencing of 16S rRNA gene was also performed for bacterial identification. 16S to 23S rRNA internal transcribed spacer analysis (RISA was done for phylogenetic analysis of isolates. The soil suspended in water contained 2.5×10(6 bacteria/g of soil while alcohol suspended soil had 4.4×10(4 bacteria/g. The 24 bacterial isolates were found tolerant to 26% glycerol, 14% NaCl and 10% of alcohol, and 22 out of 24 isolates were found Gram positive. The results showed that 45.83% and 41.67% bacteria belong to Bacillus spp. and Corynebacterium spp., respectively, while Acinetobacter spp., Aeromonas spp. and Staphylococcus spp. were in equal proportion (4.16% each. Six isolates were selected for 16S rRNA gene sequencing and five were found 95% similar with Bacillus licheniformis whereas one isolate was identified as B. subtilis. All the isolates showed good growth up to 50°C with gradual reduction on subsequent increment of temperature. Out of 24 isolates, six could survive at 65°C while one isolate could grow at 63°C. Growth kinetic studies revealed that the reduction in generation time in solute(s and temperature stress was more as compared to generation time in plain medium. This study suggests that virgin sand dunes may be a rich source of bacteria, tolerant to osmotrophic solutes, and can be examined for plant growth promotion activity in agriculture. Moreover, study might help to

  10. Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site

    International Nuclear Information System (INIS)

    Daly, Michael J.

    2006-01-01

    Ionizing Radiation (IR) Resistance in Bacteria. Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR) and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (e.g., Deinococcus, Arthrobacter, Lactobacillus and Enterococcus spp.) and the most sensitive have been Gram-negative (e.g., Pseudomonas, Shewanella and Neisseria spp.). However, there are several reported exceptions to this paradigm, the Gram-negative cyanobacterium Chroococcidiopsis is extremely resistant to IR, whereas the Gram-positive Micrococcus luteus is sensitive. We have identified biomolecular signatures for radiation sensitivity and resistance which are independent of phylogeny, where very high and very low intracellular Mn/Fe concentration ratios correlated with very high and very low resistances, respectively; and restricting Mn(II) in the famously resistant Deinococcus radiodurans sensitized this eubacterium to IR

  11. Characterizing the Catalytic Potential of Deinococcus, Arthrobacter and other Robust Bacteria in Contaminated Subsurface Environments of the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Daly, Michael J.

    2006-05-01

    Ionizing Radiation (IR) Resistance in Bacteria. Until recently, there have been no clear physiologic predictors of a cell's ability to recover from ionizing radiation (IR) and other DOE-relevant oxidative stress conditions. In general, the most resistant bacteria have been Gram-positive (e.g., Deinococcus, Arthrobacter, Lactobacillus & Enterococcus spp.) and the most sensitive have been Gram-negative (e.g., Pseudomonas, Shewanella & Neisseria spp.). However, there are several reported exceptions to this paradigm, the Gram-negative cyanobacterium Chroococcidiopsis is extremely resistant to IR, whereas the Gram-positive Micrococcus luteus is sensitive. We have identified biomolecular signatures for radiation sensitivity and resistance which are independent of phylogeny, where very high and very low intracellular Mn/Fe concentration ratios correlated with very high and very low resistances, respectively; and restricting Mn(II) in the famously resistant Deinococcus radiodurans sensitized this eubacterium to IR.

  12. Commensal bacteria and MAMPs are necessary for stress-induced increases in IL-1β and IL-18 but not IL-6, IL-10 or MCP-1.

    Directory of Open Access Journals (Sweden)

    Thomas Maslanik

    Full Text Available Regular interactions between commensal bacteria and the enteric mucosal immune environment are necessary for normal immunity. Alterations of the commensal bacterial communities or mucosal barrier can disrupt immune function. Chronic stress interferes with bacterial community structure (specifically, α-diversity and the integrity of the intestinal barrier. These interferences can contribute to chronic stress-induced increases in systemic IL-6 and TNF-α. Chronic stress, however, produces many physiological changes that could indirectly influence immune activity. In addition to IL-6 and TNF-α, exposure to acute stressors upregulates a plethora of inflammatory proteins, each having unique synthesis and release mechanisms. We therefore tested the hypothesis that acute stress-induced inflammatory protein responses are dependent on the commensal bacteria, and more specifically, lipopolysaccharide (LPS shed from Gram-negative intestinal commensal bacteria. We present evidence that both reducing commensal bacteria using antibiotics and neutralizing LPS using endotoxin inhibitor (EI attenuates increases in some (inflammasome dependent, IL-1 and IL-18, but not all (inflammasome independent, IL-6, IL-10, and MCP-1 inflammatory proteins in the blood of male F344 rats exposed to an acute tail shock stressor. Acute stress did not impact α- or β- diversity measured using 16S rRNA diversity analyses, but selectively reduced the relative abundance of Prevotella. These findings indicate that commensal bacteria contribute to acute stress-induced inflammatory protein responses, and support the presence of LPS-mediated signaling in stress-evoked cytokine and chemokine production. The selectivity of the commensal bacteria in stress-evoked IL-1β and IL-18 responses may implicate the inflammasome in this response.

  13. Microbially induced separation of quartz from hematite using sulfate reducing bacteria.

    Science.gov (United States)

    Prakasan, M R Sabari; Natarajan, K A

    2010-07-01

    Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment. The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation. 2010 Elsevier B.V. All rights reserved.

  14. Influence of superinfection on the photoreversible phase of UV induced lysogenic bacteria

    International Nuclear Information System (INIS)

    Theile, M.; Scherneck, S.; Geissler, E.

    1981-01-01

    1. Lysogenic induction by UV light can be reversed by photoreactivation. UV-treated E. coli K12 (lambda) + uvr + and uvr cells are sensitive to photoreactivation for a given time after irradiation. This sensitivity suddenly disappears at the end of this time. 2. The photoreversible period of UV induction is more than twice as long in uvr cells as it is in uvr + cells. 3. The photoreversible period can be reduced by superinfection with lambdac mutants after irradiation. This effect is positively correlated with the multiplicity of superinfection. Such a reduction does not occur when superinfection is carried out with wild-type phages or with heteroimmune derivatives. 4. We concluded that during the photoreversible period of UV induction oligonucleotides are excised or synthesized and gaps are formed during excision repair and post replication repair of UV damage; these might react with E. coli recA protein thereby activating it to induce its own synthesis, to cleave phage repressors and to exert its other SOS functions. (orig.)

  15. EFFECT OF SILICATE ON GRAM STAINING AND VIABILITY OF PNEUMOCOCCI AND OTHER BACTERIA

    Science.gov (United States)

    MacLeod, Colin M.; Roe, Amy S.

    1956-01-01

    Application of silicate solutions to living or heat-killed pneumococci and to certain "viridans" streptococci causes their conversion from a Gram-positive to a Gram-negative state. The original staining properties can be restored by suspending the silicate-treated bacteria in alkaline solutions of various salts but not by simple washing in water. Living pneumococci and the strains of streptococci whose staining properties are similarly affected are killed when suspended in silicate solutions. In other Gram-positive species silicate causes conversion to Gram negativity but restoration to positivity occurs upon washing in water. In a third group of Gram-positive organisms silicate has no effect on the Gram reaction. The viability of organisms in these two groups is unaffected by silicate under the conditions employed. No effect on staining or viability of Gram-negative bacteria has been observed. The effects of silicate on staining and viability are inhibited by nutrient broth or whole serum but not by purified serum albumin. Lecithin, choline, and other substituted ammonium compounds also inhibit the effects of silicate on pneumococci. PMID:13306854

  16. Combination of laser-induced breakdown spectroscopy and Raman spectroscopy for multivariate classification of bacteria

    Science.gov (United States)

    Prochazka, D.; Mazura, M.; Samek, O.; Rebrošová, K.; Pořízka, P.; Klus, J.; Prochazková, P.; Novotný, J.; Novotný, K.; Kaiser, J.

    2018-01-01

    In this work, we investigate the impact of data provided by complementary laser-based spectroscopic methods on multivariate classification accuracy. Discrimination and classification of five Staphylococcus bacterial strains and one strain of Escherichia coli is presented. The technique that we used for measurements is a combination of Raman spectroscopy and Laser-Induced Breakdown Spectroscopy (LIBS). Obtained spectroscopic data were then processed using Multivariate Data Analysis algorithms. Principal Components Analysis (PCA) was selected as the most suitable technique for visualization of bacterial strains data. To classify the bacterial strains, we used Neural Networks, namely a supervised version of Kohonen's self-organizing maps (SOM). We were processing results in three different ways - separately from LIBS measurements, from Raman measurements, and we also merged data from both mentioned methods. The three types of results were then compared. By applying the PCA to Raman spectroscopy data, we observed that two bacterial strains were fully distinguished from the rest of the data set. In the case of LIBS data, three bacterial strains were fully discriminated. Using a combination of data from both methods, we achieved the complete discrimination of all bacterial strains. All the data were classified with a high success rate using SOM algorithm. The most accurate classification was obtained using a combination of data from both techniques. The classification accuracy varied, depending on specific samples and techniques. As for LIBS, the classification accuracy ranged from 45% to 100%, as for Raman Spectroscopy from 50% to 100% and in case of merged data, all samples were classified correctly. Based on the results of the experiments presented in this work, we can assume that the combination of Raman spectroscopy and LIBS significantly enhances discrimination and classification accuracy of bacterial species and strains. The reason is the complementarity in

  17. Phylogenetic Diversity of Lactic Acid Bacteria Associated with Paddy Rice Silage as Determined by 16S Ribosomal DNA Analysis

    OpenAIRE

    Ennahar, Saïd; Cai, Yimin; Fujita, Yasuhito

    2003-01-01

    A total of 161 low-G+C-content gram-positive bacteria isolated from whole-crop paddy rice silage were classified and subjected to phenotypic and genetic analyses. Based on morphological and biochemical characters, these presumptive lactic acid bacterium (LAB) isolates were divided into 10 groups that included members of the genera Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Weissella. Analysis of the 16S ribosomal DNA (rDNA) was used to confirm the presence of the ...

  18. Isolation and Identification of the Chitinolytic Bacteria from Rumen Ecosystem

    Directory of Open Access Journals (Sweden)

    Sri Rahayu

    2003-05-01

    Full Text Available Rumen is an interesting ecosystem for microbial exploration and their products. Isolation of the chitinolytic bacteria from the rumen ecosystem found 109 colonies that produced clear zone, 84 colonies (86% anaerobic and 17 colonies (14% aerobic. Clear zone appeared in the third and fourth days incubation. Four potential isolates were chosen for identification purposes. Results showed that the bacteria were sticky, gram-positive, motile, endospore-forming, mesophilic and aerobic. It was supposed to Bacillus spp. the optimal pH and temperature to produce chitinase from isolate 18 are pH 6.0 and temperature of 35-40ºC. Divalent cations Mg, Ca, Zn, and Mn increase chitinase activity, while Cu and Co inhibit enzyme activity. When isolate 18 was grown on shrimp waste meal, it showed aptimal activity on the fifth days incubation. (Animal Production 5(2: 73-78 (2003   Key Words : Isolation, Identification, Chitinolytic Bacteria, Rumen

  19. Effect of carbon sources on the aggregation of photo fermentative bacteria induced by L-cysteine for enhancing hydrogen production.

    Science.gov (United States)

    Xie, Guo-Jun; Liu, Bing-Feng; Ding, Jie; Wang, Qilin; Ma, Chao; Zhou, Xu; Ren, Nan-Qi

    2016-12-01

    Poor flocculation of photo fermentative bacteria resulting in continuous biomass washout from photobioreactor is a critical challenge to achieve rapid and stable hydrogen production. In this work, the aggregation of Rhodopseudomonas faecalis RLD-53 was successfully developed in a photobioreactor and the effects of different carbon sources on hydrogen production and aggregation ability were investigated. Extracellular polymeric substances (EPS) production by R. faecalis RLD-53 cultivated using different carbon sources were stimulated by addition of L-cysteine. The absolute ζ potentials of R. faecalis RLD-53 were considerably decreased with addition of L-cysteine, and aggregation barriers based on DLVO dropped to 15-43 % of that in control groups. Thus, R. faecalis RLD-53 flocculated effectively, and aggregation abilities of strain RLD-53 cultivated with acetate, propionate, lactate and malate reached 29.35, 32.34, 26.07 and 24.86 %, respectively. In the continuous test, hydrogen-producing activity was also promoted and reached 2.45 mol H 2 /mol lactate, 3.87 mol H 2 /mol propionate and 5.10 mol H 2 /mol malate, respectively. Therefore, the aggregation of R. faecalis RLD-53 induced by L-cysteine is independent on the substrate types, which ensures the wide application of this technology to enhance hydrogen recovery from wastewater dominated by different organic substrates.

  20. Use of superoxide dismutase and catalase producing lactic acid bacteria in TNBS induced Crohn's disease in mice.

    Science.gov (United States)

    LeBlanc, Jean Guy; del Carmen, Silvina; Miyoshi, Anderson; Azevedo, Vasco; Sesma, Fernando; Langella, Philippe; Bermúdez-Humarán, Luis G; Watterlot, Laurie; Perdigon, Gabriela; de Moreno de LeBlanc, Alejandra

    2011-02-10

    Reactive oxygen species are involved in various aspects of intestinal inflammation and tumor development. Decreasing their levels using antioxidant enzymes, such as catalase (CAT) or superoxide dismutase (SOD) could therefore be useful in the prevention of certain diseases. Lactic acid bacteria (LAB) are ideal candidates to deliver these enzymes in the gut. In this study, the anti-inflammatory effects of CAT or SOD producing LAB were evaluated using a trinitrobenzenesulfonic acid (TNBS) induced Crohn's disease murine model. Engineered Lactobacillus casei BL23 strains producing either CAT or SOD, or the native strain were given to mice before and after intrarectal administration of TNBS. Animal survival, live weight, intestinal morphology and histology, enzymatic activities, microbial translocation to the liver and cytokines released in the intestinal fluid were evaluated. The mice that received CAT or SOD-producing LAB showed a faster recovery of initial weight loss, increased enzymatic activities in the gut and lesser extent of intestinal inflammation compared to animals that received the wild-type strain or those that did not receive bacterial supplementation. Our findings suggest that genetically engineered LAB that produce antioxidant enzymes could be used to prevent or decrease the severity of certain intestinal pathologies. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Aerobic salivary bacteria in wild and captive Komodo dragons.

    Science.gov (United States)

    Montgomery, Joel M; Gillespie, Don; Sastrawan, Putra; Fredeking, Terry M; Stewart, George L

    2002-07-01

    During the months of November 1996, August 1997, and March 1998, saliva and plasma samples were collected for isolation of aerobic bacteria from 26 wild and 13 captive Komodo dragons (Varanus komodoensis). Twenty-eight Gram-negative and 29 Gram-positive species of bacteria were isolated from the saliva of the 39 Komodo dragons. A greater number of wild than captive dragons were positive for both Gram-negative and Gram-positive bacteria. The average number of bacterial species within the saliva of wild dragons was 46% greater than for captive dragons. While Escherichia coli was the most common bacterium isolated from the saliva of wild dragons, this species was not present in captive dragons. The most common bacteria isolated from the saliva of captive dragons were Staphylococcus capitis and Staphylococcus capitis and Staphylococcus caseolyticus, neither of which were found in wild dragons. High mortality was seen among mice injected with saliva from wild dragons and the only bacterium isolated from the blood of dying mice was Pasteurella multocida. A competitive inhibition enzyme-linked immunosorbent assay revealed the presence of anti-Pasteurella antibody in the plasma of Komodo dragons. Four species of bacteria isolated from dragon saliva showed resistance to one or more of 16 antimicrobics tested. The wide variety of bacteria demonstrated in the saliva of the Komodo dragon in this study, at least one species of which was highly lethal in mice and 54 species of which are known pathogens, support the observation that wounds inflicted by this animal are often associated with sepsis and subsequent bacteremia in prey animals.

  2. Enhanced performance of the microalga Chlorella sorokiniana remotely induced by the plant growth-promoting bacteria Azospirillum brasilense and Bacillus pumilus

    Science.gov (United States)

    Amavizca, Edgar; Bashan, Yoav; Ryu, Choong-Min; Farag, Mohamed A.; Bebout, Brad M.; de-Bashan, Luz E.

    2017-01-01

    Remote effects (occurring without physical contact) of two plant growth-promoting bacteria (PGPB) Azospirillum brasilense Cd and Bacilus pumilus ES4 on growth of the green microalga Chlorella sorokiniana UTEX 2714 were studied. The two PGPB remotely enhanced the growth of the microalga, up to six-fold, and its cell volume by about three-fold. In addition to phenotypic changes, both bacteria remotely induced increases in the amounts of total lipids, total carbohydrates, and chlorophyll a in the cells of the microalga, indicating an alteration of the microalga’s physiology. The two bacteria produced large amounts of volatile compounds, including CO2, and the known plant growth-promoting volatile 2,3-butanediol and acetoin. Several other volatiles having biological functions in other organisms, as well as numerous volatile compounds with undefined biological roles, were detected. Together, these bacteria-derived volatiles can positively affect growth and metabolic parameters in green microalgae without physical attachment of the bacteria to the microalgae. This is a new paradigm on how PGPB promote growth of microalgae which may serve to improve performance of Chlorella spp. for biotechnological applications. PMID:28145473

  3. Anti-nociceptive properties in rodents and the possibility of using polyphenol-rich fractions from sida urens L. (Malvaceae) against of dental caries bacteria.

    Science.gov (United States)

    Konaté, Kiessoun; Zerbo, Patrice; Ouédraogo, Maurice; Dibala, Crépin I; Adama, Hilou; Sytar, Oksana; Brestic, Marian; Barro, Nicolas

    2013-06-21

    Sida urens L. (Malvaceae) is in flora of Asian medicinal herbs and used traditionally in West of Burkina Faso for the treatment of infectious diseases and particularly used against, dental caries bacteria, fever, pain and possesses analgesic properties. This study was conducted to reveal the antibacterial effect against dental caries bacteria on the one hand, and evaluate their analgesic capacity in experimental model with Swiss mice and on the other hand, with an aim to provide a scientific basis for the traditional use of this plant for the management of dental caries bacteria. The antibacterial assays in this study were performed by using inhibition zone diameters, MIC (Minimum inhibitory concentration) and MBC (Minimal bactericidal concentration) methods. On the whole the dental caries bacteria (Gram-positive and Gram-negative bacterial strains) were used. Negative control was prepared using discs impregnated with 10% DMSO in water and commercially available Gentamicin from Alkom Laboratories LTD was used as positive reference standards for all bacterial strains. In acute toxicity test, mice received doses of extract (acetone/water extract) from Sida urens L. by intraperitoneal route and LD50 was determined in Swiss mice. As for analgesic effects, acetic acid writhing method was used in mice. The acetic acid-induced writhing method was used in mice with aim to study analgesic effects. The results showed that the highest antibacterial activities were founded with the polyphenol-rich fractions against all bacterial strains compared to the standard antibiotic. About preliminary study in acute toxicity test, LD50 value obtained was more than 5000 mg/kg b.w. Polyphenol-rich fractions produced significant analgesic effects in acetic acid-induced writhing method and in a dose-dependent inhibition was observed. These results validate the ethno-botanical use of Sida urens L. (Malvaceae) and demonstrate the potential of this herbaceous as a potential antibacterial agent

  4. EVALUATION OF THE TEA TREE OIL ACTIVITY TO ANAEROBIC BACTERIA--IN VITRO STUDY.

    Science.gov (United States)

    Ziółkowska-Klinkosz, Marta; Kedzia, Anna; Meissner, Hhenry O; Kedzia, Andrzej W

    2016-01-01

    The study of the sensitivity to tea tree oil (Australian Company TTD International Pty. Ltd. Sydney) was carried out on 193 strains of anaerobic bacteria isolated from patients with various infections within the oral cavity and respiratory tracts. The susceptibility (MIC) of anaerobes was determined by means of plate dilution technique in Brucella agar supplemented with 5% defibrinated sheep blood, menadione and hemin. Inoculum contained 10(5) CFU per spot was cultured with Steers replicator upon the surface of agar with various tea tree oil concentrations or without oil (anaerobes growth control). Incubation the plates was performed in anaerobic jars under anaerobic conditions at 37 degrees C for 48 h. MIC was defined as the lowest concentrations of the essential oil completely inhibiting growth of anaerobic bacteria. Test results indicate, that among Gram-negative bacteria the most sensitive to essential oil were strains of Veillonella and Porphyromonas species. Essential oil in low concentrations (MIC in the range of = 0.12 - 0.5 mg/mL) inhibited growth of accordingly 80% and 68% strains. The least sensitive were strains of the genus Tannerella, Parabacteroides and Dialister (MIC 1.0 - 2.0 mg/mL). In the case of Gram-positive anaerobic bacteria the tea tree oil was the most active to strains of cocci of the genus Anaerococcus and Ruminococcus (MIC in range = 0.12 - 0.5 mg/mL) or strains of rods of the genus Eubacterium and Eggerthella (MIC = 0.25 mg/mL). Among Gram-positive rods the least sensitive were the strains of the genus Bifidobacterium ( MIC = 2.0 mg/mL). The tea tree oil was more active to Gram-positive than to Gram-negative anaerobic bacteria.

  5. Cell lysis and superoxide dismutase activities of highly radioresistant bacteria

    International Nuclear Information System (INIS)

    Yoshinaka, Taeko; Yano, Keiji; Yamaguchi, Hikoyuki

    1976-01-01

    The highly radioresistant bacterium, Arthrobacter radiotolerans, has been isolated from the radioactive hot spring of Misasa, and it does not sporulate, it is Gram-positive, and its color is pink to red. This bacterium shows the highest resistance to gamma-ray among Gram-positive resistants, but the lytic enzyme capable of lysing the cells of strong radioresistants and the surface structure of the cells are little known except those about Micrococcus radiodurans. The cells of the M. radiodurans can be lysed by Achramobacter lyticus enzyme, and electron microscopic observation and chemical analysis revealed the mutilayered surface structure of the cells consisting of an inner membrane, a mucopeptide wall layer and a very outer layer. The superoxide dismutase (SOD) activity of aerobic and anaerobic bacteria was studied, and the relatively high SOD activity of the M. radiodurans was found. The SOD function acts against the threat posed by the reactive superoxide radical being generated biologically, photochemically and radiochemically in the presence of molecular oxygen. In this paper, it is reported that the lytic enzyme No.2 obtained from Cytophaga sp., containing N-acetyl-muramyl-L-alanine amidase, peptidase and endopeptidase, and showing broad lytic spectra, was able to lyse the cells of A. radiotolerans and four radioresistant micrococci, and the radioresistant bacteria showed relatively high SOD activity except M. sp. 248. It is well known that superoxide anions are generated by aerobic irradiation, and are toxic to microbial cells. (Kako, I.)

  6. Cell lysis and superoxide dismutase activities of highly radioresistant bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinaka, T; Yano, K; Yamaguchi, H [Tokyo Univ. (Japan). Faculty of Agriculture

    1976-01-01

    The highly radioresistant bacterium, Arthrobacter radiotolerans, has been isolated from the radioactive hot spring of Misasa, and it does not sporulate, it is Gram-positive, and its color is pink to red. This bacterium shows the highest resistance to gamma-ray among Gram-positive resistants, but the lytic enzyme capable of lysing the cells of strong radioresistants and the surface structure of the cells are little known except those about Micrococcus radiodurans. The cells of the M. radiodurans can be lysed by Achramobacter lyticus enzyme, and electron microscopic observation and chemical analysis revealed the mutilayered surface structure of the cells consisting of an inner membrane, a mucopeptide wall layer and a very outer layer. The superoxide dismutase (SOD) activity of aerobic and anaerobic bacteria was studied, and the relatively high SOD activity of the M. radiodurans was found. The SOD function acts against the threat posed by the reactive superoxide radical being generated biologically, photochemically and radiochemically in the presence of molecular oxygen. In this paper, it is reported that the lytic enzyme No.2 obtained from Cytophaga sp., containing N-acetyl-muramyl-L-alanine amidase, peptidase and endopeptidase, and showing broad lytic spectra, was able to lyse the cells of A. radiotolerans and four radioresistant micrococci, and the radioresistant bacteria showedrelatively high SOD activity except M. sp. 248. It is well known that superoxide anions are generated by aerobic irradiation, and are toxic to microbial cells.

  7. A fragment of the alarmin prothymosin α as a novel biomarker in murine models of bacteria-induced sepsis.

    Science.gov (United States)

    Samara, Pinelopi; Miriagou, Vivi; Zachariadis, Michael; Mavrofrydi, Olga; Promponas, Vasilis J; Dedos, Skarlatos G; Papazafiri, Panagiota; Kalbacher, Hubert; Voelter, Wolfgang; Tsitsilonis, Ourania

    2017-07-25

    Sepsis is a life-threatening condition that requires urgent care. Thus, the identification of specific and sensitive biomarkers for its early diagnosis and management are of clinical importance. The alarmin prothymosin alpha (proTα) and its decapeptide proTα(100-109) are immunostimulatory peptides related to cell death. In this study, we generated bacterial models of sepsis in mice using two Klebsiella pneumoniae strains (L-78 and ATCC 43816) and monitored sepsis progression using proTα(100-109) as a biomarker. Serum concentration of proTα(100-109) gradually increased as sepsis progressed in mice infected with L-78, a strain which, unlike ATCC 43816, was phagocytosed by monocytes/macrophages. Analysis of splenocytes from L-78-infected animals revealed that post-infection spleen monocytes/macrophages were gradually driven to caspase-3-mediated apoptosis. These results were verified in vitro in L-78-infected human monocytes/macrophages. Efficient phagocytosis of L-78 by monocytes stimulated their apoptosis and the concentration of proTα(100-109) in culture supernatants increased. Human macrophages strongly phagocytosed L-78, but resisted cell death. This is the first report suggesting that high levels of proTα(100-109) correlate, both in vitro and in vivo, with increased percentages of cell apoptosis. Moreover, we showed that low levels of proTα(100-109) early post-infection likely correlate with sepsis resolution and thus, the decapeptide could eventually serve as an early surrogate biomarker for predicting bacteria-induced sepsis outcome.

  8. Immunomodulatory properties of probiotic bacteria

    DEFF Research Database (Denmark)

    Fink, Lisbeth Nielsen

    2007-01-01

    Certain lactic acid bacteria (LAB) are part of the commensal intestinal flora and considered beneficial for health, as they compete with pathogens for adhesion sites in the intestine and ferment otherwise indigestible compounds. Another important property of these so-called probiotic bacteria...... with bacteria, and the cytokine pattern induced by specific bacteria resembled the pattern induced in MoDC, except for TNF-alpha and IL-6, which were induced in response to different bacteria in blood DC/monocytes and monocyte-derived DC. Autologous NK cells produced IFN-gamma when cultured with blood DC......, monocytes and monocyte-derived DC and IL-12-inducing bacteria, whereas only DC induced IFN-gamma production in allogeneic T cells. In vitro-generated DC is a commonly used model of tissue DC, but they differ in certain aspects from intestinal DC, which are in direct contact with the intestinal microbiota...

  9. In vitro growth inhibition of mastitis causing bacteria by phenolics and metal chelators

    Energy Technology Data Exchange (ETDEWEB)

    Chew, B.P.; Tjoelker, L.W.; Tanaka, T.S.

    1985-11-01

    Antimicrobial activities of three phenolic compounds and four metal chelators were tested at 0, 250, 500, and 1000 ppm in vitro against four major mastitis-causing bacteria, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pnuemoniae, and Escherichia coli. Overall, butylated hydroxyanisole and tert-butylhydroquinone showed the greatest antimicrobial activity. These phenolics were bactericidal at 250 to 500 ppm against all four bacteria tested. The butylated hydroxytoluene was bactericidal against the gram-positive bacteria but was ineffective against the coliforms. At 250 ppm, disodium ethylenediaminetetraacetic acid was bactericidal against the gram-positive bacteria but much less effective against the gram-negatives. However, diethylene-triaminepentaacetic acid was more growth inhibitory than ethylenediaminetetraacetic acid against the gram-negative bacteria and especially against Escherichia coli. All other compounds were generally much less effective or ineffective against all four microorganisms. Therefore, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid may have practical implications in the prevention or treatment of bovine mastitis.

  10. Anti-bacterial effects of the essential oil of Teucrium polium L. on human pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Mohammad Mohammad

    2013-09-01

    Results: The total oil content of Teucrium polium plant was 0.75%. Twenty eight compounds were identified in the essential oil that included 99.75% of the total oil. The major components were α-pinene (12.52%, Linalool (10.63% and Caryophyllene oxide (9.69%. For study of antimicrobial activity of the oil sample, the essential oil was tested against 9 bacteria by disc diffusion method. The antimicrobial effects of this essential oil was determined against three Gram positive bacteria Staphylococcus areous (PTCC 1431, Staphylococcus epidermidis (PTCC 1436, Streptococcus faecalis (PTCC 1237; as well as six Gram negative bacteria Pseudomonas aeroginosa (PTCC 11430, Shigella flexneri (PTCC 1716, Kellebsiella pneuomonae(PTCC=1053, Salmonella typhi (PTCC=1609, Serratia marcescens (PTCC 1187 and Escherichia coli (PTCC 1533. The antimicrobial effects of this essential oil on the Gram positive bacteria ( Staphylococcus aureus and Staphylococcus epidermidis and on all the Gram negative bacteria tested was much higher than those observed by tetracycline. Conclusions: The results showed the essential oil of Teucrium polium had strong anti-bacterial effects. The relatively high contents of α-pinene and Linalool in the essential oil may be the cause of its potential medicinal effects

  11. Chip-based in situ hybridization for identification of bacteria from the human microbiome.

    Energy Technology Data Exchange (ETDEWEB)

    Light, Yooli Kim; Meagher, Robert J.; Singh, Anup K.; Liu, Peng

    2010-11-01

    The emerging field of metagenomics seeks to assess the genetic diversity of complex mixed populations of bacteria, such as those found at different sites within the human body. A single person's mouth typically harbors up to 100 bacterial species, while surveys of many people have found more than 700 different species, of which {approx}50% have never been cultivated. In typical metagenomics studies, the cells themselves are destroyed in the process of gathering sequence information, and thus the connection between genotype and phenotype is lost. A great deal of sequence information may be generated, but it is impossible to assign any given sequence to a specific cell. We seek non-de