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Sample records for bacterial defensin resistance

  1. A Defensin from the Model Beetle Tribolium castaneum Acts Synergistically with Telavancin and Daptomycin against Multidrug Resistant Staphylococcus aureus.

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    Rajmohan Rajamuthiah

    Full Text Available The red flour beetle Tribolium castaneum is a common insect pest and has been established as a model beetle to study insect development and immunity. This study demonstrates that defensin 1 from T. castaneum displays in vitro and in vivo antimicrobial activity against drug resistant Staphylococcus aureus strains. The minimum inhibitory concentration (MIC of defensin 1 against 11 reference and clinical staphylococcal isolates was between 16-64 μg/ml. The putative mode of action of the defensin peptide is disruption of the bacterial cell membrane. The antibacterial activity of defensin 1 was attenuated by salt concentrations of 1.56 mM and 25 mM for NaCl and CaCl2 respectively. Treatment of defensin 1 with the reducing agent dithiothreitol (DTT at concentrations 1.56 to 3.13 mM abolished the antimicrobial activity of the peptide. In the presence of subinhibitory concentrations of antibiotics that also target the bacterial cell envelope such as telavancin and daptomycin, the MIC of the peptide was as low as 1 μg/ml. Moreover, when tested against an S. aureus strain that was defective in D-alanylation of the cell wall, the MIC of the peptide was 0.5 μg/ml. Defensin 1 exhibited no toxicity against human erythrocytes even at 400 μg/ml. The in vivo activity of the peptide was validated in a Caenorhabditis elegans-MRSA liquid infection assay. These results suggest that defensin 1 behaves similarly to other cationic AMPs in its mode of action against S. aureus and that the activity of the peptide can be enhanced in combination with other antibiotics with similar modes of action or with compounds that have the ability to decrease D-alanylation of the bacterial cell wall.

  2. A Defensin from the Model Beetle Tribolium castaneum Acts Synergistically with Telavancin and Daptomycin against Multidrug Resistant Staphylococcus aureus.

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    Rajamuthiah, Rajmohan; Jayamani, Elamparithi; Conery, Annie L; Fuchs, Beth Burgwyn; Kim, Wooseong; Johnston, Tatiana; Vilcinskas, Andreas; Ausubel, Frederick M; Mylonakis, Eleftherios

    2015-01-01

    The red flour beetle Tribolium castaneum is a common insect pest and has been established as a model beetle to study insect development and immunity. This study demonstrates that defensin 1 from T. castaneum displays in vitro and in vivo antimicrobial activity against drug resistant Staphylococcus aureus strains. The minimum inhibitory concentration (MIC) of defensin 1 against 11 reference and clinical staphylococcal isolates was between 16-64 μg/ml. The putative mode of action of the defensin peptide is disruption of the bacterial cell membrane. The antibacterial activity of defensin 1 was attenuated by salt concentrations of 1.56 mM and 25 mM for NaCl and CaCl2 respectively. Treatment of defensin 1 with the reducing agent dithiothreitol (DTT) at concentrations 1.56 to 3.13 mM abolished the antimicrobial activity of the peptide. In the presence of subinhibitory concentrations of antibiotics that also target the bacterial cell envelope such as telavancin and daptomycin, the MIC of the peptide was as low as 1 μg/ml. Moreover, when tested against an S. aureus strain that was defective in D-alanylation of the cell wall, the MIC of the peptide was 0.5 μg/ml. Defensin 1 exhibited no toxicity against human erythrocytes even at 400 μg/ml. The in vivo activity of the peptide was validated in a Caenorhabditis elegans-MRSA liquid infection assay. These results suggest that defensin 1 behaves similarly to other cationic AMPs in its mode of action against S. aureus and that the activity of the peptide can be enhanced in combination with other antibiotics with similar modes of action or with compounds that have the ability to decrease D-alanylation of the bacterial cell wall.

  3. Staphylococcus aureus resistance to human defensins and evasion of neutrophil killing via the novel virulence factor MprF is based on modification of membrane lipids with L-lysine

    NARCIS (Netherlands)

    Peschel, A.; Jack, R.W.; Otto, M.; Collins, L.V.; Staubitz, P.; Nicholson, G.; Kalbacher, H.; Nieuwenhuizen, W.F.; Jung, G.; Tarkowski, A.; Kessel, K.P.M. van; Strijp, J.A.G. van

    2001-01-01

    Defensins, antimicrobial peptides of the innate immune system, protect human mucosal epithelia and skin against microbial infections and are produced in large amounts by neutrophils. The bacterial pathogen Staphylococcus aureus is insensitive to defensins by virtue of an unknown resistance mechanism

  4. Phosphoethanolamine Transferase LptA in Haemophilus ducreyi Modifies Lipid A and Contributes to Human Defensin Resistance In Vitro.

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    Michael P Trombley

    Full Text Available Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs, including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to LL-37, mediated by the sensitive to antimicrobial peptide (Sap transporter, is required for H. ducreyi virulence in humans. Cationic APs are attracted to the negatively charged bacterial cell surface. In other gram-negative bacteria, modification of lipopolysaccharide or lipooligosaccharide (LOS by the addition of positively charged moieties, such as phosphoethanolamine (PEA, confers AP resistance by means of electrostatic repulsion. H. ducreyi LOS has PEA modifications at two sites, and we identified three genes (lptA, ptdA, and ptdB in H. ducreyi with homology to a family of bacterial PEA transferases. We generated non-polar, unmarked mutants with deletions in one, two, or all three putative PEA transferase genes. The triple mutant was significantly more susceptible to both α- and β-defensins; complementation of all three genes restored parental levels of AP resistance. Deletion of all three PEA transferase genes also resulted in a significant increase in the negativity of the mutant cell surface. Mass spectrometric analysis revealed that LptA was required for PEA modification of lipid A; PtdA and PtdB did not affect PEA modification of LOS. In human inoculation experiments, the triple mutant was as virulent as its parent strain. While this is the first identified mechanism of resistance to α-defensins in H. ducreyi, our in vivo data suggest that resistance to cathelicidin LL-37 may be more important than defensin resistance to H. ducreyi pathogenesis.

  5. Phosphoethanolamine Transferase LptA in Haemophilus ducreyi Modifies Lipid A and Contributes to Human Defensin Resistance In Vitro.

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    Trombley, Michael P; Post, Deborah M B; Rinker, Sherri D; Reinders, Lorri M; Fortney, Kate R; Zwickl, Beth W; Janowicz, Diane M; Baye, Fitsum M; Katz, Barry P; Spinola, Stanley M; Bauer, Margaret E

    2015-01-01

    Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs), including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to LL-37, mediated by the sensitive to antimicrobial peptide (Sap) transporter, is required for H. ducreyi virulence in humans. Cationic APs are attracted to the negatively charged bacterial cell surface. In other gram-negative bacteria, modification of lipopolysaccharide or lipooligosaccharide (LOS) by the addition of positively charged moieties, such as phosphoethanolamine (PEA), confers AP resistance by means of electrostatic repulsion. H. ducreyi LOS has PEA modifications at two sites, and we identified three genes (lptA, ptdA, and ptdB) in H. ducreyi with homology to a family of bacterial PEA transferases. We generated non-polar, unmarked mutants with deletions in one, two, or all three putative PEA transferase genes. The triple mutant was significantly more susceptible to both α- and β-defensins; complementation of all three genes restored parental levels of AP resistance. Deletion of all three PEA transferase genes also resulted in a significant increase in the negativity of the mutant cell surface. Mass spectrometric analysis revealed that LptA was required for PEA modification of lipid A; PtdA and PtdB did not affect PEA modification of LOS. In human inoculation experiments, the triple mutant was as virulent as its parent strain. While this is the first identified mechanism of resistance to α-defensins in H. ducreyi, our in vivo data suggest that resistance to cathelicidin LL-37 may be more important than defensin resistance to H. ducreyi pathogenesis.

  6. Plectasin, a Fungal Defensin, Targets the Bacterial Cell Wall Precursor Lipid II

    DEFF Research Database (Denmark)

    Schneider, Tanja; Kruse, Thomas; Wimmer, Reinhard

    2010-01-01

    that plectasin, a fungal defensin, acts by directly binding the bacterial cell-wall precursor Lipid II. A wide range of genetic and biochemical approaches identify cell-wall biosynthesis as the pathway targeted by plectasin. In vitro assays for cell-wall synthesis identified Lipid II as the specific cellular...

  7. Combining Flagellin and human β-defensin-3 to combat bacterial Infections

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    Ofra eSabag

    2014-12-01

    Full Text Available The discovery and therapeutic use of antibiotics made a major contribution to the reduction of human morbidity and mortality. However, the growing resistance to antibiotics has become a matter of huge concern. In this study we aimed to develop an innovative approach to treat bacterial infections utilizing two components: the human antibacterial peptide β-defensin-3 (BD3 and the bacterial protein flagellin (F. This combination was designed to provide an efficient weapon against bacterial infections with the peptide killing the bacteria directly, while the flagellin protein triggers the immune system and acts against bacteria escaping from the peptide’s action. We designed, expressed and purified the fusion protein FBD3 and its two components, the F protein and the native BD3 peptide. FBD3 fusion protein and native BD3 peptide had antibacterial activity in vitro against various bacterial strains. FBD3 and F proteins could also recognize their receptor expressed on target cells and stimulated secretion of IL-8. In addition, F and FBD3 proteins had a partial protective effect in mice infected by pathogenic E. coli bacteria that cause a lethal disease. Moreover, we were able to show partial protection of mice infected with E. coli using a flagellin sequence from Salmonella.We also explored flagellin’s basic mechanisms of action, focusing on its effects on CD4+ T cells from healthy donors. We found that F stimulation caused an increase in the mRNA levels of the Th1 response cytokines IL12A and IFNγ. In addition, F stimulation affected its own receptor.

  8. Defensins: antifungal lessons from eukaryotes

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    Patrícia M. Silva

    2014-03-01

    Full Text Available Over the last years, antimicrobial peptides (AMPs have been the focus of intense research towards the finding of a viable alternative to current antifungal drugs. Defensins are one of the major families of AMPs and the most represented among all eukaryotic groups, providing an important first line of host defense against pathogenic microorganisms. Several of these cysteine-stabilized peptides present a relevant effect against fungi. Defensins are the AMPs with the broader distribution across all eukaryotic kingdoms, namely, Fungi, Plantæ and Animalia, and were recently shown to have an ancestor in a bacterial organism. As a part of the host defense, defensins act as an important vehicle of information between innate and adaptive immune system and have a role in immunomodulation. This multidimensionality represents a powerful host shield, hard for microorganisms to overcome using single approach resistance strategies. Pathogenic fungi resistance to conventional antimycotic drugs is becoming a major problem. Defensins, as other AMPs, have shown to be an effective alternative to the current antimycotic therapies, demonstrating potential as novel therapeutic agents or drug leads. In this review, we summarize the current knowledge on some eukaryotic defensins with antifungal action. An overview of the main targets in the fungal cell and the mechanism of action of these AMPs (namely, the selectivity for some fungal membrane components are presented. Additionally, recent works on antifungal defensins structure, activity and citotoxicity are also reviewed.

  9. Stable integration and expression of a plant defensin in tomato confers resistance to fusarium wilt.

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    Abdallah, Naglaa A; Shah, Dilip; Abbas, Dina; Madkour, Magdy

    2010-01-01

    Plant defensins are small cysteine-rich peptides which belong to a group of pathogenasis related defense mechanism proteins. The proteins inhibit the growth of a broad range of microbes and are highly stable under extreme environmental stresses. Tomato cultivation is affected by fungal disease such as Fusarium wilt. In order to overcome fungal damages, transgenic tomato plants expressing the Medicago sativa defensin gene MsDef1 under the control of the CaMV 35S promoter were developed. The Fusarium-susceptible tomato (Lycobersicum esculentum Mill) cultivar CastleRock was used for transformation to acquire fungal resistance. Hypocotyl with a part of cotyledon (hypocotyledonary) for young tomato seedlings were used as an explant material and transformation was performed using the biolistic delivery system. Bombarded shoots were selected on regeneration medium supplemented with hygromycin and suitable concentrations of BA, zeatin ripozide and AgNO(3). Putative transgenic plantlets of T(0) were confirmed by PCR analysis using primers specific for the transgene and the transformation frequency obtained was 52.3%. Transformation and transcription of transgenes were confirmed in T(1) by PCR, Southern hybridizations, and reverse-transcription PCR (RT-PCR). The copy numbers of integrated transgene into tomato genome ranged between 1-3 copies. Greenhouse bioassay was performed on the transgenic T(1) and T(2) young seedlings and non-transgenic controls by challenging with a vigorous isolate of the fungal pathogen Fusarium oxysporum f. sp. Lycopersici. The level of fungal infectivity was determined using RT-PCR with tomatinase specific primers. Transgenic lines were more resistant to infection by fusarium than the control plants. These results indicated that overexpressing defensins in transgenic plants confer resistance to fungal pathogens.

  10. Petunia floral defensins with unique prodomains as novel candidates for development of fusarium wilt resistance in transgenic banana plants.

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    Siddhesh B Ghag

    Full Text Available Antimicrobial peptides are a potent group of defense active molecules that have been utilized in developing resistance against a multitude of plant pathogens. Floral defensins constitute a group of cysteine-rich peptides showing potent growth inhibition of pathogenic filamentous fungi especially Fusarium oxysporum in vitro. Full length genes coding for two Petunia floral defensins, PhDef1 and PhDef2 having unique C-terminal 31 and 27 amino acid long predicted prodomains, were overexpressed in transgenic banana plants using embryogenic cells as explants for Agrobacterium-mediated genetic transformation. High level constitutive expression of these defensins in elite banana cv. Rasthali led to significant resistance against infection of Fusarium oxysporum f. sp. cubense as shown by in vitro and ex vivo bioassay studies. Transgenic banana lines expressing either of the two defensins were clearly less chlorotic and had significantly less infestation and discoloration in the vital corm region of the plant as compared to untransformed controls. Transgenic banana plants expressing high level of full-length PhDef1 and PhDef2 were phenotypically normal and no stunting was observed. In conclusion, our results suggest that high-level constitutive expression of floral defensins having distinctive prodomains is an efficient strategy for development of fungal resistance in economically important fruit crops like banana.

  11. The cold-induced defensin TAD1 confers resistance against snow mold and Fusarium head blight in transgenic wheat.

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    Sasaki, Kentaro; Kuwabara, Chikako; Umeki, Natsuki; Fujioka, Mari; Saburi, Wataru; Matsui, Hirokazu; Abe, Fumitaka; Imai, Ryozo

    2016-06-20

    TAD1 (Triticum aestivum defensin 1) is induced during cold acclimation in winter wheat and encodes a plant defensin with antimicrobial activity. In this study, we demonstrated that recombinant TAD1 protein inhibits hyphal growth of the snow mold fungus, Typhula ishikariensis in vitro. Transgenic wheat plants overexpressing TAD1 were created and tested for resistance against T. ishikariensis. Leaf inoculation assays revealed that overexpression of TAD1 confers resistance against the snow mold. In addition, the TAD1-overexpressors showed resistance against Fusarium graminearum, which causes Fusarium head blight, a devastating disease in wheat and barley. These results indicate that TAD1 is a candidate gene to improve resistance against multiple fungal diseases in cereal crops.

  12. The Unusual Resistance of Avian Defensin AvBD7 to Proteolytic Enzymes Preserves Its Antibacterial Activity

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    Bailleul, Geoffrey; Kravtzoff, Amanda; Joulin-Giet, Alix; Lecaille, Fabien; Labas, Valérie; Meudal, Hervé; Loth, Karine; Teixeira-Gomes, Ana-Paula; Gilbert, Florence B.; Coquet, Laurent; Jouenne, Thierry; Brömme, Dieter; Schouler, Catherine; Landon, Céline; Lalmanach, Gilles; Lalmanach, Anne-Christine

    2016-01-01

    Defensins are frontline peptides of mucosal immunity in the animal kingdom, including birds. Their resistance to proteolysis and their ensuing ability to maintain antimicrobial potential remains questionable and was therefore investigated. We have shown by bottom-up mass spectrometry analysis of protein extracts that both avian beta-defensins AvBD2 and AvBD7 were ubiquitously distributed along the chicken gut. Cathepsin B was found by immunoblotting in jejunum, ileum, caecum, and caecal tonsils, while cathepsins K, L, and S were merely identified in caecal tonsils. Hydrolysis product of AvBD2 and AvBD7 incubated with a panel of proteases was analysed by RP-HPLC, mass spectrometry and antimicrobial assays. AvBD2 and AvBD7 were resistant to serine proteases and to cathepsins D and H. Conversely cysteine cathepsins B, K, L, and S degraded AvBD2 and abolished its antibacterial activity. Only cathepsin K cleaved AvBD7 and released Ile4-AvBD7, a N-terminal truncated natural peptidoform of AvBD7 that displayed antibacterial activity. Besides the 3-stranded antiparallel beta-sheet typical of beta-defensins, structural analysis of AvBD7 by two-dimensional NMR spectroscopy highlighted the restricted accessibility of the C-terminus embedded by the N-terminal region and gave a formal evidence of a salt bridge (Asp9-Arg12) that could account for proteolysis resistance. The differential susceptibility of avian defensins to proteolysis opens intriguing questions about a distinctive role in the mucosal immunity against pathogen invasion. PMID:27561012

  13. Overexpression of a defensin enhances resistance to a fruit-specific anthracnose fungus in pepper.

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    Hyo-Hyoun Seo

    Full Text Available Functional characterization of a defensin, J1-1, was conducted to evaluate its biotechnological potentiality in transgenic pepper plants against the causal agent of anthracnose disease, Colletotrichum gloeosporioides. To determine antifungal activity, J1-1 recombinant protein was generated and tested for the activity against C. gloeosporioides, resulting in 50% inhibition of fungal growth at a protein concentration of 0.1 mg·mL-1. To develop transgenic pepper plants resistant to anthracnose disease, J1-1 cDNA under the control of 35S promoter was introduced into pepper via Agrobacterium-mediated genetic transformation method. Southern and Northern blot analyses confirmed that a single copy of the transgene in selected transgenic plants was normally expressed and also stably transmitted to subsequent generations. The insertion of T-DNA was further analyzed in three independent homozygous lines using inverse PCR, and confirmed the integration of transgene in non-coding region of genomic DNA. Immunoblot results showed that the level of J1-1 proteins, which was not normally accumulated in unripe fruits, accumulated high in transgenic plants but appeared to differ among transgenic lines. Moreover, the expression of jasmonic acid-biosynthetic genes and pathogenesis-related genes were up-regulated in the transgenic lines, which is co-related with the resistance of J1-1 transgenic plants to anthracnose disease. Consequently, the constitutive expression of J1-1 in transgenic pepper plants provided strong resistance to the anthracnose fungus that was associated with highly reduced lesion formation and fungal colonization. These results implied the significance of the antifungal protein, J1-1, as a useful agronomic trait to control fungal disease.

  14. Characterization of Cimex lectularius (bedbug) defensin peptide and its antimicrobial activity against human skin microflora.

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    Kaushal, Akanksha; Gupta, Kajal; van Hoek, Monique L

    2016-02-19

    Antimicrobial peptides are components of both vertebrate and invertebrate innate immune systems that are expressed in response to exposure to bacterial antigens. Naturally occurring antimicrobial peptides from evolutionarily ancient species have been extensively studied and are being developed as potential therapeutics against antibiotic resistant microorganisms. In this study, a putative Cimex lectularius (bedbug, CL) defensin is characterized for its effectiveness against human skin flora including Gram-negative and Gram-positive bacteria. The bedbug defensin (CL-defensin), belonging to family of insect defensins, is predicted to have a characteristic N-terminal loop, an α-helix, and an antiparallel β-sheet, which was supported by circular dichroism spectroscopy. The defensin was shown to be antimicrobial against Gram-positive bacteria commonly found on human skin (Micrococcus luteus, Corynebacterium renale, Staphylococcus aureus and Staphylococcus epidermidis); however, it was ineffective against common skin Gram-negative bacteria (Pseudomonas aeruginosa and Acinetobacter baumannii) under low-salt conditions. CL-defensin was also effective against M. luteus and C. renale in high-salt (MIC) conditions. Our studies indicate that CL-defensin functions by depolarization and pore-formation in the bacterial cytoplasmic membrane.

  15. Copy number variation of the beta defensin gene cluster on chromosome 8p influences the bacterial microbiota within the nasopharynx of otitis-prone children.

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    Jones, Eric A; Kananurak, Anchasa; Bevins, Charles L; Hollox, Edward J; Bakaletz, Lauren O

    2014-01-01

    As there is increasing evidence that aberrant defensin expression is related to susceptibility for infectious disease and inflammatory disorders, we sought to determine if copy number of the beta-defensin gene cluster located on chromosome 8p23.1 (DEFB107, 106, 105, 104, 103, DEFB4 and SPAG11), that shows copy number variation as a block, was associated with susceptibility to otitis media (OM). The gene DEFB103 within this complex encodes human beta defensin-3 (hBD-3), an antimicrobial peptide (AP) expressed by epithelial cells that line the mammalian airway, important for defense of mucosal surfaces and previously shown to have bactericidal activity in vitro against multiple human pathogens, including the three that predominate in OM. To this end, we conducted a retrospective case-control study of 113 OM prone children and 267 controls aged five to sixty months. We identified the copy number of the above defined beta-defensin gene cluster (DEFB-CN) in each study subject by paralogue ratio assays. The mean DEFB-CN was indistinguishable between subjects classified as OM prone based on a recent history of multiple episodes of OM and control subjects who had no history of OM (4.4 ± 0.96 versus 4.4 ± 1.08, respectively: Odds Ratio [OR]: 1.16 (95% CI: 0.61, 2.20). Despite a lack of direct association, we observed a statistically significant correlation between DEFB-CN and nasopharyngeal bacterial colonization patterns. Collectively, our findings suggested that susceptibility to OM might be mediated by genetic variation among individuals, wherein a DEFB-CN less than 4 exerts a marked influence on the microbiota of the nasopharynx, specifically with regard to colonization by the three predominant bacterial pathogens of OM.

  16. Copy number variation of the beta defensin gene cluster on chromosome 8p influences the bacterial microbiota within the nasopharynx of otitis-prone children.

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    Eric A Jones

    Full Text Available As there is increasing evidence that aberrant defensin expression is related to susceptibility for infectious disease and inflammatory disorders, we sought to determine if copy number of the beta-defensin gene cluster located on chromosome 8p23.1 (DEFB107, 106, 105, 104, 103, DEFB4 and SPAG11, that shows copy number variation as a block, was associated with susceptibility to otitis media (OM. The gene DEFB103 within this complex encodes human beta defensin-3 (hBD-3, an antimicrobial peptide (AP expressed by epithelial cells that line the mammalian airway, important for defense of mucosal surfaces and previously shown to have bactericidal activity in vitro against multiple human pathogens, including the three that predominate in OM. To this end, we conducted a retrospective case-control study of 113 OM prone children and 267 controls aged five to sixty months. We identified the copy number of the above defined beta-defensin gene cluster (DEFB-CN in each study subject by paralogue ratio assays. The mean DEFB-CN was indistinguishable between subjects classified as OM prone based on a recent history of multiple episodes of OM and control subjects who had no history of OM (4.4 ± 0.96 versus 4.4 ± 1.08, respectively: Odds Ratio [OR]: 1.16 (95% CI: 0.61, 2.20. Despite a lack of direct association, we observed a statistically significant correlation between DEFB-CN and nasopharyngeal bacterial colonization patterns. Collectively, our findings suggested that susceptibility to OM might be mediated by genetic variation among individuals, wherein a DEFB-CN less than 4 exerts a marked influence on the microbiota of the nasopharynx, specifically with regard to colonization by the three predominant bacterial pathogens of OM.

  17. Anti-bacterial activity of recombinant human β-defensin-3 secreted in the milk of transgenic goats produced by somatic cell nuclear transfer.

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    Liu, Jun; Luo, Yan; Ge, Hengtao; Han, Chengquan; Zhang, Hui; Wang, Yongsheng; Su, Jianmin; Quan, Fusheng; Gao, Mingqing; Zhang, Yong

    2013-01-01

    The present study was conducted to determine whether recombinant human β-defensin-3 (rHBD3) in the milk of transgenic goats has an anti-bacterial activity against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Streptococcus agalactiae (S. agalactiae) that could cause mastitis. A HBD3 mammary-specific expression vector was transfected by electroporation into goat fetal fibroblasts which were used to produce fourteen healthy transgenic goats by somatic cell nuclear transfer. The expression level of rHBD3 in the milk of the six transgenic goats ranged from 98 to 121 µg/ml at 15 days of lactation, and was maintained at 90-111 µg/ml during the following 2 months. Milk samples from transgenic goats showed an obvious inhibitory activity against E. coli, S. aureus and S. agalactiae in vitro. The minimal inhibitory concentrations of rHBD3 in milk against E. coli, S. aureus and S. agalactiae were 9.5-10.5, 21.8-23.0 and 17.3-18.5 µg/mL, respectively, which was similar to those of the HBD3 standard (P>0.05). The in vivo anti-bacterial activities of rHBD3 in milk were examined by intramammary infusion of viable bacterial inoculums. We observed that 9/10 and 8/10 glands of non-transgenic goats infused with S. aureus and E. coli became infected. The mean numbers of viable bacteria went up to 2.9×10(3) and 95.4×10(3) CFU/ml at 48 h after infusion, respectively; the mean somatic cell counts (SCC) in infected glands reached up to 260.4×10(5) and 622.2×10(5) cells/ml, which were significantly higher than the SCC in uninfected goat glands. In contrast, no bacteria was presented in glands of transgenic goats and PBS-infused controls, and the SSC did not significantly change throughout the period. Moreover, the compositions and protein profiles of milk from transgenic and non-transgenic goats were identical. The present study demonstrated that HBD3 were an effective anti-bacterial protein to enhance the mastitis resistance of dairy animals.

  18. Anti-bacterial activity of recombinant human β-defensin-3 secreted in the milk of transgenic goats produced by somatic cell nuclear transfer.

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    Jun Liu

    Full Text Available The present study was conducted to determine whether recombinant human β-defensin-3 (rHBD3 in the milk of transgenic goats has an anti-bacterial activity against Escherichia coli (E. coli, Staphylococcus aureus (S. aureus and Streptococcus agalactiae (S. agalactiae that could cause mastitis. A HBD3 mammary-specific expression vector was transfected by electroporation into goat fetal fibroblasts which were used to produce fourteen healthy transgenic goats by somatic cell nuclear transfer. The expression level of rHBD3 in the milk of the six transgenic goats ranged from 98 to 121 µg/ml at 15 days of lactation, and was maintained at 90-111 µg/ml during the following 2 months. Milk samples from transgenic goats showed an obvious inhibitory activity against E. coli, S. aureus and S. agalactiae in vitro. The minimal inhibitory concentrations of rHBD3 in milk against E. coli, S. aureus and S. agalactiae were 9.5-10.5, 21.8-23.0 and 17.3-18.5 µg/mL, respectively, which was similar to those of the HBD3 standard (P>0.05. The in vivo anti-bacterial activities of rHBD3 in milk were examined by intramammary infusion of viable bacterial inoculums. We observed that 9/10 and 8/10 glands of non-transgenic goats infused with S. aureus and E. coli became infected. The mean numbers of viable bacteria went up to 2.9×10(3 and 95.4×10(3 CFU/ml at 48 h after infusion, respectively; the mean somatic cell counts (SCC in infected glands reached up to 260.4×10(5 and 622.2×10(5 cells/ml, which were significantly higher than the SCC in uninfected goat glands. In contrast, no bacteria was presented in glands of transgenic goats and PBS-infused controls, and the SSC did not significantly change throughout the period. Moreover, the compositions and protein profiles of milk from transgenic and non-transgenic goats were identical. The present study demonstrated that HBD3 were an effective anti-bacterial protein to enhance the mastitis resistance of dairy animals.

  19. 防御素的生物学特性及其抗病基因工程%Biological characteristics of defensin and its disease-resistance genetic engineering

    Institute of Scientific and Technical Information of China (English)

    付蓝宝; 于嘉林; 刘伟华

    2011-01-01

    防御素是一种富含半胱氨酸的小分子多肽,对细菌等微生物具有广谱抗性,且作用机制特殊.迄今为止,国内外在防御素方面进行了大量的研究,已经从各类生物体中分离出不同种类的防御素.并在基因工程和医药领域呈现广泛的应用前景.文章对防御素的分类、生物学特性,包括哺乳动物α-、β-、θ-防御素、昆虫以及植物防御素的分子结构及抗菌活性进行了综述,阐述了防御素的膜作用及与细胞内复合物结合的作用机制.总结和归纳了防御素基因的分离、表达研究进展及动、植物防御素基因在抗病基因工程领域的应用,并对防御素在未来的生物制药和植物抗病基因工程方面的应用前景进行了展望.%Defensin is a kind of cysteine-rich small peptide, which has a broad spectrum of resistance to bacteria with a special resistance mechanism.So far, a large number of studies on defensins have been reported, and the different types of defensins have been isolated from various organisms.A broad prospect of application on defensins has been displayed both in genetic engineering and medicine field.This article reviewed the classification and the biological characteristics of defensins, including mammalian α-, β-, θ-defensins, insect defensins, and plant defensins.The molecular structures,antibacterial activities, and antibacterial mechanisms of these definsins were summarized.The two mechanisms of defensin, including independent membrane mechanism and targeting of intracellular compounds by defensins, are expounded.This paper also summarized the researches on isolation and expression of defensin genes and disease resistance genetic engineering of mammal and plant defensins.A prospect of the future applications of defensin both in biopharmaceutical sciences and plant disease resistance genetic engineering was discussed.

  20. The Interplay between Defensins and Microbiota in Crohn's Disease

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    Coretti, Lorena; Natale, Alessandro; Cuomo, Mariella; Florio, Ermanno; Keller, Simona

    2017-01-01

    Crohn's disease (CD) is a chronic inflammation of the intestinal mucosa, characterized by periods of acute recurrence and remission. Depending on the specific region affected, CD is classified as ileal CD or colonic CD. It is largely accepted that the intestinal microbiota is involved in the onset of the pathology. Indeed, a reduced immune tolerance to components of the intestinal commensal microbiota and inflammation of the intestinal barrier typifies patients with CD. Several studies have shown defective expression of intestinal antimicrobial peptides (AMPs) in patients with CD compared to controls, particularly defensins. A reduction in α-defensins is observed in ileal CD, while β-defensins are increased in colonic CD. In addition to an immunological basis, the disease is frequently associated with genetic alterations including mutations of NOD2 gene. Several therapeutic strategies to circumvent the dysfunction observed in CD are currently under investigation. These include the use of delivery systems to administer endogenous AMPs and the engineering of peptidomimetics that could ameliorate the severity of CD. In this review, the role defensins play in CD and the strategies aimed at overcoming bacterial resistance will be discussed. PMID:28246439

  1. Modelling study of dimerization in mammalian defensins

    Directory of Open Access Journals (Sweden)

    Verma Chandra

    2006-12-01

    Full Text Available Abstract Background Defensins are antimicrobial peptides of innate immunity functioning by non-specific binding to anionic phospholipids in bacterial membranes. Their cationicity, amphipathicity and ability to oligomerize are considered key factors for their action. Based on structural information on human β-defensin 2, we examine homologous defensins from various mammalian species for conserved functional physico-chemical characteristics. Results Based on homology greater than 40%, structural models of 8 homologs of HBD-2 were constructed. A conserved pattern of electrostatics and dynamics was observed across 6 of the examined defensins; models backed by energetics suggest that the defensins in these 6 organisms are characterized by dimerization-linked enhanced functional potentials. In contrast, dimerization is not energetically favoured in the sheep, goat and mouse defensins, suggesting that they function efficiently as monomers. Conclusion β-defensin 2 from some mammals may work as monomers while those in others, including humans, work as oligomers. This could potentially be used to design human defensins that may be effective at lower concentrations and hence have therapeutic benefits.

  2. Insight into invertebrate defensin mechanism of action: oyster defensins inhibit peptidoglycan biosynthesis by binding to lipid II.

    Science.gov (United States)

    Schmitt, Paulina; Wilmes, Miriam; Pugnière, Martine; Aumelas, André; Bachère, Evelyne; Sahl, Hans-Georg; Schneider, Tanja; Destoumieux-Garzón, Delphine

    2010-09-17

    Three oyster defensin variants (Cg-Defh1, Cg-Defh2, and Cg-Defm) were produced as recombinant peptides and characterized in terms of activities and mechanism of action. In agreement with their spectrum of activity almost specifically directed against Gram-positive bacteria, oyster defensins were shown here to be specific inhibitors of a bacterial biosynthesis pathway rather than mere membrane-active agents. Indeed, at lethal concentrations, the three defensins did not compromise Staphylococcus aureus membrane integrity but inhibited the cell wall biosynthesis as indicated by the accumulation of the UDP-N-acetylmuramyl-pentapeptide cell wall precursor. In addition, a combination of antagonization assays, thin layer chromatography, and surface plasmon resonance measurements showed that oyster defensins bind almost irreversibly to the lipid II peptidoglycan precursor, thereby inhibiting the cell wall biosynthesis. To our knowledge, this is the first detailed analysis of the mechanism of action of antibacterial defensins produced by invertebrates. Interestingly, the three defensins, which were chosen as representative of the oyster defensin molecular diversity, bound differentially to lipid II. This correlated with their differential antibacterial activities. From our experimental data and the analysis of oyster defensin sequence diversity, we propose that oyster defensin activity results from selective forces that have conserved residues involved in lipid II binding and diversified residues at the surface of oyster defensins that could improve electrostatic interactions with the bacterial membranes.

  3. Bacterial vaccines and antibiotic resistance

    OpenAIRE

    Henriques-Normark, Birgitta; Normark, Staffan

    2014-01-01

    Spread of antibiotic resistance is mediated by clonal lineages of bacteria that besides being resistant also possess other properties promoting their success. Some vaccines already in use, such as the pneumococcal conjugate vaccines, have had an effect on these successful clones, but at the same time have allowed for the expansion and resistance evolution of previously minor clones not covered by the vaccine. Since resistance frequently is horizontally transferred it will be difficult to gene...

  4. Antifungal defensins and their role in plant defense.

    Science.gov (United States)

    Lacerda, Ariane F; Vasconcelos, Erico A R; Pelegrini, Patrícia Barbosa; Grossi de Sa, Maria F

    2014-01-01

    Since the beginning of the 90s lots of cationic plant, cysteine-rich antimicrobial peptides (AMP) have been studied. However, Broekaert et al. (1995) only coined the term "plant defensin," after comparison of a new class of plant antifungal peptides with known insect defensins. From there, many plant defensins have been reported and studies on this class of peptides encompass its activity toward microorganisms and molecular features of the mechanism of action against bacteria and fungi. Plant defensins also have been tested as biotechnological tools to improve crop production through fungi resistance generation in organisms genetically modified (OGM). Its low effective concentration towards fungi, ranging from 0.1 to 10 μM and its safety to mammals and birds makes them a better choice, in place of chemicals, to control fungi infection on crop fields. Herein, is a review of the history of plant defensins since their discovery at the beginning of 90s, following the advances on its structure conformation and mechanism of action towards microorganisms is reported. This review also points out some important topics, including: (i) the most studied plant defensins and their fungal targets; (ii) the molecular features of plant defensins and their relation with antifungal activity; (iii) the possibility of using plant defensin(s) genes to generate fungi resistant GM crops and biofungicides; and (iv) a brief discussion about the absence of products in the market containing plant antifungal defensins.

  5. Antifungal defensins and their role in plant defense

    Directory of Open Access Journals (Sweden)

    Ariane eLacerda

    2014-04-01

    Full Text Available Since the beginning of the 90’s lots of cationic plant, cysteine-rich antimicrobial peptides (AMP have been studied. However, Broekaert only coined the term plant defensin in 1995, after comparison of a new class of plant antifungal peptides with known insect defensins. From there, many plant defensins have been reported and studies on this class of peptides encompass its activity towards microorganisms and molecular features of the mechanism of action against bacteria and fungi. Plant defensins also have been tested as biotechnological tools to improve crop production through fungi resistance generation in organisms genetically modified (OGM. Its low effective concentration towards fungi, ranging from 0.1 to 10 µM and its safety to mammals and birds makes them a better choice, in place of chemicals, to control fungi infection on crop fields. Herein, is a review of the history of plant defensins since their discovery at the beginning of 90’s, following the advances on its structure conformation and mechanism of action towards microorganisms is reported. This review also points out some important topics, including: (i the most studied plant defensins and their fungal targets; (ii the molecular features of plant defensins and their relation with antifungal activity; (iii the possibility of using plant defensin(s genes to generate fungi resistant GM crops and biofungicides; and (iv a brief discussion about the absence of products in the market containing plant antifungal defensins.

  6. Stable integration and expression of wasabi defensin gene in "Egusi" melon (Colocynthis citrullus L.) confers resistance to Fusarium wilt and Alternaria leaf spot.

    Science.gov (United States)

    Ntui, Valentine Otang; Thirukkumaran, Gunaratnam; Azadi, Pejman; Khan, Raham Sher; Nakamura, Ikuo; Mii, Masahiro

    2010-09-01

    Production of "Egusi" melon (Colocynthis citrullus L.) in West Africa is limited by fungal diseases, such as Alternaria leaf spot and Fusarium wilt. In order to engineer "Egusi" resistant to these diseases, cotyledonary explants of two "Egusi" genotypes, 'Ejagham' and NHC1-130, were transformed with Agrobacterium tumefaciens strain EHA101 harbouring wasabi defensin gene (isolated from Wasabia japonica L.) in a binary vector pEKH1. After co-cultivation for 3 days, infected explants were transferred to MS medium containing 100 mg l(-l) kanamycin to select transformed tissues. After 3 weeks of culture, adventitious shoots appeared directly along the edges of the explants. As much as 19 out of 52 (36.5%) and 25 out of 71 (35.2%) of the explants in genotype NHC1-130 and 'Ejagham', respectively, formed shoots after 6 weeks of culture. As much as 74% (14 out of 19) of the shoots regenerated in genotype NHC1-130 and 72% (18 out of 25) of those produced in genotype 'Ejagham' were transgenic. A DNA fragment corresponding to the wasabi defensin gene or the selection marker nptII was amplified by PCR from the genomic DNA of all regenerated plant clones rooted on hormone-free MS medium under the same selection pressure, suggesting their transgenic nature. Southern blot analysis confirmed successful integration of 1-5 copies of the transgene. RT-PCR, northern and western blot analyses revealed that wasabi defensin gene was expressed in transgenic lines. Transgenic lines showed increased levels of resistance to Alternaria solani, which causes Alternaria leaf spot and Fusarium oxysporum, which causes Fusarium wilt, as compared to that of untransformed plants.

  7. Transfer and expression of the rabbit defensin NP-1 gene in lettuce (Lactuca sativa).

    Science.gov (United States)

    Song, D; Xiong, X; Tu, W F; Yao, W; Liang, H W; Chen, F J; He, Z Q

    2017-01-23

    Lettuce (Lactuca sativa L.) is an annual plant of the daisy family, Asteraceae, with high food and medicinal value. However, the crop is susceptible to several viruses that are transmitted by aphids and is highly vulnerable to post-harvest diseases, as well as insect and mammal pests and fungal and bacterial diseases. Here, the rabbit defensin gene NP-1 was transferred into lettuce by Agrobacterium-mediated transformation to obtain a broad-spectrum disease-resistant lettuce. Transgenic lettuce plants were selected and regenerated on selective media. The presence of the NP-1 gene in these plants was confirmed by western blot analyses. Resistance tests revealed native defensin NP-1 expression conferred partial resistance to Bacillus subtilis and Pseudomonas aeruginosa, which suggests new possibilities for lettuce disease resistance.

  8. Dielectrophoretic assay of bacterial resistance to antibiotics

    Energy Technology Data Exchange (ETDEWEB)

    Johari, Juliana [School of Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK (United Kingdom); Huebner, Yvonne [School of Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK (United Kingdom); Hull, Judith C [School of Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK (United Kingdom); Dale, Jeremy W [School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK (United Kingdom); Hughes, Michael P [School of Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK (United Kingdom)

    2003-07-21

    The dielectrophoretic collection spectra of antibiotic-sensitive and antibiotic-resistant strains of Staphylococcus epidermidis have been determined. These indicate that in the absence of antibiotic treatment there is a strong similarity between the dielectric properties of sensitive and resistant strains, and that there is a significant difference between the sensitive strains before and after treatment with the antibiotic streptomycin after 24 h exposure. This method offers possibilities for the assessment of bacterial resistance to antibiotics. (note)

  9. Bacterial canker resistance in tomato

    NARCIS (Netherlands)

    Sen, Y.

    2014-01-01

    Clavibacter michiganensis subsp. michiganensis (Cmm) is the pathogen causing bacterial  canker in tomato. The disease was described for the first time in 1910 in Michigan, USA. Cmmis considered the most harmful bacteria threatening tomato. Disease transmission occurs via seed and symptoms becom

  10. Bacterial canker resistance in tomato

    OpenAIRE

    Sen, Y.

    2014-01-01

    Clavibacter michiganensis subsp. michiganensis (Cmm) is the pathogen causing bacterial  canker in tomato. The disease was described for the first time in 1910 in Michigan, USA. Cmmis considered the most harmful bacteria threatening tomato. Disease transmission occurs via seed and symptoms become visible at least 20 days after infection. Due to its complex strategy and transmission, Cmm is under quarantine regulation in EU and other countries. There is no method to stop disease progress i...

  11. Whole blood defensin mRNA expression is a predictive biomarker of docetaxel response in castration-resistant prostate cancer

    Directory of Open Access Journals (Sweden)

    Kohli M

    2015-07-01

    Full Text Available Manish Kohli,1 Charles YF Young,2 Donald J Tindall,2 Debashis Nandy,1 Kyle M McKenzie,3 Graham H Bevan,4 Krishna Vanaja Donkena5 1Department of Oncology, 2Department of Urology, 3Department of Geriatric Medicine, Mayo Clinic, Rochester, MN, 4University of Rochester Medical Center, Rochester, NY, 5Center for Individualized Medicine, Mayo Clinic, Rochester, MN, USA Abstract: This study tested the potential of circulating RNA-based signals as predictive biomarkers for docetaxel response in patients with metastatic castration-resistant prostate cancer (CRPC. RNA was analyzed in blood from six CRPC patients by whole-transcriptome sequencing (total RNA-sequencing before and after docetaxel treatment using the Illumina’s HiSeq platform. Targeted RNA capture and sequencing was performed in an independent cohort of ten patients with CRPC matching the discovery cohort to confirm differential expression of the genes. Response to docetaxel was defined on the basis of prostate-specific antigen levels and imaging criteria. Two-way analysis of variance was used to compare differential gene expression in patients classified as responders versus nonresponders before and after docetaxel treatment. Thirty-four genes with two-fold differentially expressed transcripts in responders versus nonresponders were selected from total RNA-sequencing for further validation. Targeted RNA capture and sequencing showed that 13/34 genes were differentially expressed in responders. Alpha defensin genes DEFA1, DEFA1B, and DEFA3 exhibited significantly higher expression in responder patients compared with nonresponder patients before administration of chemotherapy (fold change >2.5. In addition, post-docetaxel treatment significantly increased transcript levels of these defensin genes in responders (fold change >2.8. Our results reveal that patients with higher defensin RNA transcripts in blood respond well to docetaxel therapy. We suggest that monitoring DEFA1, DEFA1B, and DEFA3

  12. Antibiotic resistance of bacterial biofilms

    DEFF Research Database (Denmark)

    Hoiby, N.; Bjarnsholt, T.; Givskov, M.

    2010-01-01

    and other components of the body's defence system. The persistence of, for example, staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is caused by biofilm-growing mucoid strains...... to antibiotics. Biofilm growth is associated with an increased level of mutations as well as with quorum-sensing-regulated mechanisms. Conventional resistance mechanisms such as chromosomal beta-lactamase, upregulated efflux pumps and mutations in antibiotic target molecules in bacteria also contribute...

  13. Enteric alpha defensins in norm and pathology

    Directory of Open Access Journals (Sweden)

    Lisitsyn Nikolai A

    2012-01-01

    Full Text Available Abstract Microbes living in the mammalian gut exist in constant contact with immunity system that prevents infection and maintains homeostasis. Enteric alpha defensins play an important role in regulation of bacterial colonization of the gut, as well as in activation of pro- and anti-inflammatory responses of the adaptive immune system cells in lamina propria. This review summarizes currently available data on functions of mammalian enteric alpha defensins in the immune defense and changes in their secretion in intestinal inflammatory diseases and cancer.

  14. Defensins: natural component of human innate immunity.

    Science.gov (United States)

    Jarczak, Justyna; Kościuczuk, Ewa M; Lisowski, Paweł; Strzałkowska, Nina; Jóźwik, Artur; Horbańczuk, Jarosław; Krzyżewski, Józef; Zwierzchowski, Lech; Bagnicka, Emilia

    2013-09-01

    The widespread use of antibiotics has contributed to a huge increase in the number of resistant bacteria. New classes of drugs are therefore being developed of which defensins are a potential source. Defensins are a group of antimicrobial peptides found in different living organisms, involved in the first line of defense in their innate immune response against pathogens. This review summarizes the results of studies of this family of human antimicrobial peptides (AMPs). There is a special emphasis on describing the entire group and individual peptides, history of their discovery, their functions and expression sites. The results of the recent studies on the use of the biologically active peptides in human medicine are also presented. The pharmaceutical potential of human defensins cannot be ignored, especially considering their strong antimicrobial activity and properties such as low molecular weight, reduced immunogenicity, broad activity spectrum and resistance to proteolysis, but there are still many challenges and questions regarding the possibilities of their practical application.

  15. Persistence of antibiotic resistance in bacterial populations.

    Science.gov (United States)

    Andersson, Dan I; Hughes, Diarmaid

    2011-09-01

    Unfortunately for mankind, it is very likely that the antibiotic resistance problem we have generated during the last 60 years due to the extensive use and misuse of antibiotics is here to stay for the foreseeable future. This view is based on theoretical arguments, mathematical modeling, experiments and clinical interventions, suggesting that even if we could reduce antibiotic use, resistant clones would remain persistent and only slowly (if at all) be outcompeted by their susceptible relatives. In this review, we discuss the multitude of mechanisms and processes that are involved in causing the persistence of chromosomal and plasmid-borne resistance determinants and how we might use them to our advantage to increase the likelihood of reversing the problem. Of particular interest is the recent demonstration that a very low antibiotic concentration can be enriching for resistant bacteria and the implication that antibiotic release into the environment could contribute to the selection for resistance. Several mechanisms are contributing to the stability of antibiotic resistance in bacterial populations and even if antibiotic use is reduced it is likely that most resistance mechanisms will persist for considerable times.

  16. Bacterial Enzymes and Antibiotic Resistance- Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-25

    By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β-lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes.

  17. Mechanisms of bacterial resistance to chromium compounds.

    Science.gov (United States)

    Ramírez-Díaz, Martha I; Díaz-Pérez, César; Vargas, Eréndira; Riveros-Rosas, Héctor; Campos-García, Jesús; Cervantes, Carlos

    2008-06-01

    Chromium is a non-essential and well-known toxic metal for microorganisms and plants. The widespread industrial use of this heavy metal has caused it to be considered as a serious environmental pollutant. Chromium exists in nature as two main species, the trivalent form, Cr(III), which is relatively innocuous, and the hexavalent form, Cr(VI), considered a more toxic species. At the intracellular level, however, Cr(III) seems to be responsible for most toxic effects of chromium. Cr(VI) is usually present as the oxyanion chromate. Inhibition of sulfate membrane transport and oxidative damage to biomolecules are associated with the toxic effects of chromate in bacteria. Several bacterial mechanisms of resistance to chromate have been reported. The best characterized mechanisms comprise efflux of chromate ions from the cell cytoplasm and reduction of Cr(VI) to Cr(III). Chromate efflux by the ChrA transporter has been established in Pseudomonas aeruginosa and Cupriavidus metallidurans (formerly Alcaligenes eutrophus) and consists of an energy-dependent process driven by the membrane potential. The CHR protein family, which includes putative ChrA orthologs, currently contains about 135 sequences from all three domains of life. Chromate reduction is carried out by chromate reductases from diverse bacterial species generating Cr(III) that may be detoxified by other mechanisms. Most characterized enzymes belong to the widespread NAD(P)H-dependent flavoprotein family of reductases. Several examples of bacterial systems protecting from the oxidative stress caused by chromate have been described. Other mechanisms of bacterial resistance to chromate involve the expression of components of the machinery for repair of DNA damage, and systems related to the homeostasis of iron and sulfur.

  18. Novel anti-bacterial activities of β-defensin 1 in human platelets: suppression of pathogen growth and signaling of neutrophil extracellular trap formation.

    Directory of Open Access Journals (Sweden)

    Bjoern F Kraemer

    2011-11-01

    Full Text Available Human β-defensins (hBD are antimicrobial peptides that curb microbial activity. Although hBD's are primarily expressed by epithelial cells, we show that human platelets express hBD-1 that has both predicted and novel antibacterial activities. We observed that activated platelets surround Staphylococcus aureus (S. aureus, forcing the pathogens into clusters that have a reduced growth rate compared to S. aureus alone. Given the microbicidal activity of β-defensins, we determined whether hBD family members were present in platelets and found mRNA and protein for hBD-1. We also established that hBD-1 protein resided in extragranular cytoplasmic compartments of platelets. Consistent with this localization pattern, agonists that elicit granular secretion by platelets did not readily induce hBD-1 release. Nevertheless, platelets released hBD-1 when they were stimulated by α-toxin, a S. aureus product that permeabilizes target cells. Platelet-derived hBD-1 significantly impaired the growth of clinical strains of S. aureus. hBD-1 also induced robust neutrophil extracellular trap (NET formation by target polymorphonuclear leukocytes (PMNs, which is a novel antimicrobial function of β-defensins that was not previously identified. Taken together, these data demonstrate that hBD-1 is a previously-unrecognized component of platelets that displays classic antimicrobial activity and, in addition, signals PMNs to extrude DNA lattices that capture and kill bacteria.

  19. Interaction of Defensins with Model Cell Membranes

    Science.gov (United States)

    Sanders, Lori K.; Schmidt, Nathan W.; Yang, Lihua; Mishra, Abhijit; Gordon, Vernita D.; Selsted, Michael E.; Wong, Gerard C. L.

    2009-03-01

    Antimicrobial peptides (AMPs) comprise a key component of innate immunity for a wide range of multicellular organisms. For many AMPs, activity comes from their ability to selectively disrupt and lyse bacterial cell membranes. There are a number of proposed models for this action, but the detailed molecular mechanism of selective membrane permeation remains unclear. Theta defensins are circularized peptides with a high degree of selectivity. We investigate the interaction of model bacterial and eukaryotic cell membranes with theta defensins RTD-1, BTD-7, and compare them to protegrin PG-1, a prototypical AMP, using synchrotron small angle x-ray scattering (SAXS). The relationship between membrane composition and peptide induced changes in membrane curvature and topology is examined. By comparing the membrane phase behavior induced by these different peptides we will discuss the importance of amino acid composition and placement on membrane rearrangement.

  20. Engineering antibiotic production and overcoming bacterial resistance.

    Science.gov (United States)

    Planson, Anne-Gaëlle; Carbonell, Pablo; Grigoras, Ioana; Faulon, Jean-Loup

    2011-07-01

    Progress in DNA technology, analytical methods and computational tools is leading to new developments in synthetic biology and metabolic engineering, enabling new ways to produce molecules of industrial and therapeutic interest. Here, we review recent progress in both antibiotic production and strategies to counteract bacterial resistance to antibiotics. Advances in sequencing and cloning are increasingly enabling the characterization of antibiotic biosynthesis pathways, and new systematic methods for de novo biosynthetic pathway prediction are allowing the exploration of the metabolic chemical space beyond metabolic engineering. Moreover, we survey the computer-assisted design of modular assembly lines in polyketide synthases and non-ribosomal peptide synthases for the development of tailor-made antibiotics. Nowadays, production of novel antibiotic can be tranferred into any chosen chassis by optimizing a host factory through specific strain modifications. These advances in metabolic engineering and synthetic biology are leading to novel strategies for engineering antimicrobial agents with desired specificities.

  1. Thermodynamic instability of viral proteins is a pathogen-associated molecular pattern targeted by human defensins.

    Science.gov (United States)

    Kudryashova, Elena; Koneru, Pratibha C; Kvaratskhelia, Mamuka; Strömstedt, Adam A; Lu, Wuyuan; Kudryashov, Dmitri S

    2016-09-01

    Human defensins are innate immune defense peptides with a remarkably broad repertoire of anti-pathogen activities. In addition to modulating immune response, inflammation, and angiogenesis, disintegrating bacterial membranes, and inactivating bacterial toxins, defensins are known to intercept various viruses at different stages of their life cycles, while remaining relatively benign towards human cells and proteins. Recently we have found that human defensins inactivate proteinaceous bacterial toxins by taking advantage of their low thermodynamic stability and acting as natural "anti-chaperones", i.e. destabilizing the native conformation of the toxins. In the present study we tested various proteins produced by several viruses (HIV-1, PFV, and TEV) and found them to be susceptible to destabilizing effects of human α-defensins HNP-1 and HD-5 and the synthetic θ-defensin RC-101, but not β-defensins hBD-1 and hBD-2 or structurally related plant-derived peptides. Defensin-induced unfolding promoted exposure of hydrophobic groups otherwise confined to the core of the viral proteins. This resulted in precipitation, an enhanced susceptibility to proteolytic cleavage, and a loss of viral protein activities. We propose, that defensins recognize and target a common and essential physico-chemical property shared by many bacterial toxins and viral proteins - the intrinsically low thermodynamic protein stability.

  2. Resistencia bacteriana Bacterial resistance to antimicrobial agents

    Directory of Open Access Journals (Sweden)

    Jesualdo Fuentes

    1993-01-01

    Full Text Available

    Se presenta un panorama de la resistencia bacteriana incluyendo su fisiopatogenia y formas de presentación y se establecen algunas consideraciones generales de tipo clínico como auxiliares para racionalizar el uso de los antimicrobianos y evitar o retardar el problema de la resistencia; éste plantea la necesidad de un reordenamiento definitivo en la prescripción de antimicrobianos. No será tanto la creación o descubrimiento de nuevos antibióticos sino la racionalización del manejo de los existentes lo que permitirá alcanzar victorias sobre estos microorganismos. Es Importante mantener educación continua sobre el uso adecuado de los antimicrobianos desde los puntos de vista epidemiológico, farmacocinético y fisiopatogénico.

    An overview on bacterial resistance to antimicrobial agents is presented. It includes the different genetic mechanisms for Its development and the biochemical phenomena that explain It. Some clinical considerations are proposed in order to rationalize the use of these drugs and to avoid or delay the appearance of resistance.

  3. Bacterial and archaeal resistance to ionizing radiation

    Science.gov (United States)

    Confalonieri, F.; Sommer, S.

    2011-01-01

    Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

  4. Bacterial Gibberellins Induce Systemic Resistance of Plants

    Directory of Open Access Journals (Sweden)

    I. N. FEKLISTOVA

    2014-06-01

    Full Text Available It is generally agreed today that some rhizosphere bacteria can ensure induced systemic resistance to pathogens. In this paper we tested the ability of gibberellins produced by rhizosphere non-pathogenic bacteria Pseudomonas aurantiaca to induce systemic resistance to alternariosis agent – Alternaria brassicicola – in oilseed rape plants.Oilseed rape (Brássica nápus is one of the most promising oil-bearing croppers. It allows improving the supply of population with vegetable oil, animal and poultry industries with high quality vegetable protein. It is used for biofuel production as well.Gibberellin preparation was isolated from liquid culture of strain Pseudomonas aurantiaca grown in 250 mL of M9 medium (48 h, 28 °C under darkroom conditions. Gibberellins were extracted according procedure described by Tien et al. (1979. Gibberellins concentration in the medium was determined by fluorometric method.Elicitor activity of bacterial metabolites – gibberellins – was analyzed in model system of artificial inoculation of oilseed rape germs with phytopathogenic fungi Alternaria brassicicola. The elicitor action efficiency was evaluated on the 15th day of oilseed rape cultivation based on the percentage of leaf surface covered by necrotic lesions.Gibberellins were shown to induce systemic resistance resulted in decreasing of oil seed plants   vulnerability by 52.7%.It is known that under the unfavorable conditions plants synthesis the reactive oxygen intermediates   which activate destructive processes. One of the first organism reactions to stress action is the change of the lipid peroxidation level. It was shown that treatment of the soil with gibberellins resulted in decreasing of the lipid peroxidation level twofold.Gibberellins were shown to have a similar effect on permeability of cell membranes for free nucleotides. The permeability of cell membranes in leaves decreased 2.8-fold at room temperature. We suggest that gibberellins

  5. Both group 4 capsule and lipopolysaccharide O-antigen contribute to enteropathogenic Escherichia coli resistance to human α-defensin 5.

    Directory of Open Access Journals (Sweden)

    Jenny-Lee Thomassin

    Full Text Available Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC are food-borne pathogens that colonize the small intestine and colon, respectively. To cause disease, these pathogens must overcome the action of different host antimicrobial peptides (AMPs secreted into these distinct niches. We have shown previously that EHEC expresses high levels of the OmpT protease to inactivate the human cathelicidin LL-37, an AMP present in the colon. In this study, we investigate the mechanisms used by EPEC to resist human α-defensin 5 (HD-5, the most abundant AMP in the small intestine. Quantitative PCR was used to measure transcript levels of various EPEC surface structures. High transcript levels of gfcA, a gene required for group 4 capsule (G4C production, were observed in EPEC, but not in EHEC. The unencapsulated EPEC ∆gfcA and EHEC wild-type strains were more susceptible to HD-5 than EPEC wild-type. Since the G4C is composed of the same sugar repeats as the lipopolysaccharide O-antigen, an -antigen ligase (waaL deletion mutant was generated in EPEC to assess its role in HD-5 resistance. The ∆waaL EPEC strain was more susceptible to HD-5 than both the wild-type and ∆gfcA strains. The ∆gfcA∆waaL EPEC strain was not significantly more susceptible to HD-5 than the ∆waaL strain, suggesting that the absence of -antigen influences G4C formation. To determine whether the G4C and -antigen interact with HD-5, total polysaccharide was purified from wild-type EPEC and added to the ∆gfcA∆waaL strain in the presence of HD-5. The addition of exogenous polysaccharide protected the susceptible strain against HD-5 killing in a dose-dependent manner, suggesting that HD-5 binds to the polysaccharides present on the surface of EPEC. Altogether, these findings indicate that EPEC relies on both the G4C and the -antigen to resist the bactericidal activity of HD-5.

  6. Intravenous antibiotics infusion and bacterial resistence: nursing responsability

    OpenAIRE

    2006-01-01

    The success of antibiotics treatment and development of bacterial resistance depend on many factors. The preparation and management of these factors are associated with nursing care. The aim of this paper is review literature about preparation, management and knowledge of intravenous antibiotics errors analyzing possibilities of influence of bacterial resistance prevention by nurses. Methods: a systematic review was done from LiILACS and M...

  7. Persistence and resistance as complementary bacterial adaptations to antibiotics

    OpenAIRE

    Vogwill, T.; Comfort, A. C.; Furió, V.; MacLean, R. C.

    2016-01-01

    Abstract Bacterial persistence represents a simple of phenotypic heterogeneity, whereby a proportion of cells in an isogenic bacterial population can survive exposure to lethal stresses such as antibiotics. In contrast, genetically based antibiotic resistance allows for continued growth in the presence of antibiotics. It is unclear, however, whether resistance and persistence are complementary or alternative evolutionary adaptations to antibiotics. Here, we investigate the co‐evolution of res...

  8. Ribosome-targeting antibiotics and mechanisms of bacterial resistance.

    Science.gov (United States)

    Wilson, Daniel N

    2014-01-01

    The ribosome is one of the main antibiotic targets in the bacterial cell. Crystal structures of naturally produced antibiotics and their semi-synthetic derivatives bound to ribosomal particles have provided unparalleled insight into their mechanisms of action, and they are also facilitating the design of more effective antibiotics for targeting multidrug-resistant bacteria. In this Review, I discuss the recent structural insights into the mechanism of action of ribosome-targeting antibiotics and the molecular mechanisms of bacterial resistance, in addition to the approaches that are being pursued for the production of improved drugs that inhibit bacterial protein synthesis.

  9. Uropathogenic Escherichia coli (UPEC) induced antimicrobial gene expression in the male reproductive tract of rat: evaluation of the potential of Defensin 21 to limit infection.

    Science.gov (United States)

    Biswas, B; Bhushan, S; Rajesh, A; Suraj, S K; Lu, Y; Meinhardt, A; Yenugu, S

    2015-03-01

    Escherichia coli (E. coli) is a common pathogen in epididymitis, which represents a prevalent entity in male reproductive tract infections (RTI). Although current treatment regimens using antibiotics are satisfactory, development of antimicrobial resistance by the pathogen represents a challenge in the management of RTI. Hence, identification of antimicrobial peptides as alternatives to antibiotics has gained importance. We demonstrate that in a rat epididymo-orchitis model induced with uropathogenic E. coli (UPEC) strain MTCC 729, the expression of defensins and defensin-like Spag11 genes are induced in the epididymis and testes. The induction of antimicrobial gene expression is paralleled by phosphorylation of the NF-kB subunit p65 and the inhibitor of NFkB (IkB-alpha), decreased levels of histone deacetylase 1 and increased methylation of Histone 3, indicating the role of classical Toll-like receptor mediated signaling and epigenetic regulation. Recombinant Defensin 21, when administered to UPEC-infected rats, substantially reduced the bacterial load in the epididymis and testis and proved to be more effective than gentamycin. The ability of Defensin 21 to limit RTI provides support that antibacterial proteins of the male reproductive tract may be used as potential alternatives to antibiotics in treatment of this disease.

  10. New source of bacterial soft rot resistance in potato tubers

    Science.gov (United States)

    Bacterial soft rot caused by Pectobacterium and Dickeya species can cause major losses to the potato (Solanum tuberosum L.) industry, mostly due to tuber rot in storage. There are few germplasm resources for soft rot resistance breeding. Here, we introduce a resistant diploid wild potato relative, M...

  11. BLOOD CONTENTS OF DEFENSINS IN PATIENTS WITH PNEUMONIAS CAUSED BY INFLUENZA А/H1N1

    Directory of Open Access Journals (Sweden)

    E. N. Romanova

    2012-01-01

    Full Text Available Abstract. Defensin amounts in severe forms of influenza-associated pneumonia and acute respiratory distresssyndrome is increased to a lesser degree than in pneumonias with milder clinical course. This difference may be determined by selective accumulation of defensins in areas of infectious lesions. Mean content of α-defensins in non-severe pneumonias with influenza А/H1N1 accompanied by normocytosis or leukopenia, is higher than in bacterial pneumonias with leukocytosis. High levels of defensins, along with substantially increased neutrophil counts, associated with normocytosis or leukopenia, reflect a pronounced systemic inflammatory response caused by influenza А/H1N1.

  12. Selection of bacterial wilt-resistant tomato through tissue culture.

    Science.gov (United States)

    Toyoda, H; Shimizu, K; Chatani, K; Kita, N; Matsuda, Y; Ouchi, S

    1989-06-01

    Bacterial wilt-resistant plants were obtained using a tomato tissue culture system. A virulent strain ofPseudomonas solanacearum secreted some toxic substances into the culture medium. Leaf explant-derived callus tissues which were resistant to these toxic substances in the culture filtrate were selectedin vitro and regenerated into plants. These plants expressed bacterial wilt resistance at the early infection stage to suppress or delay the growth of the inoculated bacteria. On the other hand, complete resistance was obtained in self-pollinated progeny of regenerants derived from non-selected callus tissues. These plants showed a high resistance when inoculated with this strain, and were also resistant when planted in a field infested with a different strain of the pathogen.

  13. Multiple drug resistance and bacterial infection

    Institute of Scientific and Technical Information of China (English)

    Asad U Khan

    2008-01-01

    Drug resistance is becoming a great problem in developing countries due to excessive use and misuse of antibi-otics.The emergence of new pathogenic strains with resistance developed against most of the antibiotics which may cause,difficult to treat infection.To understand the current scenario in different mode of infection is most important for the clinicians and medical practitioners.This article summarized some common infections and an-tibiotic resistance pattern found among these pathogens.

  14. Antibiotics & Resistance : bacterial multidrug resistance and photoactivatable antibiotics

    NARCIS (Netherlands)

    van der Berg, Jan Pieter

    2014-01-01

    Antibioticaresistentie in bacteriën is een serieus gevaar voor de gezondheidszorg. Bacteriën kunnen op verscheidene manieren de schadelijke effecten van antibiotica omzeilen en een van deze manieren is door de medicijnen uit de cel te pompen. Dit onderzoek bestudeerde de rol van zulke transporteiwit

  15. Construction of a Mammary-specific Expression Vector of Humanα-defensin-1 (HNP-1) Gene

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1 IntroductionDefensins, also called human neutrophil peptides(HNP), are small cationic peptides with broad antimicrobial activity~([1]). Human defensins are highly abundant in the cytoplasmic granules of polymorphonuclear neutrophils. Alpha-defensin-1 is an important mediator in either innate immunity or anti-infection. It can be developed to be an ideal new type antibiotic and may provide a better solution for the present situation of extensive antibiotics-resistence. It is difficult to achieve amount of ...

  16. Intravenous antibiotics infusion and bacterial resistence: nursing responsability

    Directory of Open Access Journals (Sweden)

    Heloisa Helena Karnas Hoefel

    2006-12-01

    Full Text Available The success of antibiotics treatment and development of bacterial resistance depend on many factors. The preparation and management of these factors are associated with nursing care. The aim of this paper is review literature about preparation, management and knowledge of intravenous antibiotics errors analyzing possibilities of influence of bacterial resistance prevention by nurses. Methods: a systematic review was done from LiILACS and Medline searching for the word nursing and bacterial resistance, antibiotics control, hospital infections, administration drugs, errors and adverse events. There were chose 58 papers about nursing and/or were basics for international and Brazilian studies. Results: It was described international classifications errors and consequences analyzing their possible influences on antibiotics effects. Based on these knowledge, interventions are recommended to implement safety practice and care.

  17. Prevalence and antimicrobial resistance pattern of bacterial meningitis in Egypt

    Directory of Open Access Journals (Sweden)

    Shaban Lamyaa

    2009-09-01

    Full Text Available Abstract Infectious diseases are the leading cause of morbidity and mortality in the developing world. In Egypt bacterial diseases constitute a great burden, with several particular bacteria sustaining the leading role of multiple serious infections. This article addresses profound bacterial agents causing a wide array of infections including but not limited to pneumonia and meningitis. The epidemiology of such infectious diseases and the prevalence of Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae are reviewed in the context of bacterial meningitis. We address prevalent serotypes in Egypt, antimicrobial resistance patterns and efficacy of vaccines to emphasize the importance of periodic surveillance for appropriate preventive and treatment strategies.

  18. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants

    Science.gov (United States)

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-01-01

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics. PMID:27681908

  19. Nonlinear Stochastic Modelling of Antimicrobial resistance in Bacterial Populations

    DEFF Research Database (Denmark)

    Philipsen, Kirsten Riber

    in humans and animals. To prevent the evolution and spread of resistance, there is a need for further understanding of its dynamics. A grey-box modelling approach based on stochastic differential equations is the main and innovative method applied to study bacterial systems in this thesis. Through...... for bacterial growth in an environment with multiple substrates. Models based on stochastic differential equations are also used in studies of mutation and conjugation. Mutation and conjugation are important mechanisms for the development of resistance. Earlier models for conjugation have described systems...

  20. Proteome studies of bacterial antibiotic resistance mechanisms.

    Science.gov (United States)

    Vranakis, Iosif; Goniotakis, Ioannis; Psaroulaki, Anna; Sandalakis, Vassilios; Tselentis, Yannis; Gevaert, Kris; Tsiotis, Georgios

    2014-01-31

    Ever since antibiotics were used to help humanity battle infectious diseases, microorganisms straight away fought back. Antibiotic resistance mechanisms indeed provide microbes with possibilities to by-pass and survive the action of antibiotic drugs. Several methods have been employed to identify these microbial resistance mechanisms in an ongoing effort to reduce the steadily increasing number of treatment failures due to multi-drug-resistant microbes. Proteomics has evolved to an important tool for this area of research. Following rapid advances in whole genome sequencing, proteomic technologies have been widely used to investigate microbial gene expression. This review highlights the contribution of proteomics in identifying microbial drug resistance mechanisms. It summarizes different proteomic studies on bacteria resistant to different antibiotic drugs. The review further includes an overview of the methodologies used, as well as lists key proteins identified, thus providing the reader not only a summary of research already done, but also directions for future research. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.

  1. Mechanisms and consequences of bacterial resistance to antimicrobial peptides.

    Science.gov (United States)

    Andersson, D I; Hughes, D; Kubicek-Sutherland, J Z

    2016-05-01

    Cationic antimicrobial peptides (AMPs) are an intrinsic part of the human innate immune system. Over 100 different human AMPs are known to exhibit broad-spectrum antibacterial activity. Because of the increased frequency of resistance to conventional antibiotics there is an interest in developing AMPs as an alternative antibacterial therapy. Several cationic peptides that are derivatives of AMPs from the human innate immune system are currently in clinical development. There are also ongoing clinical studies aimed at modulating the expression of AMPs to boost the human innate immune response. In this review we discuss the potential problems associated with these therapeutic approaches. There is considerable experimental data describing mechanisms by which bacteria can develop resistance to AMPs. As for any type of drug resistance, the rate by which AMP resistance would emerge and spread in a population of bacteria in a natural setting will be determined by a complex interplay of several different factors, including the mutation supply rate, the fitness of the resistant mutant at different AMP concentrations, and the strength of the selective pressure. Several studies have already shown that AMP-resistant bacterial mutants display broad cross-resistance to a variety of AMPs with different structures and modes of action. Therefore, routine clinical administration of AMPs to treat bacterial infections may select for resistant bacterial pathogens capable of better evading the innate immune system. The ramifications of therapeutic levels of exposure on the development of AMP resistance and bacterial pathogenesis are not yet understood. This is something that needs to be carefully studied and monitored if AMPs are used in clinical settings.

  2. Alternatives to overcoming bacterial resistances: State-of-the-art.

    Science.gov (United States)

    Rios, Alessandra C; Moutinho, Carla G; Pinto, Flávio C; Del Fiol, Fernando S; Jozala, Angela; Chaud, Marco V; Vila, Marta M D C; Teixeira, José A; Balcão, Victor M

    2016-10-01

    Worldwide, bacterial resistance to chemical antibiotics has reached such a high level that endangers public health. Presently, the adoption of alternative strategies that promote the elimination of resistant microbial strains from the environment is of utmost importance. This review discusses and analyses several (potential) alternative strategies to current chemical antibiotics. Bacteriophage (or phage) therapy, although not new, makes use of strictly lytic phage particles as an alternative, or a complement, in the antimicrobial treatment of bacterial infections. It is being rediscovered as a safe method, because these biological entities devoid of any metabolic machinery do not possess any affinity whatsoever to eukaryotic cells. Lysin therapy is also recognized as an innovative antimicrobial therapeutic option, since the topical administration of preparations containing purified recombinant lysins with amounts in the order of nanograms, in infections caused by Gram-positive bacteria, demonstrated a high therapeutic potential by causing immediate lysis of the target bacterial cells. Additionally, this therapy exhibits the potential to act synergistically when combined with certain chemical antibiotics already available on the market. Another potential alternative antimicrobial therapy is based on the use of antimicrobial peptides (AMPs), amphiphilic polypeptides that cause disruption of the bacterial membrane and can be used in the treatment of bacterial, fungal and viral infections, in the prevention of biofilm formation, and as antitumoral agents. Interestingly, bacteriocins are a common strategy of bacterial defense against other bacterial agents, eliminating the potential opponents of the former and increasing the number of available nutrients in the environment for their own growth. They can be applied in the food industry as biopreservatives and as probiotics, and also in fighting multi-resistant bacterial strains. The use of antibacterial antibodies

  3. Defensins from insects and plants interact with fungal glucosylceramides

    NARCIS (Netherlands)

    Thevissen, K.; Warnecke, D.C.; François, I.E.J.A.; Leipelt, M.; Heinz, E.; Ott, C.; Zähringer, U.; Thomma, B.P.H.J.; Ferket, K.K.A.; Cammue, B.P.A.

    2004-01-01

    Growth of the yeast species Candida albicans and Pichia pastoris is inhibited by RsAFP2, a plant defensin isolated from radish seed (Raphanus sativus), at micromolar concentrations. In contrast, gcs-deletion mutants of both yeast species are resistant toward RsAFP2. GCS genes encode UDP-glucose:cera

  4. Resistance to antibiotics targeted to the bacterial cell wall.

    Science.gov (United States)

    Nikolaidis, I; Favini-Stabile, S; Dessen, A

    2014-03-01

    Peptidoglycan is the main component of the bacterial cell wall. It is a complex, three-dimensional mesh that surrounds the entire cell and is composed of strands of alternating glycan units crosslinked by short peptides. Its biosynthetic machinery has been, for the past five decades, a preferred target for the discovery of antibacterials. Synthesis of the peptidoglycan occurs sequentially within three cellular compartments (cytoplasm, membrane, and periplasm), and inhibitors of proteins that catalyze each stage have been identified, although not all are applicable for clinical use. A number of these antimicrobials, however, have been rendered inactive by resistance mechanisms. The employment of structural biology techniques has been instrumental in the understanding of such processes, as well as the development of strategies to overcome them. This review provides an overview of resistance mechanisms developed toward antibiotics that target bacterial cell wall precursors and its biosynthetic machinery. Strategies toward the development of novel inhibitors that could overcome resistance are also discussed.

  5. [Effect of Three Typical Disinfection Byproducts on Bacterial Antibiotic Resistance].

    Science.gov (United States)

    Lü, Lu; Zhang, Meng-lu; Wang, Chun-ming; Lin, Hui-rong; Yu, Xin

    2015-07-01

    The effect of typical disinfection byproducts (DBPs) on bacterial antibiotic resistance was investigated in this study. chlorodibromomethane (CDBM), iodoacetic acid (IAA) and chloral hydrate (CH) were selected, which belong to trihalomethanes (THMs), haloacetic acids (HAAs) and aldehydes, respectively. After exposure to the selected DBPs, the resistance change of the tested strains to antibiotics was determined. As a result, all of the three DBPs induced Pseudomonas aeruginosa PAO1 to gain increased resistance to the five antibiotics tested, and the DBPs ranked as IAA > CH > CDBM according to their enhancement effects. Multidrug resistance could also be enhanced by treatment with IAA. The same result was observed in Escherichia coli K12, suggesting that the effect of DBPs on antibiotic resistance was a common phenomenon. The mechanism was probably that DBPs stimulated oxidative stress, which induced mutagenesis. And the antibiotic resistance mutation frequency could be increased along with mutagenesis. This study revealed that the acquisition of bacterial antibiotic resistance might be related to DBPs in drinking water systems. Besides the genotoxicological risks, the epidemiological risks of DBPs should not be overlooked.

  6. Bacterial resistance to Quaternary Ammonium Compounds (QAC) disinfectants.

    Science.gov (United States)

    Bragg, Robert; Jansen, Arina; Coetzee, Marisa; van der Westhuizen, Wouter; Boucher, Charlotte

    2014-01-01

    Control of bacterial diseases has, for many years, been dependent on the use of antibiotics. Due to the high levels of efficacy of antibiotics in the past other disease control options have, to a large extent, been neglected. Mankind is now facing an increasing problem with antibiotic resistance. In an effort to retain some antibiotics for human use, there are moves afoot to limit or even ban the use of antibiotics in animal production. The use of antibiotics as growth promoters have been banned in the European Union and the USA. The potential ban on the use of antibiotics to treat diseases in production animals creates a dilemma for man-suffer significant problem with bacterial infection or suffer from a severe shortage of food! There are other options for the control of bacterial diseases. These include vaccine development, bacteriophage therapy, and improved biosecurity. Vaccine development against bacterial pathogens, particularly opportunistic pathogens, is often very challenging, as in many cases the molecular basis of the virulence is not always clearly understood. This is particularly true for Escherichia coli. Biosecurity (disinfection) has been a highly neglected area in disease control. With the ever-increasing problems with antibiotic resistance-the focus should return to improvements in biosecurity. As with antibiotics, bacteria also have mechanisms for resistance to disinfectants. To ensure that we do not replace one set of problems (increasing antibiotic resistance) with another (increasing resistance to disinfectants) we need to fully understand the modes of action of disinfectants and how the bacteria develop resistance to these disinfectants. Molecular studies have been undertaken to relate the presence of QAC resistance genes in bacteria to their levels of sensitivity to different generations of QAC-based products. The mode of action of QAC on bacteria has been studied using NanoSAM technology, where it was revealed that the QAC causes disruption

  7. Major QTL Conferring Resistance to Rice Bacterial Leaf Streak

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Bacterial leaf streak (BLS) is one of the important limiting factors to rice production in southern China and other tropical and sub-tropical areas in Asia. Resistance to BLS was found to be a quantitative trait and no major resistant gene was located in rice until date. In the present study, a new major quantitative trait locus (QTL) conferring resistance to BLS was identified from a highly resistant variety Dular by the employment of Dular/Balilla (DB) and Dular/IR24 (DI) segregation populations and was designated qBLSR-11-1. This QTL was located between the simple sequence repeat (SSR) markers RM120 and RM441 on chromosome 11 and could account for 18.1-21.7% and 36.3% of the variance in DB and DI populations, respectively. The genetic pattern of rice resistance to BLS was discussed.

  8. Population Dynamics of Patients with Bacterial Resistance in Hospital Environment

    Directory of Open Access Journals (Sweden)

    Leilei Qu

    2016-01-01

    Full Text Available During the past decades, the increase of antibiotic resistance has become a major concern worldwide. The researchers found that superbugs with new type of resistance genes (NDM-1 have two aspects of transmission characteristics; the first is that the antibiotic resistance genes can horizontally transfer among bacteria, and the other is that the superbugs can spread between humans through direct contact. Based on these two transmission mechanisms, we study the dynamics of population in hospital environment where superbugs exist. In this paper, we build three mathematic models to illustrate the dynamics of patients with bacterial resistance in hospital environment. The models are analyzed using stability theory of differential equations. Positive equilibrium points of the system are investigated and their stability analysis is carried out. Moreover, the numerical simulation of the proposed model is also performed which supports the theoretical findings.

  9. Heat-resistant bacterial phytase in broiler pelleted diets

    Directory of Open Access Journals (Sweden)

    TC de F Carlos

    2015-03-01

    Full Text Available The objective of the study was to evaluate the effects of a heat-resistant bacterial phytase added to pelleted diets on mineral digestibility, live performance, carcass traits, and bone quality of broilers. Three treatments were evaluated: Positive control; negative control, with 0.10 points reduction in calcium level and 0.15 points reduction in available phosphorus level; and negative control + phytase at 500 FTU/kg. Mineral digestibility and bone quality results demonstrated that the evaluated phytase resisted pelleting as it increased the utilization of the minerals present in the diet.

  10. Resistance of Antimicrobial Peptide Gene Transgenic Rice to Bacterial Blight

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; WU Chao; LIU Mei; LIU Xu-ri; Hu Guo-cheng; SI Hua-min; SUN Zong-xiu; LIU Wen-zhen; Fu Ya-ping

    2011-01-01

    Antimierobial peptide is a polypeptide with antimicrobial activity.Antimicrobial peptide genes Np3 and Np5 from Chinese shrimp (Fenneropenaeus Chinensis) were integrated into Oryza sativa L.subsp.japonica cv.Aichi ashahi by Agrobacterium mediated transformation system.PCR analysis showed that the positive ratios of Np3 and Np5 were 36% and 45% in T0 generation,respectively.RT-PCR analysis showed that the antimicrobial peptide genes were expressed in T1 generation,and there was no obvious difference in agronomic traits between transgenic plants and non-transgenic plants.Four Np3 and Np5 transgenic lines in T1 generation were inoculated with ×anthomonas oryzae pv.oryzae strain CR4,and all the four transgenic lines had significantly enhanced resistance to bacterial blight caused by the strain CR4.The Np5 transgenic lines also showed higher resistance to bacterial blight caused by strains JS97-2,Zhe 173 and OS-225.It is suggested that transgenic lines with Np5 gene might possess broad spectrum resistance to rice bacterial blight.

  11. Bacterial Resistance%细菌的耐药性

    Institute of Scientific and Technical Information of China (English)

    张丽芳

    2011-01-01

    Antibiotics play an effective role in treating various bacterial infections and ensuring the human health.But with the widespread uses of antibiotics,bacterial resistance is becoming a serious problem.Bacterial resistances are from biogenic resistance gen%抗菌药物有效治疗了各种细菌感染,保障了人类的健康。但伴生的细菌耐药性问题也逐渐显现。细菌耐药源于自然界耐药基因的存在及传递和抗生素滥用对此情况的促进作用。严谨合理地应用抗菌药物以最大限度地减少细菌耐药性发生、延长抗菌药物的疗效周期,是人类所面临的长期挑战。

  12. α-Defensins in human innate immunity.

    Science.gov (United States)

    Lehrer, Robert I; Lu, Wuyuan

    2012-01-01

    Defensins are small, multifunctional cationic peptides. They typically contain six conserved cysteines whose three intramolecular disulfides stabilize a largely β-sheet structure. This review of human α-defensins begins by describing their evolution, including their likely relationship to the Big Defensins of invertebrates, and their kinship to the β-defensin peptides of many if not all vertebrates, and the θ-defensins found in certain non-human primates. We provide a short history of the search for leukocyte-derived microbicidal molecules, emphasizing the roles played by luck (good), preconceived notions (mostly bad), and proper timing (essential). The antimicrobial, antiviral, antitoxic, and binding properties of human α-defensins are summarized. The structural features of α-defensins are described extensively and their functional contributions are assessed. The properties of HD6, an enigmatic Paneth cell α-defensin, are contrasted with those of the four myeloid α-defensins (HNP1-4) and of HD5, the other α-defensin of human Paneth cells. The review ends with a decalogue that may assist researchers or students interested in α-defensins and related aspects of neutrophil function.

  13. Defensins: Potential Effectors in Autoimmune Rheumatic Disorders

    Directory of Open Access Journals (Sweden)

    Stefan Vordenbäumen

    2011-08-01

    Full Text Available Defensins are small cationic peptides with antimicrobial properties. They constitute a highly conserved innate immune defense mechanism across species. Based on the arrangement of disulfide-bonds, α- and β-defensins are distinguished in humans. Both types of defensin comprise several distinct molecules that are preferentially expressed at epithelial surfaces and in blood cells. In the last decade, multiple immunomodulatory functions of defensins have been recognized, including chemotactic activity, the promotion of antigen presentation, and modulations of proinflammatory cytokine secretion. These findings suggested a role for defensins not only as a first line of defense, but also as connectors of innate and adaptive immune responses. Recently, increasingly accumulating evidence has indicated that defensins may also be involved in the pathogenesis of autoimmune rheumatic disorders such as systemic lupus erythematosus and rheumatoid arthritis. The current review summarizes the data connecting defensins to autoimmunity.

  14. Chemical communication of antibiotic resistance by a highly resistant subpopulation of bacterial cells.

    Directory of Open Access Journals (Sweden)

    Omar M El-Halfawy

    Full Text Available The overall antibiotic resistance of a bacterial population results from the combination of a wide range of susceptibilities displayed by subsets of bacterial cells. Bacterial heteroresistance to antibiotics has been documented for several opportunistic Gram-negative bacteria, but the mechanism of heteroresistance is unclear. We use Burkholderia cenocepacia as a model opportunistic bacterium to investigate the implications of heterogeneity in the response to the antimicrobial peptide polymyxin B (PmB and also other bactericidal antibiotics. Here, we report that B. cenocepacia is heteroresistant to PmB. Population analysis profiling also identified B. cenocepacia subpopulations arising from a seemingly homogenous culture that are resistant to higher levels of polymyxin B than the rest of the cells in the culture, and can protect the more sensitive cells from killing, as well as sensitive bacteria from other species, such as Pseudomonas aeruginosa and Escherichia coli. Communication of resistance depended on upregulation of putrescine synthesis and YceI, a widely conserved low-molecular weight secreted protein. Deletion of genes for the synthesis of putrescine and YceI abrogate protection, while pharmacologic inhibition of putrescine synthesis reduced resistance to polymyxin B. Polyamines and YceI were also required for heteroresistance of B. cenocepacia to various bactericidal antibiotics. We propose that putrescine and YceI resemble "danger" infochemicals whose increased production by a bacterial subpopulation, becoming more resistant to bactericidal antibiotics, communicates higher level of resistance to more sensitive members of the population of the same or different species.

  15. Oral biofilms: a reservoir of transferable, bacterial, antimicrobial resistance.

    Science.gov (United States)

    Roberts, Adam P; Mullany, Peter

    2010-12-01

    Oral microbes are responsible for dental caries and periodontal diseases and have also been implicated in a range of other diseases beyond the oral cavity. These bacteria live primarily as complex, polymicrobial biofilms commonly called dental plaque. Cells growing within a biofilm often exhibit altered phenotypes, such as increased antibiotic resistance. The stable structural properties and close proximity of the bacterial cells within the biofilm appears to be an excellent environment for horizontal gene transfer, which can lead to the spread of antibiotic resistance genes amongst the biofilm inhabitants. This article will present an overview of the different types and amount of resistance to antibiotics that have been found in the human oral microbiota and will discuss the oral inhabitants' role as a reservoir of antimicrobial resistance genes. In addition, data on the genetic support for these resistance genes will be detailed and the evidence for horizontal gene transfer reviewed, demonstrating that the bacteria inhabiting the oral cavity are a reservoir of transferable antibiotic resistance.

  16. QTLs for Resistance to Major Rice Diseases Exacerbated by Global Warming: Brown Spot, Bacterial Seedling Rot, and Bacterial Grain Rot.

    Science.gov (United States)

    Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki

    2016-12-01

    In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.

  17. Construction of a Mammary-specific Expression Vector of Human α- defensin- 1 ( HNP- 1) Gene

    Institute of Scientific and Technical Information of China (English)

    Yue YANG; Jing-Ping OU YANG; Bao-Hua WANG

    2005-01-01

    @@ 1 Introduction Defensins, also called human neutrophil peptides(HNP), are small cationic peptides with broad antimicrobial activity[1]. Human defensins are highly abundant in the cytoplasmic granules of polymorphonuclear neutrophils. Alpha-defensin-1 is an important mediator in either innate immunity or anti-infection. It can be developed to be an ideal new type antibiotic and may provide a better solution for the present situation of extensive antibiotics-resistence. It is difficult to achieve amount of antimicrobial peptides from nature sources. Transgenic mammary gland bioreactors offer a safe and cost effective source to produce important proteins. The purpose of this study was to construct a mammary-specific expression plasmid containing beta-lactoglobulin (BLG) gene promoter and human α-defensin-1 (HNP-1) gene.

  18. Antimicrobial resistance of bacterial strains isolated from avian cellulitis

    Directory of Open Access Journals (Sweden)

    MM Santos

    2014-03-01

    Full Text Available Avian cellulitis is an inflammatory process in the subcutaneous tissue, mainly located in the abdomen and thighs. This problem is commonly observed in poultry at slaughter and it is considered one of the major causes of condemnation of carcasses in Brazil. The aim of this study was to perform the microbial isolation of lesions of avian cellulitis from a processing plant located in the State of Goiás in order to analyze antimicrobial resistance by antibiogram test and to detect resistance genes by polymerase chain reaction. A total of 25 samples of avian cellulitis lesions were analyzed, from which 30 bacterial strains were isolated. There were eleven (44% strains of Escherichia coli, nine (36% strains of Staphylococcus epidermidis, seven (28% strains of Proteus mirabilis and three (12% strains of Manheimiahaemolytica. The antibiogram test showed that all strains were resistant to at least one antimicrobial. The gene of antimicrobial resistance tetB was detected in E. coli, S. epidermidis and P. mirabilis strains, and was the most frequently observed gene. The gene of antimicrobial resistance Sul1 was detected in all bacterial species, while tetA was found in E. coli and S. epidermidis strains, SHV in E. coli strains, S. epidermidis and P. mirabilis,and cat1 in one P. mirabilis strain. The results suggest a potential public health hazard due to the ability of these microorganisms to transmit antimicrobial resistancegenes to other microorganisms present in the intestinal tract of humans and animals, which may affect clinical-medical usage of these drugs.

  19. Identification and characterization of antimicrobial peptide, defensin, in the taiga tick, Ixodes persulcatus.

    Science.gov (United States)

    Saito, Y; Konnai, S; Yamada, S; Imamura, S; Nishikado, H; Ito, T; Onuma, M; Ohashi, K

    2009-08-01

    Ixodes persulcatus is the primary vector for human tick-borne diseases in Japan. A cDNA library was constructed from whole body homogenates of fed nymphs of I. persulcatus. From this library, one cDNA encoding defensin-like antimicrobial peptide was identified. The amino-acid sequence showed high similarity to those of the defensins of other ticks and arthropods. I. persulcatus defensin mRNA transcripts were detected at all life cycle stages of fed ticks and found to be predominantly expressed in the midguts of adult female ticks, but not in the salivary glands, a finding corroborated by Western blotting analysis. To investigate the function of I. persulcatus defensin, we examined its antibacterial activity by evaluation of growth of several bacterial strains in the presence of the synthetic peptide. The defensin from I. persulcatus markedly inhibited the growth of Gram-positive bacteria including Staphylococcus aureus, Bacillus subtilis and Corynebacterium renale, but not Gram-negative bacteria except Escherichia coli O157. In conclusion, these results suggest that I. persulcatus defensin may be playing a significant role in the defence against microbes from bloodmeals.

  20. Production of transgenic medaka with increased resistance to bacterial pathogens.

    Science.gov (United States)

    Sarmasik, Aliye; Warr, Gregory; Chen, Thomas T

    2002-06-01

    Cecropins, first identified in silk moth (Hyalophora cecropia), are a group of antimicrobial peptides with bactericidal activity against a broad spectrum of bacteria. In this study we investigated whether (1) this group of antimicrobial peptides could exhibit bactericidal activity toward known fish bacterial pathogens and (2) expression of cecropin transgenes in transgenic medaka (Oryzias latipas) could result in increasing resistance of the transgenic fish to infection by fish bacterial pathogens. Cecropin gene construct containing silk moth preprocecropin B, procecropin B and cecropin B, and porcine cecropin P1 driven by a cytomegalovirus (CMV) promoter were transfected into chinook salmon embryonic cells (CHSE-214) by lipofection, and the resulting permanent transformants were collected. In an "inhibition zone" assay medium isolated from each transformant exhibited strong bactericidal activity toward known fish bacterial pathogens such as Pseudomonas fluorescens, Aeromonas hydrophila, and Vibrio anguillarum. The same cecropin transgene constructs were introduced into newly fertilized medaka eggs by electroporation to produce transgenic fish. About 40% to 60% of the embryos survived from electroporation, and about 5% to 11% of the surviving fish were shown to contain cecropin transgenes by polymerase chain reaction analysis of genomic DNA samples isolated from presumptive transgenic fish. These P1 transgenic fish were used as founder stocks, and following generations of successive breeding, a total of 20 F2 families of transgenic fish were established. Expression of cecropin transgenes was detected in the F2 transgenics by reverse transcriptase polymerase chain reaction analysis. Southern blot analysis of genomic DNA isolated from different F2 fish showed that cecropin transgenes were integrated into the genomes of F2 transgenic fish. To determine whether transgenic fish carrying cecropin transgenes could exhibit resistance to infection by known fish bacterial

  1. Antibiotic resistance in prevalent bacterial and protozoan sexually transmitted infections

    Directory of Open Access Journals (Sweden)

    Karl Krupp

    2015-01-01

    Full Text Available The emergence of multi-drug resistant sexually transmitted infections (STIs is causing a treatment crisis across the globe. While cephalosporin-resistant gonorrhea is one of the most pressing issues, extensively antibiotic resistant Chlamydia trachomatis and Mycoplasma hominis are also becoming commonplace. Experts have suggested that the failure of current treatment regimens are "largely inevitable" and have called for entirely new classes of antimicrobial agents. With the exception of several new classes of drugs primarily targeting nosocomial infections, progress has been slow. While pharmaceutical companies continue to introduce new drugs, they are based on decade-old discoveries. While there is disagreement about what constitutes new classes of antibiotics, many experts suggest that the last truly new family of antimicrobials was discovered in 1987. This review summarizes the existing literature on antibiotic resistance in common bacterial and protozoal STIs. It also briefly discusses several of the most promising alternatives to current therapies, and further examines how advances in drug delivery, formulation, concentration, and timing are improving the efficacy of existing treatments. Finally, the paper discusses the current state of pharmaceutical development for multidrug-resistant STI.

  2. STUDY OF BACTERIAL RESISTANCE TO ORGANOPHOSPHOROUS PESTICIDES IN IRAN

    Directory of Open Access Journals (Sweden)

    A. Nazarian and M. Mousawi

    2005-07-01

    Full Text Available The broadness application of organophosphorus compounds has abounded the number of its polluted areas. Bioremediation has widely focused on insitu bacterial degradation of organophosphorus residues in the world. Therefore, in this research six numbers of samples from two different sources, soil and water randomly were isolated using different organophosphorus pesticides containing mineral solution without supplementation. More than 100 isolated strains were selected according to their simultaneous optimal growth on mineral medium with organophosphorus and Mac Conkey,s agar. More than 50 percent of them were lost above resistance. The resistant strains were identified by two methods, the biochemical convention and API 20E procedure with positive agreement. The identified strains belonged to Pseudomonas and Flavobacterium species. The maximum tolerant concentrations of different organophosphorus pesticides by these resistant strains were 2.5, 4 and 8 g/L of guthion, methyl parathion and Dimethoate, respectively. The resistance to these pesticides due to organ phosphorous degrading plasmids had the ability to express hydrolytic enzymes. Resistant bacteria lost these plasmids by acridin orange and could translocate to sensitive strains. Thus, certain environmental bacteria could be used as protection tools against antinerve agents.

  3. Bacterial spore structures and their protective role in biocide resistance.

    Science.gov (United States)

    Leggett, M J; McDonnell, G; Denyer, S P; Setlow, P; Maillard, J-Y

    2012-09-01

    The structure and chemical composition of bacterial spores differ considerably from those of vegetative cells. These differences largely account for the unique resistance properties of the spore to environmental stresses, including disinfectants and sterilants, resulting in the emergence of spore-forming bacteria such as Clostridium difficile as major hospital pathogens. Although there has been considerable work investigating the mechanisms of action of many sporicidal biocides against Bacillus subtilis spores, there is far less information available for other species and particularly for various Clostridia. This paucity of information represents a major gap in our knowledge given the importance of Clostridia as human pathogens. This review considers the main spore structures, highlighting their relevance to spore resistance properties and detailing their chemical composition, with a particular emphasis on the differences between various spore formers. Such information will be vital for the rational design and development of novel sporicidal chemistries with enhanced activity in the future.

  4. How to Measure Export via Bacterial Multidrug Resistance Efflux Pumps

    Directory of Open Access Journals (Sweden)

    Jessica M. A. Blair

    2016-07-01

    Full Text Available Bacterial multidrug resistance (MDR efflux pumps are an important mechanism of antibiotic resistance and are required for many pathogens to cause infection. They are also being harnessed to improve microbial biotechnological processes, including biofuel production. Therefore, scientists of many specialties must be able to accurately measure efflux activity. However, myriad methodologies have been described and the most appropriate method is not always clear. Within the scientific literature, many methods are misused or data arising are misinterpreted. The methods for measuring efflux activity can be split into two groups, (i those that directly measure efflux and (ii those that measure the intracellular accumulation of a substrate, which is then used to infer efflux activity. Here, we review the methods for measuring efflux and explore the most recent advances in this field, including single-cell or cell-free technologies and mass spectrometry, that are being used to provide more detailed information about efflux pump activity.

  5. Sterilization Resistance of Bacterial Spores Explained with Water Chemistry.

    Science.gov (United States)

    Friedline, Anthony W; Zachariah, Malcolm M; Middaugh, Amy N; Garimella, Ravindranath; Vaishampayan, Parag A; Rice, Charles V

    2015-11-01

    Bacterial spores can survive for long periods without nutrients and in harsh environmental conditions. This survival is influenced by the structure of the spore, the presence of protective compounds, and water retention. These compounds, and the physical state of water in particular, allow some species of bacterial spores to survive sterilization schemes with hydrogen peroxide and UV light. The chemical nature of the spore core and its water has been a subject of some contention and the chemical environment of the water impacts resistance paradigms. Either the spore has a glassy core, where water is immobilized along with other core components, or the core is gel-like with mobile water diffusion. These properties affect the movement of peroxide and radical species, and hence resistance. Deuterium solid-state NMR experiments are useful for examining the nature of the water inside the spore. Previous work in our lab with spores of Bacillus subtilis indicate that, for spores, the core water is in a more immobilized state than expected for the gel-like core theory, suggesting a glassy core environment. Here, we report deuterium solid-state NMR observations of the water within UV- and peroxide-resistant spores from Bacillus pumilus SAFR-032. Variable-temperature NMR experiments indicate no change in the line shape after heating to 50 °C, but an overall decrease in signal after heating to 100 °C. These results show glass-like core dynamics within B. pumilus SAFR-032 that may be the potential source of its known UV-resistance properties. The observed NMR traits can be attributed to the presence of an exosporium containing additional labile deuterons that can aid in the deactivation of sterilizing agents.

  6. Antifungal agents: mode of action, mechanisms of resistance, and correlation of these mechanisms with bacterial resistance.

    Science.gov (United States)

    Ghannoum, M A; Rice, L B

    1999-10-01

    The increased use of antibacterial and antifungal agents in recent years has resulted in the development of resistance to these drugs. The significant clinical implication of resistance has led to heightened interest in the study of antimicrobial resistance from different angles. Areas addressed include mechanisms underlying this resistance, improved methods to detect resistance when it occurs, alternate options for the treatment of infections caused by resistant organisms, and strategies to prevent and control the emergence and spread of resistance. In this review, the mode of action of antifungals and their mechanisms of resistance are discussed. Additionally, an attempt is made to discuss the correlation between fungal and bacterial resistance. Antifungals can be grouped into three classes based on their site of action: azoles, which inhibit the synthesis of ergosterol (the main fungal sterol); polyenes, which interact with fungal membrane sterols physicochemically; and 5-fluorocytosine, which inhibits macromolecular synthesis. Many different types of mechanisms contribute to the development of resistance to antifungals. These mechanisms include alteration in drug target, alteration in sterol biosynthesis, reduction in the intercellular concentration of target enzyme, and overexpression of the antifungal drug target. Although the comparison between the mechanisms of resistance to antifungals and antibacterials is necessarily limited by several factors defined in the review, a correlation between the two exists. For example, modification of enzymes which serve as targets for antimicrobial action and the involvement of membrane pumps in the extrusion of drugs are well characterized in both the eukaryotic and prokaryotic cells.

  7. Study of Bacterial Resistance against Antibiotics in Patients Body Fluid Germs

    OpenAIRE

    2007-01-01

    Background: Increase of bacterial resistance against antibiotics makes some difficulties in patient’s treatment and it is essential to study of antibiotics situation and bacterial sensitivity pattern against antibiotics. Physicians often get soon start to treatment patients based on bacterial quantities and bacterial sensitivity against antibiotics that seem always is not an effective treatment and make to spread some resistant species against antibiotics and increase their quantities in popu...

  8. Development of resistant tomato population with bacterial canker resistance genes from interspecific hybrids by the support of embryo rescue

    OpenAIRE

    Aylin KABAŞ; Esin ARI; Sinan ZENGİN; Hülya İLBİ; AYSAN, Yeşim; Asu OĞUZ

    2016-01-01

    Bacterial canker is one of the most important diseases causing economic yield loss in tomato production areas in the world. The best way to control for this disease is to use resistant varieties. However, there are few studies on variety breeding studies of this disease compared with other disease resistant breeding studies. In this study we aimed to improve inbred lines carrying bacterial canker resistance genes to use in the breeding of resistant varieties. Susceptible inbred line AK1 (S. e...

  9. The Fungal Defensin Family Enlarged

    Directory of Open Access Journals (Sweden)

    Jiajia Wu

    2014-08-01

    Full Text Available Fungi are an emerging source of peptide antibiotics. With the availability of a large number of model fungal genome sequences, we can expect that more and more fungal defensin-like peptides (fDLPs will be discovered by sequence similarity search. Here, we report a total of 69 new fDLPs encoded by 63 genes, in which a group of fDLPs derived from dermatophytes are defined as a new family (fDEF8 according to sequence and phylogenetic analyses. In the oleaginous fungus Mortierella alpine, fDLPs have undergone extensive gene expansion. Our work further enlarges the fungal defensin family and will help characterize new peptide antibiotics with therapeutic potential.

  10. Performance of resistance gene pyramids to races of rice bacterial blight in Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    ZHENGKangle; ZHUANGJieyun; WANGHanrong

    1998-01-01

    The effect of gene pyramiding on resistance to bacterial blight (BB) in rice was evahlated among the IR24-based near isogenic lines conraining single resistance gene and gene pyramids containing two, three or lour resistancegenes (see table).

  11. 75 FR 33317 - Antibacterial Resistance and Diagnostic Device and Drug Development Research for Bacterial...

    Science.gov (United States)

    2010-06-11

    ... Development Research for Bacterial Diseases; Public Workshop AGENCY: Food and Drug Administration, HHS. ACTION.... The workshop will address antibacterial drug resistance, mechanisms of resistance, epidemiology of... Drug Evaluation and Research, Food and Drug Administration, Office of Antimicrobial Products, 10903...

  12. Salmonella serovar specific upregulation of porcine defensins 1 and 2 in a jejunal epithelial cell line

    NARCIS (Netherlands)

    Veldhuizen, E.J.A.; Koomen, I; Ultee, A.; van Dijk, A.; Haagsman, H.P.

    2009-01-01

    Defensins are important antimicrobial effector peptides of the innate immune system, which provides protection against bacterial infections in the intestine. Salmonella Choleraesuis and Salmonella Typhimurium are the most commonly isolated serovars in pig, but disease outcome is dependent on the Sal

  13. Monopoly pricing of an antibiotic subject to bacterial resistance.

    Science.gov (United States)

    Herrmann, Markus

    2010-01-01

    We develop a dynamic bio-economic model of bacterial resistance and disease transmission in which we characterize the pricing policy of a monopolist who is protected by a patent. After expiration, the monopolist behaves competitively in a generic industry having open access to the common pool of antibiotic efficacy and infection. The monopolist manages endogenously the levels of antibiotic efficacy as well as the infected population, which represent quality and market size respectively and achieves, at least temporarily, higher such levels than a hypothetically myopic monopolist who does not take into account the dynamic externalities. The pricing policy and the biological system is characterized by the turnpike property. Before the patent vanishes, the monopolist behaves more and more myopically, leading to a continuous decrease in the price of the antibiotic. Once the generic industry takes over, a discontinuous fall in price occurs. Whether a prolongation of the patent is socially desirable depends on the relative levels of antibiotic efficacy and infection.

  14. Modulation of Bacterial Multidrug Resistance Efflux Pumps of the Major Facilitator Superfamily

    Directory of Open Access Journals (Sweden)

    Sanath Kumar

    2013-01-01

    Full Text Available Bacterial infections pose a serious public health concern, especially when an infectious disease has a multidrug resistant causative agent. Such multidrug resistant bacteria can compromise the clinical utility of major chemotherapeutic antimicrobial agents. Drug and multidrug resistant bacteria harbor several distinct molecular mechanisms for resistance. Bacterial antimicrobial agent efflux pumps represent a major mechanism of clinical resistance. The major facilitator superfamily (MFS is one of the largest groups of solute transporters to date and includes a significant number of bacterial drug and multidrug efflux pumps. We review recent work on the modulation of multidrug efflux pumps, paying special attention to those transporters belonging primarily to the MFS.

  15. Bacterial resistance to antisense peptide phosphorodiamidate morpholino oligomers.

    Science.gov (United States)

    Puckett, Susan E; Reese, Kaleb A; Mitev, Georgi M; Mullen, Valerie; Johnson, Rudd C; Pomraning, Kyle R; Mellbye, Brett L; Tilley, Lucas D; Iversen, Patrick L; Freitag, Michael; Geller, Bruce L

    2012-12-01

    Peptide phosphorodiamidate morpholino oligomers (PPMOs) are synthetic DNA mimics that bind cRNA and inhibit bacterial gene expression. The PPMO (RFF)(3)RXB-AcpP (where R is arginine, F, phenylalanine, X is 6-aminohexanoic acid, B is β-alanine, and AcpP is acyl carrier protein) is complementary to 11 bases of the essential gene acpP (which encodes acyl carrier protein). The MIC of (RFF)(3)RXB-AcpP was 2.5 μM (14 μg/ml) in Escherichia coli W3110. The rate of spontaneous resistance of E. coli to (RFF)(3)RXB-AcpP was 4 × 10(-7) mutations/cell division. A spontaneous (RFF)(3)RXB-AcpP-resistant mutant (PR200.1) was isolated. The MIC of (RFF)(3)RXB-AcpP was 40 μM (224 μg/ml) for PR200.1. The MICs of standard antibiotics for PR200.1 and W3110 were identical. The sequence of acpP was identical in PR200.1 and W3110. PR200.1 was also resistant to other PPMOs conjugated to (RFF)(3)RXB or peptides with a similar composition or pattern of cationic and nonpolar residues. Genomic sequencing of PR200.1 identified a mutation in sbmA, which encodes an active transport protein. In separate experiments, a (RFF)(3)RXB-AcpP-resistant isolate (RR3) was selected from a transposome library, and the insertion was mapped to sbmA. Genetic complementation of PR200.1 or RR3 with sbmA restored susceptibility to (RFF)(3)RXB-AcpP. Deletion of sbmA caused resistance to (RFF)(3)RXB-AcpP. We conclude that resistance to (RFF)(3)RXB-AcpP was linked to the peptide and not the phosphorodiamidate morpholino oligomer, dependent on the composition or repeating pattern of amino acids, and caused by mutations in sbmA. The data further suggest that (RFF)(3)R-XB PPMOs may be transported across the plasma membrane by SbmA.

  16. Inheritance of resistance to bacterial streak and hacterial blight in rice

    Institute of Scientific and Technical Information of China (English)

    XUJianlong; WANGHanrong; LINYi; XIYongan

    1998-01-01

    Bacterial streak(BS) caused by Xanthomonas campesiris pv. oryzicola bas become one of the major diseases in southbern rice areas.Up to date, tbere are few reports on the inheritance of resistance to BS and its relationsbip with the resistance to bacterial blight(BB).

  17. Sustainable control of pea bacterial blight : approaches for durable genetic resistance and biocontrol by endophytic bacteria

    NARCIS (Netherlands)

    Elvira-Recuenco, M.

    2000-01-01

    Key-words: bacterial blight, biological control, biodiversity, endophytic bacteria, L-form, pea, PDRl retrotransposon, Pisum sativum, Pisum abyssinicum, Pseudomonas syringae pv. pisi, race specific resistance, race non-specific resistance, Spanish landraces.Pea bacterial blight (Pseudom

  18. Scorpion Potassium Channel-blocking Defensin Highlights a Functional Link with Neurotoxin.

    Science.gov (United States)

    Meng, Lanxia; Xie, Zili; Zhang, Qian; Li, Yang; Yang, Fan; Chen, Zongyun; Li, Wenxin; Cao, Zhijian; Wu, Yingliang

    2016-03-25

    The structural similarity between defensins and scorpion neurotoxins suggests that they might have evolved from a common ancestor. However, there is no direct experimental evidence demonstrating a functional link between scorpion neurotoxins and defensins. The scorpion defensin BmKDfsin4 from Mesobuthus martensiiKarsch contains 37 amino acid residues and a conserved cystine-stabilized α/β structural fold. The recombinant BmKDfsin4, a classical defensin, has been found to have inhibitory activity against Gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis, and Micrococcus luteusas well as methicillin-resistant Staphylococcus aureus Interestingly, electrophysiological experiments showed that BmKDfsin4,like scorpion potassium channel neurotoxins, could effectively inhibit Kv1.1, Kv1.2, and Kv1.3 channel currents, and its IC50value for the Kv1.3 channel was 510.2 nm Similar to the structure-function relationships of classical scorpion potassium channel-blocking toxins, basic residues (Lys-13 and Arg-19) of BmKDfsin4 play critical roles in peptide-Kv1.3 channel interactions. Furthermore, mutagenesis and electrophysiological experiments demonstrated that the channel extracellular pore region is the binding site of BmKDfsin4, indicating that BmKDfsin4 adopts the same mechanism for blocking potassium channel currents as classical scorpion toxins. Taken together, our work identifies scorpion BmKDfsin4 as the first invertebrate defensin to block potassium channels. These findings not only demonstrate that defensins from invertebrate animals are a novel type of potassium channel blockers but also provide evidence of a functional link between defensins and neurotoxins.

  19. Immunomodulatory properties of defensins and cathelicidins.

    Science.gov (United States)

    Bowdish, D M E; Davidson, D J; Hancock, R E W

    2006-01-01

    Host defence peptides are a conserved component of the innate immune response in all complex life forms. In humans, the major classes of host defence peptides include the alpha- and beta-defensins and the cathelicidin, hCAP-18/LL-37. These peptides are expressed in the granules of neutrophils and by a wide variety of tissue types. They have many roles in the immune response including both indirect and direct antimicrobial activity, the ability to act as chemokines as well as induce chemokine production leading to recruitment of leukocytes to the site of infection, the promotion of wound healing and an ability to modulate adaptive immunity. It appears that many of these properties are mediated though direct interaction of peptides with the cells of the innate immune response including monocytes, dendritic cells, T cells and epithelial cells. The importance of these peptides in immune responses has been demonstrated since animals defective in the expression of certain host defence peptides show greater susceptibility to bacterial infections. In the very few instances in which human patients have been demonstrated to have defective host defence peptide expression, these individuals suffer from frequent infections. Although studies of the immunomodulatory properties of these peptides are in their infancy, there is a growing body of evidence suggesting that the immunomodulatory properties of these small, naturally occurring molecules might be harnessed for development as novel therapeutic agents.

  20. Structure-dependent charge density as a determinant of antimicrobial activity of peptide analogues of defensin.

    Science.gov (United States)

    Bai, Yang; Liu, Shouping; Jiang, Ping; Zhou, Lei; Li, Jing; Tang, Charles; Verma, Chandra; Mu, Yuguang; Beuerman, Roger W; Pervushin, Konstantin

    2009-08-01

    Defensins are small (3-5 kDa) cysteine-rich cationic proteins found in both vertebrates and invertebrates constituting the front line of host innate immunity. Despite intensive research, bactericidal and cytotoxic mechanisms of defensins are still largely unknown. Moreover, we recently demonstrated that small peptides derived from defensins are even more potent bactericidal agents with less toxicity toward host cells. In this paper, structures of three C-terminal (R36-K45) analogues of human beta-defensin-3 were studied by 1H NMR spectroscopy and extensive molecular dynamics simulations. Because of indications that these peptides might target the inner bacterial membrane, they were reconstituted in dodecylphosphocholine or dodecylphosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] mixed micelles, and lipid bicelles mimicking the phospholipid-constituted bilayer membrane of mammalian and bacterial cells. The results show that the binding affinity and partitioning into the lipid phase and the ability to dimerize and accrete well-defined structures upon interactions with lipid membranes contribute to compactization of positive charges within peptide oligomers. The peptide charge density, mediated by corresponding three-dimensional structures, was found to directly correlate with the antimicrobial activity. These novel observations may provide a new rationale for the design of improved antimicrobial agents.

  1. The first salamander defensin antimicrobial peptide.

    Directory of Open Access Journals (Sweden)

    Ping Meng

    Full Text Available Antimicrobial peptides have been widely identified from amphibian skins except salamanders. A novel antimicrobial peptide (CFBD was isolated and characterized from skin secretions of the salamander, Cynops fudingensis. The cDNA encoding CFBD precursor was cloned from the skin cDNA library of C. fudingensis. The precursor was composed of three domains: signal peptide of 17 residues, mature peptide of 41 residues and intervening propeptide of 3 residues. There are six cysteines in the sequence of mature CFBD peptide, which possibly form three disulfide-bridges. CFBD showed antimicrobial activities against Staphylococcus aureus, Bacillus subtilis, Candida albicans and Escherichia coli. This peptide could be classified into family of β-defensin based on its sequence similarity with β-defensins from other vertebrates. Evolution analysis indicated that CFBD was close to fish β-defensin. As far as we know, CFBD is the first β-defensin antimicrobial peptide from salamanders.

  2. Tagging RAPD markers to a bacterial blight resistance gene in rice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@The somaclonal mutant HX_3 has shown a broad spectrum resistance to bacterial blight. To study the inheritance of the bacterial blight resistance in HX_3, a cross was made between HX_3 and a susceptible cultivar Longtefu A. The F2 population of 418 plants was inoculated with Chinese bacterial blight strain Zhe 173 (pathotype Ⅳ ). Results showed that the F2 progenies segregated in a ratio of 3R∶ 1S (324 resistant plants and 94 susceptible plants). From the plants tested, 114 individuals (86 resistant and 28 susceptible) were chosen randomly for RAPD analysis. Twelve highly resistant and 12 highly susceptible plants were selected to form a resistant pool and a susceptible pool, respectively.

  3. Application of hordothionins and cecropin B for engineering bacterial disease resistance into plants.

    NARCIS (Netherlands)

    Florack, D.

    1994-01-01

    Bacterial diseases can cause a drastic decrease of yield in certain crops. Breeding for bacterial disease resistance therefore is of utmost necessity. Up to now, traditional plant breeding was the only method to reach this goal. Recent developments in genetic engineering technology however provide n

  4. Phenotypic resistance and the dynamics of bacterial escape from phage control

    DEFF Research Database (Denmark)

    Bull, James J.; Vegge, Christina Skovgaard; Schmerer, Matthew

    2014-01-01

    The canonical view of phage - bacterial interactions in dense, liquid cultures is that the phage will eliminate most of the sensitive cells; genetic resistance will then ascend to restore high bacterial densities. Yet there are various mechanisms by which bacteria may remain sensitive to phages...... mathematical models of these processes and suggest how different types of this 'phenotypic' resistance may be elucidated. We offer preliminary in vitro studies of a previously characterized E. coli model system and Campylobacter jejuni illustrating apparent phenotypic resistance. As phenotypic resistance may...

  5. In vitro sensitivity of oral, gram-negative, facultative bacteria to the bactericidal activity of human neutrophil defensins.

    Science.gov (United States)

    Miyasaki, K T; Bodeau, A L; Ganz, T; Selsted, M E; Lehrer, R I

    1990-12-01

    Neutrophils play a major role in defending the periodontium against infection by oral, gram-negative, facultative bacteria, such as Actinobacillus actinomycetemcomitans, Eikenella corrodens, and Capnocytophaga spp. We examined the sensitivity of these bacteria to a mixture of low-molecular-weight peptides and highly purified individual defensin peptides (HNP-1, HNP-2, and HNP-3) isolated from human neutrophils. Whereas the Capnocytophaga spp. strains were killed significantly by the mixed human neutrophil peptides, the A. actinomycetemcomitans and E. corrodens strains were resistant. Killing was attributable to the defensins. The bactericidal activities of purified defensins HNP-1 and HNP-2 were equal, and both of these activities were greater than HNP-3 activity against strains of Capnocytophaga sputigena and Capnocytophaga gingivalis. The strain of Capnocytophaga ochracea was more sensitive to defensin-mediated bactericidal activity than either C. sputigena or C. gingivalis was. The three human defensins were equipotent in killing C. ochracea. C. ochracea was killed under aerobic and anaerobic conditions and over a broad pH range. Killing was most effective under hypotonic conditions but also occurred at physiologic salt concentrations. We concluded that Capnocytophaga spp. are sensitive to oxygen-independent killing by human defensins. Additional studies will be required to identify other components that may equip human neutrophils to kill A. actinomycetemcomitans, E. corrodens, and other oral gram-negative bacteria.

  6. Evolution of antibiotic resistance is linked to any genetic mechanism affecting bacterial duration of carriage

    Science.gov (United States)

    Lehtinen, Sonja; Blanquart, François; Croucher, Nicholas J.; Turner, Paul; Lipsitch, Marc; Fraser, Christophe

    2017-01-01

    Understanding how changes in antibiotic consumption affect the prevalence of antibiotic resistance in bacterial pathogens is important for public health. In a number of bacterial species, including Streptococcus pneumoniae, the prevalence of resistance has remained relatively stable despite prolonged selection pressure from antibiotics. The evolutionary processes allowing the robust coexistence of antibiotic sensitive and resistant strains are not fully understood. While allelic diversity can be maintained at a locus by direct balancing selection, there is no evidence for such selection acting in the case of resistance. In this work, we propose a mechanism for maintaining coexistence at the resistance locus: linkage to a second locus that is under balancing selection and that modulates the fitness effect of resistance. We show that duration of carriage plays such a role, with long duration of carriage increasing the fitness advantage gained from resistance. We therefore predict that resistance will be more common in strains with a long duration of carriage and that mechanisms maintaining diversity in duration of carriage will also maintain diversity in antibiotic resistance. We test these predictions in S. pneumoniae and find that the duration of carriage of a serotype is indeed positively correlated with the prevalence of resistance in that serotype. These findings suggest heterogeneity in duration of carriage is a partial explanation for the coexistence of sensitive and resistant strains and that factors determining bacterial duration of carriage will also affect the prevalence of resistance. PMID:28096340

  7. Effect of Vibration on Bacterial Growth and Antibiotic Resistance

    Science.gov (United States)

    Juergensmeyer, Elizabeth A.; Juergensmeyer, Margaret A.

    2004-01-01

    The purpose of this research grant was to provide a fundamental, systematic investigation of the effects of oscillatory acceleration on bacterial proliferation and their responses to antibiotics in a liquid medium.

  8. Genetics and Improvement of Bacterial Blight Resistance of Hybrid Rice in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qi

    2009-01-01

    Since 1980s, rice breeding for resistance to bacterial blight has been rapidly progressing in China. The gene Xa4 was mainly used in three-line indica hybrid and two-line hybrid rice. The disease has been 'quiet' for 20 years in China, yet in recent years it has gradually emerged and been prevalent in fields planted with newly released rice varieties in the Changjiang River valley. Under the circumstances, scientists inevitably raised several questions: what causes the resurgence and what should we do next? And/or is resistance breeding still one of the main objectives in rice improvement? Which approach do we take on resistance breeding so that the resistance will be more durable, and the resistance gene will be used more efficiently? A combined strategy involving traditional method, molecular marker-assisted selection, and transgenic technology should bring a new era to the bacterial blight resistance hybrid rice breeding program. This review also briefly discusses and deliberates on issues related to the broadening of bacterial blight resistance, and suitable utilization of resistance genes, alternate planting of available resistance genes; and understands the virulent populations of the bacterial pathogen in China even in Asia.

  9. Bacterial resistance and impetigo treatment trends: a review.

    Science.gov (United States)

    Bangert, Scott; Levy, Moise; Hebert, Adelaide A

    2012-01-01

    Impetigo is a common cutaneous infection that is especially prevalent in children. The prevalence of colonization and infection with resistant strains is continually increasing, forcing clinicians to reevaluate treatment strategies. Newer topical agents are effective in treating infections with resistant strains and may help minimize resistance and adverse effects from systemic agents. Use of topical disinfectants to decrease colonization is an important adjunctive measure. Physicians should be aware of local resistance patterns in impetigo to help guide therapy.

  10. ß-defensin-2 in breast milk displays a broad antimicrobial activity against pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Joanna Baricelli

    2015-02-01

    Full Text Available OBJECTIVE: To describe the antimicrobial activity of ß-defensin-2 produced in the mammary gland and secreted in human breast milk. METHODS: The peptide production was performed by DNA cloning. ß-defensin-2 levels were quantified in 61 colostrum samples and 39 mature milk samples from healthy donors, by an indirect enzyme-linked immunosorbent assay (ELISA. Using halo inhibition assay, this study assessed activity against seven clinical isolates from diarrheal feces of children between 0 and 2 years of age. The activity of ß-defensin-2 against three opportunistic pathogens that can cause nosocomial infections was determined by microdilution test. RESULTS: The peptide levels were higher in colostrum (n = 61 than in mature milk samples (n = 39, as follows: median and range, 8.52 (2.6-16.3 µg/ml versus 0.97 (0.22-3.78, p < 0.0001; Mann-Whitney test. The recombinant peptide obtained showed high antimicrobial activity against a broad range of pathogenic bacteria. Its antibacterial activity was demonstrated in a disk containing between 1-4 µg, which produced inhibition zones ranging from 18 to 30 mm against three isolates of Salmonella spp. and four of E. coli. ß-defensin-2 showed minimum inhibitory concentrations (MICs of 0.25 µg/mL and 0.5 µg/mL for S. marcescen and P. aeruginosa, respectively, while a higher MIC (4 µg/mL was obtained against an isolated of multidrug-resistant strain of A. baumannii. CONCLUSIONS: To the authors' knowledge, this study is the first to report ß-defensin-2 levels in Latin American women. The production and the activity of ß-defensin-2 in breast milk prove its importance as a defense molecule for intestinal health in pediatric patients.

  11. [Advances in molecular mechanisms of bacterial resistance caused by stress-induced transfer of resistance genes--a review].

    Science.gov (United States)

    Sun, Dongchang; Wang, Bing; Zhu, Lihong

    2013-07-04

    The transfer of resistance gene is one of the most important causes of bacterial resistance. Recent studies reveal that stresses induce the transfer of antibiotic resistance gene through multiple mechanisms. DNA damage stresses trigger bacterial SOS response and induce the transfer of resistance gene mediated by conjugative DNA. Antibiotic stresses induce natural bacterial competence for transformation in some bacteria which lack the SOS system. In addition, our latest studies show that the general stress response regulator RpoS regulates a novel type of resistance gene transfer which is mediated by double-stranded plasmid DNA and occurs exclusively on the solid surface. In this review, we summarized recent advances in SOS dependent and independent stress-induced DNA transfer which is mediated by conjugation and transformation respectively, and the transfer of double-stranded plasmid DNA on the solid surface which is regulated by RpoS. We propose that future work should address how stresses activate the key regulators and how these regulators control the expression of gene transfer related genes. Answers to the above questions would pave the way for searching for candidate targets for controlling bacterial resistance resulted from the transfer of antibiotic genes.

  12. Antibacterial and antifungal activity of a snakin-defensin hybrid protein expressed in tobacco and potato plants

    Science.gov (United States)

    In this study, for the first time, functionally active recombinant cysteine-rich plant proteins snakin-1 (SN1) and defensin (PTH1) were successfully expressed and purified using a prokaryotic (bacterial) expression system. The overall level of antimicrobial activities of SN1 and PTH1 produced in Esc...

  13. Defensive remodeling: How bacterial surface properties and biofilm formation promote resistance to antimicrobial peptides.

    Science.gov (United States)

    Nuri, Reut; Shprung, Tal; Shai, Yechiel

    2015-11-01

    Multidrug resistance bacteria are a major concern worldwide. These pathogens cannot be treated with conventional antibiotics and thus alternative therapeutic agents are needed. Antimicrobial peptides (AMPs) are considered to be good candidates for this purpose. Most AMPs are short and positively charged amphipathic peptides, which are found in all known forms of life. AMPs are known to kill bacteria by binding to the negatively charged bacterial surface, and in most cases cause membrane disruption. Resistance toward AMPs can be developed, by modification of bacterial surface molecules, secretion of protective material and up-regulation or elimination of specific proteins. Because of the general mechanisms of attachment and action of AMPs, bacterial resistance to AMPs often involves biophysical and biochemical changes such as surface rigidity, cell wall thickness, surface charge, as well as membrane and cell wall modification. Here we focus on the biophysical, surface and surrounding changes that bacteria undergo in acquiring resistance to AMPs. In addition we discuss the question of whether bacterial resistance to administered AMPs might compromise our innate immunity to endogenous AMPs. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.

  14. Synergistic effect of interleukin 1 alpha on nontypeable Haemophilus influenzae-induced up-regulation of human beta-defensin 2 in middle ear epithelial cells

    Directory of Open Access Journals (Sweden)

    Park Raekil

    2006-01-01

    Full Text Available Abstract Background We recently showed that beta-defensins have antimicrobial activity against nontypeable Haemophilus influenzae (NTHi and that interleukin 1 alpha (IL-1 alpha up-regulates the transcription of beta-defensin 2 (DEFB4 according to new nomenclature of the Human Genome Organization in human middle ear epithelial cells via a Src-dependent Raf-MEK1/2-ERK signaling pathway. Based on these observations, we investigated if human middle ear epithelial cells could release IL-1 alpha upon exposure to a lysate of NTHi and if this cytokine could have a synergistic effect on beta-defensin 2 up-regulation by the bacterial components. Methods The studies described herein were carried out using epithelial cell lines as well as a murine model of acute otitis media (OM. Human cytokine macroarray analysis was performed to detect the released cytokines in response to NTHi exposure. Real time quantitative PCR was done to compare the induction of IL-1 alpha or beta-defensin 2 mRNAs and to identify the signaling pathways involved. Direct activation of the beta-defensin 2 promoter was monitored using a beta-defensin 2 promoter-Luciferase construct. An IL-1 alpha blocking antibody was used to demonstrate the direct involvement of this cytokine on DEFB4 induction. Results Middle ear epithelial cells released IL-1 alpha when stimulated by NTHi components and this cytokine acted in an autocrine/paracrine synergistic manner with NTHi to up-regulate beta-defensin 2. This synergistic effect of IL-1 alpha on NTHi-induced beta-defensin 2 up-regulation appeared to be mediated by the p38 MAP kinase pathway. Conclusion We demonstrate that IL-1 alpha is secreted by middle ear epithelial cells upon exposure to NTHi components and that it can synergistically act with certain of these molecules to up-regulate beta-defensin 2 via the p38 MAP kinase pathway.

  15. Effects of antibiotic resistance alleles on bacterial evolutionary responses to viral parasites.

    Science.gov (United States)

    Arias-Sánchez, Flor I; Hall, Alex R

    2016-05-01

    Antibiotic resistance has wide-ranging effects on bacterial phenotypes and evolution. However, the influence of antibiotic resistance on bacterial responses to parasitic viruses remains unclear, despite the ubiquity of such viruses in nature and current interest in therapeutic applications. We experimentally investigated this by exposing various Escherichia coli genotypes, including eight antibiotic-resistant genotypes and a mutator, to different viruses (lytic bacteriophages). Across 960 populations, we measured changes in population density and sensitivity to viruses, and tested whether variation among bacterial genotypes was explained by their relative growth in the absence of parasites, or mutation rate towards phage resistance measured by fluctuation tests for each phage. We found that antibiotic resistance had relatively weak effects on adaptation to phages, although some antibiotic-resistance alleles impeded the evolution of resistance to phages via growth costs. By contrast, a mutator allele, often found in antibiotic-resistant lineages in pathogenic populations, had a relatively large positive effect on phage-resistance evolution and population density under parasitism. This suggests costs of antibiotic resistance may modify the outcome of phage therapy against pathogenic populations previously exposed to antibiotics, but the effects of any co-occurring mutator alleles are likely to be stronger.

  16. Evolution of resistance to a last-resort antibiotic in Staphyloccocus aureus via bacterial competition

    Science.gov (United States)

    Koch, Gudrun; Yepes, Ana; Förstner, Konrad U.; Wermser, Charlotte; Stengel, Stephanie T.; Modamio, Jennifer; Ohlsen, Knut; Foster, Kevin R.; Lopez, Daniel

    2014-01-01

    Summary Antibiotic resistance is a key medical concern, with antibiotic use likely being an important cause. However, here we describe an alternative route to clinically-relevant antibiotic resistance that occurs solely due to competitive interactions between bacterial cells. We consistently observe that isolates of Methicillin-resistant Staphylococcus aureus diversify spontaneously into two distinct, sequentially arising strains. The first evolved strain outgrows the parent strain via secretion of surfactants and a toxic bacteriocin. The second is resistant to the bacteriocin. Importantly, this second strain is also resistant to intermediate levels of vancomycin. This so-called VISA (vancomycin-intermediate S. aureus) phenotype is seen in many hard-to-treat clinical isolates. This strain diversification also occurs during in vivo infection in a mouse model, consistent with the fact that both coevolved phenotypes resemble strains commonly found in clinic. Our study shows how competition between coevolving bacterial strains can generate antibiotic resistance and recapitulate key clinical phenotypes. PMID:25171407

  17. Antimicrobial activities of chicken β -defensin (4 and 10 peptides against pathogenic bacteria and fungi

    Directory of Open Access Journals (Sweden)

    Haitham Ahmed Yacoub

    2015-04-01

    Full Text Available Host Defense Peptides (HDPs are small cationic peptides found in several organisms. They play a vital role in innate immunity response and immunomodulatory stimulation. This investigation was designed to study the antimicrobial activities of β-defensin peptide-4 (sAvBD-4 and 10 (sAvBD-4 derived from chickens against pathogenic organisms including bacteria and fungi. Ten bacterial strains and three fungal species were used in investigation. The results showed that the sAvBD-10 displayed a higher bactericidal potency against all the tested bacterial strains than that of sAvBD-4. The exhibited bactericidal activity was significant against almost the different bacterial strains at different peptide concentrations except for that of P. aeruginosa and Str. bovis strains where a moderate effect was noted. Both peptides were effective in the inactivation of fungal species tested yielding a killing rate of up to 95%. The results revealed that the synthetic peptides were resistant to salt at a concentration of 50mM NaCl. However, they lost antimicrobial potency when applied in the presence of high salt concentrations. Based on blood hemolysis studies, a little hemolytic effect was showed in the case of both peptides even when applied at high concentrations. The data obtained from this study indicated that synthetic avian peptides exhibit strong antibacterial and antifungal activity. In conclusion, future work and research should be tailored to a better understanding of the mechanisms of action of those peptides and their potential use in the pharmaceutical industry to help reduce the incidence and impact of infectious agent and be marketed as a naturally occurring antibiotic.

  18. Antimicrobial activities of chicken β-defensin (4 and 10) peptides against pathogenic bacteria and fungi.

    Science.gov (United States)

    Yacoub, Haitham A; Elazzazy, Ahmed M; Abuzinadah, Osama A H; Al-Hejin, Ahmed M; Mahmoud, Maged M; Harakeh, Steve M

    2015-01-01

    Host Defense Peptides (HDPs) are small cationic peptides found in several organisms. They play a vital role in innate immunity response and immunomodulatory stimulation. This investigation was designed to study the antimicrobial activities of β-defensin peptide-4 (sAvBD-4) and 10 (sAvBD-4) derived from chickens against pathogenic organisms including bacteria and fungi. Ten bacterial strains and three fungal species were used in investigation. The results showed that the sAvBD-10 displayed a higher bactericidal potency against all the tested bacterial strains than that of sAvBD-4. The exhibited bactericidal activity was significant against almost the different bacterial strains at different peptide concentrations except for that of Pseudomonas aeruginosa (P. aeruginosa) and Streptococcus bovis (Str. bovis) strains where a moderate effect was noted. Both peptides were effective in the inactivation of fungal species tested yielding a killing rate of up to 95%. The results revealed that the synthetic peptides were resistant to salt at a concentration of 50 mM NaCl. However, they lost antimicrobial potency when applied in the presence of high salt concentrations. Based on blood hemolysis studies, a little hemolytic effect was showed in the case of both peptides even when applied at high concentrations. The data obtained from this study indicated that synthetic avian peptides exhibit strong antibacterial and antifungal activity. In conclusion, future work and research should be tailored to a better understanding of the mechanisms of action of those peptides and their potential use in the pharmaceutical industry to help reduce the incidence and impact of infectious agent and be marketed as a naturally occurring antibiotic.

  19. Primary study on the resistance to bacterial blight (X. oryzae) in Cecropin B gene transgenic rices

    Institute of Scientific and Technical Information of China (English)

    HUAZhihua; HUANGDanian; XUERui; WANGXiaoling; GAOZhenya

    1998-01-01

    Bacterial blight (BB) is one of the major diseases to rice. Antibacterial Cecropin B gene has been cloned and transformed into rice. We studied the resistance to bacterial blight in Cecropin B gene tronsgenic rices.

  20. Bacterial flora and antimicrobial resistance in raw frozen cultured seafood imported to Denmark.

    Science.gov (United States)

    Noor Uddin, Gazi M; Larsen, Marianne Halberg; Guardabassi, Luca; Dalsgaard, Anders

    2013-03-01

    Intensified aquaculture includes the use of antimicrobials for disease control. In contrast to the situation in livestock, Escherichia coli and enterococci are not part of the normal gastrointestinal flora of fish and shrimp and therefore not suitable indicators of antimicrobial resistance in seafood. In this study, the diversity and phenotypic characteristics of the bacterial flora in raw frozen cultured and wild-caught shrimp and fish were evaluated to identify potential indicators of antimicrobial resistance. The bacterial flora cultured on various agar media at different temperatures yielded total viable counts of 4.0 × 10(4) to 3.0 × 10(5) CFU g(-1). Bacterial diversity was indicated by 16S rRNA sequence analysis of 84 isolates representing different colony types; 24 genera and 51 species were identified. Pseudomonas spp. (23% of isolates), Psychrobacter spp. (17%), Serratia spp. (13%), Exiguobacterium spp. (7%), Staphylococcus spp. (6%), and Micrococcus spp. (6%) dominated. Disk susceptibility testing of 39 bacterial isolates to 11 antimicrobials revealed resistance to ampicillin, amoxicillin-clavulanic acid, erythromycin, and third generation cephalosporins. Resistance to third generation cephalosporins was found in Pseudomonas, a genus naturally resistant to most β-lactam antibiotics, and in Staphylococcus hominis. Half of the isolates were susceptible to all antimicrobials tested. Results indicate that identification of a single bacterial resistance indicator naturally present in seafood at point of harvest is unlikely. The bacterial flora found likely represents a processing rather than a raw fish flora because of repeated exposure of raw material to water during processing. Methods and appropriate indicators, such as quantitative PCR of resistance genes, are needed to determine how antimicrobials used in aquaculture affect resistance of bacteria in retailed products.

  1. Resistance trends among clinical isolates in China reported from CHINET surveillance of bacterial resistance, 2005-2014.

    Science.gov (United States)

    Hu, F-P; Guo, Y; Zhu, D-M; Wang, F; Jiang, X-F; Xu, Y-C; Zhang, X-J; Zhang, C-X; Ji, P; Xie, Y; Kang, M; Wang, C-Q; Wang, A-M; Xu, Y-H; Shen, J-L; Sun, Z-Y; Chen, Z-J; Ni, Y-X; Sun, J-Y; Chu, Y-Z; Tian, S-F; Hu, Z-D; Li, J; Yu, Y-S; Lin, J; Shan, B; Du, Y; Han, Y; Guo, S; Wei, L-H; Wu, L; Zhang, H; Kong, J; Hu, Y-J; Ai, X-M; Zhuo, C; Su, D-H; Yang, Q; Jia, B; Huang, W

    2016-03-01

    With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22,774 and 84,572 annually. Rates of extended-spectrum β-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.

  2. Diversity of Dominant Bacterial Taxa in Activated Sludge Promotes Functional Resistance following Toxic Shock Loading

    KAUST Repository

    Saikaly, Pascal

    2010-12-14

    Examining the relationship between biodiversity and functional stability (resistance and resilience) of activated sludge bacterial communities following disturbance is an important first step towards developing strategies for the design of robust biological wastewater treatment systems. This study investigates the relationship between functional resistance and biodiversity of dominant bacterial taxa by subjecting activated sludge samples, with different levels of biodiversity, to toxic shock loading with cupric sulfate (Cu[II]), 3,5-dichlorophenol (3,5-DCP), or 4-nitrophenol (4-NP). Respirometric batch experiments were performed to determine the functional resistance of activated sludge bacterial community to the three toxicants. Functional resistance was estimated as the 30 min IC50 or the concentration of toxicant that results in a 50% reduction in oxygen utilization rate compared to a referential state represented by a control receiving no toxicant. Biodiversity of dominant bacterial taxa was assessed using polymerase chain reaction-terminal restriction fragment length polymorphism (PCR-T-RFLP) targeting the 16S ribosomal RNA (16S rRNA) gene. Statistical analysis of 30 min IC50 values and PCR-T-RFLP data showed a significant positive correlation (P<0.05) between functional resistance and microbial diversity for each of the three toxicants tested. To our knowledge, this is the first study showing a positive correlation between biodiversity of dominant bacterial taxa in activated sludge and functional resistance. In this system, activated sludge bacterial communities with higher biodiversity are functionally more resistant to disturbance caused by toxic shock loading. © 2010 Springer Science+Business Media, LLC.

  3. [Resistance acquisition via the bacterial SOS response: the inducive role of antibiotics].

    Science.gov (United States)

    Da Re, Sandra; Ploy, Marie-Cécile

    2012-02-01

    After the euphoria of the antibiotic discovery and their tremendous action on bacterial infections outcomes, arrives a period of fear with the continuous emergence of bacteria that are resistant to almost all antibiotic treatments. It is becoming essential to better understand antibiotic resistance mechanisms to find new approaches to prevent the worldwide problem of multiresistance. The role of antibiotics on the direct induction of resistance acquisition is known. Recent studies have shown that some antibiotics, by inducing the bacterial SOS response, global repair response after DNA damages, are involved on a broader level in the induction, acquisition and dissemination of resistances in bacteria. We discuss here the role of antibiotics in resistance acquisition via the SOS response through several examples and the interest of identifying the SOS response regulators as the future targets of new families of antimicrobial molecules.

  4. Absence of bacterial resistance to medical-grade manuka honey

    OpenAIRE

    2010-01-01

    Abstract Clinical use of honey in the topical treatment of wounds has increased in Europe and North America since licensed wound care products became available in 2004 and 2007, respectively. Honey-resistant bacteria have not been isolated from wounds, but there is a need to investigate whether honey has the potential to select for honey resistance. Two cultures of bacteria from reference collections (Staphylococcus aureus NCTC 10017 and Pseudomonas aeruginosa ATCC 27853) and four ...

  5. Mechanisms and Biological Costs of Bacterial Resistance to Antimicrobial Peptides

    OpenAIRE

    Lofton Tomenius, Hava

    2016-01-01

    The global increasing problem of antibiotic resistance necessarily drives the pursuit and discovery of new antimicrobial agents. Antimicrobial peptides (AMPs) initially seemed like promising new drug candidates. Already members of the innate immune system, it was assumed that they would be bioactive and non-toxic. Their common trait for fundamental, non-specific mode of action also seemed likely to reduce resistance development. In this thesis, we demonstrate the ease with which two species o...

  6. Development of resistant tomato population with bacterial canker resistance genes from interspecific hybrids by the support of embryo rescue

    Directory of Open Access Journals (Sweden)

    Aylin KABAŞ

    2016-06-01

    Full Text Available Bacterial canker is one of the most important diseases causing economic yield loss in tomato production areas in the world. The best way to control for this disease is to use resistant varieties. However, there are few studies on variety breeding studies of this disease compared with other disease resistant breeding studies. In this study we aimed to improve inbred lines carrying bacterial canker resistance genes to use in the breeding of resistant varieties. Susceptible inbred line AK1 (S. esculentum and resistant LA2157 (S. peruvianum were crossed. Embryo rescue and ovule culture techniques were applied in 30 fruits to get F1 hybrids. Rescued embryos and immature ovules were cultured in petri dishes containing solidified MS medium without hormone. 30 healty embryos were excised and cultured from 30 fruits 27-61 day old (1 embryo fruit-1 in embryo rescue method. The two surviving plants from acclimatization were transferred to the greenhouse to get their BC1 progenies. Resistance tests were performed according to the stem inoculation method in the BC1 and BC2 progenies. The mixture of 14 aggressive Turkish Cmm strains were used to confirm the resistance. The plants were valued by 0-4 scale. Plants with 0 and 1 scale values were used to obtain next progenies. A total of 80 BC3 resistant progenies were transferred to our variety breeding programme.

  7. Using experimental evolution to explore natural patterns between bacterial motility and resistance to bacteriophages.

    Science.gov (United States)

    Koskella, Britt; Taylor, Tiffany B; Bates, Jennifer; Buckling, Angus

    2011-11-01

    Resistance of bacteria to phages may be gained by alteration of surface proteins to which phages bind, a mechanism that is likely to be costly as these molecules typically have critical functions such as movement or nutrient uptake. To address this potential trade-off, we combine a systematic study of natural bacteria and phage populations with an experimental evolution approach. We compare motility, growth rate and susceptibility to local phages for 80 bacteria isolated from horse chestnut leaves and, contrary to expectation, find no negative association between resistance to phages and bacterial motility or growth rate. However, because correlational patterns (and their absence) are open to numerous interpretations, we test for any causal association between resistance to phages and bacterial motility using experimental evolution of a subset of bacteria in both the presence and absence of naturally associated phages. Again, we find no clear link between the acquisition of resistance and bacterial motility, suggesting that for these natural bacterial populations, phage-mediated selection is unlikely to shape bacterial motility, a key fitness trait for many bacteria in the phyllosphere. The agreement between the observed natural pattern and the experimental evolution results presented here demonstrates the power of this combined approach for testing evolutionary trade-offs.

  8. Bacterial load of fresh vegetables and their resistance to the currently used antibiotics in Saudi Arabia.

    Science.gov (United States)

    Hassan, Sabry A; Altalhi, Abdullah D; Gherbawy, Youssuf A; El-Deeb, Bahig A

    2011-09-01

    This study was carried out to describe the bacterial load and the occurrence of some disease-causing enteric bacteria on raw vegetables sold in Saudi markets. The study further aimed to analyze antibiotic resistance rates, production of extended-spectrum beta lactamase, and plasmid carriage among bacterial population of raw vegetables. Results revealed that none of them contained Bacillus cereus, Salmonella, and Escherichia coli O157:H7. However, Staphylococcus aureus and Shigella were detected in 11.8% and 4.4% of the samples, respectively. The bacterial loads ranged from 3 to 8 log(10) CFUg(-1) for aerobic bacteria and 1 to 4 log(10) CFUg(-1) for coliforms as well as Enterobacteriaceae. The isolates exhibited resistance in decreasing order for ampicillin (76.5%), cephalothin (69.5%), trimethoprime-sulfamethoxazole (36.7%), aminoglycosides (21.9%), tetracycline (17.2%), fluoroquinolones (17.2%), amoxycillin-clavulanic acid (13.3%), and chloramphenicol (7.8%). Maximum resistance to extended-spectrum beta-lactam antibiotics occurred in 14.8% of isolates and the production of extended-spectrum beta-lactamase was achieved by 2.3% of isolates. Multiple resistances to four or more antimicrobial agents along with plasmid with varied sizes were documented. These investigations indicate the occurrence of antibiotic resistance and plasmid carriage among bacterial isolates populating raw vegetables.

  9. Induced bacterial cross-resistance toward host antimicrobial peptides: a worrying phenomenon

    Directory of Open Access Journals (Sweden)

    Osmel eFleitas

    2016-03-01

    Full Text Available Bacterial resistance to conventional antibiotics has reached alarming levels, threatening to return to the pre-antibiotic era. Therefore, the search for new antimicrobial compounds that overcome the resistance phenomenon has become a priority. Antimicrobial peptides (AMPs appear as one of the most promising antibiotic medicines. However, in recent years several AMP-resistance mechanisms have been described. Moreover, the AMP-resistance phenomenon has become more complex due to its association with cross-resistance toward AMP effectors of the host innate immune system. In this context, the use of AMPs as a therapeutic option could be potentially hazardous, since bacteria could develop resistance toward our innate immune system. Here we review the findings of major studies that deal with the AMP cross-resistance phenomenon.

  10. Interfamily transfer of a plant pattern-recognition receptor confers broad-spectrum bacterial resistance.

    Science.gov (United States)

    Lacombe, Séverine; Rougon-Cardoso, Alejandra; Sherwood, Emma; Peeters, Nemo; Dahlbeck, Douglas; van Esse, H Peter; Smoker, Matthew; Rallapalli, Ghanasyam; Thomma, Bart P H J; Staskawicz, Brian; Jones, Jonathan D G; Zipfel, Cyril

    2010-04-01

    Plant diseases cause massive losses in agriculture. Increasing the natural defenses of plants may reduce the impact of phytopathogens on agricultural productivity. Pattern-recognition receptors (PRRs) detect microbes by recognizing conserved pathogen-associated molecular patterns (PAMPs). Although the overall importance of PAMP-triggered immunity for plant defense is established, it has not been used to confer disease resistance in crops. We report that activity of a PRR is retained after its transfer between two plant families. Expression of EFR (ref. 4), a PRR from the cruciferous plant Arabidopsis thaliana, confers responsiveness to bacterial elongation factor Tu in the solanaceous plants Nicotiana benthamiana and tomato (Solanum lycopersicum), making them more resistant to a range of phytopathogenic bacteria from different genera. Our results in controlled laboratory conditions suggest that heterologous expression of PAMP recognition systems could be used to engineer broad-spectrum disease resistance to important bacterial pathogens, potentially enabling more durable and sustainable resistance in the field.

  11. Quantitative Trait Loci Mapping for Bacterial Blight Resistance in Rice Using Bulked Segregant Analysis

    Directory of Open Access Journals (Sweden)

    Xueying Han

    2014-07-01

    Full Text Available Oryza meyeriana is highly resistant to rice bacterial blight (BB and this resistance trait has been transferred to cultivated rice (O. sativa using asymmetric somatic hybridization. However, no resistance genes have yet been cloned. In the present study, a progeny of the somatic hybridization with high BB resistance was crossed with a rice cultivar with high BB susceptibility to develop an F2 population. Using bulked segregant analysis (BSA, 17 polymorphic markers that were linked to rice BB resistance were obtained through scanning a total of 186 simple sequence repeats (SSR and sequence-tagged site (STS markers, evenly distributed on 12 chromosomes. A genetic linkage map was then constructed based on the 17 linkage markers and the F2 segregating population, which was followed by mapping for quantitative trait loci (QTLs for BB resistance. Three QTLs were identified on chromosomes 1, 3 and 5, respectively, and the alleles of the resistant parent at any of the QTLs increased BB resistance. All of the three QTLs had a strong effect on resistance, explaining about 21.5%, 12.3% and 39.2% of the resistance variance, respectively. These QTLs were different from the loci of the BB resistance genes that have been identified in previous studies. The QTLs mapped in this work will facilitate the isolation of novel BB resistance genes and their utilization in rice resistance breeding.

  12. Increase in Antibiotic-Resistant Gram-Negative Bacterial Infections in Febrile Neutropenic Children

    OpenAIRE

    Lee, Joon Hee; Kim, Seul-Ki; Kim, Seong Koo; Han, Seung Beom; Lee, Jae Wook; Lee, Dong-Gun; Chung, Nack-Gyun; Cho, Bin; Jeong, Dae Chul; Kang, Jin Han; Kim, Hack-Ki

    2016-01-01

    Background The incidence of bacteremia caused by Gram-negative bacteria has increased recently in febrile neutropenic patients with the increase of antibiotic-resistant Gram-negative bacterial infections. This study aimed to identify the distribution of causative bacteria and the proportion of antibiotic-resistant bacteria in bacteremia diagnosed in febrile neutropenic children. Materials and Methods The medical records of febrile neutropenic children diagnosed with bacteremia between 2010 an...

  13. Fluoroquinolone-metal complexes: a route to counteract bacterial resistance?

    Science.gov (United States)

    Feio, Maria J; Sousa, Isabel; Ferreira, Mariana; Cunha-Silva, Luís; Saraiva, Raúl G; Queirós, Carla; Alexandre, José G; Claro, Vasco; Mendes, Adélia; Ortiz, Rosa; Lopes, Sandra; Amaral, Ana Luísa; Lino, João; Fernandes, Patrícia; Silva, Ana João; Moutinho, Lisete; de Castro, Baltazar; Pereira, Eulália; Perelló, Lourdes; Gameiro, Paula

    2014-09-01

    Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH7.4) only copper(II):FQ:phen ternary complexes are stable. Hence, these complexes were synthesised and characterised by means of UV-visible and IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. In these complexes, the FQ acts as a bidentate ligand that coordinates the metal cation through the carbonyl and carboxyl oxygen atoms and phen coordinates through two N-atoms forming the equatorial plane of a distorted square-pyramidal geometry. The fifth position of the penta-coordinated Cu(II) centre is generally occupied axially by an oxygen atom from a water molecule or from a nitrate ion. Minimum inhibitory concentration (MIC) determinations of the complexes and comparison with free FQ in various E. coli strains indicate that the Cu-complexes are as efficient antimicrobials as the free antibiotic. Moreover, results strongly suggest that the cell intake route of both species is different supporting, therefore, the complexes' suitability as candidates for further biological testing in FQ-resistant microorganisms.

  14. Antifungal Agents: Mode of Action, Mechanisms of Resistance, and Correlation of These Mechanisms with Bacterial Resistance

    OpenAIRE

    Ghannoum, Mahmoud A.; Rice, Louis B

    1999-01-01

    The increased use of antibacterial and antifungal agents in recent years has resulted in the development of resistance to these drugs. The significant clinical implication of resistance has led to heightened interest in the study of antimicrobial resistance from different angles. Areas addressed include mechanisms underlying this resistance, improved methods to detect resistance when it occurs, alternate options for the treatment of infections caused by resistant organisms, and strategies to ...

  15. [Ecology and mechanisms of bacterial resistance to antibiotics in peritonitis].

    Science.gov (United States)

    Edern, Anita; Fines-Guyon, Marguerite; Castrale, Cindy; Ficheux, Maxence; Ryckelynck, Jean-Philippe; Lobbedez, Thierry

    2012-11-01

    Peritonitis remains a common complication of peritoneal dialysis. The aim of our study is to describe the mechanisms of antibiotic resistance in bacteria isolated during peritonitis in peritoneal dialysis, to determine whether antibiotic therapy proposed by the International Society for Peritoneal Dialysis (ISPD) is adapted to the mechanisms of resistance. All causative microorganisms of peritonitis, isolated in 106 dialysis patients and reported 170 episodes of peritonitis, during the study period (01/01/2005 to 31/12/2010) were reviewed. According to the usual classification, twelve groups of microorganism were created. An interpretive reading of antibiograms was performed in each group to identify resistance phenotypes. The species most frequently isolated are coagulase-negative staphylococci (n=73) of which 46 had PBP2a (penicillin-binding protein). Many Enterobacteriaceae were also isolated (n=45), they are susceptible to third generation cephalosporins with the exception of Enterobacteriaceae producing an extended spectrum β-lactamase (ESBL) or a cephalosporinase. Except for staphylococci, probabilistic antibiotic therapy recommended by the ISPD to treat peritonitis is effective. Indeed, many staphylococci producing a PBP2a, a first-generation cephalosporin cannot be administered in all cases. It is therefore necessary to identify patients with a strain of staphylococcus producing a PBP2a, it must be treated by vancomycin.

  16. A genome-wide screen identifies a single β-defensin gene cluster in the chicken: implications for the origin and evolution of mammalian defensins

    Directory of Open Access Journals (Sweden)

    Xiao Yanjing

    2004-08-01

    Full Text Available Abstract Background Defensins comprise a large family of cationic antimicrobial peptides that are characterized by the presence of a conserved cysteine-rich defensin motif. Based on the spacing pattern of cysteines, these defensins are broadly divided into five groups, namely plant, invertebrate, α-, β-, and θ-defensins, with the last three groups being mostly found in mammalian species. However, the evolutionary relationships among these five groups of defensins remain controversial. Results Following a comprehensive screen, here we report that the chicken genome encodes a total of 13 different β-defensins but with no other groups of defensins being discovered. These chicken β-defensin genes, designated as Gallinacin 1–13, are clustered densely within a 86-Kb distance on the chromosome 3q3.5-q3.7. The deduced peptides vary from 63 to 104 amino acid residues in length sharing the characteristic defensin motif. Based on the tissue expression pattern, 13 β-defensin genes can be divided into two subgroups with Gallinacin 1–7 being predominantly expressed in bone marrow and the respiratory tract and the remaining genes being restricted to liver and the urogenital tract. Comparative analysis of the defensin clusters among chicken, mouse, and human suggested that vertebrate defensins have evolved from a single β-defensin-like gene, which has undergone rapid duplication, diversification, and translocation in various vertebrate lineages during evolution. Conclusions We conclude that the chicken genome encodes only β-defensin sequences and that all mammalian defensins are evolved from a common β-defensin-like ancestor. The α-defensins arose from β-defensins by gene duplication, which may have occurred after the divergence of mammals from other vertebrates, and θ-defensins have arisen from α-defensins specific to the primate lineage. Further analysis of these defensins in different vertebrate lineages will shed light on the mechanisms of

  17. [Bacterial efflux pumps - their role in antibiotic resistance and potential inhibitors].

    Science.gov (United States)

    Hricová, Kristýna; Kolář, Milan

    2014-12-01

    Efflux pumps capable of actively draining antibiotic agents from bacterial cells may be considered one of potential mechanisms of the development of antimicrobial resistance. The most important group of efflux pumps capable of removing several types of antibiotics include RND (resistance - nodulation - division) pumps. These are three proteins that cross the bacterial cell wall, allowing direct expulsion of the agent out from the bacterial cell. The most investigated efflux pumps are the AcrAB-TolC system in Escherichia coli and the MexAB-OprM system in Pseudomonas aeruginosa. Moreover, efflux pumps are able to export other than antibacterial agents such as disinfectants, thus decreasing their effectiveness. One potential approach to inactivation of an efflux pump is to use the so-called efflux pump inhibitors (EPIs). Potential inhibitors tested in vitro involve, for example, phenylalanyl-arginyl-b-naphthylamide (PAbN), carbonyl cyanide m-chlorophenylhydrazone (CCCP) or agents of the phenothiazine class.

  18. Bacterial multidrug resistance mediated by a homologue of the human multidrug transporter P-glycoprotein

    NARCIS (Netherlands)

    Konings, WN; Poelarends, GJ

    2002-01-01

    Most ATP-binding cassette (ABC) multidrug transporters known to date are of eukaryotic origin, such as the P-glycoproteins (Pgps) and multidrug resistance-associated proteins (MRPs). Only one well-characterized ABC multidrug transporter, LmrA, is of bacterial origin. On the basis of its structural a

  19. Epidemiology and antibiotic resistance of bacterial meningitis in Dapaong, northern Togo

    Institute of Scientific and Technical Information of China (English)

    Simplice D Karou; Abago Balaka; Mitiname Bamok; Damhan Tchelougou; Malki Assih; Kokou Anani; Kodjo Agbonoko; Jacques Simpore; Comlan de Souza

    2012-01-01

    Objective:To assess the seasonality of the bacterial meningitis and the antibiotic resistance of incriminated bacteria over the last three years in the northern Togo. Methods: From January 2007 to January 2010, 533 cerebrospinal fluids (CSF) samples were collected from patients suspected of meningitis in the Regional Hospital of Dapaong (northern Togo). After microscopic examination, samples were cultured for bacterial identification and antibiotic susceptibility. Results:The study included 533 patients (306 male and 227 female) aged from 1 day to 55 years [average age (13.00±2.07) years]. Bacterial isolation and identification were attempted for 254/533 (47.65%) samples. The bacterial species identified were:Neisseria meningitidis A (N. meningitidis A) (58.27%), Neisseria meningitidis W135 (N. meningitidis W135) (7.09%), Streptococcus pneumoniae (S. pneumoniae) (26.77%), Haemophilus influenza B (H. influenza B) (6.30%) and Enterobacteriaceae (1.57%). The results indicated that bacterial meningitis occur from November to May with a peak in February for H. influenzae and S. pneumoniae and March for Neisseriaceae. The distribution of positive CSF with regards to the age showed that subjects between 6 and 12 years followed by subjects of 0 to 5 years were most affected with respective frequencies of 67.82% and 56.52% (P20%for both bacterial strains), macrolides (resistance rate> 30%for H. influenzae) quinolones (resistance rate>15%for H. influenzae and N. meningitidis W135). Over three years, the prevalence of S. pneumoniae significantly increased from 8.48%to 73.33%(P<0.001), while the changes in the prevalence of H. influenzae B were not statistically significant: 4.24%, vs. 8.89%, (P= 0.233). Conclusions:Our results indicate that data in African countries differ depending on geographical location in relation to the African meningitis belt. This underlines the importance of epidemiological surveillance of bacterial meningitis.

  20. Bacterial infections in Lilongwe, Malawi: aetiology and antibiotic resistance

    Directory of Open Access Journals (Sweden)

    Makoka Mwai H

    2012-03-01

    Full Text Available Abstract Background Life-threatening infections present major challenges for health systems in Malawi and the developing world because routine microbiologic culture and sensitivity testing are not performed due to lack of capacity. Use of empirical antimicrobial therapy without regular microbiologic surveillance is unable to provide adequate treatment in the face of emerging antimicrobial resistance. This study was conducted to determine antimicrobial susceptibility patterns in order to inform treatment choices and generate hospital-wide baseline data. Methods Culture and susceptibility testing was performed on various specimens from patients presenting with possible infectious diseases at Kamuzu Central Hospital, Lilongwe, Malawi. Results Between July 2006 and December 2007 3104 specimens from 2458 patients were evaluated, with 60.1% from the adult medical service. Common presentations were sepsis, meningitis, pneumonia and abscess. An etiologic agent was detected in 13% of patients. The most common organisms detected from blood cultures were Staphylococcus aureus, Escherichia coli, Salmonella species and Streptococcus pneumoniae, whereas Streptococcus pneumoniae and Cryptococcus neoformans were most frequently detected from cerebrospinal fluid. Haemophilus influenzae was rarely isolated. Resistance to commonly used antibiotics was observed in up to 80% of the isolates while antibiotics that were not commonly in use maintained susceptibility. Conclusions There is widespread resistance to almost all of the antibiotics that are empirically used in Malawi. Antibiotics that have not been widely introduced in Malawi show better laboratory performance. Choices for empirical therapy in Malawi should be revised accordingly. A microbiologic surveillance system should be established and prudent use of antimicrobials promoted to improve patient care.

  1. Ionizing radiation resistant bacteria; Des bacteries resistantes aux rayonnements ionisants

    Energy Technology Data Exchange (ETDEWEB)

    Libert, M. [CEA/Cadarache, Dept. d' Entreposage et de Stockage des Dechets (DESD), 13 - Saint-Paul-lez-Durance (France)

    2000-07-01

    The living being are not equal face to ionizing radiations. The palm of resistance goes to some bacteria. The champion at any category, the Deinococcus radiodurans, tolerates radiations doses whom one thousandth would kill a man. Two reasons to this fact: after irradiation, the DNA replication is stopped in order that the bacteria can use a repair process called multiple recombination. It cuts intact pieces of a injured chromosome and recombines them with other intact pieces, reconstituting a functional chromosome. It has also an ability to endure the extended action of oxygen, large source of damages for DNA. (N.C.)

  2. Pyramiding blast, bacterial blight and brown planthopper resistance genes in rice restorer lines

    Institute of Scientific and Technical Information of China (English)

    JI Zhi-juan; Yang Shu-dong; ZENG Yu-xiang; LIANG Yan; YANG Chang-deng; QIAN Qian

    2016-01-01

    Rice blast, bacterial blight (BB) and brown planthopper (BPH) are the three main pests of rice. This study investigated pyr-amiding genes resistant to blast, BB and BPH to develop restorer lines. Ten new lines with blast, BB and/or BPH resistance genes were developed using marker-assisted selection (MAS) technique and agronomic trait selection (ATS) method. Only HR13 with resistance genes to blast, BB and BPH was obtained. In addition to blast and BB resistance, four lines (HR39, HR41, HR42, HR43) demonstrated moderate resistance to BPH, but MAS for BPH resistance genes were not conducted in developing these four lines. These data suggested that there were unknown elite BPH resistance genes in the Zhongzu 14 donor parent. A more effective defense was demonstrated in the lines withPi1 andPi2 genes although the weather in 2012 was favorable to disease incidence. Blast resistance of the lines with a single resistance gene,Pita, was easily inlfuenced by the weather. Overal, the information obtained through pyramiding multiple resistance genes on developing the restorer lines is helpful for rice resistance breeding.

  3. The repertoire of equine intestinal α-defensins

    OpenAIRE

    Tetens Jens; Paul Sven; Bruhn Oliver; Thaller Georg

    2009-01-01

    Abstract Background Defensins represent an important class of antimicrobial peptides. These effector molecules of the innate immune system act as endogenous antibiotics to protect the organism against infections with pathogenic microorganisms. Mammalian defensins are classified into three distinct sub-families (α-, β- and θ-defensins) according to their specific intramolecular disulfide-bond pattern. The peptides exhibit an antimicrobial activity against a broad spectrum of microorganisms inc...

  4. Mutations in the bacterial ribosomal protein l3 and their association with antibiotic resistance

    DEFF Research Database (Denmark)

    Klitgaard, Rasmus N; Ntokou, Eleni; Nørgaard, Katrine

    2015-01-01

    Different groups of antibiotics bind to the peptidyl transferase center (PTC) in the large subunit of the bacterial ribosome. Resistance to these groups of antibiotics has often been linked with mutations or methylations of the 23S rRNA. In recent years, there has been a rise in the number...... of studies where mutations have been found in the ribosomal protein L3 in bacterial strains resistant to PTC-targeting antibiotics but there is often no evidence that these mutations actually confer antibiotic resistance. In this study, a plasmid exchange system was used to replace plasmid-carried wild...... background. Ten plasmid-carried mutated L3 genes were constructed, and their effect on growth and antibiotic susceptibility was investigated. Additionally, computational modeling of the impact of L3 mutations in E. coli was used to assess changes in 50S structure and antibiotic binding. All mutations...

  5. Antibiotic resistance among cultured bacterial isolates from bioethanol fermentation facilities across the United States.

    Science.gov (United States)

    Murphree, Colin A; Heist, E Patrick; Moe, Luke A

    2014-09-01

    Bacterial contamination of fuel ethanol fermentations by lactic acid bacteria (LAB) can have crippling effects on bioethanol production. Producers have had success controlling bacterial growth through prophylactic addition of antibiotics to fermentors, yet concerns have arisen about antibiotic resistance among the LAB. Here, we report on mechanisms used by 32 LAB isolates from eight different US bioethanol facilities to persist under conditions of antibiotic stress. Minimum inhibitory concentration assays with penicillin, erythromycin, and virginiamycin revealed broad resistance to each of the antibiotics as well as high levels of resistance to individual antibiotics. Phenotypic assays revealed that antibiotic inactivation mechanisms contributed to the high levels of individual resistances among the isolates, especially to erythromycin and virginiamycin, yet none of the isolates appeared to use a β-lactamase. Biofilm formation was noted among the majority of the isolates and may contribute to persistence under low levels of antibiotics. Nearly all of the isolates carried at least one canonical antibiotic resistance gene and many carried more than one. The erythromycin ribosomal methyltransferase (erm) gene class was found in 19 of 32 isolates, yet a number of these isolates exhibit little to no resistance to erythromycin. The erm genes were present in 15 isolates that encoded more than one antibiotic resistance mechanism, suggestive of potential genetic linkages.

  6. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

    Energy Technology Data Exchange (ETDEWEB)

    Hoelzel, Christina S., E-mail: Christina.Hoelzel@wzw.tum.de [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mueller, Christa [Institute for Agroecology, Organic Farming and Soil Protection, Bavarian State Research Center for Agriculture (LfL), Lange Point 12, 85354 Freising (Germany); Harms, Katrin S. [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mikolajewski, Sabine [Department for Quality Assurance and Analytics, Bavarian State Research Center for Agriculture (LfL), Lange Point 4, 85354 Freising (Germany); Schaefer, Stefanie; Schwaiger, Karin; Bauer, Johann [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany)

    2012-02-15

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  7. Cultivable bacterial microbiota of northern bobwhite (Colinus virginianus: a new reservoir of antimicrobial resistance?

    Directory of Open Access Journals (Sweden)

    Hongwen Su

    Full Text Available The northern bobwhite (Colinus virginianus is an ecologically and economically important avian species. At the present time, little is known about the microbial communities associated with these birds. As the first step to create a quail microbiology knowledge base, the current study conducted an inventory of cultivable quail tracheal, crop, cecal, and cloacal microbiota and associated antimicrobial resistance using a combined bacteriology and DNA sequencing approach. A total of 414 morphologically unique bacterial colonies were selected from nonselective aerobic and anaerobic cultures, as well as selective and enrichment cultures. Analysis of the first 500-bp 16S rRNA gene sequences in conjunction with biochemical identifications revealed 190 non-redundant species-level taxonomic units, representing 160 known bacterial species and 30 novel species. The bacterial species were classified into 4 phyla, 14 orders, 37 families, and 59 or more genera. Firmicutes was the most commonly encountered phylum (57% followed by Actinobacteria (24%, Proteobacteria (17% and Bacteroidetes (0.02%. Extensive diversity in the species composition of quail microbiota was observed among individual birds and anatomical locations. Quail microbiota harbored several opportunistic pathogens, such as E. coli and Ps. aeruginosa, as well as human commensal organisms, including Neisseria species. Phenotypic characterization of selected bacterial species demonstrated a high prevalence of resistance to the following classes of antimicrobials: phenicol, macrolide, lincosamide, quinolone, and sulphate. Data from the current investigation warrant further investigation on the source, transmission, pathology, and control of antimicrobial resistance in wild quail populations.

  8. Cultivable bacterial microbiota of northern bobwhite (Colinus virginianus): a new reservoir of antimicrobial resistance?

    Science.gov (United States)

    Su, Hongwen; McKelvey, Jessica; Rollins, Dale; Zhang, Michael; Brightsmith, Donald J; Derr, James; Zhang, Shuping

    2014-01-01

    The northern bobwhite (Colinus virginianus) is an ecologically and economically important avian species. At the present time, little is known about the microbial communities associated with these birds. As the first step to create a quail microbiology knowledge base, the current study conducted an inventory of cultivable quail tracheal, crop, cecal, and cloacal microbiota and associated antimicrobial resistance using a combined bacteriology and DNA sequencing approach. A total of 414 morphologically unique bacterial colonies were selected from nonselective aerobic and anaerobic cultures, as well as selective and enrichment cultures. Analysis of the first 500-bp 16S rRNA gene sequences in conjunction with biochemical identifications revealed 190 non-redundant species-level taxonomic units, representing 160 known bacterial species and 30 novel species. The bacterial species were classified into 4 phyla, 14 orders, 37 families, and 59 or more genera. Firmicutes was the most commonly encountered phylum (57%) followed by Actinobacteria (24%), Proteobacteria (17%) and Bacteroidetes (0.02%). Extensive diversity in the species composition of quail microbiota was observed among individual birds and anatomical locations. Quail microbiota harbored several opportunistic pathogens, such as E. coli and Ps. aeruginosa, as well as human commensal organisms, including Neisseria species. Phenotypic characterization of selected bacterial species demonstrated a high prevalence of resistance to the following classes of antimicrobials: phenicol, macrolide, lincosamide, quinolone, and sulphate. Data from the current investigation warrant further investigation on the source, transmission, pathology, and control of antimicrobial resistance in wild quail populations.

  9. Cultivable Bacterial Microbiota of Northern Bobwhite (Colinus virginianus): A New Reservoir of Antimicrobial Resistance?

    Science.gov (United States)

    Su, Hongwen; McKelvey, Jessica; Rollins, Dale; Zhang, Michael; Brightsmith, Donald J.; Derr, James; Zhang, Shuping

    2014-01-01

    The northern bobwhite (Colinus virginianus) is an ecologically and economically important avian species. At the present time, little is known about the microbial communities associated with these birds. As the first step to create a quail microbiology knowledge base, the current study conducted an inventory of cultivable quail tracheal, crop, cecal, and cloacal microbiota and associated antimicrobial resistance using a combined bacteriology and DNA sequencing approach. A total of 414 morphologically unique bacterial colonies were selected from nonselective aerobic and anaerobic cultures, as well as selective and enrichment cultures. Analysis of the first 500-bp 16S rRNA gene sequences in conjunction with biochemical identifications revealed 190 non-redundant species-level taxonomic units, representing 160 known bacterial species and 30 novel species. The bacterial species were classified into 4 phyla, 14 orders, 37 families, and 59 or more genera. Firmicutes was the most commonly encountered phylum (57%) followed by Actinobacteria (24%), Proteobacteria (17%) and Bacteroidetes (0.02%). Extensive diversity in the species composition of quail microbiota was observed among individual birds and anatomical locations. Quail microbiota harbored several opportunistic pathogens, such as E. coli and Ps. aeruginosa, as well as human commensal organisms, including Neisseria species. Phenotypic characterization of selected bacterial species demonstrated a high prevalence of resistance to the following classes of antimicrobials: phenicol, macrolide, lincosamide, quinolone, and sulphate. Data from the current investigation warrant further investigation on the source, transmission, pathology, and control of antimicrobial resistance in wild quail populations. PMID:24937705

  10. Bacterial glyphosate resistance conferred by overexpression of an E. coli membrane efflux transporter.

    Science.gov (United States)

    Staub, Jeffrey M; Brand, Leslie; Tran, Minhtien; Kong, Yifei; Rogers, Stephen G

    2012-04-01

    Glyphosate herbicide-resistant crop plants, introduced commercially in 1994, now represent approximately 85% of the land area devoted to transgenic crops. Herbicide resistance in commercial glyphosate-resistant crops is due to expression of a variant form of a bacterial 5-enolpyruvylshikimate-3-phosphate synthase with a significantly decreased binding affinity for glyphosate at the target site of the enzyme. As a result of widespread and recurrent glyphosate use, often as the only herbicide used for weed management, increasing numbers of weedy species have evolved resistance to glyphosate. Weed resistance is most often due to changes in herbicide translocation patterns, presumed to be through the activity of an as yet unidentified membrane transporter in plants. To provide insight into glyphosate resistance mechanisms and identify a potential glyphosate transporter, we screened Escherichia coli genomic DNA for alternate sources of glyphosate resistance genes. Our search identified a single non-target gene that, when overexpressed in E. coli and Pseudomonas, confers high-level glyphosate resistance. The gene, yhhS, encodes a predicted membrane transporter of the major facilitator superfamily involved in drug efflux. We report here that an alternative mode of glyphosate resistance in E. coli is due to reduced accumulation of glyphosate in cells that overexpress this membrane transporter and discuss the implications for potential alternative resistance mechanisms in other organisms such as plants.

  11. Correlation models between environmental factors and bacterial resistance to antimony and copper.

    Directory of Open Access Journals (Sweden)

    Zunji Shi

    Full Text Available Antimony (Sb and copper (Cu are toxic heavy metals that are associated with a wide variety of minerals. Sb(III-oxidizing bacteria that convert the toxic Sb(III to the less toxic Sb(V are potentially useful for environmental Sb bioremediation. A total of 125 culturable Sb(III/Cu(II-resistant bacteria from 11 different types of mining soils were isolated. Four strains identified as Arthrobacter, Acinetobacter and Janibacter exhibited notably high minimum inhibitory concentrations (MICs for Sb(III (>10 mM,making them the most highly Sb(III-resistant bacteria to date. Thirty-six strains were able to oxidize Sb(III, including Pseudomonas-, Comamonas-, Acinetobacter-, Sphingopyxis-, Paracoccus- Aminobacter-, Arthrobacter-, Bacillus-, Janibacter- and Variovorax-like isolates. Canonical correspondence analysis (CCA revealed that the soil concentrations of Sb and Cu were the most obvious environmental factors affecting the culturable bacterial population structures. Stepwise linear regression was used to create two predictive models for the correlation between soil characteristics and the bacterial Sb(III or Cu(II resistance. The concentrations of Sb and Cu in the soil was the significant factors affecting the bacterial Sb(III resistance, whereas the concentrations of S and P in the soil greatly affected the bacterial Cu(II resistance. The two stepwise linear regression models that we derived are as follows: MIC(Sb(III=606.605+0.14533 x C(Sb+0.4128 x C(Cu and MIC((Cu(II=58.3844+0.02119 x C(S+0.00199 x CP [where the MIC(Sb(III and MIC(Cu(II represent the average bacterial MIC for the metal of each soil (μM, and the C(Sb, C(Cu, C(S and C(P represent concentrations for Sb, Cu, S and P (mg/kg in soil, respectively, p<0.01]. The stepwise linear regression models we developed suggest that metals as well as other soil physicochemical parameters can contribute to bacterial resistance to metals.

  12. Bacterial plasmid-mediated quinolone resistance genes in aquatic environments in China

    Science.gov (United States)

    Yan, Lei; Liu, Dan; Wang, Xin-Hua; Wang, Yunkun; Zhang, Bo; Wang, Mingyu; Xu, Hai

    2017-01-01

    Emerging antimicrobial resistance is a major threat to human’s health in the 21st century. Understanding and combating this issue requires a full and unbiased assessment of the current status on the prevalence of antimicrobial resistance genes and their correlation with each other and bacterial groups. In aquatic environments that are known reservoirs for antimicrobial resistance genes, we were able to reach this goal on plasmid-mediated quinolone resistance (PMQR) genes that lead to resistance to quinolones and possibly also to the co-emergence of resistance to β-lactams. Novel findings were made that qepA and aac-(6′)-Ib genes that were previously regarded as similarly abundant with qnr genes are now dominant among PMQR genes in aquatic environments. Further statistical analysis suggested that the correlation between PMQR and β-lactam resistance genes in the environment is still weak, that the correlations between antimicrobial resistance genes could be weakened by sufficient wastewater treatment, and that the prevalence of PMQR has been implicated in environmental, pathogenic, predatory, anaerobic, and more importantly, human symbiotic bacteria. This work provides a comprehensive analysis of PMQR genes in aquatic environments in Jinan, China, and provides information with which combat with the antimicrobial resistance problem may be fought. PMID:28094345

  13. The drinking water treatment process as a potential source of affecting the bacterial antibiotic resistance.

    Science.gov (United States)

    Bai, Xiaohui; Ma, Xiaolin; Xu, Fengming; Li, Jing; Zhang, Hang; Xiao, Xiang

    2015-11-15

    Two waterworks, with source water derived from the Huangpu or Yangtze River in Shanghai, were investigated, and the effluents were plate-screened for antibiotic-resistant bacteria (ARB) using five antibiotics: ampicillin (AMP), kanamycin (KAN), rifampicin (RFP), chloramphenicol (CM) and streptomycin (STR). The influence of water treatment procedures on the bacterial antibiotic resistance rate and the changes that bacteria underwent when exposed to the five antibiotics at concentration levels ranging from 1 to 100 μg/mL were studied. Multi-drug resistance was also analyzed using drug sensitivity tests. The results indicated that bacteria derived from water treatment plant effluent that used the Huangpu River rather than the Yangtze River as source water exhibited higher antibiotic resistance rates against AMP, STR, RFP and CM but lower antibiotic resistance rates against KAN. When the antibiotic concentration levels ranged from 1 to 10 μg/mL, the antibiotic resistance rates of the bacteria in the water increased as water treatment progressed. Biological activated carbon (BAC) filtration played a key role in increasing the antibiotic resistance rate of bacteria. Chloramine disinfection can enhance antibiotic resistance. Among the isolated ARB, 75% were resistant to multiple antibiotics. Ozone oxidation, BAC filtration and chloramine disinfection can greatly affect the relative abundance of bacteria in the community.

  14. Comparative Resistance of Bacterial Foodborne Pathogens to Non-thermal Technologies for Food Preservation.

    Science.gov (United States)

    Cebrián, Guillermo; Mañas, Pilar; Condón, Santiago

    2016-01-01

    In this paper the resistance of bacterial foodborne pathogens to manosonication (MS), pulsed electric fields (PEFs), high hydrostatic pressure (HHP), and UV-light (UV) is reviewed and compared. The influence of different factors on the resistance of bacterial foodborne pathogens to these technologies is also compared and discussed. Only results obtained under harmonized experimental conditions have been considered. This has allowed us to establish meaningful comparisons and draw significant conclusions. Among the six microorganisms here considered, Staphyloccocus aureus is the most resistant foodborne pathogen to MS and HHP and Listeria monocytogenes to UV. The target microorganism of PEF would change depending on the treatment medium pH. Thus, L. monocytogenes is the most PEF resistant microorganism at neutral pH but Gram-negatives (Escherichia coli, Salmonella spp., Cronobacter sakazakii, Campylobacter jejuni) would display a similar or even higher resistance at acidic pH. It should be noted that, in acidic products, the baroresistance of some E. coli strains would be comparable to that of S. aureus. The factors affecting the resistance of bacterial foodborne pathogens, as well as the magnitude of the effect, varied depending on the technology considered. Inter- and intra-specific differences in microbial resistance to PEF and HHP are much greater than to MS and UV. Similarly, both the pH and aw of the treatment medium highly condition microbial resistance to PEF and HHP but no to MS or UV. Growth phase also drastically affected bacterial HHP resistance. Regarding UV, the optical properties of the medium are, by far, the most influential factor affecting its lethal efficacy. Finally, increasing treatment temperature leads to a significant increase in lethality of the four technologies, what opens the possibility of the development of combined processes including heat. The appearance of sublethally damaged cells following PEF and HHP treatments could also be

  15. COMPARATIVE RESISTANCE OF BACTERIAL FOODBORNE PATHOGENS TO NON-THERMAL TECHNOLOGIES FOR FOOD PRESERVATION

    Directory of Open Access Journals (Sweden)

    Guillermo eCebrián

    2016-05-01

    Full Text Available In this paper the resistance of bacterial foodborne pathogens to manosonication (MS, pulsed electric fields (PEF, high hydrostatic pressure (HHP and UV-light (UV is reviewed and compared. The influence of different factors on the resistance of bacterial foodborne pathogens to these technologies is also compared and discussed. Only results obtained under harmonized experimental conditions have been considered. This has allowed us to establish meaningful comparisons and draw significant conclusions. Among the six microorganisms here considered, Staphyloccocus aureus is the most resistant foodborne pathogen to MS and HHP and Listeria monocytogenes to UV. The target microorganism of PEF would change depending on the treatment medium pH. Thus, L. monocytogenes is the most PEF resistant microorganism at neutral pH but Gram-negatives (Escherichia coli, Salmonella spp., Cronobacter sakazakii, Campylobacter jejuni would display a similar or even higher resistance at acidic pH. It should be noted that, in acidic products, the baroresistance of some E. coli strains would be comparable to that of S. aureus. The factors affecting the resistance of bacterial foodborne pathogens, as well as the magnitude of the effect, varied depending on the technology considered. Inter- and intra-specific differences in microbial resistance to PEF and HHP are much greater than to MS and UV. Similarly, both the pH and aw of the treatment medium highly condition microbial resistance to PEF and HHP but no to MS or UV. Growth phase also drastically affected bacterial HHP resistance. Regarding UV, the optical properties of the medium are, by far, the most influential factor affecting its lethal efficacy. Finally, increasing treatment temperature leads to a significant increase in lethality of the four technologies, what opens the possibility of the development of combined processes including heat. The appearance of sublethally damaged cells following PEF and HHP treatments could

  16. Evaluation of radiation resistance of the bacterial contaminants from femoral heads processed for allogeneic transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rita [Radiation Dosimetry and Processing Group, Defence Laboratory, Jodhpur 342011 (India)], E-mail: singhritadr@yahoo.com; Singh, Durgeshwer [Radiation Dosimetry and Processing Group, Defence Laboratory, Jodhpur 342011 (India)

    2009-09-15

    Femoral heads excised during surgery were obtained from patients who had a fractured neck of the femur and were processed as bone allograft. The bacterial contaminants were isolated from femoral heads at different stages of processing and identified based on morphological characteristics and biochemical tests. Bacterial contaminants on bone were mainly Gram-positive bacilli and cocci (58.3%). Twenty-four isolates from bone samples were screened for resistance to radiation. The D{sub 10} values for Gram-negative bacteria isolated from femoral heads ranged from 0.17 to 0.65 kGy. Higher D{sub 10} values 0.56-1.04 kGy were observed for Gram-positive bacterial isolates.

  17. Antimicrobial activity of human β-defensins against lactic acid bacteria.

    Science.gov (United States)

    Wang, Xiao-Fang; Tian, Fei; Cao, Rui-Ming; Li, Jing; Wu, Sheng-Mei; Guo, Xiao-Kui; Chen, Tong-Xin

    2015-01-01

    In this study, we evaluated the antimicrobial activity of human β-defensin-1 (hBD-1), human β-defensin-2 (hBD-2) and human β-defensin-3 (hBD-3) against three internationally common probiotic strains of lactic acid bacterium. Our results indicated that hBD-1, hBD-2 and hBD-3 at the range of 0.08-10 μg/mL do not have obvious antimicrobial activity against these strains. Viability of Bifidobacterium longum JDM301 (B. longum JDM301), Bifidobacterium lactis HN019 (B. lactis HN019) and Lactobacillus rhamnosus GG (LGG) were still very high even at concentration of 10 μg hBD/mL. Then, we explored the mechanism of resistance by using carbonyl cyanide 3-chlorophenylhydrazone (CCCP) to inhibit efflux pumps. In the presence of CCCP, hBD-1, hBD-2 and hBD-3 exhibited enhanced antibacterial effect against B. longum JDM301 and B. lactis HN019, but not against LGG. Efflux pumps in B. longum JDM301 and B. lactis HN019 may partly contribute to their resistance to hBD-1, hBD-2, and hBD-3.

  18. Improvement of Resistance to Bacterial Blight by Marker-Assisted Selection in a Wide Compatibility Restorer Line of Hybrid Rice

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiu-hua; LUO Yan-chang; LIU Qiao-quan; WANG Shou-hai; WU Hsin-kan; LI Cheng-quan; WANG Zong-yang; WU Shuang; GU Ming-hong; WANG De-zheng; DU Shi-yun

    2004-01-01

    4183 is a promising wide compatibility restorer line with good grain quality. Its hybrid rice Shuangyou 4183 (Shuangjiu A/4183) was registered in Anhui Province in 2003. However, the line and its hybrid rice are susceptible to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). R4183 carrying Xa21 was developed to improve bacterial blight resistance of 4183 through introducing the broad-spectrum resistance gene Xa21 by marker-aided selection. R4183 had similar level of bacterial blight resistance to IRBB21, the resistant donor, while maintained the wide compatibility, restoring ability and other good economic traits of the recurrent parent 4183. Critical issues on improvement of bacterial blight resistance of hybrid rice and breeding strategies were also discussed.

  19. A dual mechanism involved in membrane and nucleic acid disruption of AvBD103b, a new avian defensin from the king penguin, against Salmonella enteritidis CVCC3377.

    Science.gov (United States)

    Teng, Da; Wang, Xiumin; Xi, Di; Mao, Ruoyu; Zhang, Yong; Guan, Qingfeng; Zhang, Jun; Wang, Jianhua

    2014-10-01

    The food-borne bacterial gastrointestinal infection is a serious public health threat. Defensins are evolutionarily conserved innate immune components with broad-spectrum antibacterial activity that do not easily induce resistance. AvBD103b, an avian defensin with potent activity against Salmonella enteritidis, was isolated from the stomach contents of the king penguin (Aptenodytes patagonicus). To elucidate further the antibacterial mechanism of AvBD103b, its effect on the S. enteritidis CVCC3377 cell membrane and intracellular DNA was researched. The cell surface hydrophobicity and a N-phenyl-1-naphthylamine uptake assay demonstrated that AvBD103b treatment increased the cell surface hydrophobicity and outer membrane permeability. Atomic absorption spectrometry, ultraviolet spectrophotometry, flow cytometry, and transmission electron microscopy (TEM) indicated that AvBD103b treatment can lead to the release of the cellular contents and cell death through damage of the membrane. DNA gel retardation and circular dichroism analysis demonstrated that AvBD103b interacted with DNA and intercalated into the DNA base pairs. A cell cycle assay demonstrated that AvBD103b affected cellular functions, such as DNA synthesis. Our results confirmed that AvBD103b exerts its antibacterial activity by damaging the cell membrane and interfering with intracellular DNA, ultimately causing cell death, and suggested that AvBD103b may be a promising candidate as an alternative to antibiotics against S. enteritidis.

  20. Bottlenecks in the transmission of antibiotic resistance from natural ecosystems to human bacterial pathogens

    Directory of Open Access Journals (Sweden)

    Jose L Martinez

    2012-01-01

    Full Text Available It is generally accepted that resistance genes acquired by human pathogens trough horizontal gene transfer have been originated in environmental, non pathogenic bacteria. As the consequence, there exists an increasing concern on the role that natural, non-clinical ecosystems, may play on the evolution of resistance. Recent studies have shown that the variability of determinants that can provide antibiotic resistance upon their expression in a heterologous host is much larger than what is actually found in human pathogens. Along the review, the role that different processes as founder effect, ecological connectivity, fitness costs or second-order selection may have on the establishment of a specific resistance determinant in the population of bacterial pathogens is analysed.

  1. Benchmarking of methods for identification of antimicrobial resistance genes in bacterial whole genome data

    DEFF Research Database (Denmark)

    Clausen, Philip T. L. C.; Zankari, Ea; Aarestrup, Frank Møller;

    2016-01-01

    Next generation sequencing (NGS) may be an alternative to phenotypic susceptibility testing for surveillance and clinical diagnosis. However, current bioinformatics methods may be associated with false positives and negatives. In this study, a novel mapping method was developed and benchmarked...... to two different methods in current use for identification of antibiotic resistance genes in bacterial WGS data. A novel method, KmerResistance, which examines the co-occurrence of k-mers between the WGS data and a database of resistance genes, was developed. The performance of this method was compared...... with two previously described methods; ResFinder and SRST2, which use an assembly/BLAST method and BWA, respectively, using two datasets with a total of 339 isolates, covering five species, originating from the Oxford University Hospitals NHS Trust and Danish pig farms. The predicted resistance...

  2. Hybrid Rice Resistant to Bacterial Leaf Blight Developed By Marker Assisted Selection

    Institute of Scientific and Technical Information of China (English)

    CAO; Li-yong; ZHUANG; Jie-yun; YUAN; Shou-jiang; ZHAN; Xiao-deng; ZHENG; Kang-le; CHENG; Shi-hua

    2003-01-01

    Through recurrént backcrossing in combination with molecular marker-assisted selection (MAS), restorer lines R8006 and R1176 carrying Xa-21 , a gene having broad-spectrum resistance to rice bacterial leaf blight, were selected. By crossing the two lines to CMS line Zhong 9A, two new hybrid rice combinations, Zhongyou 6 and Zhongyou 1176 were developed. The hybrids showed high resistance to diseases, good grain quality and high yielding potential in national and provincial adaptability and yield trials.

  3. Insights in Nanoparticle-Bacterium Interactions: New Frontiers to Bypass Bacterial Resistance to Antibiotics.

    Science.gov (United States)

    Diab, Roudayna; Khameneh, Bahman; Joubert, Olivier; Duval, Raphael

    2015-01-01

    Nanotechnology has been revealed as a fundamental approach for antibiotics delivery. In this paper, recent findings demonstrating the superiority of nanocarried-antibiotics over "naked" ones and the ways by which nanoparticles can help to overwhelm bacterial drug resistance are reviewed. The second part of this paper sheds light on nanoparticle-bacterium interaction patterns. Finally, key factors affecting the effectiveness of nanoparticles interactions with bacteria are discussed.

  4. An efficient system for intracellular delivery of beta-lactam antibiotics to overcome bacterial resistance

    OpenAIRE

    Nadia Abed; Fatouma Saïd-Hassane; Fatima Zouhiri; Julie Mougin; Valérie Nicolas; Didier Desmaële; Ruxandra Gref; Patrick Couvreur

    2015-01-01

    The “Golden era” of antibiotics is definitely an old story and this is especially true for intracellular bacterial infections. The poor intracellular bioavailability of antibiotics reduces the efficency of many treatments and thereby promotes resistances. Therefore, the development of nanodevices coupled with antibiotics that are capable of targeting and releasing the drug into the infected-cells appears to be a promising solution to circumvent these complications. Here, we took advantage of ...

  5. Antibiotic discovery: combatting bacterial resistance in cells and in biofilm communities.

    Science.gov (United States)

    Penesyan, Anahit; Gillings, Michael; Paulsen, Ian T

    2015-03-24

    Bacterial resistance is a rapidly escalating threat to public health as our arsenal of effective antibiotics dwindles. Therefore, there is an urgent need for new antibiotics. Drug discovery has historically focused on bacteria growing in planktonic cultures. Many antibiotics were originally developed to target individual bacterial cells, being assessed in vitro against microorganisms in a planktonic mode of life. However, towards the end of the 20th century it became clear that many bacteria live as complex communities called biofilms in their natural habitat, and this includes habitats within a human host. The biofilm mode of life provides advantages to microorganisms, such as enhanced resistance towards environmental stresses, including antibiotic challenge. The community level resistance provided by biofilms is distinct from resistance mechanisms that operate at a cellular level, and cannot be overlooked in the development of novel strategies to combat infectious diseases. The review compares mechanisms of antibiotic resistance at cellular and community levels in the light of past and present antibiotic discovery efforts. Future perspectives on novel strategies for treatment of biofilm-related infectious diseases are explored.

  6. Antibiotic Discovery: Combatting Bacterial Resistance in Cells and in Biofilm Communities

    Directory of Open Access Journals (Sweden)

    Anahit Penesyan

    2015-03-01

    Full Text Available Bacterial resistance is a rapidly escalating threat to public health as our arsenal of effective antibiotics dwindles. Therefore, there is an urgent need for new antibiotics. Drug discovery has historically focused on bacteria growing in planktonic cultures. Many antibiotics were originally developed to target individual bacterial cells, being assessed in vitro against microorganisms in a planktonic mode of life. However, towards the end of the 20th century it became clear that many bacteria live as complex communities called biofilms in their natural habitat, and this includes habitats within a human host. The biofilm mode of life provides advantages to microorganisms, such as enhanced resistance towards environmental stresses, including antibiotic challenge. The community level resistance provided by biofilms is distinct from resistance mechanisms that operate at a cellular level, and cannot be overlooked in the development of novel strategies to combat infectious diseases. The review compares mechanisms of antibiotic resistance at cellular and community levels in the light of past and present antibiotic discovery efforts. Future perspectives on novel strategies for treatment of biofilm-related infectious diseases are explored.

  7. Transgenic Rice Plants Harboring Genomic DNA from Zizania latifolia Confer Bacterial Blight Resistance

    Institute of Scientific and Technical Information of China (English)

    SHEN Wei-wei; SONG Cheng-li; CHEN Jie; Fu Ya-ping; Wu Jian-li; JIANG Shao-mei

    2011-01-01

    Based on the sequence of a resistance gene analog FZ14 derived from Zizania latifolia (Griseb.),a pair of specific PCR primers FZ14P1/FZ14P2 was designed to isolate candidate disease resistance gene.The pooled-PCR approach was adopted using the primer pair to screen a genomic transformation-competent artificial chromosome (TAC) library derived from Z.latifolia.A positive TAC clone (ZR1) was obtained and confirmed by sequence analysis.The results indicated that ZR1 consisted of conserved motifs similar to P-loop (kinase 1a),kinase 2,kinase 3a and GLPL (Gly-Leu-Pro-Leu),suggesting that it could be a portion of NBS-LRR type of resistance gene.Using Agrobacterium-mediated transformation of Nipponbare mature embryo,a total of 48 independent transgenic T0 plants were obtained.Among them,36 plants were highly resistant to the virulent bacterial blight strain P×O71.The results indicate that ZR1 contains at least one functional bacterial blight resistance gene.

  8. Therapeutic potential of antifungal plant and insect defensins

    NARCIS (Netherlands)

    Thevissen, K.; Kristensen, H.H.; Thomma, B.P.H.J.; Cammue, B.P.A.; François, I.E.J.A.

    2007-01-01

    To defend themselves against invading fungal pathogens, plants and insects largely depend on the production of a wide array of antifungal molecules, including antimicrobial peptides such as defensins. Interestingly, plant and insect defensins display antimicrobial activity not only against plant and

  9. Enteric defensins are essential regulators of intestinal microbial ecology

    NARCIS (Netherlands)

    Salzman, Nita H.; Hung, Kuiechun; Haribhai, Dipica; Chu, Hiutung; Karlsson-Sjoeberg, Jenny; Amir, Elad; Teggatz, Paul; Barman, Melissa; Hayward, Michael; Eastwood, Daniel; Stoel, Maaike; Zhou, Yanjiao; Sodergren, Erica; Weinstock, George M.; Bevins, Charles L.; Williams, Calvin B.; Bos, Nicolaas A.

    2010-01-01

    Antimicrobial peptides are important effectors of innate immunity throughout the plant and animal kingdoms. In the mammalian small intestine, Paneth cell alpha-defensins are antimicrobial peptides that contribute to host defense against enteric pathogens. To determine if alpha-defensins also govern

  10. Localization of b-defensin genes in non human primates

    Directory of Open Access Journals (Sweden)

    M Ventura

    2009-06-01

    Full Text Available Defensins are a family of host defence peptides that play an important role in the innate immunity of mammalian and avian species. In humans, four b-defensins have been isolated so far, corresponding to the products of the genes DEFB1 (h-BD1, GenBank accession number NM_005218; DEFB4 (h-Bd2, NM_004942.2, DEFB103 (h-BD3, NM_018661; and DEFB104 (hBD4, NM_080389 mapping on chromosome 8p23.22. We have localized b- defensin genes on metaphasic chromosomes of great apes and several non-human primate species to determine their physical mapping. Using fluorescent in situ hybridization and BAC probes containing the four b-defensin genes, we have mapped the homologous regions to the b-defensin genes on chromosome 8p23-p.22 in non-human primates, while no signals were detected on prosimians chromosomes.

  11. Antibiotics pollution in Jiulong River estuary: source, distribution and bacterial resistance.

    Science.gov (United States)

    Zheng, Senlin; Qiu, Xiaoyan; Chen, Bin; Yu, Xingguang; Liu, Zhenghua; Zhong, Guopei; Li, Hengyang; Chen, Meng; Sun, Guangda; Huang, Hao; Yu, Weiwei; Freestone, David

    2011-09-01

    To gain insight into the antibiotic pollution in the Jiulong River estuary and the pollutant sources, we analyzed the concentration of 22 widely-used antibiotics in water samples collected from the river and estuary, 17 and 18 sampling sites, respectively. Contamination with sulfonamides, quinolones and chloramphenicols was frequently detected and the distribution pattern of antibiotics suggested that most of the pollutants are from the Jiulong River, especially from the downstream watersheds. To reveal the ecological effects, we isolated 35 bacterial strains from the estuary and analyzed their antibiotic resistance to the eight most frequently detected antibiotics. The bacteria were subsequently classified into seven different genera by 16SrDNA sequencing. Up to 97.1% of the bacteria showed resistance and 70.6% of strains showed multi-resistance to these antibiotics, especially to sulfonamides. This study demonstrated a pattern of antibiotic contamination in the Jiulong River and its estuary and illustrated high bacterial antibiotic resistance which was significantly correlated with the average antibiotics concentrations and detected frequencies in the estuary.

  12. Exposure of juvenile Leghorn chickens to lead acetate enhances antibiotic resistance in enteric bacterial flora.

    Science.gov (United States)

    Nisanian, M; Holladay, S D; Karpuzoglu, E; Kerr, R P; Williams, S M; Stabler, L; McArthur, J Vaun; Tuckfield, R Cary; Gogal, R M

    2014-04-01

    Heavy metals have been implicated for their ability to increase antibiotic resistance in bacteria collected from polluted waters, independent of antibiotic exposure. Specific-pathogen-free Leghorn chickens were therefore given Pb acetate in the drinking water to expose the enteric bacteria to Pb and to determine if antibiotic resistance changed in these bacteria. Concentrations of Pb used were 0.0, 0.01, 0.1, 1.0, or 10.0 mM; birds given the highest 2 concentrations showed signs of moribundity and dehydration and were removed from the study. Vent culture samples were collected for bacterial cultures on d 0 before Pb exposure, d 7 and 14, and then birds were euthanized by CO2 gas for necropsy on d 14, at which time intestinal contents were also collected for bacterial cultures. Fecal swabs but not intestinal samples from Pb-exposed birds contained isolates that had significantly elevated antibiotic resistance. Some of the isolates contained bacteria that were resistant to up to 20 antibiotics. These results suggest the need for repeated studies in chickens infected with zoonotic pathogens.

  13. A retrospective analysis of skin bacterial colonisation, susceptibility and resistance in atopic dermatitis and impetigo patients.

    Science.gov (United States)

    Salah, Louai A; Faergemann, Jan

    2015-05-01

    Atopic dermatitis (AD) and impetigo are skin conditions where bacterial colonisation and infection, especially with Staphylococcus aureus play an important role. We compared skin bacterial population, resistance patterns and choice of antimicrobial agents in patients diagnosed with AD and impetigo during 2005 and 2011 in our department. Number of positive cultures in the AD group were 40 and 53 in 2005 and 2011, with S. aureus found in 97.5% and 100%, respectively. Differences in resistance were marginal. In impetigo, S. aureus was found in all 70 patients in 2005 and all 40 patients in 2011. Antibiotic resistance to specifically fusidic acid was more common in 2005 impetigo patients (22.8%) versus 2011 (5%) (p = 0.078). The most commonly used oral antimicrobial was cefadroxil (in 57.5% and 52.8% of AD and 58.6% and 35% of impetigo patients in 2005 and 2011, respectively). Our observations confirm the high prevalence of S. aureus in both diseases and, interestingly, show a declining resistance trend in impetigo.

  14. Structural Studies of Bacterial Enzymes and their Relation to Antibiotic Resistance Mechanisms - Final Paper

    Energy Technology Data Exchange (ETDEWEB)

    Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-27

    By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β- lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes

  15. Quantitative analysis of resistance in cotton to three new isolates of the bacterial blight pathogen.

    Science.gov (United States)

    Wallace, T P; El-Zik, K M

    1990-04-01

    Genetic variability for virulence of the bacterial blight pathogen [Xanthomonas campestris pv malvacearum (Smith) Dye] on cotton (Gossypium hirsutum L.) has been shown by the identification of 19 races of the pathogen based on disease reactions of a set of ten host differentials. This study was conducted to determine the inheritance of host resistance to three recently identified isolates of X. campestris pv malvacearum, which are virulent on the entire set of differentials. True leaves of Tamcot CAMD-E, LEBOCAS-3-80, Stoneville 825, and their f1, F2, and backcross progenies were wound-inoculated in the field with separate bacterial suspensions of the virulent HV3, HV7, and Sudan isolates of the pathogen. LEBOCAS-3-80 was replaced with S295, a new immune cultivar, for a greenhouse study in which both cotyledons and true leaves were inoculated. Disease reactions were rated on a scale of 1-10, and genetic models were proposed utilizing generation means analysis. Dominance, when significant, was in the direction of resistance in all but one cross-isolate combination. Digenic interaction components indicated a duplicate type. Narrow-sense heritability for resistance ranged from 0.59 to 0.68; therefore, primarily additive-genetic variability among the selected cutlivars was detected, indicating that breeding for improved resistance to these isolates is a practical goal.

  16. A conservative region of the mercuric reductase gene (mera) as a molecular marker of bacterial mercury resistance

    Science.gov (United States)

    Sotero-Martins, Adriana; de Jesus, Michele Silva; Lacerda, Michele; Moreira, Josino Costa; Filgueiras, Ana Luzia Lauria; Barrocas, Paulo Rubens Guimarães

    2008-01-01

    The most common bacterial mercury resistance mechanism is based on the reduction of Hg(II) to Hg0, which is dependent of the mercuric reductase enzyme (MerA) activity. The use of a 431 bp fragment of a conservative region of the mercuric reductase (merA) gene was applied as a molecular marker of this mechanism, allowing the identification of mercury resistant bacterial strains. PMID:24031221

  17. High prevalence of multidrug resistance in bacterial uropathogens from Kathmandu, Nepal

    Directory of Open Access Journals (Sweden)

    Baral Pankaj

    2012-01-01

    Full Text Available Abstract Background Urinary Tract Infection (UTI is one of the most common infectious diseases and people of all age-groups and geographical locations are affected. The impact of disease is even worst in low-resource developing countries due to unaware of the UTIs caused by multidrug-resistant (MDR pathogens and the possibility of transfer of MDR traits between them. The present study aimed to determine the prevalence of MDR bacterial isolates from UTI patients, the antibiotic resistance pattern and the conjugational transfer of multidrug resistance phenotypes in Escherichia coli (E. coli. Results Two hundred and nineteen bacterial isolates were recovered from 710 urine samples at Kathmandu Model hospital during the study period. All samples and isolates were investigated by standard laboratory procedures. Among the significant bacterial growth (30.8%, 219 isolates, 41.1% isolates were MDR. The most prevailing organism, E. coli (81.3%, 178 isolates was 38.2% MDR, whereas second most common organism, Citrobacter spp. (5%, 11 isolates was found 72.7% MDR. Extended-spectrum β-lactamase (ESBL production was detected in 55.2% of a subset of MDR E. coli isolates. Among the 29 MDR E. coli isolates, plasmids of size ranging 2-51 kb were obtained with different 15 profiles. The most common plasmid of size 32 kb was detected in all of the plasmid-harbored E. coli strains. The majority of E. coli isolates investigated for the multidrug resistance transfer were able to transfer plasmid-mediated MDR phenotypes along with ESBL pattern with a frequency ranging from 0.3 × 10-7 to 1.5 × 10-7 to an E. coli HB101 recipient strain by conjugation. Most of the donor and recipient strain showed high levels of minimum inhibitory concentration (MIC values for commonly-used antibiotics. Conclusions The high prevalence of multidrug resistance in bacterial uropathogens was observed. Particularly, resistance patterns were alarmingly higher for amoxycillin, co

  18. Exposure to phages has little impact on the evolution of bacterial antibiotic resistance on drug concentration gradients

    OpenAIRE

    Zhang, Quan-Guo

    2014-01-01

    The use of phages for treating bacterial pathogens has recently been advocated as an alternative to antibiotic therapy. Here, we test a hypothesis that bacteria treated with phages may show more limited evolution of antibiotic resistance as the fitness costs of resistance to phages may add to those of antibiotic resistance, further reducing the growth performance of antibiotic-resistant bacteria. We did this by studying the evolution of phage-exposed and phage-free Pseudomonas fluorescens cul...

  19. Ceragenins – a new weapon to fight multidrug resistant bacterial infections

    Directory of Open Access Journals (Sweden)

    Urszula Surel

    2014-09-01

    Full Text Available Growing antibiotic resistance among pathogenic microorganisms is one of the most challenging problems. Often, a single mutation in a bacterial cell leads to the formation of a new drug resistance mechanism. The ceragenins are a novel class of antibiotic, offering great promise in future treatment of infections. These cationic antimicrobial lipids are net positively charged cholic acid derivates that are electrostatically attracted to the negatively charged membranes of bacteria, certain viruses, fungi, and protozoa. After membrane insertion, they interfere with membrane organisation, resulting in membrane dysfunction and cell death. This review focuses on the broad spectrum of antibacterial activity of ceragenins, and their potential to become a new group of antibiotics for prevention and treatment of infections, especially those caused by multidrug-resistant bacteria.

  20. Survival and evolution of a large multidrug resistance plasmid in new clinical bacterial hosts

    DEFF Research Database (Denmark)

    Porse, Andreas; Schønning, Kristian; Munck, Christian;

    2016-01-01

    Large conjugative plasmids are important drivers of bacterial evolution and contribute significantly to the dissemination of antibiotic resistance. Although plasmid borne multidrug resistance is recognized as one of the main challenges in modern medicine, the adaptive forces shaping the evolution...... sequencing to show that the long-term persistence and molecular integrity of the plasmid is highly influenced by multiple factors within a 25 kb plasmid region constituting a host-dependent burden. In the E. coli hosts investigated here, improved plasmid stability readily evolves via IS26 mediated deletions...... consistently followed by all evolved E. coli lineages exposes a trade-off between horizontal and vertical transmission that may ultimately limit the dissemination potential of clinical multidrug resistance plasmids in these hosts....

  1. Resistance to Bacterial Leaf Blight in a Somaclonal Rice Mutant HX-3 at Cellular Level

    Institute of Scientific and Technical Information of China (English)

    GAO Dong-ying; ZHOU Yi-hong; HUANG Xue-qing; SUN Li-hua; LIU Ai-min

    2004-01-01

    The interaction between rice host and its pathogen Xanthomonas oryzae pv. oryzae (Xoo) at cellular level was studied by using a resistant somaclonal mutant HX-3 and its susceptable donor Minghui 63. After inoculation with Xoo strain Zhe 173 (Chinese pathotype Ⅳ), the activity of superoxide dismutase (SOD) and peroxidase (POD) in the callus of Minghui 63 was increased dramatically, and the active oxygen(O2 - .) was produced at a higher rate; Meanwhile, the callus grew slowly with the reduction of protein content. Compared to the activity of SOD and POD, the production rate of O2-. and the fresh weight in HX-3 callus varied little after the inoculation. It could be proposed that there were great differences between the resistance of HX-3 and Mighui 63 at cellular level. There was no difference detected concerning resistance to bacterial leaf blight in HX-3 between the plant and the callus.

  2. Evolving trends in Streptococcus pneumoniae resistance: implications for therapy of community-acquired bacterial pneumonia.

    Science.gov (United States)

    Jones, Ronald N; Jacobs, Michael R; Sader, Helio S

    2010-09-01

    Pneumonia is a major infectious disease associated with significant morbidity, mortality and utilisation of healthcare resources. Streptococcus pneumoniae is the predominant pathogen in community-acquired pneumonia (CAP), accounting for 20-60% of bacterial cases. Emergence of multidrug-resistant S. pneumoniae has become a significant problem in the management of CAP. Although pneumococcal conjugate vaccine usage in children has led to significant decreases in morbidity and mortality due to S. pneumoniae in all age groups, disease management has been further complicated by the unexpected increase in resistant serotypes, such as 19A, in some regions. Until rapid and accurate diagnostic tests become available, initial treatment of CAP will remain empirical. Thus, selection of appropriate antimicrobial therapy for CAP must be based on prediction of the most likely pathogens and their local antimicrobial susceptibility patterns. This article reviews information on antimicrobial resistance patterns amongst S. pneumoniae and implications for managing CAP.

  3. Induction of bacterial antibiotic resistance by mutagenic halogenated nitrogenous disinfection byproducts.

    Science.gov (United States)

    Lv, Lu; Yu, Xin; Xu, Qian; Ye, Chengsong

    2015-10-01

    Halogenated nitrogenous disinfection byproducts (N-DBPs) raise concerns regarding their mutagenicity and carcinogenicity threatening public health. However, environmental consequence of their mutagenicity has received less attention. In this study, the effect of halogenated N-DBPs on bacterial antibiotic resistance (BAR) was investigated. After exposure to bromoacetamide (BAcAm), trichloroacetonitrile (TCAN) or tribromonitromethane (TBNM), the resistance of Pseudomonas aeruginosa PAO1 to both individual and multiple antibiotics (ciprofloxacin, gentamicin, polymyxin B, rifampin, tetracycline, ciprofloxacin + gentamicin and ciprofloxacin + tetracycline) was increased, which was predominantly ascribed to the overexpression of efflux pumps. The mechanism of this effect was demonstrated to be mutagenesis through sequencing and analyzing antibiotic resistance genes. The same induction phenomena also appeared in Escherichia coli, suggesting this effect may be universal to waterborne pathogens. Therefore, more attention should be given to halogenated N-DBPs, as they could increase not only genotoxicological risks but also epidemiological risks of drinking water.

  4. Design and activity of a cyclic mini-β-defensin analog: a novel antimicrobial tool.

    Science.gov (United States)

    Scudiero, Olga; Nigro, Ersilia; Cantisani, Marco; Colavita, Irene; Leone, Marilisa; Mercurio, Flavia Anna; Galdiero, Massimiliano; Pessi, Antonello; Daniele, Aurora; Salvatore, Francesco; Galdiero, Stefania

    2015-01-01

    We have designed a cyclic 17-amino acid β-defensin analog featuring a single disulfide bond. This analog, designated "AMC" (ie, antimicrobial cyclic peptide), combines the internal hydrophobic domain of hBD1 and the C-terminal charged region of hBD3. The novel peptide was synthesized and characterized by nuclear magnetic resonance spectroscopy. The antimicrobial activities against gram-positive and gram-negative bacteria as well as against herpes simplex virus type 1 were analyzed. The cytotoxicity and serum stability were assessed. Nuclear magnetic resonance of AMC in aqueous solution suggests that the structure of the hBD1 region, although not identical, is preserved. Like the parent defensins, AMC is not cytotoxic for CaCo-2 cells. Interestingly, AMC retains the antibacterial activity of the parent hBD1 and hBD3 against Pseudomonas aeruginosa, Enterococcus faecalis, and Escherichia coli, and exerts dose-dependent activity against herpes simplex virus type 1. Moreover, while the antibacterial and antiviral activities of the oxidized and reduced forms of the parent defensins are similar, those of AMC are significantly different, and oxidized AMC is also considerably more stable in human serum. Taken together, our data also suggest that this novel peptide may be added to the arsenal of tools available to combat antibiotic-resistant infectious diseases, particularly because of its potential for encapsulation in a nanomedicine vector.

  5. The repertoire of equine intestinal α-defensins

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    Tetens Jens

    2009-12-01

    Full Text Available Abstract Background Defensins represent an important class of antimicrobial peptides. These effector molecules of the innate immune system act as endogenous antibiotics to protect the organism against infections with pathogenic microorganisms. Mammalian defensins are classified into three distinct sub-families (α-, β- and θ-defensins according to their specific intramolecular disulfide-bond pattern. The peptides exhibit an antimicrobial activity against a broad spectrum of microorganisms including bacteria and fungi. Alpha-Defensins are primarily synthesised in neutrophils and intestinal Paneth cells. They play a role in the pathogenesis of intestinal diseases and may regulate the flora of the intestinal tract. An equine intestinal α-defensin (DEFA1, the first characterised in the Laurasiatheria, shows a broad antimicrobial spectrum against human and equine pathogens. Here we report a first investigation of the repertoire of equine intestinal α-defensins. The equine genome was screened for putative α-defensin genes by using known α-defensin sequences as matrices. Based on the obtained sequence information, a set of oligonucleotides specific to the α-defensin gene-family was designed. The products generated by reverse-transcriptase PCR with cDNA from the small intestine as template were sub-cloned and numerous clones were sequenced. Results Thirty-eight equine intestinal α-defensin transcripts were determined. After translation it became evident that at least 20 of them may code for functional peptides. Ten transcripts lacked matching genomic sequences and for 14 α-defensin genes apparently present in the genome no appropriate transcript could be verified. In other cases the same genomic exons were found in different transcripts. Conclusions The large repertoire of equine α-defensins found in this study points to a particular importance of these peptides regarding animal health and protection from infectious diseases. Moreover, these

  6. Increased expression and levels of human β defensins (hBD2 and hBD4 in adults with dental caries

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    Girolamo Jose Barrera

    2013-09-01

    Full Text Available Introduction: Defensins are small anti-microbial peptides produced by epithelial cells. These peptides have a broad range of actions against microorganisms, including Gram-positive and Gram-negative bacteria.Human defensins are classifi ed into two subfamilies, the α-, and β- defensins, which differ in their distribution of disulphide bonds between the six conserved cysteine residues. Defensins are found in salivaand others compartments of the body. Human β defensins 2 (hBD2, beta defensins 4 (hBD4 and alpha defensins 4 (hNP4 in saliva may contributes to vulnerability or resistance to caries. This study aimed to determine a possible correlation between caries and levels of defensins measuring the expression in gingival tissue and concentrations in saliva samples.Methods: Oral examinations were performed on 100 adults of both genders (18-30 years old, and unstimulated whole saliva was collected for immunoassays of the three peptides and for the salivary pH, buffercapacity, protein, and peroxidase activity. mRNA levels of defensins in gingival sample were assessed by semi-quantitative RT-PCR technique.Results: The median salivary levels of hBD2 and hBD4 were 1.88 μg/ml and 0.86 μg/ml respectively for the caries-free group (n=44 and 7.26 μ/ml (hBD2 and 4.25 μg/ml (hBD4 for all subjects with evidenceof caries (n=56. There was no difference in the levels of hNP4, salivary pH, and proteins between groups, however the peroxidase activity and buffer capacity (interval 6.0-5.0 were reduced in caries group. Transcriptional levels of hBD2 and hBD4 did correlate with caries experience, the mRNA expression of hBD2 and hBD4 were signifi cantly higher in patients with caries than in patients with no-caries (p Conclusion: We conclude that high salivary levels and expression of beta defensins, low peroxidase activity and buffer capacity may represent a biological response of oral tissue to caries. Our observation couldlead to new ways to prevent caries

  7. Increased expression and levels of human β defensins (hBD2 and hBD4 in adults with dental caries

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    Girolamo Jose Barrera

    2013-09-01

    Full Text Available Introduction: Defensins are small anti-microbial peptides produced by epithelial cells. These peptides have a broad range of actions against microorganisms, including Gram-positive and Gram-negative bacteria.Human defensins are classifi ed into two subfamilies, the α-, and β- defensins, which differ in their distribution of disulphide bonds between the six conserved cysteine residues. Defensins are found in salivaand others compartments of the body. Human β defensins 2 (hBD2, beta defensins 4 (hBD4 and alpha defensins 4 (hNP4 in saliva may contributes to vulnerability or resistance to caries. This study aimed to determine a possible correlation between caries and levels of defensins measuring the expression in gingival tissue and concentrations in saliva samples.Methods: Oral examinations were performed on 100 adults of both genders (18-30 years old, and unstimulated whole saliva was collected for immunoassays of the three peptides and for the salivary pH, buffercapacity, protein, and peroxidase activity. mRNA levels of defensins in gingival sample were assessed by semi-quantitative RT-PCR technique.Results: The median salivary levels of hBD2 and hBD4 were 1.88 μg/ml and 0.86 μg/ml respectively for the caries-free group (n=44 and 7.26 μ/ml (hBD2 and 4.25 μg/ml (hBD4 for all subjects with evidenceof caries (n=56. There was no difference in the levels of hNP4, salivary pH, and proteins between groups, however the peroxidase activity and buffer capacity (interval 6.0-5.0 were reduced in caries group. Transcriptional levels of hBD2 and hBD4 did correlate with caries experience, the mRNA expression of hBD2 and hBD4 were signifi cantly higher in patients with caries than in patients with no-caries (p < 0.01.Conclusion: We conclude that high salivary levels and expression of beta defensins, low peroxidase activity and buffer capacity may represent a biological response of oral tissue to caries. Our observation couldlead to new ways to prevent

  8. A Scorpion Defensin BmKDfsin4 Inhibits Hepatitis B Virus Replication in Vitro

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    Zhengyang Zeng

    2016-04-01

    Full Text Available Hepatitis B virus (HBV infection is a major worldwide health problem which can cause acute and chronic hepatitis and can significantly increase the risk of liver cirrhosis and primary hepatocellular carcinoma (HCC. Nowadays, clinical therapies of HBV infection still mainly rely on nucleotide analogs and interferons, the usage of which is limited by drug-resistant mutation or side effects. Defensins had been reported to effectively inhibit the proliferation of bacteria, fungi, parasites and viruses. Here, we screened the anti-HBV activity of 25 scorpion-derived peptides most recently characterized by our group. Through evaluating anti-HBV activity and cytotoxicity, we found that BmKDfsin4, a scorpion defensin with antibacterial and Kv1.3-blocking activities, has a comparable high inhibitory rate of both HBeAg and HBsAg in HepG2.2.15 culture medium and low cytotoxicity to HepG2.2.15. Then, our experimental results further showed that BmKDfsin4 can dose-dependently decrease the production of HBV DNA and HBV viral proteins in both culture medium and cell lysate. Interestingly, BmKDfsin4 exerted high serum stability. Together, this study indicates that the scorpion defensin BmKDfsin4 also has inhibitory activity against HBV replication along with its antibacterial and potassium ion channel Kv1.3-blocking activities, which shows that BmKDfsin4 is a uniquely multifunctional defensin molecule. Our work also provides a good molecule material which will be used to investigate the link or relationship of its antiviral, antibacterial and ion channel–modulating activities in the future.

  9. A Scorpion Defensin BmKDfsin4 Inhibits Hepatitis B Virus Replication in Vitro

    Science.gov (United States)

    Zeng, Zhengyang; Zhang, Qian; Hong, Wei; Xie, Yingqiu; Liu, Yun; Li, Wenxin; Wu, Yingliang; Cao, Zhijian

    2016-01-01

    Hepatitis B virus (HBV) infection is a major worldwide health problem which can cause acute and chronic hepatitis and can significantly increase the risk of liver cirrhosis and primary hepatocellular carcinoma (HCC). Nowadays, clinical therapies of HBV infection still mainly rely on nucleotide analogs and interferons, the usage of which is limited by drug-resistant mutation or side effects. Defensins had been reported to effectively inhibit the proliferation of bacteria, fungi, parasites and viruses. Here, we screened the anti-HBV activity of 25 scorpion-derived peptides most recently characterized by our group. Through evaluating anti-HBV activity and cytotoxicity, we found that BmKDfsin4, a scorpion defensin with antibacterial and Kv1.3-blocking activities, has a comparable high inhibitory rate of both HBeAg and HBsAg in HepG2.2.15 culture medium and low cytotoxicity to HepG2.2.15. Then, our experimental results further showed that BmKDfsin4 can dose-dependently decrease the production of HBV DNA and HBV viral proteins in both culture medium and cell lysate. Interestingly, BmKDfsin4 exerted high serum stability. Together, this study indicates that the scorpion defensin BmKDfsin4 also has inhibitory activity against HBV replication along with its antibacterial and potassium ion channel Kv1.3-blocking activities, which shows that BmKDfsin4 is a uniquely multifunctional defensin molecule. Our work also provides a good molecule material which will be used to investigate the link or relationship of its antiviral, antibacterial and ion channel–modulating activities in the future. PMID:27128943

  10. Antibiotics, Antibiotic Resistance Genes, and Bacterial Community Composition in Fresh Water Aquaculture Environment in China.

    Science.gov (United States)

    Xiong, Wenguang; Sun, Yongxue; Zhang, Tong; Ding, Xueyao; Li, Yafei; Wang, Mianzhi; Zeng, Zhenling

    2015-08-01

    Environmental antibiotic resistance has drawn increasing attention due to its great threat to human health. In this study, we investigated concentrations of antibiotics (tetracyclines, sulfonamides and (fluoro)quinolones) and abundances of antibiotic resistance genes (ARGs), including tetracycline resistance genes, sulfonamide resistance genes, and plasmid-mediated quinolone resistance genes, and analyzed bacterial community composition in aquaculture environment in Guangdong, China. The concentrations of sulfametoxydiazine, sulfamethazine, sulfamethoxazole, oxytetracycline, chlorotetracycline, doxycycline, ciprofloxacin, norfloxacin, and enrofloxacin were as high as 446 μg kg(-1) and 98.6 ng L(-1) in sediment and water samples, respectively. The relative abundances (ARG copies/16S ribosomal RNA (rRNA) gene copies) of ARGs (sul1, sul2, sul3, tetM, tetO, tetW, tetS, tetQ, tetX, tetB/P, qepA, oqxA, oqxB, aac(6')-Ib, and qnrS) were as high as 2.8 × 10(-2). The dominant phyla were Proteobacteria, Bacteroidetes, and Firmicutes in sediment samples and Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The genera associated with pathogens were also observed, such as Acinetobacter, Arcobacter, and Clostridium. This study comprehensively investigated antibiotics, ARGs, and bacterial community composition in aquaculture environment in China. The results indicated that fish ponds are reservoirs of ARGs and the presence of potential resistant and pathogen-associated taxonomic groups in fish ponds might imply the potential risk to human health.

  11. Aerobic bacterial profile and antibiotic resistance in patients with diabetic foot infections

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    Michele Cezimbra Perim

    2015-10-01

    Full Text Available ABSTRACTINTRODUCTION: This study aimed to determine the frequencies of bacterial isolates cultured from diabetic foot infections and assess their resistance and susceptibility to commonly used antibiotics.METHODS: This prospective study included 41 patients with diabetic foot lesions. Bacteria were isolated from foot lesions, and their antibiotic susceptibility pattern was determined using the Kirby-Bauer disk diffusion method and/or broth method [minimum inhibitory concentration (MIC].RESULTS: The most common location of ulceration was the toe (54%, followed by the plantar surface (27% and dorsal portion (19%. A total of 89 bacterial isolates were obtained from 30 patients. The infections were predominantly due to Gram-positive bacteria and polymicrobial bacteremia. The most commonly isolated Gram-positive bacteria were Staphylococcus aureus, followed by Staphylococcus saprophyticus, Staphylococcus epidermidis, Streptococcus agalactiae, and Streptococcus pneumoniae. The most commonly isolated Gram-negative bacteria were Proteus spp. and Enterobacterspp., followed by Escherichia coli, Pseudomonasspp., and Citrobacterspp. Nine cases of methicillin-resistant Staphylococcus aureus (MRSA had cefoxitin resistance, and among these MRSA isolates, 3 were resistant to vancomycin with the MIC technique. The antibiotic imipenem was the most effective against both Gram-positive and Gram-negative bacteria, and gentamicin was effective against Gram-negative bacteria.CONCLUSIONS: The present study confirmed the high prevalence of multidrug-resistant pathogens in diabetic foot ulcers. It is necessary to evaluate the different microorganisms infecting the wound and to know the antibiotic susceptibility patterns of the isolates from the infected wound. This knowledge is crucial for planning treatment with the appropriate antibiotics, reducing resistance patterns, and minimizing healthcare costs.

  12. Antibiotic resistance genes occurrence and bacterial community composition in the Liuxi River

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    Wenguang eXiong

    2014-12-01

    Full Text Available Antibiotic resistance genes (ARGs in the environment have paid great concern due to their health risk. We investigated antibiotics concentrations (tetracyclines, sulfonamides and fluoroquinolones, ARGs abundances (tetracycline, sulfonamide and plasmid-mediated quinolone resistance (PMQR genes, and bacterial community composition in sediment and water samples in the Liuxi River, China. Antibiotics concentrations were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. ARGs abundances were quantified by a culture-independent method. Bacterial community composition was analyzed by metagenomic approach based on Ion Torrent Personal Genome Machine platform. Antibiotics concentrations were at the levels of 1.19 to 622 ug kg-1 in sediment samples and below the limit of detection to 127 ng L-1 in water samples. Relative abundances (ARGs copies/16S rRNA gene copies of detected ARGs were at the range of 10-5 to 10-2. The dominant phyla were Proteobacteria, Bacteroidetes and Verrucomicrobia in sediment samples, and were Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The results indicated that the river environment was contaminated by antibiotics and may be as a reservoir of ARGs. This study provided quantitative data on antibiotics, ARGs and bacterial community composition in the Liuxi River, a geographical location different from the reported studies.

  13. Conjunctival bacterial flora and antibiotic resistance pattern in patients undergoing cataract surgery

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    Arantes Tiago Eugênio Faria e

    2006-01-01

    Full Text Available PURPOSE: To evaluate the conjunctival bacterial flora and its antibiotic resistance pattern in eyes of patients undergoing cataract surgery. METHODS: From August to October 2004, 50 patients undergoing cataract surgery in the "Fundação Altino Ventura", Recife, Brazil, were prospectively evaluated. Conjunctival material was obtained on the day of surgery, before the application of topical anesthetic, antibiotic or povidone-iodine. The collected material was inoculated and bacterioscopic analysis was carried out. In the cases where there was bacterial growth, antibiotic susceptibility tests and cultures, for isolation and identification of the bacteria, were performed. RESULTS: Of the 50 eyes, 43 (86.0% had positive cultures. The coagulase-negative Staphylococcus (CNS, found in 27 (54.0% eyes, was the most frequent organism. More than 90% of the isolates of this bacterium were susceptible to cephalotin, vancomycin, chloramphenicol, ofloxacin and gatifloxacin; 70 to 90% were susceptible to gentamicin, cefotaxime, oxacillin and ciprofloxacin; and less than 70% were sensible to neomycin. Four (10.5% of the bacterial isolates were resistant to four or more antibiotics, two of them were CNS. CONCLUSION: The most frequent bacterium in the conjunctival flora is the coagulase-negative Staphylococcus. The isolates of this organism showed low susceptibility rate to neomycin, and high susceptibility rates to cephalotin, vancomycin, chloramphenicol, ofloxacin and gatifloxacin.

  14. Isolation and Characterization of Nickel Uptake by Nickel Resistant Bacterial Isolate (NiRBI)

    Institute of Scientific and Technical Information of China (English)

    JAGDISH S PATEL; PRERNA C PATEL; KIRAN KALIA

    2006-01-01

    Bioremediation technology has gained importance because microbes could be the convenient source of bio-absorption/bioaccumulation of metals from effluent streams. Methods The nickel-resistant bacterial isolates (NiRBI)were selected from various bacterial isolates from industrial effluent and grown in nutrient broth containing different concentrations of nickel sulfate (0.3-3.0 mmol/L) and their capability of accumulating metal from the medium. Results Well-defined growth of NiRBI was observed in the medium containing up to 2.5 mmol/L of nickel. The isolate was identified using 16S rRNA and closely related to Pseudomonas fragi. Maximum accumulation of nickel (0.59 mg/g dry weight of bacterial cells) was observed when NiRBI was grown in media containing 2 mmol/L of nickel. The protein profile of the NiRBI cellular extract by SDS-PAGE showed two metal stress-induced proteins of molecular weight 48 KD and 18 KD with a simultaneous down regulation of four proteins of 46.7 KD, 42.2 KD, 19.7 KD, and 4.0 KD. Conclusion 48 KD and 18 KD proteins play a role in metal resistance mechanism by NiRBI.

  15. Pipecolic acid enhances resistance to bacterial infection and primes salicylic acid and nicotine accumulation in tobacco.

    Science.gov (United States)

    Vogel-Adghough, Drissia; Stahl, Elia; Návarová, Hana; Zeier, Juergen

    2013-11-01

    Distinct amino acid metabolic pathways constitute integral parts of the plant immune system. We have recently identified pipecolic acid (Pip), a lysine-derived non-protein amino acid, as a critical regulator of systemic acquired resistance (SAR) and basal immunity to bacterial infection in Arabidopsis thaliana. In Arabidopsis, Pip acts as an endogenous mediator of defense amplification and priming. For instance, Pip conditions plants for effective biosynthesis of the phenolic defense signal salicylic acid (SA), accumulation of the phytoalexin camalexin, and expression of defense-related genes. Here, we show that tobacco plants respond to leaf infection by the compatible bacterial pathogen Pseudomonas syringae pv tabaci (Pstb) with a significant accumulation of several amino acids, including Lys, branched-chain, aromatic, and amide group amino acids. Moreover, Pstb strongly triggers, alongside the biosynthesis of SA and increases in the defensive alkaloid nicotine, the production of the Lys catabolites Pip and α-aminoadipic acid. Exogenous application of Pip to tobacco plants provides significant protection to infection by adapted Pstb or by non-adapted, hypersensitive cell death-inducing P. syringae pv maculicola. Pip thereby primes tobacco for rapid and strong accumulation of SA and nicotine following bacterial infection. Thus, our study indicates that the role of Pip as an amplifier of immune responses is conserved between members of the rosid and asterid groups of eudicot plants and suggests a broad practical applicability for Pip as a natural enhancer of plant disease resistance.

  16. Phenotypic and genotypic variation among Capsicum annuum recombinant inbred lines resistant to bacterial spot.

    Science.gov (United States)

    Moreira, S O; Rodrigues, R; Oliveira, H S; Medeiros, A M; Sudré, C P; Gonçalves, L S A

    2013-04-17

    A breeding program carried out under Brazilian growing conditions to obtain Capsicum annuum cultivars with disease resistance to bacterial spot (BS) produced 8 promising recombinant inbred lines (RILs). The present study aimed to characterize these RILs using phenotypic descriptors and molecular markers (inter-simple sequence repeat) and to confirm their resistance to BS. Twenty-two phenotypic descriptors and 15 inter-simple sequence repeat primers were used to characterize the RILs. The parent, UENF 1381, which is resistant to BS, and 'Casca Dura Ikeda', a traditional cultivar, were used as standards. Variability among genotypes was observed considering either binary or multicategorical characteristics, such as fruit length, fruit diameter, and fruit longitudinal and transversal section. Such variability in fruit traits can be exploited to develop new genotypes with BS resistance for various types of market consumption. RILs numbered 1, 3, and 6 were the most homogenous, whereas those coded 2, 5, 8, and 11 had the same level of heterogeneity as that observed in 'Casca Dura Ikeda'. Molecular analysis clustered the genotypes into 5 groups, with RILs 1, 2, 3, and 5 allocated in isolated groups. RILs 1, 2, 6, and 8 confirmed resistance to BS. Considering homogeneity level and BS resistance, RILs 1 and 6 were suitable for use as pre-cultivars in final tests to register and release two new C. annuum cultivars.

  17. Bacterial resistance and human microecology%细菌耐药与人体微生态

    Institute of Scientific and Technical Information of China (English)

    郑焙文; 李兰娟

    2016-01-01

    细菌耐药是全球严重的公共卫生问题,我国是抗菌药物不合理应用和细菌耐药情况较为严重的国家之一,“后抗生素”时代可能很快会成为现实。近年来随着微生态学研究的快速发展,人体微生态与细菌耐药之间的关联研究受到极大的关注,以微生态学的视角推动多学科交叉研究,创新细菌耐药研究的新技术,揭示病原菌的群体耐药作用机制和进化规律成为可能。此文就细菌耐药及微生态学相关学科进展进行介绍,并从微生态学的角度对细菌耐药领域下一步的研究方向和研究思路进行展望。%Antibiotic resistance is a serious global public health problem, and China is one of the countries with the serious problem of irrational antibiotic use and bacterial drug resistance.The world is headed for a post-antibiotic era.With the rapid development of microecology, microbiota has been linked with antibiotic resistance.From microecological point of view, it is possible for researchers in different fields to innovate new techniques for bacterial drug resistance, and to explore the evolution of pathogenic bacteria as well as the mechanism of their resistance to antibacterial agents.This paper reviews the research progress in bacterial resistance and microecology, and prospects the future research needs that should be prioritized to tackle antibiotic resistance.

  18. Seed defensins of barnyard grass Echinochloa crusgalli (L.) Beauv.

    Science.gov (United States)

    Odintsova, Tatyana I; Rogozhin, Eugene A; Baranov, Yurij; Musolyamov, Alexander Kh; Yalpani, Nasser; Egorov, Tsezi A; Grishin, Eugene V

    2008-01-01

    From the annual weed barnyard grass Echinochloa crusgalli (L.) Beauv., two novel defensins Ec-AMP-D1 and Ec-AMP-D2 that differ by a single amino acid substitution were isolated by a combination of different chromatographic procedures. Both defensins were active against several phytopathogenic fungi and the oomycete Phytophthora infestans at micromolar concentrations. The Ec-AMP-D1 showed higher activity against the oomycete than Ec-AMP-D2. The comparison of the amino acid sequences of the antifungal E. crusgalli defensins with those of earlier characterized T. kiharae defensins [T.I. Odintsova, Ts.A. Egorov, A.Kh. Musolyamov, M.S. Odintsova, V.A. Pukhalsky, E.V. Grishin, Seed defensins from T. kiharae and related species: genome localization of defensin-encoding genes, Biochimie, 89 (2007) 605-612.] that were devoid of substantial antifungal activity point to the C-terminal region of the molecule as the main determinant of the antifungal activity of E. crusgalli defensins.

  19. Comparative Resistance of AH26 and a New Sealer Prototype to a Bacterial Challenge

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    Derek Duggan

    2012-01-01

    Full Text Available Objective. This study compared the leakage resistance of a New Sealer Prototype (NSP with a traditional sealer (AH 26 in Resilon-filled roots subjected to a bacterial challenge. Study Design. 41 roots were instrumented to ISO size 50 apically. Group 1 (=20 contained Resilon and AH 26 sealer and roots in group 2 (=21 contained Resilon and NSP. Roots were embedded in a dual-chamber model with the upper chamber containing Streptococcus mutans inoculum. Evidence of bacterial penetration was observed for 1 month. Fisher's Test was used to analyze the data. Results. 8 of 20 roots (40% in the AH 26 group demonstrated leakage whereas 3 of 21 roots (14% in the NSP group leaked. The difference in leakage rates was not statistically significant (=0.053. Conclusion. The traditional sealer (AH 26 demonstrated increased leakage rates compared to the New Sealer Prototype (NSP, but the difference did not reach statistical significance in this study.

  20. Proteomics as a tool for studying bacterial virulence and antimicrobial resistance

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    Francisco José Pérez -Llarena

    2016-03-01

    Full Text Available Proteomic studies have improved our understanding of the microbial world. The most recent advances in this field have helped us to explore aspects beyond genomics. For example, by studying proteins and their regulation, researchers now understand how some pathogenic bacteria have adapted to the lethal actions of antibiotics. Proteomics has also advanced our knowledge of mechanisms of bacterial virulence and some important aspects of how bacteria interact with human cells and, thus, of the pathogenesis of infectious diseases. This review article addresses these issues in some of the most important human pathogens. It also reports some applications of MALDI-TOF mass spectrometry that may be important for the diagnosis of bacterial resistance in clinical laboratories in the future. The reported advances will enable new diagnostic and therapeutic strategies to be developed in the fight against some of the most lethal bacteria affecting humans.

  1. Rapid Detection of Bacterial Antibiotic Resistance: Preliminary Evaluation of PCR Assays Targeting Tetracycline Resistance Genes

    Science.gov (United States)

    2007-08-01

    significant homologies over a wide range of species. The sequence of the Campylobacter jejuni tet(O) gene, used in this study as the core sequence...protection protein tet(O): M18896*, Campylobacter jejuni tet(O) gene; AY190525, Campylobacter jejuni plasmid pCjA13 tetracycline resistance protein tet(O

  2. Bacterial diversity and antibiotic resistance in water habitats: searching the links with the human microbiome.

    Science.gov (United States)

    Vaz-Moreira, Ivone; Nunes, Olga C; Manaia, Célia M

    2014-07-01

    Water is one of the most important bacterial habitats on Earth. As such, water represents also a major way of dissemination of bacteria between different environmental compartments. Human activities led to the creation of the so-called urban water cycle, comprising different sectors (waste, surface, drinking water), among which bacteria can hypothetically be exchanged. Therefore, bacteria can be mobilized between unclean water habitats (e.g. wastewater) and clean or pristine water environments (e.g. disinfected and spring drinking water) and eventually reach humans. In addition, bacteria can also transfer mobile genetic elements between different water types, other environments (e.g. soil) and humans. These processes may involve antibiotic resistant bacteria and antibiotic resistance genes. In this review, the hypothesis that some bacteria may share different water compartments and be also hosted by humans is discussed based on the comparison of the bacterial diversity in different types of water and with the human-associated microbiome. The role of such bacteria as potential disseminators of antibiotic resistance and the inference that currently only a small fraction of the clinically relevant antibiotic resistome may be known is discussed.

  3. Effects of Biochar Amendment on Tomato Bacterial Wilt Resistance and Soil Microbial Amount and Activity

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    Yang Lu

    2016-01-01

    Full Text Available Bacterial wilt is a serious soilborne disease of Solanaceae crops which is caused by Ralstonia solanacearum. The important role of biochar in enhancing disease resistance in plants has been verified; however, the underlying mechanism remains not fully understood. In this study, two different biochars, made from peanut shell (BC1 and wheat straw (BC2, were added to Ralstonia solanacearum-infected soil to explore the interrelation among biochar, tomato bacterial wilt, and soil microbial properties. The results showed that both BC1 and BC2 treatments significantly reduced the disease index of bacterial wilt by 28.6% and 65.7%, respectively. The populations of R. solanacearum in soil were also significantly decreased by biochar application. Ralstonia solanacearum infection significantly reduced the densities of soil bacteria and actinomycetes and increased the ratio of soil fungi/bacteria in the soil. By contrast, BC1 and BC2 addition to pathogen-infected soil significantly increased the densities of soil bacteria and actinomycetes but decreased the density of fungi and the ratios of soil fungi/bacteria and fungi/actinomycetes. Biochar treatments also increased soil neutral phosphatase and urease activity. Furthermore, higher metabolic capabilities of microorganisms by biochar application were found at 96 and 144 h in Biolog EcoPlates. These results suggest that both peanut and wheat biochar amendments were effective in inhibiting tomato bacterial wilt caused by R. solanacearum. The results suggest a relationship between the disease resistance of the plants and the changes in soil microbial population densities and activity.

  4. Enhanced Disease Susceptibility1 Mediates Pathogen Resistance and Virulence Function of a Bacterial Effector in Soybean.

    Science.gov (United States)

    Wang, Jialin; Shine, M B; Gao, Qing-Ming; Navarre, Duroy; Jiang, Wei; Liu, Chunyan; Chen, Qingshan; Hu, Guohua; Kachroo, Aardra

    2014-05-28

    Enhanced disease susceptibility1 (EDS1) and phytoalexin deficient4 (PAD4) are well-known regulators of both basal and resistance (R) protein-mediated plant defense. We identified two EDS1-like (GmEDS1a/GmEDS1b) proteins and one PAD4-like (GmPAD4) protein that are required for resistance signaling in soybean (Glycine max). Consistent with their significant structural conservation to Arabidopsis (Arabidopsis thaliana) counterparts, constitutive expression of GmEDS1 or GmPAD4 complemented the pathogen resistance defects of Arabidopsis eds1 and pad4 mutants, respectively. Interestingly, however, the GmEDS1 and GmPAD4 did not complement pathogen-inducible salicylic acid accumulation in the eds1/pad4 mutants. Furthermore, the GmEDS1a/GmEDS1b proteins were unable to complement the turnip crinkle virus coat protein-mediated activation of the Arabidopsis R protein Hypersensitive reaction to Turnip crinkle virus (HRT), even though both interacted with HRT. Silencing GmEDS1a/GmEDS1b or GmPAD4 reduced basal and pathogen-inducible salicylic acid accumulation and enhanced soybean susceptibility to virulent pathogens. The GmEDS1a/GmEDS1b and GmPAD4 genes were also required for Resistance to Pseudomonas syringae pv glycinea2 (Rpg2)-mediated resistance to Pseudomonas syringae. Notably, the GmEDS1a/GmEDS1b proteins interacted with the cognate bacterial effector AvrA1 and were required for its virulence function in rpg2 plants. Together, these results show that despite significant structural similarities, conserved defense signaling components from diverse plants can differ in their functionalities. In addition, we demonstrate a role for GmEDS1 in regulating the virulence function of a bacterial effector.

  5. New insights in the bacterial spore resistance to extreme terrestrial and extraterrestrial factors

    Science.gov (United States)

    Moeller, Ralf; Horneck, Gerda; Reitz, Guenther

    Based on their unique resistance to various space parameters, Bacillus endospores are one of the model systems used for astrobiological studies. The extremely high resistance of bacterial endospores to environmental stress factors has intrigued researchers since long time and many characteristic spore features, especially those involved in the protection of spore DNA, have already been uncovered. The disclosure of the complete genomic sequence of Bacillus subtilis 168, one of the often used astrobiological model system, and the rapid development of tran-scriptional microarray techniques have opened new opportunities of gaining further insights in the enigma of spore resistance. Spores of B. subtilis were exposed to various extreme ter-restrial and extraterrestrial stressors to reach a better understanding of the DNA protection and repair strategies, which them to cope with the induced DNA damage. Following physical stress factors of environmental importance -either on Earth or in space -were selected for this thesis: (i) mono-and polychromatic UV radiation, (ii) ionizing radiation, (iii) exposure to ultrahigh vacuum; and (iv) high shock pressures simulating meteorite impacts. To reach a most comprehensive understanding of spore resistance to those harsh terrestrial or simulated extraterrestrial conditions, a standardized experimental protocol of the preparation and ana-lyzing methods was established including the determination of the following spore responses: (i) survival, (ii) induced mutations, (iii) DNA damage, (iv) role of different repair pathways by use of a set of repair deficient mutants, and (v) transcriptional responses during spore germi-nation by use of genome-wide transcriptome analyses and confirmation by RT-PCR. From this comprehensive set of data on spore resistance to a variety of environmental stress parameters a model of a "built-in" transcriptional program of bacterial spores in response to DNA damaging treatments to ensure DNA restoration

  6. In vitro evaluation of the risk of inducing bacterial resistance to disinfection treatment with photolysis of hydrogen peroxide.

    Directory of Open Access Journals (Sweden)

    Hiroyo Ikai

    Full Text Available The purpose of the present study was to evaluate the risk of inducing bacterial resistance to disinfection treatment with photolysis of H2O2 and comparing this with existing antibacterial agents. We tested seven antibacterial agents, including amoxicillin, cefepime hydrochloride, erythromycin, ofloxacin, clindamycin hydrochloride, ciprofloxacin hydrochloride, and minocycline hydrochloride, as positive controls for validation of the assay protocol. For all of the agents tested, at least one of the four bacterial species (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Streptococcus salivarius was resistant to these agents by repeated exposure to subinhibitory concentrations of the agents up to 10 times. In contrast, antibacterial activity against any of the bacterial species tested (S. aureus, E. faecalis, E. coli, S. salivarius, Pseudomonas aeruginosa, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans was not affected by repeated exposure to the disinfection treatment up to 40 times. This finding suggested that the risk of inducing bacterial resistance by disinfection treatment was low. The active ingredient of this disinfection treatment is hydroxyl radicals generated by photolysis of H2O2. Therefore, hydroxyl radicals interact with several cell structures and different metabolic pathways in microbial cells, probably resulting in a lack of development of bacterial resistance. In conclusion, disinfection treatment with photolysis of H2O2 appears to be a potential alternative for existing antimicrobial agents in terms of a low risk of inducing bacterial resistance.

  7. In vitro evaluation of the risk of inducing bacterial resistance to disinfection treatment with photolysis of hydrogen peroxide.

    Science.gov (United States)

    Ikai, Hiroyo; Odashima, Yu; Kanno, Taro; Nakamura, Keisuke; Shirato, Midori; Sasaki, Keiichi; Niwano, Yoshimi

    2013-01-01

    The purpose of the present study was to evaluate the risk of inducing bacterial resistance to disinfection treatment with photolysis of H2O2 and comparing this with existing antibacterial agents. We tested seven antibacterial agents, including amoxicillin, cefepime hydrochloride, erythromycin, ofloxacin, clindamycin hydrochloride, ciprofloxacin hydrochloride, and minocycline hydrochloride, as positive controls for validation of the assay protocol. For all of the agents tested, at least one of the four bacterial species (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Streptococcus salivarius) was resistant to these agents by repeated exposure to subinhibitory concentrations of the agents up to 10 times. In contrast, antibacterial activity against any of the bacterial species tested (S. aureus, E. faecalis, E. coli, S. salivarius, Pseudomonas aeruginosa, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans) was not affected by repeated exposure to the disinfection treatment up to 40 times. This finding suggested that the risk of inducing bacterial resistance by disinfection treatment was low. The active ingredient of this disinfection treatment is hydroxyl radicals generated by photolysis of H2O2. Therefore, hydroxyl radicals interact with several cell structures and different metabolic pathways in microbial cells, probably resulting in a lack of development of bacterial resistance. In conclusion, disinfection treatment with photolysis of H2O2 appears to be a potential alternative for existing antimicrobial agents in terms of a low risk of inducing bacterial resistance.

  8. BACTERIAL CAUSES OF LOWER RESPIRATORY TRACT INFECTIONS IN PATIENTS ATTENDING CENTRAL REFERRAL HOSPITAL, GANGTOK WITH REFERENCE TO ANTIBIOTIC RESISTANCE PATTERN

    OpenAIRE

    Priyanka Paul; Tukaram Prabhu

    2013-01-01

    ABSTRACT: BACKGROUND: There is inadequate information from India on various lower respiratory tract pathogens and their resistance pattern in hospital settings. The present study was undertaken to see the bacteriological profile an d the antibiotic resistance pattern of the isolates causing LRTI from this geographic region. OBJECTIVE: To identify and characterize bacterial pathogens causing community acquired and hospital acquired infections with reference to ant...

  9. Bacterial Flora from Healthy Clarias gariepinus and their Antimicrobial Resistance Pattern

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    M.O. Efuntoye

    2012-06-01

    Full Text Available The antibiotic resistance of bacteria isolated from Clarias gariepinus from 3 farms in Ago-Iwoye, Nigeria was investigated. Morphological and biochemical characteristics of isolates revealed that majority of the bacteria belonged to the family Enterobacteriaceae. Staphylococcus aureus and Pseudomonas aeruginosa were also recovered. E. coli strains were highly resistant to ampicillin, chloramphenicol and oxytetracycline (82.4%. Majority of the Pseudomonas aeruginosa were resistant to ampicillin (63.6%, amoxycillin (54.5%, nalidixic acid (63.6% and oxytetracycline (72.7%, whereas most of the Salmonella spp. were resistant to erythromycin (85.7%, gentamycin (71.4%, amoxicillin (57.1%, chloramphenicol (57.1% and sulphamethoxazole (57.1%. All isolates were highly sensitive to ciprofloxacin, novobiocin and ofloxacin. While the presence of potentially pathogenic bacterial species as observed in the study may not present a serious human health hazard because of heat treatment accorded fish before consumption, the presence of antibiotic resistant strains should not be ignored because of the potential for horizontal gene transfer in the food chain.

  10. Bacterial resistance to complement killing mediated by the Ail protein of Yersinia enterocolitica.

    OpenAIRE

    Bliska, J B; Falkow, S

    1992-01-01

    Ail is a 17-kDa outer membrane Yersinia protein that mediates bacterial attachment to, and invasion of, cultured epithelial cells. We report here an alternative role for Ail in the pathogenesis of Yersinia infection. We found that Escherichia coli HB101 harboring the 4-kilobase recombinant ail clone pVM102 were highly resistant to killing in up to 50% normal human serum. A 674-base-pair fragment of DNA from pVM102, which encodes the ail gene, was inserted into pUC18 and shown to promote full ...

  11. Retrocyclins neutralize bacterial toxins by potentiating their unfolding.

    Science.gov (United States)

    Kudryashova, Elena; Seveau, Stephanie; Lu, Wuyuan; Kudryashov, Dmitri S

    2015-04-15

    Defensins are a class of immune peptides with a broad range of activities against bacterial, fungal and viral pathogens. Besides exerting direct anti-microbial activity via dis-organization of bacterial membranes, defensins are also able to neutralize various unrelated bacterial toxins. Recently, we have demonstrated that in the case of human α- and β-defensins, this later ability is achieved through exploiting toxins' marginal thermodynamic stability, i.e. defensins act as molecular anti-chaperones unfolding toxin molecules and exposing their hydrophobic regions and thus promoting toxin precipitation and inactivation [Kudryashova et al. (2014) Immunity 41, 709-721]. Retrocyclins (RCs) are humanized synthetic θ-defensin peptides that possess unique cyclic structure, differentiating them from α- and β-defensins. Importantly, RCs are more potent against some bacterial and viral pathogens and more stable than their linear counterparts. However, the mechanism of bacterial toxin inactivation by RCs is not known. In the present study, we demonstrate that RCs facilitate unfolding of bacterial toxins. Using differential scanning fluorimetry (DSF), limited proteolysis and collisional quenching of internal tryptophan fluorescence, we show that hydrophobic regions of toxins normally buried in the molecule interior become more exposed to solvents and accessible to proteolytic cleavage in the presence of RCs. The RC-induced unfolding of toxins led to their precipitation and abrogated activity. Toxin inactivation by RCs was strongly diminished under reducing conditions, but preserved at physiological salt and serum concentrations. Therefore, despite significant structural diversity, α-, β- and θ-defensins employ similar mechanisms of toxin inactivation, which may be shared by anti-microbial peptides from other families.

  12. Focal Targeting of the Bacterial Envelope by Antimicrobial Peptides

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    Rafi eRashid

    2016-06-01

    Full Text Available Antimicrobial peptides (AMPs are utilized by both eukaryotic and prokaryotic organisms. AMPs such as the human beta defensins, human neutrophil peptides, human cathelicidin, and many bacterial bacteriocins are cationic and capable of binding to anionic regions of the bacterial surface. Cationic AMPs (CAMPs target anionic lipids (e.g. phosphatidylglycerol (PG and cardiolipins (CL in the cell membrane and anionic components (e.g. lipopolysaccharide (LPS and lipoteichoic acid (LTA of the cell envelope. Bacteria have evolved mechanisms to modify these same targets in order to resist CAMP killing, e.g. lysinylation of PG to yield cationic lysyl-PG and alanylation of LTA. Since CAMPs offer a promising therapeutic alternative to conventional antibiotics, which are becoming less effective due to rapidly emerging antibiotic resistance, there is a strong need to improve our understanding about the AMP mechanism of action. Recent literature suggests that AMPs often interact with the bacterial cell envelope at discrete foci. Here we review recent AMP literature, with an emphasis on focal interactions with bacteria, including (1 CAMP disruption mechanisms, (2 delocalization of membrane proteins and lipids by CAMPs, and (3 CAMP sensing systems and resistance mechanisms. We conclude with new approaches for studying the bacterial membrane, e.g., lipidomics, high resolution imaging and non-detergent-based membrane domain extraction.

  13. Comparison of Metals and Tetracycline as Selective Agents for Development of Tetracycline Resistant Bacterial Communities in Agricultural Soil.

    Science.gov (United States)

    Song, Jianxiao; Rensing, Christopher; Holm, Peter E; Virta, Marko; Brandt, Kristian K

    2017-03-07

    Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)select for tetracycline resistance in bacterial communities. Soil microcosms were established by amending agricultural soil with known levels of Cu, Zn, or tetracycline known to represent commonly used metals and antibiotics for pig farming. Soil bacterial growth dynamics and bacterial community-level tetracycline resistance were determined using the [(3)H]leucine incorporation technique, whereas soil Cu, Zn, and tetracycline exposure were quantified by a panel of whole-cell bacterial bioreporters. Tetracycline resistance increased significantly in soils containing environmentally relevant levels of Cu (≥365 mg kg(-1)) and Zn (≥264 mg kg(-1)) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg(-1)). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself.

  14. Novel bacterial metabolite merochlorin A demonstrates in vitro activity against multi-drug resistant methicillin-resistant Staphylococcus aureus.

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    George Sakoulas

    Full Text Available BACKGROUND: We evaluated the in vitro activity of a merochlorin A, a novel compound with a unique carbon skeleton, against a spectrum of clinically relevant bacterial pathogens and against previously characterized clinical and laboratory Staphylococcus aureus isolates with resistance to numerous antibiotics. METHODS: Merochlorin A was isolated and purified from a marine-derived actinomycete strain CNH189. Susceptibility testing for merochlorin A was performed against previously characterized human pathogens using broth microdilution and agar dilution methods. Cytotoxicity was assayed in tissue culture assays at 24 and 72 hours against human HeLa and mouse sarcoma L929 cell lines. RESULTS: The structure of as new antibiotic, merochlorin A, was assigned by comprehensive spectroscopic analysis. Merochlorin A demonstrated in vitro activity against Gram-positive bacteria, including Clostridium dificile, but not against Gram negative bacteria. In S. aureus, susceptibility was not affected by ribosomal mutations conferring linezolid resistance, mutations in dlt or mprF conferring resistance to daptomycin, accessory gene regulator knockout mutations, or the development of the vancomycin-intermediate resistant phenotype. Merochlorin A demonstrated rapid bactericidal activity against MRSA. Activity was lost in the presence of 20% serum. CONCLUSIONS: The unique meroterpenoid, merochlorin A demonstrated excellent in vitro activity against S. aureus and C. dificile and did not show cross-resistance to contemporary antibiotics against Gram positive organisms. The activity was, however, markedly reduced in 20% human serum. Future directions for this compound may include evaluation for topical use, coating biomedical devices, or the pursuit of chemically modified derivatives of this compound that retain activity in the presence of serum.

  15. Two-component system YvqEC-dependent bacterial resistance against vancomycin in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Shumeng; Hu, Yimin; Fan, Qingyun; Wang, Xun; He, Jin

    2015-08-01

    YvqEC is one of the two-component signal transduction systems that may respond to cell envelope stress and enable cells to adjust multiple cellular functions. It consists of a histidine kinase YvqE and a response regulator YvqC. In this study, we separately constructed a single gene mutant ΔyvqE and a double gene mutant ΔyvqEC in Bacillus thuringiensis BMB171 through a homing endonucleases I-SceI mediated markerless gene deletion method. We found that the deletion of either yvqE or yvqEC weakened the resistance of B. thuringiensis against vancomycin. We also identified nine operons that may be involved in the cellular metabolism regulated by YvqC. This study not only enriches our understanding of bacterial resistance mechanisms against vancomycin, but also helps investigate the functions of YvqEC.

  16. Prevalence of antibacterial resistant bacterial contaminants from mobile phones of hospital inpatients

    Directory of Open Access Journals (Sweden)

    B. Vinod Kumar

    2014-10-01

    Full Text Available Mobile phones contaminated with bacteria may act as fomites. Antibiotic resistant bacterial contamination of mobile phones of inpatients was studied. One hundred and six samples were collected from mobile phones of patients admitted in various hospitals in Jazan province of Saudi Arabia. Eighty-nine (83.9% out of 106 mobile phones were found to be contaminated with bacteria. Fifty-two (49.0% coagulase-negative Staphylococcus, 12 (11.3% Staphylococcus aureus, 7 (6.6% Enterobacter cloacae, 3 (2.83% Pseudomonas stutzeri, 3 (2.83% Sphingomonas paucimobilis, 2 (1.8% Enterococcus faecalis and 10 (9.4% aerobic spore bearers were isolated. All the isolated bacteria were found to be resistant to various antibiotics. Hence, regular disinfection of mobile phones of hospital inpatients is advised.

  17. Production of bacterial blight resistant lines from somatic hybridization between Oryza sativa L. and Oryza meyeriana L.

    Institute of Scientific and Technical Information of China (English)

    严成其; 钱凯先; 薛刚平; 吴忠长; 陈跃磊; 颜秋生; 张雪琴; 吴平

    2004-01-01

    Novel bacterial blight (BB) resistance gene(s) for rice was (were) introduced into a cultivated japonica rice variety Oryza sativa (cv. 8411), via somatic hybridization using the wild rice Oryza meyeriana as the donor of the resistance gene(s). Twenty-nine progenies of somatically hybridized plants were obtained. Seven somatically hybridized plants and their parents were used for AFLP (amplified fragment length polymorphism) analysis using 8 primer pairs. Results confirmed that these plants were somatic hybrids containing the characteristic bands of both parents. The morphology of the regenerated rice showed characters of both O.sativa and O.meyeriana. Two somatic hybrids showed highest BB resistance and the other 8 plants showed moderate resistance. The new germplasms with highest resistance have been used in the rice breeding program for the improvement of bacterial blight resistance.

  18. Production of bacterial blight resistant lines from somatic hybridization between Oryza sativa L.and Oryza meyeriana L.

    Institute of Scientific and Technical Information of China (English)

    严成其; 钱凯先; 薛刚平; 吴忠长; 陈跃磊; 颜秋生; 张雪琴; 吴平

    2004-01-01

    Novel bacterial blight (BB) resistance gene(s) for rice was (were) introduced into a cultivated japonica rice variety Oryza sativa (cv. 8411), via somatic hybridization using the wild rice Oryza meyeriana as the donor of the resistance gene(s). Twenty-nine progenies of somatically hybridized plants were obtained. Seven somatically hybridized plants and their parents were used for AFLP (amplified fragment length polymorphism) analysis using 8 primer pairs. Results confirmed that these plants were somatic hybrids containing the characteristic bands of both parents. The morphology of the regenerated rice showed characters of both O. sativa and O. meyeriana. Two somatic hybrids showed highest BB resistance and the other 8 plants showed moderate resistance. The new germplasms with highest resistance have been used in the rice bfeeding program for the improvement of bacterial blight resistance.

  19. Ultrastructural immunolocalization of beta-defensin-27 in granulocytes of the dermis and wound epidermis of lizard suggests they contribute to the anti-microbial skin barrier.

    Science.gov (United States)

    Alibardi, Lorenzo

    2013-12-01

    The high resistance to infections in lizard wounds suggests that these reptiles possess effective antimicrobial peptides in their tissues. The present immunocytochemical study shows the cellular localization of beta-defensin 27 in tail tissues and in the blood, a defensin previously identified in the lizard Anolis carolinensis through biomolecular methods. Beta-defensin-27 immunoreactivity is only observed in some large granules mainly contained in heterophilic granulocytes that are sparse within the dermis of the skin or in the isolated blood. This peptide is absent in other cell types of the skin, in keratinocytes and in subdermal muscle tissue of the tail in normal conditions. Pre-corneous keratinocytes of the regenerating tail epidermis are unlabeled or show a weak labeling for the peptide only in sparse cytoplasmic areas or in the extracellular spaces among corneocytes of the wound and regenerating epidermis. The study suggests that beta-defensin 27 is normally stored in granulocytes present in the blood or in connective tissues while in the epidermis keratinocytes do not show the presence of this peptide unless these cells are stimulated from injury to produce and likely release beta-defensins.

  20. Exploiting bacterial drug resistance: a single construct for the diagnosis and treatment of drug resistant infections

    Science.gov (United States)

    Sallum, Ulysses W.; Zheng, Xiang; Verma, Sarika; Hasan, Tayyaba

    2009-06-01

    β-lactamase enzyme-activated photosensitizer (β-LEAP). We aim to exploit drug resistance mechanisms to selectively release photosensitizers (PSs) for a specific photodynamic antimicrobial effect and reduced host tissue damage. Consequently, the fluorescence emission intensity of the PSs increases and allows for the detection of enzyme activity. In this work we sought to evaluate β-LEAP for use as a sensitive molecular probe. We have reported the enzyme specific antibacterial action of β-LEAP. Here we report the use of β-LEAP for the rapid functional definition of a β-lactamase.

  1. Interactions of antibiotics and methanolic crude extracts of Afzelia Africana (Smith.) against drug resistance bacterial isolates.

    Science.gov (United States)

    Aiyegoro, Olayinka; Adewusi, Adekanmi; Oyedemi, Sunday; Akinpelu, David; Okoh, Anthony

    2011-01-01

    Infection due to multidrug resistance pathogens is difficult to manage due to bacterial virulence factors and because of a relatively limited choice of antimicrobial agents. Thus, it is imperative to discover fresh antimicrobials or new practices that are effective for the treatment of infectious diseases caused by drug-resistant microorganisms. The objective of this experiment is to investigate for synergistic outcomes when crude methanolic extract of the stem bark of Afzelia africana and antibiotics were combined against a panel of antibiotic resistant bacterial strains that have been implicated in infections. Standard microbiological protocols were used to determine the minimum inhibitory concentrations (MICs) of the extract and antibiotics, as well as to investigate the effect of combinations of the methanolic extract of A. africana stem bark and selected antibiotics using the time-kill assay method. The extract of Afzelia africana exhibited antibacterial activities against both Gram-negative and Gram-positive bacteria made up of environmental and standard strains at a screening concentration of 5 mg/mL. The MICs of the crude extracts and the antibiotics varied between 1 μg/mL and 5.0 mg/mL. Overall, synergistic response constituted about 63.79% of all manner of combinations of extract and antibiotics against all test organisms; antagonism was not detected among the 176 tests carried out. The extract from A. africana stem bark showed potentials of synergy in combination with antibiotics against strains of pathogenic bacteria. The detection of synergy between the extract and antibiotics demonstrates the potential of this plant as a source of antibiotic resistance modulating compounds.

  2. Seasonal variations in bacterial communities and antibiotic-resistant strains associated with green bottle flies (Diptera: Calliphoridae).

    Science.gov (United States)

    Wei, Ting; Ishida, Ryuichi; Miyanaga, Kazuhiko; Tanji, Yasunori

    2014-05-01

    Green bottle flies occur frequently around human environments in Japan. Many species of green bottle flies have been studied with regard to their importance in forensic examinations or clinical therapies, but the bacterial communities associated with this group of flies have not been comprehensively investigated. In this research, 454 pyrosequencing was used to reveal the bacterial communities in green bottle flies collected in different seasons. Meanwhile, the bacteria were screened with selective media and tested for antibiotic susceptibility. Samples collected in three different seasons harbored distinctive bacterial communities. The predominant genera associated with green bottles flies were Staphylococcus in spring, Ignatzschineria in summer, and Vagococcus, Dysgonomonas, and an unclassified Acetobacteraceae in autumn. An upward trend in bacterial community diversity was observed from spring to autumn. Changes in climatic conditions could be the cause of these seasonal variations in fly-associated bacterial communities. The species of isolated antibiotic-resistant bacteria also differed across seasons, but it was difficult to correlate seasonal changes in antibiotic-resistant bacteria with changes in whole communities. A number of multiple-antibiotic-resistant bacteria were isolated, and some of these strains were closely affiliated with pathogens such as Enterococcus faecalis and Enterococcus faecium, which could cause serious threats to public health. Overall, this research provided us with information about the composition and seasonality of bacterial communities in green bottle flies, and highlighted the risks of fly-mediated dissemination of antibiotic-resistant pathogens.

  3. Antibiotic Resistance Pattern Of Bacterial Pathogens Isolated From Poultry Manure Used To Fertilize Fish Ponds In New Bussa, Nigeria

    Directory of Open Access Journals (Sweden)

    Funso Omojowo

    2013-02-01

    Full Text Available This study was carried out to isolate and identify antibiotic resistant bacteria from poultry manure usually used for pond fertilization. Poultry manure from 120 Chickens in National Institute for Freshwater Fisheries Research (NIFFR integrated fish farms, New-Bussa, Nigeria was collected. Five bacterial pathogens; Salmonella typhi, Escherichia coli, Shigella dysenteriae, Staphylococcus aureus and Aeromonas hydrophila were isolated. Antibiotic susceptibility testing carried out using the disk diffusion technique. Antibiotics used were; ofloxacin, amoxicillin, tetracycline, ampicillin, erythromycin, gentamicin, nalidixic acid and chloramphenicol. All the isolated organisms were 100% sensitive to ofloxacin. The multiple resistance pattern revealed that 100% were resistant to tetracycline, 84.34% resistant to ampicillin, 76.68% resistant to amoxicillin, 66% resistant to chloramphenicol, 66% resistant to gentamicin, 29% resistant to erythromycin, 28.34% resistant to nalidixic acid. The risk posed by untreated poultry manure used in fish pond fertilization and the public health implications of these results were discussed.

  4. Characterization and functions of beta defensins in the epididymis

    Institute of Scientific and Technical Information of China (English)

    Susan H. Hall; Suresh Yenugu; Yashwanth Radhakrishnan; Maria Christina W. Avellar; Peter Petrusz; Frank S. French

    2007-01-01

    The epididymal β-defensins have evolved by repeated gene duplication and divergence to encode a family of proteins that provide direct protection against pathogens and also support the male reproductive tract in its primary function. Male tract defensins also facilitate recovery from pathogen attack. The β-defensins possess ancient conserved sequence and structural features widespread in multi-cellular organisms, suggesting fundamental roles in species survival. Primate SPAG11, the functional fusion of two ancestrally independent β-defensin genes, produces a large family of alternatively spliced transcripts that are expressed according to tissue-specific and species-specific constraints. The complexity of SPAG11 varies in different branches of mammalian evolution. Interactions of human SPAG11D with host proteins indicate involvement in multiple signaling pathways.

  5. Prevalence of plasmid mediated pesticide resistant bacterial assemblages in crop fields.

    Science.gov (United States)

    Umamaheswari, S; Murali, M

    2010-11-01

    Three crop fields namely paddy sugarcane and tomato exposed to bavistin [Methyl (1H-benzimidazol-2-yl) carbomate], monocrotophos[Dimethyl(E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] and kinado plus [(EZ)-2-chloro-3-dimethoxyphosphinoyloxy-X1, X1-diethylbut-2-enamide], respectively were chosen for the present investigation to know the bacterial population and degradation of pesticides. The chemical nature of the soil and water samples from the pesticide contaminated fields was analysed along with counting of the total heterotrophic bacteria (THB), Staphylococci and Enterococcci population. Mean calcium, phosphate and biological oxygen demand were maximum in tomato field water Field water recorded maximum phophate and silicate content, whereas, sugarcane field water elicited maximum dissolved oxygen content. On the other hand, available phosphate and exchangeable potassium were maximum is sugarcane field soil. Significant variations in the bacterial population were evident between the treatments in sugarcane field soil and tomato field water exposed to monocrotophos and kinado plus, respectively In addition, significant variations between THB, Staphlyococci and Enterococci population were also evinced in both the sugarcane andtomato fields. The dominant pesticide resistant bacteria, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeuroginosa harboured plasmids and the resistant trait observed were found to be plasmid borne.

  6.   Bloodstream Bacterial Pathogens and their Antibiotic Resistance Pattern in Dhahira Region, Oman

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    PP Geethanjali

    2011-07-01

    Full Text Available Objectives: To describe the epidemiological, clinical, microbiological characteristics and antimicrobial resistance pattern of Bloodstream infections in Dhahira region, Oman.Methods: Clinical data was collected from all patients with positive blood cultures for two years period. Standard laboratory methods were used for blood culture. Antibiotic sensitivity was tested using Kirby-Bauer disc diffusion method.Results: Of the 360 bacterial pathogens isolated from 348 patients, 57.8�0were gram-positive and 42.2�0were gram-negative. The common isolates were: Streptococcus species 76 (21.1� coagulase-negative Staphylococci 75 (20.8� Escherichia coli 43 (11.9� Staphylococcus aureus 41 (11.4� Overall, mortality was 21.3�0(74/348. Staphylococcus species (Staphylococcus aureus and CoNS were more commonly resistant to Trimethoprim/ Sulphamethoxazole (35.3�20and Penicillin (25.9� Streptococcus species were resistant to Trimethoprim/Sulphamethoxazole (39.1�20and Erythromycin (19.6�Conclusion: Bloodstream infections are important causes of morbidity and mortality in our patients, especially among chronically ill elderly adult males. Prescription of proven resistant antibiotics to suspected bacteremic patients needs attention in Dhahira region.

  7. Transgenic resistance confers effective field level control of bacterial spot disease in tomato.

    Directory of Open Access Journals (Sweden)

    Diana M Horvath

    Full Text Available We investigated whether lines of transgenic tomato (Solanum lycopersicum expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides.

  8. Evolution of the avian β-defensin and cathelicidin genes

    OpenAIRE

    Cheng, Yuanyuan; Prickett, Michael Dennis; Gutowska, Maria; Kuo, Richard; Belov, Katherine; Burt, David W.

    2015-01-01

    Background β-defensins and cathelicidins are two families of cationic antimicrobial peptides (AMPs) with a broad range of antimicrobial activities that are key components of the innate immune system. Due to their important roles in host defense against rapidly evolving pathogens, the two gene families provide an ideal system for studying adaptive gene evolution. In this study we performed phylogenetic and selection analyses on β-defensins and cathelicidins from 53 avian species representing 3...

  9. Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs

    Directory of Open Access Journals (Sweden)

    Geisla Mary Silva Soares

    2012-06-01

    Full Text Available Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of β-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections.

  10. Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs.

    Science.gov (United States)

    Soares, Geisla Mary Silva; Figueiredo, Luciene Cristina; Faveri, Marcelo; Cortelli, Sheila Cavalca; Duarte, Poliana Mendes; Feres, Magda

    2012-01-01

    Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole) and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of β-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections.

  11. [Purification and antimicrobial activity of human neutrophil defensins].

    Science.gov (United States)

    Qu, X; Wang, A

    1991-11-01

    Neutrophils are one of the weapons of host defenses against microbial infection. Their ability to kill the invading microorganisms depends on two principle mechanisms. One depends on production of reactive oxygen intermediates (ROI) by stimulated neutrophils, and the other depends on the delivery of antimicrobial contents of the neutrophils' cytoplasmic granules, oxygen-independent. The defensins have the highest concentration in the neutrophils, and the broadest antimicrobial spectrum, being capable of killing gram-positive and gram-negative bacteria, fungi and some envelope viruses. We purified human defensins from the neutrophils' granules by gel permeation chromatography and SDS-preparative acrylamide gel electrophoresis. The molecular weight of human defensins is between 3,000-4,000 daltons. After testing, C. neoformans was susceptible to these defensins. Under condition of 37 degrees C, pH 7.4 and low ionic strength, antifungal activity by human defensins was related to its concentration and incubating time. All of these illustrate that nonoxidative killing mechanism of neutrophils, especially the function of defensins is very important in host defenses.

  12. Bacterial Resistance---Challenges and Strategies%细菌耐药--挑战与对策

    Institute of Scientific and Technical Information of China (English)

    倪明; 田德英

    2016-01-01

    当前细菌耐药形势严峻。中国细菌耐药性监测网( CHINET)数据显示,革兰阴性菌分离率逐年上升,其中耐碳青霉烯类肠杆菌科细菌不仅检出率迅速上升,且多为广泛耐药菌株;广泛耐药甚至泛耐药非发酵菌,尤其是鲍曼不动杆菌的分离率仍较高,这些高度耐药的革兰阴性菌所致感染病死率高,已引起临床广泛关注。多重耐药革兰阳性菌方面,耐甲氧西林金黄色葡萄球菌和凝固酶阴性葡萄球菌平均检出率仍较高,耐万古霉素肠球菌分离率稳定,我国尚未分离出耐万古霉素金黄色葡萄球菌。了解本地细菌耐药的流行病学变化,才能根据患者病情制定恰当的用药策略。对于重症感染患者,及早使用抗菌药物、恰当降阶梯治疗可以降低病死率。合理的给药方式可使抗菌药物发挥最大作用,同时注意抗菌药物诱导内毒素释放等影响因素才能提高细菌感染性疾病治疗效果,降低不良反应。%Bacterial resistance to antibiotics is currently a serious health concern.According to the data from the surveil-lance of bacterial resistance in China ( CHINET) ,the isolation rates of gram-negative bacteria have been rising annually. Among the gram-negative organisms, the isolation rate of Carbapenem-resistant enterobacteriaceae, especially extensive drug-resistant strains,has been increasing rapidly.The isolation rate of extensive drug-resistant or pandrug-resistant non-fermenting bacteria,es-pecially Acinetobacter baumanii,is still relatively high.These extensive drug-resistant gram-negative bacteria cause high mortality, which has drawn great attention in clinical settings.On the part of multidrug-assistant gram-positive bacteria,the isolation rate of vancomycin-resistant enterococci remains stable but rates of methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci are still high.Staphylococcal strains have not yet

  13. Comparison of antibiotic resistance of bacterial agents associated in septicaemia in children and infants

    Directory of Open Access Journals (Sweden)

    Mohammad Kazem Sharifi Yazdi

    2014-05-01

    Full Text Available Background: Septicaemia is a leading cause of morbidity and mortality of infant’s and childerens espicially in first week of their life, both in developed and underdeveloped countries.The aim of this research was to study of bacterial agents causing septicaemia and to determine their antibiotic suseptibility patternes. Materials and Methods : This was a descriptive study, it was performed during eight months from October 2011 till May 2011.In total 216 blood culture samples of children suspected of septicaemia in children health centre hospital were send to the laboratory for investigation. The bacterial identification was carried out by culturing and conventional biomedical tests. The antibiotic sensitivity tests were performed by disk diffusion method. These data are analyzed by SPSS and the results Expressed as relative frequencies. Results: Out of 216 tested samples 55(25.6% were positive and 161 (74.54% negative. The dominated bacteria was Escherichia coli (31.42%, followed by Staphylococcus aureus (22.86 %, Klebsiella pneumonia (20%, Staphylococcus epidermidis (14.28%, Streptococcus pneumonia (2.86%, Salmonella typhi (2.86%, Enterobacter cloacae (2.86% and Stenotrophomonas maltophilia (2.86%. In general gram-negative bacteria were isolated more than gram-positive. Staphylococcus bacteria were more resistant to antibiotics than other isolated bacteria, and were 100% resistant to penicillin. The enterobacteriaceae were more sensitive to norfloxacin, amikacin, tobramycin, and they were 100% resistant to ampicillin. Conclusion: The results obtained in this study showed that gram-negative bacteria are more responsible in septicaemia in children ward, and norfloxacin is the more effective antibiotic in comparison with others.

  14. Enhanced Biofilm Formation and Increased Resistance to Antimicrobial Agents and Bacterial Invasion Are Caused by Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Burmølle, Mette; Webb, J.S.; Rao, D.

    2006-01-01

    Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated...... specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms....

  15. Antibiotic resistance among bacterial pathogens in Central Africa: a review of the published literature between 1955 and 2008.

    Science.gov (United States)

    Vlieghe, E; Phoba, M F; Tamfun, J J Muyembe; Jacobs, J

    2009-10-01

    A systematic review of the published literature on bacterial resistance in Central Africa between 1955 and 2008 was performed. Eighty-three publications from seven countries were retrieved, the majority presenting data on enteric and other gram-negative pathogens. Despite methodological limitations in many studies, alarming resistance rates are noted in nearly all pathogens. Of special concern are multidrug resistance in Shigella and Salmonella spp. and the emergence of meticillin-resistant Staphylococcus aureus, high-level penicillin-resistant Streptococcus pneumoniae and extended-spectrum beta-lactamases among gram-negative pathogens. These findings make clear that the Central African region shares the worldwide trend of increasing antimicrobial resistance and is in urgent need of sound surveillance based on competent and affordable microbiology to provide clear data on antimicrobial resistance. These data could enable redaction of local treatment guidelines and fuel national and regional policies to contain antimicrobial resistance.

  16. Metagenomic analysis of bacterial community composition and antibiotic resistance genes in a wastewater treatment plant and its receiving surface water.

    Science.gov (United States)

    Tang, Junying; Bu, Yuanqing; Zhang, Xu-Xiang; Huang, Kailong; He, Xiwei; Ye, Lin; Shan, Zhengjun; Ren, Hongqiang

    2016-10-01

    The presence of pathogenic bacteria and the dissemination of antibiotic resistance genes (ARGs) may pose big risks to the rivers that receive the effluent from municipal wastewater treatment plants (WWTPs). In this study, we investigated the changes of bacterial community and ARGs along treatment processes of one WWTP, and examined the effects of the effluent discharge on the bacterial community and ARGs in the receiving river. Pyrosequencing was applied to reveal bacterial community composition including potential bacterial pathogen, and Illumina high-throughput sequencing was used for profiling ARGs. The results showed that the WWTP had good removal efficiency on potential pathogenic bacteria (especially Arcobacter butzleri) and ARGs. Moreover, the bacterial communities of downstream and upstream of the river showed no significant difference. However, the increase in the abundance of potential pathogens and ARGs at effluent outfall was observed, indicating that WWTP effluent might contribute to the dissemination of potential pathogenic bacteria and ARGs in the receiving river.

  17. Combining ability of Phaseolus vulgaris L. for resistance to common bacterial blight

    Directory of Open Access Journals (Sweden)

    Rosana Rodrigues

    1999-12-01

    Full Text Available Many diseases limit dry bean and snap bean yields. Common bacterial blight (CBB, caused by Xanthomonas axonopodis pv. phaseoli, is one of the most serious bacterial diseases in dry bean and snap bean that cause crop losses. Since there is no satisfactory chemical control, the use of resistant cultivars is an important control measure. Genetic studies of resistance are important for choosing appropriate breeding methods. Combining ability was determined for disease resistance in three snap bean genotypes (Alessa, Hab 52 and Hab 198 and two dry bean genotypes (Bac-6 and A-794. Plants were inoculated with highly pathogenic isolate CNF 15, using a razor blade procedure in leaves and needle punctures in pods. They were evaluated 7 days after inoculation. Leaves were evaluated on a 1 to 5 scale and pods by lesion diameter. Diallel analysis was conducted using Griffing's model. General combining ability (GCA was significant for both leaf and pod infection, whereas specific combining ability (SCA was significant for disease reaction in pods. Bac-6 and A-794 were considered superior genotypes for leaf resistance. Nonadditive effects were predominant in pod reactions, and Alessa x Bac-6, Alessa x A-794 and Hab 52 x Bac-6 were the best combinations.Entre as várias doenças que causam problemas às culturas do feijão-de-vagem e do feijão comum, uma das mais importantes é o crestamento bacteriano comum (CBB, causado pela bactéria Xanthomonas axonopodis pv. phaseoli, que pode ocasionar grandes perdas na produção. O controle químico não é eficiente, e entre as medidas de controle recomendadas, destaca-se a resistência genética. Estudos genéticos da resistência são básicos para a definição dos métodos de melhoramento a serem adotados para cada caso. Avaliou-se a capacidade de combinação de três genótipos de feijão-de-vagem (Alessa, Hab 52, Hab 198 e dois de feijão comum (Bac-6 e A-794 quanto à resistência ao CBB, em folhas e vagens. A

  18. Bacterial etiology of bloodstream infections and antimicrobial resistance in Dhaka, Bangladesh, 2005–2014

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    Dilruba Ahmed

    2017-01-01

    Full Text Available Abstract Background Bloodstream infections due to bacterial pathogens are a major cause of morbidity and mortality in Bangladesh and other developing countries. In these countries, most patients are treated empirically based on their clinical symptoms. Therefore, up to date etiological data for major pathogens causing bloodstream infections may play a positive role in better healthcare management. The aim of this study was to identify the bacterial pathogens causing major bloodstream infections in Dhaka, Bangladesh and determine their antibiotic susceptibility pattern. Methods From January 2005 to December 2014, a total of 103,679 single bottle blood samples were collected from both hospitalized and domiciliary patients attending Dhaka hospital, icddrb, Bangladesh All the blood samples were processed for culture using a BACT/Alert blood culture machine. Further identification of bacterial pathogens and their antimicrobial susceptibility test were performed using standard microbiological procedures. Results Overall, 13.6% of the cultured blood samples were positive and Gram-negative (72.1% bacteria were predominant throughout the study period. Salmonella Typhi was the most frequently isolated organism (36.9% of samples in this study and a high percentage of those strains were multidrug-resistant (MDR. However, a decreasing trend in the S. Typhi isolation rate was observed and, noticeably, the percentage of MDR S. Typhi isolated declined sharply over the study period. An overall increase in the presence of Gram-positive bacteria was observed, but most significantly we observed the percentage of MDR Gram-positive bacteria to double over the study period. Overall, Gram positive bacteria were more resistant to most of the commonly used antibiotics than Gram-negative bacteria, but the MDR level was high in both groups. Conclusions This study identified the major bacterial pathogens involved with BSI in Dhaka, Bangladesh and also revealed their

  19. Influence of silver additions to type 316 stainless steels on bacterial inhibition, mechanical properties, and corrosion resistance

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tseng, I-Sheng; Møller, Per;

    2010-01-01

    techniques. The microstructure of these 316 stainless steels was examined, and the influences of silver additions to 316 stainless steels on bacterial inhibition, mechanical properties, and corrosion resistance were investigated. This study suggested that silver-bearing 316 stainless steels could be used......Bacterial contamination is a major concern in many areas. In this study, silver was added to type 316 stainless steels in order to obtain an expected bacteria inhibiting property to reduce the occurrence of bacterial contamination. Silver-bearing 316 stainless steels were prepared by vacuum melting...

  20. Does the appearance of drug resistance during therapy alter bacterial susceptibility to opsonophagocytosis?

    Science.gov (United States)

    Gemmell, C G

    1996-01-01

    Coagulase-negative staphylococci (CNS) are common causes of infection in patients undergoing chronic ambulatory peritoneal dialysis (CAPD). Their ability to survive intracellularly within peritoneal macrophages and to persist within the peritoneum during antibiotic therapy has led to the development of drug resistance during treatment. Strains of Staphylococcus epidermidis (SE) and Staphytococcus haemolyticus (SH) have been isolated from patients with CAPD during treatment with ciprofloxacin. The respective MIC values pre-and post-therapy were SE-0.25 and 128 mg/L and SH-0.50 and 64 mg/L. The susceptibility of each isolate to opsonophagocytosis was measured in vitro using isolated polymorphonuclear leucocytes (PMN) derived from fresh human blood donations. The bacteria were radiolabelled during growth, opsonised in either 1 or 10% serum and their uptake measured No differences were seen between the pre- and post therapy isolates when using 10% serum as opsonic source (18 vs. 21%); with 1% serum the corresponding values were lower (5 and 8% respectively). Similarly their ability to generate a respiratory burst as measured by chemiluminescence (CL) in the phagocytic cells was not diminished in the strains which had developed resistance to ciprofloxacin. The mean CL response to the strains isolated at outset of therapy ranged from 0.35-0.45 cpsc, and to the resistant strains following therapy from 0.36-0.50 cpsc. It is clear from the present investigation that although the bacterial strain became at least 10 times more resistant to ciprofloxacin during therapy, no change in their susceptibility to phagocytosis occurred refuting the idea that the emergence of drug resistant strains during therapy results in "super-bugs" of greater virulence.

  1. Application of Targeted Molecular and Material Property Optimization to Bacterial Attachment-Resistant (Meth)acrylate Polymers.

    Science.gov (United States)

    Adlington, Kevin; Nguyen, Nam T; Eaves, Elizabeth; Yang, Jing; Chang, Chien-Yi; Li, Jianing; Gower, Alexandra L; Stimpson, Amy; Anderson, Daniel G; Langer, Robert; Davies, Martyn C; Hook, Andrew L; Williams, Paul; Alexander, Morgan R; Irvine, Derek J

    2016-09-12

    Developing medical devices that resist bacterial attachment and subsequent biofilm formation is highly desirable. In this paper, we report the optimization of the molecular structure and thus material properties of a range of (meth)acrylate copolymers which contain monomers reported to deliver bacterial resistance to surfaces. This optimization allows such monomers to be employed within novel coatings to reduce bacterial attachment to silicone urinary catheters. We show that the flexibility of copolymers can be tuned to match that of the silicone catheter substrate, by copolymerizing these polymers with a lower Tg monomer such that it passes the flexing fatigue tests as coatings upon catheters, that the homopolymers failed. Furthermore, the Tg values of the copolymers are shown to be readily estimated by the Fox equation. The bacterial resistance performance of these copolymers were typically found to be better than the neat silicone or a commercial silver containing hydrogel surface, when the monomer feed contained only 25 v% of the "hit" monomer. The method of initiation (either photo or thermal) was shown not to affect the bacterial resistance of the copolymers. Optimized synthesis conditions to ensure that the correct copolymer composition and to prevent the onset of gelation are detailed.

  2. Identification of molecular markers linked to rice bacterial blight resistance genes from Oryza meyeriana

    Directory of Open Access Journals (Sweden)

    Jing WANG,Chen CHENG,Yanru ZHOU,Yong YANG,Qiong MEI,Junmin LI,Ye CHENG,Chengqi YAN,Jianping CHEN

    2015-09-01

    Full Text Available Y73 is a progeny of asymmetric somatic hybridization between Oryza sativa cv. Dalixiang and the wild rice species Oryza meyeriana. Inoculation with a range of strains of Xanthomonas oryzae pv. oryzae showed that Y73 had inherited a high level of resistance to rice bacterial blight (BB from its wild parent. An F2 population of 7125 individuals was constructed from the cross between Y73 and a BB-susceptible cultivar IR24. After testing 615 SSR and STS markers covering the 12 rice chromosomes, 186 markers were selected that showed polymorphism between Y73 and IR24. Molecular markers linked to the BB resistance genes in Y73 were scanned using the F2 population and the polymorphic markers. The SSR marker RM128 on chromosome 1, the STS marker R03D159 on chromosome 3 and the STS marker R05D104 on chromosome 5 were found to be linked to the rice BB resistance genes in Y73.

  3. Conformational landscape and pathway of disulfide bond reduction of human alpha defensin

    NARCIS (Netherlands)

    Snijder, Joost; Van De Waterbeemd, Michiel; Glover, Matthew S.; Shi, Liuqing; Clemmer, David E.; Heck, Albert J R

    2015-01-01

    Human alpha defensins are a class of antimicrobial peptides with additional antiviral activity. Such antimicrobial peptides constitute a major part of mammalian innate immunity. Alpha defensins contain six cysteines, which form three well defined disulfide bridges under oxidizing conditions. Residue

  4. In vitro inhibitory potentials of crude plant extracts on multidrug resistant bacterial species from infected human wounds

    Directory of Open Access Journals (Sweden)

    Yetunde A Ekanola

    2013-01-01

    Full Text Available Background: Scientific data on usage of plants to promote wound healing is exclusively scare in Nigeria. AIM: The aim of this study was to determine in vitro inhibitory potentials of crude extracts of garlic (Allium sativum and ginger (Zingiber officinale on multiple antibiotic resistant bacteria isolated from deep and superficial human wounds. Materials and Methods: Using agar disc- and modified agar well-diffusion methods, 87 wound-borne bacterial strains, Staphylococcus aureus, Proteus mirabilis and Pseudomonas aeruginosa were screened for in vitro susceptibility to 15 commonly-available antibiotic discs, 18 antibiotic drugs and three plant extracts. Results: Staph. aureus strains exhibited 52.5-97.4% resistance to antibiotic (discs, with multiple antibiotic resistance (MAR of 25.0 -100%. Between 39.1 and 95.7% of Proteus mirabilis strains resisted the antibiotics (discs, while MAR was 37.5-100%. Resistance rates displayed by Ps. aeruginosa strains were 61.5-100% with MAR of 50.0-100%. Overall antibiotic resistance patterns of respective bacterial species recorded for the antibiotic drugs were Staph. aureus (11.1-83.3%, Pr. mirabilis (16.7-77.8% and Ps. aeruginosa (16.7-50.0% and the most-resisted antibiotic drugs were axacef (55.3-82.6%, septrin (84.2-92.3%, primpex (78.3-84.6%, mediphenicol (63.2-73.1% and augmentin 1 (43.2-76.9%. All the multidrug resistant wound-borne bacterial strains exhibited minimal to moderate susceptibility towards crude extracts of garlic (17.4-34.6% and ginger (57.7-60.8%. Conclusion: Human wound-borne bacterial strains, which were multi-resistant to commonly available antibiotics (discs/drugs were minimally or moderately susceptible to crude extracts of garlic (Allium sativum and ginger (Zingiber officinale, which can be of clinical importance as herbal therapy in wound dressings or other forms of wound treatments.

  5. Bacterial Etiology and Antibiotic Resistance Profile of Community-Acquired Urinary Tract Infections in a Cameroonian City

    Science.gov (United States)

    Gonsu, Hortense Kamga; Koulla-Shiro, Sinata

    2016-01-01

    Introduction. Community-acquired urinary tract infections (CAUTIs) are usually treated empirically. Geographical variations in etiologic agents and their antibiotic sensitivity patterns are common. Knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Our aim was to determine the major bacterial etiologies of CAUTIs and their antibiotic resistance patterns in a cosmopolitan area of Cameroon for comparison with prescription practices of local physicians. Methods. We performed a cross-sectional descriptive study at two main hospitals in Yaoundé, collecting a clean-catch mid-stream urine sample from 92 patients having a clinical diagnosis of UTI. The empirical antibiotherapy was noted, and identification of bacterial species was done on CLED agar; antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Results. A total of 55 patients had samples positive for a UTI. Ciprofloxacin and amoxicillin/clavulanic acid were the most empirically prescribed antibiotics (30.9% and 23.6%, resp.); bacterial isolates showed high prevalence of resistance to both compounds. Escherichia coli (50.9%) was the most common pathogen, followed by Klebsiella pneumoniae (16.4%). Prevalence of resistance for ciprofloxacin was higher compared to newer quinolones. Conclusions. E. coli and K. pneumoniae were the predominant bacterial etiologies; the prevalence of resistance to commonly prescribed antibiotics was high. PMID:27667998

  6. The role played by drug efflux pumps in bacterial multidrug resistance.

    Science.gov (United States)

    Chitsaz, Mohsen; Brown, Melissa H

    2017-02-28

    Antimicrobial resistance is a current major challenge in chemotherapy and infection control. The ability of bacterial and eukaryotic cells to recognize and pump toxic compounds from within the cell to the environment before they reach their targets is one of the important mechanisms contributing to this phenomenon. Drug efflux pumps are membrane transport proteins that require energy to export substrates and can be selective for a specific drug or poly-specific that can export multiple structurally diverse drug compounds. These proteins can be classified into seven groups based on protein sequence homology, energy source and overall structure. Extensive studies on efflux proteins have resulted in a wealth of knowledge that has made possible in-depth understanding of the structures and mechanisms of action, substrate profiles, regulation and possible inhibition of many clinically important efflux pumps. This review focuses on describing known families of drug efflux pumps using examples that are well characterized structurally and/or biochemically.

  7. Microarray Analysis of the Transcriptome for Bacterial Wilt Resistance in Pepper (Capsicum annuum L.

    Directory of Open Access Journals (Sweden)

    Jihyun HWANG

    2011-11-01

    Full Text Available Ralstonia solanacearum causes one of the most common soil-borne vascular diseases of diverse plant species, including many solanaceous crops such as tomato and pepper. The resulting disease, bacterial wilt (BW, is devastating and difficult to control using conventional approaches. The aim of this study was to investigate the differentially expressed genes in pepper root systems in response to infection by R. solanacearum. DNA microarray (Capsicum annuum 135K Microarray v3.0 Gene Expression platform analyses were performed using a susceptible genotype, ‘Chilbok’, and a resistant genotype, ‘KC350’, at 3 time points (1, 3, and 6 days post inoculation. It has been identified 115 resistance-specific genes (R-response genes and 109 susceptibility-specific genes (S-response gene, which were up-regulated in 1 genotype, but down-regulated in the other genotype. Gene Ontology (GO analysis for functional categorization indicated that many R-response genes were related to genes that function in xyloglucan biosynthesis and cell wall organization, while S-response genes were involved in the response to stress and cell death. The expression of genes encoding xyloglucan endotransglycosylase/hydrolase (XTH and β-galactosidase were verified by real-time RT-PCR at an early time point of R. solanacearum infection. The results supported the idea that rapidly induced XTH expression in ‘KC350’ may play an important role in the restructuring and reinforcement of the cell wall and restrict bacterial movement in xylem vessels. In addition, induced expression of β-galactosidase in R. solanacearum-infected ‘Chilbok’ implied that degradation of the cell wall structure in vascular tissues by β-galactosidase might be an important factor facilitating R. solanacearum invasion of and movement in susceptible host plants.

  8. Bacteriophage therapy for membrane biofouling in membrane bioreactors and antibiotic-resistant bacterial biofilms.

    Science.gov (United States)

    Bhattacharjee, Ananda Shankar; Choi, Jeongdong; Motlagh, Amir Mohaghegh; Mukherji, Sachiyo T; Goel, Ramesh

    2015-08-01

    To demonstrate elimination of bacterial biofilm on membranes to represent wastewater treatment as well as biofilm formed by antibiotic-resistant bacterial (ARB) to signify medical application, an antibiotic-resistant bacterium and its lytic bacteriophage were isolated from a full-scale wastewater treatment plant. Based on gram staining and complete 16 S rDNA sequencing, the isolated bacterium showed a more than 99% homology with Delftia tsuruhatensis, a gram-negative bacterium belonging to β-proteobacteria. The Delftia lytic phage's draft genome revealed the phage to be an N4-like phage with 59.7% G + C content. No transfer RNAs were detected for the phage suggesting that the phage is highly adapted to its host Delftia tsuruhatensis ARB-1 with regard to codon usage, and does not require additional tRNAs of its own. The gene annotation of the Delftia lytic phage found three different components of RNA polymerase (RNAP) in the genome, which is a typical characteristic of N4-like phages. The lytic phage specific to D. tsuruhatensis ARB-1 could successfully remove the biofilm formed by it on a glass slide. The water flux through the membrane of a prototype lab-scale membrane bioreactor decreased from 47 L/h m(2) to ∼15 L/h m(2) over 4 days due to a biofilm formed by D. tsuruhatensis ARB-1. However, the flux increased to 70% of the original after the lytic phage application. Overall, this research demonstrated phage therapy's great potential to solve the problem of membrane biofouling, as well as the problems posed by pathogenic biofilms in external wounds and on medical instruments.

  9. Field evaluation of the bacterial volatile derivative 3-pentanol in priming for induced resistance in pepper.

    Science.gov (United States)

    Choi, Hye Kyung; Song, Geun Cheol; Yi, Hwe-Su; Ryu, Choong-Min

    2014-08-01

    Plants are defended from attack by emission of volatile organic compounds (VOCs) that can act directly against pathogens and herbivores or indirectly by recruiting natural enemies of herbivores. However, microbial VOC have been less investigated as potential triggers of plant systemic defense responses against pathogens in the field. Bacillus amyloliquefaciens strain IN937a, a plant growth-promoting rhizobacterium that colonizes plant tissues, stimulates induced systemic resistance (ISR) via its emission of VOCs. We investigated the ISR capacity of VOCs and derivatives collected from strain IN937a against bacterial spot disease caused by Xanthomonas axonopodis pv. vesicatoria in pepper. Of 15 bacterial VOCs and their derivatives, 3-pentanol, which is a C8 amyl alcohol reported to be a component of sex pheromones in insects, was selected for further investigation. Pathogens were infiltrated into pepper leaves 10, 20, 30, and 40 days after treatment and transplantation to the field. Disease severity was assessed 7 days after transplantation. Treatment with 3-pentanol significantly reduced disease severity caused by X. axonopodis and naturally occurring Cucumber mosaic virus in field trials over 2 years. We used quantitative real-time polymerase chain analysis to examine Pathogenesis-Related genes associated with salicylic acid (SA), jasmonic acid (JA), and ethylene defense signaling. The expression of Capsicum annuum Pathogenesis-Related protein 1 (CaPR1), CaPR2, and Ca protease inhibitor2 (CaPIN2) increased in field-grown pepper plants treated with 3-pentanol. Taken together, our results show that 3-pentanol triggers induced resistance by priming SA and JA signaling in pepper under field conditions.

  10. Housefly Larva Vermicomposting Efficiently Attenuates Antibiotic Resistance Genes in Swine Manure, with Concomitant Bacterial Population Changes.

    Science.gov (United States)

    Wang, Hang; Li, Hongyi; Gilbert, Jack A; Li, Haibo; Wu, Longhua; Liu, Meng; Wang, Liling; Zhou, Qiansheng; Yuan, Junxiang; Zhang, Zhijian

    2015-11-01

    Manure from swine treated with antimicrobials as feed additives is a major source for the expansion of the antibiotic resistance gene (ARG) reservoir in the environment. Vermicomposting via housefly larvae (Musca domestica) can be efficiently used to treat manure and regenerate biofertilizer, but few studies have investigated its effect on ARG attenuation. Here, we tracked the abundances of 9 ARGs and the composition and structure of the bacterial communities in manure samples across 6 days of full-scale manure vermicomposting. On day 6, the abundances of genes encoding tetracycline resistance [tet(M), tet(O), tet(Q), and tet(W)] were reduced (P < 0.05), while those of genes encoding sulfonamide resistance (sul1 and sul2) were increased (P < 0.05) when normalized to 16S rRNA. The abundances of tetracycline resistance genes were correlated (P < 0.05) with the changing concentrations of tetracyclines in the manure. The overall diversity and richness of the bacteria significantly decreased during vermicomposting, accompanied by a 100 times increase in the relative abundance of Flavobacteriaceae spp. Variations in the abundances of ARGs were correlated with the changing microbial community structure and the relative abundances of the family Ruminococcaceae, class Bacilli, or phylum Proteobacteria. Vermicomposting, as a waste management practice, can reduce the overall abundance of ARGs. More research is warranted to assess the use of this waste management practice as a measure to attenuate the dissemination of antimicrobial residues and ARGs from livestock production before vermicompost can be safely used as biofertilizer in agroecosystems.

  11. Modeling of the bacterial mechanism of methicillin-resistance by a systems biology approach.

    Directory of Open Access Journals (Sweden)

    Ida Autiero

    Full Text Available BACKGROUND: A microorganism is a complex biological system able to preserve its functional features against external perturbations and the ability of the living systems to oppose to these external perturbations is defined "robustness". The antibiotic resistance, developed by different bacteria strains, is a clear example of robustness and of ability of the bacterial system to acquire a particular functional behaviour in response to environmental changes. In this work we have modeled the whole mechanism essential to the methicillin-resistance through a systems biology approach. The methicillin is a beta-lactamic antibiotic that act by inhibiting the penicillin-binding proteins (PBPs. These PBPs are involved in the synthesis of peptidoglycans, essential mesh-like polymers that surround cellular enzymes and are crucial for the bacterium survival. METHODOLOGY: The network of genes, mRNA, proteins and metabolites was created using CellDesigner program and the data of molecular interactions are stored in Systems Biology Markup Language (SBML. To simulate the dynamic behaviour of this biochemical network, the kinetic equations were associated with each reaction. CONCLUSIONS: Our model simulates the mechanism of the inactivation of the PBP by methicillin, as well as the expression of PBP2a isoform, the regulation of the SCCmec elements (SCC: staphylococcal cassette chromosome and the synthesis of peptidoglycan by PBP2a. The obtained results by our integrated approach show that the model describes correctly the whole phenomenon of the methicillin resistance and is able to respond to the external perturbations in the same way of the real cell. Therefore, this model can be useful to develop new therapeutic approaches for the methicillin control and to understand the general mechanism regarding the cellular resistance to some antibiotics.

  12. Antiplasmodial activity is an ancient and conserved feature of tick defensins

    Directory of Open Access Journals (Sweden)

    Alejandro Cabezas-Cruz

    2016-10-01

    Full Text Available Ancestral sequence reconstruction has been widely used to test evolution-based hypotheses. The genome of the European tick vector, Ixodes ricinus, encodes for defensin peptides with diverse antimicrobial activities against distantly related pathogens. These pathogens include fungi, Gram-negative and Gram-positive bacteria, i.e., a wide antimicrobial spectrum. Ticks do not transmit these pathogens, suggesting that these defensins may act against a wide range of microbes encountered by ticks during blood feeding or off-host periods. As demonstrated here, these I. ricinus defensins are also effective against the apicomplexan parasite Plasmodium falciparum. To study the general evolution of antimicrobial activity in tick defensins, the ancestral amino acid sequence of chelicerate defensins, which existed approximately 444 million years ago, was reconstructed using publicly available scorpion and tick defensin sequences (named Scorpions-Ticks Defensins Ancestor, STiDA. The activity of STiDA was tested against P. falciparum and the same Gram-negative and Gram-positive bacteria that were used for the I. ricinus defensins. While some extant tick defensins exhibit a wide antimicrobial spectrum, the ancestral defensin showed moderate activity against one of the tested microbes, P. falciparum. This study suggests that amino acid variability and defensin family expansion increased the antimicrobial spectrum of ancestral tick defensins.

  13. Plasma alpha-defensin is associated with cardiovascular morbidity and mortality in type 1 diabetic patients

    DEFF Research Database (Denmark)

    Joseph, G.; Tarnow, L.; Astrup, A.S.;

    2008-01-01

    CONTEXT: alpha-Defensins are antimicrobial peptides of the innate immune system. In addition, experimental evidence suggests that alpha-defensins are proatherogenic. OBJECTIVE: The objective of the study was to examine the predictive value of plasma alpha-defensin as a clinical marker...

  14. Bacterial Etiology and Antibiotic Resistance Profile of Community-Acquired Urinary Tract Infections in a Cameroonian City

    OpenAIRE

    Rolf Nyah-tuku Nzalie; Hortense Kamga Gonsu; Sinata Koulla-Shiro

    2016-01-01

    Introduction. Community-acquired urinary tract infections (CAUTIs) are usually treated empirically. Geographical variations in etiologic agents and their antibiotic sensitivity patterns are common. Knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Our aim was to determine the major bacterial etiologies of CAUTIs and their antibiotic resistance patterns in a cosmopolitan area of Cameroon for comparison with pres...

  15. The evolution of bacterial resistance against bacteriophages in the horse chestnut phyllosphere is general across both space and time.

    Science.gov (United States)

    Koskella, Britt; Parr, Nicole

    2015-08-19

    Insight to the spatial and temporal scales of coevolution is key to predicting the outcome of host-parasite interactions and spread of disease. For bacteria infecting long-lived hosts, selection to overcome host defences is just one factor shaping the course of evolution; populations will also be competing with other microbial species and will themselves be facing infection by bacteriophage viruses. Here, we examine the temporal and spatial patterns of bacterial adaptation against natural phage populations from within leaves of horse chestnut trees. Using a time-shift experiment with both sympatric and allopatric phages from either contemporary or earlier points in the season, we demonstrate that bacterial resistance is higher against phages from the past, regardless of spatial sympatry or how much earlier in the season phages were collected. Similarly, we show that future bacterial hosts are more resistant to both sympatric and allopatric phages than contemporary bacterial hosts. Together, our results suggest the evolution of relatively general bacterial resistance against phages in nature and are contrasting to previously observed patterns of phage adaptation to bacteria from the same tree hosts over the same time frame, indicating a potential asymmetry in coevolutionary dynamics.

  16. Assessment of anaerobic bacterial diversity and its effects on anaerobic system stability and the occurrence of antibiotic resistance genes.

    Science.gov (United States)

    Aydin, Sevcan; Ince, Bahar; Ince, Orhan

    2016-05-01

    This study evaluated the link between anaerobic bacterial diversity and, the biodegradation of antibiotic combinations and assessed how amending antibiotic combination and increasing concentration of antibiotics in a stepwise fashion influences the development of resistance genes in anaerobic reactors. The biodegradation, sorption and occurrence of the known antibiotic resistance genes (ARGs) of erythromycin and tetracycline were investigated using the processes of UV-HPLC and qPCR analysis respectively. Ion Torrent sequencing was used to detect microbial community changes in response to the addition of antibiotics. The overall results indicated that changes in the structure of a microbial community lead to changes in biodegradation capacity, sorption of antibiotics combinations and occurrence of ARGs. The enhanced biodegradation efficiency appeared to generate variations in the structure of the bacterial community. The results suggested that controlling the ultimate Gram-negative bacterial community, especially Acinetobacter-related populations, may promote the successful biodegradation of antibiotic combinations and reduce the occurrence of ARGs.

  17. EXPRESSION OF BACTERIAL PROTEIN-A IN TOBACCO LEADS TO ENHANCED RESISTANCE TO STRESS CONDITIONS

    Directory of Open Access Journals (Sweden)

    Chaitali Roy

    2014-08-01

    Full Text Available Tobacco is the most commonly used plant for expression of transgenes from a variety of organisms because it can be easily grown and transformed, it provides abundant amounts of fresh tissue and has a well-established cell culture system. As bacterial enzymes can be synthesized in tobacco, here we explore the possibility of in planta expression of staphylococcal protein-A(PA which is an antibody, an important group among biopharmaceuticals. In our study we have shown that the tobacco plants harboring PA gene could combat the crown gall infection and also effective in resisting abiotic stress conditions. Transgenic plants when subjected to interact with wild variety of Agrobacterium shows its enhanced capability to resist the gall formation. And when transgenic tobacco plants were grown in presence of 200mM NaCl and/or MG(Methylglyoxal solution, shows their increased tolerance towards salinity stress and high MG stress. So far transgenic tobacco plants are concerned, improvements in the expression of recombinant proteins and their recovery from tobacco may also enhance production and commercial use of this protein.

  18. Resistance and resilience responses of a range of soil eukaryote and bacterial taxa to fungicide application.

    Science.gov (United States)

    Howell, Christopher C; Hilton, Sally; Semple, Kirk T; Bending, Gary D

    2014-10-01

    The application of plant protection products has the potential to significantly affect soil microbial community structure and function. However, the extent to which soil microbial communities from different trophic levels exhibit resistance and resilience to such compounds remains poorly understood. The resistance and resilience responses of a range of microbial communities (bacteria, fungi, archaea, pseudomonads, and nematodes) to different concentrations of the strobilurin fungicide, azoxystrobin were studied. A significant concentration-dependent decrease, and subsequent recovery in soil dehydrogenase activity was recorded, but no significant impact on total microbial biomass was observed. Impacts on specific microbial communities were studied using small subunit (SSU) rRNA terminal restriction fragment length polymorphism (T-RFLP) profiling using soil DNA and RNA. The application of azoxystrobin significantly affected fungal and nematode community structure and diversity but had no impact on other communities. Community impacts were more pronounced in the RNA-derived T-RFLP profiles than in the DNA-derived profiles. qPCR confirmed that azoxystrobin application significantly reduced fungal, but not bacterial, SSU rRNA gene copy number. Azoxystrobin application reduced the prevalence of ascomycete fungi, but increased the relative abundance of zygomycetes. Azoxystrobin amendment also reduced the relative abundance of nematodes in the order Enoplia, but stimulated a large increase in the relative abundance of nematodes from the order Araeolaimida.

  19. Bacterial Contamination and Antibiotic Resistance of Staphylococcus Aureus Isolated from Automated Teller Machine

    Directory of Open Access Journals (Sweden)

    Moshtaghi, H. (PhD

    2015-05-01

    Full Text Available Background and Objective: Automated Teller Machine (ATMs is likely to be contaminated with various microorganisms specially pathogen germs. This may be due to their exposure to dust and their vast dermal contact with multiple users. This study investigated the bacterial contamination on the keyboard of ATMs and drug resistance of the bacteria isolated from them. Material and Methods: the keyboards of 50 ATMs in Shahrekord city, Iran, were examined from October 2012 to February 2013. The sterile swab sticks moistened with Triptose soy broth were used for sampling. The bacteriological tests used were culture, biochemical test and agar disk diffusion method for antibiogram. Results: All the samples were found to be contaminated with Coagulase negative staphylococci (57.54%, Bacillus species (21.92%, Staphylococcus aureus (19.18% and coliform bacteria (1.36%. The resistance of Staphylococcus aureus was 92.8% to penicillin, 85.7% to amoxicilin، 71.4% to ampicillin, 57.1% to nytrofuran, 50% to tetracycline, 42.8% to erythromycin, 42.8% to gentamycin, 14.2 % to ciprofloxacin, 7.1% to trimethoprim and sulfamtuksazul. All species were susceptible to, ofloxacine, chloramphenicol, clindamycin, tobramycin, vancomycin and cefotaxime. Conclusion: given the presence of pathogens on ATMs and their role in transferring the contamination, we recommend considering personal hygiene and periodically disinfecting the keyboards to reduce contamination

  20. Bioremediation potential of a highly mercury resistant bacterial strain Sphingobium SA2 isolated from contaminated soil.

    Science.gov (United States)

    Mahbub, Khandaker Rayhan; Krishnan, Kannan; Megharaj, Mallavarapu; Naidu, Ravi

    2016-02-01

    A mercury resistant bacterial strain, SA2, was isolated from soil contaminated with mercury. The 16S rRNA gene sequence of this isolate showed 99% sequence similarity to the genera Sphingobium and Sphingomonas of α-proteobacteria group. However, the isolate formed a distinct phyletic line with the genus Sphingobium suggesting the strain belongs to Sphingobium sp. Toxicity studies indicated resistance to high levels of mercury with estimated EC50 values 4.5 mg L(-1) and 44.15 mg L(-1) and MIC values 5.1 mg L(-1) and 48.48 mg L(-1) in minimal and rich media, respectively. The strain SA2 was able to volatilize mercury by producing mercuric reductase enzyme which makes it potential candidate for remediating mercury. ICP-QQQ-MS analysis of Hg supplemented culture solutions confirmed that almost 79% mercury in the culture suspension was volatilized in 6 h. A very small amount of mercury was observed to accumulate in cell pellets which was also evident according to ESEM-EDX analysis. The mercuric reductase gene merA was amplified and sequenced. The deduced amino acid sequence demonstrated sequence homology with α-proteobacteria and Ascomycota group.

  1. Nucleotide diversity analysis of three major bacterial blight resistance genes in rice.

    Directory of Open Access Journals (Sweden)

    Waikhom Bimolata

    Full Text Available Nucleotide sequence polymorphisms among R gene alleles influence the process of co-evolutionary interaction between host and pathogen by shaping the response of host plants towards invading pathogens. Here, we present the DNA sequence polymorphisms and diversities present among natural alleles of three rice bacterial blight resistance genes, Xa21, Xa26 and xa5. The diversity was examined across different wild relatives and cultivars of Oryza species. Functional significance of selected alleles was evaluated through semi-quantitative reverse transcription polymerase chain reaction and real time PCR. The greatest nucleotide diversity and singleton variable sites (SVS were present in Xa26 (π = 0.01958; SVS = 182 followed by xa5 and Xa21 alleles. The highest frequency of single nucleotide polymorphisms were observed in Xa21 alleles and least in xa5. Transition bias was observed in all the genes and 'G' to 'A' transitions were more favored than other form of transitions. Neutrality tests failed to show the presence of selection at these loci, though negative Tajima's D values indicate the presence of a rare form of polymorphisms. At the interspecies level, O. nivara exhibited more diversity than O. sativa. We have also identified two nearly identical resistant alleles of xa5 and two sequentially identical alleles of Xa21. The alleles of xa5 showed basal levels of expression while Xa21 alleles were functionally not expressed.

  2. Housefly Larva Vermicomposting Efficiently Attenuates Antibiotic Resistance Genes in Swine Manure, with Concomitant Bacterial Population Changes

    Science.gov (United States)

    Wang, Hang; Li, Hongyi; Gilbert, Jack A.; Li, Haibo; Wu, Longhua; Liu, Meng; Wang, Liling; Zhou, Qiansheng; Yuan, Junxiang

    2015-01-01

    Manure from swine treated with antimicrobials as feed additives is a major source for the expansion of the antibiotic resistance gene (ARG) reservoir in the environment. Vermicomposting via housefly larvae (Musca domestica) can be efficiently used to treat manure and regenerate biofertilizer, but few studies have investigated its effect on ARG attenuation. Here, we tracked the abundances of 9 ARGs and the composition and structure of the bacterial communities in manure samples across 6 days of full-scale manure vermicomposting. On day 6, the abundances of genes encoding tetracycline resistance [tet(M), tet(O), tet(Q), and tet(W)] were reduced (P vermicomposting, accompanied by a 100 times increase in the relative abundance of Flavobacteriaceae spp. Variations in the abundances of ARGs were correlated with the changing microbial community structure and the relative abundances of the family Ruminococcaceae, class Bacilli, or phylum Proteobacteria. Vermicomposting, as a waste management practice, can reduce the overall abundance of ARGs. More research is warranted to assess the use of this waste management practice as a measure to attenuate the dissemination of antimicrobial residues and ARGs from livestock production before vermicompost can be safely used as biofertilizer in agroecosystems. PMID:26296728

  3. [Investigation of microbicidal activity of neutrophil defensins against leptospires].

    Science.gov (United States)

    Wu, Q; Xu, L; Wang, X; Li, S; Wang, B

    1992-06-01

    Defensins play an important role in oxygen-independent microbicidal mechanisms of neutrophils. They are effective against many bacteria, fungi and enveloped viruses. However, the effect of defensins upon leptospires has not been studied. In the present report, human defensins (i.e. HNP, a mixture of HNP1, HNP2 and HNP3 were prepared from human polymorphonuclear neutrophils by chromatography on Sephadex G-100 and then on Biogel P-10. Rabbit defensin NP1 was purified from rabbit peritoneal granulocytes by preparative acid urea polyacrylamide gel electrophoresis. By using the most-probable-number procedure, HNP and NP1 were tested in vitro for the killing of leptospira interrogans serogroup icteroheamorrhagiae serovar lai strain 017. NP1 was highly effective. When leptospires of strain 017 were incubated with 1 microgram/ml of NP1 at 30 degrees C for 4 hours, > 99% of these organisms were killed. HNP was less potent than NP1, and at 50 micrograms/ml, it killed > 90% of leptospires. As is also the case for the killing of bacteria, NP1 was active against leptospires in nutrient-free buffer, whereas HNP required the addition of glucose. The data suggest that defensins could play a major role in the killing of leptospires by neutrophils.

  4. Evaluation of triticale accessions for resistance to wheat bacterial leaf streak caused by Xanthomonas translucens pv. undulosa

    Science.gov (United States)

    The bacterium Xanthomonas translucens pv. undulosa (Xtu) causes bacterial leaf streak (BLS) on wheat and other small grains. Several triticale accessions were reported to possess high levels of resistance to wheat Xtu strains. In this study, we evaluated a worldwide collection of 502 triticale acces...

  5. Yeast cell wall extract induces disease resistance against bacterial and fungal pathogens in Arabidopsis thaliana and Brassica crop.

    Directory of Open Access Journals (Sweden)

    Mari Narusaka

    Full Text Available Housaku Monogatari (HM is a plant activator prepared from a yeast cell wall extract. We examined the efficacy of HM application and observed that HM treatment increased the resistance of Arabidopsis thaliana and Brassica rapa leaves to bacterial and fungal infections. HM reduced the severity of bacterial leaf spot and anthracnose on A. thaliana and Brassica crop leaves with protective effects. In addition, gene expression analysis of A. thaliana plants after treatment with HM indicated increased expression of several plant defense-related genes. HM treatment appears to induce early activation of jasmonate/ethylene and late activation of salicylic acid (SA pathways. Analysis using signaling mutants revealed that HM required SA accumulation and SA signaling to facilitate resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Colletotrichum higginsianum. In addition, HM-induced resistance conferred chitin-independent disease resistance to bacterial pathogens in A. thaliana. These results suggest that HM contains multiple microbe-associated molecular patterns that activate defense responses in plants. These findings suggest that the application of HM is a useful tool that may facilitate new disease control methods.

  6. Altering the thermal resistance of foodborne bacterial pathogens with an eggshell membrane waste by-product.

    Science.gov (United States)

    Poland, A L; Sheldon, B W

    2001-04-01

    Eggshells from egg-breaking operations are a significant waste disposal problem. Thus, the development of value-added by-products from this waste would be welcomed by the industry. The ability of extracted eggshell membranes containing, several bacteriolytic enzymes (i.e., lysozyme and beta-N-acetylglucosaminidase) or other membrane components to alter the thermal resistance of gram-positive and gram-negative bacterial pathogens was evaluated. Mid-log phase cells of Salmonella Enteritidis (SE), Salmonella Typhimurium (ST), Escherichia coli O157:H7 (EC), Listeria monocytogenes Scott A (LM), and Staphylococcus aureus (SA) were suspended in 100 ml of 0.1% peptone water (pH 6.9, 10(7-8) CFU/ml) containing either 0 (control) or 10 g of an eggshell membrane extract and incubated at 37 degrees C for 45 min. Following exposure, membrane-free samples (1.5 ml) were heated in a 56 degrees C (LM, SA), 54 degrees C (SE, ST), or 52 degrees C (EC) water bath from 0 to 14 min in sealed glass reaction vials (12 by 32 mm), and the survivors were recovered on brain heart infusion agar. Population reductions ranging from 27.6% (SA) to 99.8% (LM) (ST, 43.8%; SE, 47.5%; EC, 71.8%) were observed for cells treated for 45 min with extracted membrane, as compared to controls. D-value reductions ranging from 0 (LM) to 87.2% (SE) (SA, 36.7%; EC, 83.3%; ST, 86.3%) were observed when membrane-treated cells were subsequently heat inactivated. The effects of exposure pH, time, temperature, and organic load on membrane activity were also evaluated with Salmonella Typhimurium. Exposure pH (5.0 versus 6.9), time (15 versus 45 min), and temperature (4 degrees C versus 37 degrees C) did not significantly reduce the impact of eggshell membranes on D-values. However, the presence of organic matter (0.1% peptone water versus skim milk) significantly reduced the thermal resistance-reducing capacity of the membranes. These preliminary findings provide information on the potential use of extracted eggshell

  7. Human beta-defensin-2 increases cholinergic response in colon epithelium.

    Science.gov (United States)

    Himmerkus, Nina; Vassen, Veit; Sievers, Birte; Goerke, Boeren; Shan, Qixian; Harder, Jürgen; Schröder, Jens-Michael; Bleich, Markus

    2010-06-01

    The human beta-defensin-2 (hBD-2) is expressed in epithelial cells of skin and respiratory and gastrointestinal tracts. Defensins are arginine-rich small cationic peptides with six intramolecular disulfide bonds and are antimicrobially active against a broad spectrum of pathogens. In addition, they have cytokine-like immunomodulatory properties. We hypothesized that hBD-2 also might influence epithelial cells themselves, thereby altering fluid composition in the gastrointestinal tract. We therefore tested its impact on electrogenic ion transport properties of distal colon in Ussing chamber experiments. Application of hBD-2 did not affect transepithelial voltage or resistance in cAMP-stimulated distal colon. However, it increased cholinergic Ca(2+)-dependent Cl(-) secretion. After 20 min of incubation with hBD-2, the effect of carbachol (CCh) on the equivalent short circuit current (I'(sc)) was enhanced twofold compared to vehicle-treated colon. Modulation of Ca(2+) signaling by hBD-2 was validated by Fura-2 measurements in human colon carcinoma HT29 cells. Twenty-minute incubation with hBD-2 increased the CCh-induced Ca(2+) transient by 20-30% compared to either vehicle-treated cells or cells treated with the defensins hBD-1, hBD-3, or HD-5. This effect was concentration-dependent, with an EC(50) of 0.043 microg/ml, and still present in the absence of extracellular Ca(2+). Also, the ionomycin-induced Ca(2+) transient was increased by hBD-2 treatment. We conclude that hBD-2 facilitates cholinergic Ca(2+)-regulated epithelial Cl(-) secretion. These findings contribute to the concept of a specific interaction of antimicrobial peptides with epithelial function.

  8. [PK/PD Modeling as a Tool for Predicting Bacterial Resistance to Antibiotics: Alternative Analyses of Experimental Data].

    Science.gov (United States)

    Golikova, M V; Strukova, E N; Portnoy, Y A; Firsov, A A

    2015-01-01

    Postexposure number of mutants (NM) is a conventional endpoint in bacterial resistance studies using in vitro dynamic models that simulate antibiotic pharmacokinetics. To compare NM with a recently introduced integral parameter AUBC(M), the area under the time course of resistance mutants, the enrichment of resistant Staphylococcus aureus was studied in vitro by simulation of mono(daptomycin, doxycycline) and combined treatments (daptomycin + rifampicin, rifampicin + linezolid). Differences in the time courses of resistant S. aureus could be reflected by AUBC(M) but not N(M). Moreover, unlike AUBC(M), N(M) did not reflect the pronounced differences in the time courses of S. aureus mutants resistant to 2x, 4x, 8x and 16xMIC of doxycycline and rifampicin. The findings suggested that AUBC(M) was a more appropriate endpoint of the amplification of resistant mutants than N(M).

  9. Bacterial group behavior and drug resistance%细菌的群体性行为与耐药

    Institute of Scientific and Technical Information of China (English)

    王辉; 杨崇广; 牛辰

    2011-01-01

    With the increasing usage of antibiotics, bacterial drug resistance has become a serious problem.Bacterial drug resistance is a complex process, involving the host, bacteria and environment, which are independent and interactive factors.For a long time, scientists considered that bacteria behave as individual. Till recently, people found that bacteria communicate with each other. We begin to realize the importance of bacterial group behavior in survival. An increasing number of studies have tended to take bacteria as a group to study the behavior of drug resistance. Now, two important aspects of bacterial group behavior, the biofilm and bacterial programmed cell death draw a lot of attention. In this paper, the research associated with drug resistance mechanisms of biofilms and bacterial programmed cell death is reviewed.%随着抗生素的广泛使用,细菌耐药已经成为一个严重的问题.细菌耐药是一个复杂的过程,涉及宿主、细菌与环境等几个既相互独立又相互作用的因素.很久以来,人们认为细菌以个体为单位进行各种活动,直到发现细菌相互之间也存在联系,才意识到细菌群体对其个体生存的重要性.目前将细菌作为一个群体来研究其耐药行为与机制的研究越来越多,特别是细菌生物膜与细菌程序性死亡两方面受到极大重视.本文综述了细菌生物膜、细菌程序性死亡与耐药相关机制的研究进展.

  10. Frequency of bacterial isolates and pattern of antimicrobial resistance in patients with hematological malignancies: A snapshot from tertiary cancer center

    Directory of Open Access Journals (Sweden)

    M Sengar

    2015-01-01

    Full Text Available BACKGROUND: Infections are the most important cause of mortality in patients with high-risk febrile neutropenia. Emergence of multi-drug resistant organisms (MDROs has become a major challenge for hemato-oncologists. Knowledge of the prevalent organisms and their antimicrobial sensitivity can help deciding the empirical therapy at individual centers and allows timely measures to reduce the risk of antimicrobial resistance. AIMS: To evaluate the frequency of bacterial isolates from all the samples and the pattern of bacterial bloodstream infections and incidence of MDROs. SETTINGS AND DESIGN: This is a retrospective analysis from a tertiary care cancer center. MATERIALS AND METHODS: From January to June 2014 information on all the samples received in Department of Microbiology was collected retrospectively. The data from samples collected from patients with hematological cancers were analyzed for types of bacterial isolates and antimicrobial sensitivity. RESULTS: A total of 739 isolates were identified with 67.9% of isolates being Gram-negative. The predominant Gram-negative organisms were Escherichia coli, Psuedomonas spp. and Klebsiella spp. Among the bacterial bloodstream infections, 66% were Gram-negative isolates. MDROs constituted 22% of all isolates in blood cultures. Incidence of resistant Gram-positive organisms was low in the present dataset (methicillin resistant Staphylococcus aureus and vancomycin-resistant enterococci-1.3%. CONCLUSIONS: The analysis reconfirms the Gram-negative organisms as the predominant pathogens in bacteremia seen in patients with hematological cancers. The high frequency of multi-drug resistance in the dataset calls for the need of emergency measures to curtail further development and propagation of resistant organisms.

  11. Determination of physiological, taxonomic, and molecular characteristics of a cultivable arsenic-resistant bacterial community.

    Science.gov (United States)

    Cordi, A; Pagnout, C; Devin, S; Poirel, J; Billard, P; Dollard, M A; Bauda, P

    2015-09-01

    A collection of 219 bacterial arsenic-resistant isolates was constituted from neutral arsenic mine drainage sediments. Isolates were grown aerobically or anaerobically during 21 days on solid DR2A medium using agar or gelan gum as gelling agent, with 7 mM As(III) or 20 mM As(V) as selective pressure. Interestingly, the sum of the different incubation conditions used (arsenic form, gelling agent, oxygen pressure) results in an overall increase of the isolate diversity. Isolated strains mainly belonged to Proteobacteria (63%), Actinobacteria (25%), and Bacteroidetes (10%). The most representative genera were Pseudomonas (20%), Acinetobacter (8%), and Serratia (15%) among the Proteobacteria; Rhodococcus (13%) and Microbacterium (5%) among Actinobacteria; and Flavobacterium (13%) among the Bacteroidetes. Isolates were screened for the presence of arsenic-related genes (arsB, ACR3(1), ACR3(2), aioA, arsM, and arrA). In this way, 106 ACR3(1)-, 74 arsB-, 22 aioA-, 14 ACR3(2)-, and one arsM-positive PCR products were obtained and sequenced. Analysis of isolate sensitivity toward metalloids (arsenite, arsenate, and antimonite) revealed correlations between taxonomy, sensitivity, and genotype. Antimonite sensitivity correlated with the presence of ACR3(1) mainly present in Bacteroidetes and Actinobacteria, and arsenite or antimonite resistance correlated with arsB gene presence. The presence of either aioA gene or several different arsenite carrier genes did not ensure a high level of arsenic resistance in the tested conditions.

  12. Atmospheric pressure resistive barrier air plasma jet induced bacterial inactivation in aqueous environment

    Science.gov (United States)

    Thiyagarajan, Magesh; Sarani, Abdollah; Gonzales, Xavier

    2013-03-01

    An atmospheric pressure resistive barrier air plasma jet is designed to inactivate bacteria in aqueous media in direct and indirect exposure modes of treatment. The resistive barrier plasma jet is designed to operate at both dc and standard 50-60 Hz low frequency ac power input and the ambient air at 50% humidity level was used as the operating gas. The voltage-current characteristics of the plasma jet were analyzed and the operating frequency of the discharge was measured to be 20 kHz and the plasma power was measured to be 26 W. The plasma jet rotational temperatures (Trot) are obtained from the optical emission spectra, from the N2C-B(2+) transitions by matching the experimental spectrum results with the Spectra Air (SPECAIR) simulation spectra. The reactive oxygen and nitrogen species were measured using optical emission spectroscopy and gas analyzers, for direct and indirect treatment modes. The nitric oxides (NO) were observed to be the predominant long lived reactive nitrogen species produced by the plasma. Three different bacteria including Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Neisseria meningitidis (Gram-negative) were suspended in an aqueous media and treated by the resistive barrier air plasma jet in direct and indirect exposure modes. The results show that a near complete bacterial inactivation was achieved within 120 s for both direct and indirect plasma treatment of S. aureus and E. coli bacteria. Conversely, a partial inactivation of N. meningitidis was observed by 120 s direct plasma exposure and insignificant inactivation was observed for the indirect plasma exposure treatment. Plasma induced shifts in N. meningitidis gene expression was analyzed using pilC gene expression as a representative gene and the results showed a reduction in the expression of the pilC gene compared to untreated samples suggesting that the observed protection against NO may be regulated by other genes.

  13. [Profile of bacterial resistance in pediatric urinary tract infections in 2014].

    Science.gov (United States)

    Flammang, A; Morello, R; Vergnaud, M; Brouard, J; Eckart, P

    2017-03-01

    In pediatric units, bacteria-producing extended-spectrum-betalactamase (ESBL) have an increasing prevalence among bacteria causing febrile urinary tract infections (UTIs). The purpose of this study was to evaluate the epidemiology of bacteria resistance patterns observed in UTIs, in order to assess the current antibiotic treatment protocols. This study is based upon a single-center retrospective chart review of the cytobacteriological urine cultures performed in UTIs between 1 January and 31 December 2014, in the medical pediatric unit of the Caen University Hospital. Out of the total of 219 cases of UTI, 26.9% were recurrences of UTI, 18.3% were infections in infants less than 3 months old, 21% of the patients suffered from underlying uropathy, and 16.4% of the patients had recently been exposed to antibiotics. In 80.3% of the cases, Escherichia coli was found, while Enterococcus faecalis was found in 5.6%. The antibiograms proved that 33.5% of the bacteria were sensitive. Half of E. coli were resistant to ampicillin, 4.9% to cefixime, 4.9% to ceftriaxone, 1.1% to gentamicin, and 27.8% to trimethoprim-sulfamethoxazole. Nine E. coli and one Enterobacter cloacae produced ESBL, accounting for 4.6% of the UTIs. We did not find any bacteria-producing high-level cephalosporinase. Cefixime resistance was statistically linked to ongoing antibiotic treatment (OR=5.98; 95% CI [1.44; 24.91], P=0.014) and underlying uropathy (OR=6.24; 95% CI [1.47; 26.42], P=0.013). Ceftriaxone resistance was statistically related to ongoing antibiotic treatment (OR=6.93; 95% CI [1.45; 33.13], P=0.015). These results argue in favor of maintaining intravenous ceftriaxone for probabilistic ambulatory treatment. However, in case of hospitalization, cefotaxime can replace ceftriaxone, due to its lower ecological impact. Moreover, it is necessary to continue monitoring bacterial resistance and regularly review our treatment protocols.

  14. Sulfonamide and tetracycline resistance genes in total- and culturable-bacterial assemblages in South African aquatic environments

    Directory of Open Access Journals (Sweden)

    Satoru eSuzuki

    2015-08-01

    Full Text Available Antibiotic resistant bacteria (ARB are ubiquitous in the natural environment. The introduction of effluent derived antibiotic resistance genes (ARGs into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3 and tet(M, in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP in South Africa. There was no correlation between antibiotic concentrations and ARGs, suggesting the targeted ARGs are spread in a wide area without connection to selection pressure. Among sul genes, sul1 and sul2 were major genes in the total (over 10-2 copies/16S and colony forming bacteria assemblages (approx 10-1 copies/16S. In urban waters, the sul3 gene was mostly not detectable in total and culturable assemblages, suggesting sul3 is not abundant. tet(M was found in natural assemblages with 10-3 copies/16S level in STP, but was not detected in colony forming bacteria, suggesting the non-culturable (yet-to-be cultured bacterial community in urban surface waters and STP effluent possess the tet(M gene. Sulfamethoxazole resistant (SMXr and oxytetracycline resistant (OTCr bacterial communities in urban waters possessed not only sul1 and sul2 but also sul3 and tet(M genes. These genes are widely distributed in SMXr and OTCr bacteria. In conclusion, urban river and estuarine water and STP effluent in the Durban area were highly contaminated with ARGs, and the yet-to-be cultured bacterial community may act as a non-visible ARG reservoir in certain situations.

  15. Antibiotic resistance genes in bacterial and bacteriophage fractions of Tunisian and Spanish wastewaters as markers to compare the antibiotic resistance patterns in each population.

    Science.gov (United States)

    Colomer-Lluch, Marta; Calero-Cáceres, William; Jebri, Sihem; Hmaied, Fatma; Muniesa, Maite; Jofre, Juan

    2014-12-01

    The emergence and increased prevalence of antibiotic resistance genes (ARGs) in the environment may pose a serious global health concern. This study evaluates the abundance of several ARGs in bacterial and bacteriophage DNA via real-time qPCR in samples from five different sampling points in Tunisia; three wastewater treatment plants (WWTP 1, 2 and 3) and wastewater from two abattoirs slaughtering different animals. Results are compared with those obtained in the Barcelona area, in northeast Spain. Eight ARGs were quantified by qPCR from total and phage DNA fraction from the samples. Three β-lactamases (bla(TEM), bla(CTX-M) cluster 1 and bla(CTX-M) cluster 9), two quinolone resistance genes (qnrA and qnrS), the mecA gene that confers resistance to methicillin in Staphylococcus aureus, the emerging armA gene, conferring resistance to aminoglycosides and sul1, the most extended gene conferring resistance to sulfonamides, were evaluated. Sul1 and bla(TEM) were the most prevalent ARGs detected at all five Tunisian sampling points, similarly with the observations in Barcelona. bla(CTX-M-9) was more prevalent than bla(CTX-M-1) both in bacterial and DNA within phage particles in all samples analysed. mecA and armA were almost absent in Tunisian waters from human or animal origin in contrast with Barcelona that showed a medium prevalence. qnrA was more prevalent than qnrS in bacterial and phage DNA from all sampling points. In conclusion, our study shows that ARGs are found in the bacterial and is reflected in the phage DNA fraction of human and animal wastewaters. The densities of each ARGs vary depending on the ARGs shed by each population and is determined by the characteristics of each area. Thus, the evaluation of ARGs in wastewaters seems to be suitable as marker reflecting the antibiotic resistance patterns of a population.

  16. Cultivation and qPCR Detection of Pathogenic and Antibiotic-Resistant Bacterial Establishment in Naive Broiler Houses.

    Science.gov (United States)

    Brooks, J P; McLaughlin, M R; Adeli, A; Miles, D M

    2016-05-01

    Conventional commercial broiler production involves the rearing of more than 20,000 broilers in a single confined space for approximately 6.5 wk. This environment is known for harboring pathogens and antibiotic-resistant bacteria, but studies have focused on previously established houses with mature litter microbial populations. In the current study, a set of three naive houses were followed from inception through 11 broiler flocks and monitored for ambient climatic conditions, bacterial pathogens, and antibiotic resistance. Within the first 3 wk of the first flock cycle, 100% of litter samples were positive for and , whereas was cultivation negative but PCR positive. Antibiotic resistance genes were ubiquitously distributed throughout the litter within the first flock, approaching 10 to 10 genomic units g. Preflock litter levels were approximately 10 CFU g for heterotrophic plate count bacteria, whereas midflock levels were >10 colony forming units (CFU) g; other indicators demonstrated similar increases. The influence of intrahouse sample location was minor. In all likelihood, given that preflock levels were negative for pathogens and antibiotic resistance genes and 4 to 5 Log lower than flock levels for indicators, incoming birds most likely provided the colonizing microbiome, although other sources were not ruled out. Most bacterial groups experienced a cyclical pattern of litter contamination seen in other studies, whereas microbial stabilization required approximately four flocks. This study represents a first-of-its-kind view into the time required for bacterial pathogens and antibiotic resistance to colonize and establish in naive broiler houses.

  17. Defensins couple dysbiosis to primary immunodeficiency in Crohn's disease

    Institute of Scientific and Technical Information of China (English)

    Mathias Chamaillard; Rodrigue Dessein

    2011-01-01

    Antimicrobial peptides, including defensins, are essential effectors in host defence and in the maintenance of immune homeostasis. Clinical studies have linked the defective expression of both α- and β-defensin to the reduced killing of certain microorganisms by the intestinal mucosa of patients suffering from ileal and colonic Crohn's disease (CD), respectively. Only recently have the events leading to defective expression of defensins in CD been further elucidated, and are discussed herein.These events may account for CD-associated alterations in the microbiome and may subsequently precipitate the development of granulomatous inflammatory lesions in genetically-predisposed patients. We also address how these discoveries may pave the way for the development of a molecular medicine aimed at restoring gut barrier function in CD.

  18. Genetic parameters and selection for resistance to bacterial spot in recombinant F6 lines of Capsicum annuum

    Directory of Open Access Journals (Sweden)

    Messias Gonzaga Pereira

    2009-01-01

    Full Text Available This study aimed to advance generations and select superior sweet pepper genotypes with resistance tobacterial spot, using the breeding method Single Seed Descent (SSD based on the segregating population derived from thecross between Capsicum annuum L. UENF 1421 (susceptible, non-pungent and UENF 1381 (resistant, pungent. Thesegregating F3 generation was grown in pots in a greenhouse until the F5 generation. The F6 generation was grown in fieldconditions. The reaction to bacterial spot was evaluated by inoculation with isolate ENA 4135 of Xanthomonas campestris pv.vesicatoria, based on a score scale and by calculating the area under the disease progress curve (AUDPC. The presence orabsence of capsaicin was also assessed. Eighteen F6 lines were bacterial leaf spot-resistant. Since no capsaicin was detectedin the F6 lines 032, 316, 399, 434, and 517, these will be used in the next steps of the sweet pepper breeding program.

  19. Frequency of Bacterial Contamination and Antibiotic Resistance Patterns in Devices and in Personnel of Endoscopy and Colonoscopy Units

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    Torabi, P. (BSc

    2014-06-01

    Full Text Available Background and Objective: This study was aimed to determine the extent of bacterial contamination and drug resistance patterns of isolates colonized in colonoscope and endoscope and in relevant personnel. Material and Methods: A total of 107 samples were obtained from staff of endoscopy and colonoscopy units (SEU and SCU and gastroenterological imaging equipment. For isolation and identification of the bacteria, swab culture method and biochemical identification test were used, respectively. Antimicrobial resistance profiles, multi-drug resistance (MDR patterns and phenetic relatedness of these isolates were also analyzed according to standard methods. Results: Most frequent pathogenic bacteria among the SEU and gastroenterological imaging related equipments were included S. aureus (20.8 % and 0 %; Enterococcus spp. (0 % and 5.4%; Pseudomonas spp. (0% and 13.5 %, and Clostridium difficile (0% and 12.5%. Analysis of resistance phenotypes showed a high frequency of MDR phenotypes among the SEU (82.1%, and also in endoscopes, colonoscopes, and other equipments (20%, 50% and 100%, respectively. Phylotyping of S. epidermidis isolates showed the role of staff in transmission of resistance strains to medical equipments and also circulation of strains with identical resistance phenotype among the studied samples. Conclusion: High frequency of pathogenic bacteria in colonoscopes, endoscopes and in the staff of endoscopy & colonoscopy units, and also contamination of these instruments with MDR pathogens emphasize the need for proper disinfection of endoscopes and colonoscopes and also instruction of staff in these units. Key words: Bacterial Contamination; Endoscope; Colonoscope; Antimicrobial Resistance; Gastrointestinal Disease.

  20. Resistance to ketolide antibiotics by coordinated expression of rRNA methyltransferases in a bacterial producer of natural ketolides.

    Science.gov (United States)

    Almutairi, Mashal M; Park, Sung Ryeol; Rose, Simon; Hansen, Douglas A; Vázquez-Laslop, Nora; Douthwaite, Stephen; Sherman, David H; Mankin, Alexander S

    2015-10-20

    Ketolides are promising new antimicrobials effective against a broad range of Gram-positive pathogens, in part because of the low propensity of these drugs to trigger the expression of resistance genes. A natural ketolide pikromycin and a related compound methymycin are produced by Streptomyces venezuelae strain ATCC 15439. The producer avoids the inhibitory effects of its own antibiotics by expressing two paralogous rRNA methylase genes pikR1 and pikR2 with seemingly redundant functions. We show here that the PikR1 and PikR2 enzymes mono- and dimethylate, respectively, the N6 amino group in 23S rRNA nucleotide A2058. PikR1 monomethylase is constitutively expressed; it confers low resistance at low fitness cost and is required for ketolide-induced activation of pikR2 to attain high-level resistance. The regulatory mechanism controlling pikR2 expression has been evolutionary optimized for preferential activation by ketolide antibiotics. The resistance genes and the induction mechanism remain fully functional when transferred to heterologous bacterial hosts. The anticipated wide use of ketolide antibiotics could promote horizontal transfer of these highly efficient resistance genes to pathogens. Taken together, these findings emphasized the need for surveillance of pikR1/pikR2-based bacterial resistance and the preemptive development of drugs that can remain effective against the ketolide-specific resistance mechanism.

  1. Enteric bacterial pathogens in children with diarrhea in Niger: diversity and antimicrobial resistance.

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    Céline Langendorf

    Full Text Available Although rotavirus is the leading cause of severe diarrhea among children in sub-Saharan Africa, better knowledge of circulating enteric pathogenic bacteria and their antimicrobial resistance is crucial for prevention and treatment strategies.As a part of rotavirus gastroenteritis surveillance in Maradi, Niger, we performed stool culture on a sub-population of children under 5 with moderate-to-severe diarrhea between April 2010 and March 2012. Campylobacter, Shigella and Salmonella were sought with conventional culture and biochemical methods. Shigella and Salmonella were serotyped by slide agglutination. Enteropathogenic Escherichia coli (EPEC were screened by slide agglutination with EPEC O-typing antisera and confirmed by detection of virulence genes. Antimicrobial susceptibility was determined by disk diffusion. We enrolled 4020 children, including 230 with bloody diarrhea. At least one pathogenic bacterium was found in 28.0% of children with watery diarrhea and 42.2% with bloody diarrhea. Mixed infections were found in 10.3% of children. EPEC, Salmonella and Campylobacter spp. were similarly frequent in children with watery diarrhea (11.1%, 9.2% and 11.4% respectively and Shigella spp. were the most frequent among children with bloody diarrhea (22.1%. The most frequent Shigella serogroup was S. flexneri (69/122, 56.5%. The most frequent Salmonella serotypes were Typhimurimum (71/355, 20.0%, Enteritidis (56/355, 15.8% and Corvallis (46/355, 13.0%. The majority of putative EPEC isolates was confirmed to be EPEC (90/111, 81.1%. More than half of all Enterobacteriaceae were resistant to amoxicillin and co-trimoxazole. Around 13% (46/360 Salmonella exhibited an extended-spectrum beta-lactamase phenotype.This study provides updated information on enteric bacteria diversity and antibiotic resistance in the Sahel region, where such data are scarce. Whether they are or not the causative agent of diarrhea, bacterial infections and their antibiotic

  2. Bacteriophage Resistance Mechanisms in the Fish Pathogen Flavobacterium psychrophilum: Linking Genomic Mutations to Changes in Bacterial Virulence Factors

    DEFF Research Database (Denmark)

    Castillo, Daniel; Christiansen, Rói Hammershaimb; Dalsgaard, Inger

    2015-01-01

    Flavobacterium psychrophilum is an important fish pathogen in salmonid aquaculture worldwide. Due to increased antibiotic resistance, pathogen control using bacteriophages has been explored as a possible alternative treatment. However, the effective use of bacteriophages in pathogen control...... requires overcoming the selection for phage resistance in the bacterial populations. Here, we analyzed resistance mechanisms in F. psychrophilum after phage exposure using whole-genome sequencing of the ancestral phage-sensitive strain 950106-1/1 and six phage-resistant isolates. The phage......-resistant strains had all obtained unique insertions and/or deletions and point mutations distributed among intergenic and genic regions. Mutations in genes related to cell surface properties, gliding motility, and biosynthesis of lipopolysaccharides and cell wall were found. The observed links between phage...

  3. Elevated Concentration of Defensins in Hepatitis C Virus-Infected Patients

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    Ehab H. Mattar

    2016-01-01

    Full Text Available Hepatitis C virus (HCV is the major etiological agent of human non-A and non-B hepatitis, affecting around 180 million people worldwide. Defensins, small cysteine-rich cationic peptides, are shown to have potent antibacterial, antiviral, and antifungal properties. Defensins can be found in both normal and microbial infected patients, at variable concentrations. Notably, viral infections are often associated with elevated concentrations of defensins. The current study aimed to estimate the concentrations of total, α-, and β-defensins in serum taken from normal and HCV-infected patients. 12 healthy (noninfected and 34 HCV-infected patients were enrolled. Standardized immunoassay kits were used to obtain serum concentrations of defensins. The obtained results were calibrated against kit standard reagents. Total defensin concentrations in HCV-infected patients were significantly higher (2- to 105-fold compared to healthy individuals. The concentrations of α-defensins were also significantly elevated in the HCV-infected patients (31–1398 ng/50 μL. However, concentrations of β-defensins ranged from 44.5 ng/50 μL to 1056 ng/50 μL. The results did not reveal differences in serum defensin concentration between male and female HCV-infected patients. A-defensin concentration of ≥250 ng/50 μL was found to contain more β-defensins than total defensins and α-defensins. This study concludes, for the first time, that serum defensin levels are elevated in HCV-infected patients.

  4. PREVALENCE AND ANTIBIOTIC RESISTANCE OF FOOD BORNE BACTERIAL CONTAMINATION IN SOME EGYPTIAN FOOD food

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    Samy Selim

    2015-09-01

    Full Text Available This study was undertaken to investigate the prevalence and antibiotic resistance of food borne bacterial contamination in some Egyptian food. Total viable bacteria and total coliform bacteriawere isolated from different sources of food; carbohydrates (bread, flour and basbousa, vegetables (outer and inner tissues of potato and outer and inner tissues of cucumber and proteins (mincedmeat, cheese and milk. The study resulted in maximum value of total viable bacteria found in outer tissue of potato 68X104±1.0, while the minimum value found in inner tissues of potato andcucumber. The study resulted in total coliform was maximum value in minced meat 6.4X103±0.3. Basbousa and inner tissue of potato and cucumber were free from coliforms. The ability of isolatesto producing proteolytic enzymes was tested, we found that 326 isolate (63.92% from all isolates had this ability, thus we selected most 2 potent proteolytic isolates. The two isolates were identifiedas Bacillus cereus and Escherichia coli. The identification confirmed by microlog 34.20 system and 16SrRNA for two isolates and the same result was founded. Sensitivity tested for the most potentproteolytic species to 12 of the most commonly used antibiotics in the Egyptian pharmacy. The results showed that all species were sensitive to most of antibiotics, except B. cereus which was strongly susceptible to azteronam and ceftazidim. The data showed that raw meat, cooked food products, and raw milk were most commonly contaminated with foodborne pathogens and many pathogens were resistant to different antibiotics. The study provided useful information for assessment of the possible risk posed to consumers, which has significant public health impact.

  5. Bacterial resistance to antibiotics in acne vulgaris: An in vitro study

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    Hassanzadeh Parvin

    2008-01-01

    Full Text Available Background: Acne vulgaris is one of the most common skin disorders in youth especially during the puberty. Objective: This in vitro study was performed to determine the antibiotic resistance and sensitivity in acne vulgaris. Materials and Methods: Samples were collected from normal skin and nodulocystic and pustular skin lesions of one hundred youngsters (64 girls, 36 boys among college students in the age range of 18-24 years old. The specimens were cultured individually on blood agar and Muller-Hinton media. The cultures were then incubated under both aerobic and anaerobic conditions for 2 to 7 days. Bacteria were identified and their resistance to common antibiotics was evaluated according to the standard procedures. Results: In aerobic culture of pustular and nodulocystic skin lesions, Staphylococcus aureus was present in 41% of subjects, Staphylococcus epidermidis in 53% and Micrococcus spp in 45% of subjucts. In anaerobic bacterial culture of pustular and nodulocystic skin lesions, Staphylococcus aureus was present in 39%, Propionibacterium acne in 33% and Staphylococcus epidermidis in 21% of subjects. The results of present study revealed that clindamycin and erythromycin were the least effective antibiotics for Propionibacterium acne while tetracycline was the least effective for Staphylococcus aureus in vitro . A synergic effect of benzoyl peroxide, erythromycin or clindamycin was noticed. Rifampin was the most effective antibiotic in vitro . Conclusion: Our results showed that rifampin was the most sensitive antibiotic in vitro for acne vulgaris. To achieve a better treatment, a combination of rifampin with other antibiotics may be more efficient. We suggest in vivo studies for better evaluation and treatment of acne patients with rifampin.

  6. Drug resistance of bacterial dental biofilm and the potential use of natural compounds as alternative for prevention and treatment.

    Science.gov (United States)

    Kouidhi, Bochra; Al Qurashi, Yasir Mohammed A; Chaieb, Kamel

    2015-03-01

    Oral diseases, such as dental caries and periodontal disease are directly linked with the ability of bacteria to form biofilm. The development of dental caries involves acidogenic and aciduric Gram-positive bacteria colonizing the supragingival biofilm (Streptococcus, Lactobacillus and Actinomycetes). Periodontal diseases have been linked to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Cells embedded in biofilm are up to 1000-fold more resistant to antibiotics compared to their planctonic ones. Several mechanisms have been proposed to explain biofilms drug resistance. Given the increased bacterial resistance to antibiotics currently used in dentistry, a great importance is given to natural compounds for the prevention of oral bacterial growth, adhesion and colonization. Over the past decade, interest in drugs derived from medicinal plants has markedly increased. It has been well documented that medicinal plants and natural compounds confer considerable antibacterial activity against various microorganisms including cariogenic and periodontal pathogens. This paper provides a review of the literature focusing on the studies on (i) biofilm in the oral cavity, (ii) drug resistance of bacterial biofilm and (iii) the potential use of plant extracts, essential oils and natural compounds as biofilm preventive agents in dentistry, involving their origin and their mechanism of biofilm inhibition.

  7. Endotoxin, capsule, and bacterial attachment contribute to Neisseria meningitidis resistance to the human antimicrobial peptide LL-37.

    Science.gov (United States)

    Jones, Allison; Geörg, Miriam; Maudsdotter, Lisa; Jonsson, Ann-Beth

    2009-06-01

    Pathogenic bacteria have evolved numerous mechanisms to evade the human immune system and have developed widespread resistance to traditional antibiotics. We studied the human pathogen Neisseria meningitidis and present evidence of novel mechanisms of resistance to the human antimicrobial peptide LL-37. We found that bacteria attached to host epithelial cells are resistant to 10 microM LL-37 whereas bacteria in solution or attached to plastic are killed, indicating that the cell microenvironment protects bacteria. The bacterial endotoxin lipooligosaccharide and the polysaccharide capsule contribute to LL-37 resistance, probably by preventing LL-37 from reaching the bacterial membrane, as more LL-37 reaches the bacterial membrane on both lipooligosaccharide-deficient and capsule-deficient mutants whereas both mutants are also more susceptible to LL-37 killing than the wild-type strain. N. meningitidis bacteria respond to sublethal doses of LL-37 and upregulate two of their capsule genes, siaC and siaD, which further results in upregulation of capsule biosynthesis.

  8. The inflammasomes: Molecular effectors of host resistance against bacterial, viral, parasitic and fungal infections

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    Alexander eSkeldon

    2011-02-01

    Full Text Available The inflammasomes are large multi-protein complexes scaffolded by cytosolic pattern recognition receptors (PRRs that form an important part of the innate immune system. They are activated following the recognition of microbial-associated molecular patterns (MAMPs or host-derived danger signals (danger-associated molecular patterns or DAMPs by PRRs. This recognition results in the recruitment and activation of the pro-inflammatory protease caspase-1, which cleaves its preferred substrates pro-interleukin-1β (IL-1β and pro-IL-18 into their mature biologically active cytokine forms. Through processing of a number of other cellular substrates, caspase-1 is also required for the release of alarmins and the induction and execution of an inflammatory form of cell death termed pyroptosis. A growing spectrum of inflammasomes have been identified in the host defence against a variety of pathogens. Reciprocally, pathogens have evolved effector strategies to antagonize the inflammasome pathway. In this review we discuss recent developments in the understanding of inflammasome-mediated recognition of bacterial, viral, parasitic and fungal infections and the beneficial or detrimental effects of inflammasome signalling in host resistance.

  9. An efficient system for intracellular delivery of beta-lactam antibiotics to overcome bacterial resistance.

    Science.gov (United States)

    Abed, Nadia; Saïd-Hassane, Fatouma; Zouhiri, Fatima; Mougin, Julie; Nicolas, Valérie; Desmaële, Didier; Gref, Ruxandra; Couvreur, Patrick

    2015-08-27

    The "Golden era" of antibiotics is definitely an old story and this is especially true for intracellular bacterial infections. The poor intracellular bioavailability of antibiotics reduces the efficency of many treatments and thereby promotes resistances. Therefore, the development of nanodevices coupled with antibiotics that are capable of targeting and releasing the drug into the infected-cells appears to be a promising solution to circumvent these complications. Here, we took advantage of two natural terpenes (farnesyl and geranyl) to design nanodevices for an efficient intracellular delivery of penicillin G. The covalent linkage between the terpene moieties and the antibiotic leads to formation of prodrugs that self-assemble to form nanoparticles with a high drug payload between 55-63%. Futhermore, the addition of an environmentally-sensitive bond between the antibiotic and the terpene led to an efficient antibacterial activity against the intracellular pathogen Staphylococcus aureus with reduced intracellular replication of about 99.9% compared to untreated infected cells. Using HPLC analysis, we demonstrated and quantified the intracellular release of PenG when this sensitive-bond (SB) was present on the prodrug, showing the success of this technology to deliver antibiotics directly into cells.

  10. Metabolite profiles of rice cultivars containing bacterial blight-resistant genes are distinctive from susceptible rice

    Institute of Scientific and Technical Information of China (English)

    Jiao Wu; Haichuan Yu; Haofu Dai; Wenli Mei; Xin Huang; Shuifang Zhu; Ming Peng

    2012-01-01

    The metabolic changes of bacterial blight-resistant line C418/Xa23 generated by molecular marker-assisted selection (n =12),transgenic variety C418-Xa21 generated by using the Agrobacterium-mediated system (n =12),and progenitor cultivar C418 (n =12) were monitored using gas chromatography/mass spectrometry.The validation,discrimination,and establishment of correlative relationships between metabolite signals were performed by cluster analysis,principal component analysis,and partial least squares-discriminant analysis.Significant and unintended changes were observed in 154 components in C418/Xa23 and 48 components in C418-Xa21 compared with C418 (P < 0.05,Fold change > 2.0).The most significant decreases detected (P< 0.001) in both C418/Xa23 and C418-Xa21 were in three amino acids: glycine,tyrosine,and alanine,and four identified metabolites: malic acid,ferulic acid,succinic acid,and glycerol.Linoleic acid was increased specifically in C418/Xa23 which was derived from traditional breeding.This line,possessing a distinctive metabolite profile as a positive control,shows more differences vs.the parental than the transgenic line.Only succinic acid that falls outside the boundaries of natural variability between the two non-transgenic varieties C418 and C418/Xa23 should be further investigated with respect to safety or nutritional impact.

  11. Effect of different biochars on antibiotic resistance genes and bacterial community during chicken manure composting.

    Science.gov (United States)

    Cui, Erping; Wu, Ying; Zuo, Yiru; Chen, Hong

    2016-03-01

    Rice straw biochar (RSB) and mushroom biochar (MB) were added to lab-scale chicken manure composting to evaluate their effects on the behaviors of antibiotic resistance genes (ARGs) and on total and bio-available heavy metals (Cu, Zn and As). The associated bacterial community was characterized by 16SrRNA high-throughput sequencing. The abundance of pathogenic bacteria was also calculated. At the end of the control composting experiment, the average removal rate of ARGs was 0.86 log units and the removal rate of pathogenic bacteria was 57.1%. MB addition resulted in a higher removal rate than that in the control composting experiment. However, RSB addition yielded opposite results, which may be due to the higher abundance of Erysipelotrichaceae, Lactobacillaceae, Family_XI_Incertae_Sedis (belonging to Firmicutes carrying and disseminating ARGs) and pathogenic bacteria carrying ARGs. Furthermore, the correlations between bio-available heavy metals and ARGs were more obvious than those between total heavy metals and ARGs.

  12. The surface layer of Tannerella forsythia contributes to serum resistance and oral bacterial coaggregation.

    Science.gov (United States)

    Shimotahira, Naohiro; Oogai, Yuichi; Kawada-Matsuo, Miki; Yamada, Sakuo; Fukutsuji, Kenji; Nagano, Keiji; Yoshimura, Fuminobu; Noguchi, Kazuyuki; Komatsuzawa, Hitoshi

    2013-04-01

    Tannerella forsythia is an anaerobic, Gram-negative bacterium involved in the so-called "red complex," which is associated with severe and chronic periodontitis. The surface layer (S-layer) of T. forsythia is composed of cell surface glycoproteins, such as TfsA and TfsB, and is known to play a role in adhesion/invasion and suppression of proinflammatory cytokine expression. Here we investigated the association of this S-layer with serum resistance and coaggregation with other oral bacteria. The growth of the S-layer-deficient mutant in a bacterial medium containing more than 20% non-heat-inactivated calf serum (CS) or more than 40% non-heat-inactivated human serum was significantly suppressed relative to that of the wild type (WT). Next, we used confocal microscopy to perform quantitative analysis on the effect of serum. The survival ratio of the mutant exposed to 100% non-heat-inactivated CS (76% survival) was significantly lower than that of the WT (97% survival). Furthermore, significant C3b deposition was observed in the mutant but not in the WT. In a coaggregation assay, the mutant showed reduced coaggregation with Streptococcus sanguinis, Streptococcus salivarius, and Porphyromonas gingivalis but strong coaggregation with Fusobacterium nucleatum. These results indicated that the S-layer of T. forsythia plays multiple roles in virulence and may be associated with periodontitis.

  13. Who Possesses Drug Resistance Genes in the Aquatic Environment? : Sulfamethoxazole (SMX Resistance Genes among the Bacterial Community in Water Environment of Metro-Manila, Philippines

    Directory of Open Access Journals (Sweden)

    Satoru eSuzuki

    2013-04-01

    Full Text Available Recent evidence has shown that antibiotic resistant bacteria (ARB and antibiotic resistance genes (ARG are ubiquitous in natural environments, including sites considered pristine. To understand the origin of ARGs and their dynamics, we must first define their actual presence in the natural bacterial assemblage. Here we found varying distribution profiles of sul genes in colony forming bacterial assemblages and natural bacterial assemblages. Our monitoring for antibiotic contamination revealed that sulfamethoxazole (SMX is a major contaminant in aquatic environments of Metro-Manila, which would have been derived from human and animal use, and subsequently decreased through the process of outflow from source to the sea. The SMX-resistant bacterial rate evaluated by the colony forming unit showed 10 to 86 % of the total colony numbers showed higher rates from freshwater sites compared to marine sites. When sul genes were quantified by qPCR, colony-forming bacteria conveyed sul1 and sul2 genes in freshwater and seawater (10-5-10-2 copy/16S but not sul3. Among the natural bacterial assemblage, all sul1, sul2 and sul3 were detected (10-5-10-3 copy/16S, whereas all sul genes were at an almost non-detectable level in the freshwater assemblage. This study suggests that sul1 and sul2 are main sul genes in culturable bacteria, whereas sul3 is conveyed by non-culturable bacteria in the sea. As a result marine bacteria possess sul1, sul2 and sul3 genes in the marine environment.

  14. Haemophilus ducreyi SapA contributes to cathelicidin resistance and virulence in humans.

    Science.gov (United States)

    Mount, Kristy L B; Townsend, Carisa A; Rinker, Sherri D; Gu, Xiaoping; Fortney, Kate R; Zwickl, Beth W; Janowicz, Diane M; Spinola, Stanley M; Katz, Barry P; Bauer, Margaret E

    2010-03-01

    Haemophilus ducreyi is an extracellular pathogen of human epithelial surfaces that resists human antimicrobial peptides (APs). The organism's genome contains homologs of genes sensitive to antimicrobial peptides (sap operon) in nontypeable Haemophilus influenzae. In this study, we characterized the sap-containing loci of H. ducreyi 35000HP and demonstrated that sapA is expressed in broth cultures and H. ducreyi-infected tissue; sapA is also conserved among both class I and class II H. ducreyi strains. We constructed a nonpolar sapA mutant of H. ducreyi 35000HP, designated 35000HPsapA, and compared the percent survival of wild-type 35000HP and 35000HPsapA exposed to several human APs, including alpha-defensins, beta-defensins, and the cathelicidin LL-37. Unlike an H. influenzae sapA mutant, strain 35000HPsapA was not more susceptible to defensins than strain 35000HP was. However, we observed a significant decrease in the survival of strain 35000HPsapA after exposure to LL-37, which was complemented by introducing sapA in trans. Thus, the Sap transporter plays a role in resistance of H. ducreyi to LL-37. We next compared mutant strain 35000HPsapA with strain 35000HP for their ability to cause disease in human volunteers. Although both strains caused papules to form at similar rates, the pustule formation rate at sites inoculated with 35000HPsapA was significantly lower than that of sites inoculated with 35000HP (33.3% versus 66.7%; P = 0.007). Together, these data establish that SapA acts as a virulence factor and as one mechanism for H. ducreyi to resist killing by antimicrobial peptides. To our knowledge, this is the first demonstration that an antimicrobial peptide resistance mechanism contributes to bacterial virulence in humans.

  15. Prevalence of antimicrobial resistance among bacterial pathogens isolated from cattle in different European countries: 2002–2004

    Directory of Open Access Journals (Sweden)

    Stärk Katharina

    2008-07-01

    Full Text Available Abstract Background The project "Antibiotic resistance in bacteria of animal origin – II" (ARBAO-II was funded by the European Union (FAIR5-QLK2-2002-01146 for the period 2003–2005, with the aim to establish a continuous monitoring of antimicrobial susceptibility among veterinary laboratories in European countries based on validated and harmonised methodologies. Available summary data of the susceptibility testing of the bacterial pathogens from the different laboratories were collected. Method Antimicrobial susceptibility data for several bovine pathogens were obtained over a three year period (2002–2004. Each year the participating laboratories were requested to fill in excel-file templates with national summary data on the occurrence of antimicrobial resistance from different bacterial species. A proficiency test (EQAS – external quality assurance system for antimicrobial susceptibility testing was conducted each year to test the accuracy of antimicrobial susceptibility testing in the participating laboratories. The data from this testing demonstrated that for the species included in the EQAS the results are comparable between countries. Results Data from 25,241 isolates were collected from 13 European countries. For Staphylococcus aureus from bovine mastitis major differences were apparent in the occurrence of resistance between countries and between the different antimicrobial agents tested. The highest frequency of resistance was observed for penicillin. For Mannheimia haemolytica resistance to ampicillin, tetracycline and trimethoprim/sulphonamide were observed in France, the Netherlands and Portugal. All isolates of Pasteurella multocida isolated in Finland and most of those from Denmark, England (and Wales, Italy and Sweden were susceptible to the majority of the antimicrobials. Streptococcus dysgalactiae and Streptococcus uberis isolates from Sweden were fully susceptible. For the other countries some resistance was observed to

  16. Human beta defensin is absent in burn blister fluid.

    Science.gov (United States)

    Ortega, M R; Ganz, T; Milner, S M

    2000-12-01

    Defensins are a family of cationic antimicrobial peptides that participate in innate host defence. Human beta defensin-2 (HBD-2) is produced by human keratinocytes, and has a potent bactericidal activity against a wide spectrum of microorganisms. We have recently shown that expression of HBD-2 is present in normal skin and lost in the full-thickness burn wound. Defensins have been found in the blister fluid of chronic wounds. Our study was designed to examine blister fluid from partial-thickness burns for defensin content. Fluid from five patients was collected from partial-thickness burn blisters, and then analysed by sandwich Enzyme-Linked Immunosorbent Assay (ELISA) with a monoclonal antibody and rabbit polyclonal antibody to HBD-2. The assay was validated against a Western blot assay for HBD-2 in samples of bronchoalveolar lavage fluid from patients with inflammatory lung disease. No HBD-2 was detectable in any of the burn blister fluids analysed. HBD-2 is lost in the full-thickness burn wound, and we have now demonstrated its absence in burn blister fluid. This finding represents evidence of a host defence defect within the burn wound and suggests a possible therapeutic role for antimicrobial peptides in the management of burn wounds.

  17. Directional and balancing selection in human beta-defensins

    Directory of Open Access Journals (Sweden)

    Armour John AL

    2008-04-01

    Full Text Available Abstract Background In primates, infection is an important force driving gene evolution, and this is reflected in the importance of infectious disease in human morbidity today. The beta-defensins are key components of the innate immune system, with antimicrobial and cell signalling roles, but also reproductive functions. Here we examine evolution of beta-defensins in catarrhine primates and variation within different human populations. Results We show that five beta-defensin genes that do not show copy number variation in humans show evidence of positive selection in catarrhine primates, and identify specific codons that have been under selective pressure. Direct haplotyping of DEFB127 in humans suggests long-term balancing selection: there are two highly diverged haplotype clades carrying different variants of a codon that, in primates, is positively selected. For DEFB132, we show that extensive diversity, including a four-state amino acid polymorphism (valine, isoleucine, alanine and threonine at position 93, is present in hunter-gatherer populations, both African and non-African, but not found in samples from agricultural populations. Conclusion Some, but not all, beta-defensin genes show positive selection in catarrhine primates. There is suggestive evidence of different selective pressures on these genes in humans, but the nature of the selective pressure remains unclear and is likely to differ between populations.

  18. Impact of restricted amoxicillin/clavulanic acid use on Escherichia coli resistance--antibiotic DU90% profiles with bacterial resistance rates: a visual presentation.

    Science.gov (United States)

    Mimica Matanovic, Suzana; Bergman, Ulf; Vukovic, Dubravka; Wettermark, Björn; Vlahovic-Palcevski, Vera

    2010-10-01

    High use of amoxicillin/clavulanic acid (AMC) at the University Hospital Osijek (Croatia) contributed to high rates of resistance in Enterobacteriaceae, in particular Escherichia coli (50%). Thus, in order to decrease bacterial resistance, AMC use was restricted. We present results of the restriction on resistance amongst antibiotics accounting for 90% of antibiotic use [drug utilisation 90% (DU90%)]. Data were analysed on antibiotic use and microbiological susceptibility of E. coli during two 9-month periods, before and after the restriction of AMC use. Drug use was presented as numbers of defined daily doses (DDDs) and DDDs/100 bed-days. Resistance of E. coli to antibiotics was presented as percentages of isolated strains in the DU90% segment. Use of AMC was 16 DDDs/100 bed-days or 30% of all antibiotics before the intervention. Use of AMC fell to 2 DDDs/100 bed-days or 4% after the intervention, and resistance of E. coli fell from 37% to 11%. In conclusion, restricted use of AMC resulted in a significant decrease of E. coli resistance. DU90% resistance profiles are simple and useful tools in highlighting problems in antibiotic use and resistance but may also be useful in long-term follow-up of antibiotic policy.

  19. Transfer of bacterial blight resistance from Oryza meyeriana to O.Sativa L.by asymmetric somatic hybridization

    Institute of Scientific and Technical Information of China (English)

    ZHU Yongsheng; CHEN Baotang; YU Shunwu; ZHANG Duanpin; ZHANG Xueqin; YAN Qiusheng

    2004-01-01

    Asymmetric somatic hybrid plants were produced between cultivated rice (Oryza sativa L.) and wild species [O. Meyeriana (Zoll. etMor, exSteud.)] with high resistance to rice bacterial blight. X-ray-irradiated protoplasts of the wild species were used as donor and chemically fused with iodoacetamide-inactivated protoplasts of rice cv. 02428to produce hybrids. Seventy-two plants were regenerated from 623 calli based on metabolic complementation. The morphological characters of the plants closely resembled that of the rice. Simple sequence repeats were employed to identify their hybridity. Cytological analysis of root-tips revealed that their chromosome number varied in the range of 27-38. The somatic hybrids were inoculated with strains of Xanthamonas oryzae pv. Oryzae at adult growth stage and demonstrated the resistance to bacterial blight introgression from the O. Meyeriana.

  20. Genome-level identification, gene expression, and comparative analysis of porcine ß-defensin genes

    Directory of Open Access Journals (Sweden)

    Choi Min-Kyeung

    2012-11-01

    Full Text Available Abstract Background Beta-defensins (β-defensins are innate immune peptides with evolutionary conservation across a wide range of species and has been suggested to play important roles in innate immune reactions against pathogens. However, the complete β-defensin repertoire in the pig has not been fully addressed. Result A BLAST analysis was performed against the available pig genomic sequence in the NCBI database to identify β-defensin-related sequences using previously reported β-defensin sequences of pigs, humans, and cattle. The porcine β-defensin gene clusters were mapped to chromosomes 7, 14, 15 and 17. The gene expression analysis of 17 newly annotated porcine β-defensin genes across 15 tissues using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR showed differences in their tissue distribution, with the kidney and testis having the largest pBD expression repertoire. We also analyzed single nucleotide polymorphisms (SNPs in the mature peptide region of pBD genes from 35 pigs of 7 breeds. We found 8 cSNPs in 7 pBDs. Conclusion We identified 29 porcine β-defensin (pBD gene-like sequences, including 17 unreported pBDs in the porcine genome. Comparative analysis of β-defensin genes in the pig genome with those in human and cattle genomes showed structural conservation of β-defensin syntenic regions among these species.

  1. Molecular characterization of conjugative plasmids in pesticide tolerant and multi-resistant bacterial isolates from contaminated alluvial soil.

    Science.gov (United States)

    Anjum, Reshma; Grohmann, Elisabeth; Malik, Abdul

    2011-06-01

    A total of 35 bacteria from contaminated soil (cultivated fields) near pesticide industry from Chinhat, Lucknow, (India) were isolated and tested for their tolerance/resistance to pesticides, heavy metals and antibiotics. Bacterial isolates were identified by 16S rDNA sequencing. Gas Chromatography analysis of the soil samples revealed the presence of lindane at a concentration of 547 ng g(-1) and α-endosulfan and β-endosulfan of 422 ng g(-1) and 421 ng g(-1) respectively. Atomic Absorption Spectrophotometry analysis of the test sample was done and Cr, Zn, Ni, Fe, Cu and Cd were detected at concentrations of 36.2, 42.5, 43.2, 241, 13.3 and 11.20 mg kg(-1) respectively. Minimum inhibitory concentrations of all the isolates were determined for pesticides and heavy metals. All the multi-resistant/tolerant bacterial isolates were also tested for the presence of incompatibility (Inc) group IncP, IncN, IncW, IncQ plasmids and for rolling circle plasmids of the pMV158-family by PCR. Total community DNA was extracted from pesticide contaminated soil. PCR amplification of the bacterial isolates and soil DNA revealed the presence of IncP-specific sequences (trfA2 and oriT) which was confirmed by dot blot hybridization with RP4-derived DIG-labelled probes. Plasmids belonging to IncN, IncW and IncQ group were neither detected in the bacterial isolates nor in total soil DNA. The presence of conjugative or mobilizable IncP plasmids in the isolates indicate that these bacteria have gene transfer capacity with implications for dissemination of heavy metal and antibiotic resistance genes. We propose that IncP plasmids are mainly responsible for the spread of multi-resistant bacteria in the contaminated soils.

  2. Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs

    OpenAIRE

    Geisla Mary Silva Soares; Luciene Cristina de Figueiredo; Marcelo Faveri; Sheila Cavalca Cortelli; Poliana Mendes Duarte; Magda Feres

    2012-01-01

    Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibio...

  3. Comparative analysis of bacterial community and antibiotic-resistant strains in different developmental stages of the housefly (Musca domestica).

    Science.gov (United States)

    Wei, Ting; Hu, Jun; Miyanaga, Kazuhiko; Tanji, Yasunori

    2013-02-01

    The housefly (Musca domestica) is an important host for a variety of bacteria, including some pathogenic and antibiotic-resistant strains. To further investigate the relationship between the housefly and the bacteria it harbors, it is necessary to understand the fate of microorganisms during the larval metamorphosis. The major bacterial communities in three developmental stages of the housefly (maggot, pupa, and adult fly) were investigated by a culture-independent method, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA genes. The bacteria that were identified using DGGE analysis spanned phyla Proteobacteria, Firmicutes, and Bacteroidetes. Changes in the predominant genera were observed during the housefly development. Bacteroides, Koukoulia, and Schineria were detected in maggots, Neisseria in pupae, and Macrococcus, Lactococcus, and Kurthia in adult flies. Antibiotic-resistant bacteria were screened using a selective medium and tested for antibiotic susceptibility. Most resistant isolates from maggots and pupae were classified as Proteus spp., while those from adult flies were much more diverse and spanned 12 genera. Among 20 tested strains across the three stages, 18 were resistant to at least two antibiotics. Overall, we demonstrated that there are changes in the major bacterial communities and antibiotic-resistant strains as the housefly develops.

  4. Sludge as a potential important source of antibiotic resistance genes in both the bacterial and bacteriophage fractions.

    Science.gov (United States)

    Calero-Cáceres, William; Melgarejo, Ana; Colomer-Lluch, Marta; Stoll, Claudia; Lucena, Francisco; Jofre, Juan; Muniesa, Maite

    2014-07-01

    The emergence and prevalence of antibiotic resistance genes (ARGs) in the environment is a serious global health concern. ARGs found in bacteria can become mobilized in bacteriophage particles in the environment. Sludge derived from secondary treatment in wastewater treatment plants (WWTPs) constitutes a concentrated pool of bacteria and phages that are removed during the treatment process. This study evaluates the prevalence of ARGs in the bacterial and phage fractions of anaerobic digested sludge; five ARGs (blaTEM, blaCTX-M, qnrA, qnrS, and sul1) are quantified by qPCR. Comparison between the wastewater and sludge revealed a shift in the prevalence of ARGs (blaTEM and sul1 became more prevalent in sludge), suggesting there is a change in the bacterial and phage populations from wastewater to those selected during the secondary treatment and the later anaerobic mesophilic digestion of the sludge. ARGs densities were higher in the bacterial than in the phage fraction, with high densities in both fractions; particularly for blaTEM and sul1 (5 and 8 log10 gene copies (GC)/g, respectively, in bacterial DNA; 5.5 and 4.4 log10 GC/g, respectively, in phage DNA). These results question the potential agricultural uses of treated sludge, as it could contribute to the spread of ARGs in the environment and have an impact on the bacterial communities of the receiving ecosystem.

  5. Innate Defense against Influenza A Virus: Activity of Human Neutrophil Defensins and Interactions of Defensins with Surfactant Protein D

    DEFF Research Database (Denmark)

    Hartshorn, Kevan L.; White, Mitchell R.; Tecle, Tesfaldet;

    2006-01-01

    Surfactant protein D (SP-D) plays important roles in innate host defense against influenza A virus (IAV) infection, in part by modifying interactions with neutrophils. Human neutrophil defensins (HNPs) inhibit infectivity of enveloped viruses, including IAV. Our goal in this study...

  6. Exposure of the grass shrimp, Palaemonetes pugio, to antimicrobial compounds affects associated Vibrio bacterial density and development of antibiotic resistance.

    Science.gov (United States)

    DeLorenzo, M E; Brooker, J; Chung, K W; Kelly, M; Martinez, J; Moore, J G; Thomas, M

    2016-04-01

    Antimicrobial compounds are widespread, emerging contaminants in the aquatic environment and may threaten ecosystem and human health. This study characterized effects of antimicrobial compounds common to human and veterinary medicine, aquaculture, and consumer personal care products [erythromycin (ERY), sulfamethoxazole (SMX), oxytetracycline (OTC), and triclosan (TCS)] in the grass shrimp Palaemonetes pugio. The effects of antimicrobial treatments on grass shrimp mortality and lipid peroxidation activity were measured. The effects of antimicrobial treatments on the bacterial community of the shrimp were then assessed by measuring Vibrio density and testing bacterial isolates for antibiotic resistance. TCS (0.33 mg/L) increased shrimp mortality by 37% and increased lipid peroxidation activity by 63%. A mixture of 0.33 mg/L TCS and 60 mg/L SMX caused a 47% increase in shrimp mortality and an 88% increase in lipid peroxidation activity. Exposure to SMX (30 mg/L or 60 mg/L) alone and to a mixture of SMX/ERY/OTC did not significantly affect shrimp survival or lipid peroxidation activity. Shrimp exposure to 0.33 mg/L TCS increased Vibrio density 350% as compared to the control whereas SMX, the SMX/TCS mixture, and the mixture of SMX/ERY/OTC decreased Vibrio density 78-94%. Increased Vibrio antibiotic resistance was observed for all shrimp antimicrobial treatments except for the mixture of SMX/ERY/OTC. Approximately 87% of grass shrimp Vibrio isolates displayed resistance to TCS in the control treatment suggesting a high level of TCS resistance in environmental Vibrio populations. The presence of TCS in coastal waters may preferentially increase the resistance and abundance of pathogenic bacteria. These results indicate the need for further study into the potential interactions between antimicrobials, aquatic organisms, and associated bacterial communities.

  7. High level multiple antibiotic resistance among fish surface associated bacterial populations in non-aquaculture freshwater environment.

    Science.gov (United States)

    Ozaktas, Tugba; Taskin, Bilgin; Gozen, Ayse G

    2012-12-01

    Freshwater fish, Alburnus alburnus (bleak), were captured from Lake Mogan, situated in Ankara, during spring. The surface mucus of the fish was collected and associated bacteria were cultured and isolated. By sequencing PCR-amplified 16S RNA encoding genes, the isolates were identified as members of 12 different genera: Acinetobacter, Aeromonas, Bacillus, Brevundimonas, Gordonia, Kocuria, Microbacterium, Mycobacterium, Pseudomonas, Rhodococcus, and Staphylococcus, in addition to one strain that was unidentified. The mucus-dwelling bacterial isolates were tested for resistance against ampicillin, kanamycin, streptomycin and chloramphenicol. About 95% of the isolates were found to be resistant to ampicillin, 93% to chloramphenicol, and 88% to kanamycin and streptomycin. A Microbacterium oxydans and the unidentified environmental isolate were resistant to all four antibiotics tested at very high levels (>1600 μg/ml ampicillin and streptomycin; >1120 μg/ml kanamycin; >960 μg/ml chloramphenicol). Only a Kocuria sp. was sensitive to all four antibiotics at the lowest concentrations tested (3.10 μg/ml ampicillin and streptomycin; 2.15 μg/ml kanamycin; 1.85 μg/ml chloramphenicol). The rest of the isolates showed different resistance levels. Plasmid isolations were carried out to determine if the multiple antibiotic resistance could be attributed to the presence of plasmids. However, no plasmid was detected in any of the isolates. The resistance appeared to be mediated by chromosome-associated functions. This study indicated that multiple antibiotic resistance at moderate to high levels is common among the current phenotypes of the fish mucus-dwelling bacterial populations in this temperate, shallow lake which has not been subjected to any aquaculturing so far but under anthropogenic effect being in a recreational area.

  8. Expression of an evolved engineered variant of a bacterial glycine oxidase leads to glyphosate resistance in alfalfa.

    Science.gov (United States)

    Nicolia, A; Ferradini, N; Molla, G; Biagetti, E; Pollegioni, L; Veronesi, F; Rosellini, D

    2014-08-20

    The main strategy for resistance to the herbicide glyphosate in plants is the overexpression of an herbicide insensitive, bacterial 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). A glyphosate resistance strategy based on the ability to degrade the herbicide can be useful to reduce glyphosate phytotoxicity to the crops. Here we present the characterization of glyphosate resistance in transgenic alfalfa (Medicago sativa L.) expressing a plant-optimized variant of glycine oxidase (GO) from Bacillus subtilis, evolved in vitro by a protein engineering approach to efficiently degrade glyphosate. Two constructs were used, one with (GO(TP+)) and one without (GO(TP-)) the pea rbcS plastid transit peptide. Molecular and biochemical analyses confirmed the stable integration of the transgene and the correct localization of the plastid-imported GO protein. Transgenic alfalfa plants were tested for glyphosate resistance both in vitro and in vivo. Two GO(TP+) lines showed moderate resistance to the herbicide in both conditions. Optimization of expression of this GO variant may allow to attain sufficient field resistance to glyphosate herbicides, thus providing a resistance strategy based on herbicide degradation.

  9. Pre-adapting parasitic phages to a pathogen leads to increased pathogen clearance and lowered resistance evolution with Pseudomonas aeruginosacystic fibrosis bacterial isolates

    DEFF Research Database (Denmark)

    Friman, Ville-Petri; Soanes-Brown, Daniel; Sierocinski, Pawel

    2016-01-01

    Recent years have seen renewed interest in phage therapy - the use of viruses to specifically kill disease-causing bacteria – because of the alarming rise in antibiotic resistance. However, a major limitation of phage therapy is the ease at with bacteria can evolve resistance to phages. Here we...... determined if in vitro experimental coevolution can increase the efficiency of phage therapy by limiting the resistance evolution of intermittent and chronic cystic fibrosis Pseudomonas aeruginosa lung isolates to four different phages. We first pre-adapted all phage strains against all bacterial strains...... and then compared the efficacy of pre-adapted and non-adapted phages against ancestral bacterial strains. We found that evolved phages were more efficient in reducing bacterial densities than ancestral phages. This was primarily because only 50% of bacterial strains were able to evolve resistance to evolved phages...

  10. Defending the fort: a role for defensin-2 in limiting Rickettsia montanensis infection of Dermacentor variabilis.

    Science.gov (United States)

    Pelc, R S; McClure, J C; Sears, K T; Chung, A; Rahman, M S; Ceraul, S M

    2014-08-01

    The importance of tick defensins is evidenced by their expression in a wide variety of tick tissues and prevalence across many tick genera. To date, the functional and biological significance of defensin-2 as a rickettsiastatic or rickettsiacidal antimicrobial peptide has not been addressed. In a previous study, defensin-2 transcription was shown to increase in Dermacentor variabilis ticks challenged with Rickettsia montanensis. In the present study, the hypothesis that defensin-2 is functional as a rickettsiastatic and/or rickettsiacidal antimicrobial peptide is tested. We show that defensin-2 plays a role in reducing burden after acquisition of Rickettsia montanensis through capillary feeding. Moreover, defensin-2 is shown to associate with R. montanensis in vitro and in vivo, causing cytoplasmic leakiness.

  11. Bacterial flora and antibiotic resistance from eggs of green turtles Chelonia mydas: an indication of polluted effluents.

    Science.gov (United States)

    Al-Bahry, Saif; Mahmoud, Ibrahim; Elshafie, Abdulkader; Al-Harthy, Asila; Al-Ghafri, Sabha; Al-Amri, Issa; Alkindi, Abdulaziz

    2009-05-01

    Sea turtles migrate to various habitats where they can be exposed to different pollutants. Bacteria were collected from turtle eggs and their resistance to antibiotics was used as pollutant bio-indicators of contaminated effluents. Eggs were collected randomly from turtles when they were laying their eggs. A total of 90 eggs were collected and placed into sterile plastic bags (3 eggs/turtle) during June-December of 2003. The bacteria located in the eggshell, albumen and yolk were examined, and 42% of the eggs were contaminated with 10 genera of bacteria. Pseudomonas spp. were the most frequent isolates. The albumen was found to be the part of the egg to be the least contaminated by bacterial infection. Bacterial isolates tested with 14 antibiotics showed variations in resistance. Resistance to ampicillin was the highest. The presence of antibiotic resistant bacteria in eggs indicates that the green turtle populations were subjected to polluted effluents during some of their migratory routes and feeding habitats. Scanning electron microscopy revealed that Salmonella typhimurium penetrated all eggshell layers.

  12. "DETECTION OF BACTERIAL, METHICILLIN RESISTANCE, AND β-LACTAMASE GENES FOUND IN WOUND SWABS BY MULTIPLEX POLYMERASE CHAIN REACTION"

    Directory of Open Access Journals (Sweden)

    S. Sadeghian

    2004-05-01

    Full Text Available Coagulase-positive and coagulase negative, methicillin-resistant staphylococci are major causes of serious nosocomial infections and it is very important to have a reliable test to detect these bacteria. A multiplex polymerase chain reaction (mPCR was used on 100 clinical samples for simultaneous amplification of the universal bacterial, mec-A encoding the penicillin binding protein 2a, which is associated with staphylococcal methicillin resistance and TEM-1 encoding the β-lactamase, which accounts for the majority of all cases of the plasmid β-lactamase resistance worldwide. Out of 100 wound swabs tested, 99% with universal primers, 26% with TEM-1 primers and 6% with mec-A primers were positive. Dot blot Digoxigenin hybridization on the 30 samples was carried out to confirm identified bacteria with specific bacterial probes. Out of 100 wound swabs, 38% were positive with Staphylococcus aureus probe, 23% were positive with enteric bacteria probe, 7% were positive with Streptococcus agalactia probe and 1% were positive with Haemophilus influenza probe. The mPCR method used in this study, was designed to be incorporated into the workflow of the clinical microbiology laboratory and allows for the identification of intrinsic resistance in a timely and reliable manner.

  13. Prevalence of antimicrobial resistance among bacterial pathogens isolated from cattle in different European countries: 2002–2004

    DEFF Research Database (Denmark)

    Hendriksen, Rene S.; Mevius, Dik J; Schroeter, Andreas

    2008-01-01

    Background: The project "Antibiotic resistance in bacteria of animal origin - II" (ARBAO-II) was funded by the European Union (FAIR5-QLK2-2002-01146) for the period 2003 - 2005, with the aim to establish a continuous monitoring of antimicrobial susceptibility among veterinary laboratories...... in European countries based on validated and harmonised methodologies. Available summary data of the susceptibility testing of the bacterial pathogens from the different laboratories were collected. Method: Antimicrobial susceptibility data for several bovine pathogens were obtained over a three year period...... from 13 European countries. For Staphylococcus aureus from bovine mastitis major differences were apparent in the occurrence of resistance between countries and between the different antimicrobial agents tested. The highest frequency of resistance was observed for penicillin. For Mannheimia haemolytica...

  14. Breeding Rice Restorer Lines with High Resistance to Bacterial Blight by Using Molecular Marker-Assisted Selection

    Institute of Scientific and Technical Information of China (English)

    DENG Qi-ming; WANG Shi-quan; ZHENG Ai-ping; ZHANG Hong-yu; LI Ping

    2006-01-01

    Two bacterial blight (BB) resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through testing the R target genes with molecular markers and analyzing parental genetic background. Inoculation of the four lines and their hybrids with the specific strains of Xanthomonas oryzae pv. oryzae, P1, P6 and seven representative strains of Chinese pathotype, C Ⅰ -CⅦ, showed that all of the four lines and their hybrids were highly resistant and presented broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potential, and R207-2 was named Shuhui 207.

  15. Expression and antimicrobial function of beta-defensin 1 in the lower urinary tract.

    Directory of Open Access Journals (Sweden)

    Brian Becknell

    Full Text Available Beta defensins (BDs are cationic peptides with antimicrobial activity that defend epithelial surfaces including the skin, gastrointestinal, and respiratory tracts. However, BD expression and function in the urinary tract are incompletely characterized. The purpose of this study was to describe Beta Defensin-1 (BD-1 expression in the lower urinary tract, regulation by cystitis, and antimicrobial activity toward uropathogenic Escherichia coli (UPEC in vivo. Human DEFB1 and orthologous mouse Defb1 mRNA are detectable in bladder and ureter homogenates, and human BD-1 protein localizes to the urothelium. To determine the relevance of BD-1 to lower urinary tract defense in vivo, we evaluated clearance of UPEC by Defb1 knockout (Defb1(-/- mice. At 6, 18, and 48 hours following transurethral UPEC inoculation, no significant differences were observed in bacterial burden in bladders or kidneys of Defb1(-/- and wild type C57BL/6 mice. In wild type mice, bladder Defb1 mRNA levels decreased as early as two hours post-infection and reached a nadir by six hours. RT-PCR profiling of BDs identified expression of Defb3 and Defb14 mRNA in murine bladder and ureter, which encode for mBD-3 and mBD-14 protein, respectively. MBD-14 protein expression was observed in bladder urothelium following UPEC infection, and both mBD-3 and mBD-14 displayed dose-dependent bactericidal activity toward UPEC in vitro. Thus, whereas mBD-1 deficiency does not alter bladder UPEC burden in vivo, we have identified mBD-3 and mBD-14 as potential mediators of mucosal immunity in the lower urinary tract.

  16. A locked nucleic acid (LNA-based real-time PCR assay for the rapid detection of multiple bacterial antibiotic resistance genes directly from positive blood culture.

    Directory of Open Access Journals (Sweden)

    Lingxiang Zhu

    Full Text Available Bacterial strains resistant to various antibiotic drugs are frequently encountered in clinical infections, and the rapid identification of drug-resistant strains is highly essential for clinical treatment. We developed a locked nucleic acid (LNA-based quantitative real-time PCR (LNA-qPCR method for the rapid detection of 13 antibiotic resistance genes and successfully used it to distinguish drug-resistant bacterial strains from positive blood culture samples. A sequence-specific primer-probe set was designed, and the specificity of the assays was assessed using 27 ATCC bacterial strains and 77 negative blood culture samples. No cross-reaction was identified among bacterial strains and in negative samples, indicating 100% specificity. The sensitivity of the assays was determined by spiking each bacterial strain into negative blood samples, and the detection limit was 1-10 colony forming units (CFU per reaction. The LNA-qPCR assays were first applied to 72 clinical bacterial isolates for the identification of known drug resistance genes, and the results were verified by the direct sequencing of PCR products. Finally, the LNA-qPCR assays were used for the detection in 47 positive blood culture samples, 19 of which (40.4% were positive for antibiotic resistance genes, showing 91.5% consistency with phenotypic susceptibility results. In conclusion, LNA-qPCR is a reliable method for the rapid detection of bacterial antibiotic resistance genes and can be used as a supplement to phenotypic susceptibility testing for the early detection of antimicrobial resistance to allow the selection of appropriate antimicrobial treatment and to prevent the spread of resistant isolates.

  17. Characterization of hypersensitive resistance to bacterial spot race T3 (Xanthomonas perforans) from tomato accession PI 128216.

    Science.gov (United States)

    Robbins, Matthew D; Darrigues, Audrey; Sim, Sung-Chur; Masud, Mohammed Abu Taher; Francis, David M

    2009-09-01

    Bacterial spot of tomato is caused by four species of Xanthomonas. The accession PI 128216 (Solanum pimpinellifolium) displays a hypersensitive reaction (HR) to race T3 strains (predominantely Xanthomonas perforans). We developed an inbred backcross (IBC) population (BC(2)S(5), 178 families) derived from PI 128216 and OH88119 (S. lycopersicum) as the susceptible recurrent parent for simultaneous introgression and genetic analysis of the HR response. These IBC families were evaluated in the greenhouse for HR to race T3 strain Xcv761. The IBC population was genotyped with molecular markers distributed throughout the genome in order to identify candidate loci conferring resistance. We treated the IBC population as a hypothesis forming generation to guide validation in subsequent crosses. Nonparametric analysis identified an association between HR and markers clustered on chromosome 11 (P P > 0.002). Further analysis of the IBC population suggested that markers on chromosome 6 and 11 failed to assort independently, a phenomenon known as gametic phase disequilibrium. Therefore, to validate marker-trait linkages, resistant IBC plants were crossed with OH88119 and BC(3)F(2) progeny were evaluated for HR in the greenhouse. In these subsequent populations, the HR response was associated with the chromosome 11 markers (P 0.25). Independent F(2) families were developed by crossing resistant IBC lines to OH8245, OH88119, and OH7530. These populations were genotyped, organized into classes based on chromosome 11 markers, and evaluated for resistance in the field. The PI 128216 locus on chromosome 11 provided resistance that was dependent on gene dosage and genetic background. These results define a single locus, Rx-4, from PI 128216, which provides resistance to bacterial spot race T3, has additive gene action, and is located on chromosome 11.

  18. Prevalence of antibiotic resistance genes and bacterial community composition in a river influenced by a wastewater treatment plant.

    Directory of Open Access Journals (Sweden)

    Elisabet Marti

    Full Text Available Antibiotic resistance represents a global health problem, requiring better understanding of the ecology of antibiotic resistance genes (ARGs, their selection and their spread in the environment. Antibiotics are constantly released to the environment through wastewater treatment plant (WWTP effluents. We investigated, therefore, the effect of these discharges on the prevalence of ARGs and bacterial community composition in biofilm and sediment samples of a receiving river. We used culture-independent approaches such as quantitative PCR to determine the prevalence of eleven ARGs and 16S rRNA gene-based pyrosequencing to examine the composition of bacterial communities. Concentration of antibiotics in WWTP influent and effluent were also determined. ARGs such as qnrS, bla TEM, bla CTX-M, bla SHV, erm(B, sul(I, sul(II, tet(O and tet(W were detected in all biofilm and sediment samples analyzed. Moreover, we observed a significant increase in the relative abundance of ARGs in biofilm samples collected downstream of the WWTP discharge. We also found significant differences with respect to community structure and composition between upstream and downstream samples. Therefore, our results indicate that WWTP discharges may contribute to the spread of ARGs into the environment and may also impact on the bacterial communities of the receiving river.

  19. Inhibition of bacterial growth by iron oxide nanoparticles with and without attached drug: Have we conquered the antibiotic resistance problem?

    Science.gov (United States)

    Armijo, Leisha M.; Jain, Priyanka; Malagodi, Angelina; Fornelli, F. Zuly; Hayat, Allison; Rivera, Antonio C.; French, Michael; Smyth, Hugh D. C.; Osiński, Marek

    2015-03-01

    Pseudomonas aeruginosa is among the top three leading causative opportunistic human pathogens, possessing one of the largest bacterial genomes and an exceptionally large proportion of regulatory genes therein. It has been known for more than a decade that the size and complexity of the P. aeruginosa genome is responsible for the adaptability and resilience of the bacteria to include its ability to resist many disinfectants and antibiotics. We have investigated the susceptibility of P. aeruginosa bacterial biofilms to iron oxide (magnetite) nanoparticles (NPs) with and without attached drug (tobramycin). We also characterized the susceptibility of zero-valent iron NPs, which are known to inactivate microbes. The particles, having an average diameter of 16 nm were capped with natural alginate, thus doubling the hydrodynamic size. Nanoparticle-drug conjugates were produced via cross-linking drug and alginate functional groups. Drug conjugates were investigated in the interest of determining dosage, during these dosage-curve experiments, NPs unbound to drug were tested in cultures as a negative control. Surprisingly, we found that the iron oxide NPs inhibited bacterial growth, and thus, biofilm formation without the addition of antibiotic drug. The inhibitory dosages of iron oxide NPs were investigated and the minimum inhibitory concentrations are presented. These findings suggest that NP-drug conjugates may overcome the antibiotic drug resistance common in P. aeruginosa infections.

  20. Fate of tetracycline, sulfonamide and fluoroquinolone resistance genes and the changes in bacterial diversity during composting of swine manure.

    Science.gov (United States)

    Selvam, Ammaiyappan; Xu, Delin; Zhao, Zhenyong; Wong, Jonathan W C

    2012-12-01

    This study monitored the abundance of antibiotic resistant genes (ARGs) and the bacterial diversity during composting of swine manure spiked with chlortetracycline, sulfadiazine and ciprofloxacin at two different levels and a control without antibiotics. Resistance genes of tetracycline (tetQ, tetW, tetC, tetG, tetZ and tetY), sulfonamide (sul1, sul2, dfrA1 and dfrA7) and fluoroquinolone (gyrA and parC) represented 0.02-1.91%, 0.67-10.28% and 0.00005-0.0002%, respectively, of the total 16S rDNA copies in the initial composting mass. After 28-42 days of composting, these ARGs, except parC, were undetectable in the composting mass indicating that composting is a potential method of manure management. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis of bacterial 16S rDNA of the composting mass indicated that the addition of antibiotics up to 100, 20 and 20mg/kg of chlortetracycline, sulfadiazine and ciprofloxacin, respectively, elicited only a transient perturbation and the bacterial diversity was restored in due course of composting.

  1. The two-component signal transduction system YvcPQ regulates the bacterial resistance to bacitracin in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Shumeng; Li, Xinfeng; Wang, Xun; Li, Zhou; He, Jin

    2016-10-01

    YvcPQ is one of the two-component signal transduction systems that respond to specific stimuli and enable cells to adjust multiple cellular functions. It consists of a histidine kinase YvcQ and a response regulator YvcP. In this study, through searching the consensus sequence recognized by YvcP, we found four YvcP-binding motifs in the promoter regions of genes yvcR (BMB171_C4100), BMB171_C4385, kapD (BMB171_C4525) and BMB171_C4835 in Bacillus thuringiensis BMB171 which is a representative of Bacillus cereus group, and confirmed that these genes are regulated by YvcP. We compared the sequence of yvcPQ and its downstream genes in genus Bacillus, and found two different kinds of yvc locus, one was the yvcPQ-RS in B. subtilis species and the other was the yvcPQ-R-S1S2 in B. cereus group. Furthermore, we found that YvcP activates the transcription of yvcS1S2 (downstream of yvcR) to promote bacterial resistance to bacitracin and deletion of either yvcPQ operon or yvcS1S2 operon renders the bacterial cells more sensitive to bacitracin. This study enriched our understanding of both the YvcPQ's function and the mechanism of bacterial resistance to bacitracin.

  2. Understanding the origins of bacterial resistance to aminoglycosides through molecular dynamics mutational study of the ribosomal A-site.

    Directory of Open Access Journals (Sweden)

    Julia Romanowska

    2011-07-01

    Full Text Available Paromomycin is an aminoglycosidic antibiotic that targets the RNA of the bacterial small ribosomal subunit. It binds in the A-site, which is one of the three tRNA binding sites, and affects translational fidelity by stabilizing two adenines (A1492 and A1493 in the flipped-out state. Experiments have shown that various mutations in the A-site result in bacterial resistance to aminoglycosides. In this study, we performed multiple molecular dynamics simulations of the mutated A-site RNA fragment in explicit solvent to analyze changes in the physicochemical features of the A-site that were introduced by substitutions of specific bases. The simulations were conducted for free RNA and in complex with paromomycin. We found that the specific mutations affect the shape and dynamics of the binding cleft as well as significantly alter its electrostatic properties. The most pronounced changes were observed in the U1406C∶U1495A mutant, where important hydrogen bonds between the RNA and paromomycin were disrupted. The present study aims to clarify the underlying physicochemical mechanisms of bacterial resistance to aminoglycosides due to target mutations.

  3. Copper amendment of agricultural soil selects for bacterial antibiotic resistance in the field

    DEFF Research Database (Denmark)

    Berg, J.; Tom-Petersen, A.; Nybroe, O.

    2005-01-01

    Aims: The objective of this study was to determine whether Cu-amendment of field plots affects the frequency of Cu resistance, and antibiotic resistance patterns in indigenous soil bacteria. Methods and Results: Soil bacteria were isolated from untreated and Cu-amended field plots. Cu......-amendment significantly increased the frequency of Cu-resistant isolates. A panel of isolates were characterized by Gram-reaction, amplified ribosomal DNA restriction analysis and resistance profiling against seven antibiotics. More than 95% of the Cu-resistant isolates were Gram-negative. Cu-resistant Gram......-negative isolates had significantly higher incidence of resistance to ampicillin, sulphanilamide and multiple (greater than or equal to3) antibiotics than Cu-sensitive Gram-negative isolates. Furthermore, Cu-resistant Gram-negative isolates from Cu-contaminated plots had significantly higher incidence of resistance...

  4. The population genetics of drug resistance evolution in natural populations of viral, bacterial and eukaryotic pathogens.

    Science.gov (United States)

    Wilson, Benjamin A; Garud, Nandita R; Feder, Alison F; Assaf, Zoe J; Pennings, Pleuni S

    2016-01-01

    Drug resistance is a costly consequence of pathogen evolution and a major concern in public health. In this review, we show how population genetics can be used to study the evolution of drug resistance and also how drug resistance evolution is informative as an evolutionary model system. We highlight five examples from diverse organisms with particular focus on: (i) identifying drug resistance loci in the malaria parasite Plasmodium falciparum using the genomic signatures of selective sweeps, (ii) determining the role of epistasis in drug resistance evolution in influenza, (iii) quantifying the role of standing genetic variation in the evolution of drug resistance in HIV, (iv) using drug resistance mutations to study clonal interference dynamics in tuberculosis and (v) analysing the population structure of the core and accessory genome of Staphylococcus aureus to understand the spread of methicillin resistance. Throughout this review, we discuss the uses of sequence data and population genetic theory in studying the evolution of drug resistance.

  5. Monitoring bacterial resistance to chloramphenicol and other antibiotics by liquid chromatography electrospray ionization tandem mass spectrometry using selected reaction monitoring.

    Science.gov (United States)

    Haag, Anthony M; Medina, Audrie M; Royall, Ariel E; Herzog, Norbert K; Niesel, David W

    2013-06-01

    Antibiotic resistance is a growing problem worldwide. For this reason, clinical laboratories often determine the susceptibility of the bacterial isolate to a number of different antibiotics in order to establish the most effective antibiotic for treatment. Unfortunately, current susceptibility assays are time consuming. Antibiotic resistance often involves the chemical modification of an antibiotic to an inactive form by an enzyme expressed by the bacterium. Selected reaction monitoring (SRM) has the ability to quickly monitor and identify these chemical changes in an unprecedented time scale. In this work, we used SRM as a technique to determine the susceptibility of several different antibiotics to the chemically modifying enzymes β-lactamase and chloramphenicol acetyltransferase, enzymes used by bacteria to confer resistance to major classes of commonly used antibiotics. We also used this technique to directly monitor the effects of resistant bacteria grown in a broth containing a specific antibiotic. Because SRM is highly selective and can also identify chemical changes in a multitude of antibiotics in a single assay, SRM has the ability to detect organisms that are resistant to multiple antibiotics in a single assay. For these reasons, the use of SRM greatly reduces the time it takes to determine the susceptibility or resistance of an organism to a multitude of antibiotics by eliminating the time-consuming process found in other currently used methods.

  6. Triclosan Resistance in a Bacterial Fish Pathogen, Aeromonas salmonicida subsp. salmonicida, is Mediated by an Enoyl Reductase, FabV.

    Science.gov (United States)

    Khan, Raees; Lee, Myung Hwan; Joo, Hae-Jin; Jung, Yong-Hoon; Ahmad, Shabir; Choi, Jin-Hee; Lee, Seon-Woo

    2015-04-01

    Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX(8)K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria.

  7. Modification of β-Defensin-2 by Dicarbonyls Methylglyoxal and Glyoxal Inhibits Antibacterial and Chemotactic Function In Vitro.

    Directory of Open Access Journals (Sweden)

    Janna G Kiselar

    Full Text Available Beta-defensins (hBDs provide antimicrobial and chemotactic defense against bacterial, viral and fungal infections. Human β-defensin-2 (hBD-2 acts against gram-negative bacteria and chemoattracts immature dendritic cells, thus regulating innate and adaptive immunity. Immunosuppression due to hyperglycemia underlies chronic infection in Type 2 diabetes. Hyperglycemia also elevates production of dicarbonyls methylgloxal (MGO and glyoxal (GO.The effect of dicarbonyl on defensin peptide structure was tested by exposing recombinant hBD-2 (rhBD-2 to MGO or GO with subsequent analysis by MALDI-TOF MS and LC/MS/MS. Antimicrobial function of untreated rhBD-2 vs. rhBD-2 exposed to dicarbonyl against strains of both gram-negative and gram-positive bacteria in culture was determined by radial diffusion assay. The effect of dicarbonyl on rhBD-2 chemotactic function was determined by chemotaxis assay in CEM-SS cells.MGO or GO in vitro irreversibly adducts to the rhBD-2 peptide, and significantly reduces antimicrobial and chemotactic functions. Adducts derive from two arginine residues, Arg22 and Arg23 near the C-terminus, and the N-terminal glycine (Gly1. We show by radial diffusion testing on gram-negative E. coli and P. aeruginosa, and gram-positive S. aureus, and a chemotaxis assay for CEM-SS cells, that antimicrobial activity and chemotactic function of rhBD-2 are significantly reduced by MGO.Dicarbonyl modification of cationic antimicrobial peptides represents a potential link between hyperglycemia and the clinical manifestation of increased susceptibility to infection, protracted wound healing, and chronic inflammation in undiagnosed and uncontrolled Type 2 diabetes.

  8. Preparation of Polyester-Based Metal-Cross Linked Polymeric Composites as Novel Materials Resistant to Bacterial Adhesion and Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Mutasem O. Taha

    2011-01-01

    Full Text Available Bacterial biofilms constitute an extremely resistant form of bacterial colonization with dire health and economical implications. Towards achieving polymeric composites capable of resisting bacterial adhesion and biofilm formation, we prepared five 2,6-pyridinedicarboxylate-based polyesters employing five different diol monomers. The resulting polyesters were complexed with copper (II or silver (I. The new polymers were characterized by proton and carbon nuclear magnetic resonance spectroscopy, inherent viscosity, infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The corresponding metal complexes were characterized by differential scanning calorimery and infrared spectroscopy. The amounts of complexed copper and silver were determined by atomic absorption spectrophotometry. Finally, the resulting composites were tested for their antibacterial potential and were found to effectively resist bacterial attachment and growth.

  9. Reduction of rainbow trout spleen size by splenectomy does not alter resistance against bacterial cold water disease.

    Science.gov (United States)

    Wiens, Gregory D; Marancik, David P; Zwollo, Patty; Kaattari, Stephen L

    2015-03-01

    In lower vertebrates, the contribution of the spleen to anti-bacterial immunity is poorly understood. We have previously reported a phenotypic and genetic correlation between resistance to Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD) and spleen somatic index (spleen weight normalized to body weight, SI). Fish families with larger pre-challenge SI values were found to have greater BCWD survival (resistance) following intraperitoneal injection of a lethal dose of F. psychrophilum. Since the mammalian spleen is known to be crucial for capture and destruction of encapsulated bacteria, we tested the hypothesis that reduction of spleen size, by surgical splenectomy, should reduce the survival advantage of the larger-spleen, disease-resistant fish. Experiments were performed using two separate lines of fish that had previously been selected either based on BCWD survival (resistant and susceptible), or selected based on spleen size (high and low SI). Following 65 to 81 days post-surgical recovery, fish were challenged with F. psychrophilum and mortality monitored for a minimum of 21 days. No significant difference in the relative survival was detected between splenectomized or sham-operated groups, while SI of splenectomized fish was reduced to an average of 8-12% of control animals. A positive correlation was observed between the SI, measured at the time of splenectomy, and time-to-death post-challenge. In summary, these experiments argue that larger spleen size alone is not sufficient for greater BCWD resistance, but rather it is an indirect indicator of immunological status.

  10. Breeding of R8012, a Rice Restorer Line Resistant to Blast and Bacterial Blight Through Marker-Assisted Selection

    Institute of Scientific and Technical Information of China (English)

    ZHAN Xiao-deng; ZHOU Hai-peng; CHAI Rong-yao; ZHUANG Jie-yun; CHENG Shi-hua; CAO Li-yong

    2012-01-01

    Genetic improvement Is one of the most effective strategies to prevent rlce from blast and bacterial blight (BB)diseases,the two most prevalent diseases jeopardizing rice production.Rice hybrids with dural resistance to blast and BB are needed for sustainable production of food.An incomplete diallels design resulted in 25 crosses between five blast and five BB resistant germplasrn accesslons.Only one pair of parents,DH146 × TM487,showed polymorphism for all the markers to Identify one blast resistance gene P125 and three BB resistance genes,Xa21,xa13 and xa5,thus it was used in the marker-assisted selection (MAS).F2 individuals of DH148 × TM487 were genotyped using flanking markers of RM3330and sequence tagged site (STS) marker SAT for P125.The resistant F2 plants with P125 were used for pyramiding BB resistance genes Xa21,xa13 and xa5 identified by the markers pTA248,RM264 and RM153,respectively In subsequent generations.Finally,after selection for agronomic traits and restoration ability among 12 pyramided lines,we acquired an elite restorer line,R8012 including all four target genes (P125+Xa21+xa13+xa5).Hybrid Zhong 9A/R8012 derived from the selected line showed stronger resistance to blast and BB,and higher grain yield than the commercial checks uniformally in experimental plots,2007 state-wide yield trial and 2008 nation-wide yield trial.This study provides a paradigmatic example to show that MAS is a practically feasible tool in effectively pyramiding multiple resistance genes.The resultant restoring line and its hybrid would play an important role in securing rice production in China.

  11. Whole-Genome Sequencing of Invasion-Resistant Cells Identifies Laminin α2 as a Host Factor for Bacterial Invasion

    Science.gov (United States)

    van Wijk, Xander M.; Döhrmann, Simon; Hallström, Björn M.; Li, Shangzhong; Voldborg, Bjørn G.; Meng, Brandon X.; McKee, Karen K.; van Kuppevelt, Toin H.; Yurchenco, Peter D.; Palsson, Bernhard O.; Lewis, Nathan E.; Nizet, Victor

    2017-01-01

    ABSTRACT To understand the role of glycosaminoglycans in bacterial cellular invasion, xylosyltransferase-deficient mutants of Chinese hamster ovary (CHO) cells were created using clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated gene 9 (CRISPR-cas9) gene targeting. When these mutants were compared to the pgsA745 cell line, a CHO xylosyltransferase mutant generated previously using chemical mutagenesis, an unexpected result was obtained. Bacterial invasion of pgsA745 cells by group B Streptococcus (GBS), group A Streptococcus, and Staphylococcus aureus was markedly reduced compared to the invasion of wild-type cells, but newly generated CRISPR-cas9 mutants were only resistant to GBS. Invasion of pgsA745 cells was not restored by transfection with xylosyltransferase, suggesting that an additional mutation conferring panresistance to multiple bacteria was present in pgsA745 cells. Whole-genome sequencing and transcriptome sequencing (RNA-Seq) uncovered a deletion in the gene encoding the laminin subunit α2 (Lama2) that eliminated much of domain L4a. Silencing of the long Lama2 isoform in wild-type cells strongly reduced bacterial invasion, whereas transfection with human LAMA2 cDNA significantly enhanced invasion in pgsA745 cells. The addition of exogenous laminin-α2β1γ1/laminin-α2β2γ1 strongly increased bacterial invasion in CHO cells, as well as in human alveolar basal epithelial and human brain microvascular endothelial cells. Thus, the L4a domain in laminin α2 is important for cellular invasion by a number of bacterial pathogens. PMID:28074024

  12. Vitamin D reduces the inflammatory response by Porphyromonas gingivalis infection by modulating human β-defensin-3 in human gingival epithelium and periodontal ligament cells.

    Science.gov (United States)

    De Filippis, Anna; Fiorentino, Margherita; Guida, Luigi; Annunziata, Marco; Nastri, Livia; Rizzo, Antonietta

    2017-04-03

    Periodontitis is a multifactorial polymicrobial infection characterized by a destructive inflammatory process. Porphyromonas gingivalis, a Gram-negative black-pigmented anaerobe, is a major pathogen in the initiation and progression of periodontitis; it produces several virulence factors that stimulate human gingival epithelium (HGE) cells and human periodontal ligament (HPL) cells to produce various inflammatory mediators. A variety of substances, such as vitamin D, have growth-inhibitory effects on some bacterial pathogens and have shown chemo-preventive and anti-inflammatory activity. We used a model with HGE and HPL cells infected with P. gingivalis to determine the influence of vitamin D on P. gingivalis growth and adhesion and the immunomodulatory effect on TNF-α, IL-8, IL-12 and human-β-defensin 3 production. Our results demonstrated, firstly, the lack of any cytotoxic effect on the HGE and HPL cells when treated with vitamin D; in addition, vitamin D inhibited P. gingivalis adhesion and infectivity in HGE and HPL cells. Our study then showed that vitamin D reduced TNF-α, IL-8, IL-12 production in P. gingivalis-infected HGE and HPL cells. In contrast, a significant upregulation of the human-β-defensin 3 expression in HGE and HPL cells induced by P. gingivalis was demonstrated. Our results indicate that vitamin D specifically enhances the production of the human-β-defensin 3 antimicrobial peptide and exerts an inhibitory effect on the pro-inflammatory cytokines, thus suggesting that vitamin D may offer possible therapeutic applications for periodontitis.

  13. Ciprofloxacin Affects Host Cells by Suppressing Expression of the Endogenous Antimicrobial Peptides Cathelicidins and Beta-Defensin-3 in Colon Epithelia

    Directory of Open Access Journals (Sweden)

    Protim Sarker

    2014-07-01

    Full Text Available Antibiotics exert several effects on host cells including regulation of immune components. Antimicrobial peptides (AMPs, e.g., cathelicidins and defensins display multiple functions in innate immunity. In colonic mucosa, cathelicidins are induced by butyrate, a bacterial fermentation product. Here, we investigated the effect of antibiotics on butyrate-induced expression of cathelicidins and beta-defensins in colon epithelial cells. Real-time PCR analysis revealed that ciprofloxacin and clindamycin reduce butyrate-induced transcription of the human cathelicidin LL-37 in the colonic epithelial cell line HT-29. Suppression of LL-37 peptide/protein by ciprofloxacin was confirmed by Western blot analysis. Immunohistochemical analysis demonstrated that ciprofloxacin suppresses the rabbit cathelicidin CAP-18 in rectal epithelia of healthy and butyrate-treated Shigella-infected rabbits. Ciprofloxacin also down-regulated butyrate-induced transcription of the human beta-defensin-3 in HT-29 cells. Microarray analysis of HT-29 cells revealed upregulation by butyrate with subsequent down-regulation by ciprofloxacin of additional genes encoding immune factors. Dephosphorylation of histone H3, an epigenetic event provided a possible mechanism of the suppressive effect of ciprofloxacin. Furthermore, LL-37 peptide inhibited Clostridium difficile growth in vitro. In conclusion, ciprofloxacin and clindamycin exert immunomodulatory function by down-regulating AMPs and other immune components in colonic epithelial cells. Suppression of AMPs may contribute to the overgrowth of C. difficile, causing antibiotic-associated diarrhea.

  14. Transcriptional responses of Italian ryegrass during interaction with Xanthomonas translucens pv. graminis reveal novel candidate genes for bacterial wilt resistance

    DEFF Research Database (Denmark)

    Wichmann, Fabienne; Asp, Torben; Widmer, Franko

    2011-01-01

    selection, the partial transcriptomes of two Italian ryegrass genotypes, one resistant and one susceptible to bacterial wilt were compared at four time points after Xtg infection. A cDNA microarray developed from a perennial ryegrass (Lolium perenne) expressed sequence tag set consisting of 9,990 unique...... assisted resistance breeding....

  15. Rapid detection of bacterial resistance to antibiotics using AFM cantilevers as nanomechanical sensors.

    Science.gov (United States)

    Longo, G; Alonso-Sarduy, L; Rio, L Marques; Bizzini, A; Trampuz, A; Notz, J; Dietler, G; Kasas, S

    2013-07-01

    The widespread misuse of drugs has increased the number of multiresistant bacteria, and this means that tools that can rapidly detect and characterize bacterial response to antibiotics are much needed in the management of infections. Various techniques, such as the resazurin-reduction assays, the mycobacterial growth indicator tube or polymerase chain reaction-based methods, have been used to investigate bacterial metabolism and its response to drugs. However, many are relatively expensive or unable to distinguish between living and dead bacteria. Here we show that the fluctuations of highly sensitive atomic force microscope cantilevers can be used to detect low concentrations of bacteria, characterize their metabolism and quantitatively screen (within minutes) their response to antibiotics. We applied this methodology to Escherichia coli and Staphylococcus aureus, showing that live bacteria produced larger cantilever fluctuations than bacteria exposed to antibiotics. Our preliminary experiments suggest that the fluctuation is associated with bacterial metabolism.

  16. Bacterial cellulose produced by a new acid-resistant strain of Gluconacetobacter genus.

    Science.gov (United States)

    Castro, Cristina; Zuluaga, Robin; Álvarez, Catalina; Putaux, Jean-Luc; Caro, Gloria; Rojas, Orlando J; Mondragon, Iñaki; Gañán, Piedad

    2012-08-01

    A bacterial strain isolated from the fermentation of Colombian homemade vinegar, Gluconacetobacter medellensis, was investigated as a new source of bacterial cellulose (BC). The BC produced from substrate media consisting of various carbon sources at different pH and incubation times was quantified. Hestrin-Schramm (HS) medium modified with glucose led to the highest BC yields followed by sucrose and fructose. Interestingly, the microorganisms are highly tolerant to low pH: an optimum yield of 4.5 g/L was achieved at pH 3.5, which is generally too low for other bacterial species to function. The cellulose microfibrils produced by the new strain were characterized by scanning and transmission electron microscopy, infrared spectroscopy X-ray diffraction and elemental analysis. The morphological, structural and chemical characteristics of the cellulose produced are similar to those expected for BC.

  17. Antibacterial Activity of Four Human Beta-Defensins: HBD-19, HBD-23, HBD-27, and HBD-29

    Directory of Open Access Journals (Sweden)

    David Camerini

    2012-03-01

    Full Text Available Human β-defensins (HBD are a family of small antimicrobial peptides that play important roles in the innate and adaptive immune defenses against microbial infection. In this study, we predicted the mature sequences and assessed the antibacterial properties of synthetic HBD-19, HBD-23, HBD-27, and HBD-29 against three species of clinically relevant bacteria: Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. We also examined the cytotoxicity of each β-defensin to human cells. HBD-19 exhibited modest antibacterial effects against E. coli and S. aureus but had little effect on the growth of P. aeruginosa. HBD-23 exhibited substantial antibacterial effects against all three bacterial species and was particularly potent against the Gram-negative species, E. coli and P. aeruginosa. HBD-27 exerted modest antibacterial activity only towards S. aureus while HBD-29 had modest antibacterial activity for E. coli and P. aeruginosa. HBD-23 and HBD-27 showed little or no toxicity to human peripheral blood mononuclear cells, while HBD-19 and HBD-29 decreased cell viability by 20% at 30 μg/mL.

  18. Resistance and resilience of removal efficiency and bacterial community structure of gas biofilters exposed to repeated shock loads.

    Science.gov (United States)

    Cabrol, Léa; Malhautier, Luc; Poly, Franck; Roux, Xavier Le; Lepeuple, Anne-Sophie; Fanlo, Jean-Louis

    2012-11-01

    Since full-scale biofilters are often operated under fluctuating conditions, it is critical to understand their response to transient states. Four pilot-scale biofilters treating a composting gas mixture and undergoing repeated substrate pulses of increasing intensity were studied. A systematic approach was proposed to quantify the resistance and resilience capacity of their removal efficiency, which enabled to distinguish between recalcitrant (ammonia, DMDS, ketones) and easily degradable (esters and aldehyde) compounds. The threshold of disturbing shock intensity and the influence of disturbance history depended on the contaminant considered. The spatial and temporal distribution of the bacterial community structure in response to the perturbation regime was analysed by Denaturing Gradient Gel Electrophoresis (DGGE). Even if the substrate-pulses acted as a driving force for some community characteristics (community stratification), the structure-function relationships were trickier to evidence: the distributions of resistance and composition were only partially coupled, with contradictory results depending on the contaminant considered.

  19. Reengineering Antibiotics to Combat Bacterial Resistance: Click Chemistry [1,2,3]-Triazole Vancomycin Dimers with Potent Activity against MRSA and VRE.

    Science.gov (United States)

    Silverman, Steven M; Moses, John E; Sharpless, K Barry

    2017-01-01

    Vancomycin has long been considered a drug of last resort. Its efficiency in treating multiple drug-resistant bacterial infections, particularly methicillin-resistant Staphylococcus aureus (MRSA), has had a profound effect on the treatment of life-threatening infections. However, the emergence of resistance to vancomycin is a cause for significant worldwide concern, prompting the urgent development of new effective treatments for antibiotic resistant bacterial infections. Harnessing the benefits of multivalency and cooperativity against vancomycin-resistant strains, we report a Click Chemistry approach towards reengineered vancomycin derivatives and the synthesis of a number of dimers with increased potency against MRSA and vancomycin resistant Enterococci (VRE; VanB). These semi-synthetic dimeric ligands were linked together with great efficiency using the powerful CuAAC reaction, demonstrating high levels of selectivity and purity.

  20. Bacterial Colonization and Antibiotic Resistance in a Prospective Cohort of Newborn Infants During the First Year of Life

    Science.gov (United States)

    Stange, Kurt C.; Jacobs, Michael R.; Weiss, Judith K.; Bajaksouzian, Saralee; Bonomo, Robert A.

    2016-01-01

    Background. Infants are virtually sterile at birth and frequently use antibiotics; our objective was to (1) characterize the longitudinal colonization with bacterial pathogens and associated antibiotic resistance in a cohort of community-dwelling infants in Northeast Ohio and (2) describe longitudinal concurrent antibiotic and daycare exposures. Methods. For 35 newborns, nasopharyngeal swabs were cultured for Streptococcus pneumoniae, anterior nasal for Staphylococcus aureus, and perirectal for extended-spectrum beta-lactamase (ESBL)-producing Gram-negative enteric bacteria, at 3-month intervals for 12 months. Infant and household antibiotics and daycare exposure were assessed longitudinally. Results. Thirteen infants received perinatal or nursery antibiotics. By 3 months, at least 22 were colonized with Gram-negative bacteria; 2 with S pneumoniae (type 19A, resistant; 15C, susceptible), 5 with methicillin-susceptible S aureus. By 12 months, at least 22 of 35 infants received antibiotics, 20 had household members with antibiotics, and 12 attended daycare; 7 more had household members with daycare exposure. The ESBL-producing organisms were not identified. At least 10 infants were colonized at some time with an antibiotic-resistant organism, 3 more with pathogens displaying intermediate resistance. Pathogen colonization and resistance were intermittent and inconsistent. Conclusions. In a community-based cohort followed from birth, early antibiotic and daycare exposures are common, especially considering perinatal maternal exposures. Colonization patterns of Gram-negative bacteria, S pneumoniae, S aureus, and resistant pneumococci are strikingly dynamic. Further research can identify key areas for potential interventions to maximize clinical antibiotic outcomes while minimizing future resistance. PMID:27957505

  1. Resistance to antibiotics and inorganic ions in virulent bacterial strains from a hospital.

    Science.gov (United States)

    Vazquez, F; Fidalgo, S; Mendez, F J; Mendoza, M C

    1989-08-01

    Virulent strains of Staphylococcus aureus, S. epidermidis, Escherichia coli and Pseudomonas aeruginosa were studied for their resistance to antibiotics and inorganic ions, the correlation with their clinical use and the usefulness as an epidemioliogical tool. Multiresistance was common, the antibiotypes were similar to those previously reported, but characteristic resistotypes endemic of our county were found. A correlation between resistance and metal ion consumption was not detected. Staphylococci strains were susceptible to vancomycin, cephalothin and mercury chloride; S. epidermidis showed higher rates of resistance to antibiotics and lower to cadmium chloride and potassium iodine than S. aureus. E. coli strains were susceptible to new beta-lactamans; resistance to cephalothin, gentamicin, tobramycin and amikacin was less than 10%. P, aeruginosa was the species with the most multiresistance and antibiotype diversity, only ceftazidime, amikacin and imipenem had a resistance rate less than 11%. In both E. coli and P. aeruginosa resistance to all tested metals (except silver nitrate) was found although with different percentages.

  2. C/EBPβ Promotes Immunity to Oral Candidiasis through Regulation of β-Defensins.

    Science.gov (United States)

    Simpson-Abelson, Michelle R; Childs, Erin E; Ferreira, M Carolina; Bishu, Shrinivas; Conti, Heather R; Gaffen, Sarah L

    2015-01-01

    Humans or mice subjected to immunosuppression, such as corticosteroids or anti-cytokine biologic therapies, are susceptible to mucosal infections by the commensal fungus Candida albicans. Recently it has become evident that the Th17/IL-17 axis is essential for immunity to candidiasis, but the downstream events that control immunity to this fungus are poorly understood. The CCAAT/Enhancer Binding Protein-β (C/EBPβ) transcription factor is important for signaling by multiple inflammatory stimuli, including IL-17. C/EBPβ is regulated in a variety of ways by IL-17, and controls several downstream IL-17 target genes. However, the role of C/EBPβ in vivo is poorly understood, in part because C/EBPβ-deficient mice are challenging to breed and work with. In this study, we sought to understand the role of C/EBPβ in the context of an IL-17-dependent immune response, using C. albicans infection as a model system. Confirming prior findings, we found that C/EBPβ is required for immunity to systemic candidiasis. In contrast, C/EBPβ(-/-) mice were resistant to oropharyngeal candidiasis (OPC), in a manner indistinguishable from immunocompetent WT mice. However, C/EBPβ(-/-) mice experienced more severe OPC than WT mice in the context of cortisone-induced immunosuppression. Expression of the antimicrobial peptide β-defensin (BD)-3 correlated strongly with susceptibility in C/EBPβ(-/-) mice, but no other IL-17-dependent genes were associated with susceptibility. Therefore, C/EBPβ contributes to immunity to mucosal candidiasis during cortisone immunosuppression in a manner linked to β-defensin 3 expression, but is apparently dispensable for the IL-17-dependent response.

  3. Bottlenecks in the Transferability of Antibiotic Resistance from Natural Ecosystems to Human Bacterial Pathogens

    OpenAIRE

    Martínez, José L.

    2012-01-01

    It is generally accepted that resistance genes acquired by human pathogens through horizontal gene transfer originated in environmental, non-pathogenic bacteria. As a consequence, there is increasing concern on the roles that natural, non-clinical ecosystems, may play in the evolution of resistance. Recent studies have shown that the variability of determinants that can provide antibiotic resistance on their expression in a heterologous host is much larger than what is actually found in human...

  4. Evaluation of beta defensin 2 production by chicken heterophils using direct MALDI mass spectrometry

    Science.gov (United States)

    Beta defensins (BD) are cysteine rich, cationic antimicrobial peptides (AMP) produced mainly by epithelial and myeloid cells such as neutrophils. In birds, the equivalent of neutrophils, heterophils produce avian beta defensins (AvBD) of which AvBD2 is the major isoform. Heterophils recognize patho...

  5. Alpha-defensin DEFA1A3 gene copy number elevation in Danish Crohn's disease patients

    DEFF Research Database (Denmark)

    Jespersgaard, Cathrine; Fode, Peder; Dybdahl, Marianne

    2011-01-01

    BACKGROUND AND PURPOSE OF STUDY: Extensive copy number variation is observed for the DEFA1A3 gene encoding alpha-defensins 1-3. The objective of this study was to determine the involvement of alpha-defensins in colonic tissue from Crohn's disease (CD) patients and the possible genetic association...

  6. Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

    Directory of Open Access Journals (Sweden)

    Saswati Saha

    2016-04-01

    Full Text Available Abstract Integration of biology with nanotechnology is now becoming attention-grabbing area of research. The antimicrobial potency of silver has been eminent from antiquity. Due to the recent desire for the enhancement of antibacterial efficacy of silver, various synthesis methods of silver in their nano dimensions are being practiced using a range of capping material. The present work highlights a facile biomimetic approach for production of silver nanoparticle being capped and stabilized by putrescine, possessing a diameter of 10–25 ± 1.5 nm. The synthesized nanoparticles have been analyzed spectrally and analytically. Morphological studies are carried out by high-resolution transmission electron microscopy and crystallinity by selected area electron diffraction patterns. Moreover, the elemental composition of the capped nanoparticles was confirmed by energy-dispersive X-ray spectroscopy analysis. A comparative study (zone of inhibition and minimum inhibitory concentration regarding the interactions and antibacterial potentiality of the capped silver nanoparticles with respect to the bare ones reveal the efficiency of the capped one over the bare one. The bacterial kinetic study was executed to monitor the interference of nanoparticles with bacterial growth rate. The results also highlight the efficacy of putrescine-capped silver nanoparticles as effective growth inhibitors against multi-drug resistant human pathogenic bacterial strains, which may, thus, potentially be applicable as an effective antibacterial control system to fight diseases.

  7. Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

    Science.gov (United States)

    Saha, Saswati; Gupta, Bhaskar; Gupta, Kamala; Chaudhuri, Mahua Ghosh

    2016-04-01

    Integration of biology with nanotechnology is now becoming attention-grabbing area of research. The antimicrobial potency of silver has been eminent from antiquity. Due to the recent desire for the enhancement of antibacterial efficacy of silver, various synthesis methods of silver in their nano dimensions are being practiced using a range of capping material. The present work highlights a facile biomimetic approach for production of silver nanoparticle being capped and stabilized by putrescine, possessing a diameter of 10-25 ± 1.5 nm. The synthesized nanoparticles have been analyzed spectrally and analytically. Morphological studies are carried out by high-resolution transmission electron microscopy and crystallinity by selected area electron diffraction patterns. Moreover, the elemental composition of the capped nanoparticles was confirmed by energy-dispersive X-ray spectroscopy analysis. A comparative study (zone of inhibition and minimum inhibitory concentration) regarding the interactions and antibacterial potentiality of the capped silver nanoparticles with respect to the bare ones reveal the efficiency of the capped one over the bare one. The bacterial kinetic study was executed to monitor the interference of nanoparticles with bacterial growth rate. The results also highlight the efficacy of putrescine-capped silver nanoparticles as effective growth inhibitors against multi-drug resistant human pathogenic bacterial strains, which may, thus, potentially be applicable as an effective antibacterial control system to fight diseases.

  8. Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

    Science.gov (United States)

    Saha, Saswati; Gupta, Bhaskar; Gupta, Kamala; Chaudhuri, Mahua Ghosh

    2016-11-01

    Integration of biology with nanotechnology is now becoming attention-grabbing area of research. The antimicrobial potency of silver has been eminent from antiquity. Due to the recent desire for the enhancement of antibacterial efficacy of silver, various synthesis methods of silver in their nano dimensions are being practiced using a range of capping material. The present work highlights a facile biomimetic approach for production of silver nanoparticle being capped and stabilized by putrescine, possessing a diameter of 10-25 ± 1.5 nm. The synthesized nanoparticles have been analyzed spectrally and analytically. Morphological studies are carried out by high-resolution transmission electron microscopy and crystallinity by selected area electron diffraction patterns. Moreover, the elemental composition of the capped nanoparticles was confirmed by energy-dispersive X-ray spectroscopy analysis. A comparative study (zone of inhibition and minimum inhibitory concentration) regarding the interactions and antibacterial potentiality of the capped silver nanoparticles with respect to the bare ones reveal the efficiency of the capped one over the bare one. The bacterial kinetic study was executed to monitor the interference of nanoparticles with bacterial growth rate. The results also highlight the efficacy of putrescine-capped silver nanoparticles as effective growth inhibitors against multi-drug resistant human pathogenic bacterial strains, which may, thus, potentially be applicable as an effective antibacterial control system to fight diseases.

  9. Responses of plasmid-mediated quinolone resistance genes and bacterial taxa to (fluoro)quinolones-containing manure in arable soil.

    Science.gov (United States)

    Xiong, Wenguang; Sun, Yongxue; Ding, Xueyao; Zhang, Yiming; Zhong, Xiaoxia; Liang, Wenfei; Zeng, Zhenling

    2015-01-01

    The aim of the present study was to investigate the fate of plasmid-mediated quinolone resistance (PMQR) genes and the disturbance of soil bacterial communities posed by (fluoro)quinolones (FQNs)-containing manure in arable soil. Representative FQNs (enrofloxacin (ENR), ciprofloxacin (CIP) and norfloxacin (NOR)), PMQR genes (qepA, oqxA, oqxB, aac(6')-Ib-cr and qnrS) and bacterial communities in untreated soil, +manure and +manure+FQNs groups were analyzed using culture independent methods. The significantly higher abundance of oqxA, oqxB and aac(6')-Ib-cr, and significantly higher abundance of qnrS in +manure group than those in untreated soil disappeared at day 30 and day 60, respectively. All PMQR genes (oqxA, oqxB, aac(6')-Ib-cr and qnrS) dissipated 1.5-1.7 times faster in +manure group than those in +manure+FQNs group. The disturbance of soil bacterial communities posed by FQNs-containing manure was also found. The results indicated that significant effects of PMQR genes (oqxA, oqxB, aac(6')-Ib and qnrS) on arable soils introduced by manure disappeared 2 month after manure application. FQNs introduced by manure slowed down the dissipation of PMQR genes. The presence of high FQNs provided a selective advantage for species affiliated to the phylum including Acidobacteria, Verrucomicrobia and Planctomycetes while suppressing Proteobacteria and Actinobacteria.

  10. The role of silicon in enhancing resistance to bacterial blight of hydroponic- and soil-cultured rice.

    Science.gov (United States)

    Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao

    2016-04-19

    Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the -Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from -Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the -Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the -Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in -Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively.

  11. The role of silicon in enhancing resistance to bacterial blight of hydroponic- and soil-cultured rice

    Science.gov (United States)

    Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao

    2016-01-01

    Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the −Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from −Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the −Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the −Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in −Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively. PMID:27091552

  12. Vitamin D Signaling through Induction of Paneth Cell Defensins Maintains Gut Microbiota and Improves Metabolic Disorders and Hepatic Steatosis in Animal Models.

    Science.gov (United States)

    Su, Danmei; Nie, Yuanyang; Zhu, Airu; Chen, Zishuo; Wu, Pengfei; Zhang, Li; Luo, Mei; Sun, Qun; Cai, Linbi; Lai, Yuchen; Xiao, Zhixiong; Duan, Zhongping; Zheng, Sujun; Wu, Guihui; Hu, Richard; Tsukamoto, Hidekazu; Lugea, Aurelia; Liu, Zhenqui; Pandol, Stephen J; Han, Yuan-Ping

    2016-01-01

    Metabolic syndrome (MetS), characterized as obesity, insulin resistance, and non-alcoholic fatty liver diseases (NAFLD), is associated with vitamin D insufficiency/deficiency in epidemiological studies, while the underlying mechanism is poorly addressed. On the other hand, disorder of gut microbiota, namely dysbiosis, is known to cause MetS and NAFLD. It is also known that systemic inflammation blocks insulin signaling pathways, leading to insulin resistance and glucose intolerance, which are the driving force for hepatic steatosis. Vitamin D receptor (VDR) is highly expressed in the ileum of the small intestine, which prompted us to test a hypothesis that vitamin D signaling may determine the enterotype of gut microbiota through regulating the intestinal interface. Here, we demonstrate that high-fat-diet feeding (HFD) is necessary but not sufficient, while additional vitamin D deficiency (VDD) as a second hit is needed, to induce robust insulin resistance and fatty liver. Under the two hits (HFD+VDD), the Paneth cell-specific alpha-defensins including α-defensin 5 (DEFA5), MMP7 which activates the pro-defensins, as well as tight junction genes, and MUC2 are all suppressed in the ileum, resulting in mucosal collapse, increased gut permeability, dysbiosis, endotoxemia, systemic inflammation which underlie insulin resistance and hepatic steatosis. Moreover, under the vitamin D deficient high fat feeding (HFD+VDD), Helicobacter hepaticus, a known murine hepatic-pathogen, is substantially amplified in the ileum, while Akkermansia muciniphila, a beneficial symbiotic, is diminished. Likewise, the VD receptor (VDR) knockout mice exhibit similar phenotypes, showing down regulation of alpha-defensins and MMP7 in the ileum, increased Helicobacter hepaticus and suppressed Akkermansia muciniphila. Remarkably, oral administration of DEFA5 restored eubiosys, showing suppression of Helicobacter hepaticus and increase of Akkermansia muciniphila in association with resolving

  13. Vitamin D Signaling Through Induction of Paneth Cell Defensins Maintains Gut Microbiota and Improves Metabolic Disorders and Hepatic Steatosis in Animal Models

    Directory of Open Access Journals (Sweden)

    Danmei Su

    2016-11-01

    Full Text Available Metabolic syndrome (MetS, characterized as obesity, insulin resistance, and non-alcoholic fatty liver diseases (NAFLD,is associated with vitamin D insufficiency/deficiency in epidemiological studies, while the underlying mechanism is poorly addressed. On the other hand, disorder of gut microbiota, namely dysbiosis, is known to cause MetS and NAFLD. It is also known that systemic inflammation blocks insulin signaling pathways, leading to insulin resistance and glucose intolerance, which are the driving force for hepatic steatosis. Vitamin D receptor (VDR is highly expressed in the ileum of the small intestine,which prompted us to test a hypothesis that vitamin D signaling may determine the enterotype of gut microbiota through regulating the intestinal interface. Here, we demonstrate that high-fat-diet feeding (HFD is necessary but not sufficient, while additional vitamin D deficiency (VDD as a second hit is needed, to induce robust insulin resistance and fatty liver. Under the two hits (HFD+VDD, the Paneth cell-specific alpha-defensins including α-defensin 5 (DEFA5, MMP7 which activates the pro-defensins, as well as tight junction genes, and MUC2 are all suppressed in the ileum, resulting in mucosal collapse, increased gut permeability, dysbiosis, endotoxemia, systemic inflammation which underlie insulin resistance and hepatic steatosis. Moreover, under the vitamin D deficient high fat feeding (HFD+VDD, Helicobacter hepaticus, a known murine hepatic-pathogen, is substantially amplified in the ileum, while Akkermansia muciniphila, a beneficial symbiotic, is diminished. Likewise, the VD receptor (VDR knockout mice exhibit similar phenotypes, showing down regulation of alpha-defensins and MMP7 in the ileum, increased Helicobacter hepaticus and suppressed Akkermansia muciniphila. Remarkably, oral administration of DEFA5 restored eubiosys, showing suppression of Helicobacter hepaticus and increase of Akkermansia muciniphila in association with

  14. Functional studies of cochleate assemblies of an oligo-acyl-lysyl with lipid mixtures for combating bacterial multidrug resistance.

    Science.gov (United States)

    Sarig, Hadar; Ohana, Dafna; Epand, Raquel F; Mor, Amram; Epand, Richard M

    2011-10-01

    The cationic antimicrobial oligo-acyl-lysyls (OAKs) interact with lipid mixtures mimicking the composition of bacterial cytoplasmic membranes. We have reported the ability of one such OAK, C(12)K-7α(8), to cluster anionic lipids and to promote a structural change with lipid bilayers to form rolled cylindrical structures or cochleates, without requiring divalent cations for their assembly. These assemblies can be exploited for drug delivery, permitting their synergistic use with antibiotics in systemic therapy to increase efficacy and reduce toxicity. Our previous studies of the biophysical properties of these systems led us to select mixtures with the goal of optimizing their potential for enhancing effectiveness in combating bacterial multidrug resistance. Here, we further investigate the properties of such mixtures that result in enhanced in vivo activity. The role of erythromycin in the assembly of cochleates with OAK in the gel and the liquid crystalline states were assessed, as well as the encapsulation efficiency of the systems chosen. In addition, we found that erythromycin did not undermine the ability of OAKs to induce fusion of vesicles, fusion being an essential component of cochleate formation. The in vivo activity of the new assemblies tested resulted in higher survival rates of animals infected with multidrug resistant bacteria.

  15. BACTERIAL EPIDEMIOLOGY AND ANTIMICROBIAL RESISTANCE IN THE SURGERY WARDS OF A LARGE TEACHING HOSPITAL IN SOUTHERN ITALY

    Directory of Open Access Journals (Sweden)

    Silvano Esposito

    2015-05-01

    Full Text Available Objectives: Surgical infections represent an increasingly important problem for the National Health System. In this study we retrospectively evaluated the bacterial epidemiology and antimicrobial susceptibility of the microorganisms concerned as well as the utilization of antibiotics in the General and Emergency Surgery wards of a large teaching hospital in southern Italy in the period 2011-2013. Methods: Data concerning bacterial isolates and antimicrobial susceptibility were retrieved from the Vitek II database. The pharmacy provided data about the consumption of antibiotics in the above reported wards. Chi-square or Fisher’s exact test were used to analyze categorical variables. Results: In all, 94 Gram-negative were isolated in 2011, 77 in 2012, and 125 in 2013, Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa always being the most frequently isolated microorganisms. In the same years, there were respectively 105, 93, and 165 Gram-positive isolated, Enterococcus faecalis, Staphylococcus epidermidis and Staphylococcus aureus being the most commonly found. No significant variation in the antibiotic susceptibility pattern was observed, either among Gram-negative or among Gram-positive pathogens; carbapenems (especially meropenem consumption remained stable over time. Conclusions: Our results show no significant increase in antimicrobial resistance over the period in question, and a higher rate of both MRSA isolates and resistance to carbapenems in A. baumannii compared with other European data.

  16. "ETIOLOGY AND ANTIBACTERIAL RESISTANCE OF BACTERIAL URINARY TRACT INFECTIONS IN CHILDREN’S MEDICAL CENTER, TEHRAN, IRAN"

    Directory of Open Access Journals (Sweden)

    M. Haghi-Ashteiani

    2007-06-01

    Full Text Available Urinary tract infection (UTI is a common bacterial illness in children. Knowledge of the antimicrobial resistance patterns of common uropathogens in children according to local epidemiology is essential for providing clinically appropriate, cost effective therapy for UTI. The aim of this study was to determine the distribution of urinary tract infections in a referral hospital, Children’s Medical Center, and determination of in vitro susceptibility of these organisms to antimicrobial agents. Of the 1231 bacterial isolates the most frequent isolates were Escherichia coli (38.66%, Klebsiella spp. (22.25%, Coagulase-negative staphylococci (10.1%, Pseudomonas spp. (8.7%, enterococci (8.28%, Enterobacter spp. (4.1%, staphylococcus aureus (3.24%, and proteus mirabilis (2.9%. Among Enterobacteriaceae, 79.80% of E. coli were amikacin-sensitive. Of Gram-positive cocci, 66.66% of staphylococcus aureus were vancomycin-sensitive. Our data show the original distribution of uropathogens from UTIs in children referred to Children’s Medical Center in Tehran and the emergence of multidrug resistant strains.

  17. EDS1 mediates pathogen resistance and virulence function of a bacterial effector in soybean

    Science.gov (United States)

    Enhanced disease susceptibility 1 (EDS1) and phytoalexin deficient 4 (PAD4) are well known regulators of both basal and resistance (R) protein-mediated plant defense. We identified two EDS1- (GmEDS1a/b) and one PAD4-like (GmPAD4) protein that are required for resistance signaling in soybean. Consist...

  18. Mathematical modeling on bacterial resistance to multiple antibiotics caused by spontaneous mutations.

    Science.gov (United States)

    Ibargüen-Mondragón, Eduardo; Mosquera, Saulo; Cerón, Miller; Burbano-Rosero, Edith Mariela; Hidalgo-Bonilla, Sandra P; Esteva, Lourdes; Romero-Leitón, Jhoana P

    2014-03-01

    We formulate a mathematical model that describes the population dynamics of bacteria exposed to multiple antibiotics simultaneously, assuming that acquisition of resistance is through mutations due to antibiotic exposure. Qualitative analysis reveals the existence of a free-bacteria equilibrium, resistant-bacteria equilibrium and an endemic equilibrium where both bacteria coexist.

  19. Hidden Selection of Bacterial Resistance to Fluoroquinolones In Vivo: The Case of Legionella pneumophila and Humans

    Directory of Open Access Journals (Sweden)

    Lubana Shadoud

    2015-09-01

    Interpretation: In vivo selection of antibiotic resistances in L. pneumophila may be associated with treatment failures and poor prognosis. This hidden resistance must be carefully considered in the therapeutic management of legionellosis patients and in the control of the gradual loss of effectiveness of antibiotics.

  20. Bacterial urinary tract infection in renal transplant recipients and their antibiotic resistance pattern: A four-year study.

    Directory of Open Access Journals (Sweden)

    Azar Dokht Khosravi

    2014-04-01

    Full Text Available Urinary tract infections (UTIs are the most common infections in renal transplant recipients and are considered a potential cause of bacteremia, sepsis, and affects graft outcomes. The aim of the present study was to determine the incidence of UTI among renal transplant recipients and investigation of antimicrobial susceptibility pattern of causative agents.In total, 1165 patients from March 2009 to December 2012, in transplant center of Golestan Hospital, Ahvaz, Iran, were investigated. Qualitative urine cultures were performed for all cases, causative microorganisms were identified and colony count was performed according to the standard protocol. Antibiotic susceptibility testing was then performed to determine the susceptibility pattern of recovered bacteria from confirmed UTIs.UTI was diagnosed in 391 patients(33.56%. Gram-negative bacteria were the most prevalent isolated microorganisms with E. coli (43.53%, followed by Enterobacter spp. (35.37% as the major organisms. Among Gram positives, Coagulase-negative Staphylococci was isolated from 6.8% of cases. The rate of resistance to all tested antibiotics was highest in Enterobacter spp., however the most common resistance were seen against cefixime, cephalotin, and cotrimoxazole in all tested gram negatives.the rate of UTIs among renal transplant recipients was noticeable in this study with high antibiotic resistance. Multi-resistant bacterial infections are potentially life-threatening emerging problem in renal transplantation. Prophylactic measures must be applied to patients at greater risk.

  1. Over-expression of rice leucine-rich repeat protein results in activation of defense response, thereby enhancing resistance to bacterial soft rot in Chinese cabbage.

    Science.gov (United States)

    Park, Young Ho; Choi, Changhyun; Park, Eun Mi; Kim, Hyo Sun; Park, Hong Jae; Bae, Shin Cheol; Ahn, Ilpyung; Kim, Min Gab; Park, Sang Ryeol; Hwang, Duk-Ju

    2012-10-01

    Pectobacterium carotovorum subsp. carotovorum causes soft rot disease in various plants, including Chinese cabbage. The simple extracellular leucine-rich repeat (eLRR) domain proteins have been implicated in disease resistance. Rice leucine-rich repeat protein (OsLRP), a rice simple eLRR domain protein, is induced by pathogens, phytohormones, and salt. To see whether OsLRP enhances disease resistance to bacterial soft rot, OsLRP was introduced into Chinese cabbage by Agrobacterium-mediated transformation. Two independent transgenic lines over-expressing OsLRP were generated and further analyzed. Transgenic lines over-expressing OsLRP showed enhanced disease resistance to bacterial soft rot compared to non-transgenic control. Bacterial growth was retarded in transgenic lines over-expressing OsLRP compared to non-transgenic controls. We propose that OsLRP confers enhanced resistance to bacterial soft rot. Monitoring expression of defense-associated genes in transgenic lines over-expressing OsLRP, two different glucanases and Brassica rapa polygalacturonase inhibiting protein 2, PDF1 were constitutively activated in transgenic lines compared to non-transgenic control. Taken together, heterologous expression of OsLRP results in the activation of defense response and enhanced resistance to bacterial soft rot.

  2. Bacterial antibiotic resistance levels in Danish farmland as a result of treatment with pig manure slurry

    DEFF Research Database (Denmark)

    Sengeløv, Gitte; Agersø, Yvonne; Halling-Sørensen, B.

    2003-01-01

    Resistance to tetracycline, macrolides and streptomycin was measured for a period of 8 months in soil bacteria obtained from farmland treated with pig manure slurry. This was done by spread plating bacteria on selective media (Luria Bertani (LB) medium supplemented with antibiotics). To account...... for seasonal variations in numbers of soil bacteria, ratios of resistant bacteria divided by total count on nonselective plates were calculated. Soil samples were collected from four different farms and from a control soil on a fifth farm. The control soil was not amended with animal manure. The occurrence...... of tetracycline-resistant bacteria was elevated after spread of pig manure slurry but declined throughout the sampling period to a level corresponding to the control soil. Higher load of pig manure slurry yielded higher occurrence of tetracycline resistance after spreading; however, the tetracycline resistance...

  3. Increasing Ciprofloxacin Resistance Among Prevalent Urinary Tract Bacterial Isolates in Gaza Strip, Palestine

    Directory of Open Access Journals (Sweden)

    Zakaria El Astal

    2005-01-01

    Full Text Available This article presents the incidence of ciprofloxacin resistance among 480 clinical isolates obtained from patients with urinary tract infection (UTI during January to June 2004 in Gaza Strip, Palestine. The resistance rates observed were 15.0% to ciprofloxacin, 82.5% to amoxycillin, 64.4% to cotrimoxazole, 63.1% to doxycycline, 32.5% to cephalexin, 31.9% to nalidixic acid, and 10.0% to amikacin. High resistance to ciprofloxacin was detected among Acinetobacter haemolyticus (28.6%, Staphylococcus saprophyticus (25.0%,Pseudomonas aeruginosa (20.0%, Klebsiella pneumonia (17.6%, and Escherichia coli (12.0%. Minimal inhibitory concentration (MIC of ciprofloxacin evenly ranged from 4 to 32 μg/mL with a mean of 25.0 μg/mL. This study indicates emerging ciprofloxacin resistance among urinary tract infection isolates. Increasing resistance against ciprofloxacin demands coordinated monitoring of its activity and rational use of the antibiotics.

  4. Identification, cloning and functional characterization of novel beta-defensins in the rat (Rattus norvegicus

    Directory of Open Access Journals (Sweden)

    French Frank S

    2006-02-01

    Full Text Available Abstract Background beta-defensins are small cationic peptides that exhibit broad spectrum antimicrobial properties. The majority of beta-defensins identified in humans are predominantly expressed in the male reproductive tract and have roles in non-immunological processes such as sperm maturation and capacitation. Characterization of novel defensins in the male reproductive tract can lead to increased understanding of their dual roles in immunity and sperm maturation. Methods In silico rat genomic analyses were used to identify novel beta-defensins related to human defensins 118–123. RNAs isolated from male reproductive tract tissues of rat were reverse transcribed and PCR amplified using gene specific primers for defensins. PCR products were sequenced to confirm their identity. RT-PCR analysis was performed to analyze the tissue distribution, developmental expression and androgen regulation of these defensins. Recombinant defensins were tested against E. coli in a colony forming unit assay to analyze their antimicrobial activities. Results Novel beta-defensins, Defb21, Defb24, Defb27, Defb30 and Defb36 were identified in the rat male reproductive tract. Defb30 and Defb36 were the most restricted in expression, whereas the others were expressed in a variety of tissues including the female reproductive tract. Early onset of defensin expression was observed in the epididymides of 10–60 day old rats. Defb21-Defb36 expression in castrated rats was down regulated and maintained at normal levels in testosterone supplemented animals. DEFB24 and DEFB30 proteins showed potent dose and time dependent antibacterial activity. Conclusion Rat Defb21, Defb24, Defb27, Defb30 and Defb36 are abundantly expressed in the male reproductive tract where they most likely protect against microbial invasion. They are developmentally regulated and androgen is required for full expression in the adult epididymis.

  5. Defensin expression in chronic pouchitis in patients with ulcerative colitis or familial adenomatous polyposis coli

    Institute of Scientific and Technical Information of China (English)

    Karlheinz Kiehne; Gabriele Brunke; Franziska Wegner; Tomas Banasiewicz; Ulrich R F(o)lsch; Karl-Heinz Herzig

    2006-01-01

    AIM:Pouchitis develops in ileoanal pouches in up to 50% of patients with ulcerative colitis during the first 10years after pouch surgery while being rare in patients after proctocolectomy for familial adenomatous polyposis coii (FAP) syndrome. Defensins are major components of the innate immune system and play a significant role in gastrointestinal microbial homeostasis. Pouch defensin and cytokine expression were correlated with states of pouch inflammation to study their role in pouchitis.METHODS:Patients with ulcerative colitis and FAP syndrome were stratified into groups with pouches after surgery, pouches without or with pouchitis. Biopsies from terminal ileum from a healthy intestine or from normal terminal ileum of patients with ulcerative colitis served as controls, mRNA from pouches and controls was analysed for defensin and cytokine expression.RESULTS: Expression of defensins was increased in all pouches immediately after surgery, compared to ileum of controls. Initially, pouches in ulcerative colitis revealed higher defensin expression than FAP pouches. Defensin expression declined in both patient groups and increased again slightly in pouchitis in patients with ulcerative colitis. FAP pouches without pouchitis had strong expression of β-defensin hBD-1, while all other defensins remained at low levels. Cytokine expression in ulcerative colitis pouches was high, while FAP pouches showed moderately elevated cytokines only after surgery.CONCLUSION: Development of pouchitis correlates with decreased defensin expression in ulcerative colitis in addition to high expression of cytokines. The low incidence of pouchitis in FAP pouches correlates with increased expression of hBD-1 β- defensin in association with low cytokine levels.

  6. Synergistic and additive effect of oregano essential oil and biological silver nanoparticles against multidrug-resistant bacterial strains

    Directory of Open Access Journals (Sweden)

    Sara eScandorieiro

    2016-05-01

    Full Text Available Bacterial resistance to conventional antibiotics has become a clinical and public health problem, making therapeutic decisions more challenging. Plant compounds and nanodrugs have been proposed as potential antimicrobial alternatives. Studies have shown that oregano (Origanum vulgare essential oil (OEO and silver nanoparticles have potent antibacterial activity, also against multidrug-resistant strains; however, the strong organoleptic characteristics of OEO and the development of resistance to these metal nanoparticles can limit their use. This study evaluated the antibacterial effect of a two-drug combination of biologically synthesized silver nanoparticles (bio-AgNP, produced by Fusarium oxysporum, and OEO against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. OEO and bio-AgNP showed bactericidal effects against all seventeen strains tested, with minimal inhibitory concentrations (MIC ranging from 0.298 to 1.193 mg/mL and 62.5 to 250 µM, respectively. Time-kill curves indicated that OEO acted rapidly (within 10 min, while the metallic nanoparticles took 4 h to kill Gram-negative bacteria and 24 h to kill Gram-positive bacteria. The combination of the two compounds resulted in a synergistic or additive effect, reducing their MIC values and reducing the time of action compared to bio-AgNP used alone, i.e., 20 min for Gram-negative bacteria and 7 h for Gram-positive bacteria. Scanning electron microscopy (SEM revealed similar morphological alterations in Staphylococcus aureus (non-methicillin-resistant S. aureus, non-MRSA cells exposed to three different treatments (OEO, bio-AgNP and combination of the two, which appeared cell surface blebbing. Individual and combined treatments showed reduction in cell density and decrease in exopolysaccharide matrix compared to untreated bacterial cells. It indicated that this composition have an antimicrobial activity against S. aureus by disrupting cells. Both compounds

  7. Gram-positive bacterial resistant strains of interest in animal and public health

    Directory of Open Access Journals (Sweden)

    Ricardo Antonio Pilegi Sfaciotte

    2015-08-01

    Full Text Available Among multiresistant Gram-positive microorganisms, stands out methicillin-resistant Staphylococcus (MRS, an opportunistic pathogen associated with hospital acquired and community infections reported in medicine and large increase in reports of veterinary medicine. In veterinary medicine, numerous reports regarding several species of animals have been described. MRS is intrinsically resistant to all ?-lactam drugs. In veterinary medicine, numerous reports regarding several species of animals have been described, but Staphylococcus aureus with intermediate resistance and resistant to vancomycin (VISA/VRSA has not yet been reported in veterinary medicine, still need further study. Staphylococcus spp. are also related to antimicrobial resistance of macrolides, lincosamides, and streptogramin B (MLSB group, that has the same mechanism of action, although the drugs belong to different classes. In veterinary medicine, clindamycin (lincosamide class is widely used for skin infections, wounds, bone infections, pneumonia, infections of the oral cavity, and infections caused by anaerobic bacteria, besides being used for treatments of MRS infections. Enterococcus is another resistant Gram-positive microorganism, from which vancomycin-resistant enterococci (VREs are the most important strains. There are several reports of VREs in veterinary medicine due the use of a similar antimicrobial (avoparcin in livestock; therefore this group of microorganisms has now acquired great prominence since vancomycin is considered as the last resort for the treatment of MRS and Enterococcus associated with nosocomial infections in humans. The biggest problem these microorganisms and their resistance mechanisms cause is related to its huge impact on public health due to the increasing close contact between animals and humans. The objective of this review was to identify the main Gram-positive microorganisms associated with animals, describing their mechanisms of action that

  8. Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance.

    Science.gov (United States)

    Abhilash Kumar, V; Balachiranjeevi, C H; Bhaskar Naik, S; Rambabu, R; Rekha, G; Harika, G; Hajira, S K; Pranathi, K; Anila, M; Kousik, M; Vijay Kumar, S; Yugander, A; Aruna, J; Dilip Kumar, T; Vijaya Sudhakara Rao, K; Hari Prasad, A S; Madhav, M S; Laha, G S; Balachandran, S M; Prasad, M S; Viraktamath, B C; Ravindra Babu, V; Sundaram, R M

    2016-01-01

    RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the

  9. Effect of Seed Treatment by Cold Plasma on the Resistance of Tomato to Ralstonia solanacearum (Bacterial Wilt)

    Science.gov (United States)

    Jiang, Jiafeng; Lu, Yufang; Li, Jiangang; Li, Ling; He, Xin; Shao, Hanliang; Dong, Yuanhua

    2014-01-01

    This study investigated the effect of cold plasma seed treatment on tomato bacterial wilt, caused by Ralstonia solanacearum (R. solanacearum), and the regulation of resistance mechanisms. The effect of cold plasma of 80W on seed germination, plant growth, nutrient uptake, disease severity, hydrogen peroxide (H2O2) concentration and activities of peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.2) and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were examined in tomato plants. Plasma treatment increased tomato resistance to R. solanacearum with an efficacy of 25.0%. Plasma treatment significantly increased both germination and plant growth in comparison with the control treatment, and plasma-treated plants absorbed more calcium and boron than the controls. In addition, H2O2 levels in treated plants rose faster and reached a higher peak, at 2.579 µM gFW−1, 140% greater than that of the control. Activities of POD (421.3 U gFW−1), PPO (508.8 U gFW−1) and PAL (707.3 U gFW−1) were also greater in the treated plants than in the controls (103.0 U gFW−1, 166.0 U gFW−1 and 309.4 U gFW−1, respectively). These results suggest that plasma treatment affects the regulation of plant growth, H2O2 concentration, and POD, PPO and PAL activity in tomato, resulting in an improved resistance to R. solanacearum. Consequently, cold plasma seed treatment has the potential to control tomato bacterial wilt caused by R. solanacearum. PMID:24840508

  10. Ecological effects of selective decontamination on resistant gram-negative bacterial colonization.

    NARCIS (Netherlands)

    Oostdijk, E.A.; Smet, A.M. de; Blok, H.E.; Thieme Groen, E.S.; Asselt, G.J. van; Benus, R.F.; Bernards, S.A.; Frenay, I.H.; Jansz, A.R.; Jongh, B.M. de; Kaan, J.A.; Leverstein-van Hall, M.A.; Mascini, E.M.; Pauw, W.; Sturm, P.D.J.; Thijsen, S.F.; Kluytmans, J.A.; Bonten, M.J.

    2010-01-01

    RATIONALE: Selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) eradicate gram-negative bacteria (GNB) from the intestinal and respiratory tract in intensive care unit (ICU) patients, but their effect on antibiotic resistance remains controversial. OBJECT

  11. Ecological Effects of Selective Decontamination on Resistant Gram-negative Bacterial Colonization

    NARCIS (Netherlands)

    Oostdijk, Evelien A. N.; de Smet, Anne Marie G. A.; Blok, Hetty E. M.; Groen, Emily S. Thieme; van Asselt, Gerard J.; Benus, Robin F. J.; Bernards, Sandra A. T.; Frenay, Ine H. M. E.; Jansz, Arjan R.; de Jongh, Bartelt M.; Kaan, Jan A.; Leverstein-van Hall, Maurine A.; Mascini, Ellen M.; Pauw, Wouter; Sturm, Patrick D. J.; Thijsen, Steven F. T.; Kluytmans, Jan A. J. W.; Bonten, Marc J. M.

    2010-01-01

    Rationale: Selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) eradicate gram-negative bacteria (GNB) from the intestinal and respiratory tract in intensive care unit (ICU) patients, but their effect on antibiotic resistance remains controversial. Object

  12. Response in soil of Cupriavidus necator and other copper-resistant bacterial predators of bacteria to addition of water, soluble nutrients, various bacterial species, or Bacillus thuringiensis spores and crystals

    Energy Technology Data Exchange (ETDEWEB)

    Casida, L.E. Jr. (Pennsylvania State Univ., University Park (USA))

    1988-09-01

    Soil was incubated with various species of bacteria, Bacillus subtilis, or Bacillus thuringiensis spores and crystals. These were added to serve as potential prey for indigenous, copper-resistant, nonobligate bacterial predators of bacteria in the soil. Alternatively, the soil was incubated with soluble nutrients or water only to cause potential indigenous prey cells to multiply so the predator cells would multiply. All of these incubation procedures caused excessive multiplication of some gram-negative bacteria in soil. Even greater multiplication, however, often occurred for certain copper-resistant bacterial predators of bacteria that made up a part of the gram-negative response. Incubation of the soil with copper per se did not give these responses. In most cases, the copper-resistant bacteria that responded were Cupriavidus necator, bacterial predator L-2, or previously unknown bacteria that resembled them. The results suggest that, under various conditions of soil incubation, gram-negative bacterial predators of bacteria multiply and that several copper-resistant types among them can be detected, counted, and isolated by plating dilutions of the soil onto media containing excess copper.

  13. Steering Evolution with Sequential Therapy to Prevent the Emergence of Bacterial Antibiotic Resistance.

    Directory of Open Access Journals (Sweden)

    Daniel Nichol

    2015-09-01

    Full Text Available The increasing rate of antibiotic resistance and slowing discovery of novel antibiotic treatments presents a growing threat to public health. Here, we consider a simple model of evolution in asexually reproducing populations which considers adaptation as a biased random walk on a fitness landscape. This model associates the global properties of the fitness landscape with the algebraic properties of a Markov chain transition matrix and allows us to derive general results on the non-commutativity and irreversibility of natural selection as well as antibiotic cycling strategies. Using this formalism, we analyze 15 empirical fitness landscapes of E. coli under selection by different β-lactam antibiotics and demonstrate that the emergence of resistance to a given antibiotic can be either hindered or promoted by different sequences of drug application. Specifically, we demonstrate that the majority, approximately 70%, of sequential drug treatments with 2-4 drugs promote resistance to the final antibiotic. Further, we derive optimal drug application sequences with which we can probabilistically 'steer' the population through genotype space to avoid the emergence of resistance. This suggests a new strategy in the war against antibiotic-resistant organisms: drug sequencing to shepherd evolution through genotype space to states from which resistance cannot emerge and by which to maximize the chance of successful therapy.

  14. Activity of Norspermidine on Bacterial Biofilms of Multidrug-Resistant Clinical Isolates Associated with Persistent Extremity Wound Infections.

    Science.gov (United States)

    Cardile, Anthony P; Woodbury, Ronald L; Sanchez, Carlos J; Becerra, Sandra C; Garcia, Rebecca A; Mende, Katrin; Wenke, Joseph C; Akers, Kevin S

    2016-11-19

    Biofilm formation is a major virulence factor for numerous pathogenic bacteria and is cited as a central event in the pathogenesis of chronic human infections, which is in large part due to excessive extracellular matrix secretion and metabolic changes that occur within the biofilm rendering them highly tolerant to antimicrobial treatments. Polyamines, including norspermidine, play central roles in bacterial biofilm development, but have also recently been shown to inhibit biofilm formation in select strains of various pathogenic bacteria. The aim of this study was to evaluate in vitro the biofilm dispersive and inhibitory activities of norspermidine against multidrug-resistant clinical isolates of Acinetobacter baumannii(n = 4), Klebsiella pneumoniae (n = 3), Pseudomonas aeruginosa (n = 5) and Staphylococcus aureus (n = 4) associated with chronic extremity wound infections using the semi-quantitative 96-well plate method and confocal laser microscopy. In addition to the antibiofilm activity, biocompatibility of norspermidine was also evaluated by measuring toxicity in vitro to human cell lines and whole porcine tissue explants using MTT viability assay and histological analysis. Norspermidine (5-20 mM) had variable dispersive and inhibitory activity on biofilms which was dependent on both the strain and species. Of the clinical bacterial species evaluated herein, A. baumannii isolates were the most sensitive to the effect of norspermidine, which was in part due to the inhibitory effects of norspermidine on bacterial motility and expression of genes involved in the production of homoserine lactones and quorum sensing molecules both essential for biofilm formation. Importantly, exposure of cell lines and whole tissues to norspermidine for prolonged periods of time (≥24 h) was observed to reduce viability and alter tissue histology in a time and concentration dependent manner, with 20 mM exposure having the greatest negative effects on both

  15. Identification of structural traits that increase the antimicrobial activity of a chimeric peptide of human β-defensins 2 and 3.

    Science.gov (United States)

    Spudy, Björn; Sönnichsen, Frank D; Waetzig, Georg H; Grötzinger, Joachim; Jung, Sascha

    2012-10-12

    Antimicrobial peptides participate in the first line of defence of many organisms against pathogens. In humans, the family of β-defensins plays a pivotal role in innate immunity. Two human β-defensins, β-defensin-2 and -3 (HBD2 and HBD3), show substantial sequence identity and structural similarity. However, HBD3 kills Staphylococcus (S.) aureus with a 4- to 8-fold higher efficiency compared to HBD2, whereas their activities against Escherichia (E.) coli are very similar. The generation of six HBD2/HBD3-chimeric molecules led to the identification of distinct molecular regions which mediate their divergent killing properties. One of the chimeras (chimera C3) killed both E. coli and S. aureus with an even higher efficacy compared to the wild-type molecules. Due to the broad spectrum of its antimicrobial activity against many human multidrug-resistant pathogens, this HBD2/HBD3-chimeric peptide represents a promising candidate for a new class of antibiotics. In order to investigate the structural basis of its exceptional antimicrobial activity, the peptide's tertiary structure was determined by NMR spectroscopy, which allowed its direct comparison to the published structures of HBD2 and HBD3 and the identification of the activity-increasing molecular features.

  16. Antibacterial Activity of Defensin PaDef from Avocado Fruit (Persea americana var. drymifolia Expressed in Endothelial Cells against Escherichia coli and Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Jaquelina Julia Guzmán-Rodríguez

    2013-01-01

    Full Text Available Antimicrobial therapy is a useful tool to control infectious diseases in general and rising antibiotic resistant microorganisms in particular. Alternative strategies are desirable, and antimicrobial peptides (AMP represent attractive control agents. Mexican avocado (Persea americana var. drymifolia is used in traditional medicine; however, the AMP production has not been reported in this plant. We obtained a cDNA library from avocado fruit and clone PaDef was identified, which has a cDNA (249 bp encoding a protein (78 aa homologous with plant defensins (>80%. We expressed the defensin PaDef cDNA (pBME3 in the bovine endothelial cell line BVE-E6E7. Polyclonal and clonal populations were obtained and their activity was evaluated against Escherichia coli, Staphylococcus aureus, and Candida albicans. E. coli viability was inhibited with 100 μg/mL of total protein from clones (>55%. Also, S. aureus viability was inhibited from 50 μg/mL total protein (27–38% but was more evident at 100 μg/mL (52–65%. This inhibition was higher than the effect showed by polyclonal population (~23%. Finally, we did not detect activity against C. albicans. These results are the first report that shows antimicrobial activity of a defensin produced by avocado and suggest that this AMP could be used in the control of pathogens.

  17. Antibacterial Activity of Defensin PaDef from Avocado Fruit (Persea americana var. drymifolia) Expressed in Endothelial Cells against Escherichia coli and Staphylococcus aureus

    Science.gov (United States)

    Guzmán-Rodríguez, Jaquelina Julia; López-Gómez, Rodolfo; Suárez-Rodríguez, Luis M.; Salgado-Garciglia, Rafael; Rodríguez-Zapata, Luis C.; Ochoa-Zarzosa, Alejandra; López-Meza, Joel E.

    2013-01-01

    Antimicrobial therapy is a useful tool to control infectious diseases in general and rising antibiotic resistant microorganisms in particular. Alternative strategies are desirable, and antimicrobial peptides (AMP) represent attractive control agents. Mexican avocado (Persea americana var. drymifolia) is used in traditional medicine; however, the AMP production has not been reported in this plant. We obtained a cDNA library from avocado fruit and clone PaDef was identified, which has a cDNA (249 bp) encoding a protein (78 aa) homologous with plant defensins (>80%). We expressed the defensin PaDef cDNA (pBME3) in the bovine endothelial cell line BVE-E6E7. Polyclonal and clonal populations were obtained and their activity was evaluated against Escherichia coli, Staphylococcus aureus, and Candida albicans. E. coli viability was inhibited with 100 μg/mL of total protein from clones (>55%). Also, S. aureus viability was inhibited from 50 μg/mL total protein (27–38%) but was more evident at 100 μg/mL (52–65%). This inhibition was higher than the effect showed by polyclonal population (~23%). Finally, we did not detect activity against C. albicans. These results are the first report that shows antimicrobial activity of a defensin produced by avocado and suggest that this AMP could be used in the control of pathogens. PMID:24319695

  18. Antibacterial activity of defensin PaDef from avocado fruit (Persea americana var. drymifolia) expressed in endothelial cells against Escherichia coli and Staphylococcus aureus.

    Science.gov (United States)

    Guzmán-Rodríguez, Jaquelina Julia; López-Gómez, Rodolfo; Suárez-Rodríguez, Luis M; Salgado-Garciglia, Rafael; Rodríguez-Zapata, Luis C; Ochoa-Zarzosa, Alejandra; López-Meza, Joel E

    2013-01-01

    Antimicrobial therapy is a useful tool to control infectious diseases in general and rising antibiotic resistant microorganisms in particular. Alternative strategies are desirable, and antimicrobial peptides (AMP) represent attractive control agents. Mexican avocado (Persea americana var. drymifolia) is used in traditional medicine; however, the AMP production has not been reported in this plant. We obtained a cDNA library from avocado fruit and clone PaDef was identified, which has a cDNA (249 bp) encoding a protein (78 aa) homologous with plant defensins (>80%). We expressed the defensin PaDef cDNA (pBME3) in the bovine endothelial cell line BVE-E6E7. Polyclonal and clonal populations were obtained and their activity was evaluated against Escherichia coli, Staphylococcus aureus, and Candida albicans. E. coli viability was inhibited with 100 μg/mL of total protein from clones (>55%). Also, S. aureus viability was inhibited from 50 μg/mL total protein (27-38%) but was more evident at 100 μg/mL (52-65%). This inhibition was higher than the effect showed by polyclonal population (~23%). Finally, we did not detect activity against C. albicans. These results are the first report that shows antimicrobial activity of a defensin produced by avocado and suggest that this AMP could be used in the control of pathogens.

  19. [Biotypes and antibiotic resistance patterns of Gardnerella vaginalis strains isolated from healthy women and women with bacterial vaginosis].

    Science.gov (United States)

    Tosun, Ilknur; Alpay Karaoğlu, Sengül; Ciftçi, Hasan; Buruk, Celal Kurtuluş; Aydin, Faruk; Kiliç, Ali Osman; Ertürk, Murat

    2007-01-01

    As Gardnerella vaginalis is accepted as a member of normal vaginal flora, it is one of the dominant species which has been related to bacterial vaginosis (BV). The aim of this study was to determine the isolation rate, biotypes and antibiotic resistance patterns of G.vaginalis from the vaginal swab samples of 408 women who were admitted to the outpatient clinics of Family Planning Center. Hippurate hydrolysis, lipase and beta-galactosidase tests were performed for biotyping the isolates, and agar dilution (for metronidazole) and disk diffusion (for clindamycin) tests were used for the detection of antibiotic resistance patterns. As a result, by Nugent's BV scoring protocol, 122 (29.9%), 20 (29.4%), 137 (33.6%), and 18 (4.4%) of the women were diagnosed as BV, intermediate form, normal vaginal flora (NVF) and mycotic vaginosis, respectively. The overall isolation rate of G.vaginalis was found as 23% (94/408). Of them, 56.4% (53/94) and 8.5% (8/94) were isolated from samples of BV cases and subjects with NVF, respectively, and the difference was statistically significant (pbiotyping results showed that the most frequently detected types were biotype 1 (44%), 5 (20%) and 4 (18%). There was no statistically significant difference between the biotype distribution of BV patients and the subjects who have NVF (p=0.687). The results of antibiotic susceptibility tests indicated that 70% and 53% of the isolates were resistant to metronidazole and clindamycin, respectively. It was of interest that MIC values for metronidazole was > or =128 microg/ml in 57% of resistant strains. The data of this study has emphasized that the metronidazole resistance is very high in our population, and the large scale studies are needed to clarify the relationship between BV and G.vaginalis biotypes, which can be found in the normal vaginal flora.

  20. Combinative effects of a bacterial type-III effector and a biocontrol bacterium on rice growth and disease resistance

    Indian Academy of Sciences (India)

    Haiying Ren; Ganyu Gu; Juying Long; Qian Yin; Tingquan Wu; Tao Song; Shujian Zhang; Zhiyi Chen; Hansong Dong

    2006-12-01

    Expression of HpaGXoo, a bacterial type-III effector, in transgenic plants induces disease resistance. Resistance also can be elicited by biocontrol bacteria. In both cases, plant growth is often promoted. Here we address whether biocontrol bacteria and HpaGXoo can act together to provide better results in crop improvement. We studied effects of Pseudomonas cepacia on the rice variety R109 and the hpaGXoo-expressing rice line HER1. Compared to R109, HER1 showed increased growth, grain yield, and defense responses toward diseases and salinity stress. Colonization of roots by P. cepacia caused 20% and 13% increase, in contrast to controls, in root growth of R109 and HER1. Growth of leaves and stems also increased in R109 but that of HER1 was inhibited. When P. cepacia colonization was subsequent to plant inoculation with Rhizoctonia solani, a pathogen that causes sheath blight, the disease was less severe than controls in both R109 and HER1; HER1, nevertheless, was more resistant, suggesting that P. cepacia and HpaGXoo cooperate in inducing disease resistance. Several genes that critically regulate growth and defense behaved differentially in HER1 and R109 while responding to P. cepacia. In R109 leaves, the OsARF1 gene, which regulates plant growth, was expressed in consistence with growth promotion by P. cepacia. Inversely, OsARF1 expression was coincident with inhibition in growth of HER1 leaves. In both plants, the expression of OsEXP1, which encodes an expansin protein involved in plant growth, was concomitant with growth promotion in leaves instead of roots, in response to P. cepacia. We also studied OsMAPK, a gene that encodes a mitogen-activated protein kinase and controls defense responses toward salinity and infection by pathogens in rice. In response to P. cepacia, an early expression of OsMAPK was coincident with R109 resistance to the disease, while HER1 expressed the gene similarly whether P. cepacia was present or not. Evidently, P. cepacia and GXoo

  1. Mechanisms, molecular and sero-epidemiology of antimicrobial resistance in bacterial respiratory pathogens isolated from Japanese children

    Directory of Open Access Journals (Sweden)

    Sunakawa Keisuke

    2007-08-01

    Full Text Available Abstract Background The clinical management of community-acquired respiratory tract infections (RTIs is complicated by the increasing worldwide prevalence of antibacterial resistance, in particular, β-lactam and macrolide resistance, among the most common causative bacterial pathogens. This study aimed to determine the mechanisms and molecular- and sero-epidemiology of antibacterial resistance among the key paediatric respiratory pathogens in Japan. Methods Isolates were collected at 18 centres in Japan during 2002 and 2003 from children with RTIs as part of the PROTEKT surveillance programme. A proportion of Haemophilus influenzae isolates was subjected to sequencing analysis of the ftsI gene; phylogenetic relatedness was assessed using multilocus sequence typing. Streptococcus pneumoniae isolates were screened for macrolide-resistance genotype by polymerase chain reaction and serotyped using the capsular swelling method. Susceptibility of isolates to selected antibacterials was performed using CLSI methodology. Results and Discussion Of the 557 H. influenzae isolates collected, 30 (5.4% were β-lactamase-positive [BL+], 115 (20.6% were BL-nonproducing ampicillin-resistant (BLNAR; MIC ≥ 4 mg/L and 79 (14.2% were BL-nonproducing ampicillin-intermediate (BLNAI; MIC 2 mg/L. Dabernat Group III penicillin binding protein 3 (PBP3 amino acid substitutions in the ftsI gene were closely correlated with BLNAR status but phylogenetic analysis indicated marked clonal diversity. PBP mutations were also found among BL+ and BL-nonproducing ampicillin-sensitive isolates. Of the antibacterials tested, azithromycin and telithromycin were the most active against H. influenzae (100% and 99.3% susceptibility, respectively. A large proportion (75.2% of the 468 S. pneumoniae isolates exhibited macrolide resistance (erythromycin MIC ≥ 1 mg/L; erm(B was the most common macrolide resistance genotype (58.8%, followed by mef(A (37.2%. The most common pneumococcal

  2. Cloning and Expression of β-Defensin from Soiny Mullet (Liza haematocheila), with Insights of its Antibacterial Mechanism

    Science.gov (United States)

    Qi, Zhitao; Xu, Wei; Meng, Fancui; Zhang, Qihuan; Chen, Chenglung; Shao, Rong

    2016-01-01

    Beta-defensins are important part of innate immunity of fish, which are the first defense line against invading pathogens. In this study, the β-defensin (Lhβ-defensin) gene was cloned from spleen tissue of soiny mullet (Liza haematocheila). Lhβ-defensin cDNA was 747 bp in length, encoding 63 amino acids. Sequence alignment revealed that Lhβ-defensin contained six conserved cysteine residues and shared 97.5% sequence identities with grouper (Epinephelus coioides) β-defensin. Realtime PCR revealed that Lhβ-defensin was highest expressed in the immune related organs, such as spleen, kidney and gut of healthy fish. Following Streptococcus dysgalactiae infection, Lhβ-defensin was up-regulated in immune related organs, e.g. 17.6-fold in spleen and 10.87-fold in gut at 24 h post infection (hpi). Lhβ-defensin possessed a monomeric structure of a three-stranded anti-parallel β-sheet and an α-helix stabilized by three disulfide bonds formed by Cys30-Cys58, Cys36-Cys52, and Cys40-Cys59. In addition to the experimental work, computer simulation was also carried out to determine the possible conformation of β-defensin and its interaction with palmitoyloleoylphosphatidylglycerol (POPG), a model of bacteria membrane. The Lhβ-defensin was found to form dimeric structure stabilized by the van der Waals contacts of Leu35 and Cys37 in two anti-parallel β1-strands and the cation-π interaction between Tyr32 and Arg54 respectively in the two β1-strands. The most important interactions between β-defensin and membrane are the electrostatic interactions between Arg residues in β-defensin and head group of POPG bilayer as well as hydrogen bond interactions between them. Our results were useful for further understanding the potential mechanism of antimicrobial property of fish β-defensins. PMID:27322675

  3. Modelling the influence of the sporulation temperature upon the bacterial spore heat resistance, application to heating process calculation.

    Science.gov (United States)

    Leguérinel, I; Couvert, O; Mafart, P

    2007-02-28

    Environmental conditions of sporulation influence bacterial heat resistance. For different Bacillus species a linear Bigelow type relationship between the logarithm of D values determined at constant heating temperature and the temperature of sporulation was observed. The absence of interaction between sporulation and heating temperatures allows the combination of this new relationship with the classical Bigelow model. The parameters zT and zT(spo) of this global model were fitted to different sets of data regarding different Bacillus species: B. cereus, B. subtilis, B. licheniformis, B. coagulans and B. stearothermophilus. The origin of raw products or food process conditions before a heat treatment can lead to warm temperature conditions of sporulation and to a dramatic increase of the heat resistance of the generated spores. In this case, provided that the temperature of sporulation can be assessed, this model can be easily implemented to rectify F values on account of possible increase of thermal resistance of spores and to ensure the sterilisation efficacy.

  4. Tetracyclines in Food and Feedingstuffs: From Regulation to Analytical Methods, Bacterial Resistance, and Environmental and Health Implications

    Directory of Open Access Journals (Sweden)

    Fabio Granados-Chinchilla

    2017-01-01

    Full Text Available Antibiotics are widely used as growth promoters in animal husbandry; among them, the tetracyclines are a chemical group of relevance, due to their wide use in agriculture, surpassing in quantities applied almost every other antibiotic family. Seeing the considerable amounts of tetracyclines used worldwide, monitoring of these antibiotics is paramount. Advances must be made in the analysis of antibiotics to assess correct usage and dosage of tetracyclines in food and feedstuffs and possible residues in pertinent environmental samples. The tetracyclines are still considered a clinically relevant group of antibiotics, though dissemination of tolerance and resistance determinants have limited their use. This review focuses on four different aspects: (i tetracyclines, usage, dosages, and regulatory issues that govern their food-related application, with particular attention to the prohibitions and restrictions that several countries have enforced in recent years by agencies from both the United States and the European Union, (ii analytical methods for tetracyclines, determination, and residues thereof in feedstuffs and related matrices with an emphasis on the most relevant and novel techniques, including both screening and confirmatory methods, (iii tetracycline resistance and tetracycline-resistant bacteria in feedstuff, and (iv environmental and health risks accompanying the use of tetracyclines in animal nutrition. In the last two cases, we discuss the more relevant undesirable effects that tetracyclines exert over bacterial communities and nontarget species including unwanted effects in farmers.

  5. In vitro effectiveness of the antimicrobial peptide eCATH1 against antibiotic-resistant bacterial pathogens of horses.

    Science.gov (United States)

    Schlusselhuber, Margot; Guldbech, Kristen; Sevin, Corinne; Leippe, Matthias; Petry, Sandrine; Grötzinger, Joachim; Giguère, Steeve; Cauchard, Julien

    2014-01-01

    The equine antimicrobial peptide eCATH1 previously has been shown to have in vitro activity against antibiotic-susceptible reference strains of Rhodococcus equi and common respiratory bacterial pathogens of foals. Interestingly, eCATH1 was also found to be effective in the treatment of R. equi infection induced in mice. The aim of this study was to assess the in vitro activity of eCATH1 against equine isolates of Gram-negative (Escherichia coli, Salmonella enterica, Klebsiella pneumoniae and Pseudomonas spp.) and Gram-positive (R. equi, Staphylococcus aureus) bacteria resistant to multiple classes of conventional antibiotics. A modified microdilution method was used to evaluate the minimum inhibitory concentrations (MICs) of the antimicrobial peptide. The study revealed that eCATH1 was active against all equine isolates of E. coli, S. enterica, K. pneumoniae, Pseudomonas spp. and R. equi tested, with MICs of 0.5-16 μg mL(-1), but was not active against most isolates of S. aureus. In conclusion, the activity of the equine antimicrobial peptide eCATH1 appears to not be hampered by the antibiotic resistance of clinical isolates. Thus, the data suggest that eCATH1 could be useful, not only in the treatment of R. equi infections, but also of infections caused by multidrug-resistant Gram-negative pathogens.

  6. Tetracyclines in Food and Feedingstuffs: From Regulation to Analytical Methods, Bacterial Resistance, and Environmental and Health Implications

    Science.gov (United States)

    Granados-Chinchilla, Fabio

    2017-01-01

    Antibiotics are widely used as growth promoters in animal husbandry; among them, the tetracyclines are a chemical group of relevance, due to their wide use in agriculture, surpassing in quantities applied almost every other antibiotic family. Seeing the considerable amounts of tetracyclines used worldwide, monitoring of these antibiotics is paramount. Advances must be made in the analysis of antibiotics to assess correct usage and dosage of tetracyclines in food and feedstuffs and possible residues in pertinent environmental samples. The tetracyclines are still considered a clinically relevant group of antibiotics, though dissemination of tolerance and resistance determinants have limited their use. This review focuses on four different aspects: (i) tetracyclines, usage, dosages, and regulatory issues that govern their food-related application, with particular attention to the prohibitions and restrictions that several countries have enforced in recent years by agencies from both the United States and the European Union, (ii) analytical methods for tetracyclines, determination, and residues thereof in feedstuffs and related matrices with an emphasis on the most relevant and novel techniques, including both screening and confirmatory methods, (iii) tetracycline resistance and tetracycline-resistant bacteria in feedstuff, and (iv) environmental and health risks accompanying the use of tetracyclines in animal nutrition. In the last two cases, we discuss the more relevant undesirable effects that tetracyclines exert over bacterial communities and nontarget species including unwanted effects in farmers. PMID:28168081

  7. Double-Stranded RNA-Binding Protein 4 Is Required for Resistance Signaling against Viral and Bacterial Pathogens

    Directory of Open Access Journals (Sweden)

    Shifeng Zhu

    2013-09-01

    Full Text Available Plant viruses often encode suppressors of host RNA silencing machinery, which occasionally function as avirulence factors that are recognized by host resistance (R proteins. For example, the Arabidopsis R protein, hypersensitive response to TCV (HRT, recognizes the turnip crinkle virus (TCV coat protein (CP. HRT-mediated resistance requires the RNA-silencing component double-stranded RNA-binding protein 4 (DRB4 even though it neither is associated with the accumulation of TCV-specific small RNA nor requires the RNA silencing suppressor function of CP. HRT interacts with the cytosolic fraction of DRB4. Interestingly, TCV infection both increases the cytosolic DRB4 pool and inhibits the HRT-DRB4 interaction. The virulent R8A CP derivative, which induces a subset of HRT-derived responses, also disrupts this interaction. The differential localization of DRB4 in the presence of wild-type and R8A CP implies the importance of subcellular compartmentalization of DRB4. The requirement of DRB4 in resistance to bacterial infection suggests a universal role in R-mediated defense signaling.

  8. 越南对抗角斑病棉花品种的选育(英)%Screening of Promising Cotton Varieties for Bacterial Blight Resistance

    Institute of Scientific and Technical Information of China (English)

    Bui Thi Ngan

    2002-01-01

    @@ I Introduction Bacterial Blight (Xanthomonas malvacearum ,BB) was probably originated in India, although the disease was first reported in the USA by Atkinson (1891), who gave the names angular leaf spot, blackarm and bacterial boll rot to the various stages in the syndrome of the disease. The first programme to breed for cultivar resistance to the disease was initiated in Sudan by research officers with the Cotton Research Corporation. Methods adopted there were soon implemented in Uganda and most of the early resistant varieties grown in many African countries were derived from the Uganda programme.

  9. Forging a link between bacterial biofilms and drug resistance: an unsolved mystery

    Directory of Open Access Journals (Sweden)

    Pallavi Sayal

    2016-12-01

    Conclusions: The armament of various bacteriostatic or bactericidal agents available to treat infections are restricted to act in planktonic phase and these agents did not take into account the unique biology of bacterial biofilms. Thus, bacteria growing as biofilm communities often result in troublesome complications as persistent infections, which cannot be resolved with standard antibiotic treatments. As, biofilm communities embedded in exopolysaccharide have not been considered until recently, therapeutic strategies to treat them are not available yet. [Int J Res Med Sci 2016; 4(12.000: 5341-5344

  10. Bacterial viruses enable their host to acquire antibiotic resistance genes from neighbouring cells

    DEFF Research Database (Denmark)

    Haaber, Jakob Krause; Leisner, Jørgen; Cohn, Marianne Thorup

    2016-01-01

    Prophages are quiescent viruses located in the chromosomes of bacteria. In the human pathogen, Staphylococcus aureus, prophages are omnipresent and are believed to be responsible for the spread of some antibiotic resistance genes. Here we demonstrate that release of phages from a subpopulation of S....... aureus cells enables the intact, prophage-containing population to acquire beneficial genes from competing, phage-susceptible strains present in the same environment. Phage infection kills competitor cells and bits of their DNA are occasionally captured in viral transducing particles. Return...... of such particles to the prophage-containing population can drive the transfer of genes encoding potentially useful traits such as antibiotic resistance. This process, which can be viewed as ‘auto-transduction’, allows S. aureus to efficiently acquire antibiotic resistance both in vitro and in an in vivo virulence...

  11. The Role of Antimicrobial Peptides in Preventing Multidrug-Resistant Bacterial Infections and Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Kyung-Soo Hahm

    2011-09-01

    Full Text Available Over the last decade, decreasing effectiveness of conventional antimicrobial-drugs has caused serious problems due to the rapid emergence of multidrug-resistant pathogens. Furthermore, biofilms, which are microbial communities that cause serious chronic infections and dental plaque, form environments that enhance antimicrobial resistance. As a result, there is a continuous search to overcome or control such problems, which has resulted in antimicrobial peptides being considered as an alternative to conventional drugs. Antimicrobial peptides are ancient host defense effector molecules in living organisms. These peptides have been identified in diverse organisms and synthetically developed by using peptidomimic techniques. This review was conducted to demonstrate the mode of action by which antimicrobial peptides combat multidrug-resistant bacteria and prevent biofilm formation and to introduce clinical uses of these compounds for chronic disease, medical devices, and oral health. In addition, combinations of antimicrobial peptides and conventional drugs were considered due to their synergetic effects and low cost for therapeutic treatment.

  12. Antibiotic reduction campaigns do not necessarily decrease bacterial resistance: the example of methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Kardas-Sloma, Lidia; Boëlle, Pierre-Yves; Opatowski, Lulla; Guillemot, Didier; Temime, Laura

    2013-09-01

    Interventions designed to reduce antibiotic consumption are under way worldwide. While overall reductions are often achieved, their impact on the selection of antibiotic-resistant selection cannot be assessed accurately from currently available data. We developed a mathematical model of methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA) transmission inside and outside the hospital. A systematic simulation study was then conducted with two objectives: to assess the impact of antibiotic class-specific changes during an antibiotic reduction period and to investigate the interactions between antibiotic prescription changes in the hospital and the community. The model reproduced the overall reduction in MRSA frequency in French intensive-care units (ICUs) with antibiotic consumption in France from 2002 to 2003 as an input. However, the change in MRSA frequency depended on which antibiotic classes changed the most, with the same overall 10% reduction in antibiotic use over 1 year leading to anywhere between a 69% decrease and a 52% increase in MRSA frequency in ICUs and anywhere between a 37% decrease and a 46% increase in the community. Furthermore, some combinations of antibiotic prescription changes in the hospital and the community could act in a synergistic or antagonistic way with regard to overall MRSA selection. This study shows that class-specific changes in antibiotic use, rather than overall reductions, need to be considered in order to properly anticipate the impact of an antibiotic reduction campaign. It also highlights the fact that optimal gains will be obtained by coordinating interventions in hospitals and in the community, since the effect of an intervention in a given setting may be strongly affected by exogenous factors.

  13. A molecular study on bacterial resistance to arsenic-toxicity in surface and underground waters of Latium (Italy).

    Science.gov (United States)

    Davolos, Domenico; Pietrangeli, Biancamaria

    2013-10-01

    Latium, a region in central Italy, is known for its extensive volcanic areas that make a significant contribution to the arsenic (As) contamination of freshwater environments, even though some degree of As water pollution may be caused by human activities. The information available on indigenous As-resistant prokaryotes in aquatic environments of Latium is, however, still limited. In this study, we describe new bacteria that are resistant to arsenic toxicity and were isolated from the surface waters of Lake Vico and the Sacco River, two groundwater systems in Latium, as well as from bottled natural mineral water from the same region. The 16S rRNA gene sequence analysis for the As-resistant strains in lake and river waters points to a prevalence of β- and γ-Proteobacteria, while α-Proteobacteria, Firmicutes and Bacteroidetes are represented to a lesser extent. By contrast, solely γ-Proteobacteria were isolated from groundwater samples. The presence of Actinobacteria was documented exclusively in bottled mineral water. In addition, we conducted a DNA sequence-based study on the gene codifying arsB, an As(III) efflux membrane protein pump related to arsenic resistance, for all the As-resistant bacterial isolates. A phylogenetic analysis was carried out on the newly sequenced 16S rRNA genes and arsB in the present study as well as on an additional 16S rRNA/arsB dataset we obtained previously from Lake Albano, from the Tiber and from a well in Bassano Romano located in Latium (Davolos and Pietrangeli, 2011). Overall, the phylogenetic diversity of As-resistant bacteria in underground water was very limited if compared with lentic and lotic waters. Lastly, our molecular data support the hypothesis that the horizontal gene transfer of ars in As-containing freshwater environments is not limited to closely-related genomes, but also occurs between bacteria that are distant from an evolutionary viewpoint, thereby indicating that such genetic events may be considered a

  14. Rising bacterial resistance to common antibiotics in Al Ain, United Arab Emirates.

    Science.gov (United States)

    Al-Kaabi, M R; Tariq, W U-Z; Hassanein, A A

    2011-06-01

    There is a dearth of local information in Al Amin, United Arab Emirates about antibiotic resistance patterns. In this retrospective study in a tertiary referral hospital, antibiotic susceptibility results were analysed over the 5-year period 2004-08 and compared with a previous study in the same hospital during 1999-2002. Staphylococcus aureus showed a significant decrease in sensitivity to oxacillin from 95.0% in the period 1999-2002 to 84.4% in 2008. Sensitivity of Acinetobacter spp. to imipenem dropped from 99.0% in 2004 to only 32.5% in 2008. During the same period, almost half of Escherichia coli isolates developed resistance to cefotoxime. Significant reductions in sensitivity to Pseudomonas aeruginosa between 1999 and 2008 were found for almost all the antibiotics tested. Klebsiella spp. did not show any significant change in resistance to any of the tested antibiotics. Serious efforts are needed to reduce the risk of the spread of resistant strains of bacteria.

  15. Identification of New Drug Targets in Multi-Drug Resistant Bacterial Infections

    Science.gov (United States)

    2012-10-01

    COVERED 26 September 2011 25 September 2012 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Identification of New Drug Targets in Multi-Drug Resistant...will be necessary for the fragment based screening and subsequent design of new drug lead compounds. To accompany and validate the structural studies

  16. Bacterial viruses enable their host to acquire antibiotic resistance genes from neighbouring cells

    DEFF Research Database (Denmark)

    Haaber, Jakob; Leisner, Jørgen J; Cohn, Marianne T;

    2016-01-01

    Prophages are quiescent viruses located in the chromosomes of bacteria. In the human pathogen, Staphylococcus aureus, prophages are omnipresent and are believed to be responsible for the spread of some antibiotic resistance genes. Here we demonstrate that release of phages from a subpopulation of S...

  17. Bacterial viruses enable their host to acquire antibiotic resistance genes from neighbouring cells

    DEFF Research Database (Denmark)

    Haaber, Jakob Krause; Leisner, Jørgen; Cohn, Marianne Thorup;

    2016-01-01

    Prophages are quiescent viruses located in the chromosomes of bacteria. In the human pathogen, Staphylococcus aureus, prophages are omnipresent and are believed to be responsible for the spread of some antibiotic resistance genes. Here we demonstrate that release of phages from a subpopulation of...

  18. Biosorption of Zinc (Zn) and lead (Pb) by metal resistant bacterial isolate from mining tail

    Energy Technology Data Exchange (ETDEWEB)

    Bautista Hernandez, D. A.; Carranza Alvarado, M.; Fernandez Linares, L.; Ramirez Landy, I.

    2009-07-01

    The use of microbial biomass in the removal of metals in solution, mainly of low concentrations (100 mg L{sup -}1), present advantages in relation to the physicochemical methods. The resistant microorganisms are potential bio sorbents. The objective of the present study was the isolation, starting from mining tail, of strains with capacity of metal bio sorption (Zn and Pb). (Author)

  19. Characterization of plasmids that encode streptomycin-resistance in bacterial epiphytes of apple.

    Science.gov (United States)

    Huang, T C; Burr, T J

    1999-05-01

    Streptomycin resistance in strains of Pseudomonas syringae pv. papulans, Pantoea agglomerans and a yellow-pigmented, non-fluorescent Pseudomonas sp. (Py), isolated from apple orchards in New York and Washington states, is predominantly associated with strA-strB genes carried on conjugal plasmids (R plasmids). None of 128 resistant Erwinia amylovora strains from the eastern and western USA hybridized with a strA-strB probe, SMP3. Resistant Py strains transfered R plasmids to Ps. syringae pv. papulans and to Py in vitro at frequencies of 10(-1)-10(-2) per recipient cell whereas Ps. syringae pv. papulans transferred its plasmids at frequencies of 10(-2) to below detectable levels. Transfer of R plasmids to P. agglomerans was not detected and resistant P. agglomerans did not transfer their R plasmids to any recipients. R plasmids were found to be highly diverse as measured by DNA fingerprint analysis. Transfer-deficient transposon mutants of R plasmid pCPP519 were generated, and 3.9 kb EcoRI and 3.0 kb SmaI fragments that hybridized with a Tn5 probe were cloned and sequenced. The deduced amino acid sequences of the 3.9 kb fragment were similar to proteins involved in replication, nicking at oriT, and piliation in other bacteria.

  20. Selenium hyperaccumulators harbor a diverse endophytic bacterial community characterized by high selenium resistance and plant growth promoting properties

    Directory of Open Access Journals (Sweden)

    Martina eSura - de Jong

    2015-03-01

    Full Text Available Selenium (Se-rich plants may be used to provide dietary Se to humans and livestock, and also to clean up Se-polluted soils or waters. This study focused on endophytic bacteria of plants that hyperaccumulate selenium (Se to 0.5-1% of dry weight. Terminal restriction fragment length polymorphism (T-RFLP analysis was used to compare the diversity of endophytic bacteria of hyperaccumulators Stanleya pinnata (Brassicaceae and Astragalus bisulcatus (Fabaceae with those from related non-accumulators Physaria bellii (Brassicaceae and Medicago sativa (Fabaceae collected on the same, seleniferous site. Hyperaccumulators and non-accumulators showed equal T-RF diversity. Parsimony analysis showed that T-RFs from individuals of the same species were more similar to each other than to those from other species, regardless of plant Se content or spatial proximity. Cultivable endophytes from hyperaccumulators S. pinnata and A. bisulcatus were further identified and characterized. The 66 bacterial morphotypes were shown by MS MALDI-TOF Biotyper analysis and 16S rRNA gene sequencing to include strains of Bacillus, Pseudomonas, Pantoea, Staphylococcus, Paenibacillus, Advenella, Arthrobacter and Variovorax. Most isolates were highly resistant to selenate and selenite (up to 200 mM and all could reduce selenite to red elemental Se, reduce nitrite and produce siderophores. Seven isolates were selected for plant inoculation and found to have plant growth promoting properties, both in pure culture and when co-cultivated with crop species Brassica juncea (Brassicaceae or M. sativa. There were no effects on plant Se accumulation. We conclude that Se hyperaccumulators harbor an endophytic bacterial community in their natural seleniferous habitat that is equally diverse to that of comparable non-accumulators. The hyperaccumulator endophytes are characterized by high Se resistance, capacity to produce elemental Se and plant growth promoting properties.

  1. Changes of bacterial diversity and tetracycline resistance in sludge from AAO systems upon exposure to tetracycline pressure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Manhong, E-mail: egghmh@163.com; Qi, Fangfang; Wang, Jue; Xu, Qi; Lin, Li

    2015-11-15

    Highlights: • High-throughput sequencing was used to compare sludge bacteria with and without TC. • Bacterial diversity increased with TC addition despite of various oxygen conditions. • Total TRGs proliferated with TC addition in three kinds of sludge. • The concentration of efflux pump genes was the highest in the three groups of TRGs. - Abstract: Two lab-scale anaerobic-anoxic-oxic (AAO) systems were used to investigate the changes in tetracycline (TC) resistance and bacterial diversity upon exposure to TC pressure. High-throughput sequencing was used to detect diversity changes in microorganisms at the level of class in sludge from different bioreactors with and without TC. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect the abundances of eight tetracycline resistance genes (TRGs), tetA, tetB, tetC, tetE, tetM, tetO, tetS and tetX. The results showed that the diversities of the microbial communities of anoxic, anaerobic and aerobic sludge all increased with the addition of TC. TC substantially changed the structure of the microbial community regardless of oxygen conditions. Bacteroidetes and Proteobacteria were the dominant species in the three kinds of sludge and were substantially enriched with TC pressure. In sludge with TC added, almost all target TRGs proliferated more than those in sludge without TC except tetX, which decreased in anaerobic sludge with TC addition. The concentration of efflux pump genes, tet(A–C, E), was the highest among the three groups of TRGs in the different kinds of sludge.

  2. Bacterial antagonists of fungal pathogens also control root-knot nematodes by induced systemic resistance of tomato plants.

    Science.gov (United States)

    Adam, Mohamed; Heuer, Holger; Hallmann, Johannes

    2014-01-01

    The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

  3. Bacterial antagonists of fungal pathogens also control root-knot nematodes by induced systemic resistance of tomato plants.

    Directory of Open Access Journals (Sweden)

    Mohamed Adam

    Full Text Available The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

  4. BACTERIAL PROFILE, ANTIBIOTIC SENSITIVITY AND RESISTANCE OF LOWER RESPIRATORY TRACT INFECTIONS IN UPPER EGYPT

    Directory of Open Access Journals (Sweden)

    Gamal Agmy

    2013-09-01

    Full Text Available BACKGROUND: Lower respiratory tract infections (LRTI account for a considerable proportion of morbidity and antibiotic use. We aimed to identify the causative bacteria, antibiotic sensitivity and resistance of hospitalized adult patients due to LRTI in Upper Egypt. METHODS: A multicentre prospective study was performed at 3 University Hospitals for 3 years. Samples included sputum or bronchoalveolar lavage (BAL for staining and culture, and serum for serology. Samples were cultured on 3 bacteriological media (Nutrient, Chocolate ,MacConkey's agars.Colonies were identified via MicroScan WalkAway-96. Pneumoslide IgM kit was used for detection of atypical pathogens via indirect immunofluorescent assay. RESULTS: The predominant isolates in 360 patients with CAP were S.pneumoniae (36%, C. pneumoniae (18%, and M. pneumoniae (12%. A higher sensitivity was recorded for moxifloxacin, levofloxacin, macrolides, and cefepime. A higher of resistance was recorded for doxycycline, cephalosporins, and β-lactam-β-lactamase inhibitors. The predominant isolates in 318 patients with HAP were, methicillin-resistant Staphylococcus aureus; MRSA (23%, K. pneumoniae (14%, and polymicrobial in 12%. A higher sensitivity was recorded for vancomycin, ciprofloxacin, and moxifloxacin. Very high resistance was recorded for β-lactam-β-lactamase inhibitors and cephalosporins. The predominant organisms in 376 patients with acute exacerbation of chronic obstructive pulmonary diseases (AECOPD were H. influnzae (30%, S. pneumoniae (25%, and M. catarrhalis(18%. A higher sensitivity was recorded for moxifloxacin, macrolides and cefepime. A higher rate of resistance was recorded for aminoglycosides and cephalosporins CONCLUSIONS: The most predominant bacteria for CAP in Upper Egypt are S. pneumoniae and atypical organisms, while that for HAP are MRSA and Gram negative bacteria. For acute exacerbation of COPD,H.influnzae was the commonest organism. Respiratory quinolones

  5. Overexpressing CYP71Z2 enhances resistance to bacterial blight by suppressing auxin biosynthesis in rice.

    Directory of Open Access Journals (Sweden)

    Wenqi Li

    Full Text Available The hormone auxin plays an important role not only in the growth and development of rice, but also in its defense responses. We've previously shown that the P450 gene CYP71Z2 enhances disease resistance to pathogens through regulation of phytoalexin biosynthesis in rice, though it remains unclear if auxin is involved in this process or not.The expression of CYP71Z2 was induced by Xanthomonas oryzae pv. oryzae (Xoo inoculation was analyzed by qRT-PCR, with GUS histochemical staining showing that CYP71Z2 expression was limited to roots, blades and nodes. Overexpression of CYP71Z2 in rice durably and stably increased resistance to Xoo, though no significant difference in disease resistance was detected between CYP71Z2-RNA interference (RNAi rice and wild-type. Moreover, IAA concentration was determined using the HPLC/electrospray ionization/tandem mass spectrometry system. The accumulation of IAA was significantly reduced in CYP71Z2-overexpressing rice regardless of whether plants were inoculated or not, whereas it was unaffected in CYP71Z2-RNAi rice. Furthermore, the expression of genes related to IAA, expansin and SA/JA signaling pathways was suppressed in CYP71Z2-overexpressing rice with or without inoculation.These results suggest that CYP71Z2-mediated resistance to Xoo may be via suppression of IAA signaling in rice. Our studies also provide comprehensive insight into molecular mechanism of resistance to Xoo mediated by IAA in rice. Moreover, an available approach for understanding the P450 gene functions in interaction between rice and pathogens has been provided.

  6. BACTERIAL CAUSES OF LOWER RESPIRATORY TRACT INFECTIONS IN PATIENTS ATTENDING CENTRAL REFERRAL HOSPITAL, GANGTOK WITH REFERENCE TO ANTIBIOTIC RESISTANCE PATTERN

    Directory of Open Access Journals (Sweden)

    Priyanka Paul

    2013-10-01

    Full Text Available ABSTRACT: BACKGROUND: There is inadequate information from India on various lower respiratory tract pathogens and their resistance pattern in hospital settings. The present study was undertaken to see the bacteriological profile an d the antibiotic resistance pattern of the isolates causing LRTI from this geographic region. OBJECTIVE: To identify and characterize bacterial pathogens causing community acquired and hospital acquired infections with reference to antibiogram pattern. MET HODS: A total of 137 samples from patients suffering from lower respiratory tract infections were studied. All the sputum samples were subjected to gram staining, culture. Various organisms were identified by standard methods. The Kirby – Bauer method was e mployed to perform the antibiotic sensitivity on Mueller Hinton agar [MHA]. For Streptococcus pneumoniae blood agar was used. MHA with 4% NaCl was used to detect methicillin resistant Staphylococcus aureus [MRSA]. RESULTS: Growth of pathogens was obtained in 66.4% of sputum samples in case of inpatients and in 33.5% outpatients. Klebsiella pneumonia [15.3%] was the predominant isolate among the inpatients whereas Streptococcus pneumonia [8.5%] was the most common pathogen isolated from outpatients. Haemophi lus influenzae was not isolated. Quinolone was found to be most effective antibiotic against gram negative organi sms. A single isolate of Morax ella catarrhalis was isolated from a case of MDR - TB. CONCLUSION : Culture and susceptibility reports should be enc ouraged before therapy to combat the problem of emergence of MDR, ESBL and MRSA strains and to subside the economic burden due to increase in cost according to the consequence of development of antibiotic resistant microbial strains

  7. Inducible expression of beta defensins by human respiratory epithelial cells exposed to Aspergillus fumigatus organisms

    Directory of Open Access Journals (Sweden)

    Tichanné-Seltzer Virginie

    2009-02-01

    Full Text Available Abstract Background Aspergillus fumigatus, a saprophytic mould, is responsible for life-threatening, invasive pulmonary diseases in immunocompromised hosts. The role of the airway epithelium involves a complex interaction with the inhaled pathogen. Antimicrobial peptides with direct antifungal and chemotactic activities may boost antifungal immune response. Results The inducible expression of defensins by human bronchial epithelial 16HBE cells and A549 pneumocyte cells exposed to A. fumigatus was investigated. Using RT-PCR and real time PCR, we showed an activation of hBD2 and hBD9 defensin genes: the expression was higher in cells exposed to swollen conidia (SC, compared to resting conidia (RC or hyphal fragments (HF. The kinetics of defensin expression was different for each one, evoking a putative distinct function for each investigated defensin. The decrease of defensin expression in the presence of heat-inactivated serum indicated a possible link between defensins and the proteins of the host complement system. The presence of defensin peptide hBD2 was revealed using immunofluorescence that showed a punctual cytoplasmic and perinuclear staining. Quantification of the cells stained with anti hBD2 antibody demonstrated that SC induced a greater number of cells that synthesized hBD2, compared to RC or HF. Labelling of the cells with anti-hBD-2 antibody showed a positive immunofluorescence signal around RC or SC in contrast to HF. This suggests co-localisation of hBD2 and digested conidia. The HBD2 level was highest in the supernatants of cells exposed to SC, as was determined by sandwich ELISA. Experiments using neutralising anti-interleukine-1β antibody reflect the autocrine mechanism of defensin expression induced by SC. Investigation of defensin expression at transcriptional and post-transcriptional levels demonstrated the requirement of transcription as well as new protein synthesis during A. fumigatus defensin induction. Finally, induced

  8. Acute bacterial meningitis caused by Streptococcus pneumoniae resistant to the antimicrobian agents and their serotypes Meningite bacteriana aguda por Streptococcus pneumoniae resistente aos antimicrobianos e seus sorotipos

    OpenAIRE

    Andrea Maciel de Oliveira Rossoni; Libera Maria Dalla Costa; Denize Bonato Berto; Sônia Santos Farah; Marilene Gelain; Maria Cristina de Cunto Brandileone; Vitor Hugo Mariano Ramos; Sergio Monteiro de Almeida

    2008-01-01

    The main objectives of this study are to evaluate the resistance rates of Streptococcus pneumonia to penicillin G, ceftriaxone and vancomycin in patients with meningitis; to analyze possible risk factors to the antimicrobian resistance; to describe the serotypes detected and to suggest an initial empirical treatment for meningitis. The sensitiveness and serotypes of all isolated S. pneumoniae of patients with acute bacterial meningitis received by the Paraná State Central Laboratory from Apri...

  9. Evaluation of antibacterial efficacy of anise wastes against some multidrug resistant bacterial isolates

    Directory of Open Access Journals (Sweden)

    Mohamed Khaled Ibrahim

    2017-01-01

    Full Text Available Antibiotic resistance in bacteria is becoming a serious problem, especially after the emergence of multidrug-resistant strains. To overcome this problem, new and effective antibacterials or resistance modulators are highly needed and plant kingdom represents a valuable source of these compounds. In this study we investigated the antibacterial and resistance modulatory activity of Aniseeds waste Residue Extract (ASWRE and Star Anise Waste Residue Extract (SAWRE (post-distillation against 100 isolates belonging to two Gram positive (Streptococcus pneumoniae and Staphylococcus aureus and four Gram negative bacteria (Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa. Phenolic compounds of anise wastes were determined by HPLC. The antibacterial activity of anise waste extracts assays were performed by using inhibition zone diameters, MIC and MBC. Evaluation of synergy interaction between anise waste extracts and certain known antibacterial drugs like Cephradine, Chloramphenicol, Tetracycline and Amoxicillin was carried out using disc diffusion method, MIC and the fractional inhibitory concentrations (FIC. The results showed that HPLC method has been developed for the determination of 25 phenolic compounds from waste extracts. Both ASWRE and SAWRE have significant antibacterial activity against all of the test bacteria. SAWRE was found to have higher amounts of phenolic compounds contents that might be responsible for their comparatively higher antibacteria activity than ASWRE. Irradiation at 10 and 30 kGy did not significantly affect the antibacterial activity of both ASWRE and SAWRE. The combination of anise waste extracts and the tested antibiotics mostly showed synergistic effect. Synergistic interaction was most expressed against Streptococcus pneumoniae (Sp1 and Staphylococcus aureus (Sa1 by Tetracycline and chloramphenicol; Pseudomonas aeruginosa (P2, Klebsiella pneumoniae (K3, Acinetobacter baumannii

  10. Country-to-country transfer of patients and the risk of multi-resistant bacterial infection.

    Science.gov (United States)

    Rogers, Benjamin A; Aminzadeh, Zohreh; Hayashi, Yoshiro; Paterson, David L

    2011-07-01

    Management of patients with a history of healthcare contact in multiple countries is now a reality for many clinicians. Leisure tourism, the burgeoning industry of medical tourism, military conflict, natural disasters, and changing patterns of human migration may all contribute to this emerging epidemiological trend. Such individuals may be both vectors and victims of healthcare-associated infection with multiresistant bacteria. Current literature describes intercountry transfer of multiresistant Acinetobacter spp and Klebsiella pneumoniae (including Klebsiella pneumoniae carbapenemase- and New Delhi metallo-β-lactamase-producing strains), methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and hypervirulent Clostridium difficile. Introduction of such organisms to new locations has led to their dissemination within hospitals. Healthcare institutions should have sound infection prevention strategies to mitigate the risk of dissemination of multiresistant organisms from patients who have been admitted to hospitals in other countries. Clinicians may also need to individualize empiric prescribing patterns to reflect the risk of multiresistant organisms in these patients.

  11. Sterilization of hydrogen peroxide resistant bacterial spores with stabilized chlorine dioxide.

    Science.gov (United States)

    Friedline, Anthony; Zachariah, Malcolm; Middaugh, Amy; Heiser, Matt; Khanna, Neeraj; Vaishampayan, Parag; Rice, Charles V

    2015-01-01

    Bacillus pumilus SAFR-032 spores isolated from a clean room environment are known to exhibit enhanced resistance to peroxide, desiccation, UV radiation and chemical disinfection than other spore-forming bacteria. The survival of B. pumilus SAFR-032 spores to standard clean room sterilization practices requires development of more stringent disinfection agents. Here, we report the effects of a stabilized chlorine dioxide-based biocidal agent against spores of B. pumilus SAFR-032 and Bacillus subtilis ATCC 6051. Viability was determined via CFU measurement after exposure. Chlorine dioxide demonstrated efficacy towards sterilization of spores of B. pumilus SAFR-032 equivalent or better than exposure to hydrogen peroxide. These results indicate efficacy of chlorine dioxide delivered through a stabilized chlorine dioxide product as a means of sterilization of peroxide- and UV-resistant spores.

  12. An evolutionary history of defensins: a role for copy number variation in maximizing host innate and adaptive immune responses.

    Directory of Open Access Journals (Sweden)

    Lee R Machado

    2015-03-01

    Full Text Available Defensins represent an evolutionary ancient family of antimicrobial peptides that play diverse roles in human health and disease. Defensins are cationic cysteine-containing multifunctional peptides predominantly expressed by epithelial cells or neutrophils. Defensins play a key role in host innate immune responses to infection and, in addition to their classically described role as antimicrobial peptides, have also been implicated in immune modulation, fertility, development and wound healing. Aberrant expression of defensins is important in a number of inflammatory diseases as well as modulating host immune responses to bacteria, unicellular pathogens and viruses. In parallel with their role in immunity, in other species, defensins have evolved alternative functions, including the control of coat color in dogs. Defensin genes reside in complex genomic regions that are prone to structural variations and some defensin family members exhibit copy number variation (CNV. Structural variations have mediated, and continue to influence, the diversification and expression of defensin family members. This review highlights the work currently being done to better understand the genomic architecture of the β-defensin locus. It evaluates current evidence linking defensin copy number variation to autoimmune disease (i.e. Crohn’s disease and psoriasis as well as the contribution CNV has in influencing immune responses to HIV infection.

  13. Analysis of Bacterial Drug Resistance%当前细菌抗药性探析

    Institute of Scientific and Technical Information of China (English)

    张建

    2014-01-01

    目的对当前细菌抗药性进行分析。方法对我院于2012年4月~2013年5月采集、分离1800株病原菌进行药物敏感性试验结果进行分析。结果在1800株病原菌中,革兰氏阴性菌1080株(60.00%),革兰氏阳性菌503株(27.94%),真菌217株(12.06%)。铜绿假单胞菌对各种常用抗生素均具有较强耐性,且三代与第四代头孢类抗生素病原菌抗药性不断增强。结论在抗生素临床应用中,应以病菌药敏试验结果为依据,选择病菌敏感性抗生素,才能提高治疗效果,降低致病菌抗药性。%Objective To analyze the drug resistance of bacteria. Methods In our hospital from 2012 April to 2013 May acquisition, isolated 1800 strains of pathogenic bacteria drug sensitivity test results. Results Among 1800 strains of pathogens, gram negative bacil i 1080 isolates (60%), gram positive bacil i 503 isolates (27.94%), 217 strains of fungi (12.06%). Pseudomonas aeruginosa has strong resistance to commonly used antibiotics, and the three and fourth generation cephalosporin antibiotic resistance of pathogens growing. Conclusion In the clinical application of antibiotics to bacteria, should be based on the drug sensitivity test, selection of antibiotic susceptibility of bacteria, can improve the treatment ef ect, reduce pathogenic bacteria resistance.

  14. Effects of sulfur dioxide on resistance to bacterial infection in mice

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay-Dupuis, E. (Hopital Claude Bernard, Paris, France); Bouley, G.; Blayo, M.C.

    1982-12-01

    Continuous exposure to approximately a 10-ppm concentration of sulfur dioxide for periods of up to 3 weeks reduced the resistance of female mice to infection by aerosol inoculation with Klebsiella pneumoniae. The mortality rate rose and survival time shortened in SO/sub 2/-exposed animals compared to controls. Insofar as these results can be extrapolated to humans, the SO/sub 2/ concentration used in this work is only found on certain industrial premises.

  15. Effects of nitric oxide on resistance to bacterial infection in mice

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay, E. (INSERM, Paris, France); Bouley, G.; Blayo, M.C.

    1981-06-01

    Continuous exposure to 2 ppM nitric oxide (NO) for as long as 4 wk did not reduce the resistance of male mice to infection by aerosol inoculation with Pasteurella multocida. In contrast, mortality was slightly enhanced and survival shortened in NO-exposed compared to control female mice; however, the importance of these small differences is uncertain. These results suggest only that male and famale mice did not react similarly to the infectious challenge after exposure to NO.

  16. Bacterial spore heat resistance correlated with water content, wet density, and protoplast/sporoplast volume ratio.

    Science.gov (United States)

    Beaman, T C; Greenamyre, J T; Corner, T R; Pankratz, H S; Gerhardt, P

    1982-05-01

    Five types of dormant Bacillus spores, between and within species, were selected representing a 600-fold range in moist-heat resistance determined as a D100 value. The wet and dry density and the solids and water content of the entire spore and isolated integument of each type were determined directly from gram masses of material, with correction for interstitial water. The ratio between the volume occupied by the protoplast (the structures bounded by the inner pericytoplasm membrane) and the volume occupied by the sporoplast (the structures bounded by the outer pericortex membrane) was calculated from measurements made on electron micrographs of medially thin-sectioned spores. Among the various spore types, an exponential increase in the heat resistance correlated directly with the wet density and inversely with the water content and with the protoplast/sporoplast volume ratio. Altogether with results supported a hypothesis that the extent of heat resistance is based in whole or in part on the extent of dehydration and diminution of the protoplast in the dormant spore, without implications about physiological mechanisms for attaining this state.

  17. Reversing bacterial resistance to antibiotics by phage-mediated delivery of dominant sensitive genes.

    Science.gov (United States)

    Edgar, Rotem; Friedman, Nir; Molshanski-Mor, Shahar; Qimron, Udi

    2012-02-01

    Pathogen resistance to antibiotics is a rapidly growing problem, leading to an urgent need for novel antimicrobial agents. Unfortunately, development of new antibiotics faces numerous obstacles, and a method that resensitizes pathogens to approved antibiotics therefore holds key advantages. We present a proof of principle for a system that restores antibiotic efficiency by reversing pathogen resistance. This system uses temperate phages to introduce, by lysogenization, the genes rpsL and gyrA conferring sensitivity in a dominant fashion to two antibiotics, streptomycin and nalidixic acid, respectively. Unique selective pressure is generated to enrich for bacteria that harbor the phages carrying the sensitizing constructs. This selection pressure is based on a toxic compound, tellurite, and therefore does not forfeit any antibiotic for the sensitization procedure. We further demonstrate a possible way of reducing undesirable recombination events by synthesizing dominant sensitive genes with major barriers to homologous recombination. Such synthesis does not significantly reduce the gene's sensitization ability. Unlike conventional bacteriophage therapy, the system does not rely on the phage's ability to kill pathogens in the infected host, but instead, on its ability to deliver genetic constructs into the bacteria and thus render them sensitive to antibiotics prior to host infection. We believe that transfer of the sensitizing cassette by the constructed phage will significantly enrich for antibiotic-treatable pathogens on hospital surfaces. Broad usage of the proposed system, in contrast to antibiotics and phage therapy, will potentially change the nature of nosocomial infections toward being more susceptible to antibiotics rather than more resistant.

  18. Quorum sensing system regulation on bacterial resistance%群体感应系统对细菌耐药的调控作用

    Institute of Scientific and Technical Information of China (English)

    朱艮苗; 杨维青

    2011-01-01

    Quorum sensing was a common mechanism that bacteria regulated the adapting ability of communities depending on cell density. Bacterial quorum sensing system regulated a number of specific functions,such as bacterial resistance-related traits. This paper reviewed the regulation of quorum sensing system on bacterial resistance-related traits.%群体感应是细菌依赖于细胞密度、调节群体适应能力的一种普遍机制.细菌群体感应系统调节许多特定的功能,如对细菌耐药相关性状的调节.本文就群体感应系统对细菌耐药相关性状的调控作用进行综述.

  19. Transgenic banana plants expressing Xanthomonas wilt resistance genes revealed a stable non-target bacterial colonization structure.

    Science.gov (United States)

    Nimusiima, Jean; Köberl, Martina; Tumuhairwe, John Baptist; Kubiriba, Jerome; Staver, Charles; Berg, Gabriele

    2015-12-10

    Africa is among the continents where the battle over genetically modified crops is currently being played out. The impact of GM in Africa could potentially be very positive. In Uganda, researchers have developed transgenic banana lines resistant to banana Xanthomonas wilt. The transgenic lines expressing hrap and pflp can provide a timely solution to the pandemic. However, the impact of the transgenes expression on non-target microorganisms has not yet been investigated. To study this effect, transgenic and control lines were grown under field conditions and their associated microbiome was investigated by 16S rRNA gene profiling combining amplicon sequencing and molecular fingerprinting. Three years after sucker planting, no statistically significant differences between transgenic lines and their non-modified predecessors were detected for their associated bacterial communities. The overall gammaproteobacterial rhizosphere microbiome was highly dominated by Xanthomonadales, while Pseudomonadales and Enterobacteriales were accumulated in the pseudostem. Shannon indices revealed much higher diversity in the rhizosphere than in the pseudostem endosphere. However, the expression of the transgenes did not result in changes in the diversity of Gammaproteobacteria, the closest relatives of the target pathogen. In this field experiment, the expression of the resistance genes appears to have no consequences for non-target rhizobacteria and endophytes.

  20. Fine mapping of the rice bacterial blight resistance gene Xa-4 and its co-segregation marker

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An F2 population developed from the Xa-4 near isogenic lines,IR24 and IRBB4,was used for fine mapping of the rice bacterial blight resistance gene,Xa-4.Some restriction fragment length polymorphism (RFLP) markers on the high-density map constructed by Harushima et al.and the amplified DNA fragments homologous to the conserved domains of plant disease resistance (R) genes were used to construct the genetic linkage map around the gene Xa-4 by scoring susceptible individuals in the population.Xa-4 was mapped between the RFLP marker G181 and the polymerase chain reaction (PCR) marker M55.The R gene homologous fragment marker RS13 was found co-segregating with Xa-4 by analyzing all the plants in the population.This result opened an approach to map-based cloning of this gene,and marker RS13 can be applied to molecular marker-assisted selection of Xa-4 in rice breeding programs.

  1. Antibacterial action of doped CoFe{sub 2}O{sub 4} nanocrystals on multidrug resistant bacterial strains

    Energy Technology Data Exchange (ETDEWEB)

    Velho-Pereira, S.; Noronha, A.; Mathias, A.; Zakane, R.; Naik, V.; Naik, P. [Department of Biotechnology, St. Xavier' s College, Goa (India); Salker, A.V. [Department of Chemistry, Goa University, Goa (India); Naik, S.R., E-mail: srnaik19@gmail.com [Department of Chemistry, St. Xavier' s College, Goa (India)

    2015-07-01

    The bactericidal effect of pristine and doped cobalt ferrite nanoparticles has been evaluated against multiple drug resistant clinical strains by assessing the number of colony-forming units (CFU). Monophasic polycrystalline ferrites have been prepared by the malate–glycolate sol–gel autocombustion method as confirmed by the X-ray diffraction study. Various changes occurring during the preparative stages have been demonstrated using TG–DTA analysis which is well complemented by the FTIR spectroscopy. The antibacterial studies carried out demonstrate a bactericidal effect of the nanoparticles wherein the number of CFU has been found to decrease with doping. Cellular distortions have been revealed through SEM. Variation in the number of CFU with dopant type has also been reported herein. - Graphical abstract: Antibacterial action of doped cobalt ferrites resulting in the lyses of multi-drug resistant bacterial strains. - Highlights: • The paper reports an antibacterial study of rare earth doped cobalt ferrite nanoparticles. • Monophasic compounds have been prepared by the sol–gel autocombustion method. • Bactericidal property has been evaluated based on the number of colony forming units. • Variation in bactericidal action with respect to the dopant type has been observed. • Cellular distortions resulting in cell lysis are confirmed from the SEM images.

  2. Development of a broad spectrum polymer-released antimicrobial coating for the prevention of resistant strain bacterial infections.

    Science.gov (United States)

    Sinclair, K D; Pham, T X; Farnsworth, R W; Williams, D L; Loc-Carrillo, C; Horne, L A; Ingebretsen, S H; Bloebaum, R D

    2012-10-01

    More than 400,000 primary hip and knee replacement surgeries are performed each year in the United States. From these procedures, approximately 0.5-3% will become infected and when considering revision surgeries, this rate has been found to increase significantly. Antibiotic-resistant bacterial infections are a growing problem in patient care. This in vitro research investigated the antimicrobial potential of the polymer released, broad spectrum, Cationic Steroidal Antimicrobial-13 (CSA-13) for challenges against 5 × 10(8) colony forming units (CFU) of methicillin-resistant Staphylococcus aureus (MRSA). It was hypothesized that a weight-to-weight (w/w) concentration of 18% CSA-13 in silicone would exhibit potent bactericidal potential when used as a controlled release device coating. When incorporated into a polymeric device coating, the 18% (w/w) broad-spectrum polymer released CSA-13 antimicrobial eliminated 5 × 10(8) CFU of MRSA within 8 h. In the future, these results will be utilized to develop a sheep model to assess CSA-13 for the prevention of perioperative device-related infections in vivo.

  3. Mixed biofilm formation by Shiga toxin-producing Escherichia coli and Salmonella enterica serovar typhimurium enhanced bacterial resistance to sanitization due to extracellular polymeric substances

    Science.gov (United States)

    Shiga toxin–producing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium are important foodborne pathogens capable of forming single-species biofilms or coexisting in multispecies biofilm communities. Bacterial biofilm cells are usually more resistant to sanitization than their pla...

  4. Genomic selection models double the accuracy of predicted breeding values for bacterial cold water disease resistance compared to a traditional pedigree-based model in rainbow trout aquaculture

    Science.gov (United States)

    Previously we have shown that bacterial cold water disease (BCWD) resistance in rainbow trout can be improved using traditional family-based selection, but progress has been limited to exploiting only between-family genetic variation. Genomic selection (GS) is a new alternative enabling exploitation...

  5. Genome-enabled selection doubles the accuracy of predicted breeding values for bacterial cold water disease resistance compared to traditional family-based selection in rainbow trout aquaculture

    Science.gov (United States)

    We have shown previously that bacterial cold water disease (BCWD) resistance in rainbow trout can be improved using traditional family-based selection, but progress has been limited to exploiting only between-family genetic variation. Genomic selection (GS) is a new alternative enabling exploitation...

  6. Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.)

    Science.gov (United States)

    Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce ge...

  7. The Analysis Of Antibiotic Consumption And Bacterial Resistance As An Indicator Of Their Proper Use At The Urology Department In The Health Centre “Studenica” Kraljevo

    Directory of Open Access Journals (Sweden)

    Bukonjić Andriana

    2015-06-01

    Full Text Available The objective of the study was to analyze antibiotic consumption and determine bacterial resistance rates as an indicator of the rational utilization of this drug group at the urology department in the Health Centre “Studenica” Kraljevo.

  8. Nano-layered magnesium fluoride reservoirs on biomaterial surfaces strengthen polymorphonuclear leukocyte resistance to bacterial pathogens.

    Science.gov (United States)

    Guo, Geyong; Zhou, Huaijuan; Wang, Qiaojie; Wang, Jiaxing; Tan, Jiaqi; Li, Jinhua; Jin, Ping; Shen, Hao

    2017-01-05

    Biomaterial-related bacterial infections cause patient suffering, mortality and extended periods of hospitalization, imposing a substantial burden on medical systems. In this context, understanding of nanomaterials-bacteria-cells interactions is of both fundamental and clinical significance. Herein, nano-MgF2 films were deposited on titanium substrate via magnetron sputtering. Using this platform, the antibacterial behavior and mechanism of the nano-MgF2 films were investigated in vitro and in vivo. It was found that, for S. aureus (CA-MRSA, USA300) and S. epidermidis (RP62A), the nano-MgF2 films possessed excellent anti-biofilm activity, but poor anti-planktonic bacteria activity in vitro. Nevertheless, both the traditional SD rat osteomyelitis model and the novel stably luminescent mouse infection model demonstrated that nano-MgF2 films exerted superior anti-infection effect in vivo, which cannot be completely explained by the antibacterial activity of the nanomaterial itself. Further, using polymorphonuclear leukocytes (PMNs), the critical immune cells of innate immunity, a complementary investigation of MgF2-bacteria-PMNs co-culturing revealed that the nano-MgF2 films improved the antibacterial effect of PMNs through enhancing their phagocytosis and stability. To our knowledge, this is the first time of exploring the antimicrobial mechanism of nano-MgF2 from the perspective of innate immunity both in vitro and in vivo. Based on the research results, a plausible mechanism is put forward for the predominant antibacterial effect of nano-MgF2in vivo, which may originate from the indirect immune enhancement effect of nano-MgF2 films. In summary, this study of surface antibacterial design using MgF2 nanolayer is a meaningful attempt, which can promote the host innate immune response to bacterial pathogens. This may give us a new understanding towards the antibacterial behavior and mechanism of nano-MgF2 films and pave the way towards their clinical applications.

  9. An Oxidoreductase AioE is Responsible for Bacterial Arsenite Oxidation and Resistance

    Science.gov (United States)

    Wang, Qian; Han, Yushan; Shi, Kaixiang; Fan, Xia; Wang, Lu; Li, Mingshun; Wang, Gejiao

    2017-01-01

    Previously, we found that arsenite (AsIII) oxidation could improve the generation of ATP/NADH to support the growth of Agrobacterium tumefaciens GW4. In this study, we found that aioE is induced by AsIII and located in the arsenic island near the AsIII oxidase genes aioBA and co-transcripted with the arsenic resistant genes arsR1-arsC1-arsC2-acr3-1. AioE belongs to TrkA family corresponding the electron transport function with the generation of NADH and H+. An aioE in-frame deletion strain showed a null AsIII oxidation and a reduced AsIII resistance, while a cytC mutant only reduced AsIII oxidation efficiency. With AsIII, aioE was directly related to the increase of NADH, while cytC was essential for ATP generation. In addition, cyclic voltammetry analysis showed that the redox potential (ORP) of AioBA and AioE were +0.297 mV vs. NHE and +0.255 mV vs. NHE, respectively. The ORP gradient is AioBA > AioE > CytC (+0.217 ~ +0.251 mV vs. NHE), which infers that electron may transfer from AioBA to CytC via AioE. The results indicate that AioE may act as a novel AsIII oxidation electron transporter associated with NADH generation. Since AsIII oxidation contributes AsIII detoxification, the essential of AioE for AsIII resistance is also reasonable. PMID:28128323

  10. Survival and evolution of a large multidrug resistance plasmid in new clinical bacterial hosts

    DEFF Research Database (Denmark)

    Porse, Andreas; Schønning, Kristian; Munck, Christian;

    2016-01-01

    of these plasmids within pathogenic hosts are poorly understood. Here we study plasmid-host adaptations following transfer of a 73 kb conjugative multidrug resistance plasmid to naïve clinical isolates of Klebsiella pneumoniae and Escherichia coli We use experimental evolution, mathematical modelling and population...... of costly regions from the plasmid backbone, effectively expanding the host-range of the plasmid. Although these adaptations were also beneficial to plasmid persistence in a naïve K. pneumoniae host, they were never observed in this species, indicating that differential evolvability can limit opportunities...

  11. In Vivo Evolution of Bacterial Resistance in Two Cases of Enterobacter aerogenes Infections during Treatment with Imipenem.

    Science.gov (United States)

    Philippe, Nadège; Maigre, Laure; Santini, Sébastien; Pinet, Elizabeth; Claverie, Jean-Michel; Davin-Régli, Anne-Véronique; Pagès, Jean-Marie; Masi, Muriel

    2015-01-01

    Infections caused by multidrug resistant (MDR) bacteria are a major concern worldwide. Changes in membrane permeability, including decreased influx and/or increased efflux of antibiotics, are known as key contributors of bacterial MDR. Therefore, it is of critical importance to understand molecular mechanisms that link membrane permeability to MDR in order to design new antimicrobial strategies. In this work, we describe genotype-phenotype correlations in Enterobacter aerogenes, a clinically problematic and antibiotic resistant bacterium. To do this, series of clinical isolates have been periodically collected from two patients during chemotherapy with imipenem. The isolates exhibited different levels of resistance towards multiple classes of antibiotics, consistently with the presence or the absence of porins and efflux pumps. Transport assays were used to characterize membrane permeability defects. Simultaneous genome-wide analysis allowed the identification of putative mutations responsible for MDR. The genome of the imipenem-susceptible isolate G7 was sequenced to closure and used as a reference for comparative genomics. This approach uncovered several loci that were specifically mutated in MDR isolates and whose products are known to control membrane permeability. These were omp35 and omp36, encoding the two major porins; rob, encoding a global AraC-type transcriptional activator; cpxA, phoQ and pmrB, encoding sensor kinases of the CpxRA, PhoPQ and PmrAB two-component regulatory systems, respectively. This report provides a comprehensive analysis of membrane alterations relative to mutational steps in the evolution of MDR of a recognized nosocomial pathogen.

  12. In Vivo Evolution of Bacterial Resistance in Two Cases of Enterobacter aerogenes Infections during Treatment with Imipenem.

    Directory of Open Access Journals (Sweden)

    Nadège Philippe

    Full Text Available Infections caused by multidrug resistant (MDR bacteria are a major concern worldwide. Changes in membrane permeability, including decreased influx and/or increased efflux of antibiotics, are known as key contributors of bacterial MDR. Therefore, it is of critical importance to understand molecular mechanisms that link membrane permeability to MDR in order to design new antimicrobial strategies. In this work, we describe genotype-phenotype correlations in Enterobacter aerogenes, a clinically problematic and antibiotic resistant bacterium. To do this, series of clinical isolates have been periodically collected from two patients during chemotherapy with imipenem. The isolates exhibited different levels of resistance towards multiple classes of antibiotics, consistently with the presence or the absence of porins and efflux pumps. Transport assays were used to characterize membrane permeability defects. Simultaneous genome-wide analysis allowed the identification of putative mutations responsible for MDR. The genome of the imipenem-susceptible isolate G7 was sequenced to closure and used as a reference for comparative genomics. This approach uncovered several loci that were specifically mutated in MDR isolates and whose products are known to control membrane permeability. These were omp35 and omp36, encoding the two major porins; rob, encoding a global AraC-type transcriptional activator; cpxA, phoQ and pmrB, encoding sensor kinases of the CpxRA, PhoPQ and PmrAB two-component regulatory systems, respectively. This report provides a comprehensive analysis of membrane alterations relative to mutational steps in the evolution of MDR of a recognized nosocomial pathogen.

  13. Chlor-alkali plant contamination of Aussa River sediments induced a large Hg-resistant bacterial community

    Science.gov (United States)

    Baldi, Franco; Marchetto, Davide; Gallo, Michele; Fani, Renato; Maida, Isabel; Covelli, Stefano; Fajon, Vesna; Zizek, Suzana; Hines, Mark; Horvat, Milena

    2012-11-01

    A closed chlor-alkali plant (CAP) discharged Hg for decades into the Aussa River, which flows into Marano Lagoon, resulting in the large-scale pollution of the lagoon. In order to get information on the role of bacteria as mercury detoxifying agents, analyses of anions in the superficial part (0-1 cm) of sediments were conducted at four stations in the Aussa River. In addition, measurements of biopolymeric carbon (BPC) as a sum of the carbon equivalent of proteins (PRT), lipids (LIP), and carbohydrates (CHO) were performed to correlate with bacterial biomass such as the number of aerobic heterotrophic cultivable bacteria and their percentage of Hg-resistant bacteria. All these parameters were used to assess the bioavailable Hg fraction in sediments and the potential detoxification activity of bacteria. In addition, fifteen isolates were characterized by a combination of molecular techniques, which permitted their assignment into six different genera. Four out of fifteen were Gram negative with two strains of Stenotrophomonas maltophilia, one Enterobacter sp., and one strain of Brevibacterium frigoritolerans. The remaining strains (11) were Gram positive belonging to the genera Bacillus and Staphylococcus. We found merA genes in only a few isolates. Mercury volatilization from added HgCl2 and the presence of plasmids with the merA gene were also used to confirm Hg reductase activity. We found the highest number of aerobic heterotrophic Hg-resistant bacteria (one order magnitude higher) and the highest number of Hg-resistant species (11 species out of 15) at the confluence of the River Aussa and Banduzzi's channel, which transport Hg from the CAP, suggesting that Hg is strongly detoxified [reduced to Hg(0)] at this location.

  14. Pyrosequencing the Bemisia tabaci transcriptome reveals a highly diverse bacterial community and a robust system for insecticide resistance.

    Directory of Open Access Journals (Sweden)

    Wen Xie

    Full Text Available BACKGROUND: Bemisia tabaci (Gennadius is a phloem-feeding insect poised to become one of the major insect pests in open field and greenhouse production systems throughout the world. The high level of resistance to insecticides is a main factor that hinders continued use of insecticides for suppression of B. tabaci. Despite its prevalence, little is known about B. tabaci at the genome level. To fill this gap, an invasive B. tabaci B biotype was subjected to pyrosequencing-based transcriptome analysis to identify genes and gene networks putatively involved in various physiological and toxicological processes. METHODOLOGY AND PRINCIPAL FINDINGS: Using Roche 454 pyrosequencing, 857,205 reads containing approximately 340 megabases were obtained from the B. tabaci transcriptome. De novo assembly generated 178,669 unigenes including 30,980 from insects, 17,881 from bacteria, and 129,808 from the nohit. A total of 50,835 (28.45% unigenes showed similarity to the non-redundant database in GenBank with a cut-off E-value of 10-5. Among them, 40,611 unigenes were assigned to one or more GO terms and 6,917 unigenes were assigned to 288 known pathways. De novo metatranscriptome analysis revealed highly diverse bacterial symbionts in B. tabaci, and demonstrated the host-symbiont cooperation in amino acid production. In-depth transcriptome analysis indentified putative molecular markers, and genes potentially involved in insecticide resistance and nutrient digestion. The utility of this transcriptome was validated by a thiamethoxam resistance study, in which annotated cytochrome P450 genes were significantly overexpressed in the resistant B. tabaci in comparison to its susceptible counterparts. CONCLUSIONS: This transcriptome/metatranscriptome analysis sheds light on the molecular understanding of symbiosis and insecticide resistance in an agriculturally important phloem-feeding insect pest, and lays the foundation for future functional genomics research of the

  15. Ectopic expression of Hrf1 enhances bacterial resistance via regulation of diterpene phytoalexins, silicon and reactive oxygen species burst in rice.

    Directory of Open Access Journals (Sweden)

    Wenqi Li

    Full Text Available Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo, Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpin(Xoo protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H(2O(2 concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM and energy-dispersive X-ray spectrometer (EDS. Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H(2O(2, silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens.

  16. Ectopic Expression of Hrf1 Enhances Bacterial Resistance via Regulation of Diterpene Phytoalexins, Silicon and Reactive Oxygen Species Burst in Rice

    Science.gov (United States)

    Zhong, Weigong; Yang, Jie; Okada, Kazunori; Yamane, Hisakazu; Zhang, Lei; Wang, Guang; Wang, Dong; Xiao, Shanshan; Chang, Shanshan; Qian, Guoliang; Liu, Fengquan

    2012-01-01

    Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo), Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpinXoo protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H2O2) concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H2O2, silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens. PMID:22970151

  17. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins.

    Directory of Open Access Journals (Sweden)

    Felix Dempwolff

    2016-06-01

    Full Text Available Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro-and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds.

  18. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie) Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins

    Science.gov (United States)

    Dempwolff, Felix; Schmidt, Felix K.; Hervás, Ana B.; Stroh, Alex; Rösch, Thomas C.; Riese, Cornelius N.; Dersch, Simon; Heimerl, Thomas; Lucena, Daniella; Hülsbusch, Nikola; Stuermer, Claudia A. O.; Takeshita, Norio; Fischer, Reinhard; Graumann, Peter L.

    2016-01-01

    Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro—and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds. PMID:27362352

  19. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie) Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins.

    Science.gov (United States)

    Dempwolff, Felix; Schmidt, Felix K; Hervás, Ana B; Stroh, Alex; Rösch, Thomas C; Riese, Cornelius N; Dersch, Simon; Heimerl, Thomas; Lucena, Daniella; Hülsbusch, Nikola; Stuermer, Claudia A O; Takeshita, Norio; Fischer, Reinhard; Eckhardt, Bruno; Graumann, Peter L

    2016-06-01

    Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro-and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds.

  20. Antibacterial and antiviral roles of a fish β-defensin expressed both in pituitary and testis.

    Directory of Open Access Journals (Sweden)

    Jun-Yan Jin

    Full Text Available Defensins are a group of cationic peptides that exhibit broad-spectrum antimicrobial activity. In this study, we cloned and characterized a β-defensin from pituitary cDNA library of a protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides. Interestingly, the β-defensin was shown to be dominantly expressed in pituitary and testis by RT-PCR and Western blot analysis, and its transcript level is significantly upregulated in reproduction organs from intersexual gonad to testis during the natural and artificial sex reversal. Promoter sequence and the responsible activity region analyses revealed the pituitary-specific POU1F1a transcription binding site and testis-specific SRY responsible site, and demonstrated that the pituitary-specific POU1F1a transcription binding site that locates between -180 and -208 bp is the major responsible region of grouper β-defensin promoter activity. Immunofluorescence localization observed its pituicyte expression in pituitary and spermatogonic cell expression in testis. Moreover, both in vitro antibacterial activity assay of the recombinant β-defensin and in vivo embryo microinjection of the β-defensin mRNA were shown to be effective in killing gram-negative bacteria. And, its antiviral role was also demonstrated in EPC cells transfected with the β-defensin construct. Additionally, the antibacterial activity was sensitive to concentrations of Na(+, K(+, Ca(2+ and Mg(2+. The above intriguing findings strongly suggest that the fish β-defensin might play significant roles in both innate immunity defense and reproduction endocrine regulation.

  1. One-day workflow scheme for bacterial pathogen detection and antimicrobial resistance testing from blood cultures.

    Science.gov (United States)

    Hansen, Wendy L J; Beuving, Judith; Verbon, Annelies; Wolffs, Petra F G

    2012-07-09

    Bloodstream infections are associated with high mortality rates because of the probable manifestation of sepsis, severe sepsis and septic shock(1). Therefore, rapid administration of adequate antibiotic therapy is of foremost importance in the treatment of bloodstream infections. The critical element in this process is timing, heavily dependent on the results of bacterial identification and antibiotic susceptibility testing. Both of these parameters are routinely obtained by culture-based testing, which is time-consuming and takes on average 24-48 hours(2, 4). The aim of the study was to develop DNA-based assays for rapid identification of bloodstream infections, as well as rapid antimicrobial susceptibility testing. The first assay is a eubacterial 16S rDNA-based real-time PCR assay complemented with species- or genus-specific probes(5). Using these probes, Gram-negative bacteria including Pseudomonas spp., Pseudomonas aeruginosa and Escherichia coli as well as Gram-positive bacteria including Staphylococcus spp., Staphylococcus aureus, Enterococcus spp., Streptococcus spp., and Streptococcus pneumoniae could be distinguished. Using this multiprobe assay, a first identification of the causative micro-organism was given after 2 h. Secondly, we developed a semi-molecular assay for antibiotic susceptibility testing of S. aureus, Enterococcus spp. and (facultative) aerobe Gram-negative rods(6). This assay was based on a study in which PCR was used to measure the growth of bacteria(7). Bacteria harvested directly from blood cultures are incubated for 6 h with a selection of antibiotics, and following a Sybr Green-based real-time PCR assay determines inhibition of growth. The combination of these two methods could direct the choice of a suitable antibiotic therapy on the same day (Figure 1). In conclusion, molecular analysis of both identification and antibiotic susceptibility offers a faster alternative for pathogen detection and could improve the diagnosis of

  2. Correlation between plasma component levels of cultured fish and resistance to bacterial infection

    Science.gov (United States)

    Maita, M.; Satoh, K.-I.; Fukuda, Y.; Lee, H.-K.; Winton, J.R.; Okamoto, N.

    1998-01-01

    Mortalities of yellowtail Seriola quinqueradiata artificially infected with Lactococcus garvieae and of rainbow trout Oncorhynchus mykiss artificially infected with Vibrio anguillarum were compared with the levels of plasma components measured prior to challenge. The levels of plasma total cholesterol, free cholesterol and phospholipid of fish surviving infection were significantly higher in both yellowtail and rainbow trout than those of fish which died during the challenge test. Mortality of yellowtail with plasma total cholesterol levels lower than 250 mg/100 ml was significantly higher than that of fish which had cholesterol levels higher than 275 mg/100 ml (p < 0.05). Rainbow trout whose cholesterol was lower than 520 mg/100 ml suffered a significantly higher mortality due to vibriosis than fish having cholesterol levels higher than 560 mg/100 ml (p < 0.005). These results indicate that low levels of plasma lipid components may be an indicator of lowered disease resistance in cultured fish.

  3. Bacterial resistance to ultraviolet irradiation under anaerobiosis: implications for pre-phanerozoic evolution.

    Science.gov (United States)

    Rambler, M B; Margulis, L

    1980-11-07

    The concept that low concentrations of atmospheric oxygen and consequent unattenuated ultraviolet irradiation limited the emergence of Phanerozoic life, the Berkner-Marshall hypothesis, is no longer tenable. Anaerobic bacteria, which probably evolved far earlier than Metazoa, were irradiated in a special chamber under strictly anaerobic conditions. Both intrinsic resistance and photoreactivation by visible light were discovered in obligately and facultatively anaeroboc microbes. Atmospheric scientists have shown that small amounts of oxygen would have limied pre-Phanerozoic surface ultraviolet irradiation to fluxes well below those used in the anaerobic experiments described. Since adequate ultraviolet protection mechanisms evolved early, the late Proterozoic appearance of Metazoa probably was not related to high fluxes of solar ultraviolet radiation.

  4. Synergistic antibacterial effect of apigenin with β-lactam antibiotics and modulation of bacterial resistance by a possible membrane effect against methicillin resistant Staphylococcus aureus.

    Science.gov (United States)

    Akilandeswari, K; Ruckmani, K

    2016-12-30

    membrane of this strain. From these results, it can be concluded that apigenin has the synergistic effect with ampicillin and ceftriaxone to reverse bacterial resistance against MRSA.

  5. Structural characterization of the cyclic cystine ladder motif of θ-defensins.

    Science.gov (United States)

    Conibear, Anne C; Rosengren, K Johan; Harvey, Peta J; Craik, David J

    2012-12-04

    The θ-defensins are, to date, the only known ribosomally synthesized cyclic peptides in mammals, and they have promising antimicrobial bioactivities. The characteristic structural motif of the θ-defensins is the cyclic cystine ladder, comprising a cyclic peptide backbone and three parallel disulfide bonds. In contrast to the cyclic cystine knot, which characterizes the plant cyclotides, the cyclic cystine ladder has not been as well described as a structural motif. Here we report the solution structures and nuclear magnetic resonance relaxation properties in aqueous solution of three representative θ-defensins from different species. Our data suggest that the θ-defensins are more rigid and structurally defined than previously thought. In addition, all three θ-defensins were found to self-associate in aqueous solution in a concentration-dependent and reversible manner, a property that might have a role in their mechanism of action. The structural definition of the θ-defensins and the cyclic cystine ladder will help to guide exploitation of these molecules as structural frameworks for the design of peptide drugs.

  6. Evidence that the role of plant defensins in radish defense responses is independent of salicylic acid.

    Science.gov (United States)

    Terras, F R; Penninckx, I A; Goderis, I J; Broekaert, W F

    1998-09-01

    Radish leaves contain two homologous 5-kDa plant defensins which accumulate systemically upon infection by fungal pathogens (F.R.G. Terras et al., 1995, Plant Cell 7: 573-588). Here we report on the molecular cloning of the cDNAs encoding the two pathogen-inducible plant defensin isoforms from radish (Raphanus sativus L.) leaves. Tissue-print and whole-leaf electroblot immunostaining showed that the plant defensin peptides not only accumulate at high levels at or immediately around the infection sites in leaves inoculated with Alternaria brassicicola, but also accumulate in healthy tissue further away from the infection sites and in non-infected leaves from injected plants. Gel blot analysis of RNA confirmed that expression of plant defensin genes is systemically triggered upon fungal infection whereas radish PR-1 gene expression is only activated locally. In contrast to the radish PR-1 gene(s), expression of the radish plant defensin genes was not induced by external application of salicylic acid. Activation of the plant defensin genes, but not that of PR-1 genes, occurred upon treatment with methyl jasmonate, ethylene and paraquat.

  7. Mercury resistance in bacterial strains isolated from tailing ponds in a gold mining area near El Callao (Bolívar State, Venezuela).

    Science.gov (United States)

    Ball, María Mercedes; Carrero, Pablo; Castro, David; Yarzábal, Luis Andrés

    2007-02-01

    Bacterial resistance to mercury (Hg) was investigated in strains isolated from Hg-contaminated tailing ponds located in the gold mining area of El Callao (Bolívar State, Venezuela). High frequencies of resistance were detected to both inorganic-Hg and organomercurials among these strains. A broad range of resistance levels was observed when determining minimal inhibitory concentrations of Hg(2+). Some strains were able to grow in liquid medium containing 25 muM: Hg(2+), whereas others grew at 300 muM: Hg(2+). Of 190 Hg-resistant strains tested, 58.2% were additionally shown to be resistant to ampicillin (40 mg/L), 33.3% to chloramphenicol (30 mg/L), 24.9% to streptomycin (30 mg/L), 23.3% to tetracycline (30 mg/L), and 1.6% to kanamycin (30 mg/L). Furthermore, we found that 20% of the Hg-resistant strains were simultaneously resistant to as many as four of these antibiotics, at the concentrations tested. The presence of large plasmids in 62.9% of 53 Hg-resistant strains screened prompted us to investigate the horizontal transfer of resistance determinants. Mating experiments were performed using Escherichia coli and Pseudomonas aeruginosa as recipient strains. The results obtained confirmed that indigenous Hg-resistant bacteria colonizing the tailing ponds can effectively transfer the phenotype to potentially pathogenic species.

  8. Mixed biofilm formation by Shiga toxin-producing Escherichia coli and Salmonella enterica serovar Typhimurium enhanced bacterial resistance to sanitization due to extracellular polymeric substances.

    Science.gov (United States)

    Wang, Rong; Kalchayanand, Norasak; Schmidt, John W; Harhay, Dayna M

    2013-09-01

    Shiga toxin-producing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium are important foodborne pathogens capable of forming single-species biofilms or coexisting in multispecies biofilm communities. Bacterial biofilm cells are usually more resistant to sanitization than their planktonic counterparts, so these foodborne pathogens in biofilms pose a serious food safety concern. We investigated how the coexistence of E. coli O157:H7 and Salmonella Typhimurium strains would affect bacterial planktonic growth competition and mixed biofilm composition. Furthermore, we also investigated how mixed biofilm formation would affect bacterial resistance to common sanitizers. Salmonella Typhimurium strains were able to outcompete E. coli strains in the planktonic growth phase; however, mixed biofilm development was highly dependent upon companion strain properties in terms of the expression of bacterial extracellular polymeric substances (EPS), including curli fimbriae and exopolysaccharide cellulose. The EPS-producing strains with higher biofilm-forming abilities were able to establish themselves in mixed biofilms more efficiently. In comparison to single-strain biofilms, Salmonella or E. coli strains with negative EPS expression obtained significantly enhanced resistance to sanitization by forming mixed biofilms with an EPS-producing companion strain of the other species. These observations indicate that the bacterial EPS components not only enhance the sanitizer resistance of the EPS-producing strains but also render protections to their companion strains, regardless of species, in mixed biofilms. Our study highlights the potential risk of cross-contamination by multispecies biofilms in food safety and the need for increased attention to proper sanitization practices in food processing facilities.

  9. Rat Cardiomyocytes Express a Classical Epithelial Beta-Defensin

    Directory of Open Access Journals (Sweden)

    Annika Linde

    2008-01-01

    Full Text Available Beta-defensins (BDs are classical epithelial antimicrobial peptides of immediate importance in innate host defense. Since recent studies have suggested that certain BDs are also expressed in non-traditional tissues, including whole heart homogenate and because effector molecules of innate immunity and inflammation can influence the development of certain cardiovascular disease processes, we hypothesized that BDs are produced by cardiomyocytes as a local measure of cardioprotection against danger signals. Here we report that at least one rat beta-defensin, rBD1, is expressed constitutively in cardiomyocytes specifically isolated using position-ablation-laser-microdissection (P.A.L.M. Microlaser Technologies. RT-PCR analysis showed expression of a single 318 bp transcript in adult rat heart (laser-excised cardiomyocytes and H9c2 cells (neonatal rat heart myoblasts. Moreover, the full length cDNA of rBD1 was established and translated into a putative peptide with 69 amino acid residues. The predicted amino acid sequence of the adult rat cardiac BD-1 peptide displayed 99% identity with the previously reported renal rBD1 and 88, 53, 53 and 50% identity with mouse, human, gorilla and rhesus monkey BD1 respectively. Furthermore, structural analysis of the cardiac rBD1 showed the classical six-cysteine conserved motif of the BD family with an alpha-helix and three beta-sheets. Additionally, rBD1 displayed a significantly greater number of amphoteric residues than any of the human analogs, indicating a strong pH functional dependence in the rat. We suggest that rBD1, which was initially believed to be a specific epithelium-derived peptide, may be also involved in local cardiac innate immune defense mechanisms.

  10. Genetic transformation of Nannochloropsis oculata with a bacterial phleomycin resistance gene as dominant selective marker

    Science.gov (United States)

    Ma, Xiaolei; Pan, Kehou; Zhang, Lin; Zhu, Baohua; Yang, Guanpin; Zhang, Xiangyang

    2016-04-01

    The gene ble from Streptoalloteichus hindustanus is widely used as a selective antibiotic marker. It can control the phleomycin resistance, and significantly increase the tolerance of hosts to zeocin. The unicellular marine microalga Nannochloropsis oculata is extremely sensitive to zeocin. We selected ble as the selective marker for the genetic transformation of N. oculata. After the algal cells at a density of 2×107 cells mL-1 was digested with 4% hemicellulase and 2% driselase for 1 h, the protoplasts accounted for 90% of the total. The ble was placed at the downstream of promoter HSP70A-RUBS2 isolated from Chlamydomonas reinhardtii, yielding a recombinant expression construct pMS188. The construct was transferred into the protoplasts through electroporation (1 kV, 15 μS). The transformed protoplasts were cultured in fresh f/2 liquid medium, and selected on solid f/2 medium supplemented with 500 ng mL-1 zeocin. The PCR result proved that ble existed in the transformants. Three transformants had been cultured for at least 5 generations without losing ble. Southern blotting analysis showed that the ble has been integrated into the genome of N. oculata. The ble will serve as a new dominant selective marker in genetic engineering N. oculata.

  11. Multidrug-resistant Escherichia coli soft tissue infection investigated with bacterial whole genome sequencing

    Science.gov (United States)

    Buchanan, Ruaridh; Stoesser, Nicole; Crook, Derrick; Bowler, Ian C J W

    2014-01-01

    A 45-year-old man with dilated cardiomyopathy presented with acute leg pain and erythema suggestive of necrotising fasciitis. Initial surgical exploration revealed no necrosis and treatment for a soft tissue infection was started. Blood and tissue cultures unexpectedly grew a Gram-negative bacillus, subsequently identified by an automated broth microdilution phenotyping system as an extended-spectrum β-lactamase producing Escherichia coli. The patient was treated with a 3-week course of antibiotics (ertapenem followed by ciprofloxacin) and debridement for small areas of necrosis, followed by skin grafting. The presence of E. coli triggered investigation of both host and pathogen. The patient was found to have previously undiagnosed liver disease, a risk factor for E. coli soft tissue infection. Whole genome sequencing of isolates from all specimens confirmed they were clonal, of sequence type ST131 and associated with a likely plasmid-associated AmpC (CMY-2), several other resistance genes and a number of virulence factors. PMID:25331151

  12. A bacterial artificial chromosome library for soybean PI 437654 and identification of clones associated with cyst nematode resistance.

    Science.gov (United States)

    Tomkins, J P; Mahalingam, R; Smith, H; Goicoechea, J L; Knap, H T; Wing, R A

    1999-09-01

    We have constructed a soybean bacterial artificial chromosome (BAC) library using the plant introduction (PI) 437654. The library contains 73 728 clones stored in 192 384-well microtiter plates. A random sampling of 230 BACs indicated an average insert size of 136 kb with a range of 20 to 325 kb, and less than 4% of the clones do not contain inserts. Ninety percent of BAC clones in the library have an average insert size greater than 100 kb. Based on a genome size of 1115 Mb, library coverage is 9 haploid genome equivalents. Screening the BAC library colony filters with cpDNA sequences showed that contamination of the genomic library with chloroplast clones was low (1.85%). Library screening with three genomic RFLP probes linked to soybean cyst nematode (SCN) resistance genes resulted in an average of 18 hits per probe (range 7 to 30). Two separate pools of forward and reverse suppression subtractive cDNAs obtained from SCN-infected and uninfected roots of PI437654 were hybridized to the BAC library filters. The 488 BACs identified from positive signals were fingerprinted and analyzed using FPC software (version 4.0) resulting in 85 different contigs. Contigs were grouped and analyzed in three categories: (1) contigs of BAC clones which hybridized to forward subtracted cDNAs, (2) contigs of BAC clones which hybridized to reverse subtracted cDNAs, and (3) contigs of BAC clones which hybridized to both forward and reverse subtracted cDNAs. This protocol provides an estimate of the number of genomic regions involved in early resistance response to a pathogenic attack.

  13. Infectious prosthetic hip joint loosening: bacterial species involved in its aetiology and their antibiotic resistance profiles against antibiotics recommended for the therapy of implant-associated infections.

    Science.gov (United States)

    Bogut, Agnieszka; Niedźwiadek, Justyna; Strzelec-Nowak, Dagmara; Blacha, Jan; Mazurkiewicz, Tomasz; Marczyński, Wojciech; Kozioł-Montewka, Maria

    2014-04-01

    Reliable microbiological diagnosis along with surgery and prolonged antibiotic therapy are key elements in the management of prosthetic-joint infections (PJIs). The purpose of this study was to characterize antibiotic resistance profiles of bacteria involved in the aetiology of PJIs. A total of 33 bacterial isolates cultured from 31 patients undergoing exchange of total hip prostheses were analyzed. The diagnostic approach toward isolation of prosthesis- associated microorganisms included sonication of retrieved implants and conventional cultures of periprosthetic tissues and synovial fluid. The in vitro resistance profiles of bacterial isolates were determined in relation to antibiotics recommended for the therapy of PJIs using the disc diffusion method, E-tests(®) and broth microdilution system. Coagulase-negative staphylococci (CNS) were predominant microorganisms followed by Staphylococcus aureus, Enterobacter cloacae, Streptococcus mitis, and Propionibacterium acnes. Twenty out of 30 and 12 out of 30 staphylococcal isolates were methicillin- and multi-drug resistant, respectively. Only two isolates were rifampicinresistant. All staphylococci were susceptible to glycopeptides and linezolid. This paper stresses the pathogenic role of staphylococci in patients suffering from implant loosening and reports high methicillin- and multidrug-resistance rates in these bacteria. Hence, antimicrobial susceptibility tests of individual bacterial isolates must always be performed to guide selection of the optimal therapeutic option.

  14. Bacterial fitness shapes the population dynamics of antibiotic-resistant and -susceptible bacteria in a model of combined antibiotic and anti-virulence treatment

    Science.gov (United States)

    Ternent, Lucy; Dyson, Rosemary J.; Krachler, Anne-Marie; Jabbari, Sara

    2015-01-01

    Bacterial resistance to antibiotic treatment is a huge concern: introduction of any new antibiotic is shortly followed by the emergence of resistant bacterial isolates in the clinic. This issue is compounded by a severe lack of new antibiotics reaching the market. The significant rise in clinical resistance to antibiotics is especially problematic in nosocomial infections, where already vulnerable patients may fail to respond to treatment, causing even greater health concern. A recent focus has been on the development of anti-virulence drugs as a second line of defence in the treatment of antibiotic-resistant infections. This treatment, which weakens bacteria by reducing their virulence rather than killing them, should allow infections to be cleared through the body׳s natural defence mechanisms. In this way there should be little to no selective pressure exerted on the organism and, as such, a predominantly resistant population should be less likely to emerge. However, before the likelihood of resistance to these novel drugs emerging can be predicted, we must first establish whether such drugs can actually be effective. Many believe that anti-virulence drugs would not be powerful enough to clear existing infections, restricting their potential application to prophylaxis. We have developed a mathematical model that provides a theoretical framework to reveal the circumstances under which anti-virulence drugs may or may not be successful. We demonstrate that by harnessing and combining the advantages of antibiotics with those provided by anti-virulence drugs, given infection-specific parameters, it is possible to identify treatment strategies that would efficiently clear bacterial infections, while preventing the emergence of antibiotic-resistant subpopulations. Our findings strongly support the continuation of research into anti-virulence drugs and demonstrate that their applicability may reach beyond infection prevention. PMID:25701634

  15. Bacterial fitness shapes the population dynamics of antibiotic-resistant and -susceptible bacteria in a model of combined antibiotic and anti-virulence treatment.

    Science.gov (United States)

    Ternent, Lucy; Dyson, Rosemary J; Krachler, Anne-Marie; Jabbari, Sara

    2015-05-07

    Bacterial resistance to antibiotic treatment is a huge concern: introduction of any new antibiotic is shortly followed by the emergence of resistant bacterial isolates in the clinic. This issue is compounded by a severe lack of new antibiotics reaching the market. The significant rise in clinical resistance to antibiotics is especially problematic in nosocomial infections, where already vulnerable patients may fail to respond to treatment, causing even greater health concern. A recent focus has been on the development of anti-virulence drugs as a second line of defence in the treatment of antibiotic-resistant infections. This treatment, which weakens bacteria by reducing their virulence rather than killing them, should allow infections to be cleared through the body׳s natural defence mechanisms. In this way there should be little to no selective pressure exerted on the organism and, as such, a predominantly resistant population should be less likely to emerge. However, before the likelihood of resistance to these novel drugs emerging can be predicted, we must first establish whether such drugs can actually be effective. Many believe that anti-virulence drugs would not be powerful enough to clear existing infections, restricting their potential application to prophylaxis. We have developed a mathematical model that provides a theoretical framework to reveal the circumstances under which anti-virulence drugs may or may not be successful. We demonstrate that by harnessing and combining the advantages of antibiotics with those provided by anti-virulence drugs, given infection-specific parameters, it is possible to identify treatment strategies that would efficiently clear bacterial infections, while preventing the emergence of antibiotic-resistant subpopulations. Our findings strongly support the continuation of research into anti-virulence drugs and demonstrate that their applicability may reach beyond infection prevention.

  16. 由细菌耐药机制探讨临床抗生素的合理应用%Bacterial Resistance and Reasonable Application of the Antibiotics

    Institute of Scientific and Technical Information of China (English)

    陈世玲

    2013-01-01

    目的:通过对细菌耐药机制的分析,探讨临床上抗生素的合理使用,以应对细菌的耐药性.方法:结合已有文献报道和多年临床经验,分析细菌的耐药机制,探讨临床抗生素的合理应用原则和方法.结果:细菌的耐药机制分为遗传学机制和生化机制,其耐药性的产生与抗生素灭活酶的产生、膜通透性改变、新靶位的产生和改变等有关.结论:合理使用抗生素,防止其滥用,能有效较少细菌耐药性的产生.%Objective: By analyzing the mechanisms of bacterial resistance, to explore the rational clinical use of antibiotics. Method: According to the literatures reportsd and the clinical experiences, the mechanisms of bacterial resistance has been discussed. Result: The bacterial resistance mechanisms were divided into the genetic mechanisms and biochemical mechanisms. The produce of drug resistance was related to the produce of inactivation enzymes, the changes of the membrane permeability, the generation of new targets and so on. Conclusion: The rational use of antibiotics can effectively reduce the produce of bacterial drug resistance.

  17. Resistance and Inactivation Kinetics of Bacterial Strains Isolated from the Non-Chlorinated and Chlorinated Effluents of a WWTP

    Science.gov (United States)

    Martínez-Hernández, Sylvia; Vázquez-Rodríguez, Gabriela A.; Beltrán-Hernández, Rosa I.; Prieto-García, Francisco; Miranda-López, José M.; Franco-Abuín, Carlos M.; Álvarez-Hernández, Alejandro; Iturbe, Ulises; Coronel-Olivares, Claudia

    2013-01-01

    The microbiological quality of water from a wastewater treatment plant that uses sodium hypochlorite as a disinfectant was assessed. Mesophilic aerobic bacteria were not removed efficiently. This fact allowed for the isolation of several bacterial strains from the effluents. Molecular identification indicated that the strains were related to Aeromonas hydrophila, Escherichia coli (three strains), Enterobacter cloacae, Kluyvera cryocrescens (three strains), Kluyvera intermedia, Citrobacter freundii (two strains), Bacillus sp. and Enterobacter sp. The first five strains, which were isolated from the non-chlorinated effluent, were used to test resistance to chlorine disinfection using three sets of variables: disinfectant concentration (8, 20 and 30 mg·L−1), contact time (0, 15 and 30 min) and water temperature (20, 25 and 30 °C). The results demonstrated that the strains have independent responses to experimental conditions and that the most efficient treatment was an 8 mg·L−1 dose of disinfectant at a temperature of 20 °C for 30 min. The other eight strains, which were isolated from the chlorinated effluent, were used to analyze inactivation kinetics using the disinfectant at a dose of 15 mg·L−1 with various retention times (0, 10, 20, 30, 60 and 90 min). The results indicated that during the inactivation process, there was no relationship between removal percentage and retention time and that the strains have no common response to the treatments. PMID:23924881

  18. Resistance and Inactivation Kinetics of Bacterial Strains Isolated from the Non-Chlorinated and Chlorinated Effluents of a WWTP

    Directory of Open Access Journals (Sweden)

    Claudia Coronel-Olivares

    2013-08-01

    Full Text Available The microbiological quality of water from a wastewater treatment plant that uses sodium hypochlorite as a disinfectant was assessed. Mesophilic aerobic bacteria were not removed efficiently. This fact allowed for the isolation of several bacterial strains from the effluents. Molecular identification indicated that the strains were related to Aeromonas hydrophila, Escherichia coli (three strains, Enterobacter cloacae, Kluyvera cryocrescens (three strains, Kluyvera intermedia, Citrobacter freundii (two strains, Bacillus sp. and Enterobacter sp. The first five strains, which were isolated from the non-chlorinated effluent, were used to test resistance to chlorine disinfection using three sets of variables: disinfectant concentration (8, 20 and 30 mg·L−1, contact time (0, 15 and 30 min and water temperature (20, 25 and 30 °C. The results demonstrated that the strains have independent responses to experimental conditions and that the most efficient treatment was an 8 mg·L−1 dose of disinfectant at a temperature of 20 °C for 30 min. The other eight strains, which were isolated from the chlorinated effluent, were used to analyze inactivation kinetics using the disinfectant at a dose of 15 mg·L−1 with various retention times (0, 10, 20, 30, 60 and 90 min. The results indicated that during the inactivation process, there was no relationship between removal percentage and retention time and that the strains have no common response to the treatments.

  19. Study the effect of bacterial 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase on resistance to salt stress in tomato plant

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    Maryam SADRNIA

    2011-11-01

    Full Text Available 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase produced by rhizobacteria could be remove theethylene precursor and stimulate plant growth. Aim of the work was investigation on effect of rhizosphere bacteria Pseudomonasmendocina containing plasmid carrying gene encoding ACC deaminase on resistance of tomato plant to salinity. Amplification ofacds gene in selected Pseudomonas was performed; the g e n e w a s c l o n e d i n Escherichia coli and was cloned subsequently in P.mendocina. Enzyme activity was determined in cloned Escherichia coli and cloned P. mendocina for confirmation of geneexpression. Effect of bacterial ACC deaminase on resistance of tomato plants to NaCl was studied in Pot and Greenhouse. In potexperiment, tomato plant treated by cloned P. mendocina was compared with plants treated by P. mendocina (without plasmid andcontrol group. Salinity were established by adding 172 and 207 mM of NaCl to irrigated water. Greenhouse experiments wereconducted in similar groups of bacteria in 207 mM of NaCl. Results obtained from pot experiment revealed that plants treated bycloned P. mendocina in 172 mM of NaCl was showed increasing content of growth than ones treated by P. mendocina and controlas 11%, 18.4% growth for the shoot, 16.6%, 3.7% for roots and 9.6%, 27.5% for wet weight after five weeks, respectively. In 207mM of NaCl, the results were as 14.9 %, 9.7% for shoot, 94.3%, 15.7% for roots and 96.4%, 50.6% for wet weight, respectively. Ingreenhouse experiment, results in same parameter in 207 mM of NaCl were revealed as 63.7%, 7 times for shoot, 2.8, 14 times forroots and 66.1%, 154 times for wet weight, respectively. We concluded that recombinant P. mendocina producing ACC deaminaseby reduction of ethylene content of tomato plant in high salt concentrations could result in improvement of plant resistance tosalinity.

  20. Arabidopsis nonhost resistance gene PSS1 confers immunity against an oomycete and a fungal pathogen but not a bacterial pathogen that cause diseases in soybean

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    Sumit Rishi

    2012-06-01

    Full Text Available Abstract Background Nonhost resistance (NHR provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Three Arabidopsis thaliana PEN (penetration deficient genes, PEN1, 2 and 3 have been shown to provide NHR against the barley pathogen Blumeria graminis f. sp. hordei at the prehaustorial level. Arabidopsis pen1-1 mutant lacking the PEN1 gene is penetrated by the hemibiotrophic oomycete pathogen Phytophthora sojae, the causal organism of the root and stem rot disease in soybean. We investigated if there is any novel nonhost resistance mechanism in Arabidopsis against the soybean pathogen, P. sojae. Results The P.sojaesusceptible (pss 1 mutant was identified by screening a mutant population created in the Arabidopsis pen1-1 mutant that lacks penetration resistance against the non adapted barley biotrophic fungal pathogen, Blumeria graminis f. sp. hordei. Segregation data suggested that PEN1 is not epistatic to PSS1. Responses of pss1 and pen1-1 to P. sojae invasion were distinct and suggest that PSS1 may act at both pre- and post-haustorial levels, while PEN1 acts at the pre-haustorial level against this soybean pathogen. Therefore, PSS1 encodes a new form of nonhost resistance. The pss1 mutant is also infected by the necrotrophic fungal pathogen, Fusarium virguliforme, which causes sudden death syndrome in soybean. Thus, a common NHR mechanism is operative in Arabidopsis against both hemibiotrophic oomycetes and necrotrophic fungal pathogens that are pathogenic to soybean. However, PSS1 does not play any role in immunity against the bacterial pathogen, Pseudomonas syringae pv. glycinea, that causes bacterial blight in soybean. We mapped PSS1 to a region very close to the southern telomere of chromosome 3 that carries no known disease resistance genes. Conclusions The study revealed that Arabidopsis PSS1 is a novel nonhost resistance gene that confers a new form of

  1. Etablierung des Nachweises direkter antibakterieller Wirkung humaner Defensine für die Untersuchung der Defensinproduktion im menschlichen Darm bei Morbus Crohn und Colitis ulcerosa

    OpenAIRE

    Andreou, Andreas

    2010-01-01

    Introduction: As a part of the innate immunity, defensins support the preservation of the intestinal mucosal barrier which is affected in patients with inflammatory bowel disease (IBD). It is interesting whether a potential direct antibacterial activity of defensins in the bowel of IBD patients is changed compared to healthy persons. Since the mechanisms of defensin action are not fully understood, defensins themselves are the only reliable controls in respective studies. Methods: A densit...

  2. Jasmonate induction of the monoterpene linalool confers resistance to rice bacterial blight and its biosynthesis is regulated by JAZ protein in rice.

    Science.gov (United States)

    Taniguchi, Shiduku; Hosokawa-Shinonaga, Yumi; Tamaoki, Daisuke; Yamada, Shoko; Akimitsu, Kazuya; Gomi, Kenji

    2014-02-01

    Jasmonic acid (JA) is involved in the regulation of host immunity in plants. Recently, we demonstrated that JA signalling has an important role in resistance to rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice. Here, we report that many volatile compounds accumulate in response to exogenous application of JA, including the monoterpene linalool. Expression of linalool synthase was up-regulated by JA. Vapour treatment with linalool induced resistance to Xoo, and transgenic rice plants overexpressing linalool synthase were more resistance to Xoo, presumably due to the up-regulation of defence-related genes in the absence of any treatment. JA-induced accumulation of linalool was regulated by OsJAZ8, a rice jasmonate ZIM-domain protein involving the JA signalling pathway at the transcriptional level, suggesting that linalool plays an important role in JA-induced resistance to Xoo in rice.

  3. Identification of pathotypes of Xanthomonas axonopodis pv. manihotis in Africa and detection of quantitative trait loci and markers for resistance to bacterial blight of Cassava

    OpenAIRE

    Wydra, Kerstin; Zinsou, Valerien; Jorge, Véronique; Verdier, Valérie

    2004-01-01

    Cassava suffers from bacterial blight attack in all growing regions. Control by resistance is unstable due to high genotype–environment interactions. Identifying genes for resistance to African strains of Xanthomonas axonopodis pv. manihotis can support breeding efforts. Five F1 cassava genotypes deriving from the male parent ‘CM2177-2’ and the female parent ‘TMS30572’ were used to produce 111 individuals by backcrossing to the female parent. In all, 16 genotypes among the mapping population ...

  4. Resistência de bactérias ácido-láticas a bacteriófagos provenientes de unidades de processamento de queijo Coalho Phage resistance of acid lactic bacteria isolated from Coalho cheese industries

    Directory of Open Access Journals (Sweden)

    Cristiane Pereira de Lima

    2012-06-01

    Full Text Available Este trabalho teve como objetivos isolar bacteriófagos de amostras de leite, soro e queijo de Coalho e avaliar a resistência de cepas de Lactobacillus paracasei, pertencentes à Coleção de Micro-organismos de Interesse para a Agroindústria Tropical da Embrapa Agroindústria Tropical, aos fagos isolados. Posteriormente, a resistência destas cepas a fagos específicos para L. paracasei, da Coleção do Instituto de Lactología Industrial - INLAIN (Santa Fe, Argentina, também foi avaliada. As amostras para isolamento dos fagos foram obtidas em quatro unidades de processamento de queijo de Coalho, sendo duas artesanais e duas industriais, localizadas no Estado do Ceará. Para o isolamento dos bacteriófagos, foi empregado o teste de lise celular (spot, enquanto que a resistência das culturas aos fagos foi avaliada pelos testes de capacidade de produção de ácido e avaliação da turbidez. As cepas avaliadas foram resistentes aos bacteriófagos provenientes das unidades de processamento de queijo de Coalho e aos bacteriófagos da Coleção do INLAIN. Os resultados obtidos indicaram que as culturas láticas testadas, resistentes aos bacteriófagos, podem ser utilizadas na composição de fermento lático destinado à elaboração de queijo de Coalho, a partir de leite pasteurizado.The objectives of this research were to isolate bacteriophages from milk samples, whey and Coalho cheese and to evaluate the resistance of strains of Lactobacillus paracasei from the Collection of Microorganisms of Interest for the Tropical Agroindustry, belonging to Embrapa Tropical Agroindustry, to isolate phages. The strains resistance to specific L. paracasei phages from the collection of the Instituto de Lactología Industrial - INLAIN (Santa Fe, Argentina was also evaluated. Samples for phage isolation were from four Coalho cheese processing units, two artisanal and two industrial, localized in the state of Ceará. Spot test was employed for bacteriophages

  5. Stata统计软件在细菌耐药性实验中的应用%Application of Stata on the Experiment of Bacterial Resistance

    Institute of Scientific and Technical Information of China (English)

    张少俊; 莫传伟; 彭拓华; 钟世顺; 杨彤

    2012-01-01

    Objective This article introduce a new method to carry on the experiment of bacterial resistance design with the statistical software-stata. Methods Using the command group and the command replace achieve both equal and unequal probability allocations of the experiment of bacterial resistance. Using the swor command could ensure all samplings without repetitions. Results It's convenient to design the experiment of bacterial resistance with the help of Stata. Conclusion Compared with manual and excel allocations, Stata is a statistical software that is easy to learn, simple to operate and has high repeatability.%目的 应用Stata统计软件细菌耐药性辅助实验设计.方法 应用Stata统计软件中的group、replace对细菌耐药性实验进行等概率与不等概率的分组,应用swor命令实现无重复抽样.结果 Stata统计软件能够方便的辅助细菌耐药性实验设计.结论 对比手工分组与excel分组,Stata统计软件好学易用,操作简单,可重复性高.

  6. Resistance mechanisms of bacterial and rational use of antibiotics%细菌耐药机制与抗菌药物的合理应用

    Institute of Scientific and Technical Information of China (English)

    何洪海

    2011-01-01

    随着抗菌药物的广泛应用,越来越多的细菌出现耐药性,而且耐药程度也越来越高.细菌的耐药成为感染性疾病中治疗的难题,常因此而导致疗程的延长、费用的增加以及死亡率的升高,造成了巨大的经济损失.本文综述了近年来国内外细菌耐药机制的研究进展,并结合本院实际工作提出合理使用抗菌药物的建议.%With the extensive use of anti-bacterial agents, the bacteria appear more and more resistance. Bacteria become resistant to the treatment of infectious diseases, often leading to extended treatment course, in-creased costs and increased mortality and causing enormous economic losses. In this paper, the mechanism of bacterial resistance in recent years were elaborated, as well as how to use anti-bacterial agents reasonably combining with the actual work.

  7. Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells

    Science.gov (United States)

    Sanyasi, Sridhar; Majhi, Rakesh Kumar; Kumar, Satish; Mishra, Mitali; Ghosh, Arnab; Suar, Mrutyunjay; Satyam, Parlapalli Venkata; Mohapatra, Harapriya; Goswami, Chandan; Goswami, Luna

    2016-04-01

    Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20–40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells.

  8. A Family of CSαβ Defensins and Defensin-Like Peptides from the Migratory Locust, Locusta migratoria, and Their Expression Dynamics during Mycosis and Nosemosis.

    Science.gov (United States)

    Lv, Mingyue; Mohamed, Amr Ahmed; Zhang, Liwei; Zhang, Pengfei; Zhang, Long

    2016-01-01

    Insect defensins are effector components of the innate defense system. During infection, these peptides may play a role in the control of pathogens by providing protective antimicrobial barriers between epithelial cells and the hemocoel. The cDNAs encoding four defensins of the migratory locust, Locusta migratoria, designated LmDEF 1, 3-5, were identified for the first time by transcriptome-targeted analysis. Three of the members of this CSαβ defensin family, LmDEF 1, 3, and 5, were detected in locust tissues. The pro regions of their sequences have little-shared identities with other insect defensins, though the predicted mature peptides align well with other insect defensins. Phylogenetic analysis indicates a completely novel position of both LmDEF 1 and 3, compared to defensins from hymenopterans. The expression patterns of the genes encoding LmDEFs in the fat body and salivary glands were studied in response to immune-challenge by the microsporidian pathogen Nosema locustae and the fungus Metarhizium anisopliae after feeding or topical application, respectively. Focusing on Nosema-induced immunity, qRT-PCR was employed to quantify the transcript levels of LmDEFs. A higher transcript abundance of LmDEF5 was distributed more or less uniformly throughout the fat body along time. A very low baseline transcription of both LmDEFs 1 and 3 in naïve insects was indicated, and that transcription increases with time or is latent in the fat body or salivary glands of infected nymphs. In the salivary glands, expression of LmDEF3 was 20-40-times higher than in the fat body post-microbial infection. A very low expression of LmDEF3 could be detected in the fat body, but eventually increased with time up to a maximum at day 15. Delayed induction of transcription of these peptides in the fat body and salivary glands 5-15 days post-activation and the differential expression patterns suggest that the fat body/salivary glands of this species are active in the immune response

  9. A Family